Genomic analysis of virulence factors and antimicrobial resistance of group B Streptococcus isolated from pregnant women in northeastern Mexico.

INTRODUCTION: Group B Streptococcus (GBS) causes infections in women during pregnancy and puerperium and invasive infections in newborns. The genes lmb, cylE, scpB, and hvgA are involved with increased virulence of GBS, and hypervirulent clones have been identified in different regions. In addition, increasing resistance of GBS to macrolides and lincosamides has been reported, so knowing the patterns of antibiotic resistance may be necessary to prevent and treat GBS infections. This study aimed to identify virulence genes and antibiotic resistance associated with GBS colonization in pregnant women from northeastern Mexico. METHODS: Pregnant women with 35-37 weeks of gestation underwent recto-vaginal swabbing. One swab was inoculated into Todd-Hewitt broth supplemented with gentamicin and nalidixic acid, a second swab was inoculated into LIM enrichment broth, and a third swab was submerged into a transport medium. All samples were subcultured onto blood agar. After overnight incubation, suggestive colonies with or without hemolysis were analyzed to confirm GBS identification by Gram staining, catalase test, hippurate hydrolysis, CAMP test, and incubation in a chromogenic medium. We used latex agglutination to confirm and serotype GBS isolates. Antibiotic resistance patterns were assessed by Vitek 2 and disk diffusion. Periumbilical, rectal and nasopharyngeal swabs were collected from some newborns of colonized mothers. All colonized women and their newborns were followed up for three months to assess the development of disease attributable to GBS. Draft genomes of all GBS isolates were obtained by whole-genome sequencing. In addition, bioinformatic analysis to identify genes encoding capsular polysaccharides and virulence factors was performed using BRIG, while antibiotic resistance genes were identified using the CARD database. RESULTS: We found 17 GBS colonized women out of 1154 pregnant women (1.47%). None of the six newborns sampled were colonized, and no complications due to GBS were detected in pregnant women or newborns. Three isolates were serotype I, 5 serotype II, 3 serotype III, 4 serotype IV, and 2 serotype V. Ten distinct virulence gene profiles were identified, being scpB, lmb, fbsA, acp, PI-1, PI-2a, cylE the most common (3/14, 21%). The virulence genes identified were scpB, lmb, cylE, PI-1, fbsA, PI-2a, acp, fbsB, PI-2b, and hvgA. We identified resistance to tetracycline in 65% (11/17) of the isolates, intermediate susceptibility to clindamycin in 41% (7/17), and reduced susceptibility to ampicillin in 23.5% (4/17). The tetM gene associated to tetracyclines resistance was found in 79% (11/14) and the mel and mefA genes associated to macrolides resistance in 7% (1/14). CONCLUSIONS: The low prevalence of colonization and the non-occurrence of mother-to-child transmission suggest that the intentional search for GBS colonization in this population is not justified. Our results also suggest that risk factors should guide the use of intrapartum antibiotic prophylaxis. The detection of strains with genes coding virulence factors means that clones with pathogenic potential circulates in this region. On the other hand, the identification of decreased susceptibility to antibiotics from different antimicrobial categories shows the importance of adequately knowing the resistance patterns to prevent and to treat GBS perinatal infection.

[Group B streptococcal perinatal infection: A Global, Latin American and Mexican Overview]. / Infección perinatal por estreptococo del grupo B: panorama global, en América Latina y en México.

Group B streptococci (Streptococcus agalactiae) cause a number of infections in women during pregnancy and postpartum, such as urinary tract infection, chorioamnionitis and endometritis, consequently may affect the newborn. Group B streptococci is the most common cause of severe infections in newborns in developed countries. Studies on the epidemiology of group B streptococci infections in Latin America are still limited. This information is also unknown in Mexico, but studies carried out in the center of the country have found high rates of vaginal colonization in pregnant women and there are case series and case reports of newborns. Microbiological and molecular epidemiology studies in Mexico have shown that populations of group B streptococci have a clonal distribution and that there are clones with genetic and phenotypic characteristics of high virulence that appear to be responsible for most of perinatal pathology. However, the actual role of group B streptococci in perinatal pathology in Mexico is unknown. Consequently, whether to perform or not the screening for determining the group B streptococci colonization status in pregnant women, and the indication or not for intrapartum antibiotic prophylaxis to prevent neonatal group B streptococci infection in Mexico, are still controversial.

