Bacterial Zoonoses — MCQs
A 40-year old woman presented to the surgical OPD with features suggestive of colitis. She was on prolonged treatment with clindamycin. Fecal sample was positive for toxin produced by this agent. Her condition improved on treatment with metronidazole. The clinical condition is associated with -
Young female with 3 days fever presents with headache, BP 90/60 mmHg, Heart rate of 114/min, and pin point spots developed distal to BP cuff. Most likely organism is:
A clinically depressed farmer complains of extreme weakness, a daily rise and fall in fever, and night sweats. Small gram-negative rods are isolated from blood cultures after a 2-week incubation period. Which of the following organisms is the most likely etiologic agent?
A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
Which of the following is not a vector-borne disease?
Atrophic dry nasal mucosa, extensive encrustations, and a woody hard external nose are suggestive of which of the following conditions?
Animal to man transmission (zoonosis) is seen in -
A sewerage worker presents to OPD with acute febrile illness alongwith jaundice and conjunctivitis. His blood sample was taken and sent to lab . Lab findings are suggestive of kidney failure and elevated hepatic enzymes. Which of following is likely diagnosis ?
A patient presents with fever and jaundice after repairing sewers. What is the most appropriate test to diagnose the infection in this patient?
A girl from Shimla presented to OPD with fever, hypotension, malaise and axillary and inguinal lymphadenopathy. Culture in glucose broth shows stalactite growth. Most likely causative organism is?
Bacterial Zoonoses Indian Medical PG Practice Questions and MCQs
Question 1: A 40-year old woman presented to the surgical OPD with features suggestive of colitis. She was on prolonged treatment with clindamycin. Fecal sample was positive for toxin produced by this agent. Her condition improved on treatment with metronidazole. The clinical condition is associated with -
- A. Listeria monocytogenes
- B. Bacillus anthracis
- C. Clostridium difficile (Correct Answer)
- D. Acinetobacter baumannii
Explanation: ***Clostridium difficile*** - The history of **clindamycin use**, followed by **colitis symptoms**, a **positive fecal toxin test**, and improvement with **metronidazole**, are classic indicators of *Clostridium difficile* infection (CDI) [1]. - *C. difficile* produces toxins (Toxin A and Toxin B) that cause **pseudomembranous colitis**, often after antibiotic disruption of normal gut flora [1]. *Listeria monocytogenes* - This bacterium is primarily a cause of **foodborne illness**, leading to febrile gastroenteritis, meningitis, or sepsis, particularly in immunocompromised individuals, pregnant women, and neonates. - It is not typically associated with **antibiotic-associated colitis** or treated with metronidazole as a primary agent for bowel infection. *Bacillus anthracis* - This is the causative agent of **anthrax**, which can manifest as cutaneous, inhalational, or gastrointestinal forms. - **Gastrointestinal anthrax** causes severe abdominal pain, vomiting, bloody diarrhea, and fever, but it is rare and not linked to antibiotic use or toxin detection in stool in the context described. *Acinetobacter baumannii* - *Acinetobacter baumannii* is an important **opportunistic pathogen** often associated with hospital-acquired infections, such as pneumonia, urinary tract infections, and bloodstream infections, particularly in critically ill patients. - It is not a known cause of **antibiotic-associated colitis** due to toxin production, nor is metronidazole the primary treatment.
Question 2: Young female with 3 days fever presents with headache, BP 90/60 mmHg, Heart rate of 114/min, and pin point spots developed distal to BP cuff. Most likely organism is:
- A. Brucella suis
- B. N. meningitidis (Correct Answer)
- C. Staphylococcus aureus
- D. Brucella abortus
Explanation: ***N. meningitidis*** - The presentation of **fever**, **headache** [1], signs of **shock** (hypotension, tachycardia), and **petechiae/purpura** (pinpoint spots distal to BP cuff, indicating a bleeding disorder such as thrombocytopenia or DIC often associated with meningococcemia) is classic for **meningococcal sepsis**. - *Neisseria meningitidis* is well-known for causing **rapidly progressive sepsis with disseminated intravascular coagulation (DIC)** and a characteristic **petechial or purpuric rash**. *Brucella suis* - *Brucella suis* causes **brucellosis**, which typically presents with **undulating fever**, **arthralgia**, fatigue, and hepatosplenomegaly. - While it can cause systemic illness, it does not typically manifest with the acute, severe presentation of **sepsis** and **hemorrhagic rash** seen in this patient. *Staphylococcus aureus* - *Staphylococcus aureus* can cause widespread infections, including sepsis characterized by **fever**, **hypotension**, and **tachycardia**, often leading to **toxic shock syndrome**. [2] - However, while *S. aureus* can cause skin manifestations like cellulitis or abscesses, it is less commonly associated with the specific **petechial rash** in the context of acute sepsis, unless it's an endocarditis with septic emboli, which would have a different clinical scenario. [2] *Brucella abortus* - Similar to *Brucella suis*, *Brucella abortus* causes **brucellosis**, a chronic zoonotic infection. - The clinical picture of **acute fulminant sepsis with hemorrhagic skin lesions** is not characteristic of *Brucella abortus* infection.
