Radar Jehan Farooqui  ( Department of Clinical Microbiology, The Aga Khan University Hospital, Karachi. )
Mohammed Khurshid  ( Departments of Pathology, The Aga Khan University Hospital, Karachi. )
Mehboob Alam  ( Department of Clinical Microbiology, The Aga Khan University Hospital, Karachi. )

Over two years, 9892 mid-stream urine samples from patients attending the Aga Khan University Hospital, Karachi were cultured. Significant bacterial growth was seen in 23.5% samples. Further iden­tification of these organisms Eevealed 40% of E.coli, 16% Pseudomonas aeruginosa, 11% Klebsiella aerogenes, 5.0% Enterobacter sp., 13% Protdus sp., 4.0% Serratia liquifaciens, 1.0% Acinetobacter sp., 3.0% Citrobacter sp., 4.0% Enterococci, 0.5% Staphylococcus aureus. Results of sensitivity tests performed with antibiotics Ampicillin, Cotrimoxa.zole, Nitrofurantoin, Nalidixic acid, Gentamicin, Amikacin, Pipemedic acid, Cefotaxime, Azactain and Carbenicillin did not reveal any distinct pattern (JPMA 39:129,1989).

Urinary tract infection is a commonly ob­served condition in clinical practice¹. Studies show prevalence rate of 1-2% in neonates, mostly boys and upto 2.0% in school girls, some 50 times more than those of boys of similar age. Figures available for pre-school children suggest that it tends to be­come commoner in girls during infancy². The pre­valence of bacteriuria in adult men is low 0.1 or less until the later years where surveys have shown prevalence of bacteriuria to be about 4-15%^3-6. The diagnosis of urinary tract infection cannot be made without bacteriological culture of urine. Pa­tients with classic symptoms of urinary tract infec­tion may have sterile urine and asymptomatic patients may have infected urine. The laboratory diagnosis of a primary urinary tract infection depe­nds upon the demonstration of significant bac­ teriuria i.e. 1&organisms per ml by quantitative culture of freshly voided sample of urine^7-9. The effective management of urinary tract infection needs the knowledge of various orga­nisms and theft sensitivities to antibiotics. The present study was undertaken at The Aga Khan University Hospital, Karachi to provide this data.

1992 samples of urine were collected ran­domly, for culture and sensitivity tests, from pati­ents of Medical, Surgical, Paediatric wards and patients attending out-patients departments of The Aga Khan University Hospital and also those referred from other general practitioners in Karachi. Samples coliected in sterile screw capped containers as a mid- stream urine were sent to the Microbiology Laboratory within an hour of collec­tion^2,9. Samples which could not be delivered wi­thin an hour were refrigerated at 4°C for upto 24 hours¹⁰. Each urine sample was mixed well and by using a 5 mm diameter calibrated loop¹¹ was cul­tured by Cystine Lactose Electrolyte Deficient (CLED) agar plates. Plates were included at 37°C for 24 hours and colony formation units were counted for the presence of bacteria in urine. All significant Gram negative rods were ide­ntified by an Anal2ytical Profile Identification (A.P.I. 20E) system¹² Antibiotic ‘sensitivities tests were done on diagnostic sensitivity plates (DST) by Stoke’s me­thod¹³.

Table I shows the commonest bacteria caus­ing urinary tract infection in out-patients is E.coli. Pseudornonas aeruginosa is the commonest cause of urinary tract infection in hospitalized patients. Table II shows resistance pattern of isolates. E.coli, the most common organism isolated show­ed a high resistance pattern to Ampicillin and Cotrimoxazole 58% and 60% respectively. Gen­erally a higher percentage of the organisms isolated were resistant to Ampicillin and Cotrimoxazole as compared with other antibiotics as shown in Table II.

The study shows E.coli as the commonest or­ganism causing urinary tract infection. This is in kee3ping with the studies carried out by Ahmad et al¹³ from Karachi. Studies from West also show £.coli as the most common urinary pathogen^15,16. The frequency of other organisms isolated in our study also coincides with Ahmad el al¹³. However, the resistance patterns of these or­ganisms are different to those reported byAhmad et al¹³ in 1975 where the most frequent organism E.coli was 62% resistant to Ampidilhin and 13% resistant to Cotrimoxazole, whereas our study sho­ws a similar resistance pattern to Ampicillin and 60% resistance to Cotrimoxazole, an increase in resistance towards Cotrimoxazole from 13% to 60%. The other isolated organisms show a similar pattern to those reported earlier¹⁴. Abbas et al¹⁶ have also carried out antibiotic sensitivity study in children with urinary tract infection but did not quote any figures. It appears that E.coli is still the commonest pathogen in urinary tract infection and the bac­terial spectrum has not changed over the last 10 years. However, due to frequent and perhaps un­warranted use of Cotrimoxazole, resistance has in-creased making it unsuitable as front-line an­tibiotic in urinary tract infection. The Aga Khan University Hospital’s study points to the need of frequent monitoring of bac­terial spectrum in urinary tract infection and their antibiotic sensitivities so that front-line or blind antibiotic therapy could be designed. Based on our current results, we would recommend Nitrofuran­tom as a drug of choice for the treatment of uri­nary tract infection and Gentamicin for more serious infections. However, we must stress uri­nary tract infections should be investigated fully including microbiological cultures and antibiotic sensitivity tests.

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