Emergence of community-associated methicillin-resistant Staphylococcus aureus  strains in the neonatal intensive care unit: an infection prevention and patient safety challenge

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) infections cause significant morbidity and mortality in neonatal intensive care units (NICUs). We characterized the clinical and molecular epidemiology of MRSA strains colonizing NICU patients. Nasal MRSA isolates (n=250, from 96 NICU patients) recovered through active surveillance from 2009-2014 were characterized with Staphylococcal cassette chromosome mec (SCCmec) typing and detection of mupA (marker of high-level mupirocin resistance) and qacA/B (marker associated with chlorhexidine resistance). Factors associated with community-associated (CA-) or healthcare-associated (HA-) MRSA were evaluated. The overall prevalence of MRSA nasal colonization was 3.9%. Of 96 neonates in our retrospective cohort, 60 (63%) were colonized with CA-MRSA strains and 35 (36%) were colonized with HA-MRSA strains. Patients colonized with HA-MRSA were more likely to develop MRSA infections than patients colonized with CA-MRSA (13/35 [37%] vs. 8/60 [13%], p=0.007), although the interval from colonization to infection was shorter in CA-MRSA-colonized infants (0 days [range −1 to 4] versus HA-MRSA-colonized infants, 7 days [−1 to 43], p=0.005). Maternal peripartum antibiotics were associated with CA-MRSA colonization (adjusted odds ratio [aOR] 8.7; 95% confidence interval [CI] 1.7, 45.0); intubation and surgical procedures were associated with HA-MRSA colonization (aOR 7.8; 95% CI 1.3, 47.6 and aOR 6.0; 95% CI 1.4, 24.4, respectively). Mupirocin- and chlorhexidine-resistant MRSA was isolated from 4 and 8 patients, respectively; carriage of a mupirocin-resistant strain precluded decolonization. CA-MRSA strains are prominent in the NICU and associated with distinct risk factors. Given community reservoirs for MRSA acquisition and transmission, novel infection prevention strategies are needed.

Impact of Health Care Exposure on Genotypic Antiseptic Tolerance in Staphylococcus aureus Infections in a Pediatric Population

“…Previous studies of children have shown an association between antiseptic tolerance genes in S. aureus and the presence of central venous lines (CVLs), as well as a higher rate of invasive infection (18). Many previous pediatric studies, however, have been biased by including high-risk populations, such as neonates/infants and oncology and cardiac surgery patients (12,18,20,21).…”

New Threats from an Old Foe: Methicillin-Resistant <b><i>Staphylococcus aureus</i></b> Infections in Neonates

“…Approximately 1 out of 5 neonates colonized with MRSA may develop an infection [5, 6, 18, 19], corresponding to a relative risk of 24.2 (95% CI 8.9–66.0) compared to noncolonized neonates [16]. The median time between MRSA colonization and the onset of infection may range from 4 to 9 days [18, 20].…”

“…The incidence of MRSA infections in neonates with a BW ≤1,000 g has been reported to be 53.4 per 10,000 infants, compared to 23.2, 7.9, and 5.0 per 10,000 infants in the BW categories of 1,001–1,500, 1,501–2,500, and > 2,500 g, respectively [2]. Other risk factors for MRSA infections include prolonged hospitalization, overcrowding and understaffing in neonatal wards, long-term use of respiratory support, intravascular catheters, antibiotics, and total parenteral nutrition, as well as surgical procedures [6, 18, 19]. The clinical manifestation of MRSA infections may range from mild focal infections, such as conjunctivitis and skin and soft tissue infections, to more severe forms like toxic shock syndrome [24] and even invasive infections such as sepsis, necrotizing pneumonia, meningitis, endocarditis, osteomyelitis, liver abscesses, and urinary tract infections [2, 18, 23, 25-27].…”

“…The median time between MRSA colonization and the onset of infection may range from 4 to 9 days [18, 20]. Prematurity has been identified to be the principal risk factor for MRSA colonization and subsequent infections [2, 17, 19, 23].…”

“…Other risk factors for MRSA infections include prolonged hospitalization, overcrowding and understaffing in neonatal wards, long-term use of respiratory support, intravascular catheters, antibiotics, and total parenteral nutrition, as well as surgical procedures [6, 18, 19]. The clinical manifestation of MRSA infections may range from mild focal infections, such as conjunctivitis and skin and soft tissue infections, to more severe forms like toxic shock syndrome [24] and even invasive infections such as sepsis, necrotizing pneumonia, meningitis, endocarditis, osteomyelitis, liver abscesses, and urinary tract infections [2, 18, 23, 25-27]. Sepsis, especially late-onset sepsis, is currently the most common manifestation of invasive MRSA infections, with one third of cases presenting as MRSA sepsis [2, 25].…”