ABSTRACT
The role of wild animals, particularly migratory birds, in the dissemination of antibiotic-resistant bacteria between geographically distant ecosystems is usually underestimated. The aim of this work was to characterize the Escherichia coli population from Franklin's gull feces, focusing on the extended-spectrum ß-lactamase (ESBL)-producing strains. In the summer of 2011, 124 fecal swabs from seagulls (1 of each) migrating from the United States and Canada to the coast of Antofagasta, north of Chile, were collected. Samples were seeded on MacConkey agar supplemented with 2 µg/ml of cefotaxime and a single colony from each plate was tested for ESBL production by the double-disk ESBL synergy test. Antibiotic susceptibility was determined by the disk diffusion method and blaESBL genes were amplified and sequenced. The genetic diversity of isolates was explored by pulsed-field gel electrophoresis (PFGE)-XbaI and multilocus sequence typing. A total of 91 E. coli isolates with high rates of antibiotic resistance were identified. Carbapenemase production was not detected, whereas 67 of the 91 (54%) isolates exhibited an ESBL phenotype due to the presence of CTX-M-15 (61.3%), CTX-M-2 (19.3%), CTX-M-22 (16.1%), and CTX-M-3 (1.6%) coding genes. High genetic diversity was observed, with 30 PFGE patterns and 23 sequence types (STs), including ST131 (18%), ST44 (15%), ST617 (9%), and ST10 (9%). Results presented here are complementary to those previously reported by Hernández et al. in the same gull species, but located in the Central Region of Chile. Differences observed between gulls from both areas lead us to hypothesize that gulls from the northern location retain, as gut carriers, those resistant bacteria acquired in the United States and/or Canada.
Subject(s)
Charadriiformes/microbiology , Escherichia coli Proteins/genetics , Escherichia coli/isolation & purification , beta-Lactamases/genetics , Animal Migration , Animals , Chile , Electrophoresis, Gel, Pulsed-Field , Escherichia coli/enzymology , Escherichia coli/genetics , Feces/microbiology , Genes, Bacterial , Genetic Variation , Intestines/microbiology , Multilocus Sequence Typing , North America , beta-Lactam ResistanceABSTRACT
BACKGROUND: Enterococcus is one of the major human pathogens able to acquire multiple antibiotic-resistant markers as well as virulence factors which also colonize remote ecosystems, including wild animals. In this work, we characterized the Enterococcus population colonizing the gut of Chilean Altiplano camelids without foreign human contact. MATERIAL AND METHODS: Rectal swabs from 40 llamas and 10 alpacas were seeded in M-Enterococcus agar, and we selected a total of 57 isolates. Species identification was performed by biochemical classical tests, semi-automated WIDER system, mass spectrometry analysis by MALDI-TOF (matrix-assisted laser desorption/ionization with a time-of-flight mass spectrometer), and, finally, nucleotide sequence of internal fragments of the 16S rRNA, rpoB, pheS, and aac(6)-I genes. Genetic diversity was measured by pulsed field gel electrophoresis (PFGE)-SmaI, whereas the antibiotic susceptibility was determined by the WIDER system. Carriage of virulence factors was explored by polymerase chain reaction (PCR). RESULTS: Our results demonstrated that the most prevalent specie was Enterococcus hirae (82%), followed by other non-Enterococcus faecalis and non-Enterococcus faecium species. Some discrepancies were detected among the identification methods used, and the most reliable were the rpoB, pheS, and aac(6)-I nucleotide sequencing. Selected isolates exhibited susceptibility to almost all studied antibiotics, and virulence factors were not detected by PCR. Finally, some predominant clones were characterized by PFGE into a diverse genetic background. CONCLUSION: Enterococcus species from the Chilean camelids' gut microbiota were different from those adapted to humans, and they remained free of antibiotic resistance mechanisms as well as virulence factors.
ABSTRACT
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.
Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Enterococcus faecalis/pathogenicity , Virulence Factors/genetics , Animals , Enterococcus faecalis/drug effects , Enterococcus faecalis/genetics , Female , Humans , Microbial Sensitivity Tests , Phenotype , Poultry , Virulence/geneticsABSTRACT
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.
Subject(s)
Animals , Female , Humans , Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Enterococcus faecalis/pathogenicity , Virulence Factors/genetics , Enterococcus faecalis/drug effects , Enterococcus faecalis/genetics , Microbial Sensitivity Tests , Phenotype , Poultry , Virulence/geneticsABSTRACT
Staphylococcus aureus resistant to methicillin (SARM) has been associated with nosocomial infections due to its capacity to develop resistance to multiple antibiotics. There is little information about the SARM which are found in the hospital services of Antofagasta. We studied the phenotypic and genotypic characteristics of methicillin resistance in 38 strains of S. aureus isolated in Antofagasta, identified by coagulase and API Staph tests and by a biochemical test (Ph-system). The susceptibility to antibiotics was studied using the agar dilution technique, identifying SARM strains with discs of oxacillin. Beta-lactamase with nitrocephine, and the gene mecA by means of PCR. Eighty nine percent (34 strains) were SARM with a high resistance to ampicillin, penicillin, erythromycin, claritromycin. gentiamycin, amikacine and ciprofloxacine. All isolates were susceptible to vancomycin and rifampicin. Beta-lactamase was demonstrated in 79% of the SARM strains. Strain typing and resistance patterns revealed a great diversity of PhP-types and antibiotypes in the isolates. Ninety seven percent of the SARM strains had the gene mecA. One PhP-type (C6) was dominant (5 SARM strains) all had the mecA gene, produced beta lactamase and had the same pattern of antibiotic resistance. We conclude that the dominant phenotypes of SARM strains which have the mecA gene and multiple resistance to antibiotics are present in the hospitals of Antofagasta, and sound the alert on the risk of nosocomial transmission of epidemic clones of SARM.
Staphylococcus aureus resistentes a meticilina (SARM) han sido asociados con infecciones nosocomiales por su capacidad para desarrollar resistencia a múltiple antibióticos, existiendo escasa información acerca de SARM que están circulando en los servicios hospitalarios de Antofagasta. Se estudió características fenotIpicas y genotípicas de la resistencia a meticilina en 38 cepas de S. aureus aisladas en Antofagasta, identificadas por tests de coagulasa y API Staph y por tipificación bioquímica (Ph-Sistem). La susceptibilidad a antibióticos se realizo por técnica de dilución en agar, las cepas SARM fueron identificadas con discos de oxacilina, beta-lactamasa por nitrocefina y gen mecA fue detectado pot PCR. El 89% (34 cepas), fueron SARM con una alta resistencia a ampicilina, penicilina, eritromicina, gentamicina, amikacina y ciprofloxacino. Todos los aislados fueron susceptibles a vancomocina y rifampicina. Beta lactamasa fue demostrada en 79% de las cepas SARM. La tipificación y los patrones de resistencia revelaron una alta diversidad de PhP tipos y antibioticos en los aislamientos. El 97% de las cepas SARM albergaban el gen mecA. Un PhP tipo (C6) fue dominante. (5 cepas SARM), todos presentando el gen mecA, produciendo beta lactamasa y mostrando el mismo patrón de resistencia antibiótica. Se concluye que los fenotipos dominantes de cepas SARM que albergan el gen mecA y resistencia múltiples alos antibióticos están circulando en los hospitales de Antofagasta, alertando sobre el riesgo de transmisión intranosocomial de clones epidémicos de SARM.
