Antimicrobial stewardship principles US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Antimicrobial stewardship principles. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Antimicrobial stewardship principles US Medical PG Question 1: A 64-year-old woman with a past medical history of poorly managed diabetes presents to the emergency department with nausea and vomiting. Her symptoms started yesterday and have been progressively worsening. She is unable to eat given her symptoms. Her temperature is 102°F (38.9°C), blood pressure is 115/68 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for left-sided costovertebral angle tenderness, and urinalysis demonstrates bacteriuria and pyuria. The patient is admitted to the hospital and started on IV ceftriaxone. On day 3 of her hospital stay she is afebrile, able to eat and drink, and feels better. Which of the following antibiotic regimens should be started or continued as an outpatient upon discharge?
- A. Amoxicillin
- B. Nitrofurantoin
- C. Ciprofloxacin
- D. Ceftriaxone
- E. Trimethoprim-sulfamethoxazole (Correct Answer)
Antimicrobial stewardship principles Explanation: ***Trimethoprim-sulfamethoxazole***
- This patient presents with **acute pyelonephritis**, indicated by fever, CVA tenderness, bacteriuria, and pyuria, requiring a 7-14 day course of treatment.
- After 3 days of IV ceftriaxone with clinical improvement, **step-down to oral therapy** is appropriate.
- **Trimethoprim-sulfamethoxazole** is a first-line oral agent for completing treatment of uncomplicated pyelonephritis and is preferred when **local resistance rates are <20%** and no specific resistance data is available.
- It achieves adequate concentrations in renal tissue and is cost-effective for outpatient therapy.
*Amoxicillin*
- **Amoxicillin** is not recommended for pyelonephritis due to **high resistance rates** among common uropathogens like *E. coli* (often >30%).
- It does not achieve adequate concentrations in the renal parenchyma to effectively treat **upper urinary tract infections**.
*Nitrofurantoin*
- **Nitrofurantoin** is concentrated in the bladder and is highly effective for **lower urinary tract infections (cystitis)**.
- It is **contraindicated for pyelonephritis** because it does not reach therapeutic levels in the renal parenchyma or bloodstream.
- Additionally, it should be avoided in patients with impaired renal function.
*Ciprofloxacin*
- **Ciprofloxacin** is also a first-line oral agent for pyelonephritis and would be an appropriate choice for step-down therapy.
- However, when no culture or susceptibility data is available, **TMP-SMX is generally preferred** as an initial oral choice due to concerns about promoting fluoroquinolone resistance and potential adverse effects (tendonitis, QT prolongation, C. difficile).
- Fluoroquinolones are particularly valuable when reserved for cases with known resistance to other agents or specific patient contraindications.
*Ceftriaxone*
- **Ceftriaxone** is an IV third-generation cephalosporin used for initial empiric treatment of acute pyelonephritis in hospitalized patients.
- Once the patient is **clinically stable, afebrile, and tolerating oral intake**, transitioning to oral therapy is standard practice.
- Continued IV therapy as an outpatient is unnecessarily invasive and costly when oral options are effective.
Antimicrobial stewardship principles US Medical PG Question 2: The surgical equipment used during a craniectomy is sterilized using pressurized steam at 121°C for 15 minutes. Reuse of these instruments can cause transmission of which of the following pathogens?
- A. Non-enveloped viruses
- B. Sporulating bacteria
- C. Prions (Correct Answer)
- D. Enveloped viruses
- E. Yeasts
Antimicrobial stewardship principles Explanation: ***Prions***
- Prions are **abnormally folded proteins** that are highly resistant to standard sterilization methods like steam autoclaving at 121°C, making them a risk for transmission through reused surgical instruments.
- They cause transmissible spongiform encephalopathies (TSEs) like **Creutzfeldt-Jakob disease**, where even trace amounts can be highly infectious.
*Non-enveloped viruses*
- Non-enveloped viruses are generally **more resistant to heat and disinfectants** than enveloped viruses but are typically inactivated by recommended steam sterilization protocols.
