Micro Final

Which of the following statements concerning beta lactamase is false:

Negative test for beta-lactamase always correlates with sensitivity to Gentamicin

The ratio of the amount of antimicrobial that is toxic to the amount, which is effective, is known as:

therapeutic index

The enzyme that breaks penicillin into penicilloic acid is:

Beta lactamase

Antibiotics that act by inhibiting synthesis of the bacterial cell wall include:

Penicillin, methicillin, cephalosporins

A positive beta-lactamase test indicates:

Resistance to penicillin

A procedure, which directly determines beta-lactamase production by a microorganism, is based on the
detection of:

Color change resulting from the breaking of beta-lactam ruing of a chromogenic cephalosporin

The initial site of infection with Cryptococcus neoformans is:

Pulmonary

Which of the following organisms is identified by its ability to produce germ tubes in plasma at 37
degrees C in 2 hours:

Candida albicans

A yeast with a capsule seen on an India Ink prep of spinal fluid may be:

Cryptococcus neoformans

Candida albicans is part of the normal flora of which of the following sites?

Throat, vagina, intestinal tract

Which of the following are useful in identifying Candida albicans?

Germ tube positive, urease negative

The most common cause of bacterial meningitis in children 1-4 is:

Haemophilus influenzae

Haemophilus influenzae will grow on:

BAP with a V strip, Chocolate agar

X factor corresponds to which growth factor

Hemin

Haemophilus aegyptius differs most strikingly from Hemophilus influenzae in:

The disease it causes

Hemophilus influenzae:

Grows better on chocolate agar than blood agar

The satellite phenomenon is associated with:

Hemophilus influenzae

The most important cause of meningitis and epiglottis in children, some strains having become resistant
to the drug of choice (ampicillin) by means of beta-lactamase enzyme is:

Hemophilus influenzae

You have isolated a gram-negative coccobacillus from an eye culture from a case of conjunctivitis. The
organism grows well on chocolate agar but not on blood agar, and further testing show it requires both
the X and V factors for growth. The organism is most likely:

H. aegypticus

The porphyrin test is used to identify an organism's requirement for:

Factor x

The routine medium used for isolation of Hemophilus species is:

Chocolate agar

The role of normal skin flora is to:

Compete for attachment sites with pathogens, thus decreasing available sites for pathogens

The collection of organisms referred to as "diptheroids" are:

Normal flora of the skin, gram-positive rods

Which of the following organisms causes furuncles and carbuncles?

S. aureus

Furuncles and carbuncles are abscesses usually caused by:

S. aureus

A specimen from a wound is sent to the laboratory for routine culture. Select the most appropriate
method for processing of this specimen.

Direct Gram stain smear, plate on BAP, Choc, and MAC

A satellite test is performed to speciate Hemophilus spp, using BAP. After 24 hours the organism is seen
growing around Staph on both BAP. This means the organism requires:

NAD

Hemophilus aegyptius is primarily a pathogen of the:

Eye

Hemophilus influenzae is most commonly encountered as a pathogen in:

Children and elderly

The satellite phenomenon works on the following principles:

Staphylococcus aureus supplies the coenzyme NAD; the blood agar supplies the X factor

Hemophilus parainfluenzae requires which growth factors:

V factor

Normal flora of the skin consists of:

Staph species, alpha-hemolytic Streptococcus sp., Corynebacterium sp.

Skin:

Contains expected flora

The minimal identification information needed to identify a yeast isolate as Candida albicans would be:

Positive germ tube test

A presumptive identification of Cryptococcus neoformans depends on which of the following results?

Negative germ tube, positive urease

The gram stain morphology of the genus Hemophilus is best described as:

Gram negative coccobacilli

Impetigo is most often caused by:

Gp A Strep

Bordet-Gengou media is used for the laboratory diagnosis of:

Whooping cough

The specimen of choice to collect for Bordetella pertussis is:

Nasopharyngeal swab

Pertussis continues to be a problem of worldwide importance. Children under the age of 2 primarily
acquire the disease by:

Coming in contact with infected adults who have pertussis

An organism that is a gram-negative coccobacillus, grows on Bordet Gengou agar with mercury drop
colony appearance and biochemically inert is:

Bordetella pertussis

A positive cytochrome oxidase test is used to identify:

Neisseria species

Select the best response from the chart given:
Glucose - Maltose - Sucrose - Lactose -

Moraxella catarrhalis

Select the best response from the chart given:
Glucose + Maltose + Sucrose - Lactose -

Neisseria meningitidis

Both Neisseria meningitidis and Neisseria gonorrhoeae are positive for glucose, but only Neisseria
meningitis is positive for:

Maltose

The non-pathogenic Neisseria and Moraxella species have all of the following in common except:

Can cause opportunistic infections of the ear

Neisseria species may be identified by which of the following sugars?

Dextrose, sucrose, maltose, lactose

The Elek toxigenicity test detects the presence of:

Exotoxin C. diptheria

Establishing the pathogenicity of a microorganism isolated from a child's throat as Corynebacterium
diptheriae would depend on:

Determining the presence of toxin

The ELEK plate is the in-vitro toxigenicity test for:

Corynebacterium diptheriae

A direct smear from a nasopharyngeal swab stained with Loeffler's methylene blue stain showed various
club shaped rods with deep blue metachromatic granules. The likely identification is:

Corynebacterium spp.

