The patient was a gardener living on a farm that raised livestock and thus came into contact with cows, suggesting a possible con- tamination of the patient from an animal origin. The patient was initially treated with cloxacillin, gentamicin and metronidazole for only 3 days and then switched to vancomycin, gentamicin and fosfomycin. After 2 weeks of this intravenous treatment, he was prescribed oral ofloxacin and rifampicin for 8 weeks. A CT scan of the chest 23 days after the initial hospitalization showed a marked decrease in the retrosternal collection and the patient’s parotitis, and the infection was considered cured at the end of treatment. One year later, in February 2012, the patient was sampled at home to detect the possible persistence of mecC-MRSA carriage. Two different methicillin-susceptible S. aureus strains were isolated from nose and throat swabs. mecC PCR was negative, and the genetic backgrounds of the two isolates differed from that of strain LIM84 on the basis of agr typing and DNA microarray results. This demonstrated the absence of long-term colonization with the mecC-positive strain. This case illustrates the ongoing evolution of bacteria, requiring microbiologists to investigate atypical results of antibiotic suscep- tibility tests. It also shows that conventional phenotypic tests are still useful for detecting new or atypical resistance mechanisms, which cannot be detected by genotypic methods. This challenges the view that genotypic methods are now the gold standard for re- sistance studies of S. aureus. As mecC detection is crucial for optimal patient management, this capability should be added to commercial diagnostic tools. Acknowledgements This case report was presented at the Fifty-second Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, CA, USA, 2012 (slide session 197: Resistance in Staphylococcus aureus, reference: C1-1739). We thank Dr Jean-Claude Vignon (general practitioner) for his contribution to this work. Funding This work was supported bygrants from Institut National de la Sante ´ et de la Recherche Me ´ dicale (Inserm). Transparency declarations None to declare. Author contributions O. B. isolated the strain and wrote the report, F. L. and M. B. were responsible for genotypic analyses, B. F. and P. V. managed the patient and F. L. and M.-C. P. reviewed the report. References 1 Fluit AC. Livestock-associated Staphylococcus aureus. Clin Microbiol Infect 2012; 18: 735 – 44. 2 Fang H, Hedin G. Rapid screening and identification of methicillin-resistant Staphylococcus aureus from clinical samples by selective-broth and real-time PCR assay. J Clin Microbiol 2003; 41: 2894 – 9. 3 Ito T, Hiramatsu K, Tomasz A et al. Guidelines for reporting novel mecA gene homologues. Antimicrob Agents Chemother 2012; 56: 4997 – 9. 4 Garcia-Alvarez L, Holden MT, Lindsay H et al. Meticillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study. Lancet Infect Dis 2011; 11: 595 – 603. 5 Shore AC, Deasy EC, Slickers P et al. Detection of staphylococcal cassette chromosome mec type XI carrying highly divergent mecA, mecI, mecR1, blaZ, and ccr genes in human clinical isolates of clonal complex 130 methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2011; 55: 3765 – 73. 6 Paterson GK, Larsen AR, Robb A et al. The newly described mecA homologue, mecA LGA251 , is present in methicillin-resistant Staphylococcus aureus isolates from a diverse range of host species. J Antimicrob Chemother 2012; 67: 2809 – 13. 7 Eriksson J, Espinosa-Gongora C, Stamphoj I et al. Carriage frequency, diversity and methicillin resistance of Staphylococcus aureus in Danish small ruminants. Vet Microbiol 2013; 163: 110 – 5. 8 Medhus A, Slettemeas JS, Marstein L et al. Methicillin-resistant Staphylococcus aureus with the novel mecC gene variant isolated from a cat suffering from chronic conjunctivitis. J Antimicrob Chemother 2013; 68: 968 – 9. 9 Laurent F, Chardon H, Haenni M et al. MRSA harboring mecA variant gene mecC, France. Emerg Infect Dis 2012; 18: 1465 – 7. 10 Stegger M, Andersen PS, Kearns A et al. Rapid detection, differentiation and typing of methicillin-resistant Staphylococcus aureus harbouring either mecA or the new mecA homologue mecA LGA251 . Clin Microbiol Infect 2012; 18: 395 – 400. 11 Harrison EM, Paterson GK, Holden MT et al. Whole genome sequencing identifies zoonotic transmission of MRSA isolates with the novel mecA homologue mecC. EMBO Mol Med 2013; 5: 509 – 15. J Antimicrob Chemother 2013 doi:10.1093/jac/dkt258 Advance Access publication 25 June 2013 The bla CTX-M-1 IncI1/ST3 plasmid is dominant in chickens and pets in Tunisia Raoudha Grami 1,2 , Wejdene Mansour 2 , Safia Dahmen 1 , Wahib Mehri 3 , Marisa Haenni 1 , Mahjoub Aouni 2 and Jean-Yves Madec 1 * 1 Unite ´ Antibiore ´ sistance et Virulence Bacte ´ riennes, ANSES Site de Lyon, 31 avenue Tony Garnier, 69364 Lyon, France; 2 Laboratoire des Maladies Transmissibles et Substances Biologiquement Actives, Faculte ´ de Pharmacie, Monastir, Tunisie; 3 Centre Re ´gional des Recherches Ve ´te ´rinaires de Sousse, Tunisie *Corresponding author. Tel: +33-4-78-72-65-43; Fax: +33-4-78-61-91-45; E-mail: jean-yves@anses.fr Keywords: antimicrobial resistance, ESBLs, CTX-M, veterinary, plasmids Research letters 2950 Downloaded from https://academic.oup.com/jac/article/68/12/2950/696106 by guest on 21 June 2022