Prevalence and pathogenesis of extended-spectrum beta-lactamase producing Escherichia coli causing urinary tract infection in hospitalized patients

Numerical interpretation of TRS-PCR profiling results for Escherichia coli strains isolated from patients with bacteriuria in Lodz region, Poland

With the multiplicity of existing methods to track E. coli infections, it still seems necessary to seek new, better and/or complementary ways for epidemiological investigations. Particularly, fast, cheap, effective and reproducible methods providing easily comparable results are needed. Our previous studies showed that the use of TRS-PCR is an effective molecular tool in E. coli epidemiology. In this paper, we have developed a unique classification scheme in which an individual TRS-PCR pattern is assigned a numerical value. This approach allows for rapid interpretation of the results obtained from several similarity dendrograms. Using this approach, based on CAC-PCR, GTG-PCR and CGG-PCR, we obtained 52, 86 and 99 different numerical types for the 124 analyzed uropathogenic E. coli strains, respectively. This allowed for the identification of 121 unique isolates differing in at least one TRS-PCR class. In this approach, we got numerical results, easy to sort and interpret, allowing easier analysis of these strains.

Invasion and translocation of uropathogenic Escherichia coli isolated from urosepsis and patients with community-acquired urinary tract infection

Uropathogenic Escherichia coli (UPEC) strains are found in high numbers in the gut of patients with urinary tract infections (UTIs). We hypothesised that in hospitalised patients, UPEC strains might translocate from the gut to the blood stream and that this could be due to the presence of virulence genes (VGs) that are not commonly found in UPEC strains that cause UTI only. To test this, E. coli strains representing 75 dominant clonal groups of UPEC isolated from the blood of hospitalised patients with UTI (urosepsis) (n = 22), hospital-acquired (HA) UTI without blood infection (n = 24) and strains isolated from patients with community-acquired (CA)-UTIs (n = 29) were tested for their adhesion to, invasion and translocation through Caco-2 cells, in addition to the presence of 34 VGs associated with UPEC. Although there were no differences in the rate and degree of translocation among the groups, urosepsis and HA-UTI strains showed significantly higher abilities to adhere (P = 0.0095 and P < 0.0001 respectively) and invade Caco-2 cells than CA-UTI isolates (P = 0.0044, P = 0.0048 respectively). Urosepsis strains also carried significantly more VGs than strains isolated from patients with only UTI and/or CA-UTI isolates. In contrast, the antigen 43 allele RS218 was found more commonly among CA-UTI strains than in the other two groups. These data indicate that UPEC strains, irrespective of their source, are capable of translocating through gut epithelium. However, urosepsis and HA-UTI strains have a much better ability to interact with gut epithelia and have a greater virulence potential than CA-UPEC, which allows them to cause blood infection.

Antimicrobial resistance of 3 types of gram-negative bacteria isolated from hospital surfaces and the hands of health care workers

BACKGROUND

There has been an increased focus in recent years on antimicrobial resistance of bacteria isolated from clinical samples. However, resistance of bacteria from hospital environments has been less frequently investigated.

METHODS

According to hygienic standard for disinfection in hospitals, samples were collected from hospital inanimate surfaces and the hands of health care workers after daily cleaning. An automatic microorganism analyzer was used to identify bacteria and test for antimicrobial susceptibility. Polymerase chain reaction was used to detect antimicrobial resistance genes.

RESULTS

The detection rate of bacteria in general wards was significantly higher than that in intensive care units. The isolates were predominantly gram-negative (GN) bacteria, with Pseudomonas aeruginosa, Enterobacter cloacae, and Klebsiella pneumoniae being the most common. P aeruginosa isolates from other surfaces were much higher than those from medical instruments. E cloacae was isolated more frequently from the hands of other staff than medical staff. Most P aeruginosa and K pneumoniae were resistant to sulfonamides and β-lactam antimicrobials. Only 1 strain of P aeruginosa and 1 strain of K pneumoniae showed multiple antimicrobials resistance.

CONCLUSIONS

The GN bacteria isolated from hospital environments demonstrate variable resistance to antimicrobials.

The incidence and risk factors of resistant E. coli infections after prostate biopsy under fluoroquinolone prophylaxis: a single-centre experience with 2215 patients

We evaluated the incidence and risk factors of resistant Escherichia coli infections after the prostate biopsy under flouroquinolone prophylaxis. From January 2003 to December 2012, we retrospectively evaluated the records of 2215 patients. The risk factors were described for infective complications and resistant E. coli in positive cultures was calculated. Of 2215 patients, 153 had positive urine cultures, such as 129 (84·3%) E. coli, 8 (5·2%) Enterococcus spp., 6 (3·9%) Enterobacter spp., 5 (3·2%) Pseudomonas spp., 3 (1·9%) MRCNS, and 2 (1·3%) Klebsiella spp. Of the positive urine cultures which yielded E. coli, 99 (76·7%) were evaluated for fluoroquinolone resistance. Of those, 83 (83·8%) were fluoroquinolone-resistant and composed of 51 (61·4%) extended-spectrum beta-lactamase (ESBL)-positive. Fluoroquinolone-resistant E. coli ratios were 73·4 and 95·9% before 2008 and after 2008, respectively (P = 0·002). The most sensitive antibiotics for fluoroquinolone-resistant E. coli strains were imipenem (100%), amikacin (84%) and cefoperazone (83%). The use of quinolones in the last 6 months and a history of hospitalization in the last 30 days were found to be significant risk factors. We found that resistant E. coli strains might be a common microorganism in patients with this kind of complication. The risk factors for development of infection with these resistant strains were history of the use of fluoroquinolones and hospitalization.

Empirical therapies among adults hospitalized for community-acquired upper urinary tract infections: A decision-tree analysis of mortality, costs, and resistance

BACKGROUND

Poor outcomes occur when patients with serious infections receive antibiotics to which the organisms are resistant.

