ASCP 2023 exam Flashcards
Which one of the following anaerobes is inhibited by sodium polyanethol sulfonate (SPS)?
Peptostreptococcus anaerobius
A common cause of acute exudative pharyngitis is:
Streptococcus pyogenes
Polyvinyl alcohol used in the preparation of permanently stained smears of fecal material:
serves as an adhesive
The characteristic that is most commonly associated with the presence of strict anaerobic bacteria and can be taken as presumptive evidence of their presence in a clinical specimen is the
presence of a foul, putrid odor from tissue specimens and cultures
What stain is most often used as a screening stain when mycobacteria is suspected in a respiratory specimen?
auramine O
Which organism is the most common anaerobic bacteria isolated from infectious processes of soft tissue and anaerobic bacteremia?
B. fragilis
The primary isolation of Neisseria gonorrhoeae requires:
CO2
Shigella species characteristically are
nonmotile
In reviewing the number of Mycobacterium isolates for the current year, it is noted that there were 76% fewer isolates than the previous year (115 vs 28). The technologist in charge of the area has documented that the quality control of media, reagents and stains has been acceptable and there has been no gross contamination of the cultures noted. The most appropriate next course of action is to:
review the digestion and decontamination procedure
Which organism is predominantly responsible for visceral larva migrans?
Toxocara canis
which one of the following organisms could be used as the positive quality control test for lecithinase on egg yolk agar?
Clostridium perfringens
Organisms that are part of the Mycobacterium tuberculosis complex (MTBC) include Mycobacterium tuberculosis and:
M. africanum and M. bovis
A positive niacin test is characteristic of Mycobacterium:
tuberculosis
Small protozoan cysts are found in a wet mount of sediment from ethyl-acetate concentrated material. Each cyst has 4 nuclei that do not have peripheral chromatin, and each nucleus has a large karyosome, which appears as a refractive dot. These oval cysts are most likely
Endolimax nana
Which DNase-positive organism’s colony is not easily broken up and therefore displays the “hockey puck” characteristic, where it can be pushed across the plate of medium?
Moraxella catarrhalis
A reliable test for distinguishing Staphylococcus aureus from other staphylococci is:
coagulase
Which type of virus causes severe acute respiratory syndrome?
coronavirus
A young girl cuts her foot on a rock while swimming in the ocean. Her foot begins to show signs of infection, and her parents take her to the ER. A culture grows non-lactose fermenting gram-negative bacilli that produce copious amounts of hydrogen sulfide and gas, is indole-positive and motile. The organism most likely isolated is:
Edwardsiella species
Which one of the following clinical syndromes is associated with VZV infection?
shingles
Anaerobic, box-car shaped, beta-hemolytic gram-positive bacilli isolated from a foot wound are most likely:
Clostridium perfringens
A method to culture Acanthamoeba species from corneal ulcer scrapings is to inoculate:
an agar plate overlaid with Escherichia coli
An isolate on chocolate agar from a patient with epiglottitis is suggestive of Haemophilus species. Additional testing shows that the isolate required NAD for growth and is nonhemolytic. The organism is most likely Haemophilus:
parainfluenzae
What precaution should be taken to prevent infection of laboratory personnel when processing specimens for mycobacterial culture?
process all specimens in a biological safety hood
Group B, beta-hemolytic streptococci may be distinguished from other hemolytic streptococci by which of the following procedures?
latex antigen grouping
Which one of the following media is most helpful in distinguishing the morphology of yeasts?
cornmeal agar with Tween 80
The recommended medium/media to inoculate for the primary isolation of Mycobacteria include:
a broth-based and a solid-based medium
In a person vaccinated against hepatitis B virus several years prior, which serological marker would be expected?
anti-HBs
Relapsing fever in humans is caused by
Borrelia recurrentis
Gram stain of a thigh wound shows many gram-positive spore-forming bacilli. The specimen is placed on brain-heart infusion blood agar and incubated aerobically at 35°C for 3 days. At the end of that time, the plates show no growth. The most likely explanation is that some of the specimen should have been incubated
anaerobically
Darkfield microscopy is used to visualize
Treponema pallidum
Small, pleomorphic gram-negative bacilli are isolated from an eye culture. They grow only on chocolate agar and are oxidase-variable. The most likely organism is:
Haemophilus influenzae
Differentiation of Mycobacterium avium from Mycobacterium intracellulare can be accomplished by
molecular testing
The Gram stain of drainage from a pulmonary sinus tract shows many WBCs and 3+ branching gram-positive bacilli. Colonies grow only on anaerobic media after 3 days’ incubation. They are yellow-tan and have a molar tooth appearance. The most likely genus is:
Actinomyces
The principal difference between the Ziehl-Neelsen acid-fast stain technique and the Kinyoun acid-fast stain technique is the:
use of heat to allow the dye to penetrate organism
Fluid from a cutaneous black lesion is submitted for routine bacterial culture. After 18 hours of incubation at 35°C there is no growth on MacConkey agar, but 3+ growth on sheep blood agar. The colonies are nonhemolytic, nonmotile, 4 - 5 mm in diameter and off-white with a ground glass appearance. Each colony has an irregular edge with comma-shaped outgrowths that stand up like “beaten egg whites” when gently lifted with an inoculating needle. A Gram stain of a typical colony shows large, gram-positive rectangular bacilli. The organism is most likely:
Bacillus anthracis
A catheterized urine is inoculated onto blood and MacConkey agar using a 0.01 mL loop. After 24 hours, 68 colonies of a small translucent nonhemolytic organism grew on blood agar, but not MacConkey. Testing reveals small gram-positive, catalase-negative cocci. The preliminary report and follow up testing would be:
growth of 6800 CFU/mL of a Streptococcus species, esculin hydrolysis and 6.5% NaCl growth test to follow
A patient has a suspected diagnosis of subacute bacterial endocarditis. His blood cultures grow non-spore-forming pleomorphic gram-positive bacilli only in the anaerobic bottle. What test(s) will give a presumptive identification of this microorganism?
