The aim of this study was to identify the bacteria causing community acquired urinary tract infections (UTI) and detection of antibiotics resistance of isolates in 912 children below 18 years in the west of Iran. Data were analyzed for 4 age groups: infants, toddlers, preteens and teens. Fourteen antibiotics were tested by gel-diffusion method. Of 912 patients, 34.2% had positive bacterial cultures. The most common isolates were E. coli (57.4%), K. pneumoniae (9.7%), S. aureus (5.8%) and A. baumannii (2.2%). Most isolates showed high resistance against ampicillin, cotrimoxazole, nalidixic acid, tobramycin and nitrofurantoin. Klebsiella isolates showed more resistance against tested antibiotics than E. coli isolates.

Keywords: Antibiotics, Iran, Resistance, Urinary tract infection.

Community acquired urinary tract infections (UTI) cause significant illness in the first 2 years of life and are considered as common disease in school and pre-school children, particularly in our country(1-3). Etiologic agents of UTI are variable and usually depend on time, geographical location and age of patients. However, Enterobacteriacea species including Escherichia coli, Proteus mirabilis, Enterobacter agglomerans, Citrobacter freundii and Klebsiella pneumoniae account for over 70% cases(2-5).

Based on the microbial sensitivity test results, drugs that are usually administered against uropathogens include cotrimoxazole, amoxicillin, ampicillin, aminoglycosides, cephalosporins, nalidixic acid and nitrofurantoin. However, many reports have indicated the presence of multi-drug resistance in organisms causing UTI(6-9). Prior to this study, the antibiotic susceptibility of isolates has not been previously determined in this region. Therefore, the aim of this study was to identify the most common bacteria causing UTI and detection of antibiotic susceptibility of isolates in children.

A cross-sectional study was performed on 912 children with UTI admitted to the pediatric department of hospital of Ekbatan in Hamadan, in the west of Iran, between March 2004 and April 2006. Only patients who had pyuria (>10 white blood cells/µL), acute voiding symptoms and significant bacteriuria (>10⁵ CFU/mL) were included in the microbiological analysis. Data were analyzed separately for four age groups: infants (0-4 weeks), toddlers (5 weeks-24 months), preteens (2-12 years) and teens (13-18 years). Urine collection, culture and identification of organisms were performed as per methods outlined in standard text(2,10).

Susceptibility testing was performed by VITEK (BioMérieux, Inc.) automated system for Enterobacteriaceae. Disk diffusion test (Oxoid, Basingstoke, Hampshire, UK) was used for Gram-positive bacteria and P. aeruginosa. Fourteen antibiotics of different classes (Table I) were tested against isolates. Interpretative criteria for antimicrobials tested were those recommended by NCCLS guidelines(11). E. coli ATCC 25922, S. aureus ATCC 25923 and P. aeruginosa ATCC 27853 were used as quality controls.

TABLE I



Antibiotics Resistance in Escherichia coli and Klebsiella  Pneumoniae in Children with UTI    

Of 912 children, 34.2% had positive cultures. The most common isolates were E. coli (57.4%), K. pneumoniae (9.7%), E. aerogenes (7.0%), S. aureus (5.8%), C. fruendii (5.1%), P. mirabilis (4.5%), P. aeruginosa (3.2%), A. baumannii (2.2%), coagulase-negative Staphylococcus (3.2%) and E. fecalis (1.9%). The most common age were teens (49.6%), preteens (26.8%), toddlers (15.0%) and infants (8.6%), respectively. Most gram-negative isolates were found in toddlers and preteens patients, whereas most gram-positive cocci, particularly E. faecalis isolates were found in teen patients. Acinetobacter baumannii isolates were found mostly (85%) in preteen patients.

The antimicrobial potency of 14 selected antimicrobial agents against the two most frequent uropathogens (E.coli and K. pneumoniae) are summarized in Table I. Among b-lactam antibiotics, imipenem had the widest coverage against E. coli isolates. E. coli resistance to ampicillin peaked in preteens (76.4%) but was high in teens (65.7%), toddlers (53.4%), and infants (47.6%). Resistance to cotrimoxazole peaked in teens (68.3%) but was high in preteens (59.1%), infants (49.4%) and toddlers (47.6%). Klebsiella isolates also showed high susceptibility against imipenem. Antibiotic resistance patterns of other isolates are shown in Table II. Among gram negative bacteria, P. aeruginosa was most resistant isolates against tested antibiotics. Among gram positive cocci, E. fecalis isolates showed highest resistance followed by Staphylococcus isolates. Resistance to two or more antibiotics varied across age groups; teens (36.1%), preteens (33.1%), infants (29.7%) and toddlers (24.9%).

TABLE II



Antibiotic Susceptibility Patterns of Other Bacteria in Children With UTI	 

This is the first study to evaluate the bacteriology and susceptibility patterns of bacteria isolated from children with UTI in west of Iran. The present study showed that the rate of UTI (34.2%) among children was more than that reported previously(1,2,4-6, 12). Entrobactericae isolates were the dominant bacterial agents, in agreement with previous works(4-6,12, 13). E. coli was the commonest isolate, particularly among the toddlers and preteens patients. K. pneumoniae was the second most common uropathogen and was dominant in teens. Gram-positive cocci had low contribution in causing UTI.

This study provides valuable laboratory data on antibiotics susceptibilities of uropathogens and allows comparison of the situation in our area with that in other countries. A limitation of this study was that some antibiotics such as fluoroquinolones and cephalosporins were not available at the time of sensitivity testing. On the basis of reports by Antimicrobial Surveillance Program, isolates from Canada, USA and Latin American countries show the lowest susceptibility rates to most antimicrobial agents followed by Asian-Pacific isolates and European strains(8,9,13,14). Of 14 tested antibiotics in this study, the most active antibiotics against all gram-negative isolates were imipenem, netilmicin, aztreonam, cefepime and ciprofloxacin. Most of these isolates showed high resistance against ampicillin, cotrimoxazole, nalidixic acid, tobramycin and nitrofurantoin. The inadequate dosage of these antibiotics used during self-medication in our community is likely to be a factor contributing to the development of resistant strains. These findings are similar to studies from Africa, South-Asia and some Middle East countries(6,7,12,13,15).

Klebsiella isolates in this study showed more resistance than E. coli isolates. The major difference was observed for gentamicin and amikacin; E. coli isolates showed low resistance to amikacin and gentamicin, while Klebsiella isolates showed high resistance to these agents despite being sensitive for many years(2,8,14).

2. Wald ER. Cystitis and pyelonephritis. In: Feigin RD, Chery JD, Demmier GJ, Kapian SL, eds. Textbook of Pediatric Infectious Diseases, 5th edn, Philadelphia: Saunders 2004; p 541-53.