Urinary Tract Pathogens Research Articles

Effect of triclosan on the development of bacterial biofilms by urinary tract pathogens on urinary catheters

To examine (i) the effect of triclosan on the formation of catheter biofilms by urinary tract pathogens and (ii) the diffusion of triclosan through the retention balloons of urinary catheters. Models of the catheterized bladder were infected with eight different urinary tract pathogens and the effect of triclosan on biofilm formation was assessed by determining the numbers of viable cells colonizing the catheters and by scanning electron microscopy. HPLC was used to determine the triclosan concentration in urine draining from models that had been fitted with triclosan-inflated silicone catheters. When catheters were inflated with triclosan (10 g/L) the formation of catheter biofilm by Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Proteus mirabilis was prevented. The numbers of Enterococcus faecalis and Providencia stuartii cells colonizing catheters were also significantly reduced (P<0.05). Serratia marcescens, Morganella morganii and Pseudomonas aeruginosa, however, were able to produce extensive catheter biofilms in the presence of triclosan. Only P. mirabilis produced alkaline urine and encrusted the catheters. Concentrations of 0.02-0.16 mg/L of the biocide were detected in urine draining from the model over the 48 h experimental period. Triclosan diffused through silicone catheter balloons and produced urinary concentrations that prevented catheter encrustation by P. mirabilis and biofilm formation by several other common pathogens of the catheterized urinary tract. It had little effect on urease-producing P. aeruginosa, S. marcescens or M. morganii but these species did not produce alkaline urine or crystalline biofilms.

The ability of Proteus mirabilis to sense surfaces and regulate virulence gene expression involves FliL, a flagellar basal body protein.

Proteus mirabilis is a urinary tract pathogen that differentiates from a short swimmer cell to an elongated, highly flagellated swarmer cell. Swarmer cell differentiation parallels an increased expression of several virulence factors, suggesting that both processes are controlled by the same signal. The molecular nature of this signal is not known but is hypothesized to involve the inhibition of flagellar rotation. In this study, data are presented supporting the idea that conditions inhibiting flagellar rotation induce swarmer cell differentiation and implicating a rotating flagellar filament as critical to the sensing mechanism. Mutations in three genes, fliL, fliF, and fliG, encoding components of the flagellar basal body, result in the inappropriate development of swarmer cells in noninducing liquid media or hyperelongated swarmer cells on agar media. The fliL mutation was studied in detail. FliL- mutants are nonmotile and fail to synthesize flagellin, while complementation of fliL restores wild-type cell elongation but not motility. Overexpression of fliL+ in wild-type cells prevents swarmer cell differentiation and motility, a result also observed when P. mirabilis fliL+ was expressed in Escherichia coli. These results suggest that FliL plays a role in swarmer cell differentiation and implicate FliL as critical to transduction of the signal inducing swarmer cell differentiation and virulence gene expression. In concert with this idea, defects in fliL up-regulate the expression of two virulence genes, zapA and hpmB. These results support the hypothesis that P. mirabilis ascertains its location in the environment or host by assessing the status of its flagellar motors, which in turn control swarmer cell gene expression.

Noninvasive Biophotonic Imaging for Monitoring of Catheter-Associated Urinary Tract Infections and Therapy in Mice

Urinary tract infections (UTIs) are among the most common bacterial infections acquired by humans, particularly in catheterized patients. A major problem with catheterization is the formation of bacterial biofilms on catheter material and the risk of developing persistent UTIs that are difficult to monitor and eradicate. To better understand the course of UTIs and allow more accurate studies of in vivo antibiotic efficacy, we developed a catheter-based biofilm infection model with mice, using bioluminescently engineered bacteria. Two important urinary tract pathogens, Pseudomonas aeruginosa and Proteus mirabilis, were made bioluminescent by stable insertion of a complete lux operon. Segments of catheter material (precolonized or postimplant infected) with either pathogen were placed transurethrally in the lumen of the bladder by using a metal stylet without surgical manipulation. The bioluminescent strains were sufficiently bright to be readily monitored from the outside of infected animals, using a low-light optical imaging system, including the ability to trace the ascending pattern of light-emitting bacteria through ureters to the kidneys. Placement of the catheter in the bladder not only resulted in the development of strong cystitis that persisted significantly longer than in mice challenged with bacterial suspensions alone but also required prolonged antibiotic treatment to reduce the level of infection. Treatment of infected mice for 4 days with ciprofloxacin at 30 mg/kg of body weight twice a day cured cystitis and renal infection in noncatheterized mice. Similarly, ciprofloxacin reduced the bacterial burden to undetectable levels in catheterized mice but did not inhibit rebound of the infection upon cessation of antibiotic therapy. This methodology easily allows spatial information to be monitored sequentially throughout the entire disease process, including ascending UTI, treatment efficacy, and relapse, all without exogenous sampling, which is not possible with conventional methods.

