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bacteriology
The bacteriology part of medical microbiology is full of knowledge points! If you want to learn about bacteriology, you must not miss this mind map! Let you understand and learn more quickly and conveniently. It is recommended to collect and study!
Edited at 2024-03-28 17:21:17
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bacteriology
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This Valentine's Day brand marketing handbook provides businesses with five practical models, covering everything from creating offline experiences to driving online engagement. Whether you're a shopping mall, restaurant, or online brand, you'll find a suitable strategy: each model includes clear objectives and industry-specific guidelines, helping brands transform traffic into real sales and lasting emotional connections during this romantic season.
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- Milano Cortina 2026 Ice Hockey Schedule
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bacteriology
structure of bacteria
Bacterial size and shape
cocci
diplococci
Neisseria meningitidis
Streptococcus pneumoniae
Streptococcus
beta-hemolytic streptococci
staphylococcus
Staphylococcus aureus
Tetragenococcus
Gaffia tetrad
Sarcina
Sarcina luteus
bacilli
Streptobacterium
Corynebacterium
coccobacilli
Mycobacteria
Bifidobacteria
Spiral bacteria
Vibrio
only one bend
spirillum
There are more than two bends
Helicobacter
Continuously curved in a spiral shape
Campylobacter
U shape S shape
structure of bacteria
basic structure of cells
cell wall
Gram-positive bacteria (purple)
special components of cell wall
Peptidoglycan (15~50 layers)
glycan backbone
Tetrapeptide side chain: progulin
Pentapeptide cross-linking bridge: glycine
Three-dimensional structure
Phosphate wall
wall phosphate wall
membrane phosphate wall
Gram-negative bacteria (red)
special components of cell wall
adventitia
Lipopolysaccharide LPS (G endotoxin)
Lipid A
Is the main component of the toxicity and biological activity of endotoxins
Not species specific
core polysaccharide
Genus specific
specific polysaccharide
That is, the bacterial antigen of G (O antigen)
lipid bilayer
lipoprotein
Peptidoglycan (1~2 layers)
glycan backbone
Tetrapeptide side chain
Single layer planar network two-dimensional structure
Not sensitive to lysozyme/penicillin
Outer membrane porins can block the entry of lysozyme, antibiotics, and basic dyes
role of cell wall
Protect bacteria and maintain bacterial morphology
material exchange
related to pathogenicity
related to drug resistance
Related to electrostatic properties
Bacterial cell wall defective type (bacterial L-type)
definition
The peptidoglycan structure of the bacterial cell wall is directly damaged or its synthesis is inhibited by physical, chemical or biological factors, and it can survive in a hypertonic environment.
Mycoplasmas are naturally cell wall-less microorganisms, unlike the bacterial L-type
type
G bacteria: protoplast
G-bacteria: spheroplasts
nourish
Hypertonic low agar serum-containing medium
Growth and reproduction are slower than the original bacteria
Pathogenicity
Causes chronic infections: urinary tract infection, osteomyelitis, endocarditis
If clinical symptoms are obvious and bacterial isolation and culture of specimens are negative, L-type infection should be considered
artificial inducer
Lysostaphin/lysozyme
Cleavage of the β-1,4 glycosidic bond between N-acetylglucosamine and N-acetylmuramic acid in peptidoglycan
Destroy the glycan skeleton and cause cell lysis
penicillin
Competes with the transpeptidase danced during the synthesis of peptidoglycan by bacteria and inhibits the connection between the tetrapeptide side chain and the pentapeptide bridge.
It prevents bacteria from synthesizing complete peptidoglycan. It can survive under high osmotic pressure and die under normal osmotic pressure.
cell membrane
Function
material transport
respiration and secretion
Biosynthesis
Participate in bacterial division
intermediary
definition
It is a sac formed by the cell membrane invading, folding, and curling into the cytoplasm.
Function
Related to bacterial division, respiration, cell wall synthesis and spore formation
Mitochondria-like - Mitochondria-like
cytoplasm
Ribosome
Bacteria: 70S
Streptomycin-30S
Erythromycin-50S
Eukaryotic: 80S
60S 40S antibiotics don’t work
Plasmid
closed circular double-stranded DNA
Related to pathogenicity and drug resistance
cytoplasmic granules
special structure of cells
capsule
definition
The mucus material is firmly combined with the cell wall, with a thickness of z0.2um and an obvious boundary.
Features
Can identify and type bacteria
Important criteria for identifying bacteria
conditions needed to form
Affected by genetic control and environmental conditions
Special dyeing method is required
It has low affinity for general basic dyes and is commonly used for negative dyeing with ink.
Function
Antiphagocytosis
important virulence factors
adhesion
Resist the damaging effects of harmful substances
flagellum
Classification
Monotriatomycota, Dichotomycosis, Trachomycosis, Peritriatomycosis
Function
Is the motor organ of bacteria
Monochaeta is the fastest
Movement has a chemotaxis: moving towards nutrients and escaping from harmful substances
related to pathogenicity
Bacterial identification and classification
specific antigenicity
flagellar (H) antigen
pili
exist
Many G-bacteria and few G-bacteria
Must be observed with an electron microscope
Classification
Ordinary pili
It is a bacterial adhesion structure that can bind to specific receptors on the host cell surface.
closely related to the pathogenicity of bacteria
sex pili
Only found in a few G bacteria, in the shape of a hollow tube
Transmission: fertility, virulence, drug resistance
spores
Spores are not how bacteria reproduce
One bacterium only forms one spore, and one spore germinates and only produces one cell. The number of bacteria does not increase.
Strong resistance: Strong resistance to physical and chemical factors such as heat, drying, radiation, chemical disinfectants, etc.
Medical significance: Killing bacterial spores is used as an indicator to judge the sterilization effect.
The most reliable method: pressure steam sterilization
Bacterial inheritance and mutation
genetics
Characteristics of parents can be passed on to offspring through genetic material
Mutations
Gene mutation
The molecular structure of DNA, the genetic material of biological cells, suddenly undergoes stable and heritable changes.
Gene transfer and recombination
Convert
The recipient bacterium directly ingests the free DNA fragments of the donor bacterium and acquires new genetic traits (transformation can only be successful when the recipient bacterium is in a competent state)
join
The way bacteria communicate with each other through sexual pili and transfer genetic material (plasmid DNA) from donor bacteria to recipient bacteria
divert
Mediated by phage, the DNA fragment of the donor bacterium is transferred into the recipient bacterium, so that the recipient bacterium acquires some of the genetic traits of the donor bacterium.
