Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
15 Cards in this Set
- Front
- Back
|
Classification of Medically important cocci |
gram positive- staphylococcus, streptococcus, enterococcus gram negative- neisseria |
|
|
Staphylococcus |
Gram positive in clusters, 1 um in diameter Facultative anaerobic High salt tolerance- can grow on mannitol salt agar plate Catalase positive- will bubble with hydrogen peroxide |
|
|
Classification of staphylococcus |
coagulase test- positive shows clotting when blood plasma added to bacteria in test tubes, no reaction for negative positive- S. aureus negative- S. epidermidis, S. saprophyticus |
|
|
S. epidermis |
adheres to prosthetics (implants, catheters) causing prosthesis infection |
|
|
S. saprophyticus |
causes acute cystitis, a UTI, in young women |
|
|
S. aureus- virulence factors for attachment |
teichoic acid on membrane (only found in Gram positive bacteria) |
|
|
S. aureus virulence factors for evasion of host defence |
* Coagulase, converting fibrinogen to fibrin
* Protein A, anti-phagocytic, reacts with the constant region (Fc) of IgG, meaning that the usual variable region which would allow the antibody to work on the bacteria cannot attach to it * Catalase |
|
|
S. aureus virulence factors for invasion |
* Hyaluronidase, lipase, DNase, protease…
|
|
|
S. aureus virulence factors... toxins |
* Epidermolytic toxins- causes lysis of skin cells, e.g. scalded skin syndrome
* Toxic shock syndrome toxin * Enterotoxins- acts on GI tract causing food poisoning * Panton-Valentine Leukocidin- acts on skin, dermonecrotic |
|
|
Pyogenic diseases caused by S. aureus |
Skin and soft tissue- e.g. folliculitis, which if S. aureus travels deeper into skin, worsens into furuncles Osteomyelitis- inflammation of bone / bone marrow Arthritis Pneumonia Infective endocarditis |
|
|
Toxin mediated diseases caused by S. aureus |
Scalded skin syndrome Toxic shock syndrome Food poisoning |
|
|
Antibiotic sensitivity of S. aureus |
Penicillin- yet now most S. aureus produce penicillinase, causing resistance Methicillin and cloxacillin are alternatives, unaffected by penicillinase- yet growing MRSA Vancomycin is another alternative, yet VRSA |
|
|
Neisseria |
Gram negative diplococci Strictly aerobic Two important species- N. meningitides (meningococcus) and N. gonorrhoeae (gonococcus) Enzyme cytochrome oxidase found on membrane- turns oxidase reagent strips purple |
|
|
Virulence factors of Neisseria |
* Pili or fimbriae for attachment
* Capsule (in N. meningitidis), antiphagocytic * Lipo-oligosaccharide is an endotoxin produced, which causes fevers |
|
|
Neisseria gonorrhoeae clinical diseases |
* Urethritis in men (can be confirmed by swabbing pus produced, and looking under microscope after Gram staining)
* Endocervicitis in women * Pelvic inflammatory disease (uterus, fallopian tubes, ovaries) * Proctitis (infection of the rectum due to anal sex) * Pharyngitis (infection of the pharynx due to oral sex) * Gonococcal ophthalmia neonatorum (infection of eyes of babies after passing through infected mother’s birth canal) * Disseminated gonococcal infection * Arthritis (uncommon) |
