Bacteriology 6: Staphylococci Flashcards
What are bacteria groups based on?
The type of inflammation they induce
What type of inflammation do pyogenic bacteria form?
- Puss forming
- Acute inflammation
- See predominantly neutrophils
What type of inflammation do pyogranulomatous bacteria form?
Mixture of acute and chronic inflammation
- We will see a mixture of cells
–Polymorphonuclear neutrophils
– Macrophages
– Lymphocytes
– + or - eosinophils if fungal
What type of inflammation do Granulomatous bacteria form?
We see central necrosis surrounded by:
- giant epitheliod cells (activated macrophages)
- macrophages
- lymphocytes
- Granulocytes
- Thick fibrous capsule
What type of inflammation do necrotizing bacteria form?
We see a lot of cellular debris:
- Toxic cells
- Inflammatory cells
- the causative bacteria
What are the types of Gram + cocci bacteria we are discussing?
- Staphylococci
- Streptococci
What are types of pyogenic bacteria?
- Staphylococci (gm+ cocci)
- Streptococci (gm+ cocci)
- Trueperella (gm+ rods)
- Corynebacterium (gm+ rods)
What are the types of gram + rods?
Clostridium
Actinomyces
Nocardia
Dermatophilus
Rhodococcus
Trueperella
Corynebacterium
Mycobacteria
What are types of pyogranulomatous bacteria?
- Staphylococci (gm+ cocci)
- Actinomyces (gm+ rods)
- Nocardia (gm+ rods)
- Dermatophilus (gm+ rods)
- Rhodococcus (gm+ rods)
What are types of granulomatous bacteria?
Mycobacteria (gm+ rods)
What are types of necrotizing bacteria?
Clostridium (gm+ rods)
Where do pyogenic bacteria cause dx?
Extracellular
What are hallmarks of inflammation?
- Increased number of cells in fluid
- Increased number of protein in fluid
What is coagulase test meaning?
- It differentiates between weakly virulent and highly virulent
+ mean highly virulent - mean weakly virulent
Where are coagulase positive staphylococci found?
Skin mucocutaneous junctions
Distal nasal passage
External nares
Rectum
Where are coagulase negative staphylococci found?
skin- normal flora
Factors helping staphylococci be good pathogens
Capsule or pseudocapsule
Exotoxins- Leukotoxins and hemolysins
Intracellular survival
Biofilm survival
How does the capsule help cause disease?
- Anti-phagocytic
Non-pathogenic (coag-neg) staphylococci interaction with macrophages?
Macrophages can easily phagocytize coag-neg staphylococci
How do exotoxins help cause disease?
Many different exotoxin
Hemolysins and leukotoxins are important for virulence
—- These are cytotoxic and lethal (aka damage cells)
—- Leukotoxins kills phagocytes therefore assist in evading the immune system
How does being a facultative intracellular bacteria assist in causing disease
Evade the immune system by:
- Killing phagocytes
- avoid antibodies
- avoiding abx that act extracellular
What kind of infection can facultative intercellular bacteria cause?
PI - chronic
What kind of pathogen are staphylococci?
Opportunistic pathogens: require compromise for host-pathogen interaction
Are any staphylococci pathognomic?
No
diseases caused by staphylococci?
Pyoderma (VERY common)
Mastitis
Greasy pig disease (Exudate dermatitis)
Musculoskeletal infections: Osteomyelitis, Septic arthritis
Urogenital tract infections: Cystitis, Prostatitis
What rules are you supposed to follow in diagnosing staphylococci?
Part of normal flora in sterile site so follow four point rule:
- the sample must be collected in appropriate fashion from site of infection
- there must be evidence of inflammation in the sample
- good if there is evidence of bacteria in the sample
- the bacteria isolate must have the opportunity and be capable of causing this dx
