Portación nasal, antibiotipo y genotipo de cepas de Staphylococcus aureus aisladas en estudiantes de Medicina y de Enfermería Campus San Felipe, Universidad de Valparaíso, Chile, durante el año 2017 / Nasal carriage, antibiotype and genotype of isolated Staphylococcus aureus from Medicine and Nursing students of Campus San Felipe, University of Valparaiso, Chile, during 2017

INTRODUCCIÓN. Staphylococcus aureus es parte de la microbiota nasal en 20-30% de la población general, colonización que constituye un reservorio para su transmisión, lo que es preocupante en cepas resistentes a meticilina (SARM). OBJETIVO: Determinar la prevalencia de S. aureus en estudiantes de Medicina y Enfermería del Campus San Felipe y caracterizar sus aislamientos. MATERIAL Y MÉTODOS: El 2017 se midió la portación nasal a 225 estudiantes, a las cepas aisladas se le analizó su antibiotipo por difusión en agar, la relación clonal por electroforesis de campo pulsado y MLST. En SARM se determinó el cassette SCCmec y gen de la leucocidina de Panton-Valentine. RESULTADOS: 61 estudiantes portaron S. aureus (27,1%) incluyendo dos cepas SARM (0,9%). Staphylococcus aureus mostró resistencia a penicilina (75%), eritromicina (14%) y clindamicina (10%), cloranfenicol (1,6%) y levofloxacina, oxacilina, cefoxitina (3,3%). Se diferenciaron diecinueve pulsotipos y el secuenciotipo coincidió con complejos clonales descritos a nivel mundial en portadores de S. aureus: CC30, CC8, CC97, CC15, CC22 y CC1. Las dos cepas SARM correspondieron con los clones chileno/cordobés y USA100NY/J, ambas del CC5. CONCLUSIÓN: La portación nasal de S. aureus y SARM en los estudiantes coincidió con la portación en la población general y las cepas sensibles a meticilina mostraron diversidad clonal y alta susceptibilidad antimicrobiana, exceptuando a penicilina.

BACKGROUND: Staphylococcus aureus is part of the nasal microbiota in 20-30% of the population. This colonization is also a reservoir for its dissemination, which is worrying in the case of strains with resistance to methicillin (MRSA). AIM: To determine S. aureus nasal carriage in nursing and medical students of San Felipe Campus and characterize theirs isolates. METHODS: During 2017, nasal swabs were taken from 225 students and seeded in salt manitol agar. Antibiotypes were determined by agar diffusion and the genetic clonality was assessed by PFGE and MLST in isolated S. aureus. SCCmec cassette and Panton-Valentine leukocidin gene (pvl) presence were determined in the MRSA isolates. RESULTS: 61 students carried S. aureus (27.1%) including two MRSA strains (0.9%). S. aureus showed resistance to penicillin (75%), erythromycin (14%) and clindamycin (10%), chloramphenicol (1.6%) and levofloxacin, oxacillin, cefoxitin (3.3%). Nineteen PFGE-types were differentiated, and their sequence-types coincided with main clonal complexes described in S. aureus carriers from different places worldwide: CC30, CC8, CC97, CC15, CC22 and CC1. MRSA strains belonged to CC5 and they corresponded to the Chilean/Cordobes and USA100NY/J clones. CONCLUSION: Nasal carriage of S. aureus and MRSA in students, coincided with the general population and sensitive-methicillin strains showed clonal diversity and high antimicrobial susceptibility except for penicillin.

Caracterización de cepas clínicas y ambientales de Salmonella enterica subsp. enterica serovar Heidelberg aisladas en Chile / Characterization of Salmonella Heidelberg strains isolated in Chile