Ordinary transduction
complete transduction
The exogenous DNA fragment integrates into the chromosome of the recipient bacteria and is passed along with the chromosome.
abortion transduction
Exogenous DNA fragments are free in the cytoplasm and cannot integrate with the recipient chromosome or replicate themselves.
localized transduction
Transduction is limited to specific genes on the chromosome of the donor bacterium, mediated by temperate phages
lysogenic switch
When a bacteriophage infects a bacterium, the host bacterium's chromosome acquires the phage's DNA fragment, causing it to become lysogenic, and the bacterium acquires new traits.
genetic material
chromosome
Carry most of the genetic information and determine the genotype of the bacteria
No introns
Bacterial chromosomes are haploid, circular closed double-stranded DNA
Plasmid
It is the extrachromosomal genetic material of bacteria and is a circular closed double-stranded DNA.
feature
autonomous replication
Can be lost or eliminated by oneself
metastatic
Phage genes
Phage
A virus that infects microorganisms such as bacteria, fungi, and tetrabodies
The structure of a bacteriophage
The nucleic acid is present in the head of the phage, and the protein constitutes the head capsid and tail structure of the phage.
Proliferation of phages
Replication cycle/lytic cycle
The process in which phage adsorbs host bacteria to lyse and release progeny phages
Adsorption, penetration, shelling, biosynthesis, maturation and release
Classification of phages
virulent bacteriophage
The phage infects the host bacterium, replicates and proliferates within the cell, produces a large number of progeny phages, and eventually lyses the host bacterium.
temperate bacteriophage
After the phage infects the host bacterium, it does not produce progeny phages or cause bacterial lysis. Instead, it integrates the genome into the host bacterium's chromosome, replicates with the replication of the host bacterium's genome, and is passed down as the bacterium divides.
Lysogenic
Temperate phages have the potential to produce mature progeny phages and lyse host bacteria.
transposable element
A unique DNA sequence that changes its position in the genome of a bacterium or other organism
Classification
insertion sequence
transposon
integron
Enterobacteriaceae
Escherichia
Escherichia coli
E. coli
Biological traits
Morphology
Gram-negative (G-) bacilli
periflagella
pili
Cultivation characteristics
Facultative anaerobic, low nutritional requirements
fermentable lactose
IMViC：＋＋－－
Antigen structure
O antigen
More than 170 bacterial antigens
H antigen
56 flagellar antigens
Pathogenicity
Pathogenic substances
Adhesin
pili
colonization factors
adherent mucosal epithelial cells
Exotoxins
Shiga toxin (Stx)
causing bloody diarrhea
Heat-labile enterotoxin (LT)
cause diarrhea
Heat-stable enterotoxin (ST)
cause diarrhea
Hemolysin A
UPEC urinary tract infection.
endotoxin
fever
K antigen
Has anti-phagocytic effect
Disease caused
extraintestinal infection
purulent infection
surgical wound infection
septicemia
neonatal meningitis
urinary tract infection
urinary tract infection
Cystitis
Pyelonephritis
More common in women
Intestinal infection
Gastrointestinal symptoms mainly diarrhea
microbiological examination
Detect pathogenic bacteria
Specimens: feces; urine, blood, pus, etc. for extraintestinal infection
Isolation, culture and identification
Detect toxins, virulence genes, and identify serotypes
ELISA detects toxins LT, ST, Stx
PCR or probe detection of virulence genes and plasmids
Standard identification of bacterial H and O serotypes
Indicators for sanitary bacteriological examination
The total number of bacteria per milliliter of drinking water and beverages must not exceed 100
The number of coliform bacteria per liter of drinking water must not exceed 3
Bottled drinks, etc., must not have more than 5 coliforms in 100ml
Epidemiology and general prevention and control principles
Source of infection
patients and carriers
way for spreading
feces-oral
vaccine
Pili, adhesion-related substances
Shigella
Shigella dysenteriae
Biological traits
Morphology
G-bacillus
Most have pili
No flagella, no capsule
Culture characteristics and biochemical reactions
Facultative anaerobic, low nutritional requirements
Colorless and transparent colonies on SS medium
Glucose +, Lactose -
IMViC:－＋－－
Antigen structure
O,K antigen
O antigen is the basis for classification and is divided into 4 groups (dysentery, dysentery, Bao, Song Nei)
Easy to mutate
resistance
weak
Pathogenicity
Pathogenic substances
Invasiveness
pili
Invasion protein
endotoxin
Exotoxins
Disease caused
bacillary dysentery
acute
acute bacillary dysentery
acute toxic dysentery
Chronic
Epidemiological characteristics
Source of infection
patient
carrier
way for spreading
Fecal-oral route of transmission
population susceptibility
The population is generally susceptible
microbiological examination
Detect pathogenic bacteria
specimen
Fresh, pus, blood, mucus parts
Cultivation and identification
Quick diagnosis
immune agglutination
bacteria, antigens, antibodies
PCR, molecular probe
large plasmid
Prevention and control principles
Managing sources of infection
Early detection, early isolation, early treatment, and thorough treatment
Catering and water supply personnel should be tested regularly
Cut off transmission routes
"Three pipes and one elimination" (that is, taking good care of water sources, food and feces, and eliminating flies)
Pay attention to personal hygiene and wash hands
Protect vulnerable groups
The efficacy of dysentery vaccines is generally not certain
Salmonella
Biological traits
Morphology
Gram-negative (G-) bacilli
periflagella
pili
No capsule
Cultivation characteristics
Facultative anaerobic, low nutritional requirements
Lactose does not ferment and can be separated and identified on SS plates.
