lab micro

The following characteristic of staphylococcal colony are, except: round. raised. opaque. 1-4 mm in diameter.

The string test is positive in : Salmonella spp. Shigella spp. Vibrio cholerae. Campylobacter jejuni.

What is the primary laboratory method for the diagnosis of Hepatitis A virus infection?. PCR detection of viral RNA. Liver biopsy. Serology. Viral culture.

The most accurate marker of HBV replication is: HbsAg. Anti-HBc IgG. HBV DNA detected by PCR. ALT level.

The actions of alchol-acetone during Gram staining are: all of the above. add color. allows decolorization. none of these.

A normal pap smear result indicates: Presence of HPV DNA. Cervical intraepithelial neoplasia. No cytologic abnormalities. Invasive cervical cancer.

An abnormal pap smear results indicates: Presence of HPV DNA. Cervical intraepithelial neoplasia. No cytologic abnormalities. Invasive cervical cancer.

The selective medium used for isolation of Vibrio Cholerae is: Mac Conkey agar. CIN agar. TCBS agar. EMB agar.

The selective medium used for isolation of Yersinia is: Mac Conkey agar. CIN agar. TCBS agar. EMB agar.

Which of the following bacteria will grow as pink colonies on MacConkey agar?. Salmonella enterica. Shigella dysenteriae. Escherichia coli. Pseudomonas aeruginosa.

Which organism produces colonies with a metallic green sheen on EMB agar?. Salmonella enterica. Shigella dysenteriae. Escherichia coli. Pseudomonas aeruginosa.

The MIC is defined as: Lowest bactericidal concentration. Highest antibiotic concentration. Lowest concentration inhibiting visible growth. Largest inhibition zone.

The role of Gram’s iodine in the Gram stain is to: Decolorize Gram-negative bacteria. Stain Gram-negative bacteria. Form the crystal violet–iodine complex.

HIV diagnosis is primarily based on: Viral culture. Detection of proviral DNA. Serological tests (anti-HIV antibodies and/or p24 antigen). Liver biopsy.

The Kirby–Bauer method is performed on: Blood agar. Chocolate agar. Mueller–Hinton agar. EMB agar.

The rapid urease test for Helicobacter pylori is based on: H₂S production. Lactose fermentation. Urea hydrolysis with pH change. Nitrate reduction.

The urea breath test for Helicobacter pylori is positive: After eradication therapy. In past infection. Only in active infection. Regardless of bacterial presence.

The main purpose of streaking an agar plate is to: Increase bacterial growth. Preserve bacterial viability. Isolate a pure bacterial strain from a mixed population. Determine antibiotic susceptibility.

Absence of Helicobacter pylori antigen in stool indicates: Reinfection. Chronic infection. Successful eradication after treatment. Transient colonization.

Modified Thayer–Martin medium is used to isolate: Haemophilus influenzae. Neisseria meningitidis. Neisseria gonorrhoeae. Moraxella catarrhalis.

Which structure retains dye in Gram-positive bacteria?. Outer membrane. Lipopolysaccharide. Thick peptidoglycan layer. Capsule.

Haemophilus influenzae requires which growth factors on chocolate agar?. Factor K and factor M. Factor X and factor Y. Factor X (hemin) and factor V (NAD). Iron and glucose.

Yersinia spp. show: Growth only at 37 °C. Growth at low temperatures (25–28 °C). Rapid lactose fermentation. Oxidase positivity.

The catalase test differentiates: Staphylococcus aureus from Escherichia coli. Staphylococcus aureus from Enterococcus. Staphylococci from streptococci. Streptococci from enterobacteria.

Which biochemical test is positive for Campylobacter jejuni?. Urease. Oxidase. Hippurate hydrolysis. Indole.

The most accurate marker of HBV replication is: HBsAg. Anti-HBc IgG. HBV DNA detected by PCR. ALT level.

What does a positive citrate test look like?. The media becomes blue due to alkaline byproducts. The media turns yellow due to acid production. The media turns green. The media remains unchanged.

Screening tests for HIV infection are characterized by: High specificity. Lower specificity. High sensitivity. Detection of viral genome.

The appropriate management for LSIL is: Immediate treatment. Colposcopy with biopsy. Observation only. Hysterectomy.

Which color does Vibrio cholerae produce on TCBS agar?. Green, due to lack of sucrose fermentation. Yellow, due to sucrose fermentation. Blue, due to alkaline byproducts. Colorless, due to glucose fermentation.

12. Which is the primary method for the diagnosis of HIV infection?. Viral culture. Detection of viral DNA by PCR. ELISA test for detection of anti-HIV antibodies (± p24 antigen). CD4⁺ T-cell count.

Cocci arranged in chains are characteristic of: Staphylococcus. Diplococci. Tetrads. Streptococcus.

After counterstaining, Gram-negative bacteria appear: Purple. Green. Pink to red. Blue.

Neisseria species are morphologically: Gram-negative bacilli. Gram-positive cocci. Gram-negative diplococci with coffee-bean appearance. Pleomorphic coccobacilli.

LSIL cytology is characterized by: Small nuclei and regular outlines. High nucleus-to-cytoplasm ratio. Perinuclear halos (koilocytosis). Absence of HPV effect.