Trends in antimicrobial susceptibility and serotype distribution of nontyphoidalSalmonella from chickens in four European countries during 1998–2004

Abstract number: 1134_03_242

Jong A., Friederichs S.


In many countries, nontyphoidalSalmonella is a leading cause of food-borne illness in humans. Salmonellosis is usually self-limiting but antimicrobial treatment is recommended for severe illness, with fluoroquinolones and third-generation cephalosporins as drugs of choice. As concern was raised recently regarding poultry as a major source of fluoroquinolone-resistant Salmonella spp., a surveillance comprising two large EU regions was conducted.


In one programme, caecal samples were randomly taken at a Belgian slaughterhouse from chickens raised in Belgium, France or the Netherlands. Caecal contents of 5 birds were pooled to provide a single sample per flock. In another, carcass meat samples were collected from chickens processed in several processing plants across Germany. In total, 2856 Salmonella strains were isolated. Standardized susceptibility testing to ciprofloxacin (CP) and nalidixic acid (NA) as well as non-quinolones including ampicillin (AM), cefotaxime (CT), chloramphenicol (CA), gentamicin (GM), streptomycin (S), tetracycline (TE) and trimethoprim/sulfadiazine (TS) was performed by agar dilution. Resistance was assessed, if applicable, using NCCLS criteria.


In all, 52 different serotypes were identified. The serotype prevalences differed strikingly between the two geographical areas as well as in time. In both programmes, resistance to CP was absent, except for one isolate (MIC 4mg/ml). Decreased susceptibility was apparent but did not deteriorate, as indicated by stable CP MIC90 values around 0.25 mg/ml, and 32 and 9 % resistance to NA. Among the serotypes with decreased susceptibility S. hadar, S. virchow, S. blockley and S. paratyphi B were relatively the most frequent. In contrast, resistance to AM, S, TE and TS amounted to 46, 27, 33 and 18 % in the Belgian collection and to 16, 11, 16 and 12 % in Germany. CA resistance was 8 and 4%, respectively; GM resistance did not exceed 1 % in both programmes. Of 1832 isolates thus far tested for CT susceptibility, none have been resistant (MIC 50/90 of 0.12 to 0.25 mg/ml).


Resistance among Salmonella spp. from chickens varied for non-quinolones from 0 % for CT to considerable higher rates for some older drugs, while resistance to CP, particularly important for treating invasive salmonellosis in humans, approached zero. Decreased CP susceptibility varied markedly with the different serotypes, which prevalences differed notably in site and in time.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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