METHOD FOR THE DETECTION OF SIGNIFICANT BACTERIURIA IN LARGE GROUPS OF PATIENTS

An Intact Cell Bioluminescence-Based Assay for the Simple and Rapid Diagnosis of Urinary Tract Infection

Urinary tract infection (UTI) is one of the most common infections, accounting for a substantial portion of outpatient hospital and clinic visits. Standard diagnosis of UTI by culture and sensitivity can take at least 48 h, and improper diagnosis can lead to an increase in antibiotic resistance following therapy. To address these shortcomings, rapid bioluminescence assays were developed and evaluated for the detection of UTI using intact, viable cells of Photobacterium mandapamensis USTCMS 1132 or previously lyophilized cells of Photobacterium leiognathi ATCC 33981™. Two platform technologies-tube bioluminescence extinction technology urine (TuBETUr) and cellphone-based UTI bioluminescence extinction technology (CUBET)-were developed and standardized using artificial urine to detect four commonly isolated UTI pathogens-namely, Escherichia coli, Proteus mirabilis, Staphylococcus aureus, and Candida albicans. Besides detection, these assays could also provide information regarding pathogen concentration/level, helping guide treatment decisions. These technologies were able to detect microbes associated with UTI at less than 105 CFU/mL, which is usually the lower cut-off limit for a positive UTI diagnosis. Among the 29 positive UTI samples yielding 105-106 CFU/mL pathogen concentrations, a total of 29 urine specimens were correctly detected by TuBETUr as UTI-positive based on an 1119 s detection window. Similarly, the rapid CUBET method was able to discriminate UTIs from normal samples with high confidence (p ≤ 0.0001), using single-pot conditions and cell phone-based monitoring. These technologies could potentially address the need for point-of-care UTI detection while reducing the possibility of antibiotic resistance associated with misdiagnosed cases of urinary tract infections, especially in low-resource environments.

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

BACKGROUND

It is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment.

OBJECTIVES

To develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness.

DESIGN

Multicentre, prospective diagnostic cohort study.

SETTING AND PARTICIPANTS

Children < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms.

METHODS

One hundred and seven clinical characteristics (index tests) were recorded from the child's past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood ('clinical diagnosis') and urine sampling and treatment intentions ('clinical judgement') were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 10(5) colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the 'clinician diagnosis' AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with 'clinical judgement'.

RESULTS

A total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, 'clinical diagnosis' correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. 'Clinical diagnosis' correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut.

CONCLUSIONS

Clinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparison of microbiological diagnosis of urinary tract infection in young children by routine health service laboratories and a research laboratory: Diagnostic cohort study

OBJECTIVES

To compare the validity of diagnosis of urinary tract infection (UTI) through urine culture between samples processed in routine health service laboratories and those processed in a research laboratory.

POPULATION AND METHODS

We conducted a prospective diagnostic cohort study in 4808 acutely ill children aged <5 years attending UK primary health care. UTI, defined as pure/predominant growth ≥105 CFU/mL of a uropathogen (the reference standard), was diagnosed at routine health service laboratories and a central research laboratory by culture of urine samples. We calculated areas under the receiver-operator curve (AUC) for UTI predicted by pre-specified symptoms, signs and dipstick test results (the "index test"), separately according to whether samples were obtained by clean catch or nappy (diaper) pads.

RESULTS

251 (5.2%) and 88 (1.8%) children were classified as UTI positive by health service and research laboratories respectively. Agreement between laboratories was moderate (kappa = 0.36; 95% confidence interval [CI] 0.29, 0.43), and better for clean catch (0.54; 0.45, 0.63) than nappy pad samples (0.20; 0.12, 0.28). In clean catch samples, the AUC was lower for health service laboratories (AUC = 0.75; 95% CI 0.69, 0.80) than the research laboratory (0.86; 0.79, 0.92). Values of AUC were lower in nappy pad samples (0.65 [0.61, 0.70] and 0.79 [0.70, 0.88] for health service and research laboratory positivity, respectively) than clean catch samples.

