Estudio prospectivo de la infección urinaria por sondaje vesical en un hospital general universitario

Laburpena

ABSTRACT -The main aim of the research is to examine the incidence and the features of urinary infections in patients undergoing bladder catheterisation throughout hospitalisation, as well as the causes of the development of such infections. MATERIALS AND METHODS -The prospective and observational evaluation was conducted at Hospital General Universitario ``José María Morales Meseguer´´ (Murcia) between April, July and September 2011 and January and April 201. The research comprised 114 patients over eighteen years of age who were hospitalised in the Internal Medicine, General Surgery and Traumatology Services and undergoing bladder catheterisation for at least 24 hours and were willing to participate in the research. The data collection protocol included demographics, underlying medical conditions, history of antimicrobial exposure, data related to the catheterisation procedure, presence, or absence of symptoms consistent with UTI throughout hospitalisation and the evolution of the infection in case it was detected. Throughout the catheterisation, an evolutionary microbiological study of urine was conducted; three urine cultures were requested at different moments: after the initial 24 hours of catheterisation, before removing the catheter, and 48 hours after the catheter removal. In case of detection of signs or symptoms suggestive of urinary tract infections, urine culture was requested to determine the aetiological agents related to that infection. The urine cultures were processed according to the recommendations from the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC, by its acronym in Spanish). Those urine cultures with counts of 103 UFC/ml were considered positive, regardless of the number of microorganisms. The identification and study of the antibiotic sensitivity of the microorganisms were performed with the automatic Walk Away system (MicroScan, Siemens), and the results were interpreted according to the CLSI guidelines. RESULTS - 84.3% of the patients had some positive urine culture during monitoring (bacteriuria). 69.7% of surveillance urine cultures were polymicrobial, with the mean growth count of microorganisms being 57,674 UFC/ml. A total of 244 microorganisms were identified. The most frequently isolated microorganism was Enterococcus faecalis (39.47% of patients), followed by Escherichia coli (24.5%), Candida spp (15.2%), Pseudomonas aeruginosa (14.9%) and Klebsiella spp (12.2%). The percentage of patients with bacteriuria in samples obtained in the first 24 hours after catheterisation was 27%, which increased while the bladder catheter was in place. Globally, bacteriuria was more frequent in women (p<0.05). Not all microorganisms present in the urine showed the same behaviour; Enterococcus faecalis and Escherichia coli showed a clear relationship with the female sex, and their presence was not conditioned by the duration of the catheterisation, unlike Pseudomonas aeruginosa and Klebsiella spp, being their presence related to more prolonged use of bladder catheterisation. The study of antibiotic sensitivity of microorganisms isolated in urine showed that, in global terms, the rate of resistance to ciprofloxacin was 29.2% (62 resistant/212 tested), to amoxicillin-clavulanate 38.2% (39/102) to fosfomycin 16.5% (35/211) and to trimethoprim/sulfamethoxazole 28.8% (30/104). The global resistance to cefotaxime was 29.1% (30/103) and to gentamicin 8.9% (11/123). None of the gram-negative isolates were carbapenemase producers, and no resistance to vancomycin was detected among the gram-positive bacteria. 14% of the patients included in the study developed UTI symptoms. After performing multivariate analysis, the only factors associated with the appearance of CA-UTI were more extended duration of catheterisation (9 days vs 4.5 days in non-UTI; p 0.001) and E. faecalis bacteriuria. 64.2% were monomicrobial, and 35.7% were polymicrobial with two microorganisms, E. faecalis was the accompanying microorganism in most cases. The most frequently isolated microorganisms were P. aeruginosa, E. coli, Klebsiella spp and E. faecalis. The evolution of patients with CA-UTI was satisfactory in most cases; only one patient died as a result of a UTI. CONCLUSION - Polymicrobial bacteriuria is a common occurrence in catheterised patients. Not all microorganisms that colonise the urine of these patients have the same behaviour, so their clinical significance must be interpreted individually, considering each patient's context. Enterococcus faecalis was the only microorganism that seems to be associated with an increased risk of developing a symptomatic urinary tract infection, forming part of polymicrobial cultures in most cases. The more extended hospitalisation, the more prolonged the duration of bladder catheterisation, and catheter manipulations (replacing or cleaning) were other factors associated with developing a CA-UTI. The role of E. faecalis as a facilitator of biofilm formation or the penetration of other microorganisms requires proper research tailored for that purpose.