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Updated: Dec 9, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Mupirocin and Chlorhexidine Genotypic Resistance Found in Staphylococcus aureus Isolated From Young Infants Below 90
Hyun Mi Kang1, Ki Cheol Park2, Joonhong Park3
1From the Division of Infectious Diseases, Departments of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Objectives:
To investigate the genetic characteristics associated with eradication failure of Staphylococcus aureus in infants below 90 days old.
Methods:
S. aureus isolated from clinical specimen cultures (blood, surgical tissue, or drainage, pus, etc.) and routine screening cultures in the neonatal intensive care unit (nasal and axillary skin swab) from patients below 90 days old were collected prospectively for 1 year, from August 2017 to July 2018. The isolates underwent typing and screening for genes associated with chlorhexidine (qacA/B), quaternary ammonium (smr), and mupirocin resistance (iles mutation, mupA, mupB), as well as Panton-Valentine leukocidin (PVL) toxin.
Results:
During the study period, 40 nonduplicate isolates were included for analyses, of which 70.0% were methicillin-resistant S. aureus (MRSA). Mupirocin resistance was found in 25% of the total isolates; 17.4% of the colonizers; and 35.3% of the pathogens (P = 0.196). Chlorhexidine resistance gene was found in 3 MRSA isolates colonized in the nares of preterm infants. All isolates harbored the disinfectant quaternary ammonium compound (QAC) resistance gene. PVL toxin gene was found in 57.5%, and the presence of PVL gene among colonizers and pathogens was similar (69.6% vs. 41.2%, P = 0.072).
Conclusions:
Mupirocin, chlorhexidine, and QAC-resistant MRSAs harboring the PVL toxin gene were found in the nasal carriages of preterm infants. In this highly vulnerable patient population, one-fourth of the isolates harbored mupirocin-resistant genes, and all were resistant to QAC disinfectants. These strains are associated with persistence in both carriage and environmental reservoirs within the hospitals.
Insights
Genetic analysis revealed that Staphylococcus aureus strains resistant to mupirocin, chlorhexidine, and quaternary ammonium compounds (QACs), often carrying the Panton-Valentine leukocidin (PVL) gene, are prevalent in preterm infants, contributing to persistent infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Genetics
Background:
- Staphylococcus aureus eradication failure in infants poses a significant clinical challenge.
- Neonatal intensive care units (NICUs) are susceptible environments for S. aureus colonization and transmission.
- Understanding the genetic basis of antimicrobial resistance in S. aureus is crucial for effective treatment strategies.
Purpose of the Study:
- To identify genetic factors contributing to Staphylococcus aureus eradication failure in infants under 90 days old.
- To characterize resistance genes and virulence factors in S. aureus isolates from a neonatal intensive care unit.
Main Methods:
- Prospective collection of S. aureus isolates from clinical and screening cultures in NICU patients (<90 days old) over one year.
- Genotyping of isolates for genes conferring resistance to chlorhexidine (qacA/B), quaternary ammonium compounds (smr), and mupirocin (iles, mupA, mupB).
- Screening for the Panton-Valentine leukocidin (PVL) toxin gene.
Main Results:
- Of 40 isolates, 70% were methicillin-resistant S. aureus (MRSA).
- Mupirocin resistance was observed in 25% of isolates (35.3% of pathogens).
- All isolates carried quaternary ammonium compound (QAC) resistance genes; 57.5% harbored the PVL gene.
Conclusions:
- Mupirocin, chlorhexidine, and QAC-resistant MRSA strains with PVL toxin genes were identified in nasal carriage of preterm infants.
- One-fourth of isolates from this vulnerable population showed mupirocin resistance, and all were QAC-resistant.
- These resistant S. aureus strains contribute to persistent colonization and environmental contamination in hospitals.
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