- Standard autoclaving conditions are effective in destroying most non-enveloped viruses.
*Sporulating bacteria*
- **Bacterial spores**, such as those from *Clostridium* or *Bacillus*, are known for their high resistance to heat and chemicals, but are usually **inactivated by steam sterilization at 121°C** for 15 minutes.
- This method is specifically designed to kill bacterial spores effectively.
*Enveloped viruses*
- Enveloped viruses are the **least resistant to heat and chemical disinfectants** due to their lipid envelope.
- They are readily **inactivated by standard steam sterilization** at 121°C.
*Yeasts*
- **Yeasts** are eukaryotic microorganisms that are typically **susceptible to heat sterilization**.
- They are effectively killed by typical steam autoclaving conditions used for surgical instruments.
Antimicrobial stewardship principles US Medical PG Question 3: A 37-year-old woman with a history of anorectal abscesses complains of pain in the perianal region. Physical examination reveals mild swelling, tenderness, and erythema of the perianal skin. She is prescribed oral ampicillin and asked to return for follow-up. Two days later, the patient presents with a high-grade fever, syncope, and increased swelling. Which of the following would be the most common mechanism of resistance leading to the failure of antibiotic therapy in this patient?
- A. Intrinsic absence of a target site for the drug
- B. Use of an altered metabolic pathway
- C. Production of beta-lactamase enzyme (Correct Answer)
- D. Altered structural target for the drug
- E. Drug efflux pump
Antimicrobial stewardship principles Explanation: ***Production of beta-lactamase enzyme***
- The patient's symptoms of a rapidly worsening infection despite ampicillin treatment suggest the presence of a **beta-lactamase producing organism**. Ampicillin is a **beta-lactam antibiotic** that is inactivated by these enzymes.
- Anorectal abscesses and rapidly progressing soft tissue infections are often caused by **polymicrobial flora**, including staphylococci and enterococci, many of which can produce **beta-lactamase**.
*Intrinsic absence of a target site for the drug*
- While some bacteria inherently lack the target site for certain drugs (e.g., mycoplasma lacking a cell wall, thus being resistant to beta-lactams), this is less likely to be the **most common mechanism of acquired resistance** leading to treatment failure in a typical perianal infection.
- The rapid progression and failed initial treatment point towards an **acquired mechanism of resistance** rather than an intrinsic one.
*Use of an altered metabolic pathway*
- This mechanism, such as altered **folate synthesis pathways** in resistance to trimethoprim-sulfamethoxazole, is less common as the primary mechanism for ampicillin resistance.
- Ampicillin's mechanism of action primarily targets the **bacterial cell wall**, not a metabolic pathway in the same way.
*Altered structural target for the drug*
- This involves modifications to the **penicillin-binding proteins (PBPs)**, which are the targets of beta-lactam antibiotics like ampicillin. While a valid mechanism (e.g., in MRSA), the **production of beta-lactamase** is generally a more widespread and common cause of ampicillin failure, especially in infections involving mixed flora from the perianal region.
- Given the abrupt failure of ampicillin, **beta-lactamase inactivation** is a more immediate and common cause than a rapid mutational change in PBPs.
*Drug efflux pump*
- **Efflux pumps** actively remove antibiotics from the bacterial cell, contributing to resistance against various drug classes.
- While efflux pumps can play a role, the dominant mechanism for resistance to **ampicillin** in many common perianal pathogens is the **enzymatic degradation by beta-lactamases**.
Antimicrobial stewardship principles US Medical PG Question 4: A 42-year-old woman with a history of multiple sclerosis and recurrent urinary tract infections comes to the emergency department because of flank pain and fever. Her temperature is 38.8°C (101.8°F). Examination shows left-sided costovertebral angle tenderness. She is admitted to the hospital and started on intravenous vancomycin. Three days later, her symptoms have not improved. Urine culture shows growth of Enterococcus faecalis. Which of the following best describes the most likely mechanism of antibiotic resistance in this patient?