Question 3: A clinically depressed farmer complains of extreme weakness, a daily rise and fall in fever, and night sweats. Small gram-negative rods are isolated from blood cultures after a 2-week incubation period. Which of the following organisms is the most likely etiologic agent?
- A. Campylobacter jejuni
- B. Francisella tularensis
- C. Brucella melitensis (Correct Answer)
- D. Salmonella enteritidis
Explanation: ***Brucella melitensis*** - This organism is known to cause **brucellosis**, which presents with **undulant fever** (daily rise and fall), night sweats, and fatigue, consistent with the patient's symptoms. The profession of a **farmer** puts him at higher risk due to exposure to infected livestock. - **Neuropsychiatric manifestations** including depression, fatigue, and malaise are well-recognized features of chronic brucellosis, explaining the patient's clinical depression. - **_Brucella_ species** are characteristic for their slow growth, often requiring **extended incubation periods** (up to 2 weeks) in blood cultures, and appear as small gram-negative rods. *Campylobacter jejuni* - This bacterium is a common cause of **gastroenteritis**, leading to **diarrhea**, abdominal cramps, and fever. While it can cause bacteremia, it typically presents with more prominent gastrointestinal symptoms. - _C. jejuni_ is a **curved or spiral-shaped** gram-negative rod, distinct from the small rods described, and does not typically cause an undulant fever pattern. *Francisella tularensis* - This agent causes **tularemia**, which can manifest with fever, chills, and fatigue, but often includes a characteristic **skin lesion (ulceroglandular)** and prominent lymphadenopathy. - Although it is a small gram-negative rod, the specific **undulant fever pattern** and the farmer's exposure history are more indicative of brucellosis. *Salmonella enteritidis* - This bacterium commonly causes **food poisoning** with symptoms like diarrhea, fever, and vomiting. While it can lead to bacteremia, it is less likely to present with the prolonged, **undulant fever** seen in brucellosis. - **_Salmonella_ species** are typically readily isolated from blood cultures within a few days, unlike the prolonged incubation needed for _Brucella_.
Question 4: A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
- A. Brucella suis
- B. Neisseria meningitidis (Correct Answer)
- C. Brucella abortus
- D. Staphylococcus aureus
Explanation: Neisseria meningitidis - The combination of sore throat, fever, headache, severe dehydration, hypotension, and petechiae (small red spots from broken capillaries, often seen with bleeding diathesis) is highly suggestive of meningococcemia [1]. - Neisseria meningitidis can cause fulminant sepsis and meningitis, leading to rapid progression of symptoms including DIC and widespread petechial rashes due to vasculitis [2]. Brucella suis - Brucellosis typically presents as an insidious illness with undulating fever, arthralgia, and organomegaly, not sudden onset severe symptoms with dehydration and petechiae. - While it can be severe, it does not commonly manifest with the acute, dramatic hemorrhagic signs seen in this patient. Brucella abortus - Similar to Brucella suis, Brucella abortus causes brucellosis, which is a chronic or subacute infection. - The clinical picture of acute onset, severe dehydration, hypotension, and petechiae points away from brucellosis. Staphylococcus aureus - Staphylococcus aureus can cause various infections, including sepsis, but a sore throat and the specific presentation of petechiae with hypotension following an apparent upper respiratory tract infection are less characteristic [3]. - While S. aureus can produce toxins leading to toxic shock syndrome, meningococcal sepsis is a more direct fit for the rapid onset and hemorrhagic signs.
Question 5: Which of the following is not a vector-borne disease?
