Mohammad Aghazadeh, Reza Ghotaslou, Mohammad Ahangarzadeh Rezaee, Mohammad Hassan Moshafi, Zoya Hojabri, Fereshteh Saffari

Tabriz, Iran

Author Affiliations: Tabriz Research Center of Infectious and Tropical Diseases, Tabriz University of Medical Sciences, Tabriz, Iran (Aghazadeh M, Ghotaslou R, Ahangarzadeh Rezaee M, Saffari F); Department of Pharmaceutical Science, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran (Moshafi MH); Department of Microbiology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran (Hojabri Z)

Corresponding Author: Fereshteh Saffari, Tabriz Research Center of Infectious and Tropical Diseases, Tabriz University of Medical Sciences, Tabriz, Iran (Tel: + 98 411 3364661; Fax: + 98 411 3364661; Email: fereshtesaffari@yahoo.com)

doi: 10.1007/s12519-014-0524-7

Online First November 2014.

Background: Currently, coagulase negative staphylococci (CoNS) have got much attention as a serious health problem especially in neonates and children. High incidence of antibiotic resistance, in particular methicillin resistance, has complicated the treatment of these organisms. The aim of this study is to determine the susceptibility to different antimicrobial agents and the prevalence of macrolides­lincosamides-streptogramins B (MLSB) resistance in CoNS isolates obtained from pediatric patients.

Methods: Totally 157 CoNS isolates from various clinical samples were examined for antibiotic resistance using disk diffusion and E-test methods. Double-disk test was applied to detect constitutive and inducible MLSB resistance (cMLSB and iMLSB) phenotypes.

Results: Resistance to methicillin was seen in 98 (62.4%) isolates. All isolates were susceptible to vancomycin and linezolid. The prevalence of resistance to antibiotics tested was as follows: fusidic acid (n=58, 36.9%), gentamicin (n=73, 46.5%), ciprofloxacin (n=81, 51.6%), clindamycin (n=112, 71.3%), erythromycin (n=129, 82.2%) and trimethoprim/sulfamethoxazole (n=133, 84.7%). iMLSB phenotype was seen in 14 (8.9%) isolates, and 18 (11.5%) and 98 (62.4%) isolates showed MS and cMLSB phenotypes, respectively. We observed that high overall antibiotic resistance rates were associated significantly with methicillin resistance. Conversely, iMLSB phenotype was correlated neither with methicillin resistance nor with invasiveness.

Conclusion: Given the similarity observed between the prevalence of iMLSB and MS phenotypes, the performance of disk diffusion induction test is strongly recommended in our region.

                                                                                                  World J Pediatr 2015;11(3):250-254

Key words: antibiotic susceptibility; coagulase negative staphylococci; inducible resistance; pediatrics