Re-emergence of the susceptibility of the Salmonella spp. isolated from blood samples to conventional first line antibiotics

Abstract

BackgroundEnteric fever is an important public health problem in Nepal. Due to emergence of multidrug resistant strains of Salmonella spp. the conventional first-line drugs, ampicillin, chloramphenicol, and cotrimoxazole have not been used as empiric therapy for treatment of enteric fever for last two decades and there have been increased uses of fluoroquinolones as the drugs of choice. The aim of this study was to evaluate and analyze the antimicrobial susceptibility patterns of Salmonella spp.MethodsA total of 620 blood samples collected from the patients suspected of suffering from enteric fever were cultured using standard microbiological techniques. Antibiotic susceptibility testing of the Salmonella spp., was performed by Kirby Bauer disc diffusion technique following Clinical and Laboratory Standard Institute (CLSI) guidelines. Minimum inhibitory concentrations of ciprofloxacin, ofloxacin and nalidixic acid were determined by agar dilution method.ResultsOf the total 83 Salmonella spp., 48 (57.83 %) were S. Typhi and 35 (42.26 %) were S. Paratyphi A. Among 83 Salmonella isolates, 98.8 % of the Salmonella spp. were susceptible to chloramphenicol and co-trimoxazole and about 97.6 % of the isolates were susceptible to ampicillin. Similarly, 69 (83.13 %) isolates were resistant to nalidixic acid. Only 16.9 % of the isolates were susceptible to ciprofloxacin. One S. Typhi isolate was multidrug resistant.ConclusionThe present study revealed the decreased susceptibility of the S. Typhi and S. Paratyphi A to fluoroquinolones, proving them to be inappropriate for empirical therapy for the treatment of enteric fever in our setting. Further the higher susceptibility of the isolates to first line drugs, ampicillin, chloramphenicol, and cotrimoxazole suggests the possibility of using these drugs for empirical therapy.

Antimicrobial resistance trend of Salmonella typhi and paratyphi from 2011-2013: A descriptive study from tertiary care hospital of Nepal

“…This demonstrates that ST and SPA are fully susceptible to ceftriaxone. These results are consistent with other studies from Nepal which have shown full susceptibility to ceftriaxone [14][15][16] . An important implication of these fi ndings is that ceftriaxone is a very good choice for empirical treatment of suspected enteric fever.…”

“…They found three isolates of ESBL producing SPA. In contrast to these studies, full susceptibility of isolates to cefotaxime has been documented by Shrestha et al 16 . As ESBL gene is mobile in nature, the mechanism of resistance in ST and SPA may be due to horizontal transfer of ESBL gene.…”

“…A signifi cant decrease in resistance to chloramphenicol and cotrimoxazole has also been reported from Nepal 11,16,18 . Decrease in resistance may again make these antibiotics useful in near future.…”

High-Level Resistance to Ciprofloxacin and Rising MIC to Ceftriaxone and Azithromycin among Enteric Fever Isolates from a Tertiary Care Center, Puducherry, India

“…So Salmonella typhi infections are getting controlled and Salmonella paratyphi A is emerging (Bharmoria and BehariVaish, 2016 Increased use of second line anti-salmonellae drugs and the discontinuation of use of the conventional first line antimicrobial agents for the treatment of the enteric fever for last two decades, probably have led to the reemergence of susceptibility to first line antibiotics. As plasmids are responsible for determining resistance to these first line antibiotics; loss of these resistance determining plasmids, may be the reason for the re-emergence of the sensitive strains (Chand et al, 2014;Shrestha et al, 2016).…”

Prevalence, resistance, and extended-spectrum beta-lactamases among Salmonella from patients in northeast China

“…Nalidixic acid (NAL), ampicillin (AMP), tetracycline (TCY), sulfamethoxazole-trimethoprim (SXT), and chloramphenicol (CHL) used to treat invasive Salmonella infection in the 1970s and 1980s are referred to as conventional first-line antibiotics [4]. Third-generation cephalosporins and fluoroquinolones became primary antibiotics in recent years [5].…”