Meningococcal disease US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Meningococcal disease. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Meningococcal disease US Medical PG Question 1: An 18-year-old girl is brought to the emergency department because of a 1-day history of severe headache with photophobia and diffuse myalgias. She is a college student and lives in a dormitory in a large urban area. She has not traveled recently. On arrival, she is lethargic. Her temperature is 39.3°C (102.7°F), pulse is 120/min, and blood pressure is 88/58 mm Hg. Examination shows scattered petechiae and ecchymoses on the trunk and lower extremities. There is decreased range of motion of the neck. Cerebrospinal fluid analysis shows a cell count of 1,600/μL (80% neutrophils) and a lactate concentration of 5.1 mmol/L. Which of the following is most likely to have prevented this patient's condition?
- A. Intravenous vancomycin
- B. Polysaccharide conjugate vaccine (Correct Answer)
- C. Erythromycin therapy
- D. Doxycycline therapy
- E. Toxoid vaccine
Meningococcal disease Explanation: ***Polysaccharide conjugate vaccine***
- This patient presents with symptoms highly suggestive of **bacterial meningitis** and **septic shock**, likely caused by *Neisseria meningitidis*, given the petechiae, ecchymoses, and rapid deterioration.
- A **meningococcal conjugate vaccine** would have provided protection against most common serogroups of *N. meningitidis* (A, C, W-135, Y) and is strongly recommended for college students living in dormitories due to increased risk of transmission.
*Intravenous vancomycin*
- This is an **acute treatment** for bacterial meningitis, specifically active against *Streptococcus pneumoniae* and some resistant strains.
- It would not have **prevented** the condition; preventative measures are typically vaccines or prophylactic antibiotics.
*Erythromycin therapy*
- Erythromycin is an antibiotic used for various bacterial infections, including atypical pneumonia and some skin infections.
- It is **not the primary prophylactic agent** for meningococcal disease and would not have prevented this specific condition.
*Doxycycline therapy*
- Doxycycline is a broad-spectrum antibiotic used for a range of infections, including tick-borne diseases and certain respiratory infections.
- It is **not indicated for the prevention** of meningococcal meningitis.
*Toxoid vaccine*
- **Toxoid vaccines** protect against diseases caused by bacterial toxins, such as tetanus and diphtheria.
- *Neisseria meningitidis* causes disease primarily through direct invasion and immune response to its capsular polysaccharides, not primarily exotoxins, so a toxoid vaccine would not be effective here.
Meningococcal disease US Medical PG Question 2: A 15-year-old female is brought to the emergency room with high fever and confusion. She complains of chills and myalgias, and physical examination reveals a petechial rash. Petechial biopsy reveals a Gram-negative diplococcus. The patient is at greatest risk for which of the following?
- A. Pelvic inflammatory disease
- B. Septic arthritis
- C. Bilateral adrenal destruction (Correct Answer)
- D. Osteomyelitis
- E. Acute endocarditis
Meningococcal disease Explanation: ***Bilateral adrenal destruction***
- The clinical presentation with **high fever, confusion, myalgias, and a petechial rash**, along with the finding of **Gram-negative diplococci** from a petechial biopsy, strongly indicates **meningococcemia** (*Neisseria meningitidis* infection).
- **Waterhouse-Friderichsen syndrome**, a severe complication of meningococcemia, involves **massive bilateral adrenal hemorrhage** leading to acute adrenal insufficiency.
*Pelvic inflammatory disease*
- This is an infection of the female reproductive organs, often caused by *Chlamydia trachomatis* or *Neisseria gonorrhoeae*, and typically presents with lower abdominal pain, vaginal discharge, and fever, not usually with a widespread petechial rash and confusion.
- While *Neisseria gonorrhoeae* is a Gram-negative diplococcus, the systemic symptoms and petechial rash point to a disseminated infection like meningococcemia, not localized PID.