Urinary tract pathogens and antimicrobial sensitivity patterns in childhood urinary tract infection, Kano Nigeria

Background : Adequate treatment and control of Urinary Tract Infection (UTI) depends on a good knowledge of the agents causing the infection. The study was designed to assess the aetiology of childhood UTI and the susceptibility of these pathogens to the commonly available antimicrobial agents. Methodology : Children aged 0-10years with symptomatic urinary tract infection seen in both in-patient and out-patients in Aminu Kano Teaching Hospital, Kano between 1st November 2002 and 31st October 2004. Results : Bacterial organisms were isolated from the urine of 145 children. The predominant isolate in both in-patient and out-patients were Escherichia coli and Klebsiella spp. Escherichia coli, Klebsiella spp, Proteus spp, Pseudomonas aeruginosa and Staphylococcus aureus accounted for 41.9%, 25.8%, 16.8%, 12.3% and 3.2% respectively. All the isolates were poorly sensitive to the common first line drugs used in childhood UTI in our environment namely cotrimazole and ampicillin but there was good sensitive to nitrofurantoin and ofloxacin. Conclusion : It is recommended that nitrofurantoin be used in the treatment of childhood UTI in Kano while results of culture and sensitivity are awaited. There should also be a continuous monitoring of pattern of organisms isolated in childhood UTI and their antibiotic resistance pattern. Keywords : childhood, UTI, pathogens Annals of Nigerian Medicine Vol. 1(2) 2005: 14-16

Resistance of catheter-associated urinary tract infections to antibacterials

Catheter-associated urinary tract infections (CAUTI) are the most common nosocomial infections. The worldwide data show the increasing resistance to conventional antibiotics among urinary tract pathogens. To evaluate the adequacy of initial antimicrobial therapy in relation to the antimicrobial resistance of pathogens responsible for CAUTI in Clinical Center of Banja Luka. A retrospective study on major causes of CAUTI, antibiotic resistance and treatment principles was conducted at four departments of the Clinical Center of Banja Luka from January 1st, 2000 to April 1st, 2003. The results showed that 265 patients had developed CAUTI. The seven most commonly isolated microorganisms were, in descending order: E. coil (31.0%), Pseudomonas aeruginosa (13.8%), Proteus mirabilis (12.9%), Gr. Klebsiella-Enterobacter (12.3%), Enterococcus spp. (5.2%), Pseudomonas spp. (4.3%), Serratia spp. (4.0%). The most common pathogens were highly resistant to ampicillin (64-100%), gentamycin (63-100%), and trimethoprim-sulfamethoxazole (68-100%), while some bacterias, like Pseudomonas aeruginosa and Serratia spp. showed rates of ciprofloxacin resistance as high as 42.8% and 72.7%, respectively. In 55.5% of the cases, the initial antibiotic therapy was inadequate, and was corrected latter on. There were no standard therapeutic protocols for this type of nosocomial infections. The results of this study emphasized an urgency of the prevention and introduction of clinical protocols for better management of CAUTI. Treatment principles should better correspond to the antibiotic sensitivity of uropathogens.