CONCLUSIONS

The agreement of microbiological diagnosis of UTI comparing routine health service laboratories with a research laboratory was moderate for clean catch samples and poor for nappy pad samples and reliability is lower for nappy pad than for clean catch samples. Positive results from the research laboratory appear more likely to reflect real UTIs than those from routine health service laboratories, many of which (particularly from nappy pad samples) could be due to contamination. Health service laboratories should consider adopting procedures used in the research laboratory for paediatric urine samples. Primary care clinicians should try to obtain clean catch samples, even in very young children.

Cephazolin Sodium—An In Vivo and In Vitro Evaluation of 100 Patients with Urinary Tract Infections

A random group of 100 patients in a general hospital were treated with cephazolin sodium for proven urinary tract infections. Sixty-six per cent had conditions predisposing to urinary tract infection. Under these somewhat difficult conditions the original infecting organism remained absent from the urine of 75 per cent of the 70 patients followed in the 3rd to 6th week period. This compares very favourably with response to other antimicrobial agents currently used in urinary tract infections.

Diminution of 2,3,5-triphenyltetrazolium chloride toxicity on Listeria monocytogenes growth by iron source addition to the culture medium

Tetrazolium salts (TTZ) such as 2,3,5-triphenyltetrazolium chloride (TTC) are readily reduced by bacterial populations of various genus. The reduced form of these redox indicators is conspicuously colored allowing a quick and easy detection of growth. The studies are mainly confined to Gram negative bacteria because of an important toxic effect of tetrazolium salts on Gram positive bacteria. Indeed, we observed an important impact of different tetrazolium salts on Listeria monocytogenes growth, curiously limited to an increase in the duration of the lag phase. In this study, we demonstrate that increasing the iron concentration in a medium containing TTC leads to a significant decrease of the lag phase. L. monocytogenes growth was kinetically measured and growth parameters were estimated using the Baranyi model. While lag phase diminution was found to be iron concentration dependent, growth rate was not affected. Addition of iron enables growth of some strains totally inhibited by a 0.4 g/l of TTC and for the other a significant reduction of the latency is observed. The nature of the mechanism resulting in a decrease of the observed lag phase remains unclear. Then, the use of iron supplementation may be proposed to overcome the inhibitory effect of TTC on L. monocytogenes.

The impact of antibiotic use on the incidence and resistance pattern of extended-spectrum beta-lactamase-producing bacteria in primary and secondary healthcare settings

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• The emergence and spread of bacteria producing extended-spectrum beta-lactamases (ESBLs) has important therapeutic and epidemiologic implications. • A key target for the establishment of hospital antibiotic stewardship is reducing the occurrence of additional antibiotic resistance. • Further research is needed to accumulate supporting evidence that reducing antibiotic use will result in a parallel reduction in antibiotic resistance.

WHAT THIS STUDY ADDS

• Fluoroquinolone restriction reversed ciprofloxacin resistance in primary and secondary healthcare settings. • Fluoroquinolone restriction reduced ESBL-producing bacteria incidence rates in both the primary and secondary healthcare settings. • This study highlights the value of time-series analysis in designing efficient antibiotic stewardship.

AIMS

The objective of the present study was to study the relationship between hospital antibiotic use, community antibiotic use and the incidence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in hospitals, while assessing the impact of a fluoroquinolone restriction policy on ESBL-producing bacteria incidence rates.

METHODS

The study was retrospective and ecological in design. A multivariate autoregressive integrated moving average (ARIMA) model was built to relate antibiotic use to ESB-producing bacteria incidence rates and resistance patterns over a 5 year period (January 2005-December 2009).

RESULTS

Analysis showed that the hospital incidence of ESBLs had a positive relationship with the use of fluoroquinolones in the hospital (coefficient = 0.174, P= 0.02), amoxicillin-clavulanic acid in the community (coefficient = 1.03, P= 0.03) and mean co-morbidity scores for hospitalized patients (coefficient = 2.15, P= 0.03) with various time lags. The fluoroquinolone restriction policy was implemented successfully with the mean use of fluoroquinolones (mainly ciprofloxacin) being reduced from 133 to 17 defined daily doses (DDDs)/1000 bed days (P < 0.001) and from 0.65 to 0.54 DDDs/1000 inhabitants/day (P= 0.0007), in both the hospital and its surrounding community, respectively. This was associated with an improved ciprofloxacin susceptibility in both settings [ciprofloxacin susceptibility being improved from 16% to 28% in the community (P < 0.001)] and with a statistically significant reduction in ESBL-producing bacteria incidence rates.

