Molecular epidemiology of multi-resistant Escherichia coli

Increased Severity of Escherichia Coli Peritonitis in Peritoneal Dialysis Patients Independent of Changes in in Vitro Antimicrobial Susceptibility Testing

Objective

Despite improvements in peritoneal dialysis (PD) technique, peritonitis continues to be one of the most frequent complications of PD. Nonresolving peritonitis remains a risk for severe anatomical peritoneal changes that may limit the viability of the membrane for dialysis purposes. We have observed remarkably poor outcome of peritonitis caused by Escherichia coli in the past 6 years. With its very low response rate to broad-spectrum antibiotics, the increased severity of E. coli peritonitis deteriorates peritoneal function and affects patient outcome.

Design

Retrospective study.

Setting

Two large PD units in two university hospitals.

Patients and Methods

The total number of patients reviewed was 456. The records of 49 E. coli peritonitis episodes were studied. The observation period started in 1980 and ended in March 2001. Sixteen males and 19 females were included. Severity was defined in terms of days of peritoneal inflammation, lack of response to a potentially useful antibiotic, requirement for catheter removal, and/or laparotomy. Study cases (study group) were those episodes appearing after 1996 (when the first severe cases appeared) and historic controls were episodes occurring before1996.

Results

In the study group, 18 peritonitis episodes developed in 15 patients. In the control group, 31 peritonitis episodes developed in 20 patients. There were no significant differences in clinical presentation; however, the outcome was significantly poorer for the later period. A severe outcome occurred in 50% of study versus 10% of control patients. In fact, 68% of the episodes registered before 1996 were cured in 3 days or less. Concurring with this trend, the numbers of surgical interventions and catheter removals were also higher in the study group. Strikingly, E. coli did not show changes in in vitro susceptibility testing to antibiotics, although the in vivo response was much worse.

Conclusions

We describe a change in the virulence of E. coli peritonitis episodes over the past 5 years leading to a high percentage of treatment failure, which does not depend on antibiotic sensitivity and seems to be dependent on changes in host response mechanisms.

Postoperative infectious complications in our early experience with holmium laser enucleation of the prostate for benign prostatic hyperplasia

Purpose

The objective of this study was to retrospectively investigate postoperative infectious complications (PICs) in our early experience with holmium laser enucleation of the prostate (HoLEP) followed by mechanical morcellation for symptomatic benign prostatic hyperplasia.

Materials and Methods

A retrospective review was performed of the clinical data for 90 consecutive patients who underwent HoLEP at our institution between February 2008 and March 2011. All patients were evaluated for the emergence of PICs, including prophylactic antibiotic administration (PAA) and the influence of the kind or duration of PAA on PIC. The details of cases with PICs were also examined.

Results

The patients' mean age was 71 years (range, 50 to 95 years), and their mean prostate volume was 60 mL (range, 2 to 250 mL). There were 7 cases (7.78%) with PICs; in detail, 3 patients were diagnosed with prostatitis, 2 with pyelonephritis, and 2 with epididymitis. Three patients had positive urine cultures: 1 had Serratia marcescens/Proteus mirabilis, 1 had S. marcescens, and 1 had Klebsiella pneumonia; only one case had urological sepsis. Our statistical data showed no significant differences between 2 or fewer days and 3 or more days of PAA and PIC occurrence. There was also no significant effect on PIC occurrence of sulbactam/ampicillin compared with other antibiotics.

Conclusions

The results of this retrospective study showed that PIC occurrence did not depend on the duration or the kind of PAA. Further prospective study is necessary for the evaluation and establishment of prophylactic measures for PICs.

Matching criteria in case-control studies in the field of antimicrobial resistance

OBJECTIVE

We evaluated the available evidence from case-control studies in the field of antimicrobial resistance to identify the degree that matching was performed and the criteria used to do so.

METHODS

We performed a systematic search of the PubMed database (articles archived by 08/2006) to identify relevant studies. Studies that used the individual matching technique were further analyzed.

RESULTS

115 case-control studies with a focus on antimicrobial resistance were identified: 28 regarding Acinetobacter baumannii, 25 regarding Pseudomonas aeruginosa, and 62 for other bacteria. Individual matching was performed in 32 (27.8%) out of the 115 studies. Age was the most frequently used matching criterion in 22 of 32 (69%) evaluated matched case-control studies, while sex was used in 11 (34%), presence of underlying illness in 8 (25%), site of infection in 5 (16%), and area of residence in 4 studies (12.5%). Other criteria were used in less than 10% of the studies. Analysis of data for matched pairs was performed in 18 of 32 (56.3%) studies that used a matched case-control design.

DISCUSSION

The available evidence from the analyzed data from case-control studies in the field of antimicrobial resistance shows that individual matching is employed only in a proportion of such studies and only for a few characteristics, when it was used. Also, analysis for matched pairs was not used by almost a half of the relevant studies.

Enterobacteriaceae

This review summarises the changing epidemiology of resistance to cephalosporins and fluoroquinolones among the Enterobacteriaceae since the 1980s and its potential impact on prescribing choices now and in the immediate future. Whilst multiresistant Enterobacteriaceae are not a novel problem for high-risk hospital units, such as intensive care, the emergence of Escherichia coli co-expressing extended-spectrum beta-lactamases, such as CTX-M types, along with fluoroquinolone resistance in the community is starting to impact in situations where cephalosporins and ciprofloxacin were seen as reliable first-line choices. The reduction in effective options to treat these infections, particularly of the urinary tract and bacteraemia, is likely to result in increased prescribing of carbapenems, thus generating further selective pressure for carbapenemases and other mechanisms of carbapenem resistance in the future.

