Phenotypes of Escherichia coli isolated from urine: Differences between extended-spectrum ß-lactamase producers and sensitive strains.

BACKGROUND: Escherichia coli is a frequent causative agent of urinary tract infections, and increasing resistance of E. coli to antimicrobials presents a growing challenge. METHODS: Here we compare phenotypes of extended-spectrum ß-lactamase (ESBL) producers (n = 220) with a control group of sensitive strains (non-ESBL producers; n = 150). For each strain, we assessed the presence of O25 antigen, hemolysis, biofilm production, sensitivity to antibiotics, and biochemical profile. RESULTS: Compared to the control group, ESBL producers were more frequently O25 positive (6.0% vs. 42.3%) and less frequently hemolytic (34.7% vs. 6.4%). Comparison of biofilm production in brain-heart infusion (BHI) and in BHI with 4% glucose supplementation showed that ESBL-positive strains produced biofilm in BHI with glucose less intensely than the control group (p < 0.05). Most ESBL producers were ciprofloxacin-resistant (91.8%). Biochemical analyses revealed that ESBL producers more frequently utilized inositol, ornithine, sorbitol, melibiose, and saccharose, whereas the control group more frequently used esculin, lysine, arginine, and dulcitol. The control group strains with O25 antigen were more commonly resistant to ciprofloxacin (p < 0.05). Pulsed-field gel electrophoresis results showed higher variability among the control group of sensitive strains. CONCLUSION: These findings suggest a potential to detect ESBL strains based on virulence factors and biochemical properties, which could be useful in shaping proper empiric antimicrobial therapy, and for initiating such therapy as soon as possible.

Characterization of human uropathogenic ESBL-producing Escherichia coli in the Czech Republic: spread of CTX-M-27-producing strains in a university hospital.

AIMS: The purpose of this study was to characterize the extended-spectrum ß-lactamase (ESBL)-producing uropathogenic Escherichia coli (UPEC) strains isolated in the South Moravia region of the Czech Republic. RESULTS: Out of 109 ESBL-producing UPEC isolates, the CTX-M-15-producing E. coli O25b-ST131 was detected in 55 (50.5%) and the CTX-M-27-producing E. coli O25b-ST131 in 40 isolates (36.7%). Most isolates were distributed among three pulsed-field gel electrophoresis clusters and were characterized by low variability relative to antibiotic resistance patterns, in E. coli phylogroups and by the prevalence of virulence and bacteriocin determinants. Despite this, 14 groups of identical isolates (comprising a total of 41 isolates) were identified when all tested parameters of E. coli were combined. CONCLUSIONS: Since the occurrence of E. coli B2-O25b-ST131 CTX-M-27 was only recently described in Asia, the frequent isolation of this lineage among patients in South Moravia suggests an efficient transfer of this clone from Asian countries. The limited variability of detected parameters of ESBL-producing UPEC strains is consistent with a common origin of the analyzed isolates, in which there is an ongoing process of genetic diversification.

[Proteus mirabilis isolated from urine, resistance to antibiotics and biofilm formation]. / Proteus mirabilis izolovany z moci, jeho rezistence k antibiotikum a tvorba biofilmu.

BACKGROUND: In the rather rare urinary pathogen Proteus mirabilis resistance to antibiotics and ability to form biofilm were studied. MATERIAL AND METHODS: The strains Proteus mirabilis were isolated from urine samples from ambulatory and hospitalized patients diagnosed with urinary tract infection (UTI) between April 2008 and April 2010. Resistance to antibiotics was investigated using a disk diffusion antimicrobial susceptibility test. Biofilm formation was demonstrated by modified Christensen method. RESULTS: Two hundred and thirteen of P. mirabilis strains were tested. Eighty-two (38.5 %) strains were resistant to ampicillin, 49 (23.0 %) to cefalotin, 83 (39.0 %) to sulfamethoxazole/trimetoprim, 75 (35.2 %) to ciprofloxacin, 95 (44.6 %) to oxolinic acid, 54 (25.4 %) to gentamicin, and 72 (33.8 %) to chloramphenicol. There was significantly lower resistance to cefotaxime - 8 strains (3.8 %), ceftazidime - 8 (3.8 %), amoxicillin/clavulanic acid 17 (8.0 %) and aztreonam - 8 (3.8 %). No resistance to imipenem as well as to meropenem was found. Eight P. mirabilis strains were found to produce extended-spectrum beta-lactamase (ESBL). From the total of 213 strains tested, 28 (13.1 %) were able to form a biofilm. CONCLUSIONS: P. mirabilis was found to be more frequent in urine of men and older patients. Biofilm formation in urinary P. mirabilis strains was relatively low. The strains showed higher resistance to beta-lactams and quinolones; in the other cases, resistance was low.

[Antibiotic resistance and biofilm formation in Staphylococcus aureus strains isolated from urine]. / Staphylococcus aureus, tvorba biofilmu a rezistence k antibiotikum u kmenu izolovanych z moce.

BACKGROUND: The aim of this study was to evaluate antibiotic resistance and biofilm formation of Staphylococcus aureus strains, isolated from urine samples of patients with urinary tract infection. The samples were collected in the period of 2005-2009 and originated from patients of St. Anne's Teaching Hospital in Brno. MATERIAL AND METHODS: A total of 128 S. aureus strains from 128 patients with the diagnosis of urinary tract infection were examined. In addition to testing the antibiotic resistance to doxycycline, vankomycin, nitrofurantoin, oxacillin, amoxicillin/clavulanate, cefoxitin and sulfamethoxazol/trimethoprim, biofilm was also detected in 112 strains by the modified Christensen method. RESULTS: No S. aureus strain resistant to vankomycin and nitrofrantoin was found, 12 strains were resistant to oxacillin (9.4 %), 6 to doxycyklin (4.7 %), 9 to amoxicillin/clavulanate (7.0 %) as well as to cefoxitine, and 2 to sulfamethoxazol/trimethoprim (1.6 %). Out of 20,375 positive urine samples examined in our laboratory between 2005 and 2009, S. aureus was detected as a causative agent of urinary tract infection in 0.6 %, being more frequent in males. Biofilm was produced by 14 (12.5 %) out of 112 S. aureus strains. CONCLUSIONS: The biofilm formation of urinary S. aureus strains was low. The strains showed higher resistance to beta-lactams, in other cases resistance was low. S. aureus was found to be more frequent in urine of older patients, males and after previous interventions using instrumental.