DISCUSSION

This study supports the value of restricting the use of certain antimicrobial classes to control ESBL, and demonstrates the feasibility of reversing resistance patterns post successful antibiotic restriction. The study also highlights the potential value of the time-series analysis in designing efficient antibiotic stewardship.

Evaluation of the IRIS 939 UDx flow microscope as a screening system for urinary tract infection

AIMS

To evaluate the IRIS flow microscope for the examination of urine specimens and to compare its performance with that of manual methods; in addition, to assess its usefulness as a screening system for the detection of significant bacteriuria in a routine clinical laboratory.

METHODS

The IRIS system was compared with manual quantitative microscopy for the detection of formed elements and with a variety of culture methods to detect urinary tract infection.

RESULTS

The IRIS had a higher sensitivity for the detection of clinically significant formed elements than did manual methods, and using a combination of bacterial and white cell counts produced a sensitivity and specificity of 94.9% and 54.4%, respectively, for predicting positive significant growth, with a 98.5% predictive value for a negative result. Approximately 50% of specimens could be reported as negative on the day of receipt using the screening algorithm.

CONCLUSIONS

The sensitivity and specificity of the IRIS is equivalent to that of other automated screening systems and would remove the need for manual microscopy for most specimens. The system was easy to operate and is a useful addition to the methods currently available for the examination of urine specimens.

A comparison of the performance of cystine lactose electrolyte deficient (CLED) agar with Oxoid chromogenic urinary tract infection (CUTI) medium for the isolation and presumptive identification of organisms from urine

AIMS

As part of the UK antimicrobial resistance strategy and action plan, the Public Health Laboratory Service (PHLS) is required to collect antibiotic susceptibility data so that resistance trends and patterns can be monitored. Most laboratories report urine Gram negative isolates, as "coliforms" according to morphological appearance, but without an acceptable identification system the antimicrobial surveillance data will be meaningless. Commercially available identification systems tend to be expensive and time consuming. Chromogenic agars, which claim to improve the detection of mixed cultures and identification of organisms from urine, have now become available and may provide a cost effective alternative. The primary aim of this study was to compare the performance of cystine lactose electrolyte deficient (CLED) agar with a chromogenic agar (Oxoid urinary tract infection medium; CUTI) in terms of isolation rates and ability to detect mixed cultures. Secondary aims were to evaluate the correlation of "presumptive" identification of isolates from chromogenic media with that of two commercial identification systems and to appraise the sensitivity of the semiquantitative loop and filter paper strip culture techniques.

METHOD

One thousand, four hundred and sixty six urine samples were examined in four laboratories using the semiquantitative culture methods of 1 microl loop and filter paper strip. The degree of accuracy of organism identification was measured by comparing the presumptive identification using colony colour supplemented with simple bench tests, with identification obtained from two more complex commercial systems.

RESULTS

There was no significant difference between the performance of the loop and filter paper strip methods on the CLED agar, but the CUTI agar performed significantly better than the CLED agar for the detection of significant isolates and mixed cultures. This difference was greater using the loop method. Identification of the organisms using the commercial systems gave > 99% agreement and was therefore considered suitable as a standard against which to compare the presumptive CUTI identification. Using the manufacturer's colony colour criteria in combination with a bench indole test, the CUTI medium was 99% specific for Escherichia coli, although this was reduced to 97% if the indole test was omitted. Citrobacter spp were the most commonly misidentified organisms, giving false presumptive identification as E coli. By testing oxidase activity to differentiate Pseudomonas spp and the absence of indole production to support the identification of Proteus mirabilis, the CUTI medium provided a suitable identification for 86.8% of Gram negative isolates. The remaining 13.2% would require further identification.

CONCLUSION

CUTI medium improves the detection of mixed cultures, thereby improving the reliability of reporting of significant isolates when compared with CLED agar. When supplemented with simple bench tests it provides an identification system capable of speciating 86.8% of Gram negative isolates and providing a valuable cost effective mechanism for antimicrobial resistance surveillance.