Antigen structure
O antigen: bacterial antigen, ≥58 types of antigen structures
H antigen: Flagellar antigen
resistance
hot
Sensitive, can be killed by boiling
Can be killed in 15-30 minutes at 65⁰C
environment
Can survive in water for 2-3 weeks
Can survive in feces for 1-2 months
Also spends winter in ice and frozen soil
Chemicals
Sensitive to common disinfectants
But highly resistant to bile salts
Classification
Salmonella typhi
Other Salmonella
Paratyphi A
Salmonella shawii
Salmonella hisi
Primary host: human
Salmonella Typhimurium
Salmonella choleraesuis
Primary host: animals
Salmonella Enteritidis
Host: humans, animals
Types and Characteristics of Human Salmonella Infections
Gastroenteritis (food poisoning)
Incidence
The most common salmonella infection, accounting for about 70%
incubation period
Short, 6-24 hours
Clinical symptoms
Fever, nausea and vomiting, abdominal pain and diarrhea
prognosis
Severe cases
Dehydration, shock, kidney failure (infants, elderly, frail)
general
Self-healing in 2-3 days
septicemia
common crowd
More common in children and immunocompromised adults
Clinical symptoms
High fever, chills, anorexia
prognosis
Meningitis, osteomyelitis, cholecystitis, endocarditis caused by purulent infection
enteric fever
Clinical symptoms
persistent high fever
Roseola
Hepatosplenomegaly
Systemic poisoning
Typhoid appearance, hardness of hearing, relatively slow pulse
complication
Intestinal mucosal damage
Intestinal bleeding, intestinal perforation
Asymptomatic carriers
feature
Salmonella can still be detected 1 year after symptoms disappear
Incidence
About 1%-5%; related to age and gender
harm
Disease spread control becomes more difficult
microbiological examination
Pathological examination
Detect pathogenic bacteria
specimen
Blood (1 to 2 weeks), feces (2nd week onwards), urine (3rd week onwards) starting), bone marrow (whole process)
Food poisoning by taking vomitus or suspicious food
Taking blood for sepsis
Cultivation and identification
SS culture plate
serology test
Detect antibodies
Widal test
Using known Salmonella typhi O and H antigens and Salmonella Paratyphi A H A semi-quantitative agglutination test is performed between the antigen and the patient's serum to determine the tested serum Whether there are corresponding antibodies and their titers
Result analysis
O antibody (IgM type antibody)
H antibody (IgG type antibody)
Epidemiology and general prevention and control principles
Source of infection
patients and carriers
way for spreading
feces-oral
population susceptibility
People are generally susceptible to typhoid fever
Prevention and control principles
Strengthen food hygiene management and pay attention to those who excrete bacteria without symptoms
Inoculation with typhoid Vi polysaccharide vaccine, the protection rate is about 70%
Symptomatic treatment; fluoroquinolone treatment
Similarity
G-bacilli, flagellum + (except Shigella dysenteriae)
The nutritional requirements for culture are not high, and SS plates can distinguish pathogenic bacteria.
Active biochemical reactions (sugar fermentation)
Identification of pathogenic bacteria in lactose fermentation: non-pathogenic, - pathogenic
Antigen structure is complex
O antigen, H antigen, surface (K, Vi) antigen
susceptible to drug resistance
Bacterial infection and immunity
Bacterial infection refers to a series of pathological changes caused by bacteria that invade the host body, grow and reproduce and interact with the body.
Infection is the process by which pathogenic bacteria pass from one host to another and cause infection.
normal flora
It refers to the bacterial group that normally resides in the host body and is harmless and beneficial to the host. It is an important component of the host microbiota.
Physiological effects
Biological antagonism, nutritional effect, immune effect, anti-aging effect
opportunistic pathogens
When the ecological balance between normal flora and the host is imbalanced, some normal flora will become opportunistic pathogens and cause disease in the host. Therefore, opportunistic pathogens are also called opportunistic pathogens.
Changes in the residence site of normal flora, decreased host immune function, and dysbiosis
Pathogenic effects of bacteria
Bacterial invasiveness: refers to the ability of pathogenic bacteria to break through physiological barriers such as the host's skin and mucous membranes, enter the body, colonize, reproduce and spread in the body.
Related substances or structures: adhesins, capsules, invasive enzymes, invasive proteins, bacterial biofilms
toxin
Exotoxins
Main features
The chemical nature of most exotoxins is protein: most exotoxins have an A-B molecular structure
Strong toxicity and high selectivity to tissues and organs
Most exotoxins are heat-labile
Strong antigenicity
Classification
Classification and effects of exotoxins. According to the affinity of exotoxins to host cells and their targets, exotoxins can be divided into neurotoxins, cytotoxins and enterotoxins.
endotoxin
Main features
Endotoxins are lipopolysaccharides (lipopolysaccharides) in the cell wall of Gram-negative bacteria and are only released after the bacteria die and lyse.
Found in the cell wall of Gram-negative bacteria
Chemical properties: lipopolysaccharide
Stable to physical and chemical factors
The toxic effects are relatively weak and non-selective to tissues
Cannot use formaldehyde solution to detoxify and become toxoid
The main pathophysiological reactions caused by
Causes febrile reaction, changes in white blood cell count, endotoxemia and endotoxic shock
Pathogenic mechanism
Genes involved in inflammation and early defense responses, genes involved in specific immunity, and genes involved in apoptosis
in vivo induced antigens
Some bacterial genes are not expressed under artificial culture conditions, but are only induced to express after entering the host body. Such genes whose expression is induced only when bacteria invade the host are called in vivo induced genes.
superantigen
It is a type of special antigen with super ability to stimulate lymphocyte proliferation and stimulate the production of excessive T cells and cytokines. Its ability to stimulate lymphocyte proliferation is thousands of times that of plant lectins.
immunopathological damage
In the case of microbial infection, some antigenic substances that are not directly toxic may activate the body's immune response and cause immunopathological damage to tissue cells based on a hypersensitivity reaction mechanism, eventually leading to disease.
host immunity against infection
innate immunity
barrier structure
phagocyte
humoral factors
adaptive immunity
Humoral immunity
cellular immunity
mucosal immunity
anti-intracellular bacterial immunity
Effect of phagocytes on intracellular bacteria
The effect of cellular immunity on intracellular bacteria
Effect of specific antibodies on intracellular bacteria
Occurrence and development of infection
Source of infection
exogenous infection
Patients, carriers, sick animals and carrier animals
endogenous infection
way for spreading
Many pathogenic bacteria of the respiratory tract can enter the respiratory tract from the sputum, saliva and other secretions of patients and carriers, and cause infection through aerosols, air droplets and dust contaminated with pathogenic bacteria.