BACTERIURIA MANAGEMENT AND UROLOGICAL EVALUATION OF PATIENTS WITH SPINA BIFIDA AND NEUROGENIC BLADDER: A MULTICENTER SURVEY

We assessed how groups at spina bifida clinics evaluate and manage the urinary tract in patients with spina bifida, neurogenic bladder and bacteriuria. A survey was mailed to all 169 clinics listed by the Spina Bifida Association of America. Survey items addressed baseline and surveillance evaluation, criteria used to assess urinary tract health and approaches to treatment in patients with spina bifida and neurogenic bladder. Of the 169 clinics personnel at 59 (35%) responded to the survey. Almost half of the respondents had an established protocol or standard of care. At most clinics the use of ultrasound (93%), voiding cystourethrograms (85%) and urodynamic testing (76%) was supported but not renal isotopic studies (14%) or excretory urograms (2%) for baseline evaluation. At all clinics ultrasound was supported for routine surveillance but there was no consensus for other imaging modalities. Assessment of clinic approaches to the evaluation and management of bacteriuria demonstrated variable results, although at most clinics fever, flank pain, dysuria, and changes in urinary pattern were identified as being consistent with true infection. Groups at clinics following their protocol or standard of care showed no significant differences in their approach compared to those at clinics lacking a protocol or standard of care. No consensus exists for the evaluation and management of bacteriuria in patients with spina bifida and neurogenic bladder at clinics specializing in the care of such patients, even at those with established standards of care. A clear need exists for an established, national set of evidence based guidelines to assist medical decision making in this high risk population and, thus, improve care.

Impiego del sistema URO-QUICK per l’esecuzione rapida di antibiogrammi direttamente su campioni di urine

During the period june-october 2003 the urine samples were examined employing routine methods for strain identification and the Kirby-Bauer technique for antibiotic susceptibility tests.This usual system was compared with the new rapid Uro-Quick method employed on samples resulting positive and mono-microbial after Gram coloration. Antibiotic (in appropriate concentration) was introduced in a vial containing 2 ml of Mueller-Hinton broth, then 0.5 ml of urine were added in each vial containing the antimicrobial molecules and even in a vial without drug used as control.After 3-5 hours of incubation (for Gram negative or Gram positive strains respectively) the instrument shows the results. No growth and a growth curve like the control are representative of a susceptible and resistant strain respectively). Gram negative strain were tested against ciprofloxacin, nitrofurantoin, co-clavulanate, ceftazidime, fosfomycin, imipenem, amikacin, and trimethoprim-sulfamethoxazole, while Gram positive bacteria against ciprofloxacin, nitrofurantoin, co-clavulanate, ampicillin, fosfomycin, gentamycin, oxacillin and trimethoprim-sulfamethoxazole.The Gram negative strains isolated were 1172 and the Gram positive were 261.With the first group agreement between the two methods was always more than 90%, against Gram positive pathogens there was more than 80% of agreement. In conclusion against the mayor urinary tract pathogens (E. coli, Enterococci, Klebsiella spp. and Proteus spp.) agreement between the Uro-Quick system and the Kirby- Bauer was more than 90%.The rapid method appears useful not only for the determination of the antibiotic susceptibility of common uropathogens, but, on the basis of the present findings, it could be suggested the use of this rapid method in more severe nosocomial infections.

Transcription of Proteus mirabilis flaAB.

Proteus mirabilis, a Gram-negative urinary tract pathogen, has two highly homologous, tandemly arranged flagellin-encoding genes, flaA and flaB. flaA is transcribed from a sigma(28) promoter, while flaB is a silent allele. Previous studies have demonstrated the presence of a family of hybrid flagellin genes, referred to as flaAB. These genes are composed of the 5' end of flaA and the 3' end of flaB, and are produced through excision of the intervening DNA between the two genes. Although the existence of flaAB DNA has been documented, it was not known if transcription of flaAB occurs in wild-type P. mirabilis. In this study, proof of flaAB transcription was obtained from a combination of RNA dot-blots and RT-PCR assays using specific primers and probes for flaAB and flaA. The RNA data were further supported by the demonstration of phenotypic switching of the locus using a FlaAB-detector strain. The results show that flaAB mRNA is transcribed and is 1/64 as abundant as flaA in the population of wild-type cells, suggesting that flaAB constitutes 1.0-1.5 % of the total flagellin message. Nucleotide sequence analysis of flaAB products produced by RT-PCR from the wild-type confirms previous reports of a variable fusion site between flaA and flaB resulting in a hybrid flagellin transcript. These data support the hypothesis that the production of FlaAB is integral to the physiology of P. mirabilis.