ACP Best Practice No 167: the laboratory diagnosis of urinary tract infection

Urinary tract infection is common, and it is not surprising that urine specimens make up a large proportion of those samples submitted to the routine diagnostic laboratory. Many of these specimens will show no evidence of infection and several methods can be used to screen out negative samples. Those that grow bacteria need to be carefully assessed to quantify the degree of bacteriuria and hence clinical relevance. To influence treatment, a final report should be produced within 24 hours of specimen receipt, with turnaround times continuously monitored. Much work needs to be done to determine the cost effectiveness involved in processing urine specimens and the evidence base for the final report provided.

The use of CHROMagar Orientation as a primary isolation medium with presumptive identification for the routine screening of urine specimens

The aim of the study was to compare the use of a novel differential culture medium CHROMagar, for both primary isolation and presumptive identificaton, with the method currently used in our laboratory for screening mid-stream-urine samples (MSU). Routine methods (RM) included blotting paper imprinting of all specimens and additional quantitative culture on cysteine lactose electrolyte-deficient agar (CLED) for selected samples together with Microbact 12E for further identification. The CHROMagar method (CH) relied on the use of blotting paper imprints, colonial colour and morphology on CHROMagar only. With respect to the 3390 MSU specimens examined, both methods yielded similar results in 3240, including > or = 87% of Escherichia coli, Pseudomonas spp., Staphylococcus spp., Proteus mirabilis/Morganella morganii and Enterobacter/Serratia/Klebsiella/Citrobacter spp. Of the 52 discordant identifications, yeasts were reported as staphylococci on CHROMagar in 10. The overall cost of materials per specimen was US$ 0.30 by RM and $ 0.24 by CH. It took about 3 min to perform each Microbact test. Thus, CHROMagar plus Gram stain and other simple bench tests gave results similar to those using our current method, but had the advantage of saving time and materials.

Initial testing of a novel urine culture device

The Diaslide urine culture device consists of a hinged case containing two opposing agar media separated by a sampler with a handle at one end and two bent sampler tips at the opposite end. The tips of the sampler are first dipped into the urine. The sampler is then pulled out through the casing, simultaneously inoculating both agar surfaces with a streaking dilution. As a result, individual colonies can be observed even when bacterial concentrations exceed 10(6) CFU/ml. The number of colonies on the Diaslide correlated linearly with CFU per milliliter as determined by dilution plating. The clinical performance of the Diaslide was compared with those of ordinary dipslides and conventional cultures with a sample of 473 prescreened hospital urine specimens. The sensitivity, specificity, and positive predictive value of Diaslide versus those of culture at the 10(4)-CFU/ml cutoff level were 97.5, 98.3, and 98.3%, respectively, compared with 98.8, 95.7, and 97.2%, respectively, for dipslide versus culture. Similar results were found at the 10(5)-CFU/ml cutoff level. Only 5.5% of the Diaslides required subculturing, compared with 14.7 and 9.4% of the dipslides and conventional cultures, respectively. The Diaslide proved more convenient than an ordinary dipslide for sampling low volumes of urine. These data suggest that the Diaslide is a simple, effective device for culturing of urine specimens.

Criteria for diagnosis of urinary tract infection and evaluation of therapy

Patients with urinary tract infections are commonly used to study the efficacy of new antibiotics. Some criteria, for example the presence of more than 100,000 organisms of a single species per ml as an indicator of infections, have been accepted for many years but all rules have exceptions. Other criteria such as relapse, re-infection are less clearly agreed. Furthermore, timing of collection of specimens during and after treatment shows great variation in protocols and in definition. These criteria and the methodology of collecting, transportation and examination of urine are discussed.

Characteristics of bacteriuria in a homogeneous maternity hospital population

Bacteriuria and urinary tract infection are a common cause of morbidity in pregnancy. Recent evidence has, however, questioned the magnitude of this risk and the effectiveness of therapy in reducing it. To clarify matters, a prospective study on 3123 ante-natal women was carried out. Screening for bacteriuria was carried out by culturing a mid-stream specimen of urine. Treatment was given to all patients with a positive culture and was based on antibiotic sensitivity testing. Repeat culture was performed 1 week after completion of therapy. The prevalence of bacteriuria in our population was 4.74%. Over half of these patients were asymptomatic. 67% of those with bacteriuria at screening were symptomatic or had a past history of urinary tract infection. Escherichia coli was the predominant organism cultured. The most effective antibiotic was Nitrofurantoin, which was sensitive in over 90% of isolates. Late urinary tract infection occurred in 3.52% of patients. There was no increase in maternal or foetal complications amongst those with bacteriuria. We concluded that it might be more cost-effective to confine screening to those patients who are symptomatic or have a past history of urinary tract infection.