Certain pathogenic bacteria in the digestive tract enter and are excreted from the digestive tract, and then contaminate food, drinking water, etc., and then are introduced to new hosts through contaminated food, drinking water, etc., forming a "fecal-oral transmission route"
arthropod vector
sexually transmitted
spread through multiple channels
Type of infection
latent infection
Overt infection
Clinically, overt infections can be divided into acute infections and chronic infections according to the severity of the disease. Overt infections can be divided into local infections and systemic infections according to the location of infection. (Systemic infections are divided into toxemia, endotoxemia, bacteremia, sepsis, and sepsis)
occurrence of infection
Bacterial factors (virulence, quantity, site of invasion) Social and environmental factors
Hospital Infection
Classification
endogenous nosocomial infection
exogenous nosocomial infection
cross infection
environmental infection
hospital-acquired infection
Microbial characteristics of hospital infections: mainly opportunistic pathogens, often drug-resistant, and often changing species
Risk factors for hospital infections
Hospitals are the concentration of susceptible subjects to nosocomial infections: age factors, underlying diseases
Diagnosis and treatment technology: organ transplantation, hemodialysis and peritoneal dialysis
Invasive treatment: invasive examination, invasive treatment
Factors that damage the immune system: radiation therapy, chemotherapy, hormone use, other risk factors
Prevention and control of hospital infections
Disinfection and sterilization, isolation and prevention, and rational use of antibacterial drugs
respiratory bacteria
Mycobacterium tuberculosis
biological properties
Morphological staining
slender curved branches
Acid-fast staining (+)
No flagella
No spores
No internal or external toxins
capsule
Cultivation characteristics
obligate aerobic
High nutritional requirements (Roche medium)
Slow growth, takes 3-4w
PH value 6.5-6.8 (acidic)
resistance
Three antibodies
Anti-drying
Resistant to disinfectants
Resistant to acids and alkalis (miscellaneous bacteria in specimens can be treated with acids and alkalis)
Three fears
Damp heat: 60℃×30′ can kill
Ultraviolet rays: The patient's clothing, etc. can be exposed to sunlight for 2 to 3 hours.
Alcohol: 75% alcohol 2′ kills
Pathogenicity
Pathogenic substances
Endotoxin-free, no exotoxins and invasive enzymes produced
Lipids
Phospholipids
Tuberculous nodule formation and caseous necrosis
Mycolic acid (cord-like factor)
causing granulomas
waxy D
trigger delayed hypersensitivity reaction
cerebroside sulfate
Inhibit phagosome-lysosome fusion
protein
Tuberculin, induces hypersensitivity reactions
capsule
Anti-phagocytosis, adhesion, and prevention of drugs from entering the bacteria
Disease caused
TB pathogenic role
Induces delayed-type hypersensitivity reactions and causes inflammation
lung infection
Primary versus post-primary infection
extrapulmonary infection
Systemic dissemination caused by menstrual blood
Cerebral tuberculosis, renal tuberculosis, intestinal tuberculosis, tuberculous peritonitis, etc.
Immunity
Intracellular parasitic bacteria, mainly cellular immunity
Infection immunity (bacterial immunity/infectious immunity)
Immunity exists only when TB or its components are present. When TB or its components disappear, immunity also disappears.
PPD test
method
PPD 5 units (0.1ml) intradermally on forearm, 48-72 hours later
Results and judgment
Local redness, swelling, induration, ulceration, and blisters are considered strong positive
Diameter <0.5cm negative
Diameter>0.5cm positive
Diameter>1.5cm Strong positive
Detection method
Direct smear: Collect specimens (sputum, pulmonary effusion) and then perform microscopic examination and isolation and culture.
treat
Treatment principles: early stage, combined medication, complete cure
prevention
Early detection, early isolation, early treatment • Vaccination with BCG vaccine
Mycobacterium leprae
biological properties
Morphological staining
The only bacteria that cannot be cultured artificially outside the body
The morphology and staining are similar to Mycobacterium tuberculosis, often arranged in bundles
Acid-fast staining +
No flagella, capsule, spores, etc.
Typical intracellular bacteria, visible leprosy cells
Pathogenicity
Pathogenic substances
Disease caused
It mainly invades the skin, mucous membranes and peripheral nerves. In the late stage, it can invade deep tissues and organs and form granulomatous lesions.
Tumor type/open leprosy
The patient has low immunity and is highly contagious. Leprosy nodules can be seen, mainly invading the skin, mucous membranes, nerves, and eyes.
Tuberculoid/atretic leprosy
The patient has strong immunity and Mycobacterium leprae is not easily detected in the body. It is less contagious and the lesions mainly invade the skin and peripheral nerves.
Immunity
Detection method
Take samples from nasal mucosa or lesions and stain them with acid-fast staining
treat
sulfones, welfare equality
prevention
Early detection, early isolation
Corynebacterium diphtheriae
biological properties
Morphological staining
G, without capsule or flagellum, does not produce spores, and has slender cells with one or both ends in the shape of a rod.
Neisser staining: bacteria appear bright yellow and metachromatic particles appear deep purple.
nourish
Lu's medium
Typical morphology, obvious metachromatic granules
Potassium tellurite blood plate
Diphtheria bacilli can reduce potassium tellurite to elemental tellurium, and the colonies appear black.
Tellurite can inhibit the growth of other bacteria, so it can be used as a medium for identification and selection of this bacteria.
resistance
Resistant to dryness and sunlight: Dry clothes and toys can survive for several weeks, so toys can be one of the routes of infection.
Sensitive to moisture and heat
Sensitive to penicillin and erythromycin
Not sensitive to sulfonamides
Pathogenicity
Pathogenic substances
Exotoxins: composed of two subunits A and B
– A: Inhibits cellular protein synthesis
– B: non-toxic, mediates binding to receptors on the surface of cardiomyocytes and nerve cells
Disease caused
Immunity
Immunity is strong after illness, mainly IgG
treat
Diphtheria antitoxin: skin test, if positive, desensitizing injection
Antibiotics (penicillin, erythromycin)
prevention
Artificial Active: Toxoid (Vaccination)
Bordetella pertussis
biological properties
Morphological staining
G-, short rod-shaped, without flagella, without spores
Toxic strains: have capsules and pili
nourish
Obligately aerobic, with high nutritional requirements, commonly used abalone-gold culture medium
Pathogenicity
Pathogenic process
Early patients and carriers → droplets → growth and reproduction in the upper respiratory tract for 9-10 days → toxin production → irritation of mucous membranes → exudative inflammation (catarrhal phase 7 to 10 days) → spasmodic cough (cramping phase 2 to 6 weeks) → Recovery period (weeks to months)
Paroxysmal spasmodic cough, often accompanied by inspiratory "rooster sounds"
Immunity
Strong immunity after illness
treat
Erythromycin, ampicillin
prevention
Injection of triple diphtheria-tetanus and pertussis vaccine
Legionella pneumophila
biological properties
Morphological staining
Legionella pneumophila lives in water, and it lives best in warm water.