*Septic arthritis*
- Septic arthritis involves bacterial infection of a joint, leading to pain, swelling, and reduced range of motion in that specific joint.
- Although disseminated gonococcal infection can cause septic arthritis, the primary presentation with confusion and a rapidly progressive petechial rash points to a more severe systemic infection like meningococcemia.
*Osteomyelitis*
- Osteomyelitis is an infection of the bone, characterized by localized pain, tenderness, swelling, and fever, often without the rapid onset of confusion and widespread petechial rash.
- While it can be caused by various bacteria, including some Gram-negative organisms, it's not the most likely acute complication of the described systemic infection.
*Acute endocarditis*
- Acute endocarditis is an infection of the heart's inner lining or valves, often caused by bacteria like *Staphylococcus aureus*, leading to symptoms such as fever, new heart murmurs, and embolic phenomena.
- While systemic symptoms and petechiae can occur, confusion and a rapidly spreading rash, coupled with the specific Gram-negative diplococcus finding, more strongly suggest meningococcal sepsis over acute endocarditis.
Meningococcal disease US Medical PG Question 3: An 18-year-old female college student is brought to the emergency department by ambulance for a headache and altered mental status. The patient lives with her boyfriend who is with her currently. He states she had not been feeling well for the past day and has vomited several times in the past 12 hours. Lumbar puncture is performed in the emergency room and demonstrates an increased cell count with a neutrophil predominance and gram-negative diplococci on Gram stain. The patient is started on vancomycin and ceftriaxone. Which of the following is the best next step in management?
- A. Treat boyfriend with rifampin (Correct Answer)
- B. Add ampicillin to treatment regimen
- C. Add ampicillin, dexamethasone, and rifampin to treatment regimen
- D. Add dexamethasone to treatment regimen
- E. Treat boyfriend with ceftriaxone and vancomycin
Meningococcal disease Explanation: ***Treat boyfriend with rifampin***
- The patient's presentation with headache, altered mental status, neutrophilic pleocytosis, and **Gram-negative diplococci** on CSF Gram stain is highly suggestive of **Neisseria meningitidis** meningitis.
- The patient is already on appropriate empiric antibiotic therapy (vancomycin and ceftriaxone), so the **immediate priority** is to prevent secondary cases through **post-exposure prophylaxis** for close contacts.
- Close contacts, including household members like the boyfriend, are at high risk of contracting the infection and should receive prophylaxis within **24 hours** of case identification, with **rifampin**, **ciprofloxacin**, or **IM ceftriaxone** being standard options.
*Add ampicillin to treatment regimen*
- Ampicillin provides coverage for **Listeria monocytogenes**, but the Gram stain demonstrating **Gram-negative diplococci** makes Listeria (Gram-positive rod) unlikely in this otherwise healthy young adult without specific risk factors for Listeria.
- The current regimen of vancomycin and ceftriaxone provides adequate empiric coverage for acute bacterial meningitis, targeting common pathogens like **S. pneumoniae** and **N. meningitidis**.
*Add ampicillin, dexamethasone, and rifampin to treatment regimen*
- While providing rifampin prophylaxis to the boyfriend is appropriate, adding it to the **patient's** treatment regimen is not indicated for her active infection.
- **Dexamethasone** is often added to reduce inflammation and neurological sequelae but should be given **prior to or concurrently** with the first dose of antibiotics; adding it later in the course may not be as beneficial.
- This option conflates treatment of the patient with prophylaxis of contacts.
*Add dexamethasone to treatment regimen*
- Dexamethasone is recommended in adults with suspected pneumococcal meningitis to reduce mortality and neurological sequelae, but ideal administration is **prior to or with the first dose of antibiotics**.
- While it might still be considered, the priority given the **Gram-negative diplococci** (suggesting N. meningitidis rather than S. pneumoniae) is **contact prophylaxis** to prevent further spread, and the timing for optimal dexamethasone benefit has likely passed.