METHODS

Decision trees simulated in-hospital mortality, costs, incremental cost-effectiveness ratio per life year saved, and carbapenem resistance according to 3 empirical antibiotic strategies among adults hospitalized for community-acquired (CA) upper urinary tract infections (UTIs): ceftriaxone (CRO) plus gentamicin (GM) in the intensive care unit (ICU), imipenem (IMP), and individualized choice (IMP or CRO) based on clinical risk factors for CA- extended-spectrum β-lactamase (ESBL).

RESULTS

The estimated prevalence of CA-ESBL on admission was 5% (range, 1.3%-17.6%); 3% and 97% were admitted to the ICU and medical ward (MW), respectively. In the ICU, CRO plus GM was dominated; IMP was cost-effective (incremental cost-effectiveness ratio: €4,400 per life year saved compared with individualized choice). In the MW, IMP had no impact on mortality and was less costly (-€142 per patient vs CRO, -€38 vs individualized choice). The dominance of IMP was consistent in sensitivity analyses. Compared with CRO, colonization by carbapenem-resistant pathogens increased by an odds ratio of 4.5 in the IMP strategy.

CONCLUSION

Among the ICU patients, empirical IMP therapy reduces mortality at an acceptable cost. Among MW patients, individualized choice or CRO is preferred to limit carbapenem resistance at a reasonable cost.

Antibiotic resistance pattern of different Escherichia coli phylogenetic groups isolated from human urinary tract infection and avian colibacillosis

Background: The emergence and propagation of different phylogenetic groups of antimicrobial-resistant E. coli have become a worldwide health concern in human and veterinary medicine. Therefore, the evaluation of the phylogenetic distribution of antibiotic-resistant E. coli is important for therapeutic and economic purposes. The aims of this study were to determine phylogenetic groups and patterns of antibiotic resistance of E. coli strains isolated from human urinary tract infection and avian colibacillosis. Methods: A total of 50 E. coli isolates (25 from human urinary tract infection and 25 from avian colibacillosis) were characterized by culture and assigned as different phylogenetic groups (A, B1, B2, and D) by triplex PCR assay. Kirby-Bauer disk diffusion method was used to assess the susceptibility of all isolates to ten antibiotics. Results: Results showed that the majority of the human and poultry isolates belonged to phylogenetic groups A and B2 and phylogenetic group B1 of the avian pathogenic strain isolates were the most drug-resistant isolates. Most of the isolates were resistant to at least five antibiotics, and multiple drug resistance was observed in 98% of E. coli isolates. A high degree of resistance was seen against penicillin and erythromycin. Conclusion: According to the results of this study, multidrug-resistance among isolates and high relation between phylogenetic groups and resistance in both human and poultry isolates were observed.

Extended-spectrum β-lactamase producing Escherichia coli in hospital wastewaters and sewage treatment plants in Queensland, Australia

We investigated the prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in untreated hospital wastewaters and 2 sewage treatment plants (STPs). A collection of 252 ESBL-producing E. coli isolates from hospital wastewater and STPs were typed and tested for resistance to 17 antimicrobial agents and for the presence of integron-associated integrases (intI gene) and ESBL genes. Eighty-nine percent (n = 176) of the ESBL-producing E. coli strains from hospital wastewater were found in more than 1 sample (common types), with 1 common type accounting for 35% of isolates, found in all samples. These strains were also resistant to up to 9 non-β-lactam antibiotics and showed the same pattern of resistance in all samples. More than 73% of the hospital wastewater isolates possessed SHV-type ESBL as opposed to isolates from STPs that carried only CTX-M-type ESBL genes. The prevalence of the intI gene did not differ between the sources of the isolates. Certain ESBL-producing E. coli were dominant in hospital wastewaters. These strains possessed β-lactamase genes that were different from isolates found in STPs. From a public health point of view, the presence of such a high level of ESBL-producing E. coli strains in hospital wastewaters is of great importance.

Extended-spectrum cephalosporin-resistant Gram-negative organisms in livestock: an emerging problem for human health?

Escherichia coli, Salmonella spp. and Acinetobacter spp. are important human pathogens. Serious infections due to these organisms are usually treated with extended-spectrum cephalosporins (ESCs). However, in the past two decades we have faced a rapid increasing of infections and colonization caused by ESC-resistant (ESC-R) isolates due to production of extended-spectrum-β-lactamases (ESBLs), plasmid-mediated AmpCs (pAmpCs) and/or carbapenemase enzymes. This situation limits drastically our therapeutic armamentarium and puts under peril the human health. Animals are considered as potential reservoirs of multidrug-resistant (MDR) Gram-negative organisms. The massive and indiscriminate use of antibiotics in veterinary medicine has contributed to the selection of ESC-R E. coli, ESC-R Salmonella spp. and, to less extent, MDR Acinetobacter spp. among animals, food, and environment. This complex scenario is responsible for the expansion of these MDR organisms which may have life-threatening clinical significance. Nowadays, the prevalence of food-producing animals carrying ESC-R E. coli and ESC-R Salmonella (especially those producing CTX-M-type ESBLs and the CMY-2 pAmpC) has reached worryingly high values. More recently, the appearance of carbapenem-resistant isolates (i.e., VIM-1-producing Enterobacteriaceae and NDM-1 or OXA-23-producing Acinetobacter spp.) in livestock has even drawn greater concerns. In this review, we describe the aspects related to the spread of the above MDR organisms among pigs, cattle, and poultry, focusing on epidemiology, molecular mechanisms of resistance, impact of antibiotic use, and strategies to contain the overall problem. The link and the impact of ESC-R organisms of livestock origin for the human scenario are also discussed.