All are true regarding Campylobacter jejuni except?
A. It is the commonest cause of campylobacteriosis
B. Humans act as important reservoirs
C. It is associated with Guillian Barre syndrome
D. Poultry is a common source of infection
Correct answer :B. Humans act as important reservoirs

Humans do not act as reservoirs for Campylobacter jejuni
Important reservoirs are poultry, cattle, swine and household pets

All of the following statements regarding Corynebacterium diphtheriae are true, except?
A. It can be identified by using tests for toxigenicity
B. The toxin inhibits protein synthesis
C. Toxin has adverse effects on cardiovascular and nervous systems
D. Native chromosome is responsible for toxin production
Correct answer : D. Native chromosome is responsible for toxin production
Toxin production is mediated by toxigenic bacteriophages. The gene is transmitted via transduction.

False regarding Methicillin Resistant Staphylococcus aures (MRSA) ?
A. Resistance may be produced by increased production of beta lactamase enzyme
B. Resistance is primarily plasmid mediated
C. Resistance is due to altered Penicillin Binding Proteins
D. Resistance may be missed at incubation temperature of 37°C during susceptibility testing
Correct answer : B. Resistance is primarily plasmid mediated
Resistance is mediated by the MeC-A gene which codes for altered Penicillin Binding Proteins. MeC-A gene is part of nuclear chromosomes.

The letter ‘C’ in C Reactive Protein refers to?
A. Cellular
B. Concanavalin A
C. Calretinin
D. Capsular polysaccharide in Pneumococcus
Correct answer : D. Capsular polysaccharide in Pneumococcus

C Reactive Protein belongs to the pentraxin family of proteins which have the property of precipitating C substance polysaccharide of Streptococcus pneumoniae.
Pentraxins, also known as pentaxins, are an evolutionary conserved family of proteins characterised by containing a pentraxin protein domain.
Proteins of the pentraxin family are involved in acute immunological responses.

Which of the following organisms do not have polysaccharide capsule related antigen – antibody responses?
A. Streptococcus pneumoniae
B. Neisseria meningitidis
C. H. influenzae
D. Bordetella pertussis
Correct answer : D. Bordetella pertussis
Polysaccharide capsule related antigen – antibody responses are not significant in case of Bordetella pertussis. But for the other 3 organisms, it forms an important part of their pathogenicity.

An eight year old child presented to the pediatrics OPD with complaints of pain and discharge from left ear. Clinical examination revealed fever, neck rigidity and positive Kernig’s sign. Gram positive cocci were seen in the ear discharge on gram staining. Which is the most probably etiological agent?
A. Hemophilus influenzae
B. Streptococcus pneumoniae
C. Staphylococcus aureus
D. Pseudomonas aeruginosa
Correct answer : B. Streptococcus pneumoniae

The clinical features (otitis media with meningitis) and microbiological characteristics (gram positive cocci) are suggestive of infection with Streptococcus pneumoniae
Hemophilus influenzae and Pseudomonas aeruginosa are gram negative bacilli – hence …

False regarding Pneumococcus is?
A. Causes mild form of meningitis
B. Respiratory tract of carriers is the most important source of infection
C. Commonest cause of otitis media
D. Capsule is important in virulence
Correct answer : A. Causes mild form of meningitis
Pneumococcal meningitis is very severe and is fatal if untreated.

A patient presented to the OPD with clinical features of pneumonia. Sputum examination of the patient revealed a gram positive cocci with alpha hemolysis on sheep agar. Which test will you do to confirm the diagnosis?
A. Coagulase test
B. Bacitracin sensitivity
C. CAMP test
D. Bile solubility
Correct answer : D. Bile solubility

The clinical features and microbiological characteristics are suggestive of pneumococcal pneumonia
The diagnosis can be confirmed by Bile solubility and Optochin sensitivity

Which chemical is the most commonly used as a fixative for pathological specimens?
A. Picric acid
B. Mercuric chloride
C. Ethanol
D. Formaldehyde
Correct answer : D. Formaldehyde

Fixation is the process by which the morphological features of tissues are preserved
All of the above chemicals can be used a fixatives for pathological specimens
But formalin (solution of formaldehyde in water) is the most commonly used fixative
Formaldehyde is a colourless gas at room temperature with a pungent smell

Psammoma bodies are not seen in?
A. Meningioma
B. Papillary carcinoma thyroid
C. Follicular carcinoma thyroid
D. Serous cystadenocarcinoma of ovary
Correct answer: C. Follicular carcinoma thyroid
Psammoma bodies are characteristically seen in:

Papillary carcinoma thyroid
Meningioma
Serous cystadenocarcinoma of ovary
Renal cell carcinoma
Breast cancer, lung cancer, malignant mesotheliomas (occasional)