catalase and spot indole
An organism previously thought to be nonpathogenic, Moraxella catarrhalis, is now known to be associated with opportunistic respiratory infection and nosocomial transmission. Characteristic identification criteria include:
butyrate esterase-positive
A fibrous skin nodule is removed from the back of a patient from Central America. A microfilaria seen upon microscopic exam of the nodule is most likely:
Onchocerca volvulus
Primary amoebic encephalitis is caused by:
Naegleria fowleri
An Enterococcus isolated from multiple blood cultures in a patient endocarditis should be:
screened for high-level aminoglycoside resistance
A blood culture bottle with macroscopic signs of growth is Gram stained and the technician notes small, curved gram-negative bacilli resembling “gull wings.” It is subcultured to blood and chocolate agar, and incubated aerobically and anaerobically. After 24 hours, no growth is apparent. The next step should be to:
subculture the bottle, and incubate in microaerophilic conditions
Differentiating tests that will separate Burkholderia from Stenotrophomonas include:
oxidase
Tests for Haemophilus influenzae beta-lactamase production:
should be performed on all blood and CSF isolates
The most frequent cause of prosthetic heart valve infections occurring within 2 - 3 months after surgery is:
Staphylococcus epidermidis
The laboratory aid prepared and performed a Gram stain of a vaginal smear for Neisseria gonorrhoeae, as requested by a resident. The findings on the stain were:
many white blood cells
few epithelial cells
many gram-positive bacilli
few gram-negative diplococci
few gram-positive cocci in chains
The technologist should:
not read or report a Gram stain on a vaginal specimen
Which medium could a technologist use to verify that a yeast isolate from a blood culture is pure?
CHRomagar
Gamma-hemolytic streptococci that blacken bile esculin agar but do not grow in 6.5% NaCl broth are most likely:
group D Streptococcus (Streptococcus bovis group)
Which one of the following viruses is responsible for the most common congenital infection in the United States?
CMV
Examples of Category A agents of bioterrorism include:
Francisella tularensis, Yersinia pestis
Where do Plasmodium sporozoites proliferate?
liver
Which of the following is the most reliable test to differentiate Neisseria lactamica from Neisseria meningitidis?
rapid ONPG
Gram-positive cocci in chains are seen on a Gram stain from a blood culture. The organism grows as a beta-hemolytic colony. Further tests that could be performed include:
PYR, bacitracin, and hippurate
This organism is responsible for hydatid cysts of the liver:
Echinococcus
An organism that may be mistaken for Neisseria gonorrhoeae in Gram-stained smears of uterine cervix exudates is:
Moraxella osloensis
A pregnant patient is screened at 36 weeks’ gestation for group B Streptococcus (GBS). A vaginal swab is collected and cultured in Todd-Hewitt broth with 8 µg/mL gentamicin and 15 µg/mL nalidixic acid. The broth is subcultured onto sheep blood agar after 24 hours of incubation. No GBS are seen on the subculture and the results are reported as negative. The patient later goes on to deliver an infant with early onset GBS disease. What is the most likely reason for the negative GBS culture?
a vaginal swab was collected instead of a vaginal/rectal swab
This parasite is transmitted by accidental ingestion of cat feces that contain oocysts and by ingestion of undercooked meat that has tissue cysts. The parasite is:
Toxoplasma gondii
Microbiology-related urgent or critical results include positive:
blood cultures, cerebrospinal fluid cultures and acid-fast smears
A method for the definitive identification of Neisseria gonorrhoeae is
utilization of carbohydrates
The Epstein-Barr virus is associated with which of the following?