Transmitted by respiratory infection, gusty/gentle wind
Intracellular parasitic bacteria, mainly cellular immunity
G-, not easy to stain
Polymorphous, flagellated
nourish
obligate aerobic
Pathogenicity
Disease caused
influenza-like
No pneumonia, self-limiting
pneumonia type
The onset is sudden, with chills, high fever, headache, and severe myalgia. Dry cough begins, followed by purulent sputum or hemoptysis, often accompanied by central nervous system and gastrointestinal symptoms.
Extrapulmonary infection type
Detection method
Sampling: respiratory secretions, lung biopsy tissue, urine, etc.
Immunofluorescence labeling: direct/indirect
treat
Erythromycin is preferred
Prevention and control
Strong resistance, widespread in water, pay attention to drinking water hygiene and prevent air conditioning pollution
Neisseria meningitidis
biological properties
form
G-, kidney-shaped or bean-shaped, arranged in pairs, concave surfaces facing each other, without flagella, with pili, and newly isolated bacteria mostly have capsules
Cultivation characteristics
High nutritional requirements: chocolate plate (cooked blood culture medium)
Specific need for O2: 5 to 10% CO2 is required during initial separation.
resistance
Sensitive to cold, heat, dryness and ultraviolet rays; destroyed at 55°C × 5′ and dead within 3 hours at room temperature
Pathogenicity
Pathogenic substances
Capsules and pili
endotoxin
Disease caused
Meningococcal meningitis (meningoencephalitis)
Immunity
Humoral immunity
Mainly IgG, but also IgM and IgA
Strong immunity after illness
The capsular polysaccharide in the group has Ag cross, and there is cross immunity
sIgA has a certain effect locally
Detection method
Specimens: cerebrospinal fluid (csf), blood, ecchymosis; direct microscopy: neutrophilic intragranular G-diplococci in csf can confirm the diagnosis
Prevention and control
vaccine
treat
penicillin
Streptococcus pneumoniae
biological properties
Morphological staining
G, spearhead-shaped, arranged in pairs, with broad ends facing each other and tips outward, with capsule
Cultivation characteristics
High nutritional requirements, blood plate
The colonies are similar to those of alpha-chain (small, gray-white, translucent, grass-green narrow α-hemolytic ring)
There are autolytic enzymes and "umbilicus"-shaped colonies
Pathogenicity
Pathogenic substances
Capsule: anti-MΦ and antimicrobial substances in body fluids
Pneumolysin O
purpura forming factor
Disease caused
Lobar pneumonia
It is more common in young adults. When the body's resistance decreases, it can cause disease in the lungs in the pharynx and multiply in the lungs. The onset is acute, chills, high fever, chest pain, and coughing up rust-colored sputum.
Otitis media, sinusitis, meningitis (high mortality in the elderly and children)
Immunity
Strong immunity
Detection method
Specimens (sputum, pus, csf) smear
Prevention and control methods
penicillin
Haemophilus influenzae
biological properties
G-, small B, highly polymorphous (ball, rod, rod), capsuled
High nutritional requirements, chocolate tablets, X, V growth factors
Pathogenicity
Primary infection: acute suppurative inflammation, laryngitis, meningitis
Secondary infections: caused by bacteria living in the upper respiratory tract, chronic bronchitis, pneumonia, otitis media, sinusitis, conjunctivitis
Immunity
Mainly HI, not strong, short maintenance time
Klebsiella pneumoniae
biological properties
G-, coccobacterium, with capsule, pili, no spores, low nutritional requirements, mucus-like colonies, and hemolysis on the blood plate
Pathogenicity
pneumoniae subspecies (Bacillus pneumoniae)
Pneumonia, lung abscess, bronchitis, meningitis, urinary tract infection and trauma infection, sepsis, etc.
This subspecies accounts for 95% of Klebsiella pneumoniae infections
Rhinitis subspecies (Rhinobacter odorifera)
chronic atrophic rhinitis
Rhinosclerotia subspecies (Mycobacterium rhinosclerosis)
Chronic granulomatous lesions of the nasopharynx
Prevention and control methods
Antibiotics, most of the infections are secondary infections, easy to be resistant, drug sensitivity is important
cocci
cocci
Gram-positive bacteria
Staphylococcus, Streptococcus, Streptococcus pneumoniae, Enterococcus
Gram-negative bacteria
Neisseria meningitidis, Neisseria gonorrhoeae
Staphylococcus
Staphylococcus aureus
Biological traits
Morphology and staining
Spherical, grape bunch-like arrangement, Gram-positive, no special structure
nourish
Transparent hemolytic ring: Staphylococcus aureus
Antigen - Staphylococcal protein A (SPA)
Specific binding to the Fc segment of IgG1, IgG2 and IgG4 molecules
SPA protein is present on the surface of more than 90% of Staphylococcus aureus cell walls
medical significance
Anti-phagocytosis: SPA competes with phagocytes for the Fc segment
synergistic agglutination test
Classification
According to pigments and biochemical reactions
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus saprophyticus
resistance
powerful
Sensitive to certain basic dyes such as gentian violet
Highly sensitive to penicillin, chlortetracycline, and gentamicin
Moderately sensitive to streptomycin
Poor sensitivity to sulfa and chloramphenicol
susceptible to drug resistance
Pathogenicity
Pathogenic substances
Bacterial surface structure and components: adhesins, capsules, SPA
invasive enzyme
coagulase
Concept: Enzymes that coagulate human or rabbit plasma containing anticoagulants
Significance: an important indicator for identifying pathogenicity
Pathogenesis
Resist phagocytosis by phagocytes
Protect germs from bactericidal substances in serum
localize infection and form thrombosis
Other enzymes
toxin
Staphylococcal lysin
alphalysin
Exotoxin, good antigenicity
Hemolytic effect on red blood cells of various mammals
Enterotoxins
About 50% of clinical isolates of Staphylococcus aureus can produce
Causes acute gastroenteritis (food poisoning)
Heat stable and resistant to hydrolysis by proteases in gastrointestinal fluids
Mechanism of action: Acts with intestinal nerve cell receptors to stimulate the vomiting center, leading to food poisoning with vomiting as the main symptom.
exfoliative toxin
Golden scalded skin syndrome (SSSS)
toxic shock syndrome toxin-1
It is an exotoxin that causes fever in the body and can increase the body's sensitivity to endotoxins.
