Clustering of enterococcal infections in a general intensive care unit

Etiology and antimicrobial resistance patterns in pediatric urinary tract infection

BACKGROUND

Urinary tract infection (UTI) is one of most common pediatric infections. The aim of this study was to investigate the etiology and antimicrobial resistance patterns in children hospitalized at Children's Hospital of Nanjing Medical University.

METHODS

We conducted a retrospective, descriptive study of all UTI from 1 January 2013 to 30 November 2016 in children discharged from Nanjing Children's Hospital. The isolated pathogens and their resistance patterns were examined using midstream urine culture.

RESULTS

A total of 2,316 children with UTI were included in the study. The occurrence rates of isolated pathogens were as follows: Enterococcus spp., 35.15%; Escherichia coli, 22.32%; Staphylococcus aureus spp., 7.73%; Streptococcus spp., 7.51%; and Klebsiella spp., 6.95%. Uropathogens had a low susceptibility to linezolid (3.47%), vancomycin (0.92%), imipenem (5.74%), and amikacin (3.17%), but they had a high susceptibility to erythromycin (90.52%), penicillin G (74.01%), cefotaxime (71.41%), cefazolin (73.41%), cefuroxime (72.52%), and aztreonam (70.11%).

CONCLUSIONS

There is high antibiotic resistance in hospitalized children with UTI. Susceptibility testing should be carried out on all clinical isolates, and the empirical antibiotic treatment should be altered accordingly.

Molecular detection of virulence factors among food and clinical Enterococcus faecalis strains in South Brazil

The present report aimed to perform a molecular epidemiological survey by investigating the presence of virulence factors in E. faecalis isolated from different human clinical (n = 57) and food samples (n = 55) in Porto Alegre, Brazil, collected from 2006 to 2009. In addition, the ability to form biofilm in vitro on polystyrene and the β-haemolytic and gelatinase activities were determined. Clinical strains presented a higher prevalence of aggregation substance (agg), enterococcal surface protein (esp) and cytolysin (cylA) genes when compared with food isolates. The esp gene was found only in clinical strains. On the other hand, the gelatinase (gelE) and adherence factor (ace) genes had similar prevalence among the strains, showing the widespread occurrence of these virulence factors among food and clinical E. faecalis strains in South Brazil. More than three virulence factor genes were detected in 77.2% and 18.2% of clinical and food strains, respectively. Gelatinase and β-haemolysin activities were not associated with the presence of gelE and cylA genes. The ability to produce biofilm was detected in 100% of clinical and 94.6% of food isolates, and clinical strains were more able to form biofilm than the food isolates (Student’s t-test, p < 0.01). Results from the statistical analysis showed significant associations between strong biofilm formation and ace (p = 0.015) and gelE (p = 0.007) genes in clinical strains. In conclusion, our data indicate that E. faecalis strains isolated from clinical and food samples possess distinctive patterns of virulence factors, with a larger number of genes that encode virulence factors detected in clinical strains.

Dogs leaving the ICU carry a very large multi-drug resistant enterococcal population with capacity for biofilm formation and horizontal gene transfer

The enterococcal community from feces of seven dogs treated with antibiotics for 2–9 days in the veterinary intensive care unit (ICU) was characterized. Both, culture-based approach and culture-independent 16S rDNA amplicon 454 pyrosequencing, revealed an abnormally large enterococcal community: 1.4±0.8×10⁸ CFU gram⁻¹ of feces and 48.9±11.5% of the total 16,228 sequences, respectively. The diversity of the overall microbial community was very low which likely reflects a high selective antibiotic pressure. The enterococcal diversity based on 210 isolates was also low as represented by Enterococcus faecium (54.6%) and Enterococcus faecalis (45.4%). E. faecium was frequently resistant to enrofloxacin (97.3%), ampicillin (96.5%), tetracycline (84.1%), doxycycline (60.2%), erythromycin (53.1%), gentamicin (48.7%), streptomycin (42.5%), and nitrofurantoin (26.5%). In E. faecalis, resistance was common to tetracycline (59.6%), erythromycin (56.4%), doxycycline (53.2%), and enrofloxacin (31.9%). No resistance was detected to vancomycin, tigecycline, linezolid, and quinupristin/dalfopristin in either species. Many isolates carried virulence traits including gelatinase, aggregation substance, cytolysin, and enterococcal surface protein. All E. faecalis strains were biofilm formers in vitro and this phenotype correlated with the presence of gelE and/or esp. In vitro intra-species conjugation assays demonstrated that E. faecium were capable of transferring tetracycline, doxycycline, streptomycin, gentamicin, and erythromycin resistance traits to human clinical strains. Multi-locus variable number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE) of E. faecium strains showed very low genotypic diversity. Interestingly, three E. faecium clones were shared among four dogs suggesting their nosocomial origin. Furthermore, multi-locus sequence typing (MLST) of nine representative MLVA types revealed that six sequence types (STs) originating from five dogs were identical or closely related to STs of human clinical isolates and isolates from hospital outbreaks. It is recommended to restrict close physical contact between pets released from the ICU and their owners to avoid potential health risks.