Non-Multidrug-Resistant, MRSA in a Neonatal Unit
Non-Multidrug-Resistant, MRSA in a Neonatal Unit
Background: In the last decade, non-multiresistant methicillin-resistant Staphylococcus aureus (NM-MRSA) has been described as an important agent in bloodstream infections in our hospital.
Methods: This prospective cohort study, conducted from February 2009 through January 2010 in the neonatal unit, evaluated 403 newborns (NB), their 382 mothers and 148 health care workers (HCW).
Results: Approximately 217 NB (54%), 187 mothers (48%) and 87 HCW (59%) were colonized by S. aureus (SA). MRSA colonization was greater among NB (15%) than mothers (4.7%) and HCW (3.4%). Although mother-to-NB transmission occurred, in most cases mothers were not responsible for NB colonization. There were 2 predominant PFGE patterns among the NB and some mothers and HCW became colonized by them. Factors significantly associated with MRSA carriage by NB were lower level of maternal schooling (risk factor: odds ratio: 2.99; 95% confidence interval: 1.10–8.07) and maternal rhinosinusitis (protective factor: odds ratio: 0.33; 95% confidence interval:0.12–0.88). Among NB who remained hospitalized for more than 72 hours, breast feeding was protective (odds ratio: 0.22; 95% confidence interval: 0.05–0.98). All the isolates were NM-MRSA, carried few virulence factors and SCCmec types IVa and type IVd predominated.
Conclusions: Although there were no cases of infection, nosocomial transmission of MRSA clearly occurred in the neonatal unit, and this highlights the need for infection control practices such as hand hygiene to prevent cross-dissemination. Other healthcare practices, which are very basic but also ample in scope, may play a role, such as general education of women and breast feeding.
Staphylococcus aureus is one of the most important human bacterial pathogens causing nosocomial and community infections. Despite being mostly nosocomial for decades, methicillin-resistant S. aureus (MRSA)—commonly called healthcare-associated methicillin-resistant S. aureus (HA-MRSA) because of its origin—became also an important cause of community-acquired infections. Community-acquired methicillin-resistant S. aureus (CA-MRSA) was characterized with phenotypic and genotypic traits substantially different from HA-MRSA, such as a non-multidrug-resistant susceptibility pattern and carriage of staphylococcal cassette chromosomemec types IV or V. Isolates of CA-MRSA, however, were also described in hospitals to which they may have migrated from the community, and in this setting, they were more appropriately designated non-multidrug-resistant, methicillin-resistant S. aureus (NM-MRSA).
In our hospital in the neonatal unit, although infection by MRSA is very rare, the incidence of colonization and its source are unknown. The source could be the community because of colonization of the mothers and healthcare workers or the source might be cross-transmission within the hospital. The aims of this study were to evaluate the colonization of newborns (NB) by methicillin-resistant S. aureus(MRSA) and to determine the factors associated with this colonization. Antimicrobial susceptibility, virulence factors and clonality of isolates were also evaluated.
Abstract and Introduction
Abstract
Background: In the last decade, non-multiresistant methicillin-resistant Staphylococcus aureus (NM-MRSA) has been described as an important agent in bloodstream infections in our hospital.
Methods: This prospective cohort study, conducted from February 2009 through January 2010 in the neonatal unit, evaluated 403 newborns (NB), their 382 mothers and 148 health care workers (HCW).
Results: Approximately 217 NB (54%), 187 mothers (48%) and 87 HCW (59%) were colonized by S. aureus (SA). MRSA colonization was greater among NB (15%) than mothers (4.7%) and HCW (3.4%). Although mother-to-NB transmission occurred, in most cases mothers were not responsible for NB colonization. There were 2 predominant PFGE patterns among the NB and some mothers and HCW became colonized by them. Factors significantly associated with MRSA carriage by NB were lower level of maternal schooling (risk factor: odds ratio: 2.99; 95% confidence interval: 1.10–8.07) and maternal rhinosinusitis (protective factor: odds ratio: 0.33; 95% confidence interval:0.12–0.88). Among NB who remained hospitalized for more than 72 hours, breast feeding was protective (odds ratio: 0.22; 95% confidence interval: 0.05–0.98). All the isolates were NM-MRSA, carried few virulence factors and SCCmec types IVa and type IVd predominated.
Conclusions: Although there were no cases of infection, nosocomial transmission of MRSA clearly occurred in the neonatal unit, and this highlights the need for infection control practices such as hand hygiene to prevent cross-dissemination. Other healthcare practices, which are very basic but also ample in scope, may play a role, such as general education of women and breast feeding.
Introduction
Staphylococcus aureus is one of the most important human bacterial pathogens causing nosocomial and community infections. Despite being mostly nosocomial for decades, methicillin-resistant S. aureus (MRSA)—commonly called healthcare-associated methicillin-resistant S. aureus (HA-MRSA) because of its origin—became also an important cause of community-acquired infections. Community-acquired methicillin-resistant S. aureus (CA-MRSA) was characterized with phenotypic and genotypic traits substantially different from HA-MRSA, such as a non-multidrug-resistant susceptibility pattern and carriage of staphylococcal cassette chromosomemec types IV or V. Isolates of CA-MRSA, however, were also described in hospitals to which they may have migrated from the community, and in this setting, they were more appropriately designated non-multidrug-resistant, methicillin-resistant S. aureus (NM-MRSA).
In our hospital in the neonatal unit, although infection by MRSA is very rare, the incidence of colonization and its source are unknown. The source could be the community because of colonization of the mothers and healthcare workers or the source might be cross-transmission within the hospital. The aims of this study were to evaluate the colonization of newborns (NB) by methicillin-resistant S. aureus(MRSA) and to determine the factors associated with this colonization. Antimicrobial susceptibility, virulence factors and clonality of isolates were also evaluated.
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