European guidelines for urinalysis: a collaborative document produced by European clinical microbiologists and clinical chemists under ECLM in collaboration with ESCMID
2001; Elsevier BV; Volume: 7; Issue: 4 Linguagem: Inglês
10.1046/j.1198-743x.2001.00237.x
ISSN1469-0691
AutoresOlov Aspevall, Hans O. Hallander, Vanya Gant, Timo Kouri,
Tópico(s)Bacterial Identification and Susceptibility Testing
ResumoUrinalysis is one of the most common examinations in microbiological and chemical laboratories as well as at points of care. In addition to bacterial cultures, the term urinalysis encompasses here most common chemical tests related to diseases of the urinary tract and urine particle counting (urine microscopy). Several existing documents can be consulted for details on the microbiological examination of urine [1Clarridge JE Johnson JR Pezzlo MT Cumitech 2B: Laboratory diagnosis of urinary tract infections. American Society for Microbiology, Washington DC1998Google Scholar, 2Murray PR Baron EJ Pfaller MA Tenover FC Yolken RH Manual of Clinical Microbiology. 7th edn. American Society for Microbiology, Washington DC1999Google Scholar, 3Kunin CM Urinary tract infections. Detection, Prevention, and Management. 5th edn. Williams & Wilkins, Baltimore1997Google Scholar, 4Sobel JD Kaye D Urinary tract infections.in: Mandell GL Bennett JE Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 4th edn. Churchill Livingstone, New York1995: 662-689Google Scholar, 5Aspevall O Hallander H Referensmetodik För Urinvägsinfektioner/Bakteriuri, I5. Reference Methodology for Urinary Tract Infections/Bacteriuria. 2nd edn. Swedish Institute for Infectious Disease Control, Stockholm2000Google Scholar, 6Gatermann S Podschun R Schmidt H et al.Fachgruppe ‘Diagnostische Verfahren in der Mikrobiologie’ der Deutschen Gesellschaft für Hygiene und Mikrobiologie, DGHM. Harwegsinfektionen. Qualitätsstandards in der mikrobiologisch‐infektiologischen Diagnostik. MiQ. Gustav Fischer, Berlin1997Google Scholar]. While quite a few national guidelines covering aspects of urinalysis have also been published [7NCCLS Urine Sediment Analysis. JCCLS Guideline GP1‐P2. Toa Medical Electronics Ltd, Kobe1995Google Scholar, 8Koivula T Grönroos P Gävert J et al.Basic urinalysis and urine culture: Finnish recommendations from the working group on clean midstream specimens.Scand J Clin Lab Invest. 1990; 50: 26-33Crossref Scopus (17) Google Scholar, 9National Committee for Clinical Laboratory Standards Urinalysis and Collection, Transportation, and Preservation of Urine Specimens. NCCLS Document GP16‐A. NCCLS, Wayne1995Google Scholar], there is no general international standard or consensus document applicable for, for example, accreditation or validation of new technology available. Recently, a group chaired by Dr Timo Kouri, Tampere, Finland published the European Guidelines for Urinalysis [10Scand J Clin Lab Invest. 2000; 60 (The complete text of this supplement is also available from Taylor & Francis at): 1-96http://www.tandf.nosjcliPubMed Google Scholar] under the auspices of the European Confederation of Laboratory Medicine (ECLM). The complete text of this supplement is available in electronic form from Taylor & Francis at http://www.tandf.no/sjcli. These guidelines were prepared together with the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Working Party on Urinalysis, moderated by Dr Vanya Gant, London, UK, to guarantee the quality of the written guidelines from the microbiological point of view. Several experts from most European countries have also contributed to the review of the draft document. An introduction to the project and the recently published paper for clinical chemists is given elsewhere [11Kouri TT Gant VA Fogazzi GB Hofmann W Hallander HO Guder WG Towards European urinalysis guidelines. Introduction of a project under European Confederation of Laboratory Medicine.Clin Chim Acta. 2000; 297: 305-311Crossref PubMed Scopus (35) Google Scholar]. This paper aims to introduce the guidelines to European clinical microbiologists. The ECLM European Urinalysis Guidelines discuss the complete process of clinical urine analysis. They embrace indications for urinalysis at several stages: diagnostic strategies; patient preparation; specimen collection and transport; measurement procedures for chemical, morphologic and microbiological analyses; quality assurance; and transmission of information, i.e. requests and reports. A stepwise strategy for microbiological urinalysis is also presented (Figure 1). Diagnostic schemes are outlined for symptomatic low-risk