The usefulness of screening tests for pyuria in combination with culture in the diagnosis of urinary tract infection

A prospective study was conducted to examine the usefulness of screening tests for pyuria in combination with culture in the diagnosis of urinary tract infection (UTI) in outpatients. Midstream urine specimens were collected from 340 patients seen in the emergency treatment center (ETC) and were examined for pyuria using the chamber count method and the Leukocyte Esterase Dipstick test (LE; Bio Dynamics, Indianapolis, IN). All specimens were cultured quantitatively using both 0.01 ml and 0.001 ml calibrated bacteriologic loops. A total of 100 UTIs, defined by combined clinical and laboratory critera, were identified. Sixty-four (64%) infections were identified by culture using the standard interpretive breakpoint of greater than or equal to 10(5) CFU/ml and an additional 36 (36%) were detected using the low-count interpretive breakpoint of greater than or equal to 10(3) CFU/ml. We found pyuria detection by either the chamber count method or the LE test to be extremely useful in directing subsequent culture efforts. By using either of the tests for pyuria to determine the significance of low-count bacteriuria (10(3) - less than 10(5) CFU/ml) we were able to achieve maximum sensitivity (92%-99%) and specificity (99.2-99.6%) for the diagnosis of UTI while minimizing the number of specimens in which low numbers of organisms must be evaluated.     

Detection of PCR products of the ipaH gene from Shigella and enteroinvasive Escherichia coli by enzyme linked immunosorbent assay

PCR techniques applied to diarrheal stools reliably diagnose Shigella and enteroinvasive Escherichia coli (EIEC) infections. Identification of PCR products using agarose gel electrophoresis (AGE) and hybridization with DNA probes has several shortcomings. Automated methods of identifying PCR products that process larger numbers of specimens can facilitate epidemiologic studies and standardize results. In this study, we used ELISA following PCR to detect ipaH gene sequences of Shigella and EIEC from 89 diarrheal stools. Results of ELISA were compared with AGE with and without DNA probe, and with culture. Two specimen preparation methods were compared as well: boiling/centrifugation, and purification with silicon dioxide (SiO(2)). Both PCR product-detection methods identified significantly more infections than did culture. PCR-ELISA detected significantly more infections than PCR-AGE when processed using SiO2 (P = 0.014). PCR-ELISA allows screening of larger numbers of specimens, automates test results, and avoids use of mutagenic reagents. PCR-ELISA is faster than PCR-AGE when testing large numbers of specimens, although not when testing small numbers of specimens.     

Diagnostic value of various urine tests in the Jordanian population with urinary tract infection.

We compared the performance of leukocyte esterase and nitrite reductase dipstick tests with microscopic examination and uroculture in cases with clinically suspected urinary tract infection (UTI). We studied urine specimens from 504 Jordanian patients which were obtained by the mid-stream clean catch method and analyzed for bacteria. All samples were subjected to culture. Results of urine dipstick tests and pyuria (white blood cells (WBC)/high power field) were compared with urine culture for each sample. Significant bacteriuria was found in 117 cases (23.2%) with positivity of 59% and 68.5% for the presence of nitrite reductase and leukocyte esterase, respectively. Echerichia coli was the most common organism isolated. The dipstick leukocyte esterase and nitrite testing had a sensitivity of 68.5% and 59% for detecting bacteriuria in UTI cases and specificity of 73.5% and 78%, respectively. The positive predictive value of the tests was 44% and 60%, and the negative predictive value 88.5% and 86.2%, respectively. Microscopic WBC showed 86.5% specificity but low sensitivity. Urine dipstick results and pyuria significantly correlated with the results of urine culture but demonstrated more false-positive results, which ranged from 13.4-26.6%. The probability of growing a urinary pathogen correlated with urinary WBC counts and allowed prediction of the presence or absence of bacteriuria by counting urinary leukocytes. A combination of pyuria and urine dipstick testing appears to be a very useful marker for the diagnosis of UTI. Urine culture can be omitted if both tests are negative.     

