ABSTRACT
OBJECTIVE: To evaluate clonal dissemination of methicillin-resistant coagulase-negative staphylococci (CNS). SETTING: Neonatal intensive care unit of a 180-bed, university-affiliated general hospital. PATIENTS: Neonates admitted to the neonatal intensive care unit between March 1999 and October 2000, from whom CNS were isolated as a unique pathogen. Patients from other wards from whom epidemiologically unrelated staphylococci strains were obtained served as control-patients. METHODS: Conventional methods were used for phenotypic characterization of CNS. Methicillin resistance was determined by mecA polymerase chain reaction (PCR) amplification. Genotypic characterization was done by random amplification of DNA with degenerated primers (RAPD) and repetitive element sequence-based PCR (rep-PCR). RESULTS: Forty methicillin-resistant CNS isolates obtained from neonates were characterized as Staphylococcus epidermidis (33), S. hominis (5), S. warneri (1), and S. auricularis (1). Both RAPD and rep-PCR indicated the presence of 4 different clones among the 33 S. epidermidis isolates. In turn, the 4 randomly selected, epidemiologically unrelated methicillin-resistant CNS strains obtained from control-patients showed 3 new profiles by RAPD and 2 by rep-PCR, which differed from the corresponding patterns mentioned earlier. Persistence of S. hominis in a neonate could be assessed by both genotypic techniques. CONCLUSIONS: The molecular characterization of the methicillin-resistant CNS studied indicated dissemination of one particular methicillin-resistant CNS clone among the neonates in the ward studied. Although RAPD showed a superior power to discriminate among methicillin-resistant CNS isolates, both RAPD and rep-PCR detected intraspecific and interspecific genomic diversity.
Subject(s)
Bacterial Typing Techniques/methods , Methicillin Resistance/genetics , Polymerase Chain Reaction/methods , Random Amplified Polymorphic DNA Technique , Staphylococcus/classification , Argentina/epidemiology , Case-Control Studies , Cross Infection/epidemiology , Cross Infection/microbiology , Humans , Infant, Newborn , Intensive Care Units, Neonatal , Staphylococcal Infections/epidemiology , Staphylococcal Infections/microbiology , Staphylococcus/geneticsABSTRACT
OBJETIVOS. Los neonatos constituyen una población de alto riesgo para infecciones por estafilococos coagulasa negativa (ECN). Para comprender mejor dichos procesos se enfocó su estudio desde el punto de vista de la relación huésped-parásito. Para ello se propuso establecer si hay concordancia entre el resultado esperado de dicha relación dada por el índice de riesgo de los neonatos y el índice de virulencia de los microorganismos y la calificación de cepa colonizante o infectante, que surge del diagnóstico médico realizado en base a criterios clínicos. MÉTODOS. Se estudiaron 24 neonatos en los cuales se realizó un seguimiento epidemiológico estableciendo como factores de riesgo para infecciones por estos microorganismos: presencia de catéteres, sondas vesicales, cirugía previa, ingreso de más de 72 horas en el hospital, tratamiento prolongado con antibióticos y condiciones de inmunosupresión. En las cepas de ECN recuperadas de los materiales clínicos se determinaron los siguientes factores de patogenicidad: sinergismo de hemólisis, producción de polisacárido extracelular (slime), adherencia a catéter de teflon e hidrofobicidad. RESULTADOS. Hubo coincidencia entre el diagnóstico clínico y el resultado esperado de la relación húesped-parásito en 21 pacientes (87,5 por ciento). En 8 de estos pacientes no se produjo infección a pesar de presentar las cepas 3 de 4 factores de virulencia, ya que los pacientes no presentaban suficientes factores de riesgo. CONCLUSIONES. El estudio de la microbiología solamente en términos de identificación y tratamiento de los organismos causantes de enfermedad distorsiona el contexto biológico. Es necesario comprender la relación huésped-parásito para un enfoque adecuado del estudio de los procesos infecciosos (AU)
Subject(s)
Infant, Newborn , Humans , Staphylococcal Infections , Staphylococcus , Risk Factors , Virulence , Bacterial Adhesion , Coagulase , Host-Parasite InteractionsABSTRACT
Streptococcus agalactiae (GBS) is a leading cause of serious neonatal infection. In this study we determine the prevalence, serotype distribution and genomic diversity of GBS in vagina of pregnant women.Vaginal swabs of 531 pregnant women were cultured on Columbia Agar Base Blood, GBS Agar Base and Todd Hewitt Broth. GBS were characterized by group and type-specific agglutination. Genomic polymorphism was studied by random amplification of DNA (RAPD). Seventeen patients (3.2 percent) were positive for GBS, resulting serotype III the most frequent. RAPD detected 16 different RAPD profiles from 21 GBS studied, revealing a good discriminatory power. In this sense, this method showed different genotype from GBS serotype III recovered from successive samples of two patients, suggesting reinfection. In conclusion, the combination of RAPD and serotyping appear promising for epidemiological studies. Finally, findings of reinfection after therapy during pregnancy, led us to suggest performing prenatal GBS screening and intrapartum prophylaxis in order to reduce neonatal risk.