patients, symptomatic high-risk patients, and asymptomatic bacteriuria, respectively. Acutely ill patients need an examination with high specificity to reliably demonstrate the presence of bacteria to support an immediate treatment decision, while the rest of the cases can await results from bacterial cultures. A high-performance, high-throughput screening procedure with low false-negative rates would identify true negatives and allow significant reduction in costly and unnecessary urine culture. The guidelines supply detailed instructions for the collection, preservation and transport of specimens obtained from each patient category, to include patients with indwelling catheters and children. Practical and useful illustrations on specimen collection are presented and offered for implementation at the end of the book (also seen in the website of the project at Tampere University Hospital (http://www.pshp.fi/labnet/EUgroup.htm)). Collection containers, preservation and transport are also discussed. Detailed methods are presented in four appendices. The authors have chosen to classify diagnostic measurement procedures (methods) hierarchically into four levels of performance based on accuracy of measurement: level 1, rapid procedures such as dipsticks with ordinal scale reporting; level 2, routine (quantitative) procedures in common clinical laboratory use; level 3, qualified comparison procedures; and level 4, primary reference measurement procedures (previously referred to as ‘definitive methods’) that are designed to give the true value of the measurand (analyzed component). In microbiology, no such primary procedures are available. Procedures for bacterial culture can be outlined at three levels: 1.Level 1, screening procedure. Dipslide culture used to identify negative cultures and significant growth of Escherichia coli only.2.Level 2, routine procedure. One microliter is inoculated on CLED agar (blood agar being an option) and incubated aerobically for 24 h.3.Level 3, qualified comparison procedure. Ten microliters of urine is inoculated by pipette on CLED agar, hematin agar and blood agar aerobically, and cultured anaerobically in carbon dioxide for 48 h. The proposal to use a liter-based unit, CFB/L (colony-forming bacteria/L), in reports of bacterial concentration in urine instead of CFU/mL (colony-forming units/mL) is an important step in metrological standardization. The character B instead of U was chosen to avoid confusion between exponentials which might result if only mL volumes were changed to L volumes. The authors also decided to use a novel classification system for organisms causing urinary tract infections based on criteria of pathogenicity, as developed in Sweden (Table 1).Table 1The pathogenicity and frequency of microorganisms in midstream urineFrequency (% of isolates)Pathogenicity in the urinary tractA. Common (>10%)B. Fairly common (1–10%)C. Uncommon (0.1–1%)D. Rare (<0.1%)L. Primary pathogensE. coliS. saprophyticusE. coli CO2-dependent, Salmonella spp.aLow concentrations are reported even if they are most likely caused by contamination during specimen collection. (Leptospira, mycobacteria)II. Secondary pathogensEnterobacter spp., Enterococcus spp., Klebsiella spp., Klebsiella spp., Proteus mirabilis, Pseudomonas aeruginosaCitrobacter spp., Morganella morganii, Proteus vulgaris, Proteus vulgaris, Serratia spp., Staphylococcus aureusCorynebacterium urealyticum, Haemophilus spp.,bMost often isolated from children. pneumococciIII. Doubtful pathogensGBScGBS, group B streptococci (S. agalactiae)., yeast, CNS (others)dCNS, coagulase-negative staphylococci, urease-forming isolates or isolates found in patients with indwelling catheters have increased significance.Acinetobacter spp., Pseudomonas spp., Stenotrophomonas maltophiliaA great number of reported cases have been published with exceptional cases of infections caused by other speciesIV. Usually urethral or genital floraeNo identification and susceptibility testing (only exceptionally, if especially indicated). Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 26, by permission of Taylor & Francis AS.α-Streptococci, Gardnerella vaginalis, lactobacilli etc.Bifidobacterium spp., ‘diphtheroid’ rods etc.a Low concentrations are reported even if they are most likely caused by contamination during specimen collection.b Most often isolated from children.c GBS, group B streptococci (S. agalactiae).d CNS, coagulase-negative staphylococci, urease-forming isolates or isolates found in patients with indwelling catheters have increased significance.f No identification and susceptibility testing (only exceptionally, if especially indicated). Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 26, by permission of Taylor & Francis AS. Open table in a new tab The first group consists of E. coli and Staphylococcus saprophyticus causing urinary tract infections in individuals with normal urinary tracts. Secondary pathogenic species often occur in hospital-acquired urinary tract infections. The third and fourth groups refer to doubtful pathogens and urethral or genital flora, respectively. This classification influences the suggested limiting concentrations of bacteria justifying identification and susceptibility testing in the laboratory. Other factors taken into consideration for interpretation limits are specimen type, gender, number of isolated species and presence of symptoms. These limits allow diagnosis of urinary tract infections down to 10 CFB/L from midstream urine in both females and males. We give detailed recommendations on cut-offs which take the above-mentioned factors into consideration (Table 2). General screening of asymptomatic individuals should be avoided.Table 2Suggested limiting concentrations of bacterial colonies justifying identification and susceptibility testing in the laboratory.SymptomsaYes = the patient has symptoms; No = no symptoms, or no information about symptoms. and specimensInoculum, minimum volumeSpecies typebSuggestive category based on growth characteristics (see Table 1). Species of normal urogenital flora (IV) are examined for susceptibility only if especially indicated.Species numberSignificant colony concentrationCFB/LCFU/mLMidstream urine specimenYesaYes = the patient has symptoms; No = no symptoms, or no information about symptoms.1 μLI1–2cUsually, only one species is identified and tested for antimicrobial susceptibility if 2–5 similar colonies grow (as locally agreed). Occasionally, two species may be identified for specific patient populations. Three or more species are usually reported as ‘mixed culture’ and considered as contaminants. Susceptibility testing of isolates from midstream urine specimens as well as other detailed strategic decisions need local clinical and microbiological consultation.106103II1107 (women)104II1106 (men)103II2108105III1108105NoaYes = the patient has symptoms; No = no symptoms, or no information about symptoms.I-III1108105Yes (special)10 μLdA1-μL loop is practical and sufficient for routine workup. However, in specific patient groups, such as in patients with certain urologic diseases, or in the precise evaluation of patients with simple cystitis, a result at ≥105 CFB/L (102 CFU/mL) and a statistically reliable culture result at 106 CFB/L (103 CFU/mL) may be clinically significant. This can only be obtained by using a 10-μL loop. This sensitized culture procedure should be especially requested to avoid extra work and costs caused by routine application of a 10-μL loop for all specimens. Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 30, by permission of Taylor & Francis AS.1–3105102Suprapubic aspiration specimenYes or no100 μLI-IV1–2104101Specimen from cystoscopy or single urethral catheterizationYes or no10 μLdA1-μL loop is practical and sufficient for routine workup. However, in specific patient groups, such as in patients with certain urologic diseases, or in the precise evaluation of patients with simple cystitis, a result at ≥105 CFB/L (102 CFU/mL) and a statistically reliable culture result at 106 CFB/L (103 CFU/mL) may be clinically significant. This can only be obtained by using a 10-μL loop. This sensitized culture procedure should be especially requested to avoid extra work and costs caused by routine application of a 10-μL loop for all specimens. Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 30, by permission of Taylor & Francis AS.I-III1–2105102Specimen from indwelling catheterYes1 μLI-III1–3107104No1 μLI-III1108105a Yes = the patient has symptoms; No = no symptoms, or no information about symptoms.b Suggestive category based on growth characteristics (see Table 1). Species of normal urogenital flora (IV) are examined for susceptibility only if especially indicated.c Usually, only one species is identified and tested for antimicrobial susceptibility if 2–5 similar colonies grow (as locally agreed). Occasionally, two species may be identified for specific patient populations. Three or more species are usually reported as ‘mixed culture’ and considered as contaminants. Susceptibility testing of isolates from midstream urine specimens as well as other detailed strategic decisions need local clinical and microbiological consultation.d A1-μL loop is practical and sufficient for routine workup. However, in specific patient groups, such as in patients with certain urologic diseases, or in the precise evaluation of patients with simple cystitis, a result at ≥105 CFB/L (102 CFU/mL) and a statistically reliable culture result at 106 CFB/L (103 CFU/mL) may be clinically significant. This can only be obtained by using a 10-μL loop. This sensitized culture procedure should be especially requested to avoid extra work and costs caused by routine application of a 10-μL loop for all specimens. Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 30, by permission of Taylor & Francis AS. Open table in a new tab The procedures for bacterial culture mentioned above are described in detail in the microbiological appendix section. In addition, we provide guidance and instructions concerning the minimum criteria for identification of bacteria, serial dilution methods for quantitation, and a level 1 ‘microtiter tray method’ for detecting clear-cut infected urines. Special attention is also paid to near-patient testing. Bacterial detection by non-culture methods is important in emergency diagnostics, as exemplified by test strips for nitrite and leukocyte esterase describing the performance and limits of these reactions. The technical performance of dipslide culture restricts its use to the exclusion of urinary tract infections, and identification of the primary pathogen E. coli. Methods for particle analysis first define basic and advanced levels of urine particle identification for different clinical practices and laboratories (Table 3). The basic level would be mostly used in general or chemistry laboratories and for general patient populations. The advanced level comprises a microbiological direction (Gram staining for microbiology laboratories), anephrologic direction (detection of renal elements, i.e. casts and renal tubular cells), or a cytopathologic direction (detection of atypical epithelial cells and malignancy).Table 3Levels of microscopy differentiation in clinical urinalysisBasic levelAdvanced level in additionRed blood cellsDetailed subclasses of erythrocytes: dysmorphic erythrocytesWhite blood cells/granulocytesDifferentiation of leukocytes: Granulocytes, lymphocytes, macrophages (monocytes and eosinophils)Epithelial cells Squamous epithelial cellsFrom non-squamous epithelial cells: squamous epithelial cellsNon-squamous = small epithelial cellsRenal tubular epithelial cells Transitional epithelial cells (superficial and deep) Intestinal epithelial cells (occurring after bladder surgery) Atypical cells (experienced cytopathologist)CastsFrom non-hyaline casts:Hyaline castsErythrocyte, granulocyte castsNon-hyaline castsRenal tubular cell casts Hyaline, granular, waxy, fatty casts Bacteria and yeast-containing casts Hemoglobin and myoglobin casts Bilirubin castsBacteriaGram-staining characteristics of bacteria (microbiology laboratories)Yeasts TrichomonasSchistosoma haematobium (in appropriate geographic locations)SpermatozoaArtefacts (hair, paper and textile fibers, starch, glass) and mucusArtefacts and mucus as on the leftLipidsLipids, in addition to droplets:Droplets (isolated and aggregated)Oval fat bodies (lipid-laden tubular cells), cholesterol crystalsCrystalsAdditional rare crystals:Urate, oxalate (mono- and dihydrated), phosphate and cystinedrugs, cystine, leucine, tyrosine 2,8-dihydroxyadenine, xanthineReproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60(suppl 231): 21, by permission of Taylor & Francis AS. Open table in a new tab Considerable efforts were made to address the issues of different clinical needs, and we classify routine microscopy techniques into different levels of analytic procedures. Level 1 is suggested to contain screening identification of particles, e.g. by using a microtiter tray method and ordinal scale reporting. Level 2 defines a standardized routine procedure with specific aims, such as: (a) Gram staining for classifying uropathogenic bacteria; (b) standardized urine sediment with supravital staining and/or phase contrast microscopy for precise identification of renal particles; and (c) chamber counting of uncentrifuged urine specimens for accurate counting of red and white blood cells that are partially lost during centrifugation. Level 3 should contain sensitive detection and accurate quantitation of clinically significant urine particles. If bacteria only are considered, the slide centrifugation and Gram-staining technique is