Evaluation of enzyme linked immunosorbent assay for screening urinary tract infection in elderly people

AIMS

To evaluate the Uristat test, an indirect enzyme linked immunosorbent assay for the qualitative detection of antibodies in urine, as a screening, and in the diagnosis of urinary tract infection in the elderly.

METHODS

Semiquantitative culture was compared with conventional microscopy, dipstick analysis and the ELISA. In the ELISA, 371 urine samples were examined for antibodies to an antigen mixture of six common urinary pathogens.

RESULTS

The sensitivity was 91% and the specificity 25% for the ELISA. The negative predictive value was 81% and the positive predictive value was 43%.

CONCLUSIONS

In its present form the Uristat test has no clear advantages over conventional bacteriological techniques for screening urine samples for infection in an elderly population.

Audit of catheter urine culture requests

An audit to assess the appropriateness of catheter urine culture requests was carried out for a period of one month. The requests were followed up by members of the Infection Control Team at ward level. The laboratory report had no impact on the removal of the catheter in asymptomatic or symptomatic patients, although the reports did aid antibiotic prescribing in symptomatic patients.

Urinary tract infection in pregnancy

During the period January 1987 until January 1988, midstream urine specimens were collected during the first antenatal visit of 2,642 pregnant patients. The specimens were obtained for the purpose of microbiological study. Significant bacteriuria was found in 15.8% (N = 419); 188 of the patients were asymptomatic and 231 were symptomatic, yielding an incidence of 7.1% and 8.7%, respectively. Two hundred females with negative urine cultures were selected as a control group, and matched by age, gravidity, and gestational age. The frequency of occurrence of premature birth was found to be higher only in the symptomatic group (P<0.05), while the frequency of anemia, hypertension, and diabetes was found to be higher in both symptomatic and asymptomatic patients, compared with the control group (P<0.04).

Evaluation of four screening tests for bacteriuria in elderly people

Four screening tests for bacteriuria were assessed at ward level in 418 elderly subjects and were compared with standard methods of bacterial culture. The tests were visual appearance; microscopy; dipstick for nitrite, leucocyte esterase, protein, and blood; and dipstick for nitrite and organisms. The sensitivity of the tests varied from 85.6% to 98.3%, and the specificity from 18.4% to 82.9%. A combination of visual appearance and dipstick testing for nitrite and leucocyte esterase gave a sensitivity of 96.1% with a specificity of 50.6%, and could have reduced by almost one-third the number of urine samples submitted to the laboratory for processing.

Evaluation of six screening methods for detecting significant bacteriuria

Six screening methods for the successful detection of significant bacteriuria--electrical impedance (Malthus), automated acridine-orange staining (Autotrak), particle counting (Ramus), bioluminescence, nitrite and leucocyte test strip (BM Nephur), and microscopy--were evaluated. All had excellent predictive values for a negative result (97%-100%) but were less accurate in predicting a positive result (31%-83%). All methods had high sensitivities (83%-100%) but lower levels of specificity (68%-79%). Bioluminescence was the method with the highest specificity (79%) and the lowest rate of false positive results (15%). It would be inappropriate to decide on treatment and management on the basis of the positive results achieved with any of the methods evaluated, but all methods tested could be used for screening out negative results.

Evaluation of a new commercial kit (UROBACT) for detection of bacteriuria

A new commercially available method (UROBACT, AB Dermaci, Sweden) for detection of bacteriuria was compared to a conventional semiquantitative bacteriological method. The kit consisted of two tubes, which were inoculated with urine in two different dilutions. Positive tests were recorded as a colour change from red to yellow in both tubes, and the test was considered negative if one or both tubes remained red. When studying 556 urine samples, the test detected 153 of 163 samples with greater than or equal to 10(5) colony forming units (CFU) of bacteria per ml, i.e. the sensitivity was 93.9%. Among the samples containing less than 10(5) CFU/ml, 347 of 357 were recorded as negative, giving a specificity of 97.2%. Although relatively few urine samples containing Staphylococcus saprophyticus and Pseudomonas pyoceanea were tested the results indicated that the method was less reliable for these species. However, compared to dip-slides, which also give poor results with S. saprophyticus, the new test has several advantages, including a more simple interpretation, i.e. a distinct colour change.

