Enterococcus in wound infections: virulence and antimicrobial resistance.

Enterococci, a complex group of facultative pathogens have become increasingly isolated in various hospital settings. They are considerable frequently cultured from traumatic and surgical wounds. We investigated 57 strains of the species E. faecalis, E. faecium and E. casseliflavus isolated from infected wounds. Their ability to produce virulence factors and their sensitivity to antibiotics were evaluated using phenotypic and genotyping methods. In the phenotype studies, significant portion of the isolates produced biofilm (66.7%) and gelatinase (36.8%). Nearly 30% of the strains expressed hemolytic properties. Only a few produced DNAse (15.8%) and lipase (7.0%). The genes esp, gelE, cylA, cylB, cylM and agg were detected in most of the isolates (38.6-87.7%). All the isolated enterococci were susceptible to vancomycin and were characterized by their low resistance to antibiotics, except aminoglycosides (HLR).

[Estimation of level of aminoglycosides susceptibility of bacterial strains isolated from patients with systemic and general infections]. / Ocena stopnia wrazliwosci na aminoglikozydy szczepów bakteryjnych izolowanych od chorych z zakazeniami ukladowymi i uogólnionymi.

Susceptibility tests to aminoglycosides of 200 bacterial strains isolated in period 1.01.2007-30.04.2008 from hospitalized patients in different Wroclaw clinics were performed. Among tested strains were 96 Gram-negative rods belonging to the Enterobacteriaceae family, 74 non-fermentative rods and 30 strains of Staphylococcus aureus. The results of antibiotic susceptibility determined by serial antibiotic dilution in solid medium indicated that among Enterobacteriaceae the most susceptible to aminoglycosides were E. coli (90-95%) and least susceptible Enterobacter spp., Citrobacter spp. and Serratia spp (62-76%). Among non-fermentative rods, Pseudomonas aeruginosa was more susceptible than Acinetobacter spp. 97% strains of Staphylococcus aureus were susceptible to all aminoglycosides. Enterobacteriaceae strains isolated from adults were more resistant to aminoglycosides than isolated from children and non-fermentative rods isolated from adults more susceptible to netilmicin. Among S. aureus only one strains was MRSA and aminoglycoside resistant. Twenty two of 96 examined strains belonging to Enterobacteriaceae and 46 of 74 examined non-fermentative rods were resistant at least to one aminoglycoside. Predominant resistance patterns were as follow: simultaneous resistance to all aminoglycosides and resistance to gentamicin and netilmicin with susceptible to amikacin. High level resistance (MIC > or = 256 microg/ml) was found in 23 gentamicin resistant strains (12 rods of Enterobacteriaceae and 11 non-fermentative rods), in 33 netilmicin resistant strains (respectively 10 and 21 strains) and in 14 amikacin resistant Gram-negative rods (respectively 9 and 5 strains). Among 96 rods of Enterobacteriaceae family 19 ESBL (+) strains were found. High level of resistance (MIC > or = 256 microg/ml) was found in 10 ESBL (+) strains.

[Conjugative transfer frequency of resistance genes from ESBL-producing Enterobacteriaceae strains isolated from patients hospitalized in pediatric wards]. / Czestosc koniugacyjnego transferu genów lekoopornosci z ESBL-dodatnich paleczek Enterobacteriaceae izolowanych od chorych z oddzialow pediatrycznych.

The aim of this study was to evaluate the transfer frequency of plasmids encoding extended-spectrum beta-lactamases (ESBLs) from clinical isolates of Enterobacteriaceae to E. coli K12 C600 recipient strain. Additionally, resistance patterns to antimicrobial drugs of the isolates as well as transconjugants were analyzed. Fifty-four clinical strains belonging to the Enterobacteriaceae family were isolated from children hospitalized in Medical University Hospital in Wroclaw. All the strains studied were identified in automatic ATB system using ID32E tests. Besides, they were ESBL-positive as was confirmed by the double-disc synergy test (DDST). The minimal inhibitory concentration (MIC) was determined for twelve selected antibiotics and chemotherapeutics. The majority of the strains (87%) were able to transfer plasmid-mediated ESBL to E. coli K12 C600 recipient strain with a frequencies ranged from 10(-5) to 10(-1) per donor cell. All the isolates studied as well as their transconjugants were susceptible to imipenem, meropenem and norfloxacin (MIC <1mg/L). On the other hand, these strains displayed high level of resistance (MIC 512 - >1024 mg/L) to cefotaxime, ceftriaxone, gentamycin, amikacin and cotrimoxazole. Genetic markers conferring resistance to aminoglycosides and cotrimoxazole were often co-transferred to recipient strain in conjugation process.