Causes multi-organ system dysfunction or toxic shock syndrome (TSS)
Disease caused
purulent disease
purulent skin infection
Folliculitis, boils, carbuncles, wound suppuration and abscesses
Purulent infections of various organs
Tracheitis, endocarditis, pneumonia, otitis media, osteomyelitis
Clinically, more than 50% of acute infective endocarditis is caused by Staphylococcus aureus
systemic infection
Sepsis, sepsis
toxin disease
Immunity
Humans have some natural immunity to Staphylococcus aureus
microbiological examination
Staphylococcal enterotoxin test: ELISA method
Staphylococcus epidermidis
Main components of normal skin flora
Common bacteria in nosocomial infections: implant-related infections - urinary catheters, artificial valves, artificial joints, arterial catheters, pacemakers, etc.
identification
Not hemolytic
Plasma coagulase negative
Staphylococcus saprophyticus
urinary tract infection
sensitive to antibiotics
Streptococcus
Classification
According to the phenomenon of hemolysis
Group A hemolytic Streptococcus (alpha, incomplete hemolysis)
Beta-hemolytic Streptococcus (beta, complete hemolytic)
Streptococcus C: does not produce hemolysin, and there is no hemolytic ring around the colony
According to polysaccharide antigen
About 90% of streptococci that are pathogenic to humans belong to group A
Group A Streptococcus (pyogenic)
Biological traits
Morphology and staining
Spherical or oval, arranged in a chain
No spores, no flagella, pili-like structures
Cultivation characteristics
Gray-white round colonies can be formed on blood agar plates → β-hemolytic rings appear.
biochemical reaction
Decompose glucose-→produce acid but not gas
Does not decompose glucose and is not dissolved by bile - Differentiate between Streptococcus pneumoniae and other type A hemolytic streptococci
Streptococcus is different from Staphylococcus → catalase negative
Antigen structure
M antigen is associated with pathogenicity
resistance
Sensitive to common disinfectants
Pathogenicity
invasive force structure
Lipoteichoic acid (LTA)
LTA is an adhesion factor between Streptococcus pyogenes and host cells
cell wall receptor (F protein)
Facilitates bacterial adhesion to host cells
M protein
LTA surrounds the M protein and together with the M protein forms a pilus-like structure outside the cell wall, which has an anti-phagocytic effect.
invasive enzyme
Streptococci (SD)
Also known as Streptococcus DNase, it can break down the highly viscous DNA in pus, thin the pus, and promote the spread of germs.
Streptokinase (SK)
It can turn plasminogen in the blood into fibrinoprotein, dissolve blood clots or prevent plasma coagulation, which is conducive to the spread of bacteria in tissues.
Hyaluronidase
Also known as diffusion factor, it can decompose hyaluronic acid in tissues, making it easier for bacteria and their toxins to spread in tissues
toxin
Streptolysin: dissolves red blood cells and destroys white blood cells and platelets
SLO: Sensitive to O2, strong antigenicity, as an indicator of recent streptococcal infection - or an auxiliary diagnosis of rheumatic fever and its activity
SLS: stable to O2, non-immunogenic, and produces β-hemolytic ring
Pyrogenic exotoxins (scarlet fever toxin/erythema toxin): the main toxic substances causing scarlet fever in humans
microbiological examination
Check for pathogens
serology test
Resistance to "0 test"
Normal titer<1: 400
Significance: assists in the diagnosis of acute rheumatic fever, active rheumatic phase, and acute glomerulonephritis
Streptococcus pneumoniae
Biological traits
Morphology and staining
Grass-green hemolytic ring - similar to alpha-hemolytic streptococci
Pathogenicity
Capsule: Antigenic → divided into more than 90 serotypes
Mainly causes lobar pneumonia in humans, followed by bronchitis
Prevention and control principles
Multivalent pneumococcal capsular polysaccharide vaccine
Other streptococci
Group B Streptococcus
Main infections in neonates→sepsis, meningitis, pneumonia
Group D Streptococcus
Most infected people are elderly or young and middle-aged women
alpha-hemolytic streptococci
The most common opportunistic pathogen causing endocarditis
Streptococcus mutans
are anaerobic bacteria and are closely related to dental caries
Enterococcus
Neisseria
Neisseria meningitidis
Biological traits
Kidney-shaped or bean-shaped, G diplococcus, high nutritional requirements→chocolate color medium
Pathogenicity
Capsule, lipooligosaccharide (LOS is the main pathogenic substance of Neisseria meningitidis)
Disease caused
meningococcal meningitis
Immunity
Humoral immunity
Prevention and control principles
Meningococcal capsular polysaccharide vaccine
Neisseria gonorrhoeae
Biological traits
chocolate medium
Pathogenic substances
outer membrane protein
PI: destroy neutrophils
PII: involved in adhesion
PIII: Inhibits bactericidal antibody activity
IgA1 enzyme: destroys SIgA1 antibodies on mucosal surfaces
Fimbriae, lipooligosaccharides, etc.
Disease caused
Gonorrhea - Sexually transmitted (mainly)
Vertical transmission-→Neonatal gonococcal conjunctivitis
microbiological examination
Specimens: Keep warm and moisturized
direct smear microscopy
Isolation, culture and identification
Molecular biology testing
Prevention and control principles
1% silver nitrate eye drops-->prevent neonatal gonococcal conjunctivitis
There is currently no effective vaccine-specific prevention
anaerobic bacteria
definition
It refers to a group of bacteria that can only grow and reproduce under anaerobic or low-oxygen conditions and use anaerobic respiration and fermentation to obtain energy.
Anaerobic Clostridium
Features
Gram-positive, spore-forming, widely found in soil, water, sewers, human and animal intestines and feces
Clostridium tetani
biological properties
Strictly anaerobic, G, the bacteria are slender, have spores, and are drumstick-shaped. The spores are highly resistant and can survive in the soil for decades. They can be destroyed at 100°C in 1 hour and can enter through wounds.
