Methicillin and vancomycin resistance in coagulase-negative Staphylococci isolated from the nostrils of hospitalized patients

Abstract

Introduction: Nasal colonization by coagulase-negative Staphylococci (CoNS) play an important role in nosocomial infections. This study aims to determine antibiotics susceptibility pattern and molecular screening of methicillin- and vancomycin-resistant nasal CoNS among hospitalized patients. Methodology: Nasal swabs were collected from 202 inpatients at Prince Hamzah Hospital, Jordan. Swabs were processed according to standard microbiological procedures to isolate Staphylococci. Antibiotic susceptibility testing was performed using disk diffusion, E-test, microdilution, and Vitek 2. Molecular analysis was performed using PCR for the detection of mecA, vanA, and vanB genes. Results: Nasal Staphylococci was isolated in 64/202 (31.7%) samples. Thirty isolates (14.8%) were CoNS, including S. haemolyticus (n = 17, 8.4%), S. sciuri (n = 6, 3%), S. epidermidis (n = 2, 1%), S. warneri (n = 2, 1%), S. hominis (n = 2, 1%), and S. lentus (n = 1, 0.5%). Twenty-two (10.9%) isolates were MR-CoNS harboring mecA gene. CoNS and MR-CoNS isolates were highly resistant to benzylpenicillin, erythromycin, fosfomycin, and imipenem. All isolates were sensitive to vancomycin by E-test and microdilution test and were negative for vanA and vanB genes. Nasal CoNS colonization was associated with an increased number of family members living with the participant (P = 0.04) and with admission to the orthopedic department (P = 0.03), while MR-CoNS colonization was associated with smoking (P = 0.03). Conclusions: Nasal colonization by unusual CoNS species and mecA-positive MR-CoNS are common among hospitalized patients. Absence of vanA and vanB genes suggests little contribution of nasal CoNS to vancomycin resistance transmission.