*Treat boyfriend with ceftriaxone and vancomycin*
- Ceftriaxone and vancomycin are appropriate for treating the patient's active meningitis, but they are not the standard or preferred agents for **post-exposure prophylaxis** in contacts.
- Post-exposure prophylaxis typically involves a short course of agents like **rifampin**, **ciprofloxacin**, or a single dose of **intramuscular ceftriaxone**, primarily to eradicate nasopharyngeal carriage and prevent transmission.
Meningococcal disease US Medical PG Question 4: A 13-year-old boy is brought to the emergency department because of a 2-day history of fever, headache, and irritability. He shares a room with his 7-year-old brother, who does not have any symptoms. The patient appears weak and lethargic. His temperature is 39.1°C (102.4°F) and blood pressure is 99/60 mm Hg. Physical examination shows several purple spots over the trunk and extremities. A lumbar puncture is performed. Gram stain of the cerebrospinal fluid shows numerous gram-negative diplococci. Administration of which of the following is most likely to prevent infection of the patient's brother at this time?
- A. Penicillin G
- B. Rifampin (Correct Answer)
- C. Conjugated vaccine
- D. Doxycycline
- E. Cephalexin
Meningococcal disease Explanation: ***Rifampin***
- The patient has bacterial meningitis due to **Neisseria meningitidis**, identified by the gram-negative diplococci and classic symptoms (fever, headache, irritability, petechiae).
- **Rifampin** is commonly used for **chemoprophylaxis** against *N. meningitidis* in close contacts due to its excellent penetration into saliva and nasopharyngeal secretions, effectively eradicating carriage.
*Penicillin G*
- While **Penicillin G** is an effective treatment for established meningococcal meningitis, it is **not appropriate for prophylaxis** due to its poor penetration into respiratory secretions and its inability to reliably eradicate the nasopharyngeal carriage of *N. meningitidis*.
- Its use for prophylaxis would mainly target systemic infection rather than preventing transmission from a carrier state.
*Conjugated vaccine*
- The **meningococcal conjugated vaccine** provides active immunity against specific serogroups of *N. meningitidis*.
- However, it requires time for an immune response to develop and is therefore **not effective for immediate post-exposure prophylaxis** in a household contact.
*Doxycycline*
- **Doxycycline** is a broad-spectrum antibiotic but is **not the preferred agent for meningococcal prophylaxis**.
- Its primary uses include atypical bacterial infections, tick-borne diseases, and some sexually transmitted infections, rather than *N. meningitidis* chemoprophylaxis.
*Cephalexin*
- **Cephalexin** is a first-generation cephalosporin primarily used for skin and soft tissue infections and some urinary tract infections.
- It has **limited activity against *N. meningitidis*** and is not recommended for either treatment or prophylaxis of meningococcal disease.
Meningococcal disease US Medical PG Question 5: A 4-day-old newborn is brought to the physician because of a generalized rash for 1 day. He was born at term. The mother had no prenatal care and has a history of gonorrhea, which was treated 4 years ago. The newborn is at the 50th percentile for head circumference, 60th percentile for length, and 55th percentile for weight. His temperature is 36.8°C (98.2°F), pulse is 152/min, and respirations are 51/min. Examination shows an erythematous maculopapular rash and pustules with an erythematous base over the trunk and extremities, sparing the palms and soles. The remainder of the examination shows no abnormalities. Which of the following is the most likely diagnosis?
- A. Congenital syphilis
- B. Acropustulosis
- C. Milia
- D. Erythema toxicum (Correct Answer)
- E. Pustular melanosis
Meningococcal disease Explanation: **Erythema toxicum**
- Erythema toxicum is a **benign, self-limited rash** commonly seen in newborns, characterized by an **erythematous maculopapular rash** with pustules on an erythematous base.
- The rash typically appears on the **trunk and extremities**, sparing the palms and soles, and is generally asymptomatic, matching the presentation in this 4-day-old infant.