Cross-resistance of nalidixic acid resistant Enterobacteriaceae to new quinolones and other antimicrobials

One hundred urine isolates Enterobacteriaceae screened for resistance to 30 micrograms nalidixic acid by disc diffusion test were examined by MIC determination for in vitro susceptibility to nalidixic acid, ciprofloxacin, enoxacin, gentamicin, nitrofurantoin, trimethoprim, cephalexin and ceftazidime. Those resistant to nalidixic acid and also gentamicin or a cephalosporin were further examined to determine the mechanism of resistance. Compared to the total urine isolates of Enterobacteriaceae from the same time period, this population as a whole was less susceptible to all antimicrobials tested except gentamicin. Strains that exhibited multiple resistance had the conventional mechanisms of resistance to those antimicrobials. No multiply resistant strains had a permeability barrier due to outer membrane protein alterations causing cross-resistance to chemically unrelated classes of antimicrobials.

Prevalence of urinary tract infection in homosexual and heterosexual men

Homosexual practices might be expected to result in an increase in urinary tract infection in adult men. Midstream urine specimens were collected from 200 homosexual and 205 heterosexual men attending a clinic for sexually transmitted diseases. Three specimens from each group yielded more than 10(5) Escherichia coli per ml. The prevalence of urinary tract infection among homosexuals was therefore similar to that in the heterosexual population.

Technique for the culture and direct sensitivity testing or large numbers of urine specimens

A technique was required for batch culturing and direct sensitivity testing of urine specimens to reduce increasing demands on laboratory services. A comparison was made between the filter paper strip method and multipoint inoculator technique using a Denley inoculator (Denley Ltd, Billingshurst, Sussex). The results showed that multipoint inoculation was a rapid, economical, and reliable method for the handling of large numbers of urine samples.

Bacterial study of clean intermittent catheterisation in children

Deterioration of the upper urinary tract is exceptional in children on clean intermittent catheterisation for neuropathic incontinence and is found only in those with pre-existing renal damage. This report describes a bacteriological study of 24 children, of whom 10 had renal damage and 14 did not have renal damage before clean intermittent catheterisation began. Boric acid was added as a preservative to samples of urine in preference to the use of dip-slides because it preserves pus cells as well as bacteria. The incidence of bacteriuria in the two groups was similar (78% of samples from those with, and 72% of samples from those without, pre-existing renal damage). The groups differed in that the urine of children in the group with pre-existing renal damage yielded organisms other than Escherichia coli more than twice as often as did the urine of those children without renal damage. Moreover, the children with pre-existing renal damage were more likely to have fever with urinary tract infection and some of them showed frequent changes of organisms in the urine. Whatever organism was present, however, children in the group with renal damage more often had heavy pyuria.

Minocycline in chronic abacterial prostatitis: a double-blind prospective trial

In patients with chronic abacterial prostatitis, a double-blind trial of 3 months of treatment with minocycline 100 mg twice daily compared with diazepam 5 mg twice daily was undertaken. The percentage fall in polymorphonuclear leucocyte counts in the expressed prostatic secretions was much more marked after treatment with minocycline than with diazepam. Over a follow-up period of at least 12 months, further treatment was necessary in more patients originally treated with diazepam than with minocycline.

Semiautomated method for quantitative urine culture

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Detection of bacteriuria by bioluminescence: effect of pre-analysis centrifugation of specimens

Three bioluminescence-based, rapid methods of detecting significant bacteriuria were applied in parallel to 514 urine specimens. The results were compared with those of a quantitative pour plate viable count method, defined as positive if greater than or equal to 10(5) c.f.u./ml of urine were observed. When adjusted to yield 21% falsely positive results the three rapid methods yielded 24%, 21% and 19% falsely negative results. If specimens with evidence of urethral or vaginal contamination were excluded (237 specimens remaining) the three methods yielded respectively 14%, 8% and 13% falsely negative results. A major source of disagreement between the bioluminescence-based methods and quantitative culture thus appeared to be contaminated urine specimens.

