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MRSA infection in the neonatal intensive care unit Expert Rev. Anti Infect. Ther. 11(5), 499–509 (2013)
Mario Giuffrè, Celestino Bonura, Domenico Cipolla and Caterina Mammina* Dipartimento di Scienze per la Promozione della Salute e MaternoInfantile ‘G. D’Alessandro’, Università degli Studi di Palermo, Via del Vespro 133, 90127 Palermo, Italy *Author for correspondence: Tel.: +39 091 655 3623 Fax: +39 091 655 3641
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Methicillin-resistant Staphylococcus aureus (MRSA) is well known as one of the most frequent etiological agents of healthcare-associated infections. The epidemiology of MRSA is evolving with emergence of community-associated MRSA, the clonal spread of some successful clones, their spillover into healthcare settings and acquisition of antibacterial drug resistances. Neonatal intensive care unit (NICU) patients are at an especially high risk of acquiring colonization and infection by MRSA. Epidemiology of MRSA in NICU can be very complex because outbreaks can overlap endemic circulation and make it difficult to trace transmission routes. Moreover, increasing prevalence of community-associated MRSA can jeopardize epidemiological investigation, screening and effectiveness of control policies. Surveillance, prevention and control strategies and clinical management have been widely studied and are still the subject of scientific debate. More data are needed to determine the most cost-effective approach to MRSA control in NICU in light of the local epidemiology. KEYWORDS:#! -23!sEPIDEMIOLOGYs(! -23!sINFECTIONCONTROLsMOLECULARTYPINGs-23!s.)#5 sSURVEILLANCE
Neonatal intensive care units (NICUs) provide care for high-risk infants, including preterm and seriously ill full-term newborns and infants with congenital birth defects. The need for prolonged stay, along with the large use of invasive life support measures, increase the opportunity for acquisition of late-onset healthcare-associated infections (HAIs). Methicillin-resistant Staphylococcus aureus (MRSA) is among the most common type of pathogen in the healthcare system and the community. NICU patients may be particularly susceptible to colonization, infection and severe complications caused by this organism. This review attempts to analyze the complex interaction between a unique high-risk setting, such as NICUs, and the evolving epidemiological and ecological features of MRSA. Peculiar characteristics of NICUs compared with other healthcare settings & adult intensive care units
HAIs are an important problem in NICU, where environmental and host factors often contribute to higher rates of infection than pediatric and adult intensive care units (ICUs) [1,2] . In addition to nosocomial environment and devices, other factors, such as prenatal history and maternal colonization, have to be www.expert-reviews.com
10.1586/ERI.13.28
considered when evaluating the specific profile of an NICU patient [3,4] . Moreover, neonates with major or severe malformation are a very high-risk group, because of complexity in their care and theirfrequent need for early surgery [5] . Neonates hospitalized in NICUs represent a highly vulnerable patient population; they are frequently preterm with low birth weight, chronic diseases and intrinsic immunologic immaturity, which is more profound in premature infants of 24–30 weeks gestational age. They are particularly exposed to high risk of infection because of their low level passively acquired antibodies, diminished functional capacity of many components of the immune system, thinness and poor keratinization of skin, frequent colonization of mucous membranes and skin with microorganisms endemic in NICUs, exposure to antibiotics, invasive procedures and frequent contacts with healthcare workers (HCWs) [2,3] . Neonatal sepsis in the developed world has an estimated prevalence of 1–4 per 1000 live births, whereas in the developing world the rate is higher, between 6.5 and 38 per 1000 live hospital births [6] . HAIs are still the major source of morbidity and mortality in NICUs. The increasing survival rates of premature infants in the past 25 years has been followed by increased rates of infection within this patient category. For very
© 2013 Expert Reviews Ltd
ISSN 1478-7210
499
Review
Giuffrè, Bonura, Cipolla & Mammina
low birth weight (VLBW) infants, nosocomial sepsis has been reported in 21–43% of cases [2,6,7] . This prevalence is inversely related to gestational age and birth weight, and is directly related to severity of illness, length of stay, ventilation, central catheters and parenteral nutrition days. Intravenous lipids, steroids, acid inhibitors and broad-spectrum antibiotics have proved to be further exposures at risk [2,6,7] . Over 60% of infections in NICUs are caused by Gram-positive organisms (S. aureus, Enterococcus spp. and coagulase-negative staphylococci) [2,6,7] . However, acute symptoms, such as shock, sudden clinical deterioration and fulminant sepsis, are more often associated with infection by Gram-negative organisms [2,6,7] . Fungal sepsis frequently occurs in extremely low birth weight (ELBW;