recommended because of its proven performance against culture. Thus, general (chemical), microbiological and nephrologic needs for urinalysis may differ, and must be taken into account when specifying routine analytic processes. A chapter on quality assurance gives an extensive discussion on general issues such as quality system, quality manual, and quality policy, as well as very specific matters. Analytic quality specifications are suggested for clinical microbiology laboratories, to help assessment of performance. We suggest (for example) acceptable routine levels of identification for bacteria, and acceptable turnaround times for bacterial cultures. Detail for evaluation of performance of urinalysis devices is provided as a suggestive framework. This document will be most valuable for persons responsible for analysis of urine in clinical chemistry laboratories and in clinical microbiology laboratories. Acceptance and endorsement of the proposed procedures would be a step towards standardization of urinalysis. This would be of great benefit to laboratories and patients alike. Reproduced from Kouri T, Fogazzi G, Gant V, Hallander H, Hofmann W, Guder WG, eds. ECLM. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000; 60 (suppl 231): 4–5, by permission of Taylor & Francis AS. Members of the ECLM European Urinalysis Group Dr Timo Kouri (Chairman)Center of Laboratory Medicine Tampere University Hospital PO Box 2000, FIN-33521 Tampere FinlandTel: +358 3 247 5484 Fax: +358 3247 5554E-mail: Timo.Kouri@tays.fiDr Giovanni FogazziDivisione di Nefrologia e DialisiOspedale Maggiore, IRCCSVia Commenda 15, I-20122 Milano ItalyTel: +39 02 5503 4557 Fax: +39 02 55034550E-mail: croff1@polic.cilea.itDr Vanya GantDepartment of Clinical Microbiology University College Hospital Grafton Way, London WC1E 6DB UKTel: +44171 380 9913 Fax: +44 171388 8514E-mail: v.gant@academic.uclh.nthames.nhs.ukDr Hans HallanderSwedish Institute for Infectious Disease Control Department of Quality Assurance SE-17182 Solna SwedenTel: +46 8 457 2490 Fax: +46 83025 66E-mail: hans.hallander@smi.ki.seDr Walter HofmannInstitute for Clinical Chemistry Stādtisches Krankenhaus Bogenhausen Englschalkinger Strasse 77 D-81925 Munich GermanyTel: +49 89 9270 2282 Fax: +49 89 92702113E-mail: Hofmann-Sedlmeir@t-online.deProfessor Dr Walter G. GuderInstitute for Clinical Chemistry Stādtisches Krankenhaus Bogenhausen Englschalkinger Strasse 77 D-81925 Munich GermanyTel: +49 89 9270 2280 Fax: +49 89 92702113E-mail: w.g.guder@lrz-muenchen.deESCMID Working Party on UrinalysisVanya Gant, London, UK, ModeratorHans Hallander, Stockholm, SwedenFrancis O'Grady, Nottingham, UKMarc Struelens, Brussels, BelgiumOther contributorsAmores C., Jaen, SpainAnyszek Tomasz, Krakow, PolandArnadottir M., Reykjavik, IcelandAspevall O., Huddinge, SwedenBaerheim A., Bergen, Norway/Gent, BelgiumBéné M.-C., Nancy, FranceBlaseio U., Hamburg, GermanyBlondiau R., Erembodegem, BelgiumBondarenko I., St Petersburg, RussiaColombo J. P., Bern, SwitzerlandDelanghe J., Gent, BelgiumDybkaer R., Copenhagen, DenmarkEdel H., Munich, GermanyEmanuel V., St Petersburg, RussiaFang-Kirchner S., Vienna, AustriaFenili D., Romano di Lombardia, ItalyFernandes B., Toronto, CanadaFuellemann R., Mannheim, GermanyGarcia J. L., Sevilla, SpainGatermann S., Bochum, GermanyGrubb A., Lund, SwedenGyōry A.Z., Sydney, AustraliaHesse A., Bonn, GermanyHoeiby N., Copenhagen, DenmarkHofgārtner W., Oxford, UKHyltoft-Petersen Per, Odense, DenmarkIto K., Yokohama, JapanItoh Y, Osaka, JapanIvandic M., Munich, GermanyKermes K., Tartu, EstoniaKhorovskaya L., St Petersburg, RussiaKimling H., Mannheim, GermanyKokot F., Katowice, PolandKontiainen S., Helsinki, FinlandKratochvila J., Nymburg, Czech RepublicKutter D., Junglinster, LuxembourgLapin A., Vienna, AustriaLipsic T., Bratislava, Slovak RepublicMalakhov V., Moscow, RussiaNaber K.G., Straubing, GermanyNaegele U., Mannheim, GermanyNewall R., Newbury, UKNewman D.J., London, UKParker D., Elkhart, IN, USAPeheim E., Bern, SwitzerlandPenev M.N., Sofia, BulgariaPiemont Y., Strasbourg, FrancePonticelli C., Milano, ItalyPrice C., London, UKPugia M., Elkhart, IN, USARada F., Tirana, AlbaniaRecio F., Sevilla, SpainRowan R.M., Glasgow, UKRowlands T., Meylan, FranceSalum T., Tartu, EstoniaSandberg S., Bergen, NorwaySelgren S., Elkhart, IN, USASiitonen A., Helsinki, FinlandSikirica M., Zagreb, CroatiaSteinhausen R., Mannheim, GermanyTetz VV, St Petersburg, RussiaTzontcheva A., Sofia, BulgariaVerhaegen J., Leuven, BelgiumZaman Z., Leuven, Belgium
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