In a 42‑year‑old man with 8 days of fever, neutrophilic leukocytosis (WBC 12 ×10⁹/L), procalcitonin 4.31 ng/mL, bilateral pneumonia on chest X‑ray, mild hepatomegaly, elevated ALT 122 U/L and AST 151 U/L, chronic hepatitis B infection (HBsAg positive, anti‑HBs negative) and currently receiving ceftriaxone, tenofovir, aminoleban and metronidazole, what is the most likely diagnosis, appropriate management, and relevant differential diagnoses?

Diagnosis: Community-Acquired Bacterial Pneumonia with Chronic Hepatitis B Infection

This patient has community-acquired bacterial pneumonia (CAP) as the primary acute illness, with underlying chronic hepatitis B infection that requires concurrent management but is not the cause of his acute febrile presentation.

Primary Diagnosis: Bacterial Pneumonia

The clinical picture strongly supports bacterial CAP:

• Procalcitonin of 4.31 ng/mL strongly indicates bacterial infection 1, 2. Procalcitonin levels >0.5 ng/mL suggest bacterial etiology, and levels >2 ng/mL are highly specific for bacterial pneumonia rather than viral or mycobacterial causes 2.
• Bilateral pneumonia on chest X-ray with neutrophilic leukocytosis (WBC 12 × 10⁹/L with elevated segmenters) confirms active bacterial infection 3.
• 8-day fever with persistent febrile episodes is consistent with inadequately treated bacterial pneumonia 3.
• The bilateral pleural effusions are likely parapneumonic effusions secondary to the pneumonia 3.

Secondary Diagnosis: Chronic Hepatitis B Infection

The hepatitis B profile indicates chronic infection:

• HBsAg positive with anti-HBs <0.01 mIU/mL confirms chronic HBV infection 3.
• Elevated ALT 122 U/L and AST 151 U/L with HBV DNA ≥2,000 IU/mL (presumed based on transaminase elevation) indicates active chronic hepatitis B requiring treatment 3.
• The mild hepatomegaly and hypoalbuminemia (albumin 29 g/L, total protein 48 g/L) suggest chronic liver disease with some degree of hepatic synthetic dysfunction 3.
• Normal PT/INR (0.87,100% activity) indicates no significant cirrhosis at this time 3.

Management Plan

Immediate Pneumonia Management

Continue ceftriaxone for bacterial pneumonia 3. The current regimen is appropriate for CAP:

• Ceftriaxone 2g IV daily should continue for minimum 5 days total, with clinical reassessment 3.
• Discontinue metronidazole – there is no indication for anaerobic coverage in community-acquired pneumonia without aspiration risk 3.
• Monitor clinical response: defervescence, improved oxygenation, and resolution of leukocytosis 3.
• Obtain blood cultures and sputum Gram stain/culture if not already done to guide antibiotic de-escalation 3.

Hepatitis B Management

Continue tenofovir as appropriate first-line therapy for chronic hepatitis B 3:

• Tenofovir disoproxil fumarate (TDF) 300mg daily is a preferred first-line agent with high potency and high barrier to resistance 3, 4.
• Long-term treatment is required – tenofovir should not be stopped after the acute illness resolves 3.
• Obtain HBV DNA quantification, HBeAg, and anti-HBe status to fully characterize the phase of chronic hepatitis B 3.
• Monitor ALT/AST every 3 months initially, then every 6 months once stable 5.

Continue aminoleban (branched-chain amino acids) for nutritional support given hypoalbuminemia, though its primary benefit is in patients with hepatic encephalopathy 3.

Monitoring and Follow-up

During hospitalization:

• Daily clinical assessment for pneumonia resolution (fever curve, respiratory status) 3.
• Repeat CBC to document resolving leukocytosis 3.
• Monitor liver function tests and renal function given dual infection burden 3.
• Assess for complications of pneumonia: parapneumonic effusion requiring drainage, empyema 3.

After discharge:

• Chest X-ray in 6 weeks to confirm pneumonia resolution 3.
• HBV DNA quantification within 1 month to assess virologic response to tenofovir 3.
• Liver ultrasound and AFP every 6 months for hepatocellular carcinoma surveillance given chronic hepatitis B with elevated transaminases 3, 5.
• Consider liver biopsy or transient elastography to stage fibrosis if HBV DNA confirms active replication 3.

Differential Diagnoses to Consider

For the Pneumonia

Tuberculosis – must be excluded given the geographic context and bilateral infiltrates 2:

• Procalcitonin 4.31 ng/mL argues strongly against TB (TB typically has PCT <1 ng/mL) 2.
• However, obtain sputum for acid-fast bacilli smear and culture given 8-day fever duration 2.
• If TB is confirmed, adjust antibiotics and continue tenofovir (active against both HBV and does not interact with TB drugs) 4.

Pneumocystis jirovecii pneumonia (PJP) – less likely but consider if immunocompromised:

• Procalcitonin >4 ng/mL makes PJP unlikely (PJP typically has PCT <2 ng/mL) 2.
• No mention of HIV status – obtain HIV testing given HBV coinfection risk 3.

Secondary bacterial peritonitis – unlikely given normal ascites findings on ultrasound, but:

• If ascites develops, perform diagnostic paracentesis to rule out spontaneous bacterial peritonitis (neutrophils >250/mm³) 3.

For the Liver Disease

Acute-on-chronic liver failure (ACLF) – currently absent:

• Patient has no organ failures (normal creatinine, normal INR, no encephalopathy) 3.
• Bacterial infection is a common precipitant of ACLF in cirrhosis patients 3.
• Monitor closely for development of ACLF during pneumonia treatment: rising creatinine, worsening INR, encephalopathy 3.

Alcohol-related hepatitis – possible contributor:

• AST/ALT ratio of 1.24 (151/122) is not typical for alcoholic hepatitis (usually >1.5) 3.
• Obtain alcohol history and consider if AST:ALT ratio increases 3.

Drug-induced liver injury – consider given multiple medications:

• Ceftriaxone rarely causes hepatotoxicity 3.
• Tenofovir has favorable hepatic safety profile 4, 6.
• Monitor transaminases during treatment 3.

Critical Pitfalls to Avoid

• Do not stop tenofovir after acute illness resolves – chronic HBV requires indefinite treatment until specific stopping criteria are met (HBsAg loss) 3.
• Do not attribute all symptoms to hepatitis B – the procalcitonin elevation and bilateral pneumonia clearly indicate bacterial infection as the acute problem 1, 2.
• Do not overlook tuberculosis in a patient with prolonged fever and bilateral infiltrates, despite elevated procalcitonin 2.
• Monitor for hepatic decompensation during acute bacterial infection, as infection is a major precipitant of ACLF 3.
• Ensure HCC surveillance is established before discharge, as chronic hepatitis B with elevated ALT carries significant HCC risk even without cirrhosis 3, 5.