Impact of an antibiotic restriction program on antibiotic utilization in the treatment of community-acquired pneumonia in a Veterans Affairs Medical Center.

PURPOSE: The impact of an antibiotic restriction program (ARP) on the patterns of antibiotic use in the treatment of community-acquired pneumonia (CAP) was examined. We also evaluated the association between the ARP and the length of hospital stay in regard to CAP treatment and cost savings associated with the implementation of the ARP. METHODS: A retrospective cohort study of patients admitted with CAP was conducted during two 6-month periods, one prior to the ARP and one after the ARP. The health system's computerized patient record system (CPRS) was used to obtain demographics, length of hospital stays, readmission rates, blood culture results, co-morbidities, antibiotic use, and durations of therapy. A total of 130 patients met the inclusion criteria for the final analyses. Average drug costs, employee salaries, and the cost of laboratory procedures were used to assess cost savings associated with the ARP. RESULTS: From a total of 132 antibiotics that were ordered to treat CAP in the pre-ARP period, 28 were restricted (21.2%). However, the number of restricted antibiotics ordered was significantly reduced to 12 out of 114 (10.2%) antibiotics ordered in the post-ARP period (P = 0.024). In post-ARP implementation, the mean length of hospital stay was also significantly reduced from 7.6 to 5.8 days (P = 0.017), and although not statistically significant, the 30-day readmission rates declined from 16.9 to 6.2% (P = 0.097). The ARP was also associated with a saving of $943 per patient treated for CAP. CONCLUSIONS: In addition to a decrease in the antibiotic utilization and the mean length of hospital stay, the ARP may have yielded cost savings and reduced the readmission rates for those patients admitted and treated for CAP.

Efficacy of trypsin in enhancing assessment of bacterial colonisation of vascular catheters.

Since the number of organisms isolated from a medical device is crucial in assessing the likelihood of device-associated infection, we examined whether incubation of catheters in trypsin before sonication can increase the yield of superficially colonised vascular catheters in vitro and those removed from patients. Polyurethane and silicone catheters were individually colonised in vitro with individual clinical isolates including Staphylococcus aureus and Escherichia coli. Equal numbers of 1 cm segments of colonised catheters were then individually incubated either in a trypsin-containing solution or a control solution without trypsin. Each solution containing the segment was then sonicated and cultured quantitatively. In the clinical arm, indwelling catheters removed from patients were also cut into 1 cm segments that were equally suspended in the trypsin-containing or control solution and then sonicated and cultured quantitatively. Trypsin-based sonication enhanced the detection of S. aureus on colonised polyurethane and silicone catheters in vitro by 14- and 30-fold, respectively (P = 0.03 and P = 0.04), and the detection of E. coli on colonised polyurethane and silicone catheters by 3- and 6-fold, respectively (P = 0.04 and P = 0.05). Compared with sonication alone, trypsin followed by sonication resulted in 10% increase in the detectability of significant colonisation of indwelling catheters removed from patients and 11% increase in the mean colony counts of colonising organisms (P = 0.04). Exposure of catheters to trypsin before sonication improves the sensitivity of sonication and enhances the accuracy of assessing significant catheter colonisation.

Antifungal activity of antimicrobial-impregnated devices.

The in-vitro and in-vivo efficacy against Candida albicans and Candida krusei of devices impregnated with chlorhexidine and chloroxylenol was examined. The impregnated devices produced large zones of inhibition against both organisms (mean size, 39 mm and 38 mm, respectively). In a rabbit model in which segments of silicone catheters were placed percutaneously, non-impregnated devices were twice as likely as impregnated devices to become colonised with either C. albicans or C. krusei. Impregnated devices also had significantly lower colony counts of C. albicans (58 vs. 1361 CFU; p 0.008) and C. krusei (19 vs. 764 CFU; p 0.008).

Dalbavancin compared with vancomycin for prevention of Staphylococcus aureus colonization of devices in vivo.

OBJECTIVES: Although active against free-floating bacteria, vancomycin displays a poor activity against organisms embedded within the biofilm surrounding implanted devices. Dalbavancin is a novel glycopeptide antibiotic with strong activity against staphylococci and a long half-life that allows for once-a-week dosing. The objective of this animal study was to examine the ability of dalbavancin and vancomycin to prevent Staphylococcus aureus colonization of devices. METHODS: Twelve rabbits were randomized, in three groups of four each, to receive intravenous injections of dalbavancin, vancomycin or normal saline (control). Eight polyurethane catheter segments were subcutaneously implanted in the back of each rabbit, then inoculated with S. aureus. Rabbits were sacrificed a week later and explanted devices were cultured. RESULTS: The rates of device colonization were comparable in the vancomycin (53%) and control (47%) groups, whereas only 28% of devices in the dalbavancin group became colonized. There was a trend (although not statistically significant) toward a lower rate of device colonization following receipt of dalbavancin vs. vancomycin (P = 0.07) or saline (P = 0.02). CONCLUSIONS: The demonstrated efficacy of dalbavancin in this animal study suggest that this novel antibiotic may have an important role in the prevention and treatment of device-related infection.

Antimicrobial activity of antiseptic-coated orthopaedic devices.

Antimicrobial coating of medical devices, including fracture fixation devices, has evolved as a potentially effective method for preventing device-related infections. We examined the in vitro antimicrobial activity of titanium cylinders coated with the antiseptic combination of chlorhexidine and chloroxylenol. The coated devices provided zones of inhibition against Staphylococcus epidermidis, S. aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans, at baseline and up to 8 weeks after incubation of the coated cylinders in human serum at 37 degrees C. This durable antimicrobial activity was attributed to the relatively slow leaching of chlorhexidine and chloroxylenol from the coated cylinders as measured by high-performance liquid chromatography. These results suggest that antiseptic-coated orthopaedic devices may provide broad-spectrum and durable antimicrobial protection against device-related infection.

Identification of a Klebsiella pneumoniae strain associated with nosocomial urinary tract infection.

To differentiate between relapse of infection and reinfection of the urinary tract due to Klebsiella pneumoniae, 33 K. pneumoniae isolates collected from 20 patients with spinal cord injury (SCI) over 2 years were typed by genomic fingerprinting by repetitive-element PCR. Clinical isolates obtained from the same patients with recurrent episodes of urinary tract infection (UTI) revealed identical genomic fingerprints indicating relapse of UTI due to K. pneumoniae, despite appropriate antibiotic therapy. Seventeen isolates obtained from 8 of the 20 SCI patients shared a common genotype, termed RD6. Among non-SCI patients residing in other nursing units, the RD6 genotype was found in 5 of 10 patients with K. pneumoniae UTI but in only 1 of 20 patients with K. pneumoniae infection that did not involve the urinary tract, suggesting a strong association of this genotype with UTI. All RD6 isolates exhibited strong adherence (> or =50 adherent bacteria per cell) to HEp-2 cells, whereas other K. pneumoniae isolates generally did not adhere to or adhered very weakly to HEp-2 cells (< or =5 adherent bacteria per cell). Adherence was inhibited either by 4% D-mannose or by anti-type 1 fimbrial rabbit serum. These results suggest that the capacity of K. pneumoniae RD6 isolates to cause UTI may be mediated by its striking adherence to mammalian cells.