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[Antibiotic sensitivity of bacteria isolated from the urine of children with urinary tract infections from 1986 to 1995].


In adults and in children urinary system infections are mostly caused by gram-negative and rarely by gram-positive bacteria. Of gram-negative bacteria the most frequent cause of infections are Escherichia coli, Klebsiella species, Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter, Serratia etc., and of gram-positive bacteria Enterococcus, Staphylococcus, Streptococcus agalactiae. In rare cases the cause of infection may also be Pneumococcus and Haemophilus influenzae.


The aim of the study was to investigate the sensitivity to antibiotics of gram-negative bacteria as the predominant cause of urinary infections.


We isolated 20,615 bacterium species from urine of children hospitalized or treated as outpatients at the University Children's Hospital in Belgrade. Urine was collected classically, i.e. by taking the second clean stream into a sterile test tube or by Uricult test. The samples were cultured on blood plates and endo-agar. Identification was done by standard bacteriologic methods and when findings were dubious API-20E (bioMerieux) was used. Bacterium sensitivity to nine antibiotics (ampicillin, cephalexin, cefotaxime, chloramphenicol, gentamicin, amikacin, co-trimoxazole, nalidixic acid and nitrofurantoin) was assessed with disc diffuse method on Müller-Hinton agars.


Based on the obtained results, Escherichia coli species sensitivity to amikacin, gentamicin, cefotaxime, nalidixic acid and nitrofurantoin ranged from 90 to 100%; sensitivity to co-trimoxazole and chloramphenicol ranged from 70 to 80%, to cephalexin from 50 to 60%, while to ampicillin it was only 20%. Klebsiella species sensitivity to nalidixic acid and cefotaxime was 70-85%; to amikacin, cefotaxime, co-trimoxazole and gentamicin 60-80%; to cephalexin and chloramphenicol 40-50%, and to ampicillin only 5-15%. Proteus species showed sensitivity to amikacin, gentamicin, cefotaxime and nalidixic acid of 90-95%; to co-trimoxazole and chloramphenicol 70-80%; to cephalexin and ampicillin 40-50%, and to nitrofurantoin 10%. Pseudomonas aeruginosa species showed the highest level of sensitivity to amikacin (40-50%), and somewhat lower to gentamicin (10-40%), and a very low sensitivity to other antimicrobial drugs (10-25%).


It may be noted from the above data that gram-negative bacteria are the cause of urinary infections in about 90% of cases, while gram-positive bacteria are the cause in only 10%, which is in accordance with data from literature. Of all antibiotic drugs ampicillin (a wide spectrum penicillin) had a very significant role in the therapy of urinary infections. However, the long-term usage of ampicillin led to increased resistance to the drug in infections caused by Escherichia coli. Natural resistance to ampicillin of Klebsiella species limited its usage when penicillin was first introduced. Proteus mirabilis species, especially those isolate in primary infection, are often sensitive to amino penicillin. Contrary to Proteus mirabilis, indole-positive Proteus and Providentie species show a high resistance to these antibiotics. Due to the crisis in our country and the lack of other antibiotics, ampicillin was widely used. The wide use of the drug caused evident resistance of Escherichia coli and Proteus mirabilis to this antibiotic. A fall in the sensitivity of Klebsiella to cephalexin, gentamicin, amikacin and co-timoxazole, which occurred in 1992, has been explained by intrahospital circulation of multiresistant Klebsiella species. The sensitivity of isolated gram-negative bacteria Escherichia coli, Klebsiella species, Proteus mirabilis and Pseudomonas aeruginosa was the most prominent to aminoglycosides (amikacin and gentamicin). The most frequent mechanism of enterobacterial resistance to trimethoprim and co-trimoxazole involves dihydrofolate reductase enzyme. Comparative studies related to the administration of co-trimoxazole have shown that the difference in the efficacy between thes

Authors+Show Affiliations


University Children's Hospital, Belgrade.




Microbial Sensitivity Tests
Urinary Tract Infections

Pub Type(s)

English Abstract
Journal Article



PubMed ID