- A. KFD
- B. JE
- C. Brucella (Correct Answer)
- D. Plague
Explanation: ***Brucella*** - **Brucellosis** is primarily transmitted through the consumption of infected, unpasteurized dairy products or direct contact with infected animal tissues, making it a **food-borne** or **contact-borne** disease, not vector-borne. - The bacteria can also be acquired through inhalation of aerosols in occupational settings, but a biological vector is not involved in its transmission to humans. *KFD* - **Kyasanur Forest Disease** (KFD) is a **tick-borne viral hemorrhagic fever** endemic to India. - It is transmitted to humans through the bite of infected ticks, making it a classic example of a **vector-borne disease**. *JE* - **Japanese Encephalitis** (JE) is a **mosquito-borne flaviviral infection** and is the most important cause of viral encephalitis in Asia. - It is transmitted by **Culex mosquitoes**, particularly *Culex tritaeniorhynchus*, confirming its vector-borne nature. *Plague* - **Plague** is a severe bacterial infection caused by *Yersinia pestis*, primarily transmitted to humans through the bites of **infected fleas** (a type of vector). - These fleas often carry the bacteria from infected rodents, making it a definitive **vector-borne disease**.
Question 6: Atrophic dry nasal mucosa, extensive encrustations, and a woody hard external nose are suggestive of which of the following conditions?
- A. Bartonella henselae
- B. Klebsiella pneumoniae (Correct Answer)
- C. Bordetella pertussis
- D. Bacillus anthracis
Explanation: ***Klebsiella pneumoniae*** - This clinical presentation is classic for **rhinoscleroma** (scleroma), a chronic granulomatous infection caused by *Klebsiella pneumoniae* subspecies *rhinoscleromatis*. - Rhinoscleroma presents with a characteristic triad: **atrophic dry nasal mucosa**, **extensive encrustations**, and a **woody hard external nose** due to progressive fibrosis in the sclerotic stage. - The disease progresses through three stages: catarrhal (atrophic with crusts), granulomatous (nodular lesions), and sclerotic (fibrosis causing the woody hardness). - Histologically, it shows **Mikulicz cells** (foamy macrophages containing bacteria) and **Russell bodies**, which are pathognomonic features. *Bacillus anthracis* - Causes **cutaneous anthrax**, which presents with a characteristic **black eschar** (painless necrotic ulcer with surrounding edema), not chronic atrophic changes. - Anthrax causes acute tissue necrosis and edema, not the chronic fibrotic "woody hard" nose seen in rhinoscleroma. - Does not produce extensive encrustations or chronic atrophic nasal mucosa. *Bordetella pertussis* - Causes **whooping cough**, a respiratory tract infection characterized by paroxysmal coughing with an inspiratory "whoop." - Affects the **tracheobronchial tree** causing inflammation and excessive mucus production, not localized nasal pathology. - Does not cause nasal atrophy, encrustations, or external nasal deformities. *Bartonella henselae* - Primarily causes **Cat-Scratch Disease**, presenting with regional lymphadenopathy following cat scratches or bites. - May cause skin papules at inoculation sites and systemic manifestations in immunocompromised patients. - Does not cause chronic nasal pathology, atrophic mucosa, or woody hardness of the nose.
Question 7: Animal to man transmission (zoonosis) is seen in -
- A. Tuberculosis
- B. Measles
- C. Rabies (Correct Answer)
- D. HIV
Explanation: ***Rabies*** - **Rabies** is a classic zoonotic disease, primarily transmitted to humans through the bite or scratch of an infected animal, most commonly **dogs, bats, or other wild carnivores**. - The virus travels from the site of infection to the central nervous system, leading to characteristic neurological symptoms. *Tuberculosis* - While certain strains of **Mycobacterium bovis** can cause zoonotic tuberculosis, the question implies common human tuberculosis (**Mycobacterium tuberculosis**), which is primarily transmitted person-to-person via airborne droplets. - While bovine TB is zoonotic, general "Tuberculosis" in this context usually refers to the human-to-human transmitted form. *Measles* - **Measles** is a highly contagious disease caused by the **measles virus**, which is a **human paramyxovirus**. - It is spread exclusively from **person to person** through respiratory droplets and has no known animal reservoir. *HIV* - **HIV (Human Immunodeficiency Virus)** is thought to have originated from **simian immunodeficiency virus (SIV)** in non-human primates, thus representing a historic zoonotic jump. - However, current and continued transmission of HIV is almost exclusively through **human-to-human contact**, not ongoing animal-to-human transmission.
Question 8: A sewerage worker presents to OPD with acute febrile illness alongwith jaundice and conjunctivitis. His blood sample was taken and sent to lab . Lab findings are suggestive of kidney failure and elevated hepatic enzymes. Which of following is likely diagnosis ?