Degradation of beta 2-microglobulin in infected urine by leukocyte elastase-like activity

Loss of beta 2-microglobulin in human urine at near neutral pH is described. beta 2-Microglobulin was found to be unstable at pH 7.4 in 15 out of 70 specimens with bacterial infection. Breakdown of this protein was shown to be most active between pH 6.5 and 8.0 but some proteolysis also occurred between pH 5.0 and 6.0. Evidence that proteolysis of beta 2-microglobulin near neutral pH is due to neutrophil elastase-like activity was obtained by the following methods: use of the model elastase substrate L-pyroglutamyl-L-prolyl-L-valine-p-nitroanilide and the specific inhibitor 2-trifluoroacetylaminobenzenesulphonyl fluoride; use of neutrophil granule extracts and determination of the size distribution of beta 2-microglobulin proteolytic fragments. If increased numbers of pus cells are present, it is suggested that screening for elastase-like proteolysis should be undertaken before interpreting a measurement of beta 2-microglobulin.

A method for recognising non-bacterial prostatitis: preliminary observations

Chronic non-bacterial prostatitis is a difficult condition to diagnose accurately either by symptoms and signs or by investigations. Four groups of patients were assessed for the number of leucocytes and the presence of pathogens in expressed prostatic secretions before and after treatment with co-trimoxazole two tablets twice daily for three months. The pretreatment findings suggest that the upper limit of normal for the number of leucocytes in expressed prostatic secretions is about five per microscope field (X 40 magnification) and that for the cell count about 0.5 X 10(9)/l using the method described. Increased microscopical cell estimations and cell counts in the expressed prostatic secretions of patients with symptoms of prostatitis and those with recurrent non-specific urethritis seem to indicate the presence of prostatitis.

Treatment of infection in the presence of an indwelling urethral catheter

It is unnecessary to treat laboratory-diagnosed urinary tract infection in the absence of clinical symptoms and signs in patients from whom specimens of urine have been taken from indwelling urethral catheters left in situ for more than one week. If there is clinical evidence of infection, the catheter should be removed, a new catheter inserted and a specimen taken for examination. Alternatively, a suprapubic aspirate of urine may be examined bacteriologically as a treatment guide. In the absence of symptoms or other signs of infection it is doubtful whether chemotherapy is indicated.

Evaluation of the Lumac kit for the detection of bacteriuria by bioluminescence

Four hundred and twenty-two urine samples were screened for significant bacteriuria using bioluminescence and microscopy of uncentrifuged urine. A smaller number of false-negatives were seen with bioluminescence (10%) than with microscopy (40%) while both techniques gave a similar number of false-positives (18%). The kit required a large amount of manual preparation, largely pipetting. With this and the short shelf-life of the reconstituted reagents, it is not suitable for small numbers of urines. At 45p per urine, the cost of bioluminescence is too high.

Emergence of trimethoprim-resistant enterobacteria in patients receiving long-term co-trimoxazole for the control of intractable urinary-tract infection

In patients with previously intractable urinary-tract infection treated with low-dose co-trimoxazole for 6--58 (mean 32.7) months, the percentage of infected urines fell from 41.4 before treatment to 6.3 during treatment. Only 6 episodes of infection were due to trimethoprim-resistant bacteria. Results in a small group of patients in whom treatment was continued with trimethoprim alone were similar. Under the conditions of this study, long-term control of urinary-tract infection was not materially compromised by breakthrough infections due to trimethoprim-resistant organisms.

Incidence and outcome of symptomatic urinary tract infection in children

The incidence of symptomatic urinary tract infection in 2879 children aged under 15 years was studied over 18 months in a single general practice. Infection was diagnosed if bacterial counts in three consecutive samples exceeded 100,000/ml. The incidence of urinary tract infection was 1.7 per 1000 boys at risk per year and 3.1 per 1000 girls. These values are lower than those of comparable studies, possibly because of the stricter diagnostic criterion used in the study. Urinary pus cell counts were also carried out and sometimes found to be misleading. Of the 14 children found to have an infection, three had a radiological abnormality. Five of the children had a recurrence of infection within the first two years, and one an asymptomatic bacteriuria seven years after diagnosis. Only six out of 34 children presenting with dysuria had infected urine, and an association was discovered between abacterial dysuria (or the urethral syndrome) in the remainder and a concurrent upper respiratory tract infection. All children should undergo radiological investigation after their first confirmed infection. Diagnosis and management could be improved by providing all general practitioners with a semiquantitative method of urine culture such as the dip slide.

