CLINICAL MICROBIOLOGY

Question 1

Aminoglycosides - Drug names and mode of action

Answer 1

inhibits protein synthesis (bacterocidal)
ex. gentamicin, amikacin tobramycin, streptomycin kanamycin

Question 2

Beta-lactams / Cephalosporins

Answer 2

Inhibits cell wall synthesis (bacterocidal)
ex. Penicillin, Amoxicillin, Cloxacillin, methicillin, Oxacilln, Piperacillin
* Cefazolin (1G)
* Cefuroxime (2G)
* Ceftazidime (3G)
* Ceftriaxone (3G)

Question 3

Glycopeptides

Answer 3

Inhibits cell wall synthesis, inhibits gram POS and is Bacterocidal
Ex. Vancomycin

Question 4

Fluoroquinolones

Answer 4

Inhibits DNA and RNA synthesis, bacterocidal
Ciprofloxacin, levofloxacin, moxifloxacin

Question 5

Lincosamides * ano2

Answer 5

Inhibits protein synthesis –bacterostatic
Clindamycin

Question 6

Tetracyclines

Answer 6

Inhibits RNA synthesis- bacteriostatic
Doxycycline, Minocycline, Tetracycline

Question 7

Sulfonamides

Answer 7

Inhibits folic acid synthesis - bacterostatic
Sulfamethoxazole/ trimethoprim

Question 8

What is the purpose of ESBL?

Answer 8

Used to detect cephalosporin resistance in Escherichia coli and Klebsiella pneumonia

Question 9

Obligate anaerobes

Answer 9

cannot use oxygen for growth and are harmed by it

Question 10

Aerotolerant organisms

Answer 10

cannot use oxygen for growth, but tolerate its presence

Question 11

Facultative anaerobes

Answer 11

can grow without oxygen, but if present can utilize it

Question 12

What is BAK?

Answer 12

Brucella Agar with hemin, vitamin K and 5% sheep blood
Enriched non selective media that’s used for isolation and to exhibit hemolysis

Question 13

What is PEA?

Answer 13

Used as selective media for gram positive organisms

Question 14

What is LKV?

Answer 14

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)

Question 15

What is BBE media?

Answer 15

used to isolate Bacteroids fragilis group, selective and differential media, contains 20% bile, esculin and kanamycin

Question 16

Egg Yolk Agar

Answer 16

Used for clostridium based on lecithinase and lipase production

Question 17

Clostridium species

Answer 17

Large +B w/ spores, R-CAMP and lecithinase negative
Except C.Perfringes are positive

Question 18

What is TSI media composed of?

Answer 18

0.1% dextrose, 1% lactose and 1% sucrose, phenol red, sodium thiosulfate, ferrous sulphate, peptones, NaCl, agar and H2O

Question 19

What is Basal medium?

Answer 19

Supplies basic or minimum growth requirements and is nonselective
ex. nutrient agar

Question 20

What is an enriched medium?

Answer 20

Medium that contains additional substances to meet nutrient requirements of certain bacteria and is nonselective
ex. BA,CA

Question 21

What is selective medium?

Answer 21

Medium that contains substances that inhibit or suppress growth of certain organisms while permitting other ones to grow
ex. PEA

Question 22

What is differential medium?

Answer 22

Medium that contains substances that would help distinguish between two or more types of bacteria without inhibiting their growth
ex. mannitol salt agar

Question 23

What is BCYE used for?

Answer 23

growth of Legionella

Question 24

What is MAC agar?

Answer 24

It is selective and differential, bile salts inhibit some gram + and fastidious gram -, lactose &neutral red are differential

Question 25

What are the primary infections caused by S.pyogenes?

Answer 25

Impetigo, strep throat, scarlet fever, necrotizing fasciitis, septicemia

Question 26

What infections is S.agalactiae known for?

Answer 26

May cause meningitis, septicaemia and pneumonia in neonates -prenatal screening for women @37 weeks

Question 27

What infections do Grp C and G strep cause?

Answer 27

Similar to A and B except they're acute and usually involve compromised patients

Question 28

What infections is Strep pneumonia known for?

Answer 28

Leading cause of meningitis, may also cause pneumonia, otitis media and conjunctivitis

Question 29

What infections is Strep viridians group known for?

Answer 29

Common cause of SBE (subacute bacterial endocarditis), may also cause bacteremia in immunocompromised patients

Question 30

What infections is Enterococcus group known for?

Answer 30

Most infections are nosocomial and include UTI, bacteremia, endocarditis and wound infections

Question 31

What infections is Bacillus cereus known for?

Answer 31

"fried rice disease" where spores are ingested and the enterotoxins cause a self limiting food poisoning

Question 32

What infections is Listeria monocytogenes known for?

Answer 32

Generally causes food borne illness, can cause intrauterine infections, meningitis of immunocompromised hosts

Question 33

What infections is Bordetella pertussis known for?

Answer 33

whooping cough

Question 34

What is the consequence of underfilling a blood culture bottle?

Answer 34

False negatives

Question 35

What volume of urine should be culture for a nephrostomy urine?

Answer 35

0.1ml

Question 36

How long should a biphasic blood culture for Brucella spp. be incubated?

Answer 36

4 weeks

Question 37

Why is gelatin important to Neisseria gonorrhoea in blood cultures?

Answer 37

It protects from SPS toxicity

Question 38

What organism is most typically associated with fungemia?

Answer 38

Candida albicans

Question 39

What organism when grown in a blood may be associated with a neoplasm?

Answer 39

Clostridium septicum

Question 40

What are the signs and symptoms of septicemia?

Answer 40

Fever, chills, hyperventilation, diarrhea

Question 41

What is septicemia?

Answer 41

When bacterial toxins harm the host

Question 42

What eye infections are diabetic patients prone to?

Answer 42

orbital mucormycosis

Question 43

What is a fistula?

Answer 43

Abnormal passage from organ to organ or body surface

Question 44

What media are used to isolate Corynebacterium diphtheriae?

Answer 44

BYCE and Regan-Lowe

Question 45

What best describes an atmosphere with 5-10% CO2 and 15% O2?

Answer 45

Environment where facultative anaerobes grow

Question 46

What is the smallest size of particles removed by a HEPA filter?

Answer 46

0.3 microns