Burkitt lymphoma
Infection of the urinary tract is mostfrequently associated with:
E. coli
Representative beta-lactam antibiotics and their mechanism of action includ
ampicillin, cefazolin and imipenem; and inhibition of cell wall synthesis
During the previous month, Staphylococcus epidermidis has been isolated from blood cultures at 2 - 3 times the rate from the previous year. The most logical explanation for the increase in these isolates is that
there has been a break in proper skin preparation before drawing blood for culture
A 3-year-old unimmunized female presents to the ER with a severe cough, fever, and flu-like symptoms. The parents report that the child had vomited a few times due to the severe coughing. A nasopharyngeal swab is used to collect the specimen and planted on a chocolate, Bordet-Gengou, and Regan Lowe media. After 5 days of incubation, colonies grow on all of the media, with the growth on Bordet-Gengou described as “drops of mercury.” The Gram stain shows minute coccobacilli that are catalase-positive and oxidase-positive. The most likely identification of this isolate is:
Bordetella pertussis
The laboratory is considering adoption of a rapid and sensitive “stand alone” method that detects Clostridioides difficile toxins A and B. Which one of the following testing methodologies will provide this?
NAAT
A very bloody stool is received by the laboratory. The following day a pathogenic strain of E. coli is isolated. Which sugar should this isolate be tested against to begin the identification process?
sorbitol
A technologist on the respiratory bench notices an increased number of patients on the ICU growing the same, drug-resistant gram-negative bacilli from sputum specimens. Which department in the hospital will the microbiology laboratory work with to collect data on positive patients?
Infection control
The organism most commonly associated with neonatal purulent meningitis is:
group B streptococci
Microorganisms resembling Mycoplasma pneumoniae have been isolated from the blood of patients treated with antibiotics that:
interfere with cell wall synthesis
The stock cultures needed for quality control testing of deamination activity are:
Proteus mirabilis—Escherichia coli
When staining mycobacteria, the primary stain used in the acid-fast staining process is:
carbol fuchsin
Characteristics of the HACEK group of bacteria include:
requirement of 5 - 10% CO2 for growth
What organism combination is appropriate to serve as quality control for the listed test or organism characteristic?
indole: Escherichia coli and Proteus mirabilis
The optochin disk is used for the identification of:
Streptococcus pneumoniae
Which of the following gram-positive bacilli is associated with infections in neonates, pregnant women, elderly adults, and outbreaks of food contamination? I
Listeria monocytogenes
The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are:
Serratia marcescens—Escherichia coli
When compared to direct specimen carbol fuchsin stains used for detecting mycobacteria, fluorochrome stains are less sensitive for detecting mycobacteria classified as:
rapid growers
The genus of virus associated with anogenital warts, cervical dysplasia and neoplasia is
human papillomavirus
A characteristic that is helpful in separating Pseudomonas aeruginosa from other members of the Pseudomonas family is:
growth at 42°C
A liquid fecal specimen from a 3-month-old infant is submitted for culture. The stool culture should detect Salmonella, Shigella and:
Campylobacter species
Which nonculture method is best for the diagnosis of Neisseria gonorrhoeae in an adult female?
NAAT
Talaromyces (formerly Penicillium) species can be separated from Aspergillus fumigatus by:
lack of vesicle
Which of the following would best differentiate Streptococcus agalactiae from Streptococcus pyogenes?
hydrolysis of sodium hippurate
A 44-year-old man is admitted to the hospital following a 2-week history of low-grade fever, malaise and anorexia. Examination of a Giemsa stain reveals many intraerythrocytic parasites. Further history reveals frequent camping trips near Martha’s Vineyard and Nantucket Island, but no travel outside the continental United States. This parasite could easily be confused with:
Plasmodium falciparum
An organism has been identified as a member of the fluorescent group of Pseudomonas. Which of the following sets of tests should be used to determine the species of the organism?
growth at 42°C, pyocyanin production, gelatinase production
An Enterobacterales organism will appear to be more resistant on a disk diffusion susceptibility test if the:
inoculum is too concentrated
A branching gram-positive, partially acid-fast organism is isolated from a bronchial washing on a 63-year-old woman receiving chemotherapy. The organism does not hydrolyze casein, tyrosine or xanthine. The most likely genus causing the infection is:
Nocardia
While swimming in a lake near his home, a young boy cut his foot, and an infection developed. The culture grew a nonfastidious gram-negative, oxidase-positive, beta-hemolytic, motile bacilli that produced deoxyribonuclease (DNase). The mostlikely identification is:
Aeromonas hydrophila
Haemophilus influenzae becomes resistant to ampicillin when the organism produces:
the beta-lactamase enzyme
Cerebrospinal fluid test results that are most consistent with viral meningitis include:
lymphocytes predominant
The most sensitive substrate for the detection of beta-lactamases is:
nitrocefin
Penicillin resistance in Neisseria gonorrhoeae can be due to the organism producing:
beta-lactamase
What Mycobacterium species includes a BCG strain used for vaccination against tuberculosis?
bovis
Chlamydia trachomatis infections have been implicated in:
LGV and conjunctivitis
Infection by this organism can cause of B12 deficiency:
Diphyllobothrium latum
Which one of the following anaerobes is inhibited by sodium polyanethol sulfonate (SPS)?
Peptostreptococcus anaerobius
A common cause of acute exudative pharyngitis is:
Streptococcus pyogenes
The best medium for culture of Bordetella pertussis is:
Regan-Lowe agar
Polyvinyl alcohol used in the preparation of permanently stained smears of fecal material:
serves as an adhesive
The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are:
Serratia marcescens—Escherichia coli