Bacteria causing symptomatic urinary tract infection or asymptomatic bacteriuria

One thousand bacterial isolates from consecutive suprapublic aspirations of urine in two groups of patients with symptomatic urinary tract infection and two groups with asymptomatic bacteriuria were studied. Staphylococci accounted for 13 and 27% of the isolates from symptomatic patients but for only 3 and 4% of strains from asymptomatic bacteriuria. Conversely, 18 and 30% of Escherichia coli isolates from asymptomatic bacteriuria were auto-agglutinable when tested with antisera to the common urinary O-serogroups, whereas such strains accounted for only 5 and 7% of the E. coli from symptomatic patients. The high prevalence of auto-agglutinable E. coli in asymptomatic bacteriuria was accompanied by a reduction in the frequency of the common uninary O-serogroups rather than other smooth strains.

Particle size distribution analysis for the rapid detection of microbial infection of urine

The accuracy and practicality of particle size distribution analysis for rapid screening of urine specimens are assessed. Six hundred urines were subjected simultaneously to routine bacteriological examinations and particle size distribution analysis using a Coulter Counter (ZBI) linked to a C1000 Channelyzer. There was complete agreement in the results of 593 (98.8%) specimens. Characteristic profiles of various bacterial species in infected specimens were consistently obtained. This system can easily be linked to any existing computer reporting in a district hospital laboratory, and the results of negative specimens (70--80%) can be obtained within 5--10 minutes.

R-factor mediated trimethoprim resistance: result of two three-month clinical surveys

All urinary tract isolates were monitored in the Whittington Hospital, London for trimethoprim resistance over a three-month period in 1975; this survey was repeated 18 months later in 1977. In the later survey the incidence of trimethoprim resistance had increased significantly, and the proportion of strains carrying R-factors conferring trimethoprim resistance had nearly doubled. The pattern of resistances associated with R-factor trimethoprim resistance also changed betweeen these two surveys.

Urinary tract infection in a clinic for sexually transmitted diseases

A study of the prevalence of urinary tract infection (UTI) in 430 women attending a clinic for sexually transmitted diseases and its relationship to sexual activity is presented. UTI, usually asymptomatic, was found to be slightly more common in women attending the clinic than in the general population, its prevalence being 4.9%. UTI was more commonly found in patients who gave a history of recent sexual intercourse, which suggests that recent coitus was a factor in the development of significant bacteriuria. The likelihood of finding significant bacteriuria was not related to the number of sexual partners in the previous year. Trichomoniasis was more common in the small group of patients with UTI than in other women. The most common causative organism of UTI was Escherichia coli, and the isolates were usually sensitive to ampicillin, sulphonamides, trimethoprim, and nitrofurantoin.

Sepsis rates in hip replacement surgery with special reference to the use of ultra clean air

A study is reported of sepsis rates in 836 total hip replacements carried out in various physical environments including ultra-clean air. In a further sutdy the bacteriology of the air around the wound and of the wound itself was investigated during the course of 32 joint replacement operations with and without ultra-clean air. Bacteriological contamination of the air was markedly reduced by the use of ultra-clean air but the wounds themselves were no cleaner than with conventional air conditioning provided that unsterile personel were kept at least Imetri away from the sterile area. The sepsis rate was high at the outset of the study (when a physically apalling theatre was in use, the operative technique was novel and prophylactic antibiotics were not employed). Thereafter it fell and remained unchanged in spite of the introduction of ultra-clean air. We conclude that the efficacy of techniques amiced at sterilizing the air around the wound may now be unprovable in view of the low sepsis rates which can be obtained in a conventional environment. Our results do however show that unsterile personel should not be allowed to approach within Imetri of the sterile area, whatever venitlation is employed.