Internal Medicine
1 questionsWhat is the most common form of leptospirosis?
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 661: What is the most common form of leptospirosis?
- A. Icteric form
- B. Hepatorenal form
- C. Anicteric form (Correct Answer)
- D. Weil's disease
Explanation: ***Anicteric form*** - The **anicteric form** accounts for about 90% of all leptospirosis cases, presenting with milder, flu-like symptoms without jaundice. - Patients typically experience **fever, headache, myalgia**, and conjunctival suffusion during the initial septicemic phase [1], followed by an immune phase that can involve meningitis or uveitis [1]. *Icteric form* - The **icteric form** (Weil's disease) is a severe manifestation, characterized by jaundice, renal failure, and hemorrhage, occurring in a minority of cases (5-10%). - Although more severe and often life-threatening, it is **less common** than the anicteric presentation [1]. *Hepatorenal form* - This term describes the severe complications of leptospirosis, including **liver and kidney dysfunction**, specifically associated with Weil's disease. - While a critical aspect of severe leptospirosis, it is a description of the organ involvement rather than a distinct common form of the disease. *Weil's disease* - **Weil's disease** is the most severe and potentially fatal form of leptospirosis, characterized by **jaundice, renal failure, hemorrhage, and myocarditis**. - It is a severe subset of the icteric form, making it a very serious but **uncommon variant** of the overall disease.
Microbiology
8 questionsOil paint appearance on nutrient agar is seen in -
What is the most common age group affected by Streptococcus pyogenes?
Naegler's reaction is due to:
Disruption of which of the following oropharyngeal commensals predisposes to candidiasis?
Primary complex of M bovis involves:
Brill-Zinsser disease is a recrudescent form of which infection?
Listeria escapes from phagosomes (phagolysosomes) due to:
Which bacteria can grow even in the presence of antiseptics?
NEET-PG 2015 - Microbiology NEET-PG Practice Questions and MCQs
Question 661: Oil paint appearance on nutrient agar is seen in -
- A. Staphylococcus aureus (Correct Answer)
- B. Streptococcus pyogenes
- C. Bordetella pertussis
- D. H. influenzae
Explanation: ***Staphylococcus aureus*** - *Staphylococcus aureus* forms characteristic **golden-yellow, smooth, opaque colonies** on nutrient agar with a **buttery or creamy consistency** - Some texts describe this appearance as **"oil paint-like"** due to the pigmented, smooth, and glistening surface that can resemble brushed paint - Colonies are typically **2-4 mm in diameter**, round, and show **golden pigmentation** (due to carotenoid pigments) - On **blood agar**, *S. aureus* shows **beta-hemolysis** with golden colonies *Streptococcus pyogenes* - *Streptococcus pyogenes* grows poorly on plain nutrient agar and requires **enriched media** like blood agar - On blood agar, it forms **small, translucent, grey-white colonies** surrounded by a wide zone of **beta-hemolysis** - Colonies are typically **pinpoint** in size and do not show pigmentation *Bordetella pertussis* - *Bordetella pertussis* is a **fastidious organism** that does **not grow on plain nutrient agar** - Requires specialized enriched media like **Bordet-Gengou agar** (with potato-glycerol-blood) or **Regan-Lowe agar** - On Bordet-Gengou agar, colonies appear as **small, smooth, pearl-like** or **"mercury droplet"** colonies after 3-7 days *H. influenzae* - *Haemophilus influenzae* is also fastidious and requires **X factor (hemin)** and **V factor (NAD)** for growth - Does **not grow on plain nutrient agar** - On **chocolate agar**, forms **small, smooth, translucent, greyish colonies** with a characteristic musty odor - Colonies are typically **1-2 mm** in diameter
Question 662: What is the most common age group affected by Streptococcus pyogenes?
- A. 30-40 years
- B. <5 years
- C. 5-15 years (Correct Answer)
- D. 20-25 years
Explanation: ***5-15 years*** - **Streptococcus pyogenes** (Group A Strep) commonly causes **pharyngitis** (strep throat), which primarily affects school-aged children. - This age group is more susceptible due to increased exposure in school and daycare settings. *<5 years* - While younger children can get strep infections, it is less common in those under **3 years of age**, as viral etiologies are more prevalent for pharyngitis in this group. - They are more prone to **non-streptococcal bacterial infections** and certain viral infections. *20-25 years* - Although adults can get **Streptococcus pyogenes** infections, the incidence significantly decreases after childhood. - Pharyngitis in this age group is more often **viral** in origin. *30-40 years* - The prevalence of **Streptococcus pyogenes** infections, particularly pharyngitis, is typically low in this age group compared to children. - Infections, if they occur, may stem from exposure to infected children or close contact environments.
