MLT 259 Micro Study Guide

Question 1

Collection and transporting of specimens (i.e. urines)

Answer 1

write name, date, initials
midstream clean catch
transport in sterile cup, asap

Question 2

What test differentiates Staphylococcus aureus from non-pathogenic staphylococcus?

Answer 2

coagulase

Question 3

Principle of the catalase test.

Answer 3

to differentitate staph spp from strep spp.

place 1mL of 3% solution of hydrogen peroxide on slide and add the organism; bubbles is positive

Question 4

What test is used to distinguish the coliform bacteria from the enteric pathogens?

Answer 4

TSI- triple sugar iron agar
pathogens are generally non-lactose fermenters
6.5% NaCl

Question 5

Collection and transport of anaerobic specimens. What type of collection system is not suitable for anaerobic cultures?

Answer 5

routine swabs

Question 6

How could you differentiate Listeris monocytogenes from Corynebacterium sp. (diphtheroids)?

Answer 6

Motility
L. mono + umbrella
C. diph =

CAMP
L. mom +
C. diph =

Question 7

How could you differentiate alpha strep from step pneumonia?

Answer 7

Step. peumo is “p” disk + optochin

other strep spp are negative

Question 8

What agar is used for Kirby-Bauer sensitivity testing?

Answer 8

Mueller-Hinton

Question 9

Which enteric pathogen would be least likely to survive if the stool if left at room temp for an extended period of if the stool is refrigerated?

Answer 9

Shigella

Question 10

Organisms that cause foo poisoning, or infection.

Answer 10

Campylobacter
E. coli
Shigella
Salmonella
S. aureus

Question 11

What organism is gram =, motile, oxidase + rod with a grape-like odor?

Answer 11

Pseudomonas aeruginosa

Question 12

Which genus contains chromogenic, gram = motile rods which have ben implicated in septicemia, pulmonary and urinary tract infections?

Answer 12

Serratia

Question 13

What is the most common organism in the human intestines?

Answer 13

Bacteroides sp.

Question 14

Which genus and species is best cultured in an alkaline peptone medium and causes a severe type of diarrhea producing rice water stools?

Answer 14

Vibrio cholera

Question 15

To which Lancefield group do most of the human pathogens which are beta hemolytic streptococci belong?

Answer 15

Group A

Question 16

How do you differentiate genus Enterobacter from the genus Klebsiella?

Answer 16

Motility
Kleb =
Entero +

Question 17

Interpret TSI reactions

Answer 17

k/k, alka/alka, non-fermentor
k/a alka/acid, glucose fermentor only
a/a acid/acid, lactose & or sucrose fermenters
bubbles H2S gas production

Question 18

How do gram positive and gram negative bacteria differ?

Answer 18

GP has thick layer of peptidoglycans in their cell walls yet lack outer membrane, stain purple

GN has thin layer of peptidoglycans and an outer membrane around cell wall, stain pink

Question 19

The “satellite phenomenon” indicated that staphylococci produce which factor?

Answer 19

V factor

Question 20

What is beta-lactamase?

Answer 20

enzyme produced by bacteria to resist/inhibit antibiotics (pencillins)

Question 21

What sugar is fermented by all Enterbacteriaceae?

Answer 21

glucose

Question 22

Meningitis due to Hemophilus influenza is most common in which age group?

Answer 22

infants and young children

3months - 6 years

Question 23

Which genera of Enterobacteriaceae are non-motile?

Answer 23

Kelbsiella

Shigella

Question 24

Which genera of Enterobacteriaceae are resistant to many antibiotics and are frequently found in nonsocomial infections?

Answer 24

Serratia

Proteus

Question 25

Which organism is most frequently isolated from a cat or dog bite?

Answer 25

Pasteuralla multocida

Question 26

From what type of specimen are members of the genus Lactobacillus isolated?

Answer 26

GI tract vagina urine

Question 27

What steps must be take to identify Campylobacter in the laboratory?

Answer 27

use campy plate incubate 42 in CO2 oxidase + gs shows bent rods "seagulls"

Question 28

Why are antibiotics added to mayer-martin media?

Answer 28

To inhibit growth of normal commensal organisms vancomycin-inhibits GP nystatin-inhibits fungi colistin-inhibits GN

Question 29

What are facultative organisms?

Answer 29

microorganisms that grow aerobically or anareobically

Question 30

In the performance of a gram stain, what effect would omitting the iodine step have on the final color of gram + and gram = organisms?

Answer 30

Crystal violet would not adhere to the cells and would stain pink

Question 31

Which organisms can be normal in the upper respiratory tract?

Answer 31

.

Question 32

Which sterilization method utilizing heat is the most effective and useful for the clinical lab?

Answer 32

steam autoclave

Question 33

Which organism could young Staphylococcus growing on SBA be confused with?

Answer 33

Group A strep

Question 34

Appearance of Neisseria gonorrhoeae in a uretheral smear.

Answer 34

intracellular GN coffee bean shaped diplococci

Question 35

If organisms are seen on a direct gram stained smear but are not recovered on routine culture, what type of organism is implicated?

Answer 35

anaerobes

Question 36

Which body fluid is often cultured in an effort to trace Salmonella typhi carriers?

Answer 36

bile

Question 37

What is the appearance of an encapsulated organism on blood agar and what effect does the capsule have on the organism's virulence?

Answer 37

mucoid | increased virulence

Question 38

**Principle of the decarboxylase test.

Answer 38

p/p + | p/y =

Question 39

Define MIC.