An observational study of empirical antibiotics for adult women with uncomplicated UTI in general practice

OBJECTIVES: Women presenting in primary care with symptoms suggestive of uncomplicated urinary tract infection (UTI) are commonly managed without urine culture. We therefore do not know how successful general practitioners (GPs) are at targeting antibiotic treatment to women who would have had a microbiologically confirmed UTI, or at avoiding antibiotics in those who would have had a negative culture, had all patients with a suspected UTI been sampled. We therefore explored the association between antibiotic prescribing and urine culture results when culture was performed in all symptomatic patients. METHODS: GPs in nine general practices in South Wales were asked to submit urine specimens from all women consulting with clinically suspected, uncomplicated UTI. Patients were followed up 2 weeks later by questionnaire. RESULTS AND CONCLUSIONS: One hundred and thirteen adult women with a median age of 54 years were included and 61% received empirical antibiotics. There was very low agreement between the decision to prescribe empirically and subsequent culture result (Kappa = 0.04), with 60% of those prescribed empirical antibiotics subsequently found to have a negative culture, and 25% of those found to have a positive culture not prescribed empirical antibiotics. Current strategies to target empirical antibiotic prescribing in clinically suspected, uncomplicated UTI require review.     

Analysis of cross infection using genomic fingerprinting in nosocomial urinary tract infection caused by Enterococcus faecalis

To evaluate cross infection and a possible outbreak of Enterococcus faecalis urinary tract infection (UTI) in our urology ward, we studied the DNA fingerprinting of E. faecalis strains isolated from nosocomial UTI patients, in the period 1982–1996, using arbitrarily primed polymerase chain reaction (AP-PCR) analysis. The serovar and amplified products of DNA extracted from clinically isolated urinary E. faecalis strains by the AP-PCR method were analyzed, and the respective isolation periods of E. faecalis-positive UTI patients were investigated. There were nine patients with E. faecalis UTI between March and May 1994 and all strains isolated from their urine specimens were serovar type 7. AP-PCR revealed that five of the nine isolates had the same pattern. It appeared that these strains had caused the outbreak of E. faecalis UTI. Cross-infection between patients with E. faecalis UTI was demonstrated by genomic fingerprinting, suggesting that cross infection had occurred via urinary catheters or by hand contact in our ward. We may, therefore, reasonably conclude that we should beware of the transmission of urinary E. faecalis and take countermeasures against its dissemination. Received: April 8, 1998 / Accepted: October 14, 1998     

Risk factors for ciprofloxacin resistance among Escherichia coli strains isolated from community-acquired urinary tract infections in Turkey

OBJECTIVES: To determine the risk factors for community-acquired ciprofloxacin-resistant Escherichia coli urinary tract infection (UTI). METHODS: The study was performed with isolates from community-acquired UTIs collected from 15 centres representing six different geographic regions of Turkey. All microbiological procedures were carried out in a central laboratory. Multivariate analysis was performed for detection of risk factors for resistance. Use of quinolones more than once within the last year, living in a rural area, having a urinary catheter, age >50 and complicated infections were included in the model as variables and logistic regression was performed. RESULTS: A total of 611 gram-negative isolates were studied: 321 were isolated from uncomplicated UTI and 290 were isolated from complicated UTI. E. coli was the causative agent in 90% of the uncomplicated UTIs and in 78% of the complicated UTIs (P < 0.001). Seventeen percent of E. coli strains isolated from uncomplicated cases and 38% of E. coli strains isolated from complicated UTI were found to be resistant to ciprofloxacin. In multivariate analysis, age over 50 [odds ratio (OR): 1.6; confidence interval (CI): 1.08-2.47; P = 0.020], ciprofloxacin use more than once in the last year (OR: 2.8; CI: 1.38-5.47; P = 0.004) and the presence of complicated UTI (OR: 2.4; CI: 1.54-3.61; P < 0.001) were found to be associated with ciprofloxacin resistance. Detection of strains of E. coli producing extended-spectrum beta-lactamase (ESBL) enzymes was two times more common in the patients who received ciprofloxacin than those who did not (15% versus 7.4%). CONCLUSIONS: The increasing prevalence of infections caused by antibiotic-resistant bacteria makes the empirical treatment of UTIs more difficult. One of the important factors contributing to these high resistance rates might be high antibiotic use. Urine culture and antimicrobial susceptibility testing are essential in Turkey for patients with UTI who have risk factors for resistance, such as previous ciprofloxacin use. Fluoroquinolone-sparing agents such as nitrofurantoin and fosfomycin should be evaluated as alternative therapies by further clinical efficacy and safety studies.     

