16 S rRNA-based molecular identification of coagulase-negative Staphylococcus species in neonates with sepsis and their antibiotic resistance patterns in Ahvaz, Iran.

Abstract

Introduction: Coagulase-negative staphylococci (CoNS) are among the leading causes of neonatal sepsis (NS). NS can be divided into two types: early-onset sepsis (EOS), which usually occurs less than 72 h after birth, and late-onset sepsis (LOS), which can occur 8 to 28 days after birth. According to newly published statistics, the incidence rates of EOS and LOS in neonates are 0.5-3.1% and 2-32%, respectively. This study aimed to determine the prevalence of common CoNS isolates and their antibiotic resistance patterns in NS cases in Ahvaz, Iran.

Methods: This cross-sectional study (October 2022-April 2023) was conducted on all neonates (0-28 days old) with NS manifestations admitted to Imam Khomeini Hospital. Blood culture samples were collected and incubated at 37 °C for 24 h. The bacterial isolates were identified via standard biochemical tests, and the Staphylococcus epidermidis strains were identified via polymerase chain reaction (PCR) of the SesC gene. The other suspected CoNS species were identified using 16 S rRNA sequencing.

Results: In total, 1221 blood culture bottles were collected from 1330 neonates with NS manifestations. A total of 111 (9.1%) blood cultures were positive for bacterial growth. Overall, 51 staphylococcal isolates, including 39 (76.5%) CoNS species and 12 (23.5%) S. aureus isolates, were identified. Using SesC gene PCR and 16 S rRNA sequencing, the CoNS species were as follows: 28 (71.8%) S. epidermidis, 5 (12.8%) S. hominis, 4 (10.38%) S. haemolyticus and 2 (5.1%) S. warneri. In total, the frequency of NS caused by CoNS isolates was 35.1% (n = 39/111). All CoNS isolates were methicillin resistant and presented the highest antibiotic resistance rates (100.0%) to cefoxitin, ampicillin, erythromycin, and linezolid.

Conclusions: This study revealed a high incidence of methicillin-resistant coagulase-negative staphylococci (MRCoNS) with high antibiotic resistance rates in NS patients from Ahvaz. To prevent the spread of these isolates in healthcare systems, measures such as monitoring the optimal use of antibiotics on the basis of the results of laboratory antibiograms seem necessary.