engleski

Urinary tract infections in South Croatia: Etiology and antimicrobial resistance

Introduction: Urinary tract infections occur very often in outpatients. The aim of this study is to determine causative agents in community acquired urinary tract infection in population in South Croatia, as well as to determine in vitro susceptibility of isolates, and to suggest optimal empirical antibiotic therapy in these patients. Material and methods: In this study, 5080 urine isolates from patients with community acquired urinary tract infection were enrolled in this study. Isolates were collected in a 6-month period, from April 1 to September 30, 2002 in South Croatia (Split and Dalmatia County), isolation of bacteria from urine specimens was performed by surface streak procedure on CLED agar (bioMerieux, France). Identification was performed by conventional biochemical tests as well as API 10S (bioMerieux, France), and susceptibility testing was performed by disk diffusion method according to recommendations of NCCLS. Only results of testing for peroral antibiotics were included, because in outpatients settings they were the only appropriate for treatment of urinary tract infections. Susceptibility were tested to amoxycillin (AMX), amoxycillin-clavulanate (AMC), cephalexin (CN), cefuroxime (CXM), ceftibuten (CTB), trimethoptim-sulfarnethoxazole (STX), norfloxacin (NOR) and nitrofurantoin (NF). Results: From total number of 5080 isolates, 4180 (82.28%) were Gram-negative isolates, and 900 (17.72%) were Gram-positive. From Gram-negatives, the most often isolates were Escherichia coli (62.62% from total number of isolates), followed by Proteus mirabilis (5.31%), Pseudomonas spp. (3.46%) and Klebsiella spp. (2.38%). Among Gram-positives, the most often isolates belonged to enterococci (10.18%), Streptococcus agalactiae (3.84%), and Staphylococcus (3.70%) including 1.00% of S. aureus and 2.70% of coagulase-negative isolates. Antibiotic resistance in Gram-negative isolates is shown in the following table. Resistance to norfloxacin and ceflibuten in Pseudomonas isolates was 49.42% and 60.00% respectively. Among Gram-positive isolates, there was no resistance to amoxycillin, amoxycillin-clavulanate, and nitrofurantoin in enterococci. In Streptococcus agalactiae isolates there was no resistance to amoxycillin, amoxycillin-clavulanate, while 3.59% strains were resistant to cephalexin, 53.85 to trimethoprim-sulfamethoxazole and 1.94% to nitrofurantoin. S. aureus isolates were 61.22% methicilin- resistant, and resistance rate to trimethoprim-sulfamethoxazole was 23.53%, norfloxacin 60.78% and to nitrofurantoin 2.33%. Among coagulase-negative staphylococci, methicillin-resistance was found in 41.48% isolates, and resistance to trimethoprim-sulfamethoxazole, norfloxacin and nitrofurantoin was 26.28%, 30.88% and 3.41%, respectively. Conclusion: The best in vitro susceptibility in E. coli isolates was shown to ceftibuten, followed by cefuroxime nitrofurantoin and amoxycillin-clavulanate. Strains of E. coli showed high frequency of resistance to trimethoprim-sulfamethoxazole and amoxycillin, which is the most common empirical therapy of urinary tract infections in our region. Cefuroxime and ceftibuten were the first choice for Proteus mirabilis, and ceftibuten and norfloxacin for Klebsiellae. Among Gram-positives excellent susceptibility was shown to penicillins, except in staphylococci, where high rate of methicillin-resistant isolates was observed. Respecting the fact that most of the isolates in our region belonged to Gram-negatives, and most of them were E. coli, antibiotic of the first choice for empirical antibiotic therapy in patients in our region would be ceftibuten while other choices would be cefuroxime or norfloxacin. Taking into consideration the fact that the cause of urinary tract infection can be enterococci, staphylococci or Klebsiellae, which are highly resistant to cephalosporins, the best advice to general practitioners is to send their patient's urine to a microbiologist for isolation of bacteria causing urinary tract infection and testing their susceptibility.

UTI ; antimicrobial resistance

nije evidentirano