*Congenital syphilis*
- Congenital syphilis would typically present with a rash that can involve the **palms and soles**, and is often accompanied by other systemic signs like **hepatosplenomegaly**, rhinitis, or skeletal abnormalities, which are absent here.
- Although the mother had no prenatal care and a history of gonorrhea, no specific risk factors or clinical signs of congenital syphilis are present in the newborn's history or examination.
*Acropustulosis*
- Infantile acropustulosis is characterized by **recurrent crops of pruritic vesicles and pustules** predominantly on the **palms and soles**, which is contrary to the described sparing of these areas.
- This condition typically presents with significant **itching**, which is not mentioned in the newborn's presentation.
*Milia*
- Milia consists of **tiny, pearly white or yellow papules** that are typically found on the face, especially the nose and cheeks, and are essentially clogged pores.
- They are **not erythematous** and do not present as a generalized maculopapular rash with pustules on an erythematous base.
*Pustular melanosis*
- Transient neonatal pustular melanosis is characterized by pustules that rupture to leave a **collarette of scale** and then hyperpigmented macules, without an erythematous base.
- The lesions are usually present at birth, and the characteristic residual hyperpigmented macules are a key diagnostic feature, which is not described.
Meningococcal disease US Medical PG Question 6: A 34-year-old woman presents with confusion, drowsiness, and headache. The patient’s husband says her symptoms began 2 days ago and have progressively worsened with an acute deterioration of her mental status 2 hours ago. The patient describes the headaches as severe, localized to the frontal and periorbital regions, and worse in the morning. Review of symptoms is significant for a mild, low-grade fever, fatigue, and nausea for the past week. Past medical history is significant for HIV infection for which she is not currently receiving therapy. Her CD4+ T cell count last month was 250/mm3. The blood pressure is 140/85 mm Hg, the pulse rate is 90/min, and the temperature is 37.7°C (100.0°F). On physical examination, the patient is conscious but drowsy. Papilledema is present. No pain is elicited with extension of the leg at the knee joint. The remainder of the physical examination is negative. Laboratory findings, including panculture, are ordered. A noncontrast CT scan of the head is negative and is followed by a lumbar puncture. CSF analysis is significant for:
Opening pressure 250 mm H2O (70-180 mm H2O)
Glucose 30 mg/dL (40-70 mg/dL)
Protein 100 mg/dL (<40 mg/dL)
Cell count 20/mm3 (0-5/mm3)
Which of the following additional findings would most likely be found in this patient?
- A. Gram-positive diplococci are present on microscopy
- B. CSF shows a positive acid-fast bacillus stain
- C. Multiple ring-enhancing lesions are seen on a CT scan
- D. CSF shows gram negative diplococci
- E. CSF India ink stain shows encapsulated yeast cells (Correct Answer)
Meningococcal disease Explanation: ***CSF India ink stain shows encapsulated yeast cells***
- The patient's presentation with **subacute meningitis symptoms** (headache, confusion, low-grade fever) in the setting of **untreated HIV infection** with a low CD4+ count (250/mm3) strongly suggests an opportunistic infection.
- The CSF findings of **elevated opening pressure**, **low glucose**, **high protein**, and **moderate pleocytosis** are classic for **cryptococcal meningitis**, for which the India ink stain is diagnostic for encapsulated yeast cells.
*Gram-positive diplococci are present on microscopy*
- This finding suggests **bacterial meningitis**, specifically caused by organisms like *Streptococcus pneumoniae*.
- While bacterial meningitis presents acutely with severe symptoms, the **subacute course** and moderate pleocytosis are less typical, and the patient's immune status points towards an opportunistic infection.
*CSF shows a positive acid-fast bacillus stain*
- A positive **acid-fast bacillus (AFB) stain** in CSF would indicate **tuberculous meningitis**.
- While tuberculous meningitis can present subacutely with similar CSF findings in HIV patients, it typically involves a more significant lymphocytic pleocytosis and a more pronounced chronic course than suggested by the acute worsening.