- A. Increased efflux across bacterial cell membranes
- B. Production of beta-lactamase
- C. Alteration of penicillin-binding proteins
- D. Alteration of peptidoglycan synthesis (Correct Answer)
- E. Alteration of ribosomal targets
Antimicrobial stewardship principles Explanation: ***Alteration of peptidoglycan synthesis***
- **Vancomycin** targets the **D-Ala-D-Ala terminus** on the peptidoglycan precursor, preventing cross-linking during bacterial cell wall synthesis.
- **Vancomycin resistance in Enterococcus faecalis** occurs through acquisition of resistance genes (vanA, vanB) that encode enzymes modifying the peptidoglycan precursor from **D-Ala-D-Ala to D-Ala-D-Lac**.
- This structural change reduces vancomycin's binding affinity by approximately 1000-fold, rendering the antibiotic ineffective.
- The mechanism directly involves **alteration of the peptidoglycan synthesis pathway**, specifically the terminal amino acid residues of the pentapeptide precursor.
*Increased efflux across bacterial cell membranes*
- This mechanism involves **efflux pumps that actively transport antibiotics out of the bacterial cell**, reducing intracellular concentration.
- While efflux pumps contribute to resistance for antibiotics like **tetracyclines, fluoroquinolones, and macrolides**, this is not the primary mechanism of vancomycin resistance in Enterococcus.
*Production of beta-lactamase*
- **Beta-lactamase enzymes** hydrolyze the **beta-lactam ring** of antibiotics like **penicillins and cephalosporins**, rendering them inactive.
- **Vancomycin is a glycopeptide antibiotic, not a beta-lactam**, so its efficacy is not affected by beta-lactamase production.
*Alteration of ribosomal targets*
- This mechanism confers resistance to antibiotics that target **bacterial ribosomes** to inhibit protein synthesis, such as **macrolides, aminoglycosides, and tetracyclines**.
- **Vancomycin acts on cell wall synthesis**, not protein synthesis, so alteration of ribosomal targets is not relevant to vancomycin resistance.
*Alteration of penicillin-binding proteins*
- **Penicillin-binding proteins (PBPs)** are the targets of **beta-lactam antibiotics** (penicillins, cephalosporins, carbapenems).
- Alterations in PBPs cause resistance to beta-lactams, not to vancomycin.
- **Vancomycin does not interact with PBPs**; it binds directly to the D-Ala-D-Ala terminus of peptidoglycan precursors in the cell wall.
Antimicrobial stewardship principles US Medical PG Question 5: An investigator is studying the chemical structure of antibiotics and its effect on bacterial growth. He has synthesized a simple beta-lactam antibiotic and has added a bulky side chain to the molecule that inhibits the access of bacterial enzymes to the beta-lactam ring. The synthesized drug will most likely be appropriate for the treatment of which of the following conditions?
- A. Folliculitis (Correct Answer)
- B. Nocardiosis
- C. Atypical pneumonia
- D. Erythema migrans
- E. Otitis media
Antimicrobial stewardship principles Explanation: ***Folliculitis***
- The bulky side chain provides **steric hindrance** that prevents **staphylococcal beta-lactamases** from accessing and degrading the **beta-lactam ring**.
- This modification creates an **anti-staphylococcal penicillin** (similar to methicillin, nafcillin, or oxacillin), which is effective against **methicillin-sensitive *Staphylococcus aureus* (MSSA)**.
- **Folliculitis** is most commonly caused by *S. aureus*, making this modified beta-lactam an appropriate treatment choice for MSSA-related folliculitis.
- The bulky side chain specifically protects against the **penicillinase** (beta-lactamase) produced by staphylococci.
*Otitis media*
- Otitis media is commonly caused by beta-lactamase-producing organisms like *Haemophilus influenzae* and *Moraxella catarrhalis*.
