Trends of Enteric Fever and Emergence of Extensively Drug-Resistant Typhoid in Pakistan: Population-Based Laboratory Data From 2017–2019

Background. Typhoid fever burdens low- and middle-income countries, especially children. Despite being curable, it now resists first-line antibiotics. This study aims to understand antimicrobial resistance patterns associated with multidrug-resistant (MDR) and extensively drug-resistant (XDR) typhoid fever cases in Pakistan. Methods. We conducted a retrospective review of blood culture–confirmed typhoid cases from 5 large laboratory networks in Pakistan over a period of 3 years (2017–2019). Data were analyzed for 464 956 blood culture specimens, of which Typhi and Paratyphi were isolated in 23 924 (5%) of all blood cultures done. Results. Sindh had the highest proportion of S. Typhi cases (72%) of all positive cases, followed by Punjab with 46.9%. The 5–14-years age group had the highest proportion of S. Typhi (MDR: 46.1%; XDR: 44.2%), followed by the 2–4-years age group (MDR: 27%; XDR: 26.2%). XDR isolates of S. Typhi were found in 57%. Most S. Typhi isolates were resistant to ampicillin (79.8%), chloramphenicol (80.8%), cefixime (64.6%), ciprofloxacin (66.4%), ceftriaxone (63.3%), and co-trimoxazole (80.2%). Most S. Paratyphi isolates were responsive to antibiotics, ampicillin (97.2%), chloramphenicol (98.6%), cefixime (99.5%), ceftriaxone (99.5%), and co-trimoxazole (98.7%). Resistance to ciprofloxacin was 85.9%. Both S. Typhi and S. Paratyphi were susceptible to azithromycin and imipenem, whereas 99.8% of S. Typhi and 100% of S. Paratyphi were sensitive to meropenem. Conclusions. Increased prevalence of culture-confirmed XDR S. Typhi cases was observed in 2019 as compared with 2017, presumably due to the outbreak of XDR in Sindh.