Filius, P.M.G.

Comparison of the accuracy of disk diffusion zone diameters obtained by manual zone measurements to that by automated zone measurements to determine antimicrobial susceptibility (Article)

2008-10-01T00:00:00Z

Although a variety of techniques are available for antimicrobial susceptibility testing, disk diffusion methods remain the most widely used. We compared the accuracy of disk diffusion zone diameters as obtained by manual zone measurements in a low resource country (Indonesia) to that by automated zone measurements (Oxoid aura image system) in a high resource setting (the Netherlands) to determine susceptibility categories (sensitive, intermediate susceptible or resistant). A total of 683 isolates were studied, including 294 Staphylococcus aureus, 195 Escherichia coli and 194 other Enterobacteriaceae. Antimicrobial agents included tetracycline, oxacillin, gentamicin, erythromycin, trimethoprim/sulfamethoxazole and chloramphenicol for S. aureus and ampicillin, gentamicin, cefotaxime, ciprofloxacin, trimethoprim/sulfamethoxazole, and chloramphenicol for E. coli and other Enterobacteriaceae. Of the 4098 drug-organism combinations, overall category agreement (CA), major discrepancy (MD) and minor discrepancy (mD) between the two methods were 82.4% (3379/4098), 6.0% (244/4098) and 11.6% (475/4098), respectively. One hundred and sixty three of 244 MDs were resolved using reference broth microdilution method. Overall very major error (VME), major error (ME) and minor error (mE) of manual zone measurement were 28.8%, 45.4% and 4.9%, respectively and for the aura image system 4.9%, 16.0% and 4.9%, respectively. The results of this study indicate that the disk diffusion method with manual zone measurement in Indonesia is reliable for susceptibility testing. The use of an automated zone reader, such as the aura image system, will reduce the number of errors, and thus improve the accuracy of susceptibility test results for medically relevant bacteria.

Antibiotic use and other risk factors at hospital level for outbreaks with Clostridium difficile PCR ribotype 027 (Article)

2008-06-01T00:00:00Z

The first Dutch outbreak due to Clostridium difficile ribotype 027 was observed in mid-2005; by the end of that year, eight hospitals were affected. To study the relationship between hospital-wide antibiotic use and the incidence of 027-linked C. difficile-associated disease (CDAD) three study groups were made: group A, all eight hospitals with an 027-associated epidemic; group B, five of a total of six hospitals with occasional 027 cases, without an increase in CDAD; and group C, ten randomly selected hospitals with no reported 027 epidemics or isolated 027 cases. Quarterly data on CDAD incidences, hygiene measures and the use of fluoroquinolones, second-and third-generation cephalosporins, extended-spectrum penicillins, penicillins with beta-lactamase inhibitors, carbapenems, lincomycins and macrolides were collected for 2004 and 2005, and divided into pre-epidemic and epidemic periods. Using a multilevel Poisson regression analysis, CDAD incidence was linked to antibiotic use in the previous quarter and to certain hygiene measures. In the pre-epidemic period, the total use of the studied antibiotics was comparable between affected and unaffected hospitals. Higher use of second-generation cephalosporins, macrolides and all of the studied antibiotics were independently associated with a small increase in CDAD incidence [relative risk (95% confidence interval): 1.14 per increase of 100 defined daily doses per 10 000 bed days (1.06-1.23), 1.10 (1.01-1.19) and 1.02 (1.01-1.03), respectively]. However the effect was too small to predict which hospitals might be more prone to 027-associated outbreaks.

Antimicrobial resistance among commensal isolates of Escherichia coli and Staphylococcus aureus in the Indonesian population inside and outside hospitals (Article)

2008-01-01T00:00:00Z

The prevalence of antimicrobial resistance among the commensal microflora was examined in the Indonesian population inside and outside hospitals. A total of 3,995 individuals were screened in two major urban centers. Among Escherichia coli from rectal samples (n=3,284) the prevalence of resistance to ciprofloxacin and other classes of antibiotics was remarkably high, especially in individuals at the time of discharge from hospital. Staphylococcus aureus isolates (n=361) were often resistant to tetracycline (24.9%), but this was not associated with hospital stay. Two S. aureus isolates harbored the mecA gene. Regional differences in resistance rates exist, suggesting regional differences in selection pressure, i.e., antibiotic usage patterns. The results show that antimicrobial resistance among commensal E. coli and S. aureus has emerged in Indonesia.