- However, the beta-lactamases produced by these gram-negative organisms are **not inhibited by bulky side chains** alone.
- Treatment of beta-lactamase-producing *H. influenzae* and *M. catarrhalis* requires **beta-lactamase inhibitors** (such as clavulanic acid combined with amoxicillin), not steric hindrance.
- The mechanism of protection differs: beta-lactamase inhibitors **suicide inhibitors** that bind to the enzyme, whereas bulky side chains provide **physical blocking**.
*Nocardiosis*
- Nocardiosis is caused by *Nocardia* species, which are **aerobic actinomycetes**.
- These bacteria are typically treated with **sulfonamides** (trimethoprim-sulfamethoxazole) for prolonged periods.
- Beta-lactam antibiotics are generally not first-line treatment, as *Nocardia* species often show intrinsic resistance or require specific antibiotic combinations.
*Atypical pneumonia*
- Atypical pneumonia is caused by organisms like *Mycoplasma pneumoniae*, *Chlamydophila pneumoniae*, and *Legionella pneumophila*.
- These organisms lack a **peptidoglycan cell wall**, which is the target of all **beta-lactam antibiotics**.
- Beta-lactams (regardless of modifications) are completely ineffective against atypical pneumonia pathogens.
- Treatment requires **macrolides** (azithromycin), **tetracyclines** (doxycycline), or **fluoroquinolones**.
*Erythema migrans*
- Erythema migrans is the characteristic rash of early **Lyme disease**, caused by *Borrelia burgdorferi*.
- While *Borrelia* is sensitive to certain beta-lactam antibiotics (amoxicillin, ceftriaxone), it does **not produce beta-lactamases**.
- The bulky side chain modification is unnecessary for treating *Borreria* infections, as there is no beta-lactamase to protect against.
- Standard treatment uses doxycycline, amoxicillin, or ceftriaxone—not anti-staphylococcal penicillins.
Antimicrobial stewardship principles US Medical PG Question 6: A 15-year-old boy presents with his father to the urgent care department with a 5-day history of frequent diarrhea, occasionally mixed with streaks of blood. Stool cultures are pending, but preliminary stool samples demonstrate fecal leukocytes and erythrocytes. The patient's vital signs are within normal limits, and he is started on outpatient therapy for presumed Shigella infection. Which of the following was the young man most likely started on?
- A. Oral vancomycin
- B. Oral erythromycin
- C. Oral metronidazole
- D. An oral quinolone
- E. Oral trimethoprim-sulfamethoxazole (TMP-SMX) (Correct Answer)
Antimicrobial stewardship principles Explanation: **Oral trimethoprim-sulfamethoxazole (TMP-SMX)**
- **TMP-SMX** is a traditional first-line treatment for **Shigella infection** in settings where susceptibility is expected or confirmed.
- The patient's presentation with **bloody diarrhea**, **fecal leukocytes**, and **erythrocytes** is classic for **Shigella dysentery**.
- While **resistance rates vary by region**, TMP-SMX remains an appropriate choice when local susceptibility patterns support its use.
- It is cost-effective, well-tolerated, and appropriate for outpatient management of uncomplicated cases.
*Oral vancomycin*
- Vancomycin is specifically used for **Clostridioides difficile infection** and does not treat Shigella.
- It has **poor oral absorption** and no activity against Gram-negative enteric pathogens like Shigella.
*Oral erythromycin*
- Erythromycin is primarily effective against **Campylobacter jejuni** and respiratory pathogens.
- It has **limited activity against Shigella** and resistance rates are high, making it an inappropriate choice.
*Oral metronidazole*
- Metronidazole treats **anaerobic bacteria** and protozoal infections (*Giardia*, *Entamoeba histolytica*).
- It has **no significant activity against Shigella**, a facultative anaerobic Gram-negative bacillus.
*An oral quinolone*
- **Fluoroquinolones** (e.g., ciprofloxacin) are highly effective against Shigella and often used as first-line therapy, particularly in areas with high TMP-SMX resistance.