Antibiotic resistance of urinary tract pathogens and rationale for empirical intravenous therapy

Empirical antibiotic treatment in urinary tract infection (UTI) in children must rely on surveillance data on the epidemiology and resistance patterns of common uropathogens. A retrospective analysis of bacteria isolated from children with UTI irrespective of underlying disease or pre-treatment was performed at the University Hospital of Freiburg, Germany, in 1997, and from 1999 to 2001. In the first study period, 261 positive urine samples and in the second period 684 positive samples were analyzed. Escherichia coli (57.2%) was the leading uropathogen followed by Enterococcus spp. (13.7%), Pseudomonas aeruginosa (7.0%), Proteus spp. (5.9%), Klebsiella spp. (4.7%), and Enterobacter/Citrobacter spp. (4.3%). Almost 50% of the E. coli isolates were resistant to ampicillin, but effectively no resistance against cephalosporins, aminogylcosides, ciprofloxacin, nitrofurantoin, and imipenem was observed. In Enterococcus spp. the resistance to ampicillin was about 15% and 40% to netilmicin, while none of the latter showed high-level aminoglycoside resistance. In P. aeruginosa, there was no resistance to aminoglycosides. No difference in resistance patterns between the two study periods was observed. We conclude that an empirical combination treatment of ampicillin and gentamicin, netilmicin, or tobramycin is appropriate in children with UTI independent of pre-treatment or underlying disease. This therapy should be clinically efficacious, well tolerated, and cost effective, and should prevent unnecessary development of antimicrobial resistance.

Antimicrobial resistance in Escherichia coli in urine samples from children and adults: a 12 year analysis.

To investigate the distribution and antimicrobial resistance in urinary tract pathogens, primarily Escherichia coli, in two age groups, children < or = 2 y and adults 18-50 y, over a period of 12 y. From the database of the microbiological laboratory all urinary tract culture data were extracted and structured according to date, patient age, bacteriological findings, antimicrobial susceptibility results and sample type. Statistical longitudinal analysis of bacteriological findings and antimicrobial resistance trends in the two age groups were performed. Statistical significance was obtained for the following results. Escherichia coli was the most common pathogen in both age groups and irrespective of sample type. In E. coli resistance to ampicillin and trimethoprim was higher in children than in adults and increased over time in both age groups. Resistance to fluoroquinolones was higher in adults than in children and increased over time in both groups. Resistance to pivmecillinam, cefadroxil and nitrofurantoin was below 2% in 2001 in both age groups. The steadily increasing and now high E. coli resistance levels in children to ampicillin and trimethoprim render empirical therapy with these drugs doubtful. The stable and low levels of resistance to pivmecillinam, cefadroxil and nitrofurantoin (< 2% in 2001) make these drugs reasonable alternatives in uncomplicated lower urinary tract infections.

Plasma pharmacokinetics and urine concentrations of meropenem in ewes.

The pharmacokinetics of meropenem was studied in five ewes after single i.v. and i.m. dose of 20 mg/kg bw. Meropenem concentrations in plasma and urine were determined using microbiological assay method. A two-compartment open model was best described the decrease of meropenem concentration in plasma after an i.v. injection. The drug was rapidly eliminated with a half-life of elimination (t1/2beta) of 0.39 +/- 0.30 h. Meropenem showed a small steady-state volume of distribution [Vd(ss)] 0.055 +/- 0.09 L/kg. Following i.m. injection, meropenem was rapidly absorbed with a t1/2ab of 0.25 +/- 0.04 h. The peak plasma concentration (Cmax) was 48.79 +/- 8.83 microg/mL was attained after 0.57 +/- 0.13 h (tmax). The elimination half-life (t1/2el) of meropenem was 0.71 +/- 0.12 h and the mean residence time (MRT) was 1.38 +/- 0.26 h. The systemic bioavailability (F) after i.m. injection was 112.67 +/- 10.13%. In vitro protein-binding percentage of meropenem in ewe's plasma was 42.80%. The mean urinary recoveries of meropenem over 24 h were 83% and 91% of the administered dose after i.v. and i.m. injections respectively. Thus, meropenem is likely to be efficacious in the eradication of many urinary tract pathogens in sheep.

