American Society of Microbiology ASM-ABMM Online Practice Questions and Exam Preparation

American Society of Microbiology ASM-ABMM Online Questions & Answers

• Question 121:

  Acyclovir is a commonly used antiviral agent effective against Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV). Its selective toxicity relies on which initial step for activation within infected cells?

  A. Phosphorylation by host cell mitochondrial kinases
  B. Monophosphorylation primarily by viral thymidine kinase
  C. Direct inhibition of viral RNA polymerase activity
  D. Blocking viral entry through competitive inhibition of cellular receptors
  B. Monophosphorylation primarily by viral thymidine kinase

• Question 122:

  A microbiology laboratory is investigating a possible outbreak of Salmonella infection. Serological testing of patient isolates reveals they all possess the same O antigen but different H antigens. This suggests:

  A. A single point source of infection with a genetically stable strain.
  B. Multiple sources of infection with unrelated Salmonella strains.
  C. A common ancestral strain that has undergone flagellar antigen variation.
  D. Contamination in the laboratory affecting multiple samples.
  C. A common ancestral strain that has undergone flagellar antigen variation.

• Question 123:

  A microbiology laboratory is investigating an outbreak of bloodstream infections in a neonatal intensive care unit. Isolates of Staphylococcus epidermidis from multiple infants show indistinguishable banding patterns by pulsed-field gel electrophoresis (PFGE). This finding MOST strongly suggests:

  A. Widespread antibiotic resistance within the S. epidermidis population.
  B. A common source of infection and clonal spread of the organism.
  C. Recent horizontal gene transfer of virulence factors.
  D. Spontaneous mutations leading to increased pathogenicity.
  B. A common source of infection and clonal spread of the organism.

• Question 124:

  A patient with a history of travel to a developing country presents with chronic diarrhea, abdominal pain, and weight loss. Stool examination reveals the presence of cysts containing four nuclei and chromatoidal bars with rounded ends. The MOST likely causative organism is:

  A. Giardia lamblia
  B. Entamoeba histolytica
  C. Cryptosporidium parvum
  D. Cyclospora cayetanensis
  B. Entamoeba histolytica

• Question 125:

  The direct fluorescent antibody (DFA) test is commonly used for the rapid detection of which respiratory pathogen directly from nasopharyngeal specimens?

  A. Mycoplasma pneumoniae
  B. Legionella pneumophila (serogroup 1 in sputum)
  C. Influenza virus
  D. Bordetella pertussis
  D. Bordetella pertussis

• Question 126:

  A patient with cystic fibrosis experiences a pulmonary exacerbation. Sputum culture grows a mucoid strain of Pseudomonas aeruginosa. The mucoid phenotype is primarily due to the overproduction of:

  A. Exotoxin A
  B. Elastase
  C. Alginate
  D. Pyocyanin
  C. Alginate

• Question 127:

  A diagnostic laboratory is validating a new multiplex PCR panel for respiratory pathogens. According to CLIA regulations, which of the following parameters must be established by the laboratory performing the validation for this qualitative nucleic acid amplification test?

  A. Accuracy, Precision, Reportable Range, Analytical Sensitivity
  B. Accuracy, Precision, Clinical Sensitivity, Clinical Specificity
  C. Accuracy, Precision, Analytical Sensitivity, Analytical Specificity (including cross- reactivity)
  D. Precision, Reportable Range, Analytical Specificity, Reference Interval
  C. Accuracy, Precision, Analytical Sensitivity, Analytical Specificity (including cross- reactivity)

• Question 128:

  A clinical microbiology laboratory encounters a Gram-negative bacillus isolated from a bloodstream infection. The isolate exhibits resistance to multiple antibiotics, including carbapenems. Further phenotypic testing reveals the production of a metallo-beta- lactamase (MBL). Which of the following antibiotic combinations might still retain activity against this isolate?

  A. Ceftazidime-avibactam
  B. Piperacillin-tazobactam
  C. Aztreonam
  D. Aztreonam-avibactam
  C. Aztreonam

• Question 129:

  A clinical microbiology laboratory is implementing a new multiplex nucleic acid amplification test (NAAT) for the detection of respiratory viral pathogens. To ensure the quantitative accuracy of the assay, it is essential to include:

  A. Only positive and negative controls.
  B. External quality assessment samples.
  C. Calibration standards with known concentrations of target nucleic acids.
  D. Internal controls to monitor for PCR inhibition.
  C. Calibration standards with known concentrations of target nucleic acids.

• Question 130:

  Microscopic examination of a potassium hydroxide (KOH) preparation of skin scrapings from a patient with tinea versicolor typically reveals:

  A. Cigar-shaped yeast cells
  B. Septate hyphae and arthroconidia
  C. Broad, aseptate hyphae with sporangiophores
  D. Short, unbranched hyphae and globose yeast cells in clusters ("spaghetti and meatballs")
  D. Short, unbranched hyphae and globose yeast cells in clusters ("spaghetti and meatballs")