Comparison of Single vs Combination Drug Therapy in Extensively Drug Resistant Salmonella typhi: An Observational Study from Pakistan

INTRODUCTION: Antibiotic resistance has become a significant problem in typhoid fever due to the emergence of extensively drug resistant (XDR) Salmonella enterica serovar typhi. In Pakistan, an outbreak of ceftriaxone-resistant typhoid was first reported in November 2016. METHODS: A retrospective chart review was conducted at Liaquat National Hospital and Medical University, in Karachi, Pakistan. Patient records were identified from the microbiology laboratory data of all admitted patients who had blood culture positive for XDR Salmonella typhi from January 2017 to December 2019. RESULTS: Out of 254 patients, 179 (70%) were male with an average age of 11.7 ± 10.9 years. Around 190 (74%) patients were treated with combination therapy, 126 (49%) were given azithromycin and meropenem and 61 (24%) received azithromycin and imipenem. A total of 64 (25%) patients received single drug therapy, 33 (12%) were given azithromycin, 23 (9%) meropenem, and 8 (3%) imipenem. Analysis indicated that single drug therapy resulted in an earlier onset of defervescence compared with combination therapy (5.03±2.98 days vs 3.45±2.48 days; P <0.001), with a decreased occurrence of pancytopenia (P <0.001). CONCLUSION: Single antimicrobial therapy achieved defervescence earlier than combination therapy, with carbapenems performing better than azithromycin.