Hospital Acquired Infections

Hospital Acquired Infections Indian Medical PG Question 1: In a surgical post-op ward, a patient developed wound infection. Subsequently 3 other patients developed similar infections in the ward. What is the most effective way of preventing the spread of infection?

• A. Fumigation of the ward
• B. Wash OT instruments with 1% perchlorate
• C. Proper hand washing of all ward personnel (Correct Answer)
• D. Give IV antibiotics to all patients in the ward

Hospital Acquired Infections Explanation: ***Proper hand washing of all ward personnel*** - **Hand hygiene** is the single most important and effective measure to prevent the spread of **healthcare-associated infections (HAIs)**, especially in a ward where multiple patients are affected. - It directly reduces the transmission of microorganisms from healthcare workers to patients and between patients. *Fumigation of the ward* - **Fumigation** is typically used for **terminal disinfection** or in situations involving highly resistant organisms or outbreaks, but it is not a routine or primary method for preventing day-to-day infection spread. - Its effectiveness is limited, and it can pose **health risks** to personnel and patients if not performed correctly, often requiring the ward to be vacated. *Wash OT instruments with 1% perchlorate* - This option focuses on the **sterilization of operating theater (OT) instruments**, which is crucial for surgical procedures but **irrelevant** to preventing the spread of wound infection within a general ward setting. - The problem describes a ward-based infection spread, not issues with surgical instrument sterility. *Give IV antibiotics to all patients in the ward* - **Prophylactic antibiotics** for all patients in a ward is generally **not recommended** as it can lead to **antibiotic resistance**, mask underlying infections, and cause adverse drug reactions. - Antibiotics should be prescribed judiciously based on specific indications and confirmed infections, not as a general preventive measure.

Hospital Acquired Infections Indian Medical PG Question 2: A frequent traveler presented with 4 days of continuous fever, abdominal pain, and bradycardia. What is the best diagnostic test to confirm the pathogen?

• A. Widal test
• B. Blood culture (Correct Answer)
• C. Urine culture
• D. Stool culture

Hospital Acquired Infections Explanation: ***Blood culture*** - **Blood culture** is the most sensitive and specific test for confirming **typhoid fever** in the first week of illness. - The presence of **continuous fever** (step-ladder pattern), **abdominal pain**, and **relative bradycardia** in a traveler strongly suggests typhoid fever caused by *Salmonella Typhi*. *Widal test* - The **Widal test** detects antibodies against *Salmonella Typhi* antigens and is often positive later in the disease course. - It has **limited sensitivity and specificity**, especially in endemic areas or with prior vaccination, leading to false positives and negatives. *Urine culture* - **Urine culture** has a low yield for *Salmonella Typhi*, as bacteria are intermittently shed in urine, usually later in the disease. - It's primarily useful for diagnosing **urinary tract infections** or in chronic carriers of typhoid. *Stool culture* - **Stool culture** yield is higher in the later stages of typhoid fever, as *Salmonella Typhi* is shed in feces. - Its sensitivity is lower than blood culture in the early acute phase when bacteremia is most prominent.

Hospital Acquired Infections Indian Medical PG Question 3: A patient in the ICU with a central venous catheter (CVC) develops an infection. Microscopy reveals ovoid budding yeast cells. What is the most likely organism?

• A. Candida (Correct Answer)
• B. Staphylococcus epidermidis
• C. Escherichia coli
• D. Staphylococcus aureus

Hospital Acquired Infections Explanation: ***Candida*** - **Gram-positive ovoid budding organisms** are characteristic findings for yeast, with **Candida** species being the most common cause of CVC-related fungal infections in ICU patients. - Patients with CVCs are at high risk for candidemia due to compromised skin barriers and often receiving broad-spectrum antibiotics, which can disrupt the normal flora. *Staphylococcus epidermidis* - This is a **Gram-positive coccus** that grows in clusters and is a common cause of CVC-related **bacterial infections**, developing **biofilms** on catheters. - It does not present as an ovoid budding organism on microscopy. *Escherichia coli* - This is a **Gram-negative rod**, typically associated with **urinary tract infections** and sepsis from an abdominal source. - It would not appear as a Gram-positive ovoid budding organism and is not a common cause of primary CVC-related bloodstream infections unless there's an associated abdominal source. *Staphylococcus aureus* - This is a **Gram-positive coccus** that grows in grape-like clusters and can cause severe CVC-related bloodstream infections, often leading to **endocarditis** or widespread dissemination. - Like *S. epidermidis*, it is a bacterium and does not exhibit ovoid budding.

