MLT GlobeQCHP exam preparation (Qatar) – page 17
749 practice MCQs for the QCHP medical laboratory exam. Level: Intermediate.
Stool from a patient with bacillary dysentery due to Shigella typically contains:
Shigella invades the colonic mucosa, giving small-volume stools with blood, mucus and neutrophils.
Chlamydia trachomatis cannot be grown on ordinary agar media because it:
Chlamydiae depend on host-cell energy, so they are grown only in cell culture or detected by NAAT.
On a Gram stain, Neisseria species typically appear as:
Neisseria are Gram-negative cocci in pairs with their flat sides facing, giving a kidney-bean shape.
Neisseria gonorrhoeae attaches to mucosal epithelial cells mainly by means of:
Gonococcal pili mediate adherence to urethral and cervical cells; Neisseria have no flagella and form no spores.
Which anaerobe is most frequently isolated from intra-abdominal abscesses and other anaerobic infections?
B. fragilis is the most commonly isolated anaerobic pathogen, especially after bowel perforation.
Patients taking rifampicin for tuberculosis should be told that the drug commonly:
Rifampicin is a red-orange pigment that colours urine, sweat and tears; this is harmless.
Which of these is a first-line anti-tuberculosis drug?
Standard first-line TB treatment uses isoniazid, rifampicin, pyrazinamide and ethambutol.
Multidrug-resistant tuberculosis (MDR-TB) is defined as resistance to at least:
MDR-TB means resistance to at least isoniazid and rifampicin, the two most important first-line drugs.
A Mantoux tuberculin skin test is read how long after injection?
The test measures delayed-type hypersensitivity, so the induration is read after 48–72 hours.
Humans become infected with Entamoeba histolytica by swallowing which stage?
The mature quadrinucleate cyst survives stomach acid and excysts in the intestine; trophozoites are destroyed outside the body and by gastric acid.
Why must spillage of hydatid cyst fluid be avoided during aspiration or surgery?
Cyst fluid is highly antigenic and contains protoscolices, so leakage can cause anaphylactic shock and secondary cysts.
The segments that make up the body of a tapeworm are called:
The strobila is a chain of proglottids; the scolex is the attachment organ at the head end.
Fungal hyphae with regular cross-walls are described as:
Septate hyphae have cross-walls (septa), as in Aspergillus and dermatophytes; Mucorales have mostly aseptate hyphae.
Routine fungal cultures for moulds are usually incubated at:
Most moulds grow best at 25–30 °C; 37 °C is used additionally to show the yeast phase of dimorphic fungi.
Yeasts such as Candida reproduce asexually mainly by:
Yeasts form buds (blastoconidia) that pinch off from the parent cell.
Candida albicans is best described as:
C. albicans is normal flora of the mouth, gut and vagina and causes disease when defences or normal flora are disturbed.
Against which of these viruses is there currently no licensed vaccine in routine use?
Hepatitis C is prevented by blood safety measures and treated with antivirals, but no vaccine exists; hepatitis A, hepatitis B and measles vaccines are routinely used.
SARS-CoV-2, the cause of COVID-19, belongs to which virus family?
SARS-CoV-2 is an enveloped positive-sense RNA betacoronavirus of the family Coronaviridae.
Chikungunya fever is characterised especially by:
The name comes from a Makonde word for 'that which bends up', reflecting the disabling arthralgia.
Which statement about antibody structure is FALSE?
Class (isotype) depends on the heavy chain; kappa or lambda light chains occur in every class. IgG has two identical binding sites.