Predominance of Staphylococcus aureus in Peripheral Intravenous Catheter Colonization in Neonates: SCCmec Distribution and Antimicrobial Resistance

Background/Objectives: Peripheral intravenous catheters (PIVCs) are frequently used in neonatal intensive care units (NICUs) and can become major conduits of nosocomial infections, often colonized with clinically important bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Molecular data on PIVC-associated S. aureus in Moroccan NICUs remain limited. This study aimed to characterize bacterial colonization of PIVCs and investigate the phenotypic and molecular characteristics of recovered S. aureus, with particular emphasis on MRSA and staphylococcal cassette chromosome mec (SCCmec) types. Methods: 402 PIVC tips collected from 225 neonates hospitalized in the NICU of Hassan II University Hospital between June 2024 and May 2025 were analyzed using the Brun–Buisson quantitative culture method. Bacterial identification and antimicrobial susceptibility testing were performed, and S. aureus isolates were further characterized by PCR for 16S rRNA, mecA, and Panton–Valentine leukocidin (PVL) genes. SCCmec typing was performed on mecA-positive MRSA isolates. Results: Seventy-nine PIVC tips (19.7%, 95% CI: 16.1–23.8%) met the colonization criteria (≥1000 CFU/mL). A total of 152 bacterial isolates were recovered; S. aureus was the predominant species (n = 89, 58.6%), of which 15 (16.9%) were confirmed as MRSA. All MRSA isolates were mecA-positive. SCCmec typing identified two types; 12 isolates predominated and harboured SCCmec type IV (n = 12, 80.0%), while SCCmec type III was detected in three isolates (20.0%). No isolate harbored PVL genes, and no inducible clindamycin resistance was detected. MRSA isolates showed markedly higher resistance to gentamicin, fusidic acid, erythromycin, rifampicin, and clindamycin compared with MSSA isolates. Conclusions: S. aureus was the predominant bacterium recovered from PIVCs in our study. The predominance of SCCmec type IV among MRSA isolates provides original molecular epidemiological data from a Moroccan neonatal setting and highlights the need for continued surveillance of PIVC-associated MRSA and its molecular characteristics.