Antimicrobial resistance and virulence determinants in coagulase-negative staphylococci isolated mainly from preterm neonates

Coagulase-negative staphylococci (CoNS) are the most common isolates from blood culture in neonates resulting in high mortality and morbidity. This study investigated CoNS obtained from blood cultures of neonates for antibiotic resistance and virulence factors, and possible association with inflammatory response (C-reactive protein). A total of 93 CoNS isolates were collected from 76 blood cultures of neonates at the Maternity hospital in Kuwait in a six-month period and investigated for susceptibility to antibiotics, carriage of staphylococcal cassette chromosomemec(SCCmec), and virulence-associated genes. The 93 CoNS isolates consisted ofS.epidermidis(76; 81.7%),S.capitis(12; 12.9%),S.hominis(2; 2.1%),S.warneri(2; 2.1%) andS.haemolyticus(1; 1.0%). Eighty-six (92.4%) of the isolates were resistant to cefoxitin (MR-CoNS) while 49 (52.7%) expressed multi-antibiotic resistance. The methicillin-resistant isolates (MR-CoNS) carried SCCmecIII, SCCmecIVa and four combinations of SCCmectypes including SCCmectypes I+IVa (oneS.warneriand 25S.epidermidisisolates), types I+III (oneS.epidermidisisolate), types III+IVa (sixS.epidermidisisolates) and types I+III+IVa (oneS.epidermidisisolate). The most common virulence-related genes wereicaC,seb,arcdetected in 69.7%, 60.5%, 40.8% of the isolates respectively. Two isolates were positive fortst1. No association between C-reactive protein and antibiotic resistance or virulence factors was established. This study revealed thatS.epidermidiscarrying different SCCmecgenetic elements, was the dominant CoNS species isolated from neonatal blood cultures with 90.3% and 36.6% of the isolates positive for genes for biofilm and ACME production respectively.