Antimicrobial use and resistance in hospitalized patients (Doctoral Thesis)

2005-12-14T00:00:00Z

The general aim of the studies in this thesis was to explore the current emergence of antibiotic resistance in hospitals. This aim is addressed in two research projects. The first project concerns the optimization of surveillance of quantitative antibiotic use in hospitals. Studies are performed in which the interpretation of antibiotic use data is the main theme. One study focuses on the importance of units of measurement for a meaningful understanding of trends in antibiotic use data with regards to antibiotic resistance risks. In another study the surveillance of antibiotic use in Dutch hospitals between 1997 and 2002 is described. The final study of this part of the thesis is devoted to the identification of determinants of antibiotic use in Dutch hospitals. In the second research project, the epidemiology of colonization and resistance dynamics during and after hospitalization is assessed to identify risk factors for resistance emergence and to determine the relevance of transmission from the community into the hospitals, and vice versa. Colonization and resistance dynamics of Enterobacteriaceae, P. aeruginosa and Enterococcus species were assessed in the intestinal and oropharyngeal microflora of patients admitted to intensive care units and general wards. In the last chapter, the main findings of the studies in this thesis are discussed and some methodological issues are considered that are relevant to several studies in this thesis.

Colonization and resistance dynamics of gram-negative bacteria in patients during and after hospitalization. (Article)

2005-07-01T00:00:00Z

The colonization and resistance dynamics of aerobic gram-negative bacteria in the intestinal and oropharyngeal microfloras of patients admitted to intensive care units (ICU) and general wards were investigated during and after hospitalization. A total of 3,316 specimens were obtained from patients upon admission, once weekly during hospitalization, at discharge from the ICU, at discharge from the hospital, and 1 and 3 months after discharge from the hospital. Five colonies per specimen were selected for identification and susceptibility testing. In both patient populations, the gram-negative colonization rates in oropharyngeal specimens increased during hospitalization and did not decrease in the 3 months after discharge. In rectal specimens, colonization rates decreased during hospitalization and increased after discharge. There was a change in species distribution among the dominant microfloras during hospitalization. Klebsiella spp., Enterobacter spp., Serratia marcescens, and Pseudomonas aeruginosa were isolated more often, whereas the frequency of Escherichia coli declined. The percentage of ICU patients colonized with ampicillin- and/or cephalothin-resistant fecal E. coli was significantly increased at discharge from the hospital and did not change in the 3 months after discharge. The emergence of multidrug resistance was observed for E. coli during patient stays in the ICU. Resistance frequencies in E. coli significantly increased with the length of stay in the ICU. For the general ward population, no significant changes in resistance frequencies were found during hospitalization. From a population perspective, the risk of dissemination of resistant gram-negative bacteria into the community through hospitalized patients appears to be low for general ward patients but is noticeably higher among ICU patients.

Changes in antibiotic use in Dutch hospitals over a six-year period: 1997 to 2002 (Article)

2005-01-01T00:00:00Z

OBJECTIVE: To analyse trends in antibiotic use in Dutch hospitals over the period 1997 to 2002. METHODS: Data on the use of antibiotics and hospital resource indicators were obtained by distributing a questionnaire to all Dutch hospital pharmacies. Antibiotic use was expressed as the number of defined daily doses (DDD) per 100 patient-days and as DDD per 100 admissions. RESULTS: Between 1997 and 2002, the mean length of stay decreased by 18%. The mean number of admissions remained almost constant. Total antibiotic use significantly increased by 24%, from 47.2 in 1997 to 58.5 DDD per 100 patient-days in 2002 (p<0.01), whereas expressed as DDD per admissions it remained constant. Antibiotic use varied greatly between the hospitals. Moreover, the mean number of DDD per hospital of amoxicillin with clavulanic acid, clarithromycin, cefazolin, clindamycin and ciprofloxacin increased by 16, 38, 39, 50 and 52%, respectively. Total antibiotic use was higher in university hospitals than in general hospitals. CONCLUSIONS: Between 1997 and 2002, patients hospitalised in the Netherlands did not receive more antibiotics but, since they remained in the hospital for fewer days, the number of DDD per 100 patient-days increased. For macrolides, lincosamides and fluoroquinolones increases in both DDD per 100 patient-days and in DDD per 100 admissions were observed. It is arguable whether these trends result in an increase in selection pressure towards resistance in the hospitals. Continuous surveillance of antibiotic use and resistance is warranted to maintain efficacy and safety of antibiotic treatment.