Background: Salmonella Heidelberg (S. Heidelberg) causes gastroenteritis and sometimes bacteremia and endocarditis. In other countries, this serovar has multidrug resistance including extended-spectrum β-lactamases (ESBLs) and AmpC (β-lactamases (AmpC), associated with the blaCMY-2 gene. In Chile, an outbreak by S. Heidelberg occurred in 2011, the phenotypic and genetic characteristics of Chilean strains are unknown. Aim: To determine the antimicrobial susceptibility, presence of plasmids and virulence factor genes in S. Heidelberg strains isolated in Chile over the period 2006-2011. Material and Methods: In sixty-one S. Heidelberg clinical and environmental strains collected by the Public Health Institute in Chile during 2006-2011, antimicrobial susceptibility, plasmids and virulence factor genes (invA, sifA, pefA, agfA, lpfA and, stkD) were studied. Results: S. Heidelberg had a high susceptibility to sulfamethoxazole-trimethoprim, gentamicin, ceftriaxone, ceftiofur, chloramphenicol, amoxicillin-clavulanic acid and ampicillin. However, 52% had decreased susceptibility to ciprofloxacin and 33% resistance to tetracycline. ESBLs were detected in three strains isolated from blood cultures, environment and human feces. The latter strain was positive for AmpC and blaCMY-2 gene. Fifty three of 61 strains showed one to seven plasmids of 0.8 to approximately 30 kb. Most plasmids were small with sizes between 0.8 and 2 kb. All isolates were positive for all genes except pefA. Conclusions: S. Heidelberg isolated from Chilean samples was susceptible to first-line antimicrobials, except tetracycline and ciprofloxacin. The emergence of strains with ESBLs and AmpC should be a warning. The strains were homogeneous for virulence genes, but heterogeneous in their plasmids.

Detección de genes de virulencia en cepas de Enterococcus faecalis susceptibles y resistentes a aminoglucósidos / Detection of virulence genes in aminoglycoside susceptible and resistant Enterococcus faecalis

Background: Enterococcus spp. is an important cause of nosocomial infections A number of virulence factors that may enhance its ability to colonize have been described. Enterococcus is capable of acquiring resistance genes, including high-level resistance (HLR) to aminoglycoside antibiotics. Aim: to investigate the prevalence of genes encoding virulence factors in aminoglycosides susceptible and resistant E. faecalis. Materials and Methods: A total of 80 E. faecalis isolates from clinical (n: 52) and poultry samples (n: 28) were included in this study. Bacterial identification was performed by biochemical tests and phenotypificationwas done using the Phene-PlateTM system. Susceptibility to different antimicrobial agents was determined by the agar dilution method. Virulence genes aceI, agg, gelE and efaA were detected by multiplex PCR. Results: All isolates were susceptible to vancomycin and ampicillin. HLR to gentamicin (13.5%) and streptomycin (9.6%) was detected only in clinical isolates. The phenotyping revealed a great diversity of PhP-types, but only one clone with 7 strains of similar characteristics was found. The efaA gen was detected in 100% of the isolates. aceI gene was present in 94.2% and 75%, agg gene in 73.1%, and 67.9%, and gelE gene in 57.5% and 28.6% of the clinical and chicken isolates, respectively. Only 6 strains with HLR to aminoglycosides, belonging to the same phenotype, had the aceI, agg, gelE and efaA genes. Conclusions: E. faecalis with virulence genes and HLR to aminoglycosides were isolated from clinical and chicken samples in Antofagasta. More studies will be necessary to establish an association.

Antecedentes: Enterococcus spp. es una causa importante de infecciones nosocomiales, tanto en Chile como internacional. Se han descrito una serie de factores de virulencia en este microorganismo, que pueden, por ejemplo, aumentar su habilidad para colonizar. Enterococcus tiene capacidad de adquirir genes de resistencia, entre ellos la resistencia de alto nivel (RAN) a los antimicrobianos aminoglucósidos. Objetivo: Investigar la prevalencia de genes de virulencia en cepas de E. faecalis susceptibles y resistentes a aminoglucósidos. Material y Métodos: Un total de 80 cepas de E. faecalis aisladas de muestras clínicas (n: 52) y pollos (n: 28) se incluyeron en este estudio. La identificación se hizo por pruebas bioquímicas y se tipificaron por el sistema Phene-PlateMR. La susceptibilidad a diferentes antimicrobianos fue realizada por test de dilución en agar. Los genes de virulencia aceI, agg, gelE y efaA fueron investigados por RPC múltiple. Resultados: Todas las cepas de E. faecalis fueron susceptibles a vancomicina y ampicilina. Un 13,5% de las cepas clínicas presentaron resistencia de alto nivel a gentamicina y 9,6% a estreptomicina. La tipificación reveló una gran diversidad de fenotipos, pero se encontró un clon con 7 cepas de características similares. El gen efaA estaba presente en 100% de las cepas, gen aceI en 94,2 y 75%, gen agg 73,1 y 67,9% y gen gelE 57,5 y 28,6% de las cepas clínicas y de pollos, respectivamente. Seis cepas con resistencia de alto nivel a aminoglucósidos, que pertenecían a un mismo fenotipo exhibieron los genes efaA, aceI, agg y gelE juntos. Conclusiones: Cepas de E. faecalis que albergan genes de virulencia y con resistencia de alto nivel a aminoglucósidos fueron aisladas de muestras clínicas y de pollos en Antofagasta. Se requieren mayores estudios para establecer una asociación entre estos factores.

