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Salmonella enterica serotype Virchow associated with human infections in Switzerland: 2004-2009.

Bonalli M, Stephan R, Käppeli U, Cernela N, Adank L, Hächler H - BMC Infect. Dis. (2011)

Bottom Line: We found a high prevalence (62%) of nalidixic acid resistant strains, suggesting an equally high rate of decreased fluoroqionolone susceptibility, whereas intermediate resistance to ciprofloxacin was negligible.Virchow.Nevertheless, the situation in Switzerland coincided with findings in other European countries.

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Affiliation: Institute for Food Safety and Hygiene, University of Zurich, Switzerland.

ABSTRACT

Background: Salmonellosis is one of the most important foodborne diseases and a major threat to public health. Salmonella serotype Virchow ranks among the top five serovars in Europe.

Method: A total of 153 strains isolated from different patients from 2004 through 2009 in Switzerland were further characterized by (i) assessing phenotypic antibiotic resistance profiles using the disk diffusion method and (ii) by genotyping using pulsed-field gel electrophoresis (PFGE) after macrorestriction with XbaI in order to evaluate strain relationship.

Results: The relative frequency of S. Virchow among other Salmonella serovars varied between 4th to 8th rank. The annual incidence ranged from 0.45/100'000 in 2004 to 0.40/100'000 in 2009. A total of 48 strains (32%) were resistant to one to 3 antimicrobials, 54 strains (36%) displayed resistance patterns to more than three antibiotics. No trend was identifiable over the years 2004 to 2009. We found a high prevalence (62%) of nalidixic acid resistant strains, suggesting an equally high rate of decreased fluoroqionolone susceptibility, whereas intermediate resistance to ciprofloxacin was negligible. Two strains were extended spectrum β-lactamase (ESBL) producers. Analysis of PFGE patterns uncovered a predominant cluster (similarity coefficient above 80%) consisting of 104 of the 153 strains.

Conclusion: The worldwide increase of antibiotic resistances in Salmonella is an emerging public health problem. For Switzerland, no clear trend is identifiable over the years 2004 to 2009 for S. Virchow. Antimicrobial susceptibility and resistance profiles varied considerably within this period. Nevertheless, the situation in Switzerland coincided with findings in other European countries. Genotyping results of this strain collection revealed no evidence for an undetected outbreak within this time period.

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Resistance of S. Virchow strains isolated over the years 2004 trough 2009 in Switzerland. Each box shows the percentage fraction of the resistant, intermediate and susceptible sub-population over time for one antimicrobial. Values significantly (p < 0.05) deviating from average are marked with * (more resistant) or + (less resistant), respectively.
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Figure 2: Resistance of S. Virchow strains isolated over the years 2004 trough 2009 in Switzerland. Each box shows the percentage fraction of the resistant, intermediate and susceptible sub-population over time for one antimicrobial. Values significantly (p < 0.05) deviating from average are marked with * (more resistant) or + (less resistant), respectively.

Mentions: We found 62% of all S. Virchow strains resistant to nalidixic acid, while 98% were susceptible to ciprofloxacin, and only 2% (3 isolates) were intermediate according to CLSI criteria [15]. As many as 49% of the isolates were resistant to sulfamethoxazole, 41% to trimethoprim and 36% to tetracycline. All strains were susceptible to cefotaxime, and only 1.3% were resistant to amoxicillin/clavulanic acid. During the years 2004 to 2007 the resistance situation remained consistent. In 2008, for several antimicrobials the percentage of resistant strains was significantly higher (p < 0.05) than in the preceding years. Interestingly, multiple percentages during 2009 lay beneath the average values of the years 2004 to 2009 (p < 0.05) (Figure 2). Hence, there were no significant trends in resistance development observable for any antibiotic.


Salmonella enterica serotype Virchow associated with human infections in Switzerland: 2004-2009.

Bonalli M, Stephan R, Käppeli U, Cernela N, Adank L, Hächler H - BMC Infect. Dis. (2011)

Resistance of S. Virchow strains isolated over the years 2004 trough 2009 in Switzerland. Each box shows the percentage fraction of the resistant, intermediate and susceptible sub-population over time for one antimicrobial. Values significantly (p < 0.05) deviating from average are marked with * (more resistant) or + (less resistant), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3050727&req=5

Figure 2: Resistance of S. Virchow strains isolated over the years 2004 trough 2009 in Switzerland. Each box shows the percentage fraction of the resistant, intermediate and susceptible sub-population over time for one antimicrobial. Values significantly (p < 0.05) deviating from average are marked with * (more resistant) or + (less resistant), respectively.
Mentions: We found 62% of all S. Virchow strains resistant to nalidixic acid, while 98% were susceptible to ciprofloxacin, and only 2% (3 isolates) were intermediate according to CLSI criteria [15]. As many as 49% of the isolates were resistant to sulfamethoxazole, 41% to trimethoprim and 36% to tetracycline. All strains were susceptible to cefotaxime, and only 1.3% were resistant to amoxicillin/clavulanic acid. During the years 2004 to 2007 the resistance situation remained consistent. In 2008, for several antimicrobials the percentage of resistant strains was significantly higher (p < 0.05) than in the preceding years. Interestingly, multiple percentages during 2009 lay beneath the average values of the years 2004 to 2009 (p < 0.05) (Figure 2). Hence, there were no significant trends in resistance development observable for any antibiotic.

Bottom Line: We found a high prevalence (62%) of nalidixic acid resistant strains, suggesting an equally high rate of decreased fluoroqionolone susceptibility, whereas intermediate resistance to ciprofloxacin was negligible.Virchow.Nevertheless, the situation in Switzerland coincided with findings in other European countries.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Food Safety and Hygiene, University of Zurich, Switzerland.

ABSTRACT

Background: Salmonellosis is one of the most important foodborne diseases and a major threat to public health. Salmonella serotype Virchow ranks among the top five serovars in Europe.

Method: A total of 153 strains isolated from different patients from 2004 through 2009 in Switzerland were further characterized by (i) assessing phenotypic antibiotic resistance profiles using the disk diffusion method and (ii) by genotyping using pulsed-field gel electrophoresis (PFGE) after macrorestriction with XbaI in order to evaluate strain relationship.

Results: The relative frequency of S. Virchow among other Salmonella serovars varied between 4th to 8th rank. The annual incidence ranged from 0.45/100'000 in 2004 to 0.40/100'000 in 2009. A total of 48 strains (32%) were resistant to one to 3 antimicrobials, 54 strains (36%) displayed resistance patterns to more than three antibiotics. No trend was identifiable over the years 2004 to 2009. We found a high prevalence (62%) of nalidixic acid resistant strains, suggesting an equally high rate of decreased fluoroqionolone susceptibility, whereas intermediate resistance to ciprofloxacin was negligible. Two strains were extended spectrum β-lactamase (ESBL) producers. Analysis of PFGE patterns uncovered a predominant cluster (similarity coefficient above 80%) consisting of 104 of the 153 strains.

Conclusion: The worldwide increase of antibiotic resistances in Salmonella is an emerging public health problem. For Switzerland, no clear trend is identifiable over the years 2004 to 2009 for S. Virchow. Antimicrobial susceptibility and resistance profiles varied considerably within this period. Nevertheless, the situation in Switzerland coincided with findings in other European countries. Genotyping results of this strain collection revealed no evidence for an undetected outbreak within this time period.

Show MeSH
Related in: MedlinePlus