Patterns of Enteric Fever and Rise of Extensively Drug-Resistant Typhoid in Pakistan

Overview

This study analyzed 464,956 blood cultures from Pakistan (2017–2019), identifying 23,924 Salmonella Typhi and Paratyphi isolates. Extensively drug-resistant (XDR) S. Typhi accounted for 57% of isolates, with highest prevalence in Sindh and among children aged 5–14 years.

Background

Enteric fever, caused by Salmonella enterica serovars Typhi and Paratyphi, remains a significant health burden in low- and middle-income countries, particularly in South Asia. Despite global declines, Pakistan continues to experience high incidence rates, compounded by rising antimicrobial resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) typhoid strains challenge effective treatment, necessitating robust surveillance to guide public health interventions.

Data Highlights

Key Findings

• Extensively drug-resistant (XDR) S. Typhi accounted for 57% of isolates, with a marked increase in 2019, especially in Sindh province.
• The 5–14 years age group had the highest proportion of MDR (46.1%) and XDR (44.2%) S. Typhi cases, followed by children aged 2–4 years.
• S. Typhi isolates showed high resistance to first-line antibiotics including ampicillin, chloramphenicol, cefixime, ciprofloxacin, ceftriaxone, and co-trimoxazole.
• S. Paratyphi isolates remained largely susceptible to most antibiotics except for high ciprofloxacin resistance (85.9%).
• Both S. Typhi and S. Paratyphi isolates were susceptible to azithromycin, imipenem, and meropenem, indicating these as viable treatment options.
• Laboratory network data covered approximately 90% of the population in Sindh and Punjab, providing robust surveillance insights.

Clinical Implications

The high prevalence of XDR S. Typhi necessitates reconsideration of empirical treatment protocols for typhoid fever in Pakistan, favoring antibiotics such as azithromycin and carbapenems. Surveillance using large laboratory networks can effectively monitor resistance trends and guide public health strategies, including vaccination and antimicrobial stewardship. Clinicians should be vigilant for resistance patterns, especially in pediatric populations where disease burden is highest.

Conclusion

This population-based analysis highlights the alarming rise of extensively drug-resistant typhoid fever in Pakistan, predominantly affecting children and concentrated in Sindh province. Continued surveillance and updated treatment guidelines are critical to managing this public health threat.

References

1. SEAP Study 2016-2019 -- Surveillance for Enteric Fever in Asia Project
2. Clinical Laboratory Standards Institute (CLSI) Guidelines