Investigation of Antimicrobial Susceptibility of Salmonella spp. Isolated from Hospitalized Patients with Diarrhea

Objectives: Rising antimicrobial resistance is a global challenge; however, resistance patterns may vary substantially by region and even by serovar. The lack of contemporary, serovar-specific data in regions such as Iraq complicates the development of evidence-based treatment strategies. This study aimed to address this gap by characterizing a localized non-typhoidal Salmonella outbreak. Materials and Methods: Between April and November 2019, stool and blood samples were collected from patients. Samples were cultured on appropriate media and tested serologically. Salmonella identification was confirmed using biochemical tests and the VITEK® 2 automated identification system. Antimicrobial susceptibility testing was performed using Mueller-Hinton agar in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Serotyping was conducted at the Central Public Health Laboratory in Baghdad Results: Samples were collected from 450 patients. Salmonella spp. were isolated in 75 (16.6%) patients. Among Salmonella-positive patients, the highest proportion was observed in the 1–10-year age group (40%), and Salmonella brandenburg was the most frequently identified serotype (61.3%). All isolates were susceptible to ceftriaxone, ciprofloxacin, and imipenem, while 77.3% were resistant to amikacin. Conclusion: Our findings reveal a distinct local epidemiological pattern in Baghdad, characterized by a transient outbreak of S. brandenburg in 2019 that was not detected in subsequent surveillance. Clinically, isolates from this non-typhoidal outbreak were fully susceptible to ceftriaxone, in contrast to the concurrent national epidemic of highly ceftriaxone-resistant Salmonella typhi. This dual epidemiological pattern, together with the high rate of amikacin resistance, underscores the critical importance of continuous, localized, and serovar-specific surveillance to guide effective public health strategies in Iraq. Keywords: Salmonella spp., serotyping, antibiotic susceptibility, gastroenteritis