Frequency and antimicrobial resistance patterns of bacteria implicated in community urinary tract infections: a ten-year surveillance study (2000–2009)

BMC Infect Dis. 2013 Jan 18;13:19.

Inês Linhares1

Teresa Raposo2

António Rodrigues2

Adelaide Almeida1*
* Corresponding author

1 Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal

2 Clinical Analysis Laboratory Avelab, Rua Cerâmica do Vouga, 3800-011 Aveiro, Portugal



Urinary tract infection (UTI) is one of the most common infectious diseases at the community level. In order to assess the adequacy of the empirical therapy, the prevalence and the resistance pattern of the main bacteria responsible for UTI in the community (in Aveiro, Portugal) was evaluated throughout a ten-year period.


In this retrospective study, all urine samples from patients of the District of Aveiro, in ambulatory regime, collected at the Clinical Analysis Laboratory Avelab during the period 2000–2009 were analysed. Samples with more than 105 CFU/mL bacteria were considered positive and, for these samples, the bacteria were identified and the profile of antibiotic susceptibility was characterized.


From the 155597 samples analysed, 18797 (12.1%) were positive for bacterial infection. UTI was more frequent in women (78.5%) and its incidence varied with age, affecting more the elderly patients (38.6%). Although E. coli was, as usual, the most common pathogen implicated in UTI, it were observed differences related to the other bacteria more implicated in UTI relatively to previous studies. The bacteria implicated in the UTI varied with the sex of the patient, being P. aeruginosa a more important cause of infection in men than in women. The incidence of the main bacteria changed over the study period (P. aeruginosa, Klebsiella spp and Providencia spp increased and Enterobacter spp decreased). Although E. coli was responsible for more than an half of UTI, its resistance to antibiotics was low when compared with other pathogens implicated in UTI, showing also the lowest percentage of multidrug resistant (MDR) isolates (17%). Bacteria isolated from females were less resistant than those isolated from males and this difference increased with the patient age.


The differences in sex and age must be taken in account at the moment of empirical prescription of antimicrobials. From the recommended antimicrobials by the European Association of Urology guidelines, the first line drugs (pivmecillinam and nitrofurantoin) and the alternative antibiotic amoxicillin-clavulanic acid (AMX-CLA) are appropriate to treat community-acquired UTI, but the fluoroquinolones should not be suitable to treat male infections and the trimethoprim-sulfamethoxazole (SXT) shall not be used in the treatment of UTI at this level.


Community-acquired urinary tract infection, Uropathogens, Antibiotics, Antimicrobial resistance, Multidrug resistance


The clinical laboratories have an important role in helping to manage the antibiotic use. However, in most cases microbiological data are deposited in the informatics system without being properly analyzed. Our study showed that clinical laboratories have crucial information that can contribute and improve the therapeutic success of infectious diseases which are, in most of the cases, treated empirically as the urinary tract infections. In fact, the empirical treatment of UTI entails knowing the main bacteria responsible for UTI as well as their antimicrobial resistance pattern. Unfortunately, there are few publications with this information at community level, being the present study one of the most complete studies performed in portugal, which includes a huge amount of data concerning to ten years. According to WorldHealth Organization these local data are crucial to define standard treatment guidelines, to formulate recommendations for rational antibiotic use, to establish the best treatment for individual patients. These measures avoid the increase of antimicrobial resistance and consequently the spread of bacterial resistant strains which represents a serious worldwide public health problem.

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