Diagnosis of Urinary Tract infections essential learning by Dr.T.V.Rao MD

Diagnosis of Urinary Tract infections essential learning by Dr.T.V.Rao MD Major number of specimens comes in Diagnostic Bacteriology to be Urine, for Bacteriological Studies and establishing urinary tract infections. Urinary tract infection (UTI) is one of the most common disease, occurring from the neonate up to geriatric age groups. Forty to 50% of adult women have a history of at least one UTI. Urinary tract infection is a major cause of Gram negative sepsis in hospitalized patients and after renal transplantation. Preserving Urine specimens after collection, to be a top priority if the delay is unavoidable in processing the specimens. Laboratories should put efforts to do Microscopic examination for Pus cells and epithelial cells; the counts are reported as given per low-power field or high-power field. Results can be also given per unit volume of urine. At the high magnification (×40) the presence of 1–10 micro-organisms/high-power field is indicative of bacteriuria. The presence of ≥10 white blood cells/high-power field is indicative of pyuria. On many occasions we take Kass et al criteria in diagnosis of urinary tract infection, Traditionally the concept of significant bacteriuria for the diagnosis of UTI was based on the notion that the quantitative bacterial count allowed distinction between infection and contamination. The utility and consistency of the criterion of ≥105 colony-forming units per milliliter (c.f.u. /ml) of cleancatch urine for the diagnosis of UTI has been validated repeatedly. In children, rapid and reliable diagnosis of UTI is mandatory and important to prevent renal damage and other systemic infections. In the changing concept, UTI is defined as bacterial count ≥104 c.f.u. /ml urine, accompanied by microscopical examination of the urine to exclude vaginal contamination (because such contamination frequently results in false-positive culture tests). Studies by Kunin et al. and Arav-Boger et al. ASM suggested that low-count bacteriuria might be an early phase of UTI. The majority of patients with bacterial counts between 102 and 104 c.f.u. /ml has microorganisms typical for UTI (E. coli, Staphylococcus saprophytic us, and enteric Gram-negative bacteria). As the criteria is concerned not possible to implement by Microbiologists unless a optimal clinical information is provided. First, it is likely that symptomatic bacteriuria of <105c.f.u. /ml reflects ongoing UTI, and therefore the microbiological criterion should be reduced to >102 c.f.u./ml in symptomatic patients. Second, a low number of bacteria in the urine may be the result of increased urine output due to high fluid in take we should avoid collecting a specimen when the patient is wakened and already taken sufficient fluids. Is ideal to take a specimen when the patient awakened in the early morning. Third, low-count bacteriuria may be produced by slow growth of some uropathogens such as S. saprophytic us. We have to use a different discrimination when we are reporting specimens from males where the chances of contamination are less and significance of low counts are important for interpretation of low bacterial counts with uropathogens may be clinically meaningful. For infections with S. saprophyticus and Candida species, the lower cutoff level of ≥104 c.f.u./ml is commonly accepted. Contamination is likely if only small numbers of bacteria or several bacterial species grow in urinary culture; Diptheroids, Corynebacteria species, Gardnerella, alpha-hemolytic streptococci, and other aerobes are considered urethral and vaginal contaminants. Even With years of accumulated experience in bacteriological Culturing and reporting urine specimens, Reporting continues to be difficult if taken with good spirit. As we, all lack clinical support in Majority of the institutions in the Developing countries we lack precision is reporting. The reported variations between Microbiologists continue to limit and bring in uniformity in reporting. However, our reporting will not improve unless we follow up with clinical progress of the patient. Above all cautious with specimens collected from Urinary Catheters cause for errors and misreporting

Dr.T.V.Rao MD