泌尿道感染大肠埃希菌耐药性及其相关性分析

目的:分析泌尿道感染(UTI)大肠埃希菌(E.coli)临床分离株的耐药性及其相关性,为其感染的经验性治疗提供科学依据。方法:收集UTI患者E.coli分离株,采用Kirby-Bauer法进行药敏试验。用WHONET 5.3软件和SAS6.0软件进行有关统计分析。结果:E.coli对环丙沙星、头孢噻肟等多种抗菌药物的耐药率不断上升,对不同类抗菌药物耐药间存在着广泛而显著的正相关。结论:对多类抗菌药物耐药的正相关与不合理用药是E.coli耐药性迅速增高的重要原因。临床医生在经验性选药时应综合考虑病原菌的耐药性及其相关性。     

The Prevalence of Urinary Tract Infections and Sexually Transmitted Disease in Women with Symptoms of a Simple Urinary Tract Infection Stratified by Low Colony Count Criteria

OBJECTIVES: Urinary tract infections (UTIs) and early pelvic infections due to sexually transmitted disease (STD) may cause similar symptoms. Therefore, a simple history and urine dip to establish a diagnosis of UTI may result in overtreatment of UTIs and undertreatment of STDs. The objective of this study was to determine the proportion of women with symptoms suggestive of a UTI who are urine culture positive versus urine culture negative, the prevalence of STDs between groups, and if elements of the history or examination may predict those requiring STD screening. METHODS: This was a prospective cohort study in an urban emergency department. Women 18-55 years of age with urinary frequency, urgency, dysuria, and no new vaginal discharge or change in discharge were enrolled. The following were performed: detailed history; bladder catheterization for urinalysis, urine dip, and urine culture; pelvic examination and cervical samples for gonorrhea and Chlamydia trachomatis DNA ligase; and wet mount examinations. Main outcome measurements were the percentage of women who were urine culture positive (using low count criteria of 10(2) colony-forming units [CFU]/mL), the proportion of STDs between urine culture groups, and univariate analysis and logistic regression of historical and examination elements. RESULTS: Ninety-two patients were enrolled; the mean age was 26 years (range, 18-51 years). All had samples for DNA ligase (one quantity not sufficient) and urinalysis or urine dip, while 75 of 92 had urine cultures performed. A total of 57.3% (43/75) were urine culture positive at 10(2) CFU/mL, while the STD rate for those with urine cultures was 17.3% (13/75). There was no statistically significant difference in the number of STDs between urine culture positive and urine culture negative groups. The only variable on logistic regression predictive of an STD (based on all 91 patients) was more than one sex partner in the past year (p = 0.013). No other element of the history or pelvic examination helped differentiate those who tested positive for an STD. CONCLUSIONS: A total of 17.3% of women with symptoms of a UTI in this study had an STD, while only 57.3% were urine culture positive by catheterization using low count criteria. The proportion of STDs between those with and without a UTI was not significantly different.     