- They are increasingly preferred in current guidelines due to rising resistance to TMP-SMX.
- However, in the context of empiric outpatient treatment where susceptibility is presumed, **TMP-SMX** may still be chosen initially as a narrower-spectrum, cost-effective option, with fluoroquinolones reserved based on culture results or treatment failure.
Antimicrobial stewardship principles US Medical PG Question 7: A 32-year-old woman is supposed to undergo tooth extraction surgery. Physical examination is unremarkable, and she has a blood pressure of 126/84 mm Hg and regular pulse of 72/min. She takes no medications. Which of the following cardiac conditions would warrant antibiotic prophylaxis to prevent infective endocarditis in this patient?
- A. Hypertrophic obstructive cardiomyopathy (HOCM)
- B. Mitral regurgitation
- C. Past history of infective endocarditis (Correct Answer)
- D. Ventricular septal defect (VSD)
- E. Implantable cardioverter defibrillator (ICD)
Antimicrobial stewardship principles Explanation: ***Past history of infective endocarditis***
- A **history of infective endocarditis** is a definite indication for **antibiotic prophylaxis** before dental procedures that involve manipulation of gingival tissue, periapical region of teeth, or perforation of the oral mucosa due to the high risk of recurrence.
- This condition creates a predisposition to subsequent episodes of endocarditis, even with minor bacteremia.
*Hypertrophic obstructive cardiomyopathy (HOCM)*
- While HOCM is a significant cardiac condition, it is **no longer an indication** for routine infective endocarditis prophylaxis in the absence of other high-risk features like a prosthetic valve.
- Current guidelines have narrowed the criteria for prophylaxis due to the low absolute risk and potential for side effects from antibiotics.
*Mitral regurgitation*
- **Mitral valve regurgitation**, in the absence of a prosthetic valve or a previous history of endocarditis, generally **does not warrant antibiotic prophylaxis** for routine dental procedures.
- Only specific types of valvular heart disease with high risk (e.g., prosthetic valves, certain congenital heart diseases) require prophylaxis.
*Ventricular septal defect (VSD)*
- **Most ventricular septal defects do not require prophylaxis**. Only **unrepaired cyanotic VSD** or **repaired VSD with residual defects adjacent to prosthetic material** would warrant prophylaxis.
- Completely repaired VSDs without residual defects do not require prophylaxis after the initial 6 months post-repair.
- In this case, with an unremarkable physical examination and normal vital signs, there is no indication of cyanotic heart disease.
*Implantable cardioverter defibrillator (ICD)*
- An **implantable cardioverter defibrillator (ICD)** itself is a device and does not inherently increase the risk for infective endocarditis to warrant prophylaxis for dental procedures.
- The risk of infection is primarily associated with the device insertion procedure itself, not with subsequent dental interventions.
Antimicrobial stewardship principles US Medical PG Question 8: A 21-year-old U.S. born first year medical student with no prior hospital or healthcare work presents to the physician for a routine physical exam. The patient is HIV negative, denies drug use, and denies sick contacts. The physician places a purified protein tuberculin test in the patient's right forearm intradermally. What is the proper time to read the test and induration diameter that would indicate a positive test result?
- A. 36 hours and 7mm diameter
- B. 48 hours and 11mm diameter
- C. 72 hours and 16mm diameter (Correct Answer)
- D. 96 hours and 14mm diameter
- E. 24 hours and 18mm diameter
Antimicrobial stewardship principles Explanation: ***72 hours and 16mm diameter***
- The **purified protein derivative (PPD) test** should ideally be read between 48 and 72 hours after administration to allow for the **Type IV hypersensitivity reaction** to fully develop.
- For individuals with no known risk factors for tuberculosis and no prior exposure, an induration of **≥15 mm** is considered a positive result. A 16mm diameter falls within this range.
