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Contamination of expressed human breast milk with an epidemic multiresistant Staphylococcus aureus clone
F R Novak1, A V DA Silva1, A N Hagler1
1*Universidade Federal do Rio de Janeiro, Instituto de Microbiologia Prof. Paulo de Góes, CCS, Bl I, Cidade Universitária, Rio de Janeiro, RJ and †Instituto Fernandes Figueira, Banco de Leite Humano, Av. Rui Barbosa, 716, Flamengo, Rio de Janeiro, RJ, Brazil.
Abstract:
Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major cause of outbreaks in intensive care units. Infants make up a sector of the population that presents a high risk for MRSA infections. Mother-to-infant transmission has been indicated as a possible cause of MRSA infections in neonates. The occurrence and characteristics of MRSA in samples of banked human milk were investigated by selective culture, antibiogram and pulsed-field gel electrophoresis. MRSA contamination was found in 11% of 500 samples of expressed, fresh-frozen milk from 500 different donors at five Brazilian milk banks. The great majority of the contaminated samples passed breast milk quality control criteria for dispensing as raw milk under Brazilian and American guidelines. Most of the MRSA isolates belonged to the Brazilian epidemic clone, which is reported to be widespread in several Brazilian states, in Argentina and in Portugal. It is concluded that expressed breast milk can be a reservoir of multiresistant S. aureus epidemic clones. Studies are necessary to assess the source of contamination and potential role of MRSA-contaminated milk in the transmission of MRSA to neonates.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) was found in 11% of banked human milk samples. This contamination, often undetected by quality controls, highlights a potential reservoir for MRSA transmission to infants.
Area of Science:
- Microbiology
- Infectious Diseases
- Neonatal Health
Background:
- Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a significant concern in intensive care units.
- Infants are a high-risk population for MRSA infections, with mother-to-infant transmission being a suspected route.
- The presence and characteristics of MRSA in banked human milk require investigation to understand transmission dynamics.
Purpose of the Study:
- To investigate the occurrence and characteristics of MRSA in banked human milk samples.
- To determine if MRSA-contaminated milk meets existing quality control standards.
- To identify the prevalent MRSA clones in milk samples.
Main Methods:
- Selective culture and antibiogram were used to detect MRSA.
- Pulsed-field gel electrophoresis (PFGE) was employed for molecular typing of MRSA isolates.
- Analysis of 500 expressed, fresh-frozen human milk samples from five Brazilian milk banks.
Main Results:
- MRSA contamination was detected in 11% of the 500 human milk samples analyzed.
- The majority of contaminated samples met Brazilian and American guidelines for raw milk dispensing.
- Most MRSA isolates belonged to the widespread Brazilian epidemic clone, also found in Argentina and Portugal.
Conclusions:
- Expressed human milk can serve as a reservoir for epidemic clones of multiresistant Staphylococcus aureus.
- Further studies are needed to identify the sources of milk contamination.
- The potential role of MRSA-contaminated milk in neonatal MRSA transmission requires assessment.