UF-1000i全自动尿有形成分分析仪对尿路感染的诊断价值

目的 研究UF-1000i尿有形成分分析仪对诊断尿路感染的价值.方法 采用UF-1000i尿有形成分分析仪检测150份临床尿液标本的白细胞、酵母样真菌及细菌计数,将这3项检测结果结合起来判断是否具有尿路感染(UTI)信息,并记录下具有UTI信息标本的散点图.同时将尿标本进行细菌培养和鉴定,将UF-1000i尿有形成分分析仪的检测结果与之做比较分析.以临床诊断尿路感染的标准作为诊断UTI的金标准,计算UF-1000i尿有形成分分析仪对诊断UTI的敏感度、特异度等评估参数,以及细菌散点图分布与尿细菌培养结果、临床诊断的符合情况.结果 通过对146份标本的比较分析,UF-1000i尿有形成分分析仪阳性检出率为32.9%(48/146),细菌培养阳性检出率为28.8%(42/146),2种检测方法之间差异无统计学意义(χ2=1.79,P0.05),且一致性较好(Kappa=0.775 6).UF-1000i尿有形成分分析仪判断筛选UTI信息的敏感度为76.0%(38/50),特异度为89.6%(86/96),阳性预测值为79.2%(38/48),阴性预测值为87.8%(86/98);UF-1000i尿有形成分分析仪测得细菌的球杆菌分布与细菌培养结果基本一致.结论 UF-1000i尿有形成分分析仪的"YTU信息"研究参数对诊断尿路感染具有重要价值.     

1386例小儿中段尿培养病原菌分布及耐药性分析

目的分析小儿中段尿培养病原菌的分布及耐药性,以期对儿童临床泌尿系统感染的临床诊疗和预防控制提供有力理论支持。方法对2010～2011年1 386例小儿中段尿培养的病原菌,采用法国生物梅里埃(BioMerieux)VITEK-32全自动微生物分析系统进行鉴定。采用K-B纸片法对病原菌进行常用抗生素的敏感性检测。使用WHONET 5.4软件对原始数据进行分析和统计学处理。结果 2010～2011年尿培养标本1 386例共分离到病原菌138株,阳性率为9.96%。其中革兰阴性菌96株,占69.57%,居前2位的是大肠埃希菌、肺炎克雷伯菌;革兰阳性菌34株,占24.64%,居前2位的是屎肠球菌和粪肠球菌;真菌8株,占5.8%。2年间共分离出大肠埃希菌88株,其中产超广谱β-内酰胺酶菌株56株,比例高达63.64%。结论小儿中段尿培养的病原菌仍以大肠埃希菌为主,泌尿系统感染治疗形势由于细菌多重耐药和交叉耐药日趋严峻,日常了解并监测病原菌分布特点及其耐药情况对临床合理选用抗生素具有重要意义。     

老年精神疾病患者尿路感染病原菌及耐药性和产超广谱β-内酰胺酶状况分析

目的了解老年精神疾病患者泌尿系感染病原菌分类及耐药性特点,为临床合理用药提供依据。方法对本院2009～2010年200例老年精神病合并泌尿系统感染患者尿培养及药敏结果进行回顾性分析。结果共分离致病菌200例,以大肠埃希菌、奇异变形杆菌为主(66.5%),产超广谱β-内酰胺酶(ESBLs)的大肠埃希菌和肺炎克雷伯菌的检出率分别为47.6%、40.0%。尿路感染患者对常用抗菌药都产生了一定的耐药性。结论老年精神疾病患者尿路感染比较高,耐药性增强,应加强监测和控制。     

Real-time quantitative PCR for the detection of Streptococcus pneumoniae in the middle ear fluid of children with acute otitis media

PCR based on the amplification of pneumolysin gene fragments has previously been applied to demonstrate Streptococcus pneumoniae in clinical specimens. Here, a real-time PCR method for the detection and quantification of pneumococci by amplifying a 206-bp fragment of the pneumolysin-encoding gene is described. The amplified fragments were detected simultaneously using fluorescent-labeled sequence-specific hybridization probes. The applicability of the assay to clinical samples was evaluated by studying 50 middle ear fluid (MEF) specimens from children with acute otitis media. Twenty-six of the MEF samples were positive by real-time PCR and the numbers of genome equivalents detected varied from 90 to 88,000/microl in 17 culture-positive samples and from 1 to 1,200/microl in 9 culture-negative samples. The results were compared to culture findings and to results obtained by using agarose gel electrophoresis or Europium-labeled hybridization probes for the detection of amplification products of conventional PCR. The sensitivity and specificity of the real-time PCR assay developed in the present study compared to culture were 100 and 73%, and to conventional PCR with agarose gel and/or TRF detection 93 and 96%, respectively. The real-time PCR assay was found to be rapid, easy to use, and sensitive in detecting and quantifying pneumococci.     