*36 hours and 7mm diameter*
- **36 hours** is too early to accurately read a PPD test, as the delayed-type hypersensitivity reaction may not have fully manifested.
- A **7mm induration** would generally be considered negative in a low-risk individual, as the threshold for positivity in this group is higher.
*48 hours and 11mm diameter*
- While **48 hours** is within the acceptable window for reading a PPD test, an **11mm induration** is not considered positive for a young, low-risk individual without any predisposing conditions like HIV or organ transplant.
- The threshold for a positive result in this demographic is typically **≥15 mm**.
*96 hours and 14mm diameter*
- **96 hours** (4 days) is generally too late to accurately read a PPD test, as the reaction may begin to fade, leading to a potentially false negative.
- A **14mm induration** is still below the positive threshold of ≥15mm for a low-risk individual.
*24 hours and 18mm diameter*
- **24 hours** is significantly too early to read a PPD test, as the immune response will not have fully developed, leading to unreliable results.
- While **18mm induration** would be a positive result, the timing makes the reading invalid.
Antimicrobial stewardship principles US Medical PG Question 9: A 35-year-old man is brought to the emergency department after experiencing a seizure. According to his girlfriend, he has had fatigue for the last 3 days and became confused this morning, after which he started having uncontrollable convulsions throughout his entire body. He was unconscious throughout the episode, which lasted about 4 minutes. He has not visited a physician for over 10 years. He has smoked one pack of cigarettes daily for 12 years. His girlfriend admits they occasionally use heroin together with their friends. His temperature is 38.8°C (101.8°F), pulse is 93/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. The lungs are clear to auscultation and examination shows normal heart sounds and no carotid or femoral bruits. He appears emaciated and somnolent. There are multiple track marks on both his arms. He is unable to cooperate for a neurological exam. Laboratory studies show a leukocyte count of 3,000/mm3, a hematocrit of 34%, a platelet count of 354,000/mm3, and an erythrocyte sedimentation rate of 27 mm/h. His CD4+ T-lymphocyte count is 84/mm3 (normal ≥ 500). A CT scan of the head is shown. Which of the following is the most appropriate next step considering this patient's CT scan findings?
- A. Pyrimethamine, sulfadiazine, and leucovorin (Correct Answer)
- B. Trimethoprim-sulfamethoxazole
- C. Albendazole
- D. Glucocorticoids
- E. CT-guided stereotactic aspiration
Antimicrobial stewardship principles Explanation: ***Pyrimethamine, sulfadiazine, and leucovorin***
- The patient presents with **immunosuppression** (CD4+ count of 84/mm³), neurological symptoms including a seizure, and CT findings showing **multiple ring-enhancing lesions**, characteristic of **cerebral toxoplasmosis**.
- The recommended treatment for toxoplasmosis in immunocompromised patients is a combination of **pyrimethamine**, **sulfadiazine**, and **leucovorin** to mitigate the hematological side effects of pyrimethamine.
*Trimethoprim-sulfamethoxazole*
- While trimethoprim-sulfamethoxazole (TMP-SMX) is used for toxoplasmosis **prophylaxis** in HIV patients, it is not the first-line treatment for active cerebral toxoplasmosis due to lower efficacy compared to pyrimethamine/sulfadiazine.
- TMP-SMX is the preferred regimen for *Pneumocystis jirovecii pneumonia (PCP)* prophylaxis, which differs from the presentation here.
*Albendazole*
- **Albendazole** is an antihelminthic drug primarily used to treat infections caused by various parasitic worms, such as **neurocysticercosis**.
- The CT findings are more consistent with toxoplasmosis than neurocysticercosis, which often presents with calcified lesions in chronic cases or cysts in various stages.
*Glucocorticoids*
- **Glucocorticoids** (e.g., dexamethasone) are often used in conjunction with antimicrobial therapy for cerebral toxoplasmosis to reduce **cerebral edema** and mass effect, especially if there is significant inflammation or herniation risk.