Answer 39

Minimum inhibitory concentration. lowest concentration on antimicrobial that inhibits bacterial growth

Question 40

Incubation conditions for anaerobic cultures.

Answer 40

no oxygen (bio-bag) placed in gas pak providing CO2 at 36 degreesC on anaerobic media

Question 41

What terms are used to describe the morphology of the members of the genus Corynebacterium?

Answer 41

Chinese letters picket fence palisade diphteroids

Question 42

Characteristics of bacterial spores.

Answer 42

hard, thick walled capsule dormant non-reproductive

Question 43

Interpret reactions of XLD.

Answer 43

highly selective, differential media Salmonella- red colonies with black centers, H2S production Shigella- red colonies yellow + lactose

Question 44

Biochemical characteristics of E. coli

Answer 44

lactose fermenters indole + methyl red + urea, H2S =

Question 45

Appearance and pathogenicity of Klebsiella pneumonia.

Answer 45

large, pink, mucoid, stringy colonies on MAC

Question 46

What screening test is used in the laboratory to differentiate E. coli 0157:H from normal strains of E. coli?

Answer 46

latex agglutination typing | MAC w/ sorbitol

Question 47

What test can be used to differentiate the two species of Proteus?

Answer 47

Indole P. vulgaris + P. mirabilis =

Question 48

Which species might be considered as contaminants if they were isolated from a blood culture?

Answer 48

S. epidermidis Diphtherioids Bacillus sp

Question 49

If two organisms are to be used as quality control organisms for a particular test or procedure, should their reactions be the same or different?

Answer 49

Different; one should demonstrate + rxns, and the other = rxns

Question 50

What are the designations for the cell wall, flagellar and capsular antigens in bacteria? Which antigen can mask the cell wall antigen in serological typing?

Answer 50

O-cell wall H-flagella V or Ki-capsule; mask cell wall

Question 51

The safety hood should be used for which procedures in the microbiology laboratory?

Answer 51

respiratory, fungal, AFB, stool cultures

Question 52

What characteristics of a specimen might cause you to suspect an anaerobe and on what type of laboratory media should such a culture be inoculated?

Answer 52

noticeable strong odor, from deep wound or abscess | SBA, MAC, CHOC, PEA, ANABLD, ANA/KV, ANA/PEA, THIO

Question 53

What is the gram stain morphology of Bacteroides and Fusobacterium?

Answer 53

Bacteroides; GNR with rounded ends, pleomorphic | Fusobacterium; GNR with pointed ends

Question 54

What types of specimens are suitable for anaerobic cultures? Which are unsuitable?

Answer 54

deep wounds, abscess, tissue, blood, trans-tracheal aspirate, sterile body fluid, supra pubic urine NOT OK- anything in contact with O2, urine, stool, sputum

Question 55

What is the gram stain morphology of Neisseria meningitides and what sugars are utilized by this organism?

Answer 55

GNDC coffee bean shaped | glucose and maltose

Question 56

What stains are used for staining members of the genus Mycobacterium?

Answer 56

Ziehl-Neelsen

Question 57

Why is N-acetyl-L-cysteine the most common agent used for sputum concentration for AFB cultures?

Answer 57

it breaks up the specimen and enhances the recovery of Mycobacterium; destroys NF; good recovery

Question 58

What is the colonial morphology of Mycobacterium tuberculosis on Lowenstein-Jensen medium?

Answer 58

rough, tough appearance, buff color, fuzzy, heaped up

Question 59

What can be used as a clearing agent to remove protein material from a mycology specimen?

Answer 59

KOH

Question 60

What is the procedure of choice for the demonstration of Cryptococcus in CSF?

Answer 60

India Ink

Question 61

What is the best single medium for the primary isolation of fungi?

Answer 61

Sabouraud's/SDA

Question 62

What are the growth characteristics and other identifying characteristics of Candida albicans?

Answer 62

germ tube + budding yeast pseudohyphae creamy white colonies

Question 63

What is the morphology of members of the genus Aspergillia, the genus Penicillium and the genus Rhizopus?

Answer 63

dandelion skeletal hand non-septate

Question 64

What stage in the development of a parasite is best demonstrated by a permanent stained smear?

Answer 64

troph

Question 65

Which method of concentrating stool specimens is best for which parasites?

Answer 65

Flotation; nematode, cestode eggs, coccidian oocysts | sedimentation; trematode eggs, operculated-they sink in flotation

Question 66

What is the appearance of the cyst of Entamoeba histolytica?

Answer 66

mature has 4 nuclei, immature has fewer central karyosome, even staining peripheral chromatin, cigar shaped

Question 67

What is the microscopic appearance of the troph Giardia lamblia?

Answer 67

medium size, pear-shaped 2 nuclei axonomes down middle of body 4 pairs of flagella

Question 68

How can you differentiate the various species of Plasmodium?

Answer 68

P. falciparum; schizont 8-36 merozoites "applique" | P. malariae; troph has band, schizont 6-12 merozoites

Question 69

Biochemical reactions of Staphylococcus epidermidis.

Answer 69

catalase + | coagulase =

Question 70

Which genera are oxidase positive?

Answer 70

Pseudomonas Neisseria Campylobacter

Question 71

Rapid Methods for identification on Enterobacteriaceae.

Answer 71

API Enterotube Micro-ID - 4 hours Minitek

Question 72

Which growth factors are required by the various Hemophilius species?

Answer 72

X, V

Question 73

Which fungi are dimorphic?

Answer 73

``` Blastomyces dermatidis Coccidiodes imitis Histoplasma capsulatum Paracoccidiodes braziliensis Sporothrix shenckii ```