Skip to main content

Antimicrobial resistance patterns and genotypes of Salmonella enterica serovar Hadar strains associated with human infections in Switzerland, 2005–2010

  • N. CERNELA (a1), M. NÜESCH-INDERBINEN (a1), H. HÄCHLER (a1) and R. STEPHAN (a1)

Salmonella Hadar ranks in the top ten serovars reported from humans in Switzerland. In this study, all 64 S. Hadar strains isolated from different patients from 2005 to 2010 in Switzerland were characterized by (i) assessing phenotypic antimicrobial resistance profiles using the disk diffusion method and (ii) by genotyping using pulsed-field gel electrophoresis (PFGE) in order to evaluate the relationship of the strains. The annual incidences varied between 0·32/100 000 in 2005 (highest incidence) and 0·065/100 000 in 2007 (lowest incidence). In total 71·8% of the isolates were resistant to nalidixic acid. Although 40·6% of the strains were resistant to the β-lactam antibiotic ampicillin, they remained susceptible to the third-generation cephalosporin cefotaxime. Genotyping revealed a primary cluster consisting of 42 strains, sharing a similarity of >92%, with a subcluster of 18 strains with indistinguishable patterns. Resistance profiles allowed further differentiation within this subcluster providing a link of two strains to an outbreak in Spain.

Corresponding author
* Author for correspondence: Professor R. Stephan, Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstr. 272, CH-8057 Zurich, Switzerland. (Email:
Hide All
1. Rabsch W, Tschape H, Baumler AJ. Non-typhoidal salmonellosis: emerging problems. Microbes and Infection 2001; 3: 237247.
2. Olsen SJ, et al. The changing epidemiology of salmonella: trends in serovars isolated from humans in the United States, 1987–1997. Journal of Infectious Disease 2001; 183: 753761.
3. Majowicz SE, et al. The global burden of nontyphoidal salmonella gastroenteritis. Clinical Infectious Disease 2010; 50: 882889.
4. Huehn S, et al. Virulotyping and antimicrobial resistance typing of Salmonella enterica serovars relevant to human health in Europe. Foodborne Pathogen and Diseases 2010; 7: 523535.
5. Anon. European Food Safety Authority (EFSA) ( Accessed 29 January 2013.
6. Fantasia M, et al. Conventional and molecular approaches to isolates of Salmonella Hadar from sporadic and epidemic cases. Journal of Applied Microbiology 1997; 82: 494498.
7. Di Giannatale E, et al. Investigation of an outbreak of Salmonella enterica subsp. enterica serovar Hadar food illness in the Abruzzi region of Italy. Veterinary Italian 2008; 44: 405427.
8. Lenglet A. Over 2000 cases so far in Salmonella Hadar outbreak in Spain associated with consumption of pre-cooked chicken, July–August, 2005. Eurosurveillance 2005; 11: 10(8).
9. Hohmann EL. Nontyphoidal salmonellosis. Clinial Infectious Disease 2001; 32: 263269.
10. Anon. World Health Organisation: tackling antibiotic resistance from a food safety perspective in Europe. Copenhagen, 2011.
11. Parry CM. Antimicrobial drug resistance in Salmonella enterica . Current Opinion in Infectious Diseases 2003; 16: 467472.
12. Bagger-Skjøt L, et al. Less frequent Salmonella serovars as a reservoir of antimicrobial resistance. Journal of Antimicrobial Chemotherapy 2007; 59: 814815.
13. Grimont PAD, Weill FX. Antigenic Formulae of the Salmonella Serovars, 9th edn. WHO Collaborating Center for Reference and Research on Salmonella, Institut Pasteur: Paris, 2007.
14. Anon. Swiss Federal Office for Public Health ( Accessed 29 January 2013.
15. CLSI. Clinical and Laboratory Standards Institute: Performance Standards for Antimicrobial Susceptibility Testing; Eighteenth Informational Supplement. CLSI document M100-S18 2008, Wayne, PA.
16. Hendriksen RS, et al. Global monitoring of salmonella serovar distribution from the World Health Organization global foodborne infections network country data bank: Results of quality assured laboratories from 2001 to 2007. Foodborne Pathogens and Diseases 2011; 8: 887900.
17. van den Bogaard AE, Stobberingh EE. Epidemiology of resistance to antibiotics. Links between animals and humans. International Journal of Antimicrobial Agents 2000; 14: 327335.
18. Threlfall EJ, et al. The emergence and spread of antibiotic resistance in food-borne bacteria. International Journal of Food Microbiology 2000; 62: 15.
19. O'Brien TF. The global epidemic nature of antimicrobial resistance and the need to monitor and manage it locally. Clinical Infectious Diseases 1997; 24: 28.
20. Threlfall EJ, et al. Antimicrobial drug resistance in isolates of Salmonella enterica from cases of salmonellosis in humans in Europe in 2000: results of international multi-centre surveillance. Eurosurveillance 2003; 8: 4145.
21. Hakanen A, et al. Detection of decreased fluoroquinolone susceptibility in salmonellas and validation of nalidixic acid screening test. Journal of Clinical Microbiology 1999; 37: 35723577.
22. Møller Aarestrup F, Wiuff C. Is it time to change fluoroquinolone breakpoints for Salmonella spp? Antimicrobial Agents Chemotherapy 2003; 47: 827829.
23. Crump JA, et al. Reevaluating fluoroquinolone breakpoints for Salmonella enterica serovar Typhi and for non-typhi salmonellae. Clinical Infectious Diseases 2003; 37: 7581.
24. Coque TM, Baquero F, Canton R. (2008) Increasing prevalence of ESBL-producing Enterobacteriaceae in Europe. Eurosurveillance 2008; 20: 13(47).
25. Hasman H, et al. Beta-lactamases among extended-spectrum beta-lactamase (ESBL)-resistant Salmonella from poultry, poultry products and human patients in The Netherlands. Journal of Antimicrobial Chemotherapy 2005; 56: 115121.
26. Yates C, Amyes S. Extended-spectrum beta-lactamases in non-typhoidal Salmonella spp. isolated in the UK are now a reality: why the late arrival? Journal of Antimicrobial Chemotherapy 2005; 56: 262264.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 3
Total number of PDF views: 7 *
Loading metrics...

Abstract views

Total abstract views: 69 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 19th November 2017. This data will be updated every 24 hours.