Evaluation of a new chromogenic medium, Uriselect 4, for the isolation and identification of urinary tract pathogens

Aims: To compare the performance of a new chromogenic medium, Uriselect 4, with cystine lactose electrolyte deficient (CLED) agar and an established chromogenic agar, CPS ID 2 medium, for detection...

Validation of a decision rule identifying febrile young girls at high risk for urinary tract infection.

To validate a previously published clinical decision rule to predict risk of urinary tract infection in febrile young girls. We performed a retrospective case-control study at a children's hospital emergency department in a different city than that in which the original derivation study took place. Girls younger than 2 years in whom urinalysis and urine culture were performed for evaluation of fever were eligible. Cases consisted of all patients with a positive urine culture result, defined as 50,000 or more colony-forming units per milliliter of a urinary tract pathogen (n = 98). A random sample of patients with a negative urine culture result (n = 114) was also selected as controls. The clinical prediction rule included five risk factors: age younger than 12 months, white race, temperature of 39.0 degrees C or higher, absence of any other potential source of fever, and fever for 2 days or more. The sensitivity and false-positive rate of this rule were calculated at different cutoff values. The overall discriminative ability of the rule, as indicated by the area under the receiver-operator characteristic curve (AUC), was similar in this validation sample (AUC = 0.72) to that in the original study (AUC = 0.76). However, in the validation sample, the presence of three or more risk factors (rather than two or more as in the original study) appeared to be the optimum cutoff to define a positive rule, which results in an indication for obtaining further diagnostic testing (sensitivity, 88% [95% CI, 79-94%]; false-positive rate, 70% [95% CI, 61-79%]). A simple clinical decision rule previously developed to predict urinary tract infection based on five risk factors performs similarly in a different patient population.

The expanding role of fluoroquinolones

There has been a growing rate of resistance among common urinary tract pathogens, such as Escherichia coli, to traditional antimicrobial therapies including the “gold standard” trimethoprim-sulfamethoxazole (TMP-SMX). Consequently, fluoroquinolone antimicrobial agents have taken on an expanding management role for UTIs. In fact, the recent Infectious Diseases Society of America clinical management guidelines for UTI recommend fluoroquinolones as first-line therapy for uncomplicated UTI in areas where resistance is likely to be of concern.Fluoroquinolones have demonstrated high bacteriologic and clinical cure rates, as well as low rates of resistance, among most common uropathogens. There are currently 7 fluoroquinolones with indications for UTI in the United States. However, only 3 are commonly used: levofloxacin, ciprofloxacin, and, to a lesser extent, gatifloxacin. Many of the fluoroquinolone agents have once-daily dosing regimens, enhancing patient adherence. In addition, levofloxacin and gatifloxacin have same-dose bioequivalency between their intravenous and oral formulations, allowing for “switch” or step-down therapy from parenteral to oral formulations of the same agent at the same dose.Fluoroquinolones are indicated for the management of acute uncomplicated UTIs, as well as complicated and severe UTI and pyelonephritis, in adults. They are the first-line treatment of acute uncomplicated cystitis in patients who cannot tolerate sulfonamides or TMP, who live in geographic areas with known resistance > 10 % to 20 % to TMP-SMX, or who have risk factors for such resistance. Fluoroquinolone properties include a broad spectrum of coverage, low rates of resistance, and good safety profiles.

The expanding role of fluoroquinolones.