Question 663: Naegler's reaction is due to:
- A. Lecithinase (Correct Answer)
- B. Coagulase
- C. Hyaluronidase
- D. None of the options
Explanation: ***Lecithinase*** - The **Naegler reaction** is a bacterial identification test used to detect the production of **lecithinase** (also known as alpha-toxin) by certain bacteria, particularly *Clostridium perfringens*. - This enzyme hydrolyzes **lecithin** (a lipid found in egg yolk), resulting in a visible opaque precipitate around the bacterial colonies on egg yolk agar. *Coagulase* - **Coagulase** is an enzyme produced by some bacteria (e.g., *Staphylococcus aureus*) that causes the coagulation of blood plasma. - While it is an important virulence factor, it is not involved in the **Naegler reaction**. *Hyaluronidase* - **Hyaluronidase** is an enzyme that breaks down **hyaluronic acid**, a component of connective tissue, facilitating the spread of bacteria. - It is often referred to as a **spreading factor** but is not detected by the **Naegler reaction**. *None of the options* - This option is incorrect because **Lecithinase** is directly responsible for the **Naegler reaction**.
Question 664: Disruption of which of the following oropharyngeal commensals predisposes to candidiasis?
- A. Staphylococcus
- B. Streptococcus (Correct Answer)
- C. Lactobacillus
- D. Haemophilus influenzae
Explanation: ***Streptococcus*** - **Streptococcus** species, particularly *S. sanguinis* and *S. mitis*, are major commensals in the oral cavity that **inhibit the growth of *Candida albicans*** through competition for nutrients and production of antimicrobial substances. - Disruption of this normal **streptococcal flora**, often by broad-spectrum antibiotics, creates an environment where *Candida albicans* can proliferate, leading to candidiasis. *Staphylococcus* - **Staphylococcus** species are primarily skin and nasal commensals; while *S. aureus* can be found in the oral cavity, it is not a primary competitor against *Candida* in the same way as streptococci. - Their presence or absence is not typically a direct predisposing factor for oral candidiasis compared to the dominant streptococcal flora. *Lactobacillus* - **Lactobacillus** species are common in the gastrointestinal tract and vagina, where they maintain an acidic environment that inhibits pathogen growth; however, they are less dominant in the oropharynx as a defense against *Candida*. - While beneficial for overall host health, their disruption in the oral cavity does not typically precipitate candidiasis as directly as that of the **streptococcal flora**. *Hemophilus influenzae* - *Haemophilus influenzae* is a common inhabitant of the **upper respiratory tract** and can be an opportunistic pathogen, but it is not known to have a significant role in directly inhibiting *Candida* growth in the oropharynx. - Its presence or absence in the commensal flora in the oral cavity does not typically influence the development of candidiasis.
Question 665: Primary complex of M bovis involves:
- A. Tonsil and skin
- B. Tonsil and intestine (Correct Answer)
- C. Tonsil and lung
- D. Skin and Intestine
Explanation: ***Tonsil and intestine*** - *Mycobacterium bovis* is primarily transmitted through **consumption of contaminated milk and dairy products**, making the **alimentary tract** the main route of infection - The primary complex (Ghon complex) involves the **initial site of infection plus regional lymph nodes** - In alimentary tuberculosis, the organisms enter through the **intestinal mucosa** (Peyer's patches) or **tonsillar tissue**, creating foci with associated mesenteric or cervical lymphadenopathy - Both tonsils and intestines are part of the **alimentary system**, representing the typical primary complex for M. bovis in humans *Tonsil and lung* - This incorrectly combines **two different routes of entry** (alimentary and respiratory) - A primary complex involves a **single portal of entry**, not multiple unrelated organ systems - While M. bovis can rarely cause pulmonary TB through inhalation, this would create a separate lung + hilar node complex, not a combined tonsil-lung complex *Tonsil and skin* - **Skin involvement** requires direct inoculation through cuts or abrasions and does not form a primary complex with tonsillar infection - These represent different portals of entry and would not occur together as a primary complex *Skin and Intestine* - **Skin infection** by M. bovis is rare and requires occupational exposure with direct inoculation (e.g., veterinarians, butchers) - This incorrectly pairs two different routes of infection that would not form a single primary complex
Question 666: Brill-Zinsser disease is a recrudescent form of which infection?
- A. Recrudescence of R prowazekii infection (Correct Answer)
- B. Recrudescence of R typhi infection
- C. None of the options
- D. Recrudescence of Coxiella burnetii infection
Explanation: **Recrudescence of R prowazekii infection** - Brill-Zinsser disease is a **late-onset complication** of **epidemic typhus**, caused by *Rickettsia prowazekii*. - It occurs years after the initial infection, due to **reactivation of dormant bacteria** in the body. *Recrudescence of R typhi infection* - *Rickettsia typhi* causes **murine typhus**, but its recrudescent form is not referred to as Brill-Zinsser disease. - Murine typhus is typically a **milder disease** compared to epidemic typhus. *Recrudescence of Coxiella burnetii infection* - *Coxiella burnetii* causes **Q fever**, which can have a chronic form but is not a recrudescence of a typhus infection. - Q fever presents with different clinical manifestations, such as **endocarditis** or **hepatitis**, not typically a rash or neurological symptoms seen in typhus. *None of the options* - This option is incorrect because the specific recrudescent form described in the question clearly points to *Rickettsia prowazekii*.
