CLINICAL MICROBIOLOGY Flashcards
Aminoglycosides - Drug names and mode of action
inhibits protein synthesis (bacterocidal)
ex. gentamicin, amikacin tobramycin, streptomycin kanamycin
Beta-lactams / Cephalosporins
Inhibits cell wall synthesis (bacterocidal)
ex. Penicillin, Amoxicillin, Cloxacillin, methicillin, Oxacilln, Piperacillin
* Cefazolin (1G)
* Cefuroxime (2G)
* Ceftazidime (3G)
* Ceftriaxone (3G)
Glycopeptides
Inhibits cell wall synthesis, inhibits gram POS and is Bacterocidal
Ex. Vancomycin
Fluoroquinolones
Inhibits DNA and RNA synthesis, bacterocidal
Ciprofloxacin, levofloxacin, moxifloxacin
Lincosamides * ano2
Inhibits protein synthesis –bacterostatic
Clindamycin
Tetracyclines
Inhibits RNA synthesis- bacteriostatic
Doxycycline, Minocycline, Tetracycline
Sulfonamides
Inhibits folic acid synthesis - bacterostatic
Sulfamethoxazole/ trimethoprim
What is the purpose of ESBL?
Used to detect cephalosporin resistance in Escherichia coli and Klebsiella pneumonia
Obligate anaerobes
cannot use oxygen for growth and are harmed by it
Aerotolerant organisms
cannot use oxygen for growth, but tolerate its presence
Facultative anaerobes
can grow without oxygen, but if present can utilize it
What is BAK?
Brucella Agar with hemin, vitamin K and 5% sheep blood
Enriched non selective media that’s used for isolation and to exhibit hemolysis
What is PEA?
Used as selective media for gram positive organisms
What is LKV?
Used to isolate anaerobic gram negative bacilli
Contains lakes blood (provides additional growth factors), vancomycin (inhibits gram positive organisms), kanamycin (inhibits some gram negative organisms)
What is BBE media?
used to isolate Bacteroids fragilis group, selective and differential media, contains 20% bile, esculin and kanamycin
Egg Yolk Agar
Used for clostridium based on lecithinase and lipase production
Clostridium species
Large +B w/ spores, R-CAMP and lecithinase negative
Except C.Perfringes are positive
What is TSI media composed of?
0.1% dextrose, 1% lactose and 1% sucrose, phenol red, sodium thiosulfate, ferrous sulphate, peptones, NaCl, agar and H2O
What is Basal medium?
Supplies basic or minimum growth requirements and is nonselective
ex. nutrient agar
What is an enriched medium?
Medium that contains additional substances to meet nutrient requirements of certain bacteria and is nonselective
ex. BA,CA
What is selective medium?
Medium that contains substances that inhibit or suppress growth of certain organisms while permitting other ones to grow
ex. PEA
What is differential medium?
Medium that contains substances that would help distinguish between two or more types of bacteria without inhibiting their growth
ex. mannitol salt agar
What is BCYE used for?
growth of Legionella
What is MAC agar?
It is selective and differential, bile salts inhibit some gram + and fastidious gram -, lactose &neutral red are differential
What are the primary infections caused by S.pyogenes?
Impetigo, strep throat, scarlet fever, necrotizing fasciitis, septicemia
What infections is S.agalactiae known for?
May cause meningitis, septicaemia and pneumonia in neonates
-prenatal screening for women @37 weeks
What infections do Grp C and G strep cause?
Similar to A and B except they’re acute and usually involve compromised patients
What infections is Strep pneumonia known for?
Leading cause of meningitis, may also cause pneumonia, otitis media and conjunctivitis
What infections is Strep viridians group known for?
Common cause of SBE (subacute bacterial endocarditis), may also cause bacteremia in immunocompromised patients
What infections is Enterococcus group known for?
Most infections are nosocomial and include UTI, bacteremia, endocarditis and wound infections
What infections is Bacillus cereus known for?
“fried rice disease” where spores are ingested and the enterotoxins cause a self limiting food poisoning
What infections is Listeria monocytogenes known for?
Generally causes food borne illness, can cause intrauterine infections, meningitis of immunocompromised hosts
What infections is Bordetella pertussis known for?
whooping cough
What is the consequence of underfilling a blood culture bottle?
False negatives
What volume of urine should be culture for a nephrostomy urine?
0.1ml
How long should a biphasic blood culture for Brucella spp. be incubated?
4 weeks
Why is gelatin important to Neisseria gonorrhoea in blood cultures?
It protects from SPS toxicity
What organism is most typically associated with fungemia?
Candida albicans
What organism when grown in a blood may be associated with a neoplasm?
Clostridium septicum
What are the signs and symptoms of septicemia?
Fever, chills, hyperventilation, diarrhea
What is septicemia?
When bacterial toxins harm the host
What eye infections are diabetic patients prone to?
orbital mucormycosis
What is a fistula?
Abnormal passage from organ to organ or body surface
What media are used to isolate Corynebacterium diphtheriae?
BYCE and Regan-Lowe
What best describes an atmosphere with 5-10% CO2 and 15% O2?
Environment where facultative anaerobes grow
What is the smallest size of particles removed by a HEPA filter?
0.3 microns