- However, glucocorticoids alone are not a definitive treatment as they do not address the underlying parasitic infection and can exacerbate immunosuppression.
*CT-guided stereotactic aspiration*
- **Biopsy (CT-guided stereotactic aspiration)** is typically reserved for cases where the diagnosis of cerebral toxoplasmosis is uncertain, or if there is no clinical or radiological improvement after 1–2 weeks of empiric antitoxoplasmal therapy.
- Given the classic presentation in an immunocompromised patient, empiric treatment is the initial appropriate step, rather than immediate biopsy, to avoid invasive procedures if unnecessary.
Antimicrobial stewardship principles US Medical PG Question 10: An 11-year-old girl is brought to the emergency department because of high-grade fever, headache, and nausea for 3 days. She avoids looking at any light source because this aggravates her headache. She has acute lymphoblastic leukemia and her last chemotherapy cycle was 2 weeks ago. She appears lethargic. Her temperature is 40.1°C (104.2°F), pulse is 131/min and blood pressure is 100/60 mm Hg. Examination shows a stiff neck. The pupils are equal and reactive to light. Neck flexion results in flexion of the knee and hip. Muscle strength is decreased in the right upper extremity. Deep tendon reflexes are 2+ bilaterally. Sensation is intact. Extraocular movements are normal. Two sets of blood cultures are obtained. Which of the following is the most appropriate next step in management?
- A. Acyclovir therapy
- B. Antibiotic therapy (Correct Answer)
- C. MRI of the brain
- D. CT scan of the head
- E. Lumbar puncture
Antimicrobial stewardship principles Explanation: ***Antibiotic therapy***
- This patient presents with **fever, headache, stiff neck, photophobia, and positive Brudzinski's sign (neck flexion results in flexion of the knee and hip)**, which are classic signs of **meningitis**. Given her history of **acute lymphoblastic leukemia (ALL)** and recent chemotherapy, she is **immunocompromised** and at high risk for **bacterial meningitis**, a life-threatening infection requiring immediate antibiotic treatment.
- Due to the severity of symptoms and the high risk in an immunocompromised patient, immediate initiation of empiric, broad-spectrum antibiotics is crucial after obtaining blood cultures, even before definitive diagnosis from cerebrospinal fluid (CSF) analysis.
*Acyclovir therapy*
- **Acyclovir** is an antiviral medication used to treat herpes simplex virus (HSV) or varicella-zoster virus (VZV) encephalitis or meningitis.
- While viral meningitis is a possibility, bacterial meningitis is a more urgent and severe concern in an immunocompromised patient with these neurological signs, making immediate antibiotics a higher priority.
*MRI of the brain*
- An **MRI of the brain** provides detailed imaging of brain structures and can detect abscesses, tumors, or inflammation.
- However, in acute meningitis, especially with signs of increased intracranial pressure (which should be ruled out before LP), antibiotics are the most immediate and critical intervention, and an MRI would delay this life-saving treatment.
*CT scan of the head*
- A **CT scan of the head** is primarily used to rule out **mass lesions, hydrocephalus, or significant cerebral edema** before performing a **lumbar puncture (LP)** in patients with suspected meningitis who have focal neurological deficits or signs of increased intracranial pressure.
- While it may be considered before LP due to the focal neurological deficit (decreased muscle strength in the right upper extremity), administering antibiotics takes precedence due to the high suspicion of bacterial meningitis in an immunocompromised patient.
*Lumbar puncture*
- A **lumbar puncture** is essential for diagnosing meningitis by analyzing the **cerebrospinal fluid (CSF)** for cell count, glucose, protein, and culture.
- However, performing an LP can be delayed if there are signs of increased intracranial pressure (which warrants a preceding CT scan) or if the patient's condition is unstable; importantly, **empiric antibiotics should be started immediately** in a suspected bacterial meningitis case, especially in an immunocompromised patient, and not delayed for imaging or LP.
More Antimicrobial stewardship principles US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
