Prevalence, Antimicrobial Resistance, and Molecular Characteristics of Coagulase-Negative Staphylococci Isolated from Children’s Blood Cultures in Northeastern Iran Within 2013 - 2019

Coagulase-negative staphylococci (CoNS) are rolled in severe infections in animals and nosocomial infections in humans. Given that staphylococci other than Staphylococcus aureus are often reported only as CoNS in medical diagnosis laboratories, this study aimed to determine the exact species of this type of staphylococci in clinical samples.

This study also aimed to evaluate antibiotic resistance, the ability to carry cfr, qacA/B, mecA, and vanA genes, and the diversity of staphylococcal cassette chromosome mec (SCCmec) elements in mecA-carrying isolates.

Staphylococcus spp. strains were isolated from the blood samples of children admitted to Imam Reza Hospital in Bojnurd, Northeastern Iran, between 2013 - 2019. All CoNS isolates were evaluated for resistance to vancomycin and oxacillin using agar screening and other routine anti-CoNS antibiotics using the Kirby-Bauer disk diffusion method, based on the latest Clinical and Laboratory Standards Institute guidelines. The CoNS strains were isolated based on conventional methods and polymerase chain reaction (PCR)-restriction fragment length polymorphism. The PCR was applied to determine the diversity of SCCmec elements in the CoNS isolates.

In this study, 203 isolates were confirmed as CoNS belonging to nine staphylococci spp. S. capitis and S. epidermidis were the top two common CoNS. Type III was the dominant SCCmec type in mecA+ isolates.

The findings of this study showed that CoNS isolated from blood cultures have a relatively high diversity and antibiotic resistance. Therefore, further attention should be paid to the isolation of these strains in laboratories, and they should not be easily considered as contamination.