Treatment of Japanese patients with enteric fever using azithromycin and MIC levels for causative organisms

Area of Science:

• Infectious Diseases
• Pharmacology
• Microbiology

Background:

• Enteric fever, caused by Salmonella Typhi and Salmonella Paratyphi, is a significant public health concern.
• Fluoroquinolone resistance in enteric fever pathogens necessitates alternative treatment options.
• Azithromycin (AZM) is used in Japan for drug-resistant enteric fever, but optimal dosing and efficacy are not well-established.

Purpose of the Study:

• To evaluate the clinical effectiveness and safety of oral azithromycin (AZM) for treating enteric fever in Japanese patients.
• To determine the minimum inhibitory concentrations (MICs) of AZM against causative organisms.
• To assess appropriate treatment regimens for azithromycin in this patient population.

Main Methods:

• A case series study involving 6 Japanese patients (5 adults, 1 child) diagnosed with enteric fever (4 typhoid, 2 paratyphoid).
• Patients were treated with oral azithromycin using two different regimens: (1) 1000 mg day 1 followed by 500 mg daily for 5-6 days, or (2) 500 mg daily for 10 days.
• Minimum inhibitory concentrations (MICs) of AZM against Salmonella isolates were determined using E-test.

Main Results:

• Good clinical responses were observed in all 5 adult patients treated with azithromycin.
• Treatment failure occurred in the single pediatric patient with typhoid fever.
• No adverse reactions were reported during the study period. AZM MICs ranged from 4 to 32 µg/mL against the isolated pathogens.

Conclusions:

• Oral azithromycin appears to be a potentially effective and safe treatment option for adult Japanese patients with enteric fever.
• The effectiveness of azithromycin may differ between adult and pediatric populations, warranting further investigation.
• Further research is needed to optimize azithromycin dosing and confirm its role in managing fluoroquinolone-resistant enteric fever.