ABSTRACT
INTRODUCTION: Staphylococcal colonization is a risk factor for healthcare-associated infections, which are frequent in Neonatal Intensive Care Units (NICU). This study analyzed microbiology, epidemiology and clinical aspects of Staphylococcus spp. colonizing neonates. METHODOLOGY: Nasal or periumbilical swabs were evaluated from 175 newborns admitted to a NICU of a Rio de Janeiro hospital from March to September 2009. Clinical data were obtained from the medical records. SCCmec typing and the mecA and Panton-Valentine Leukocidin (PVL) genes were detected by PCR. Clonal diversity was evaluated by pulsed-field gel electrophoresis. RESULTS: Staphylococcus spp. isolates were detected in 98 (56%) neonates, 66.3% of them had birth weight ≤ 2500 g, 62.2% were preterm (Ë 37 weeks) and the mean length of hospitalization was 14.9 days. Among the 133 isolates identified, 48.1% were S. epidermidis, 23.3% S. haemolyticus and 13.5% S. aureus. Methicillin-resistant Staphylococcus isolate was detected in 77.6% of neonates. The methicillin-resistant S. aureus isolates carried the SCCmec type IV, while 94.6% of S. epidermidis and 85.7% of S. haemolyticus presented non-typeable cassettes. Among the S. aureus, 55.6% had PVL genes and the USA800 genotype was prevalent. Two genotypes of S. epidermidis and one of S. haemolyticus clustered 42.2% and 25.8% of the isolates, respectively. S haemolyticus colonization was associated with the use of parenteral nutrition and mechanical ventilation. CONCLUSION: High rate of neonates colonized by methicillin-resistant Staphylococcus species and the permanence of clones circulating in the NICU highlight the importance for continuous and preventive surveillance in this high-risk population.
Subject(s)
Methicillin-Resistant Staphylococcus aureus/genetics , Staphylococcal Infections/microbiology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Brazil/epidemiology , Cross Infection/drug therapy , Cross Infection/epidemiology , Cross Infection/microbiology , Electrophoresis, Gel, Pulsed-Field , Female , Humans , Infant, Newborn , Intensive Care Units, Neonatal , Male , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Polymerase Chain Reaction , Staphylococcal Infections/drug therapy , Staphylococcal Infections/epidemiologyABSTRACT
BACKGROUND: Staphylococcus epidermidis is an opportunistic pathogen involved in hospital-acquired infections, particularly in those related to medical devices. This study characterized 50 genetically unrelated S. epidermidis isolates from bloodstream infections (BSIs, n = 31) and nares (n = 19) of neonates in relation to staphylococcal chromosomal cassette mec (SCCmec) type, biofilm production and associated genes, and the arginine catabolic mobile elements (ACME), in order to detect virulence factors that could discriminate a potential invasiveness isolate or predict an increasing pathogenicity. RESULTS: Isolates from both groups showed no difference for biofilm production and ACME genes detection. However, BSI isolates harbored more frequently the sdrF and sesI genes (p < 0.05), whereas biofilm producer isolates were associated with presence of the aap gene. The sdrF gene was also significantly more in the biofilm producer isolates from BSI. The SCCmec type IV and the ccr2 complex were related to BSI isolates (p < 0.05), while 83% of the nasal isolates were non-typeable for the SCCmec elements, with the mec complex and ccr undetectable as the most frequent profile. CONCLUSIONS: Despite the great clonal diversity displayed by S. epidermidis isolates from neonates, BSI isolates harbored more frequently the sdrF and sesI adhesin genes, while nasal isolates were very variable in SCCmec composition. These aspects could be advantageous to improve colonization in the host increasing its pathogenicity.
Subject(s)
Methicillin Resistance/genetics , Nasal Cavity/microbiology , Staphylococcal Infections/microbiology , Staphylococcus epidermidis/genetics , Staphylococcus epidermidis/isolation & purification , Staphylococcus epidermidis/pathogenicity , Virulence/genetics , Adhesins, Bacterial/genetics , Arginine/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/isolation & purification , Biofilms/growth & development , Brazil/epidemiology , DNA, Bacterial/genetics , Genetic Variation , Humans , Infant, Newborn , Multilocus Sequence Typing , Phenotype , Polymerase Chain Reaction , Staphylococcal Infections/blood , Staphylococcal Infections/epidemiology , Staphylococcus epidermidis/drug effects , Virulence Factors/geneticsABSTRACT
To characterize 46 methicillin-resistant coagulase-negative staphylococci from Brazilian neonates, we investigated their SCCmec type, susceptibility and clonality. Staphylococcus epidermidis and Staphylococcus haemolyticus were the prevalent species. SCCmec types III or IV were detected in 53.3% S. epidermidis, whereas 63.6% S. haemolyticus were nontypeable. Despite the diversity, specific clones carried specific SCCmec elements, highlighting that effective typing can help in epidemiological analysis.