Question 667: Listeria escapes from phagosomes (phagolysosomes) due to:
- A. Opacity associated protein (OAP)
- B. Caspases
- C. Cell membrane adhesion molecules
- D. beta-hemolysin (Correct Answer)
Explanation: ***beta-hemolysin*** - *Listeria monocytogenes* produces **listeriolysin O (LLO)**, a **beta-hemolysin**, which is a pore-forming toxin that lyses the phagosomal membrane. - This allows the bacteria to escape into the host cell cytoplasm, thus **avoiding destruction** by lysosomal enzymes and neutralizing the microbicidal environment. *Caspases* - **Caspases** are a family of proteases that play essential roles in programmed cell death (apoptosis) and inflammation. - While bacteria can manipulate host cell apoptosis, caspases themselves are **host enzymes** and do not directly confer resistance to phagosome destruction. *Cell membrane adhesion molecules* - **Adhesion molecules** facilitate bacterial attachment to host cells and internalisation, but they do not directly provide a mechanism for **escaping the phagosome** once internalised. - Examples include internalins, which are involved in bacterial entry into cells. *Opacity associated protein (OAP)* - **Opacity associated proteins (OAPs)** are primarily associated with *Neisseria gonorrhoeae* and are involved in adherence to host cells and evasion of the immune response. - They are not a mechanism for **phagosomal escape** or directly related to *Listeria's* intracellular survival.
Question 668: Which bacteria can grow even in the presence of antiseptics?
- A. Staphylococcus
- B. Streptococcus
- C. E. coli
- D. Pseudomonas (Correct Answer)
Explanation: ***Pseudomonas*** - **Pseudomonas aeruginosa** is unique among common bacteria in its ability to not just survive but actually **grow in the presence of antiseptics**. - It can multiply in **quaternary ammonium compounds**, **chlorhexidine solutions**, and even **distilled water** due to minimal nutritional requirements. - Resistance mechanisms include **efflux pumps**, **biofilm formation**, and **low outer membrane permeability** that exclude many antiseptic agents. - This characteristic makes it a notorious cause of **hospital-acquired infections** and contaminant of disinfectant solutions. *Staphylococcus* - While some strains like **MRSA (methicillin-resistant Staphylococcus aureus)** are resistant to many antibiotics, they are generally **susceptible to common antiseptics**. - Standard antiseptics like alcohols, iodophors, and chlorhexidine effectively kill Staphylococcus species. *Streptococcus* - **Streptococcus species** are generally **susceptible to most common antiseptics and disinfectants**. - They are known for causing infections like strep throat and cellulitis but do not exhibit antiseptic resistance. *E. coli* - **Escherichia coli** is typically **susceptible to standard antiseptic agents**. - While some strains can be antibiotic-resistant, their resistance mechanisms do not generally extend to antiseptics, unlike **Pseudomonas**.
Pediatrics
1 questionsAt what age group is Streptococcus pneumoniae pneumonia most commonly observed?
NEET-PG 2015 - Pediatrics NEET-PG Practice Questions and MCQs
Question 661: At what age group is Streptococcus pneumoniae pneumonia most commonly observed?
- A. < 5 years (Correct Answer)
- B. 5 - 15 years
- C. 20 - 25 years
- D. 30 - 40 years
Explanation: ***< 5 years*** - *Streptococcus pneumoniae* pneumonia is particularly common and severe in **young children**, especially those under the age of 5, due to their developing immune systems. - This age group has a higher incidence of **invasive pneumococcal disease**, including pneumonia and meningitis, making vaccination crucial. *5 - 15 years* - While pneumonia can occur in this age group, it is **less common** than in very young children or older adults. - The immune system is generally more developed and effective at this age, leading to a **lower incidence** of severe pneumococcal infections. *20 - 25 years* - This age group generally has a robust immune system, making *Streptococcus pneumoniae* pneumonia **uncommon** unless there are underlying risk factors such as immunocompromise or chronic medical conditions. - Most cases of pneumonia in young adults are often due to **viral pathogens** or *Mycoplasma pneumoniae*. *30 - 40 years* - Similar to the 20-25 years age group, incidence of *Streptococcus pneumoniae* pneumonia remains **relatively low** in healthy individuals in their 30s and 40s. - Increased risk is typically associated with **chronic illnesses**, smoking, or conditions that weaken the immune system.