*Multiple ring-enhancing lesions are seen on a CT scan*
- **Multiple ring-enhancing lesions** on CT or MRI are characteristic of **Toxoplasma encephalopathy** or **CNS lymphoma** in HIV-positive patients.
- While these are common HIV-related CNS complications, the patient's primary presentation points to **meningitis** (inflammation of meninges with CSF abnormalities) rather than focal brain lesions without meningeal involvement.
*CSF shows gram negative diplococci*
- **Gram-negative diplococci** in CSF suggest **meningococcal meningitis** (*Neisseria meningitidis*).
- This typically presents as an **acute, severe bacterial meningitis** with rapid deterioration, usually in immunocompetent individuals or specific outbreaks, which doesn't align with the subacute onset and specific CSF profile for cryptococcus.
Meningococcal disease US Medical PG Question 7: A 4-year-old boy is brought to the emergency department by his parents. He is lethargic and confused and has a severe headache, vomiting, and a high-grade fever since earlier that day. His mother reports that the child was doing well until 2 days ago when he developed a fever and green nasal discharge. The patient has a history of neonatal sepsis, meningococcemia at 18 months of age, and pneumococcal pneumonia at 2 and 3 years of age. His scheduled vaccinations are up to date. His blood pressure is 70/50 mm Hg, heart rate is 120/min, respiratory rate is 22/min, and temperature is 39.3°C (102.4°F). On examination, the child is lethargic and his skin is pale, with several petechiae over his buttocks. There is a purulent nasal discharge from both nostrils. The lungs are clear to auscultation bilaterally. Heart sounds are normal. There is marked neck rigidity. Cerebrospinal fluid analysis shows the following results:
Opening pressure 100 mm H2O
Appearance cloudy
Protein 500 mg/dL (5 g/L)
White blood cells 2500/μL (polymorphonuclear predominance)
Glucose 31 mg/dL (1.7 mmol/L)
Culture positive for N. meningitidis
Which of the following immunological processes is most likely to be impaired in this child?
- A. Formation of C5-9 complex (Correct Answer)
- B. Production of IL-2 by Th1 cells
- C. Oxidative burst in macrophages
- D. Activation of TCRs by MHC-II
- E. Cleavage of C2 component of complement into C2a and C2b
Meningococcal disease Explanation: ***Formation of C5-9 complex***
- The recurrent infections with **encapsulated bacteria** like *N. meningitidis* and *S. pneumoniae*, along with recurrent **meningococcemia**, strongly suggest a deficiency in the **terminal complement pathway (C5-C9)**, which is crucial for forming the **membrane attack complex (MAC)**.
- The MAC is essential for **lysing gram-negative bacteria** such as *N. meningitidis*, and a defect here increases susceptibility to recurrent infections by this pathogen.
*Production of IL-2 by Th1 cells*
- **Interleukin-2 (IL-2)** is vital for **T-cell proliferation** and differentiation, particularly of **cytotoxic T lymphocytes (CTLs)**, important for viral and intracellular bacterial infections.
- While important for overall immune function, a deficiency in IL-2 production does not specifically or primarily explain recurrent encapsulated bacterial infections and meningococcemia.
*Oxidative burst in macrophages*
- The **oxidative burst** is critical for phagocytic cells (neutrophils and macrophages) to kill ingested pathogens, especially **catalase-positive bacteria** and fungi.
- A defect here (e.g., in **chronic granulomatous disease**) leads to recurrent severe bacterial and fungal infections, typically forming granulomas, which is not the specific pattern observed with recurrent meningococcal disease.
*Activation of TCRs by MHC-II*
- **T-cell receptor (TCR)** activation by **MHC-II** is central to **CD4+ helper T cell** function, essential for coordinating immune responses and antibody production.