There has been a growing rate of resistance among common urinary tract pathogens, such as Escherichia coli, to traditional antimicrobial therapies including the "gold standard" trimethoprim-sulfamethoxazole (TMP-SMX). Consequently, fluoroquinolone antimicrobial agents have taken on an expanding management role for UTIs. In fact, the recent Infectious Diseases Society of America clinical management guidelines for UTI recommend fluoroquinolones as first-line therapy for uncomplicated UTI in areas where resistance is likely to be of concern. Fluoroquinolones have demonstrated high bacteriologic and clinical cure rates, as well as low rates of resistance, among most common uropathogens. There are currently 7 fluoroquinolones with indications for UTI in the United States. However, only 3 are commonly used: levofloxacin, ciprofloxacin, and, to a lesser extent, gatifloxacin. Many of the fluoroquinolone agents have once-daily dosing regimens, enhancing patient adherence. In addition, levofloxacin and gatifloxacin have same-dose bioequivalency between their intravenous and oral formulations, allowing for "switch" or step-down therapy from parenteral to oral formulations of the same agent at the same dose. Fluoroquinolones are indicated for the management of acute uncomplicated UTIs, as well as complicated and severe UTI and pyelonephritis, in adults. They are the first-line treatment of acute uncomplicated cystitis in patients who cannot tolerate sulfonamides or TMP, who live in geographic areas with known resistance >10% to 20% to TMP-SMX, or who have risk factors for such resistance. Fluoroquinolone properties include a broad spectrum of coverage, low rates of resistance, and good safety profiles.

An international survey of the antimicrobial susceptibility of pathogens from uncomplicated urinary tract infections: the ECO.SENS Project.

The ECO.SENS study is the first international survey to investigate the prevalence and susceptibility of pathogens causing community-acquired acute uncomplicated urinary tract infections (UTIs). Midstream urine samples were taken for culture and for testing for the presence of leucocytes from 4734 women not older than 65 years presenting with symptoms of acute UTI at 252 community health care centres in 17 countries. Recognized urinary tract pathogens were identified and the susceptibility to 12 antimicrobials determined. Pathogens were present in 3278 (69.2%) patients, Escherichia coli accounting for 77.0% of isolates. In E. coli, 42% of the isolates were resistant to one or more of the 12 antimicrobial drugs investigated. Resistance was most common to ampicillin (29.8%) and sulfamethoxazole (29.1%), followed by trimethoprim (14.8%), trimethoprim/sulfamethoxazole (14.1%) and nalidixic acid (5.4%). Resistance in E. coli to co-amoxiclav, mecillinam, cefadroxil, nitrofurantoin, fosfomycin, gentamicin and ciprofloxacin was <3%. However, co-amoxiclav resistance was apparent in Portugal (9.3%) as was resistance to the quinolones, nalidixic acid and ciprofloxacin, in Portugal (11.6% and 5.8%, respectively) and Spain (26.7% and 14.7%, respectively). Overall, Proteus mirabilis were less resistant to ampicillin (16.1%) and more resistant to trimethoprim (25.5%) than E. coli, whereas Klebsiella spp. were more resistant to ampicillin (83.5%) and fosfomycin (56.7%). 'Other Enterobacteriaceae' were more resistant to the broad spectrum beta-lactams (ampicillin 45.9%, co-amoxiclav 21.3% and cefadroxil 24.6%), nitrofurantoin (40.2%) and fosfomycin (15.6%). In Staphylococcus saprophyticus resistance development was rare. Overall, antimicrobial resistance was lowest in the Nordic countries and Austria and highest in Portugal and Spain.

A UK multicentre study of the antimicrobial susceptibility of bacterial pathogens causing urinary tract infection.