The formation of anaerobic microenvironment in wounds: narrow and deep wounds (such as stab wounds), large-area wounds and burns contaminated by soil or foreign matter, many necrotic tissues, local tissue ischemia, and a mixture of aerobic bacteria or facultative anaerobic bacteria Infect
Pathogenicity
Tetanus spasm toxin is produced. Clostridium tetani only reproduces locally, and its causative substance is exotoxin. The spasm toxin produced in local wounds invades the spinal cord through lymph, blood flow or peripheral nerve endings in a retrograde motion along the axon. For anterior horn and brainstem neurons, the incubation period is usually 1-3 weeks, which is related to the distance between the primary infection site and the central nervous system.
Mechanism
Neurotoxin, extremely toxic, protein, heat-labile, A-B toxin. The toxin binds to motor neuron receptors, preventing the release of inhibitory neurotransmitters, causing spastic paralysis and simultaneous strong contraction of flexor and extensor muscles. (the unique face of tetanus)
Immunity
Once exotoxins, humoral immunity, and tetanus spasm toxin bind to central nervous tissue, they cannot be neutralized by antitoxins.
microbiological examination
Typical symptoms and medical history can be used to make the diagnosis. Generally, smear microscopy and isolation culture are not performed. Tetanus rods grow on pork broth culture medium (turbidity and blackening).
Prevention and control principles
Symptomatic - muscle relaxants, symptomatic treatment such as maintaining smooth breathing, debridement - removal of toxin-producing bacterial propagules, sterilization - use of sensitive antibiotics such as metronidazole, antitoxin - TIG or TAT to neutralize spasmodic toxins, passive immunity, toxoid -Specific preventive "DPT" triple vaccine for three consecutive times at 3, 4, and 5 months, and a booster at 2 and 6 years old
Clostridium perfringens
biological properties
Direct smear staining and microscopic examination of deep wound materials showed that G, large bacilli (spores are smaller than the bacterial body, located at the sub-extreme, rarely observed), with few white blood cells and atypical morphology, accompanied by other miscellaneous bacteria
Mode of infection
It is more common in war injuries, but can also be seen in trauma infections caused by work-related injuries, earthquakes, and car accidents. The conditions for traumatic infection are similar to Clostridium tetani. The incubation period is short, 8 to 48 hours. The condition deteriorates very quickly. If not treated in time, the mortality rate is high.
food poisoning
Abdominal pain, bloating, and watery diarrhea after eating contaminated food (meat); no fever, no nausea, and vomiting. Causative substances: Enterotoxin (mainly caused by type A) does not require antibiotic treatment and will heal on its own in 1-2 days.
Pathogenicity (-type A is the most important, produces alpha toxin)
Alpha toxin (phospholipase C) - breaks down membrane phospholipids, causing cell lysis, causing hemolysis, tissue necrosis, and increased vascular permeability (edema)
Collagenase, hyaluronidase, DNase - decompose and destroy cells, cause tissue necrosis, ferment sugars, produce gas, and cause emphysema
Prevention and control principles
Debridement - aggressive and thorough surgical debridement, antibiotics - immediate use of large doses of penicillin to kill pathogens, antitoxins - polyvalent antitoxins, hyperbaric oxygen - have certain effects. Local invasive surgery should be performed as early as possible to remove infected and necrotic tissue to eliminate the local anaerobic environment. If necessary, amputation should be performed to prevent the spread of lesions.
Clostridium botulinum
biological properties
Gram-positive, short bacterium, spores are tennis racket-shaped, flagellated, strictly anaerobic
Pathogenicity
Botulinum toxin - the most violent neurotoxin known, is heat-labile and is destroyed by boiling for 1 minute, A-B toxins.
Food poisoning (foodborne botulism) - clinical manifestations are mainly nerve terminal paralysis, incubation period: 1-3 days
Symptoms are early stage: fatigue, headache; blurred vision, drooping eyelids (ophthalmoplegia), difficulty swallowing and chewing, slurred speech (pharyngeal muscle paralysis), respiratory muscle paralysis is the most common cause of death, and the patient is conscious.
infant botulism
Infections from consuming honey and milk powder contaminated with bacterial spores are more common in infants under 1 year old (1-6 months old)
Symptoms are constipation, weakness in sucking milk and crying, which can progress to flaccid paralysis and respiratory arrest.
With aggressive treatment, the mortality rate is as low as 1%-2%
traumatic botulism
A very small number of secondary infections occur due to wounds or surgery. The symptoms are similar to food-borne botulism, but the incubation period is longer (4 days or longer) and the gastrointestinal symptoms are not obvious.
microbiological examination
Toxin test
food poisoning
Food (soy products, canned food, etc.), patient’s blood or feces, gastric juice
infant botulism
Baby feces or blood
wound botulism
Patient blood or wounds
Clostridium botulinum isolation and culture
food poisoning
feces, food
infant botulism
stool
wound botulism
wound specimen
treatment method
Respiratory support therapy, gastric lavage, trivalent antitoxin (A/B/E), metronidazole or penicillin treatment
Clostridium difficile
biological properties
G, Bacillus immitis, periflagellate, oval spores located in the sub-extreme strictly anaerobic state, producing yellow colonies on the cycloserine-cefoxitin-fructose agar plate, with yellow-green fluorescence under UV light. Clostridium difficile spores are highly resistant to disinfectants, antibiotics, high concentrations of oxygen and gastric acid.
Pathogenicity
Widely found in soil, various domestic and wild animals, and even human feces
Pathogenic substances
Exotoxins: Cytotoxins, leading to cell death Clostridium difficile toxin A (TcdA), Clostridium difficile toxin B (TCdA), partial production of Clostridium difficile transferase
Transmission via the fecal-oral route, resulting in Clostridium difficile infection (CDI)
clinical type
asymptomatic carriers
Iatrogenic diarrhea: Antibiotic-associated diarrhea (20%-30% is caused by Clostridium difficile) pseudomembranous colitis
microbiological examination
Isolation and culture (cannot be used as a basis)
Immunological or molecular biology methods: toxins or toxin genes
Prevention and control principles
Treatment: Stop the original antibiotics immediately.
Severe diarrhea or enteritis: metronidazole or vancomycin prophylaxis
Clostridium difficile is ubiquitous in hospitals and natural environments and is difficult to prevent. Medical staff should strictly practice aseptic procedures and use antibiotics rationally.
Spore-free anaerobic bacteria
Features
Normal flora are mainly distributed in the skin, oral cavity, upper respiratory tract, and genitourinary tract, and are 10-1000 times more common than other bacteria.