- A. Leptospirosis (Correct Answer)
- B. Typhoid
- C. Malaria
- D. Hepatitis A
Explanation: ***Leptospirosis*** - The patient's occupation as a **sewerage worker** points to potential exposure to contaminated water, a known risk factor for leptospirosis [1]. - The classic triad of **febrile illness**, **jaundice**, and **conjunctivitis**, combined with **kidney failure** and **elevated hepatic enzymes**, is highly characteristic of severe leptospirosis (Weil's disease) [1], [2]. *Typhoid* - While typhoid can cause fever and, in severe cases, liver dysfunction, it is typically associated with **gastrointestinal symptoms** like abdominal pain and constipation/diarrhea [2]. - **Conjunctivitis** and significant **jaundice** with acute kidney failure are not typical presenting features of typhoid [2]. *Malaria* - Malaria presents with **cyclical fevers**, **chills**, and **sweats**, and can cause jaundice and kidney injury in severe cases [2]. - However, **conjunctivitis** as a prominent symptom is less common, and the distinct occupational exposure makes leptospirosis more likely [1], [2]. *Hepatitis A* - Hepatitis A causes **jaundice** and **elevated hepatic enzymes**, but it is primarily a liver infection and does not typically lead to acute **kidney failure** [3]. - While fever can be present, **conjunctivitis** and rapid progression to kidney failure are not characteristic of Hepatitis A [3].
Question 9: A patient presents with fever and jaundice after repairing sewers. What is the most appropriate test to diagnose the infection in this patient?
- A. Weil Felix test
- B. Paul Bunnell test
- C. Microscopic agglutination test (Correct Answer)
- D. Microimmunofluorescence test
Explanation: ***Microscopic agglutination test*** - The patient's presentation (fever, jaundice, history of repairing sewers) is highly suggestive of **leptospirosis** [1]. The **Microscopic Agglutination Test (MAT)** is considered the gold standard for diagnosing leptospirosis, as it directly detects antibodies against *Leptospira* serovars [1]. - MAT provides **serovar-specific results** and is highly sensitive and specific, especially when acute and convalescent phase sera are tested [1]. *Weil Felix test* - The Weil-Felix test is used to diagnose **rickettsial infections**, not leptospirosis. - It detects antibodies that cross-react with antigens of certain *Proteus* species. *Paul Bunnell test* - The Paul-Bunnell test is used to detect **heterophile antibodies** associated with **infectious mononucleosis** (Epstein-Barr virus infection). - This test is not relevant for diagnosing bacterial infections like leptospirosis. *Microimmunofluorescence test* - The microimmunofluorescence (MIF) test is primarily used for the diagnosis of **chlamydial infections** and sometimes for rickettsial diseases. - While an antibody-detection test, it is not the standard or preferred method for diagnosing leptospirosis.
Question 10: A girl from Shimla presented to OPD with fever, hypotension, malaise and axillary and inguinal lymphadenopathy. Culture in glucose broth shows stalactite growth. Most likely causative organism is?
- A. Yersinia pestis (Correct Answer)
- B. Brucella abortus
- C. Coxiella burnetii
- D. Francisella tularensis
Explanation: ***Yersinia pestis*** - The combination of **fever**, **hypotension**, **malaise**, and **inguinal and axillary lymphadenopathy** (buboes) is highly characteristic of **bubonic plague**, caused by *Yersinia pestis*. - **Stalactite growth** in broth culture is a classic identifying feature of *Yersinia pestis* when incubated without agitation, due to the organism's **lipid A-modified LPS** which allows self-aggregation. *Brucella abortus* - *Brucella abortus* causes **brucellosis**, which presents with **undulant fever**, **arthralgia**, and **hepatosplenomegaly**, but typically not with prominent acute lymphadenopathy and hypotension to this degree. - While it is a **facultative intracellular pathogen**, it does not exhibit stalactite growth in glucose broth. *Coxiella burnetii* - *Coxiella burnetii* causes **Q fever**, which is characterized by **fever**, **headache**, and **pneumonia**, often without prominent lymphadenopathy. - It is an **obligate intracellular bacterium** and cannot be cultivated in standard glucose broth, much less show stalactite growth. *Francisella tularensis* - *Francisella tularensis* causes **tularemia**, which can manifest with **fever**, **lymphadenopathy** (ulceroglandular form), and **malaise**. - However, it typically requires **specialized culture media** like cysteine-enriched agar and does not exhibit stalactite growth in glucose broth.
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