Exam prep

naming bacteria from microscope - gram stain, shape, clusters/chains/pairs/singular

to know for each bacteria: gram stain result, diagnostic features, infections caused (pictures to identify - boil, impetigo, scaled skin syndrome, folliculitis, toxic shock syndrome, electron micrograph of staphylococcal biofilm. learn signs symptoms, which cohort of people, complications)

different types of media (enriched) and their uses. bacteria features on the agar. Blood agar: difference between S, aureus and S. epidermis

Mannitol salt agar: distinguish between coagulase positive from negative. It is selective because of the salt. Staphylococci tolerates high levels of salt. Differential die to mannitol sugar. S, aureus ferments alcohol. pink and no fermentation means not staph aureus.

MacConkey agar: selective (gram negative due to bile salts) differential ( due to lactose → pink doesn’t ferment lactose → stays yellow). Yellow tint

Nutrient agar: basal medium (supports growth of most bacteria). listeria streptococci don’t grow

coagulase tests: description of its parthenogenesis what toxins are involved, impact of toxins, virulence factor. biological role of coagulase (enzyme that converts fibrinogen to fibrin) S. aureus: diagnostic test because it produces coagulase. slide: latex particles flocculate due to recombinant that are immobilized onto latex particles

learn streptococcal diseases: streptococcal throat, cellulitis, erysipelas, necrotizing fascistic. How is it diagnosed/managed. How are the infections manages: name antibiotic and mode of actions and class, broad/narrow spectrum

antibiotic susceptibility → disk diffusion test, MIC test using E test. Saprophyticus is a UTI in sexually active women

staphylococci: characteristic and how they appear

differentiate between staphylococci and streptococci (gram + cocci is chains or pairs. Disk diffusion test: optochin susceptibility. S. pneumoniae susceptible, viridians streptococci resistant)

differentiate strep. pneumoniae (gram + cocci in pairs) from other streptococci

Hemolytic patterns on blood agar. Group A strep → S. pyogenes beta-hemolysis on blood agar. Susceptible to basa trasin. Alpha (green - partial hemolysis) beta (complete hemolysis. put agar to light to look through)

Alpha hemolytic streptococci: clinical significance. Normal flora to mouth( can cause infection is in a non sterile sight e.g. Strep. pneumonia, ineffective endocarditis, lobar pneumonia

Enterococci: gram + cocci in short chains in GIT. infections associated e.g. UTI, effective endocarditis. grow on MacConkey agar. Small magenta colored colonies