Transmission of M. tb is by:

airborne droplet nuclei 1-5

Mycobacterium tuberculosis has:

- High lipid content in the cell wall

In a normal person, the natural host defenses may ward of M. tb in the lung forming:

Ghon complexes

The Ziehl-Neelson or Kinyouns stain is used for:

Acid fast bacilli

A 51-year-old male was admitted to the hospital for a cardiovascular accident. An aspirated sputum is
sent for acid fast studies after several sputa have been negative. The fluorochrome stain shows four
acid-fast bacilli, which give a good fluorescence, and is reported to the doctor in charge of TB control.
The doctor reports that it does not fit the clinical picture, as the skin test was negative and x-ray normal.
A second aspirated sputum was sent. Two fluorescent bacilli are observed. Control slides were used in
each situation. With these facts, the most likely conclusion is:

Possible infection with a Mycobacterium spp. other than tuberculosis

The causative organism of tuberculosis is:

Mycobacterium tuberculosis

The small gram-negative rod that causes whooping cough is:

Bordetella pertussis

Specimens must be processed immediately for the isolation of the pathogenic Neisseria species because
these organisms are:

Sensitive to temperature extremes and drying

Loeffler's and Cystein-tellurite media are used to isolate the organisms in suspected causes of:

Diptheria

The most characteristic morphological forms of C. diptheriae are found in smears from a 18-24 hours
culture on the following medium:

Loefflers medium

Multi-drug resistant tuberculosis results from:

- Incomplete therapy or non-compliance

The best time to collect a sputum specimen for AFB culture is:

Early morning after 8 hours of fasting

A medium designed for the isolation of Bordetella pertussis is:

Bordet-Gengou

Select the best response from the chart given:
Glucose + Maltose + Sucrose - Lactose +

Neisseria lactamica

Which of the following rapid sugars are fermented by the organism Neisseria meningitidis?

Dextrose, maltose

The disease Diptheria is caused by the organism's ability to produce:

Toxin

The toxicity of a strain of Corynebacterium diptheriae is demonstrated by:

Elek plate or PCR

A gram-positive club shaped bacillus occurring in Chinese letter arrangement is probably a member of
the genus:

Corynebacterium

The appearance of bright yellow-orange, fluorescent acid-fast bacilli against a dark background is observed after using which of the following stains for Mycobacteria:

Auramine stain

The large lipid content in the cell wall of mycobacterium species is responsible for their:

Acid fastness after staining

A change in colony color upon addition of oxidase reagent is used to identify:

Neisseria species

When a physician orders susceptibility testing on Neisseria meningitidis, what is the fastest method to provide information?

Beta- Lactamase (Cefinase)

A direct smear from a nasopharngeal swab stained with Loeffler's methylene blue stain showed various club shaped rods with deep blue metachromatic granules. The most likely identification is:

Corynebacterium spp

The differentiation between the Neisseria species is made by

carbohydrate fermentation or PCR

The Elek plate is the in vitro toxigenicity test for:

Corynebacterium diphtheriae

All species of Neisseria produce the following enzyme

cytochrome oxidase

Loeffler's and Cystine-tellurite media are used to isolate the organisms in suspected causes of

diphtheria

The enzyme that breaks penicillin into penicilloic acid is`

Beta lactamase

Staph aureus is generally resistant to Penicillin G by what mechanism?

Beta lactamase production

A positive Beta lactamase test indicates

resistance to penicillin

Staphylococcus aureus would most likely be resistant to:

Penicillin

A procedure, which directly determines beta-lactamase production by an microorganism, is based on the detection of

Color change resulting from the breaking of beta-lactam rin of a chromogenic cephalosporin

the test we use to identify candida albicans

germ tube positive

moraxella oxidase result

positive

Acceptable sputum smear

multiple PMNs seen on the smear

rejected sputum smear

if 10 or more squamous epithelial cells are seen per low power field on gram stain

what does beta lactamase tell us

-The enzyme that breaks penicillin into penicilloic acid
-Color change resulting from the breaking of beta-lactam rin of a chromogenic cephalosporin
-resistance to penicillin
-Staph aureus is generally resistant to Penicillin G
-When a physician orders susceptibility testing on Neisseria meningitides, the fastest method to provide information

H. influenzae

Chocolate agar with factors V (NAD+) and X (hematin)

H. parainfluenzae

Requires only V factor

Which of the following may be implicated in Neisseria gonorrhoeae infections:

All of the above (ophthalmia neonatorum, urethritis in males, joint and synovial fluid infection [arthritis], pelvic inflammatory disease [PID])

In females, the best site to culture for suspected gonorrhea is the:

Cervix

Select the best response from the chart given: glucose +, maltose -, sucrose -, lactose -

Neisseria gonorrhoeae

The alphabetical symbol used to denote the somatic antigen is the letter:

O

The genus of the family Enterobacteriaceae with which the "swarming" phenomenon is associated is:

Proteus

The medium, which is MOST inhibitory to gram-positive organisms and normal enteric flora, is:

Hektoen

Reactions on a TSI slant were: K/A with gas and H2S. These reactions could be produced by:

Salmonella

A positive urea slant would be typical of which of the following:

Klebsiella pneumoniae

All species of the genus Shigella are characteristically

Nonmotile

Which of the following tests may differentiate Proteus from Providencia and Morganella

H2S