Article

Antimicrobial susceptibility to azithromycin among Salmonella enterica isolates from the United States.

National Antimicrobial Resistance Monitoring System, Centers for Disease Control and Prevention, CCID/NCZVED/DFBMD/EDLB, 1600 Clifton Road, Atlanta, GA 30329, USA.
Antimicrobial Agents and Chemotherapy (impact factor: 4.84). 06/2011; 55(9):3985-9. DOI:10.1128/AAC.00590-11 pp.3985-9
Source: PubMed

ABSTRACT Due to emerging resistance to traditional antimicrobial agents, such as ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol, azithromycin is increasingly used for the treatment of invasive Salmonella infections. In the present study, 696 isolates of non-Typhi Salmonella collected from humans, food animals, and retail meats in the United States were investigated for antimicrobial susceptibility to azithromycin. Seventy-two Salmonella enterica serotype Typhi isolates from humans were also tested. For each isolate, MICs of azithromycin and 15 other antimicrobial agents were determined by broth microdilution. Among the non-Typhi Salmonella isolates, azithromycin MICs among human isolates ranged from 1 to 32 μg/ml, whereas the MICs among the animal and retail meat isolates ranged from 2 to 16 μg/ml and 4 to 16 μg/ml, respectively. Among Salmonella serotype Typhi isolates, the azithromycin MICs ranged from 4 to 16 μg/ml. The highest MIC observed in the present study was 32 μg/ml, and it was detected in three human isolates belonging to serotypes Kentucky, Montevideo, and Paratyphi A. Based on our findings, we propose an epidemiological cutoff value (ECOFF) for wild-type Salmonella of ≤16 μg/ml of azithromycin. The susceptibility data provided could be used in combination with clinical outcome data to determine tentative clinical breakpoints for azithromycin and Salmonella enterica.

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Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

ampicillin
 
antimicrobial agents
 
antimicrobial susceptibility
 
azithromycin MICs
 
clinical outcome data
 
epidemiological cutoff value
 
highest MIC
 
humans
 
invasive Salmonella infections
 
non-Typhi Salmonella
 
Paratyphi A
 
retail meats
 
Salmonella enterica
 
Salmonella enterica serotype Typhi
 
Salmonella serotype Typhi
 
serotypes Kentucky
 
susceptibility data
 
tentative clinical breakpoints
 
traditional antimicrobial agents
 
wild-type Salmonella
 

Maria Sjölund-Karlsson