Causes opportunistic infections, often endogenous infections, and mixed infections are more common. Clinical judgment can be based on symptoms and characteristics, and microbiological examination can help diagnose
Classification by Gram-negative/Positive bacteria
Negative
Bacillus - Bacteroides fragilis, the most clinically important non-spore-forming anaerobic bacilli causing endogenous infections
Cocci - Veillonella, the main anaerobic bacteria in the throat, often one of the mixed infections
Positive
Cocci - Peptostreptococcus, mainly living in the vagina, often causing anaerobic bacteremia due to female reproductive tract infections, accounting for 1%
bacilli
Lactobacillus
Bifidobacterium - normal intestinal flora, plays an important regulatory role > Lactobacillus acidophilus and Bifidobacterium dental are related to dental caries
Infectious conditions
Changes in the host site (such as intestinal perforation), decreased host immunity, dysbiosis, anaerobic microenvironment (ischemia, hypoxia, such as tumor compression, burns, etc.)
Characteristics of infection
Endogenous infection, located throughout the body, mostly chronic and without specific disease pattern, mostly purulent infection
The secretions or pus are thick, bloody, brown-black, etc., and have a foul odor. Ineffective treatment with aminoglycoside antibiotics
Bacteria can be seen in direct smears of secretions, but no bacterial growth occurs with ordinary culture methods
Disease caused
Sepsis, central nervous system infection, oral infection, respiratory tract infection, abdominal infection, female genital tract and pelvic infection
microbiological examination
specimen collection
Collect specimens aseptically, place them in anaerobic collection bottles, and send them immediately for testing
direct smear microscopy
initial diagnosis
Isolation, culture and identification
Immediately inoculate into anaerobic culture medium to obtain pure culture. Biochemical reaction identification
Prevention and control principles
Surgical debridement to remove necrotic tissue and foreign bodies, prevent local anaerobic microenvironment, use antibiotics rationally, and select antibiotics based on drug sensitivity test results
Four bodies
spirochetes
Features
binary fission reproduction
Sensitive to multiple antibiotics
Classification
Treponema pallidum
Morphology and staining
inner flagellum
protoplast
Silver plated stained tan
dark field observation
Cultivation characteristics
Cannot grow and reproduce on inanimate artificial media
resistance
extremely weak
Particularly sensitive to temperature and drying
More sensitive to penicillin, tetracycline, and erythromycin
Pathogenic substances
capsule-like substance
adhesion factor
Invasive enzymes
Disease caused
acquired syphilis
Stage I: painless chancre, which can heal spontaneously in 1-2 months
Stage II: Syphilis rash appears on the skin and mucous membranes all over the body, which can heal on its own in 3 weeks to 3 months.
Stage III: Systemic syphilis damage appears 2-7 years later, mainly nodular syphilis rash and gumma
Leptospira
Morphology and staining
inner flagellum
Cylindrical protoplast
Silver plating is dyed golden yellow or tan
dark field observation
Cultivation characteristics
korthof medium
resistance
Weak, can survive for several months in neutral moist soil or water
Pathogenic substances
Adhesin
endotoxin
Hemolysin
Invasive enzymes
Disease caused
Leptospiraemia
Cold, heat, soreness, fatigue, red eyes, headache, swollen lymph nodes, severe gastrocnemius muscle pain, is a zoonotic disease
Borrelia burgdorferi
Morphology and staining
inner flagellum
outer protein
Silver stain, Giemsa or Wright stain
Cultivation characteristics
High nutritional requirements and slow growth
resistance
Weak, allergic to penicillins, cephalosporins, and erythromycin
Pathogenic substances
OspA
ikB
endotoxin-like substances
Disease caused
Lyme disease
erythema migrans, arthritis
Late stages include chronic arthritis, nervous system and skin abnormalities, and endocarditis.
The vector is Ixodes
Mycoplasma
Features
lack of cell wall
The smallest prokaryotic microorganism that can pass through a bacterial filter and grow and reproduce in a non-living medium
form and structure
top structure
cholesterol
subtopic
Cultivation characteristics
binary fission reproduction
“Omelette”-like colonies
resistance
Weak, not sensitive to penicillin
Pathogenic substances
Adhesin
biofilm
toxic metabolites
lipoprotein
Classification
Mycoplasma pneumoniae
Droplet transmission, frequent in late summer and early autumn, infection can cause interstitial pneumonia/primary atypical pneumonia
Ureaplasma
Sexually transmitted infection can cause urethritis, cervicitis, pelvic inflammatory disease, etc.
Chlamydia
Features
Strictly parasitic within eukaryotic cells, has a unique development cycle, and can pass through bacteria filters
binary fission reproduction
independent enzyme system
allergic to multiple antibiotics
Biological traits
Primarch
Small, dense, and contagious
reticular body
Large, loose, non-infectious
Cultivation characteristics
Obligate intracellular parasite, reproduces in the yolk sac of chicken embryos
resistance
Resistant to cold but not heat, can be quickly inactivated by ultraviolet irradiation, sensitive to erythromycin, doxycycline, chloramphenicol, and tetracycline
Classification
Chlamydia trachomatis
Trachoma (eye-hand-eye infection)
Inclusion conjunctivitis (birth canal infection)
Urogenital tract infection (sexual contact infection)
Pneumonia in infants and young children (D-K serum infection)
Lymphogranuloma venereum (sexual contact infection)
Chlamydia pneumoniae
Droplet transmission can cause coronary heart disease, atherosclerosis and other diseases. Cellular immunity is the main anti-infection, and immunity is not long-lasting.
Rickettsia
Features
Strictly intracellular parasitism
Using arthropods as communication media
Sensitive to multiple antibiotics
Morphology and staining
Various shapes, mainly club-shaped or rod-shaped
Commonly used Giemsa staining methods
Cultivation characteristics
binary fission reproduction
Chicken embryo egg sac culture method, animal inoculation method
resistance
Weak, sensitive to chloramphenicol and tetracycline antibiotics
Pathogenic substances
Adhesins OmpA and OmpB
Phospholipase A
Classification
Rickettsia prowazekii/epidemic typhus
lice-human-lice
Rickettsia typhus/endemic typhus
Rat-Flea-Human
Orientia scrub typhus/scrub typhus
Rat-Chigger-Human
treat
Antibiotics (tetracyclines) (sulfonamides prohibited)