Susceptibilidad antimicrobiana y bases genéticas de la resistencia de cepas de Enterococcus causantes de infecciones en Cuba / Antimicrobial susceptibility and genetic bases for resistance of infectioncausingEnterococcus strains in Cuba

Objective. To identify infection-causing Enterococcus species in Cuban hospitalsand determine their susceptibility to antimicrobial drugs, as well as their resistance mechanisms. Methods. A total of 687 Enterococcus isolates from 30 Cuban hospitals in nine provinces of the country were studied over the period 2000–2009. The species were identified using both the conventional method and the automatic API® system.The minimum inhibitory concentration was determined for 13 antimicrobial drugs following the standards recommended by the Clinical Laboratory and Standards Institute. The polymerase chain reaction technique was used to characterize the genes that were resistant to aminoglycosides, erythromycin, tetracycline, andglucopeptides. The presence of beta-lactamase was determined by the chromogenic cephalosporin test. Results. The most prevalent species were Enterococcus faecalis (82.9%) and E. faecium (12.2%). Resistance to glucopeptides (1.0%) was mediated by the vanA and vanB genes. The strains resistant to ampicillin (6%) did not produce beta-lactamases. A high percentage of resistance to aminoglycosides was observed. Gentamicin (31.0%) and streptomycin and amikacin (29.1%) were mediated by the aac(6’)Ie-aph(2”)Ia, aph(3’)-IIIa, ant(6)Ia, and ant(3”)(9) genes. A correlation was found between resistance to tetracycline (56.0%) and presence of the tet(M) (75.1%) and tet(L) genes (7.0%), while resistance to erythromycin (34.1%) was due to the erm(B) gene (70.9%). Conclusions. Resistance to vancomycin is infrequent in Cuba, as opposed to a high level of resistance to aminoglycosides, which may be indicative of treatment failures. The microbiology laboratory is a cornerstone of Enterococcus infectionsurveillance, along with ongoing monitoring of the susceptibility of these infections to antimicrobial drugs at a time when resistance of this microorganism is on the rise.

Objetivo. Identificar las especies de Enterococcus causantes de infecciones en hospitales cubanos, su susceptibilidad a los antimicrobianos y sus mecanismos de resistencia.Métodos. Se estudiaron 687 aislamientos de Enterococcus procedentes de 30 hospitalescubanos de nueve provincias del país durante el período de 2000 a 2009. La identificación de las especies se realizó mediante el método convencional y sistema automatizado API®. Laconcentración inhibitoria mínima se determinó para 13 antimicrobianos según las recomendaciones del Instituto de Estándares Clínicos y de Laboratorio. Se determinaron los genes de resistencia a aminoglucósidos, eritromicina, tetraciclina y glucopéptidos mediante reacciónen cadena de la polimerasa. La presencia de betalactamasa se determinó por el método de lacefalosporina cromógena. Resultados. Las especies más prevalentes fueron Enterococcus faecalis (82,9%) y Enterococcus faecium (12,2%). La resistencia a los glucopéptidos (1,0%) estuvo mediada por los genes vanA y vanB y las cepas resistentes a ampicilina (6%) no produjeron betalactamasas. Se observó un alto porcentaje de resistencia a los aminoglucósidos: gentamicina (31,0%) y estreptomicina y amikacina (29,1%) mediada por los genes aac(6’)Ie-aph(2”)Ia, aph(3’)-IIIa, ant(6)Ia, ant(3”)(9). Hubo correlación entre la resistencia a tetraciclina (56,0%) y la presencia de los genes tet(M) (75,1%) y tet(L) (7,0%), mientras que la resistencia a eritromicina (34,1%) obedeció al gen erm(B) (70,9%).Conclusiones. La resistencia a vancomicina es infrecuente en Cuba, a diferencia del alto nivel de resistencia a los aminoglucósidos, que sugiere posibles fracasos terapéuticos. El laboratorio de microbiología constituye un pilar fundamental de la vigilancia de las infecciones por cepas de Enterococcus y el monitoreo continuo de su susceptibilidad a los antimicrobianos,dado el incremento de la resistencia de ese microorganismo en el tiempo.