老年尿路感染产超广谱β-内酰胺酶大肠埃希菌耐药性分析

目的探讨老年尿路感染患者中产超广谱β-内酰胺酶（ESBLs）大肠埃希菌的耐药性。方法回顾性分析2008年至2009年117例ESBLs（＋）老年尿路感染患者中段尿标本结果。结果大肠埃希菌产ESBLs率自2008年的49.1%上升到2009年的53.9%。产ESBLs大肠埃希菌对氨基糖苷类,二、三代头孢菌素以及酶抑制剂抗生素的耐药性呈上升趋势。产ESBLs大肠埃希菌对第二、三代头孢菌素,氨苄西林,环丙沙星耐药率高,对头孢哌酮舒巴坦、丁胺卡那敏感,对碳青酶类无耐药。结论老年尿路感染患者中产ESBLs大肠埃希菌检出率和耐药性非常高,头孢哌酮舒巴坦是此类患者较为理想的选择。     

The etiology of urinary tract infection: traditional and emerging pathogens

The microbial etiology of urinary infections has been regarded as well established and reasonably consistent. Escherichia coli remains the predominant uropathogen (80%) isolated in acute community-acquired uncomplicated infections, followed by Staphylococcus saprophyticus (10% to 15%). Klebsiella, Enterobacter, and Proteus species, and enterococci infrequently cause uncomplicated cystitis and pyelonephritis.The pathogens traditionally associated with UTI are changing many of their features, particularly because of antimicrobial resistance. The etiology of UTI is also affected by underlying host factors that complicate UTI, such as age, diabetes, spinal cord injury, or catheterization. Consequently, complicated UTI has a more diverse etiology than uncomplicated UTI, and organisms that rarely cause disease in healthy patients can cause significant disease in hosts with anatomic, metabolic, or immunologic underlying disease. The majority of community-acquired symptomatic UTIs in elderly women are caused by E coli. However, gram-positive organisms are common, and polymicrobial infections account for up to 1 in 3 infections in the elderly. In comparison, the most common organisms isolated in children with uncomplicated UTI are Enterobacteriaceae. Etiologic pathogens associated with UTI among patients with diabetes include Klebsiella spp., Group B streptococci, and Enterococcus spp., as well as E coli. Patients with spinal cord injuries commonly have E coli infections. Other common uropathogens include Pseudomonas and Proteus mirabilis.Recent advances in molecular biology may facilitate the identification of new etiologic agents for UTI. The need for accurate and updated population surveillance data is apparent, particularly in light of concerns regarding antimicrobial resistance. This information will directly affect selection of empiric therapy for UTI.     

Uncomplicated urinary tract infections. Bacterial findings and efficacy of empirical antibacterial treatment

OBJECTIVE: To assess bacterial aetiology, antimicrobial susceptibility and efficacy of empirical treatment in uncomplicated urinary tract infections and to evaluate the dipstick as a diagnostic tool. DESIGN: Prospective study. SETTING: Clinical microbiology laboratory and 17 general practice clinics in Telemark County, Norway. SUBJECTS: A total of 184 female patients between 15 and 65 years of age with symptoms of uncomplicated urinary tract infection. MAIN OUTCOME MEASURES: Results from dipstick testing (leucocyte esterase and nitrite), bacterial culture, susceptibility patterns and efficacy of empirical antibacterial therapy on symptoms. RESULTS: Significant bacteruria was detected in 140 (76%) of the 184 urines. The leukocyte esterase test was of little help in predicting culture-positive UTI. A positive nitrite test accurately predicted culture-positivity, while a negative result was ambiguous. The most common bacterium, E. coli, was found in 112 (80%) of the 140 positive urines and was predominantly sensitive to ciprofloxacin (100%), mecillinam (94%), nitrofurantoin (97%), trimethoprim (88%), and sulphonamide (81%), and to a lesser extent to ampicillin (72%). In 18 patients the causative bacterium was resistant to the therapeutic agent used; 7 of these returned to their GP with persisting symptoms while in 11 symptoms resolved without further treatment. CONCLUSION: The study confirms E. coli as the predominant cause of uncomplicated UTI. Since in the majority of cases the bacterium found was susceptible to the locally preferred antimicrobials and the patients' symptoms were cured, empiric therapy is found to be an effective practice in the study area and, by inference, in others with similar antimicrobial susceptibility patterns.     

