A centrifuge rotor containing capped tubes of sputum concentrate for AFB culture breaks during operation inside a Class II Biological Safety Cabinet (BSC). What is the most appropriate immediate action for the technologist?
A clinical microbiology laboratory is monitoring the emergence of antimicrobial resistance. The detection of a bacterial isolate with reduced susceptibility to multiple classes of antibiotics, often due to horizontal gene transfer of resistance determinants, is characteristic of:
A patient with a history of travel to a tropical region presents with cyclical fevers and chills.Peripheral blood smear reveals the presence of merozoites and schizonts within erythrocytes. The absence of crescent-shaped gametocytes makes Plasmodium falciparum less likely. The MOST probable species is:
A Gram stain of cerebrospinal fluid (CSF) from a 2-year-old child with meningitis shows small, pleomorphic Gram-negative coccobacilli. Culture on chocolate agar yields growth, but there is no growth on standard 5% sheep blood agar unless streaked near a colony of Staphylococcus aureus. This phenomenon indicates a requirement for which growth factor(s)?
The direct fluorescent antibody (DFA) test is commonly used for the rapid detection of which respiratory pathogen directly from nasopharyngeal specimens?
A laboratory worker sustains a needlestick injury while handling a blood sample known to be positive for Hepatitis B surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg). The worker has completed the HBV vaccination series and has a documented anti-HBs titer >10 mIU/mL one month ago. What is the recommended post-exposure prophylaxis?
A clinical microbiology laboratory is using isothermal nucleic acid amplification techniques for rapid detection of Mycobacterium tuberculosis in sputum. Compared to conventional PCR, isothermal methods offer the advantage of:
A patient with HIV infection and a very low CD4+ T-cell count develops a disseminated infection with a fungus that is commonly found in pigeon droppings. The MOST likely causative agent is:
A patient with HIV infection and a CD4+ T-cell count below 100 cells/µL presents with headache, fever, and altered mental status. CSF analysis reveals elevated protein and low glucose. India ink stain is negative. Cryptococcal antigen test of the CSF is positive. The MOST appropriate initial treatment is:
Microscopic examination of a trichrome-stained stool smear reveals amoebic trophozoites approximately 25 µm in diameter, containing ingested red blood cells. The nucleus, when visible, has fine, evenly distributed peripheral chromatin and a small, central karyosome. These features are diagnostic for:
