title: A Low Prevalence of Inducible Macrolide, Lincosamide, and Streptogramin B Resistance Phenotype among Methicillin-SusceptibleStaphylococcus aureusIsolated from Malaysian Patients and Healthy Individuals.
abstract: BACKGROUND
  Antibiotic resistance amongStaphylococcus aureusis of great concern worldwide. This resistance is further complicated by the ability ofS. aureusto confer cross-resistance to other antibiotics due to the presence of resistance genes, such as erythromycin resistance methylase (erm) genes, which render the bacterium resistant to macrolide-lincosamide-streptogramin B (MLSB) antibiotics. Resistance to these antibiotics can lead to therapeutic failure, resulting in significant morbidity and mortality in patients withS. aureusinfections.
  
  
  OBJECTIVE
  This study was performed to examine the distribution of MLSB-resistant strains of methicillin-susceptibleS. aureus(MSSA), which were obtained from hospitalized patients and normal healthy individuals (carriers) using phenotypic methods, such as the double-disk diffusion (D-test) and the genotypic method by polymerase chain reaction (PCR).
  
  
  METHODS
  A total of 183 nonduplicative MSSA isolates obtained from hospitalized patients (133) and carriers (50) in our previous studies were randomly selected for the D-test. The guidelines of the Clinical and Laboratory Standards Institute (CLSI) were used for the interpretation of the results of this test. The detection ofermA,ermB,ermCandmsrAgenes by PCR was performed for isolates that had positive D-test results and that were resistant to erythromycin.
  
  
  RESULTS
  Of the 183 MSSA isolates, 97.2% and 98.4% were highly susceptible to erythromycin and clindamycin, respectively. MSLB resistance was detected in four isolates (2.2%). Of the 133 MSSA isolated from hospitalized patients, only 3.0% (4/133) and 2.3% (3/133) exhibited resistance to erythromycin and clindamycin, respectively. With regard to the MLSB resistance phenotypes, only 1.6% and 0.6% exhibited inducible MLSB (iMLSB) and MS phenotypes, respectively. TheermCgene was detected in all three iMLSB phenotypes, and themsrAgene was detected in the MS phenotype. Surprisingly, all MSSA isolates (100%) from carriers exhibited extremely high susceptibility to both antibiotics.
  
  
  CONCLUSIONS
  The prevalence rates of iMLSB MSSA isolates vary according to geographical locations and the local antibiotic policy. The low prevalence rate of iMLSB MSSA isolates could probably be related to the judicious use of antibiotics for treatingS. aureusinfections in our studied population. Nonetheless, continuous antibiotic surveillance is still necessary to control any emergence of resistance isolates so that targeted therapy and effective control can be implemented accordingly.
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Asma
authors.initials: A
authors.lastname: Mesbah Elkammoshi
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia; Faculty of Medicine, North Khorasan University of Medical Sciences, Bojnurd, IR Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Ghasemzadeh-Moghaddam
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Syafinaz
authors.initials: S
authors.lastname: Amin Nordin
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Niazlin
authors.initials: N
authors.lastname: Mohd Taib
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Suresh
authors.initials: S
authors.lastname: Kumar Subbiah
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Vasanthakumari
authors.initials: V
authors.lastname: Neela
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Medical Microbiology and Parasitology, Universit Putra Malaysia, Serdang, Selangor, Malaysia.
authors.forename: Rukman
authors.initials: R
authors.lastname: Awang Hamat
keywords: Clindamycin; Erythromycin; Methicillin; Resistance; Staphylococcus aureus