Gram-Negative Bacteria — Neisseria, Haemophilus, Pseudomonas, Klebsiella MCQs

Microbiology · 7 free questions with answers & explanations.

1. A 6-year-old unimmunised child develops rapidly progressing meningitis. CSF Gram stain shows gram-negative coccobacilli. Blood and CSF cultures are inoculated on chocolate agar supplemented with X (hemin) and V (NAD) factors and satellite growth is observed near Staphylococcus streak. Which organism is responsible, and what is the capsular serotype associated with the highest virulence in children?
2. Pseudomonas aeruginosa is isolated from a burn wound with mucoid colonies. Which pigment produced by P. aeruginosa gives its characteristic blue-green discolouration, and what is the significance of mucoidy in clinical infections?
3. A 55-year-old alcoholic man develops pneumonia with 'currant-jelly' sputum, consolidation predominantly in the upper lobes and early cavitation on CXR. Blood and sputum cultures grow mucoid, string-test positive (mucoviscosity) lactose-fermenting gram-negative rods. What is the organism and its primary virulence mechanism in pulmonary infection?
4. A 19-year-old college student presents with sudden onset high fever, petechial rash rapidly evolving to purpura fulminans and shock. CSF shows gram-negative diplococci intracellularly in neutrophils. Which serogroup of Neisseria meningitidis is responsible for most meningococcal disease in India and which vaccine is recommended?
5. Neisseria gonorrhoeae is isolated from a urethral swab on Thayer-Martin medium. The antibiogram shows resistance to penicillin, azithromycin, and ciprofloxacin. According to current WHO/Indian treatment guidelines for multidrug-resistant gonococcal urethritis, the preferred treatment is:
6. Pseudomonas aeruginosa produces greenish-blue pigmentation in culture. The pigment responsible for the blue-green colour is:
7. A child presents with invasive Haemophilus influenzae type b (Hib) meningitis. H. influenzae requires which growth factors for culture on blood agar?