- While critical for adaptive immunity, a defect here would lead to broader immune deficiencies, including impaired antibody responses and susceptibility to various pathogens, but does not preferentially predispose to recurrent *N. meningitidis* infections like terminal complement deficiency.
*Cleavage of C2 component of complement into C2a and C2b*
- The cleavage of **C2** is part of the **classical and lectin complement pathways**, which are important for opsonization and inflammation.
- **C2 deficiency** is often associated with recurrent pyogenic infections and autoimmune diseases (e.g., SLE), but not specifically with recurrent infections by *N. meningitidis*, which is more characteristic of **terminal complement component deficiencies**.
Meningococcal disease US Medical PG Question 8: Blood cultures are sent to the laboratory and empiric treatment with intravenous vancomycin is started. Blood cultures grow gram-negative bacilli identified as Cardiobacterium hominis. Which of the following is the most appropriate next step in management?
- A. Switch to intravenous gentamicin
- B. Switch to intravenous ampicillin
- C. Switch to intravenous ceftriaxone (Correct Answer)
- D. Switch to intravenous cefazolin
- E. Add intravenous rifampin
Meningococcal disease Explanation: ***Switch to intravenous ceftriaxone***
- **Cardiobacterium hominis** is part of the **HACEK group** of bacteria, which are known for causing **endocarditis**.
- These organisms are typically susceptible to **beta-lactam antibiotics**, with **third-generation cephalosporins** like ceftriaxone being the drug of choice due to their excellent activity and good penetration.
*Switch to intravenous gentamicin*
- While **aminoglycosides** like gentamicin can be used in combination regimens for serious infections, they are generally **not monotherapy** for HACEK endocarditis and are associated with **nephrotoxicity** and **ototoxicity**.
- The primary treatment for HACEK endocarditis is a **beta-lactam antibiotic**, not an aminoglycoside alone.
*Switch to intravenous ampicillin*
- **Ampicillin** is a beta-lactam, but it may not consistently provide optimal coverage for all HACEK organisms, and some strains may have reduced susceptibility.
- **Third-generation cephalosporins** are preferred due to their broader and more consistent activity against this group.
*Switch to intravenous cefazolin*
- **Cefazolin** is a first-generation cephalosporin and typically has **limited activity** against gram-negative bacilli, especially those like Cardiobacterium hominis which require broader-spectrum beta-lactams.
- Its spectrum of activity is primarily against **gram-positive bacteria** and some **gram-negative cocci**.
*Add intravenous rifampin*
- **Rifampin** is primarily used for **mycobacterial infections** and in combination regimens for specific bacterial infections (e.g., bone and joint infections, prosthetic device infections) often due to resistant staphylococci.
- It is **not a first-line agent** for Cardiobacterium hominis infections and there's no indication for its use here with an organism susceptible to ceftriaxone.
Meningococcal disease US Medical PG Question 9: A 2-year-old girl who emigrated from Pakistan 2 weeks ago is brought to the emergency department because of lower limb weakness for one-day. One week ago, she had a 3-day episode of flu-like symptoms that resolved without treatment. She has not yet received any routine childhood vaccinations. Deep tendon reflexes are 1+ in the right lower extremity and absent in the left lower extremity. Analysis of cerebrospinal fluid shows a leukocyte count of 38 cells/mm3 (68% lymphocytes), a protein concentration of 49 mg/dL, and a glucose concentration of 60 mg/dL. Which of the following is the most likely diagnosis in this patient?
- A. Poliomyelitis (Correct Answer)
- B. Tetanus
- C. Guillain-Barre syndrome
- D. Botulism
- E. HSV encephalitis
Meningococcal disease Explanation: ***Poliomyelitis***
- The patient's presentation with **acute flaccid paralysis** (lower limb weakness with absent reflexes), recent emigration from a region with potential **endemic polio** (Pakistan), and **lack of vaccination** are highly suggestive of poliomyelitis.
- The **CSF findings** (mild pleocytosis with lymphocytic predominance and normal glucose) are consistent with a viral infection of the central nervous system, which is characteristic of polio.