Hospital Acquired Infections Indian Medical PG Question 4: A diabetic patient developed cellulitis due to S. aureus, which was found to be methicillin resistant on the antibiotic sensitivity testing. All of the following antibiotics will be appropriate except ?

• A. Vancomycin
• B. Teicoplanin
• C. Linezolid
• D. Imipenem (Correct Answer)

Hospital Acquired Infections Explanation: ***Imipenem*** - **Imipenem** is a carbapenem antibiotic that is effective against many Gram-positive and Gram-negative bacteria, but it is **not active against MRSA (methicillin-resistant *Staphylococcus aureus*)**. - MRSA strains are resistant to all beta-lactam antibiotics, including penicillins, cephalosporins, and carbapenems like imipenem, due to the presence of the **mecA gene** which encodes for an altered penicillin-binding protein (PBP2a). *Vancomycin* - **Vancomycin** is a glycopeptide antibiotic that is a primary choice for treating **MRSA infections**, including cellulitis. - It inhibits cell wall synthesis by binding to the D-Ala-D-Ala precursor, preventing cross-linking, and is specifically active against **Gram-positive bacteria**. *Teicoplanin* - **Teicoplanin** is another glycopeptide antibiotic, similar to vancomycin, and is also considered a suitable agent for treating **MRSA infections**. - It works by inhibiting bacterial cell wall synthesis and has a **longer half-life** than vancomycin, allowing for less frequent dosing. *Linezolid* - **Linezolid** is an oxazolidinone antibiotic known for its activity against **Gram-positive bacteria**, including **MRSA** and vancomycin-resistant enterococci (VRE). - It inhibits protein synthesis by binding to the 50S ribosomal subunit, preventing the formation of the initiation complex.

Hospital Acquired Infections Indian Medical PG Question 5: True about chicken pox -

• A. Rash is deep seated
• B. Caused by varicella-zoster virus (Correct Answer)
• C. SAR is 70%
• D. Scab is infective

Hospital Acquired Infections Explanation: ***Caused by varicella-zoster virus*** - Chickenpox, also known as varicella, is definitively caused by the **varicella-zoster virus (VZV)**, a member of the herpesvirus family. - VZV is highly contagious and responsible for both primary infection (chickenpox) and latent infection (shingles). *Rash is deep seated* - The rash of chickenpox is characteristically **superficial**, appearing as vesicles on the epidermis and upper dermis, often described as "dewdrops on a rose petal." - Deep-seated lesions are more characteristic of diseases like **smallpox**, which results in deeper scarring. *SAR is 70%* - The **secondary attack rate (SAR)** for chickenpox in susceptible household contacts is much higher than 70%, typically ranging from **80% to 90%**, highlighting its extreme contagiousness. - This high SAR means that most unvaccinated individuals living with an infected person will contract the disease. *Scab is infective* - While scabs contain the virus, the **infectivity significantly decreases** once the lesions have crusted over and formed scabs. - The most infective stages are typically from 1-2 days before the rash appears until all lesions have crusted.

Hospital Acquired Infections Flashcard 1 of 5

Question: Hospital acquired MRSA is mediated by mecA subtype _____

Answer: I, II, III

Hospital Acquired Infections Flashcard 2 of 5

Question: _____ is a gram negative coccobacillus, obligate aerobe that causes resistant hospital-acquired infections.

Answer: Acinetobacter baumannii

Hospital Acquired Infections Flashcard 3 of 5

Question: mc pathogen involved in hospital aquired infection is _____

Answer: staph aureus

Extra Information: 

Hospital Acquired Infections Flashcard 4 of 5

Question: Enterococcus faecalis is _____ common and less likely to be resistant to vancomycin (more or less)

Answer: more

Hospital Acquired Infections Flashcard 5 of 5

Question: The three major causes of nosocomial infections are _____, Enterobacter, and Serratia

Answer: Klebsiella