In vitro activity of azithromycin in Salmonella isolates from Pakistan

Abstract

Introduction: Enteric fever is caused by Salmonella enterica serovars Typhi and Paratyphi A, B and C. It is a significant public health issue in Pakistan, which is exacerbated by a high level of resistance some isolates display to drugs routinely used in treatment. Azithromycin may be a treatment option for such isolates. Methodology: We determined the minimum inhibitory concentrations (MICs) of Salmonella Typhi and Paratyphi isolates against azithromycin in an attempt to gauge its feasibility as a therapeutic option. The MICs were also compared with corresponding disc diffusion zone sizes to see if there was consistency between the two tests. We tested 45 Salmonella enterica isolates using E-tests for MIC detection and azithromycin discs with a concentration of 15µg/ml for disc diffusion testing. Results: Salmonella Typhi, Salmonella Paratyphi A, and Salmonella Paratyphi C isolates demonstrated MICs of 2-12mg/L against azithromycin, suggesting that the antibiotic could be used for therapeutic purposes. For Salmonella Paratyphi B, the MICs were 2-48 mg/L. The higher MIC indicates a need for caution when considering use of azithromycin for Salmonella Paratyphi B infections without first testing for the MIC. There was a close correlation between MICs and zone sizes which was statistically significant. Conclusions: Our results indicate azithromycin is a potential therapeutic option for enteric fever. Standardized laboratory testing methods and interpretation for azithromycin against Salmonella enterica would allow laboratories to report upon this antibiotic with confidence.

Simplex PCR Assay for Detection of blaTEM and gyrA Genes, Antimicrobial Susceptibility Pattern and Plasmid Profile of Salmonella spp. Isolated from Stool and Raw Meat Samples in Niger State, Nigeria

“…causes salmonellosis, among other diseases and are also predominant cause of human foodborne outbreaks and diseases in tropical and sub-tropical countries leading to public health threats [1]. In order to facilitate treatment, recommended therapeutic regimen for Salmonella infections were based on the use of ampicillin, chloramphenicol and trimethoprim/ sulfamethoxazole [2], however there had been the emergence of resistance resulting in great impairment of the efficacy of these antibiotics treatment options [3].…”

Clinical Efficacy of Azithromycin Versus Ciprofloxacin in Treatment of Typhoid Fever in Children

“…Salmonella Typhi and Paratyphi A and C isolates had a mean inhibitory concentration (MIC) of azithromycin that indicates it could be utilised for therapeutic purposes. 12 A study conducted in 2009 suggests that fluoroquinolones (ciprofloxacin, ofloxacin) and azithromycin are almost equal in clinical efficacy in treatment of typhoid fever. 6 However a study conducted in 2011 suggests that fluoroquinolones are found to be superior than other recent antibiotics (azithromycin, cephalosporins).…”

“…It was shown by the minimum inhibitory concentration (MIC) of Salmonella Typhi, Paratyphi A and Paratyphi C when they were exposed to azithromycin that it may have promise for use in therapeutic settings. 12 According to the findings of a study that was carried out in 2009, the clinical efficacy of fluoroquinolones (such as ciprofloxacin and ofloxacin) and azithromycin in the treatment of typhoid fever is practically same. 6 NA Trivedi and others 14 intended to evaluate the quality of the evidence that supports the preference of azithromycin for the treatment of uncomplicated typhoid fever over the other medicines.…”

A study of antibiogram of Salmonella enterica serovar Typhi isolates from

“…19,20 The reason for therapeutic response is the high intracellular concentrations achieved by azithromycin of up to 50 to 100 times that in serum. 19,21,22 Despite this, continuing treatment without taking in to consideration the laboratory MIC results is fraught with problems. Although S. Typhi is a predominately intracellular bacteria, it is estimated that one-third of bacterial cells in the blood are extracellular.…”