[Prolonged exposure to antibiotics and the risk of late-onset sepsis (LOS) in neonates of 1,000-1,500 g: a cohort study]. / Exposición prolongada a antibióticos y riesgo de sepsis tardía (ST) en neonatos de 1,000 a <1,500 g: estudio de cohorte.

OBJECTIVE: To determine whether prolonged exposure to antibiotics (>5 days) increases the risk of late-onset sepsis (LOS) in newborns of 1,000-1,500 g. METHODS: A cohort study in newborns with suspected perinatal infection, with a survival greater than seven days. The exposed cohort was composed of newborns with antibiotic therapy initiated at first postnatal day, lasting >5 days, with negative blood cultures before the fifth day of life, and without clinical evidence of sepsis. The non-exposed cohort was identical but with antibiotics stopped before the fifth day of life. Patients were followed daily for clinical and laboratory evidence of LOS. Others risk factors for LOS were analyzed. STATISTICAL ANALYSIS: We analyzed the incidence, the relative risk (RR) with 95% CI. To measure the time to occurrence of an event of LOS after exposure, Kaplan-Meier survival curve and log-rank test were used. RESULTS: We followed up 49 patients in each group. The incidence was 33.6%. The time of follow-up was 839 vs. 1,291 person-days. Prolonged exposure to antibiotics was associated with a higher risk of LOS (RR: 21.1; 95% CI: 6.5-68.9; p=0.000). The late-onset sepsis-free time was 17.1±1.1 vs. 26.3±0.8 days. CONCLUSIONS: The risk of LOS was higher in newborns with prolonged exposure to antibiotics and increased with the days of exposure.

[Colonization by Candida in a neonatal intensive care unit]. / Colonización por Candida en una unidad de cuidados intensivos neonatales.

BACKGROUND: Candida infections have increased in the last few decades. Previous colonization is the most important risk factor for the development of fungemia. Understanding local epidemiology is necessary in order to select the optimal anti-fungal treatment. The purpose of this study was to establish colonization by Candida in patients, staff and medical devices in a neonatal intensive care unit. METHODS: A prospective cohort study was conducted. Cultures were obtained from different anatomic sites, from medical devices and from the hands of healthcare staff at admission and every 7 days until discharge of the unit. Identification and susceptibility tests to amphotericin B, fluconazole, itraconazole, voriconazole and caspofungin were performed. RESULTS: Out of 98 patients, 24 % were already colonized at admission, 15 % became colonized during their stay at the hospital. Out of 738 samples obtained from devices, 2 % were positive. Out of 89 cultures obtained from hands, 55 % were positive. A total of 124 Candida strains were retrieved; Candida parapsilosis was the most common species (59 %), followed by Candida albicans (26 %). Resistance to itraconazole was only found in 13 %. CONCLUSIONS: Colonization in neonatal intensive care-admitted patients was 40 %, and it was a common event in the hands of the healthcare staff. Candida parapsilosis was the predominant species. Resistance was found only to itraconazole.

INTRODUCCIÓN: las infecciones por Candida se han incrementado en las últimas décadas. La colonización previa es el principal factor de riesgo para el desarrollo de fungemia. Es necesario conocer la epidemiología local de un hospital para seleccionar el tratamiento óptimo. El objetivo del estudio que se presenta fue establecer la colonización por especies de Candida en pacientes, personal y dispositivos médicos en una unidad de cuidados intensivos neonatales. MÉTODOS: se llevó a cabo un estudio prospectivo de cohorte. Se obtuvieron muestras de diferentes sitios anatómicos, de dispositivos médicos y de manos del personal de salud, al ingreso de los pacientes y cada siete días hasta el egreso de la unidad. Se realizó identificación de los microorganismos y se determinó su sensibilidad a anfotericina B, fluconazol, itraconazol, voriconazol y caspofungina. RESULTADOS: de 98 pacientes, 24 % estaba colonizado al ingreso y 15 % se colonizó durante su estancia en la unidad. De 738 muestras de dispositivos, 2 % resultó positivo. De 89 cultivos de manos, 55 % fue positivo. Se recuperaron en total 124 cepas de Candida; la especie parapsilosis fue la especie más común (59 %), seguida de albicans (26 %). Solo se encontró resistencia a itraconazol en 13 %. CONCLUSIONES: se observó colonización en 40 % de los pacientes ingresados en la unidad de cuidados intensivos neonatales y en las manos del personal de salud fue frecuente. Predominó la especie Candida parapsilosis. Solo se encontró resistencia a itraconazol.