Development of a long-term ascending urinary tract infection mouse model for antibiotic treatment studies

A model of ascending unobstructed urinary tract infection (UTI) in mice was developed to study the significance of the antibiotic concentration in urine, serum, and kidney tissue for efficacy of treatment of UTI in general and pyelonephritis in particular. Outbred Ssc-CF1 female mice were used throughout the study, and Escherichia coli was used as the pathogen. The virulence of 11 uropathogenic E. coli isolates and 1 nonpathogenic laboratory E. coli strain was examined. Strain C175-94 achieved the highest counts in the kidneys, and this strain was subsequently used as the infecting organism. The model gave reproducible bladder infections, i.e., bacteria were recovered from 22 of 23 control mice after 3 days, and histological examination of kidney tissue showed that of 14 infected kidneys, 7 (50%) showed major histological changes, whereas 3 of 36 uninfected kidneys showed major histological changes (P = 0.018). Once the model was established, the efficacies of different doses of cefuroxime and gentamicin, corresponding to active concentrations in urine only or in urine, serum, and kidney tissue simultaneously, were examined. All cefuroxime doses resulted in significantly lower counts in urine than control treatments, but the dose which produced concentrations of cefuroxime only in urine and not in serum or kidney tissue had no effect on kidney infection. Even low doses of gentamicin (0.05 mg/mouse) resulted in concentrations in renal tissue for prolonged times due to accumulation. All gentamicin doses had a significant effect (compared to the effect of the control treatment) on bacterial counts in urine and kidneys. The antibiotic effect on bacterial counts in bladders was negligible for unknown reasons. Use of the mouse UTI model is feasible for study of the effect of an antibiotic in the urinary system, although the missing antibacterial effect in the bladder needs further evaluation.     

Antibacterial activity of urine after administration of ofloxacin for 5 days

The antibacterial activity of ofloxacin was evaluated in urine over a period of 96 h after oral administration for 5 days of 200 mg twice a day in 12 healthy female volunteers. Bacteriostatic and bactericidal activity of urines were studied for five strains of enterobacterias recovered from urinary infections: two strains of Escherichia Coli Nal-S and Nal-R, two strains of Proteus mirabilis Nal-S and Nal-R, and one strain of Klebsiella pneumoniae Nal-S. Mean urinary concentrations of ofloxacin were very high during the first 12 h following last intake. They were still above 7 mg/l till the 48th hour and above 1.6 mg/l till the 72nd hour. Bactericidal activity of urine was present for 72 h in respect of four strains studied at that time; urine was not bactericidal as regards E. coli Nal-R. After 5 days of oral treatment with ofloxacin (200 mg b.i.d.), urine retains a bactericidal activity for at least 72 h against bacterial strains of urinary tract infections.     

中段尿细菌培养的临床应用研究

目的探讨规范留取中段尿对尿液培养结果的重要性，男性和女性患者泌尿道感染主要致病菌的分布差异及细菌对抗生素耐药情况。方法收集佛山市中医院近一年住院和门诊病人作中段尿细菌培养病例。细菌鉴定采用法国生物梅里埃公司VTTEK—AMS细菌鉴定系统，药敏采用琼脂纸片扩散（K—B）法，调查研究住院和门诊病人采样程序；分别统计住院病人和门诊病人中段尿培养合格率、阳性结果及主要致病菌；主要致病菌的耐药情况分析。结果住院和门诊病人留取中段尿检出率分别为67％和23％。女性患者略多于男性患者。男女尿路感染均以革兰阴性杆菌为主，优势菌株均为大肠埃希菌，分别占21．83％和46.21％；感染的革兰阳性菌以肠球菌为主，以粪肠球菌和屎肠球菌最常见；真菌所占的比例亦较高，主要为白假丝酵母菌和热带假丝酵母菌；革兰阴性杆菌对甲氧苄啶、氨苄西林、庆大霉素、环丙沙星、头孢类耐药率高；革兰阳性球菌对四环素、利福平、青霉素、左氧氟沙星、环丙沙星、红霉素耐药率高；真菌对本院所选的六种药物均较敏感。结论中段尿培养应规范留取中段尿，提高标本合格率。泌尿系统感染女性略多于男性，主要痛原菌为革兰阴性杆菌，其中以大肠埃希菌为主。致病菌对多种药物耐药，临床应参照药敏结果合理用药。     

