What are the recommended antibiotics, including dosing and duration, for treating community‑acquired pneumonia in a pregnant woman, and which agents should be avoided?

Antibiotic Treatment for Community-Acquired Pneumonia in Pregnancy

β-lactam antibiotics (amoxicillin or ceftriaxone) combined with azithromycin are the preferred first-line agents for treating community-acquired pneumonia in pregnant women, providing safe and effective coverage against the most common bacterial pathogens while avoiding teratogenic agents.

Recommended Antibiotic Regimens by Severity

Outpatient Treatment (Mild Pneumonia)

• Amoxicillin 1 g orally three times daily for 5–7 days is the preferred first-line therapy for previously healthy pregnant women with mild community-acquired pneumonia, as β-lactams are considered safe throughout pregnancy and provide excellent coverage against Streptococcus pneumoniae (the most common pathogen, accounting for 15–20% of cases) 1, 2, 3, 4.
• Add azithromycin 500 mg on day 1, then 250 mg daily for days 2–5 to the amoxicillin regimen if atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae) are suspected or if the patient has comorbidities such as asthma or anemia 1, 2, 3, 4, 5.
• Macrolides (azithromycin, clarithromycin) are safe in pregnancy and effective against atypical organisms, which are common causes of pneumonia in pregnant women 2, 3, 4, 5.

Hospitalized Patients (Moderate to Severe Pneumonia)

• Ceftriaxone 1–2 g IV once daily PLUS azithromycin 500 mg IV or orally daily is the standard regimen for hospitalized pregnant women with moderate-severity pneumonia, providing comprehensive coverage of typical and atypical pathogens 1, 6, 4, 5.
• This combination is safe in pregnancy and addresses the most common bacterial causes: S. pneumoniae, Haemophilus influenzae, and M. pneumoniae 2, 3, 4.
• Alternative β-lactams include cefotaxime 1–2 g IV every 8 hours or ampicillin-sulbactam 3 g IV every 6 hours, always combined with azithromycin 1, 6.

Severe Pneumonia Requiring ICU Admission

• Ceftriaxone 2 g IV daily PLUS azithromycin 500 mg IV daily is mandatory for pregnant women with severe pneumonia requiring ICU care, as combination therapy reduces maternal mortality and morbidity 1, 6, 2.
• Respiratory failure is a serious maternal complication of pneumonia in pregnancy, and prompt intensive care management with appropriate antibiotics has reduced maternal mortality 2, 4.

Antibiotics to Avoid in Pregnancy

Contraindicated Agents

• Fluoroquinolones (levofloxacin, moxifloxacin) should be avoided in pregnancy due to concerns about cartilage and bone development in the fetus, despite their effectiveness against resistant S. pneumoniae 1, 6, 7.
• Doxycycline and tetracyclines are contraindicated in pregnancy because they cause permanent tooth discoloration and inhibit fetal bone growth 1, 4.
• Trimethoprim-sulfamethoxazole should be avoided in the first trimester due to theoretical risk of neural tube defects and in the third trimester due to risk of kernicterus, although it remains the treatment of choice for Pneumocystis pneumonia in HIV-infected pregnant women when benefits outweigh risks 2, 4.

Use with Caution

• Aminoglycosides (gentamicin, tobramycin) should be reserved for severe infections with Pseudomonas or other resistant organisms, as they carry risk of fetal ototoxicity and nephrotoxicity 1, 5.
• Vancomycin should be used only when MRSA coverage is required (e.g., post-influenza pneumonia, cavitary infiltrates), as it crosses the placenta but has not been definitively linked to fetal harm 1, 6, 5.

Duration of Therapy and Monitoring

Treatment Duration

• Minimum 5 days of therapy, continuing until afebrile for 48–72 hours with no more than one sign of clinical instability, with typical duration of 5–7 days for uncomplicated pneumonia 1, 6.
• Extend to 14–21 days if Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli are identified 1, 6.

Transition to Oral Therapy

• Switch from IV to oral antibiotics when the pregnant patient is hemodynamically stable (systolic BP ≥90 mmHg, heart rate ≤100 bpm), clinically improving, afebrile for 48–72 hours, able to tolerate oral intake, and has oxygen saturation ≥90% on room air 1, 6.
• Oral step-down options include amoxicillin 1 g three times daily plus azithromycin 500 mg daily 1, 6.

Special Considerations in Pregnancy

Maternal Risk Factors

• Asthma and anemia increase the risk of contracting pneumonia in pregnancy and should prompt earlier hospitalization and more aggressive treatment 2, 4.
• Antepartum corticosteroids and tocolytic agents also increase pneumonia risk 4.

Neonatal Outcomes

• Pneumonia in pregnancy is associated with low birth weight and increased risk of preterm birth, making prompt diagnosis and treatment critical 2, 4.
• Infants born to mothers with pneumonia are born earlier and weigh less than controls 4.

Viral Pneumonia

• Influenza pneumonia in pregnant women requires antibacterial coverage for superinfection with S. aureus and S. pneumoniae using β-lactams plus azithromycin 4.
• Oseltamivir is safe in pregnancy and should be used for influenza virus infection complicated by pneumonia 4, 5.
• Influenza vaccination during pregnancy reduces respiratory hospitalizations and should be offered to all pregnant women during influenza season 2.

HIV-Infected Pregnant Women

• Trimethoprim-sulfamethoxazole remains the treatment of choice for Pneumocystis pneumonia in HIV-infected pregnant women despite theoretical risks, as mortality remains high without treatment 4.
• Recurrent bacterial pneumonia is more common in HIV-infected pregnant women than in nonpregnant patients 4.

Critical Pitfalls to Avoid

• Never delay antibiotic administration beyond 8 hours after diagnosis, as this increases maternal mortality by 20–30% 1, 6.
• Do not use fluoroquinolone monotherapy in pregnant women, even though it is effective in nonpregnant patients, due to fetal safety concerns 1, 7.
• Avoid macrolide monotherapy in hospitalized pregnant women, as it provides inadequate coverage for typical bacterial pathogens like S. pneumoniae 1, 6.
• Obtain blood and sputum cultures before initiating antibiotics in all hospitalized pregnant women to enable pathogen-directed therapy 1, 6.
• Monitor for respiratory failure closely, as it is a serious maternal complication requiring ICU management 2, 4.