Susceptibilidad antimicrobiana y factores de virulencia en especies de Enterococcus causantes de infecciones pediátricas en Cuba / Antimicrobial susceptibility and virulence factors found in Enterococcus species causing pediatric infections

Objetivos: conocer la prevalencia de especies de enterococos causantes de infecciones en niño, su virulencia, susceptibilidad antimicrobiana e infecciones más frecuentes. Métodos: se estudiaron 156 aislamientos de enterococos causantes de infecciones en niños ingresados en el Hospital Octavio de la Concepción y La Pedraja, Holguín. Se llevó a cabo la identificación de especies y detección de factores de virulencia por métodos fenotípicos. Se determinó la concentración inhibitoria mínima para vancomicina, ciprofloxacina, ampicilina, gentamicina, estreptomicina, cloranfenicol, nitrofurantoína, eritromicina, tetraciclina, levofloxacina y norfloxacina, según las normas del Clinical Laboratory Standard Institute. Resultados: las cepas se aislaron de sangre, orina, heridas quirúrgicas, piel y tejido blando, oído medio, vulva, punta de catéter, líquido peritoneal, vagina, esperma, líquido cefalorraquídeo, y otras fuentes. La especie prevalente fue Enterococcus faecalis, seguido por Enterococcus faecium, Enterococcus gallinarum y Enterococcus raffinossus, Enterococcus casseliflavus y Enterococcus avium. La producción de proteasa y hemolisina se detectó solo en E. faecalis. E. faecium mostró porcentajes más altos de resistencia a ampicilina, ciprofloxacina, norfloxacina, levofloxacina, mientras que E. faecalis mostró más resistencia a eritromicina, cloranfenicol y tetraciclina. De E. faecalis 58 aislamientos y 12 de E. faecium presentaron altos niveles de resistencia a gentamicina, así como 45 y 32,3 por ciento mostraron altos niveles de resistencia para estreptomicina, respectivamente. Se detectó una cepa de E. faecium resistente a vancomicina. Conclusiones: la circulación de cepas de enterococos virulentas y resistentes a diferentes antibióticos indica la necesidad del control de la infección enterocócica...

Objectives: to find out the prevalence of Enterococcus species causing child infections, their virulence, antimicrobial susceptibility and most frequent infections. Methods: One hundred and fifty six isolations from Enterococcus causing infections in children, admitted to Octavio de la Concepción y La Pedraja hospital in Holguin, were studied. The phenotypical methods allowed identifying species and detecting virulence factors. Following Clinical Laboratory Standard Institute requirements, minimal inhibitory concentration was determined for vancomycin, ciprofloxacin, ampicilline, gentamycin, streptomycin, chloranphenicol, nitrofurantoine, erythromycin, tetracycline, levofloxacin and norfloxacine. Results: Strains were isolated from the blood, the urine, surgical wounds, the skin and the soft tissue, the middle ear, the vulva, catheter point, peritoneal fluid, vagina, sperm, cerebrospinal fluid, and from other sources. The prevailing species was Enterococcus faecalis followed by Enterococcus faecium, Enterococcus gallinarum y Enterococcus raffinossus, Enterococcus casseliflavus y Enterococcus avium. Protease and hemolysin was only detected in E. faecalis. E. faecium accounted for the highest percentage of resistance to ampicillin, ciprofloxacine, norfloxacin, levofloxacin whereas E. faecalis was more resistant to erythromycin, chloranphenicol and tetracycline. Fifty eight E. faecalis isolates and 12 E. faecium isolates exhibited the highest levels of resistance to gentamycin, as well as 45 percent and 32.3 percent of samples had high levels of resistance to streptomycin respectively. A vancomycin-resistent E. faecium strain was detected. Conclusions: The circulation of virulent and multiple resistant Enterococcus strains indicates that Enterococcus infection need to be controlled and the importance of monitoring antimicrobial susceptibility...