Relatedness of Escherichia coli strains with different susceptibility patterns isolated from beagle dogs during ampicillin treatment

The aim of this study was to investigate the effects of ampicillin treatment on selection and diversity of ampicillin-resistant intestinal Escherichia coli in beagles treated with ampicillin, ampicillin + beta-lactamase (targeted to degrade antibiotic residues in the gut) or placebo. Selected faecal (n = 339) and jejunal (n = 63) E. coli isolates with known resistance patterns were typed using pulsed-field gel electrophoresis (PFGE). Among the 25 detected PFGE types, ampicillin resistance was detected in 6, none of which was dominant over others among the dogs. The resistant types increased especially in the ampicillin group, whilst beta-lactamase inhibited their emergence. Selection of genetically unrelated resistant strains rather than emerging resistance among previously susceptible strains accounts for increasing resistance rates during ampicillin treatment.

DNA Decontamination: Novel DNA-ExitusPlus™ in comparison with conventional reagents

Advanced experiments in gene technology demonstrate that even small amounts of free DNA molecules are sufficient to cause infections, re-combinations or biological transformations and new methods with extremely low detection limits for the presence of DNA molecules have been developed. Therefore, detection of DNA contaminations or prevention of amplification artifacts in PCR experiments are essential in all applications. Accordingly, the complete decontamination of equipment and laboratory surfaces from any DNA molecules is important for biological containment and safety. These new developments motivated us to investigate the molecular mechanism of action of our product DNA-Exitus™ in comparison to other commercially available DNA decontamination reagents. Two major problems were apparent: First, none of the conventional reagents destroyed DNA molecules efficiently and second, all reagents contained components with corrosive or even toxic properties. Consequently, we saw the necessity to develop new solutions for effective DNA decontamination. For the first time we present the completely new DNA decontamination reagent DNA-ExitusPlus™. In comparison with conventional products, DNA-ExitusPlus™ guarantees fast and efficient destruction of nucleic acids without corrosive or toxic properties.

Endemic occurrence of infections by multidrug-resistantEscherichia coliof four unique serotypes in the elderly population of Israel

During a period of four years, multidrug-resistant Escherichia coli of particular serotypes have been isolated from 255 elderly (>65 years) patients from four hospitals in central Israel. 83% of the isolates belonged to one of four predominant serotypes (O153:H31, O101:H-, O2:H42, and O102:H6). All isolates were producers of extended spectrum beta-lactamases and resistant to ciprofloxacin. To our knowledge, the involved serotypes have hitherto not been reported as etiological agents of extraintestinal human infections (MEDLINE). Pulsed-field gel electrophoresis of isolates from one of the most frequent serotypes indicated a clonal relationship between them. Further investigation of these strains and analysis of their virulence factors may help to confine their spread.

Urinary tract infections: what's new?

PURPOSE

This review provides practicing urologists with important basic information about urinary tract infections (UTIs) that can be applied to everyday clinical problems.

MATERIALS AND METHODS

A review is presented of provocative and controversial concepts in the current literature.

RESULTS

Bacterial virulence mechanisms are critical for overcoming the normal host defenses. Increasing antimicrobial resistance of uropathogens has led to reconsideration of traditional treatment recommendations in many areas. For effective patient management the first issue is to define complicating urological factors. Managing complicated urinary tract infections, particularly in urology, is determined by clinical experience to define the pertinent anatomy and to determine the optimal interventions. New clinical data are summarized on UTIs in long-term care patients, behavioral risks for UTI in healthy women and anatomical differences associated with an increased risk for UTI. The rationale is presented for UTI prophylaxis using cranberry juice, immunization and bacterial interference. Current treatment trends for UTI include empiric therapy (without urine culture and sensitivity testing), short-course therapy, patient-administered (self-start) therapy and outpatient therapy for uncomplicated pyelonephritis.

CONCLUSIONS

Recommendations for treating patients with UTIs have changed based on basic science and clinical experience.

Characterization of multidrug-resistant Escherichia coli isolates associated with nosocomial infections in dogs

Multidrug-resistant opportunistic pathogens have become endemic to the veterinary hospital environment. Escherichia coli isolates resistant to 12 antibiotics were isolated from two dogs that were housed in the intensive care unit at The University of Georgia Veterinary Teaching Hospital within 48 h of each other. Review of 21 retrospective and prospective hospital-acquired E. coli infections revealed that the isolates had similar antibiotic resistance profiles, characterized by resistance to most cephalosporins, beta-lactams, and the beta-lactamase inhibitor clavulanic acid as well as resistance to tetracycline, spectinomycin, sulfonamides, chloramphenicol, and gentamicin. E. coli isolates with similar resistance profiles were also isolated from the environment in the intensive care unit and surgery wards. Multiple E. coli genetic types were endemic to the hospital environment, with the pulsed-field gel electrophoresis fingerprint identified among E. coli isolates from diseased animals and the hospital environment matching. The extended-spectrum cephalosporin resistance in these nosocomial E. coli isolates was attributed to the cephamycinase-encoding gene, bla(CMY2). Chloramphenicol resistance was due in part to the dissemination of the florfenicol resistance gene, flo, among these isolates. Resistance encoded by both genes was self-transmissible. Although bla(CMY2) and flo were common to the polyclonal, nosocomial E. coli isolates, there was considerable diversity in the genetic compositions of class 1 integrons, especially among isolates belonging to the same genetic type. Two or more integrons were generally present in these isolates. The gene cassettes present within each integron ranged in size from 0.6 to 2.4 kb, although a 1.7-kb gene cassette was the most prevalent. The 1.7-kb gene cassette contained spectinomycin resistance gene aadA5 and trimethoprim resistance gene dfrA17.