Changes in the antimicrobial susceptibility of Escherichia coli isolates from community diagnosed urinary tract infections during the period 2003-2007. Multicentre study in Castilla la Mancha (Spain)

D. TENA, A. GONZÁLEZ-PRAETORIUS, J. C. GONZÁLEZ, E. HEREDERO, S. ILLESCAS, C. SAINZ DE BARANDA, G. SESEÑA

Objective: To know the evolution of susceptibility patterns of Escherichia coli in patients with communitydiagnosed urinary tract infections (UTIs) during last years in Castilla la Mancha (Spain).
Methods: Descriptive and retrospective study performed between january 2003 and december 2007. We studied data about frequency and susceptibility of 33.651 E. coli isolates from urine cultures that were remited from primary care centres depending of 6 hospitals in Castilla la Mancha (Spain).
Results: Susceptibility rates of E. coli for most antibiotics decreased significantly during the 5-year period, especially for amoxicillin-clavulanic acid, cefuroxime and quinolones. Average rates of susceptibility for amoxicillin- clavulanic acid, ciprofloxacin, cefuroxime, fosfomycin and nitrofurantoin were: 86,7, 75,4, 87,3, 97,6 and 96,2%, respectively. We observed a significantly increase of E. coli isolates producing extended-spectrum betalactamases (ESBLs), from 1,9% in 2003 to 4,9% in 2007 (χ2 TL = 143,6, p<0,001).
Conclusions: We observed a significantly reduction of E. coli susceptibility for most antibiotics and an increase of E. coli isolates producing ESBLs. Fosfomycin and nitrofurantoin are the best choices for empiric treatment. Prospective studies should be performed in the future to confirm the results of our study.

 
Rev Esp Quimioter 2010:23(1):36-42 [pdf]

Evaluation of pharmacodynamic target attainment with vancomycin treatment of bacteremia due to Staphylococcus aureus methicillin resistant

J. A. LEPE, M. V. GIL-NAVARRO, M. D. SANTOS-RUBIO, J. BAUTISTA, J. AZNAR

Objective: The objective of the study is to evaluate the ability of standard vancomycin dosing strategies actually recommended to attain the pharmacodynamic target of an area under the curve of vancomycin serum concentration versus time from 0 to 24 hours (AUC24h) to minimum inhibitory concentration (MIC) ratio greater than 400:1 for patients with a suspected or documented methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia by individual analysis and Monte Carlo simulation.
Material and methods: The study included all patients admitted with suspected or proven MRSA infection during the years 2007-2008, and who were initially treated with vancomycin at a dose of 30 mg/kg/day, and underwent pharmacokinetic monitoring. The area under the curve of vancomycin serum concentration versus time from 0 to 24 hours (AUC24h) was calculated as daily dose/clearance total (D24h/CL). Additionally, we studied 45 isolates of MRSA obtained from blood cultures in the period 2007-2008. The MIC to vancomycin was determined using Epsilon-test®. The PK-PD parameter calculated was AUC24h/MIC. Microsoft
Excel was used to perform a 10.000 subject Monte Carlo simulation. An AUC24h/MIC ≥ 400 was assumed as the target attainment.
Results: In the individual study, the percentage of patients with AUC24h/MIC50/90 ≥ 400 was 50%. The probability (%) of attaining AUC24h/MIC ratio values ≥ 400 by Monte Carlo simulation was of 66%. The vancomycin MIC value from which the scenario would have to wait a suboptimal treatment (target <90%) was >1 mg/L.
Discussion: This study shows that in the population studied to achieve a vancomycin AUC24h/MIC ≥ 400 is not always attained with the standard dose. Therefore, one would expect a high probability of suboptimal vancomycin AUC24h/MIC ratios for patients infected with organisms with vancomycin MICs of >1 mg/L treated with doses of 30 mg/kg/day.

 
Rev Esp Quimioter 2010:23(1):43-47 [pdf]

Differences in the use of tigecycline between ICU patients and non-ICU patients

F. ALVÁREZ-LERMA, L. BLANCO, J.A. RODRÍGUEZ, S. GRAU, D. CONDE-ESTÉVEZ, S. LUQUE

Background. Tigecycline is a new broad spectrum antibiotic that is predominantly used for the treatment of severe infections both in critically ill patients admitted to the ICU and in non-ICU patients with less severe clinical conditions.
Objetive. To assess differences in the use of tigecycline between ICU patients and non-ICU patients treated with this antibiotics.
Materials and methods. Retrospective, cohort, observational study in which cases were defined as patients who received one or more doses of tigecycline over the first 18 months after approval of the drug in a general hospital. Clinical characteristics, indications, route of administration, clinical response, tolerability and outcome were recorded in the groups of ICU and non-ICU patients. Descriptive data and results of the comparison of both cohorts are presented.
Results. A total of 103 were included in the study, 34 (33%) of which received tigecycline during their stay in the ICU. ICU patients compared to non-ICU patients had a higher SAPS II score on admission (39.0 ± 11.8 vs 26.3 ± 8.0, p < 0.001) and at the time of starting tigecycline treatment (42.2 ± 12.6 vs 25.6 ± 8.2, p < 0.001), were treated with antibiotics for more days (21.4 ± 30.6 vs 13.6 ± 30.5 days, p < 0.012) and received a greater number of antibiotic agents concomitantly (85.3% vs 47.8%,p < 0.001), presented a higher selection of emerging bacterial flora (41.2% vs 15.9%, p = 0.005), particularly Pseudomonas aeruginosa (20.6% vs 2.9%, p = 0.006), higher rate of clinical failure (58.8% vs 21.7%, p < 0.001), longer hospitalization (51.2 ± 39.4 vs 28.7 ± 26.3 days, p < 0.001) and higher overall mortality rate (50% vs 14.5%, p < 0.001) and infection-attributed mortality (20.6% vs 7.2%, p = 0.047).
Conclusions. The patient that receives tigecycline in the ICU has a higher severity level and worse clinical outcome than the non-ICU patient treated with this antibiotic. It is necessary to optimize the indications of tigecycline in the ICU to improve the clinical results.

 
Rev Esp Quimioter 2010:23(2):63-71 [pdf]

The microbiologist and the catheter related infection

J. GARCÍA-RODRÍGUEZ, M. DE PABLOS, A. GUTIÉRREZ

Different multicentre epidemiological studies such as ENVIN-HELICS or EPINE, have remarked that catheter related bloodstream infection (CRBI) is an increasingly condition in hospital environment. The microbiologist plays a major role in the diagnosis, either by recommending what type of catheter must be considered for confirmatory diagnosis, when these samples must be sent for culture, when is indicated to perform surveillance studies of the catheter and what results are clinically significant to be informed. In this paper, differentaspects of the CRBI, such as the pathogenesis, etiology, epidemiology and diagnosis are reviewed. The different microbiological diagnostic methods, both conservatives and those involving the removal of the catheter are up-to-dated.

 
Rev Esp Quimioter 2010:23(2):53-62 [pdf]