To determine the prevalence of resistance amongst urinary tract pathogens against antimicrobials used to treat urinary tract infections (UTIs) in the UK to provide data to help direct empirical therapy. During 1999-2000, a total of 1291 bacterial isolates causing UTI were collected from 8 centres in the UK. Isolates were cultured from patients with (1). community-acquired UTI in those less than 65 years old (397), (2). hospital-acquired UTI other than those admitted with pyelonephritis (394), (3). pyelonephritis (108) and (4). community-acquired UTI in those greater than 65 years old (392). After re-identification, MICs for a range of antimicrobials were determined and interpreted using NCCLS procedures and interpretive guidelines. Escherichia coli was the predominant pathogen in all categories but the total percentage for each category varied (56.3-77.3%). The next three pathogens of importance were Enterococcus faecalis, Klebsiella pneumoniae and Proteus mirabilis which varied in prevalence slightly from category to category. The activity of amoxycillin against E. coli (51.3% susceptible) was greatly reduced as a result of beta-lactamase production and only partially restored by the addition of clavulanic acid (78.8% susceptible). Cefuroxime was very active against E. coli using parenteral form breakpoints (97.1% susceptible) but less so using oral form breakpoints (68.6% susceptible). Cefuroxime was inactive against Enterococcus spp. and Pseudomonas spp. Nitrofurantoin was very active against isolates of E. coli (96.3% susceptible) and E. faecalis but not against K. pneumoniae, P. mirabilis or Pseudomonas aeruginosa. Overall susceptibility to trimethoprim ranged from 58.1% to 84.5% for the most prevalent pathogens. Ciprofloxacin was highly active against the UTI pathogens examined in this study with susceptibilities of between 88.6% and 97.7% for the most prevalent pathogens (E. coli, n=864, 97.7% susceptible) and was the only oral agent tested with activity against Pseudomonas spp. These data provide much needed information on the prevalence of antimicrobial resistance amongst pathogens currently causing UTI in the UK.

Resistance Trends in Urinary Tract Pathogens and Impact on Management

The prevalence of antimicrobial resistance among urinary tract pathogens is reviewed and its clinical impact on management is determined.A Medline search supplemented with references quoted in bibliographies of articles on urinary tract infections, epidemiology of antimicrobial resistance among uropathogens and clinical outcomes in urinary tract infections was conducted.Although some geographic variation is noted in resistance rates among urinary tract Escherichia coli isolates, rates were highest for ampicillin (39% to 45%) and trimethoprim-sulfamethoxazole (14% to 31.4%) and lowest for nitrofurantoin (1.8% to 16%) and fluoroquinolones (0.7% to 10%). Resistance rates also varied based on patient age. A few studies suggested that antimicrobial resistance impacts clinical and bacteriological outcome but the results are limited by the small number of patients. A randomized trial in women with acute uncomplicated pyelonephritis indicated that those treated with trimethoprim-sulfamethoxazole had a clinical and bacteriological success rate that was significantly lower in those patients treated with this drug when the infecting organism was resistant compared to those in whom the organism was susceptible to trimethoprim-sulfamethoxazole.Resistance rates among common uropathogens continue to evolve and appear to be increasing to many commonly used agents. Continued surveillance of resistance rates among uropathogens is needed to ensure that appropriate recommendations can be made for treatment of infected patients. Further studies addressing the clinical and bacteriological outcomes of patients infected with a resistant pathogen are needed.

Resistance Trends in Urinary Tract Pathogens and Impact on Management

Resistance Trends in Urinary Tract Pathogens and Impact on Management

Comparison of three chromogenic agar plates for isolation and identification of urinary tract pathogens

Objective To comparatively assess the performance of three chromogenic agar plates, CPS ID2, Chromogenic UTI, and USA, for the detection and enumeration of all urinary tract pathogens and the direct identification of Escherichia coli, Proteus mirabilis and Enterococcus spp.Methods Two hundred and forty-three urine specimens prospectively collected from hospitalized patients were randomly inoculated in parallel on the three media.Results Of the 243 urine specimens, 235 yielded positive cultures, of which 151 were pure cultures and 84 were mixed cultures. CPS ID2, Chromogenic UTI and USA agar gave detection rates of 99.1%, 97.1% and 96.6%, respectively. The main difference in non-detection between CPS ID2 agar and the two new media concerned Staphylococcus spp. strains. Based on the total number of strains detected (n = 348), the total identification rates of E. coli, P. mirabilis and Enterococcus spp. on CPS ID2 agar, Chromogenic UTI agar and USA agar were 60.3%, 61.2% and 59.2%, respectively.Conclusion The detection rates and identification rates of the three media were very close and only minor differences were noted. The lower detection rates for Chromogenic UTI and USA were mainly due to their lesser ability to support growth of Staphylococcus spp.