Subject(s)
Humans , Female , Pregnancy , Adult , Infant, Newborn , Pregnancy Complications, Infectious/diagnosis , Streptococcal Infections/diagnosis , Streptococcus agalactiae/genetics , Phenotype , Pregnancy Complications, Infectious/microbiology , Pregnancy Trimester, Third , Random Amplified Polymorphic DNA Technique , Streptococcal Infections/microbiology , Streptococcus agalactiae/isolation & purificationABSTRACT
Streptococcus agalactiae (GBS) is a leading cause of serious neonatal infection. In this study we determine the prevalence, serotype distribution and genomic diversity of GBS in vagina of pregnant women.Vaginal swabs of 531 pregnant women were cultured on Columbia Agar Base Blood, GBS Agar Base and Todd Hewitt Broth. GBS were characterized by group and type-specific agglutination. Genomic polymorphism was studied by random amplification of DNA (RAPD). Seventeen patients (3.2 percent) were positive for GBS, resulting serotype III the most frequent. RAPD detected 16 different RAPD profiles from 21 GBS studied, revealing a good discriminatory power. In this sense, this method showed different genotype from GBS serotype III recovered from successive samples of two patients, suggesting reinfection. In conclusion, the combination of RAPD and serotyping appear promising for epidemiological studies. Finally, findings of reinfection after therapy during pregnancy, led us to suggest performing prenatal GBS screening and intrapartum prophylaxis in order to reduce neonatal risk. (Au)
Subject(s)
Humans , Female , Pregnancy , Adult , Infant, Newborn , Streptococcal Infections/diagnosis , Streptococcus agalactiae/genetics , Pregnancy Complications, Infectious/diagnosis , Phenotype , Pregnancy Trimester, Third , Random Amplified Polymorphic DNA Technique , Streptococcal Infections/microbiology , Streptococcus agalactiae/isolation & purification , Pregnancy Complications, Infectious/microbiologyABSTRACT
Epidemioiogicai studies of Streptococcus agalactiae strains have been limited by the lack of sensitive and discriminatory methods for comparing clinical isolates. Serotyping, albeit a widely used methodology, has been shown to possess low capability to distinguish between epidemiologically related and unrelated isolates. We have employed here a random amplification of polymorphic DNA (RAPD) assay, using degenerate oligonucleotides as primers, to characterize S. agalactiae isolates from related or unrelated clinical samples. Epidemioiogically-related isolates (mother-infant pairs) showed identical profiles by this methodology. On the contrary, 12 epidemioiogically-unrelated isolates (ciassified into 5 different serotypes) resulted in ll distinct RAPD patterns. This suggests that the proposed modified RAPD assay provides a highly discriminatory tool for the analysis of genomic diversity among isolates from pathogenic organisms.
Subject(s)
Humans , Female , Pregnancy , Infant, Newborn , Random Amplified Polymorphic DNA Technique , Streptococcus agalactiae/isolation & purification , DNA Primers , Genome, Bacterial , Polymerase Chain Reaction , Serotyping , Streptococcus agalactiae/classification , Streptococcus agalactiae/geneticsABSTRACT
Epidemioiogicai studies of Streptococcus agalactiae strains have been limited by the lack of sensitive and discriminatory methods for comparing clinical isolates. Serotyping, albeit a widely used methodology, has been shown to possess low capability to distinguish between epidemiologically related and unrelated isolates. We have employed here a random amplification of polymorphic DNA (RAPD) assay, using degenerate oligonucleotides as primers, to characterize S. agalactiae isolates from related or unrelated clinical samples. Epidemioiogically-related isolates (mother-infant pairs) showed identical profiles by this methodology. On the contrary, 12 epidemioiogically-unrelated isolates (ciassified into 5 different serotypes) resulted in ll distinct RAPD patterns. This suggests that the proposed modified RAPD assay provides a highly discriminatory tool for the analysis of genomic diversity among isolates from pathogenic organisms.(AU)
