Microbiology Lab CE Post-Analytic Procedures

Which of the following is a characteristic of Francisella tularensis?

Tiny, weak-staining, gram-negative coccobacilli

Which of the following anthrax infections is also known as "woolsorter's disease"?

Inhalation anthrax

Which spirochete is a causative agent of human disease and is acquired through contact with the urine of carrier animals?

Leptospira interrogans sensu stricto

Which organ is the primary target of the hepatitis B virus?

Liver

Which of the following Mycobacterium species is closely associated with infections in HIV positive patients?

M. avium-intracellulare complex

The cellular immune response plays a role in whether a person exposed to Mycobacterium tuberculosis will develop tuberculosis disease (TB). Which of the following factors will make a person most at-risk of progressing from infection to active disease if exposed to M. tuberculosis?

Malnutrition

MIC is an acronym for:

Minimum inhibitory concentration

The following is the MOST likely identity of an acid-fast bacilli that showed buff colored, dry, heaped colonies; niacin, nitrate, and urease positive; and took 23 days at 35ºC to grow:

Mycobacterium tuberculosis

Which organism is a cell wall deficient bacterium that commonly causes primary atypical or "walking pneumonia?"

Mycoplasma pneumoniae

Which of the following tests would be most useful in the identification of Streptococcus pneumoniae?

Optochin

Oxacillin resistance of MRSA is due to production of which of the following penicillin binding proteins (PBPs)?

PBP2a

Which of the following would ensure positive patient identification prior to specimen collection?

Patient's full name and hospital or medical record number.

Which of the following biochemical reactions is most useful in establishing a definitive identification of Staphylococcus aureus?

Positive tube coagulase test

A blood culture yielded an organism with the following reactions: TSIA: K/A, gas (+), H2S (+) Citrate: Positive Indole: Negative Lysine: Positive Ornithine: Positive Motility: Positive Phenylalanine: Negative ONPG: Negative Urease: Negative What is the most likely identification of this organism?

Salmonella

Which of the following is used to standardize the bacterial inoculum used in a disk diffusion test (Kirby-Bauer method)?

0.5 McFarland standard

Which of the following is used to determine if a person has had a recent infection with Strep pyogenes?

Antistreptolysin O (ASO)

Bordet-Gengou plates are used to isolate:

Bordetella pertussis

The laboratory receives a synovial fluid for acid-fast culture. How should the tech proceed with this culture?

Centrifuge the specimen and directly inoculate the culture

Acute obstructive epiglottitis, both in adults and children, is most commonly caused by a specific bacterial species that can be recovered on chocolate agar and requires both hematin and NAD. The most likely identification is:

Haemophilus influenzae

Infections with Eikenella corrodens is associated with:

Trauma associated with human teeth

Which of the following has been compared to a hockey puck when discussing its morphology on chocolate agar?

moraxella

What color would the agar be around a colony of Staphylococcus epidermidis growing on mannitol salt agar (MSA)?

red

Which of the following describes a sentinel laboratory as part of the Laboratory Response Network (LRN)?

A laboratory that performs basic testing to rule out possible bioterrorism agents, and then refers any suspicious agents or specimens to an LRN reference laboratory

The upper photomicrograph illustrates a Gram stain of sputum obtained from a 55-year-old man with symptoms of bacterial pneumonia. The lower photograph represents the growth of an inoculum from the specimen on 5% sheep blood agar, on which had been placed an optochin ("P") and a 1 µg oxacillin disk. After 18 hours incubation at 37°C in 5% CO2, the zone around the optochin disk is 18 mm and around the OX disk is 8 mm. The interpretation is that the organism is most likely:

A pneumococcus, penicillin resistant

Pseudomonas aeruginosa is often used as a bacterial species for the quality control of Kligler Iron Agar (KIA). The expected reaction is:

Alkaline slant/alkaline deep

All of the following statements are associated with MALDI-TOF mass spectrophotometry used in clinical microbiology, EXCEPT?

Bacteria is amplified using a laser.

Which of the following organisms produces a double zone of hemolysis on blood agar?

Clostridium perfringens

The following Clostridium difficile virulence factor is significant in the cause of antibiotic-associated pseudomembranous colitis:

Cytotoxin A or B

In order to speciate a swarming Proteus organism found on an eosin methylene blue (EMB) agar plate, the best approach would be to:

Determine indole production and ornithine decarboxylase

A positive RPR test and a negative FTA-ABS test is most likely the result of:

False positive reaction

Which organisms are the appropriate stock cultures for quality control testing of oxidase production?

Escherichia coli / Pseudomonas aeruginosa

A culture was performed on a stool sample. After growth was obtained on the blood agar plate, the gram stain showed curved gram negative rods. The oxidase, catalase, and urease were positive. What is the most likely bacterial identification?

Helicobacter pylori

Exudate from a burn submitted on a swab for bacterial culture grew a gram-negative bacillus that was oxidase-positive, produced an alkaline slant and butt on TSIA, was resistant to numerous antibiotics, and produced a green, water-soluble pigment. This organism would be identified as:

Pseudomonas aeruginosa

Rocky Mountain spotted fever (RMSF) is transmitted by the bite of a tick infected with:

Rickettsia rickettsii

Which of the following is a key benefit that molecular methods can offer over culture methods?

Reduced turnaround time

When an unpreserved urine specimen cannot be cultured immediately, which storage method is most appropriate?

Stored in the refrigerator at 4° C for up to 24 hours

The optochin (ethylhydrocupreine hydrochloride) disk is most often used for the identification of which organism?

Streptococcus pneumoniae

The federal government has categorized critical biological agents into three groups: A, B, and C. Why are the agents in category A classified as the highest-priority?

These organisms can be easily disseminated or transmitted person-to-person.

A 27-year-old man who had recently worked as a medical laboratory scientist on the Navajo Native American reservation presented to the emergency department with high fever, diarrhea, and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A smear was prepared from a lymph node aspirate and many Gram negative bacilli were noted. The bacilli demonstrated a marked bipolar staining reaction described as a "safety-pin appearance" with Wayson stain. What is the most likely identification of this organism?

Yersinia pestis

Which of the following is most commonly used as a routine staining technique in the clinical microbiology laboratory?

gram