The epidemiology of methicillin-susceptible and methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit, 2000–2007

Abstract

Objective: To assess the epidemiology of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) infections in a neonatal intensive care unit (NICU).Study Design: A retrospective chart review was conducted from 2000-2007; demographic and clinical characteristics of infected infants and crude mortality were assessed.Results: During the study period, there were 123 infections caused by MSSA and 49 infections caused by MRSA. Although the types of infections caused by MSSA and MRSA were similar, infants with MRSA infections were younger at clinical presentation than infants with MSSA infections (P ¼ 0.03). The overall rate of S. aureus infections was approximately 15-30 per 1000 patient-admissions. The rate of bacteremia and skin and soft tissue infections remained stable over time. Among extremely low birth weight infants (birth weight <1000 g), 4.8 and 1.8% developed an infection caused by MSSA or MRSA, respectively. Infections occurred in a bimodal distribution of birth weight; 53% of infections occurred in extremely low birth weight infants and 27% occurred among term infants birth weight X2500 g, many of whom underwent surgical procedures.Conclusions: MSSA and MRSA remain significant pathogens in the NICU, particularly for extremely premature infants and term infants undergoing surgery. Further work should investigate infection control strategies that effectively target the highest risk groups and determine if vertical transmission of MRSA is responsible for the younger age at presentation of infection.

Trends in Methicillin-Resistant Staphylococcus aureus Anovaginal Colonization in Pregnant Women in 2005 versus 2009

“…The increasing prevalence of USA300 in pregnant women, coinciding with the increased incidence in the NICU and in newborn nurseries (6,18,35), suggests that MRSA may be vertically transmitted from mother to infant. We recently reported that infants admitted to the NICU who developed MRSA infections were younger at presentation than infants with MSSA infections (median age of 23 days versus 32 days, respectively; P ϭ 0.03), suggesting potential evidence of vertical transmission (7). Using a variety of methods in different populations, several authors have recently studied the risk of vertical transmission of MRSA, resulting in infant colonization, from mothers detected by prenatal anovaginal cultures (2) or by culture of the anterior nares and vagina during labor (19,28,30).…”

“…Vertical transmission from mothers to infants at delivery has also been proposed as a possible mechanism of acquisition of CA-MRSA (1,2,7,28). S. aureus has been reported to colonize the vagina in 4 to 22% of pregnant women (2,4,9,13,14).…”

Methicillin-Resistant Staphylococcus aureus and the Eye: Current Concepts and Management Strategies

“…Reports of MRSA ophthalmic infections are numerous in the literature. They are more commonly seen in patients in neonatal ICUs [61][62][63], in post-ocular surgical patients [64][65][66][67][68][69][70][71][72][73][74][75], among healthcare workers [76,77] after corneal refractive surgery [77][78][79][80][81][82][83][84], in hospitalized pediatric patients [85], and in patients with chronic medical disease, immuno-suppression, or immunodeficiency [70,86].…”

Methicillin-Resistant and Susceptible Staphylococcus aureus Bacteremia and Meningitis in Preterm Infants

“…Among preterm neonates, invasive staphylococcal infections result in substantial morbidity and mortality. 1,2 Very low birth weight (VLBW) infants have an increased risk of infection due to exposure to nosocomial pathogens during extended hospitalizations. Most publications highlighting the epidemiology of infections with methicillin-resistant S aureus (MRSA) and methicillin-sensitive S aureus (MSSA) among VLBW neonates have described clusters of infections attributed to nosocomial outbreaks.…”