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

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.

Effect of hospitalization on the antibiotic resistance of fecal Enterococcus faecalis of surgical patients over time.

The prevalence of antibiotic resistant Enterococcus faecalis was determined in fecal samples of 263 patients admitted to the surgical wards of three university-affiliated hospitals on admission, at discharge, and at 1 and 6 months after discharge. A slight increase in the prevalence of antibiotic resistance of E. faecalis was found at discharge for the antibiotics tested compared to those on admission, vancomycin excepted. At 6 months after discharge, the prevalence of resistance for amoxicillin (0%), ciprofloxacin (3%), erythromycin (47%), and oxytetracycline (60%) decreased to the level on admission (respectively 0%, 8%, 45%, and 64%). Gentamicin resistance was the same at discharge (10%) as 1 month later (12%), but decreased 6 months after discharge (8%) to the level on admission (7%). In conclusion, hospitalization resulted in the study population in a slight increase in the prevalence of resistant fecal E. faecalis isolates at discharge, which decreased again (slowly) to the level on admission 6 months after discharge. Thus, the influence of hospitalization on the prevalence of antibiotic resistance in the extramural situation disappears between 1 and 6 months after discharge in this population.

Antibiotic usage and resistance in different regions of the Dutch community.

Regional differences of antibiotic use and antibiotic resistance in the fecal indicator bacteria Escherichia coli and enterococci were determined in different cities in the south, west, and north of The Netherlands. In 1999, differences in antibiotic consumption were observed between the different regions: 11.19, 10.84, and 7.16 DDD (defined daily dosage) per 1,000 inhabitants per day, respectively. No significant regional differences were found in the prevalence of antibiotic resistance for both E. coli and enterococci. However, the differences in antibiotic consumption observed might lead to changes in antibiotic resistance in the near future. Surveillance of antibiotic use and antibiotic resistance is strongly recommended to control the development of antibiotic resistance because it provides epidemiological data to set up and control antibiotic guidelines.

Comparative evaluation of three chromogenic agars for detection and rapid identification of aerobic Gram-negative bacteria in the normal intestinal microflora.

OBJECTIVE: To compare three different chromogenic agars and MacConkey agar for the detection of aerobic Gram-negative bacteria in the normal intestinal microflora and to assess the accuracy of the chromogenic agars for the direct identification of Escherichia coli. METHODS: A total of 164 Gram-negative clinical isolates (E. coli, Proteus, Klebsiella, Enterobacter, Morganella and Pseudomonas species) and 30 stool specimens were inoculated in parallel on four media: Chromagar E. coli/Coliform, Chromogenic urinary tract infection UTI medium, CHROMagar Orientation and MacConkey agar. All colonies that differed by color and/or morphology were selected for further identification by VITEK 1 and/or API 20E from each medium. RESULTS: On E. coli/Coliform agar five out of 32 (16%) E. coli strains failed to produce the color as described by the manufacturer. No remarkable discrepancies were found for the other clinical isolates. There was no significant difference in detection rate (DR) of aerobic Gram-negative bacteria in stool specimens between the different chromogenic agars and MacConkey agar. The overall DR was about 84%, and varied from 100% for monomicrobial specimens to 33% for polymicrobial specimens. The positive predictive values (PPV) for the direct identification of E. coli on Chromagar E. coli/Coliform, Chromogenic UTI medium and CHROMagar Orientation were 1.00, 0.93 and 0.93, respectively. The negative predictive values (NPV) were 0.53, 0.68 and 0.69, respectively. CONCLUSION: Chromogenic UTI medium and CHROMagar Orientation are the preferred media because of the higher NPV. The high PPV of these agars allows accurate and rapid identification of E. coli.

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

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.

An additional measure for quantifying antibiotic use in hospitals.

OBJECTIVES: The number of defined daily doses (DDD) per 100 patient days is often used as an indicator for the selection pressure exerted by antibiotics in the hospital setting. However, this unit of measurement does not fully describe the selection pressure and is sensitive to changes in hospital resource indicators. Additional information is required to facilitate interpretation of this indicator. The number of DDD per 100 admissions could be a valuable additional tool. The aim of this study is to investigate the importance of units of measurement in quantifying antibiotic use data with regards to antibiotic resistance risks. PATIENTS AND METHODS: Trends in antibiotic use in acute care Dutch hospitals between 1997-2001 were studied. Antibiotic use was expressed in DDD per 100 patient days and in DDD per 100 admissions. RESULTS: From 1997 to 2001, total systemic antibiotic use significantly increased from 47.2 to 54.7 DDD per 100 patient days, whereas expressed in DDD per 100 admissions it remained constant. Some individual antibiotics increases in DDD per 100 patient days were not accompanied by increases in DDD per 100 admissions and vice versa. The mean number of total DDD per hospital decreased (not significantly) between 1997 and 2001. The mean number of patient days, admissions and length of stay decreased significantly. CONCLUSIONS: Knowledge of variation in resource indicators and additional expression of the data in DDD per 100 admissions is imperative for a meaningful understanding of observed trends in antibiotic use expressed in DDD per 100 patient days. Further research is needed to determine the correlation between different measures of antibiotic use and the level of antibiotic resistance.

Hospitalization, a risk factor for antibiotic-resistant Escherichia coli in the community?

OBJECTIVE: The impact of hospitalization on the prevalence of resistant Escherichia coli in the intestinal flora of patients admitted to the surgical wards of three Dutch university-affiliated hospitals was analysed prospectively. METHODS: Faecal samples were obtained on admission to the hospital, at the time of discharge, and 1 and 6 months after discharge. All samples were examined for resistance to nine antibiotic agents. RESULTS: For the total patient population, no significant differences in the prevalence of resistance were observed at the different sampling intervals, except for a significant decrease in cefazolin resistance between the time of discharge and 6 months after discharge (10% to 3%, P < 0.05). This decrease was mainly observed in patients from the university hospital Maastricht (azM), in which a significant decrease from 17% to 6% was detected (P < 0.05). Moreover, despite dissimilarities in patient characteristics and the marked variations in antibiotic use, no significant differences in the prevalence of antibiotic resistance were observed between the three hospitals, except for the overall higher prevalence of cefazolin-resistant E. coli in azM patients (P < 0.05). CONCLUSION: In this study, hospitalization did not seem to have any substantial effect on the prevalence of antibiotic-resistant E. coli at the different time intervals. However, as our study population consisted of surgical patients with a relatively moderate antibiotic use, and the prevalence of antibiotic resistance was only analysed for faecal E. coli, further investigation should be encouraged, as the understanding of the interaction between different resistance reservoirs is important for directing future intervention studies.