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Epidemiology of colonization and microbial infection in Neonatal Intensive Care Unit: clinical and molecular approach

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Thaís Alves Barbosa
Total Authors: 1
Document type: Master's Dissertation
Press: Botucatu. 2016-03-22.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Medicina. Botucatu
Defense date:
Advisor: Maria de Lourdes Ribeiro de Souza da Cunha; Maria Regina Bentlin

The need to stay in the Neonatal Intensive Care Unit (NICU) represents one of the main factors of colonization and infection. It is known that, soon after birth, bacterial colonization of the newborn starts from contact with maternal microbiota, health professionals, or from environmental exposure. Newborns (NBs) who remain in intensive care have a greater predisposition to infection after the colonization. The longer survival and prolonged hospitalization of NBs have led to an increase in infection rates, especially in NICUs. Objectives: To study the epidemiology of colonization and microbial infection in a cohort of neonates admitted to a NICU with a clinical and molecular approach. Methodology: All neonates born in the University Hospital of Botucatu Medical School admitted to the NICU for one year were included in the study. Tracheal aspirate samples were collected, as well as samples of the nasal and anal sites by using sterile swabs. The NBs were followed up until the final outcome – ICU discharge or death. Isolated mircroorganisms were submitted to identification and were tested for antimicrobial drug susceptibility in order to determine the minimum inhibitory concentration (MIC) by the E-test. The type of staphylococcal cassette chromosome mec (SCCmec) was determined among the methicillin-resistant Staphylococcus spp. For the research on prevalent clones in the unit, the characterization of clusters was performed by pulsed-field gel electrophoresis (PFGE). Results: The results showed higher incidence of infection (27.8%) and colonization by Staphylococcus epidermidis mainly in the nasal mucosa (56.4%). The colonization by Serratia marcescens was predominant in the anal mucosa (26.8%). The results showed S. epidermidis resistant to trimethoprim-sulfamethoxazole, and S. epidermidis and Enterococcus faecalis resistant to quinopristin-dalfopristin. From the 402 samples of Staphylococcus spp. studied, 204 (50.7%) had the mecA gene, more frequently isolated from the nasal mucosa. There were 47 isolates harboring SCCmec type I, 12 carrying SCCmec type II, 77 carrying SCCmec type III, and 43 harboring SCCmec type IV. Molecular typing to determine the clusters by the PFGE technique demonstrated the presence of isolates of different NBs with either identical or high similarity profiles, which suggests cross-contamination. In addition, isolates from the same NB but of different sites also presented as identical, proving that the microorganism that colonized the NB at the time of collection was also the infectious agent. The statistical analysis revealed that the colonization process can be considered a risk factor for infection with a three times greater risk compared to non-colonized NBs. Among the risk factors for colonization, the use of parenteral nutrition and peripherally-inserted central catheter (PICC) increased the risk six times and four times, respectively. Conclusion: The findings of this study can assist in the appropriate antimicrobial choice as the colonization process occurs after the birth and the empirical therapy is often required. Knowing the microbiological profile of the unit allows to create proper antimicrobial protocols for preventing and treating healthcare-associated infections (HCAIs) aiming to improve the quality of the care provided. To this end, the implementation of surveillance cultures which help the HCAI control commission as well as the care team to develop the measures to be adopted is very important. (AU)

Grantee:Thaís Alves Barbosa
Support Opportunities: Scholarships in Brazil - Master