*Tetanus*
- Tetanus typically presents with **spastic paralysis**, muscle rigidity, and **lockjaw**, not flaccid paralysis.
- The onset of symptoms is also usually preceded by a wound contamination, which is not mentioned in this case.
*Guillain-Barre syndrome*
- While GBS can cause **flaccid paralysis** and is often preceded by a viral illness, it typically presents with **ascending paralysis** and the CSF classically shows **albumino-cytological dissociation** (high protein with normal or low cell count), which is not fully consistent with the CSF findings here.
- The rapid onset of significant asymmetry in reflexes is also less typical for GBS.
*Botulism*
- Botulism causes **descending flaccid paralysis**, often starting with cranial nerve palsies (e.g., ptosis, diplopia), and is typically associated with ingestion of contaminated food or honey in infants.
- The patient's symptoms are more focused on lower limb weakness without initial cranial nerve involvement, and the CSF findings are usually normal in botulism.
*HSV encephalitis*
- HSV encephalitis typically presents with **fever, seizures, altered mental status, and focal neurological deficits**, not primarily acute flaccid paralysis.
- While it is a viral encephalitis, the predominant symptom pattern and the specific lower limb weakness are not characteristic of HSV encephalitis.
Meningococcal disease US Medical PG Question 10: A 24-hour-old newborn presents to the emergency department after a home birth because of fever, irritability alternating with lethargy, and poor feeding. The patient’s mother says symptoms acutely onset 12 hours ago and have not improved. No significant past medical history. His mother did not receive any prenatal care, and she had rupture of membranes 20 hours prior to delivery. His vital signs include: heart rate 150/min, respiratory rate 65/min, temperature 39.0°C (102.2°F), and blood pressure 60/40 mm Hg. On physical examination, the patient has delayed capillary refill. Laboratory studies show a pleocytosis and a low glucose level in the patient’s cerebrospinal fluid. Which of the following is the most likely causative organism for this patient’s condition?
- A. Group A Streptococcus
- B. Enterovirus
- C. Group B Streptococcus (Correct Answer)
- D. Streptococcus pneumoniae
- E. Cryptococcus neoformans
Meningococcal disease Explanation: ***Group B Streptococcus***
- This newborn presents with **fever, irritability/lethargy, poor feeding**, and signs of **sepsis (tachycardia, tachypnea, hypotension, delayed capillary refill)**, along with **abnormal CSF (pleocytosis, low glucose)**, indicating **neonatal meningitis**.
- **Group B Streptococcus (GBS)** is the **most common cause of early-onset neonatal sepsis and meningitis**, especially with risk factors such as **lack of prenatal care** and **prolonged rupture of membranes (>18 hours)**, as seen in this case.
*Group A Streptococcus*
- While Group A Streptococcus can cause severe infections, it is an **uncommon cause of neonatal sepsis and meningitis** compared to GBS.
- More typically associated with **pharyngitis, impetigo, and necrotizing fasciitis** in older children and adults.
*Enterovirus*
- Enteroviruses are a common cause of **viral meningitis in neonates and infants**, but typically present with a **lymphocytic pleocytosis** and **normal CSF glucose**, in contrast to the features (pleocytosis, low glucose) seen here.
- While fever and irritability can be present, the CSF findings point more towards a bacterial infection.
*Streptococcus pneumoniae*
- *Streptococcus pneumoniae* can cause bacterial meningitis but is **less common in the immediate neonatal period** (first 7 days of life) compared to GBS.
- Risk factors often include **preterm birth** or **underlying immune deficiencies**, which are not specified here.
*Cryptococcus neoformans*
- *Cryptococcus neoformans* is an **opportunistic fungal pathogen** that typically causes meningitis in **immunocompromised individuals**, such as those with HIV/AIDS.
- It is **extremely rare** in immunocompetent newborns and would not be the most likely cause in this clinical scenario.
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