Species and antimicrobial resistance of uropathogens isolated from patients with urinary catheter

A large number of hospitalized patients have an indwelling urinary tract catheter (IUC) placed at some time during their hospital stay and may suffer from catheter-associated urinary tract infections, the leading cause of nosocomial infections. Here we investigated the prevalence of uropathogens associated with catheter-associated urinary tract infections and assessed the resistances of these pathogens to commonly prescribed antibiotics. In total, 2,997 urine samples were examined at a regional hospital in Taipei, Taiwan in 2004: 1,948 (65%) samples from hospitalized patients and 1,049 (35%) samples from outpatients. Patients with IUCs accounted for 1,381 samples (46%). Stratified analyses were used to calculate the age- and gender-adjusted odds ratio (OR) of antimicrobial resistance associated with the use of IUCs. Compared to the urine specimens of the patients without IUCs, those isolated from catheterized patients had a lower prevalence rate of Escherichia (E.) coli (23.4% vs 36.8%) and higher rates of resistant strains including Pseudomonas species (16.4% vs 8.6%) and rare gram-negative bacilli (5.8% vs 4.5%). Additionally, IUCs significantly increased the antimicrobial resistance of E. coli (OR 2.41-3.07), other species of Enterobacteriaceae (OR 1.57-2.38), and rare gram-negative bacilli (OR 2.41-5.21) to nearly all antibiotics tested, such as trimethoprim/sulfamethoxazole. Thus, IUCs increased the prevalence of urinary tract infections caused by some highly resistant pathogens. Moreover, IUCs were associated with the increased risk of concurrent resistance of Enterobacteriaceae. Clinicians are advised to exercise better management of urinary catheter in order to further reduce and control catheter-associated urinary tract infections in hospitals.     

Detection of Escherichia coli O157 using equal-length double-stranded fluorescence probe in a real-time polymerase chain reaction assay

BACKGROUND: Enterohemorrhagic Escherichia coli (E. coli) O157 is a dangerous pathogen, which causes bloody diarrhea and severe hemolytic uremic syndrome (HUS). Although several assay systems based on real-time polymerase chain reaction (PCR) have been integrated to detect this pathogen, most of them are not specific. We report a real-time quantitative PCR method targeting rfbE, a gene specifically expressed in E. coli O157. This method can therefore be used to diagnose enterohemorrhagic Escherichia coli (E. coli) O157. METHODS: A nucleic acid based diagnostic assay system, combining equal-length double-stranded fluorescence probe technique and real-time PCR, was developed to detect E. coli O157. This assay system take advantage of the highly conserved rfbE O-antigen synthesis gene, and a pair of fluorescence-quenching probes complementary to rfbE gene were used in a real-time PCR to quantify the presence of the pathogen. RESULTS: The specificity of the diagnostic method was assessed by comparing test results on 14 different related pathogens including common E. coli, enteroinvasive Escherichia coli (EIEC), Salmonella, Shigella and E. coli O157. The detection limit of the method was determined using 10-fold serial dilutions of an E. coli O157 standard sample, and as few as 1.49 x 10(3) CFU/ml could be detected. All E. coli with serotype O157, which expresses rfbE gene, were positive in this assay, while all other species without rfbE gene expression were negative. CONCLUSIONS: By combining equal-length double-stranded fluorescence probe technique and real-time PCR, we have developed a simple, rapid, specific and sensitive method to detect E. coli O157.