Time-dependent variability of infarct size and hemispheric volume in experimental focal cerebral ischemia in the rabbit.

Studies measuring the volume of infarcted tissue and survival after pharmacologic intervention in stroke are complicated by the potential effect of survival time on infarct volume. In this study, the volume of infarcted tissue as defined by 2,3,5-triphenyltetrazolium chloride staining was determined in rabbits at 28 h, 7 days, and 3 weeks after permanent middle cerebral artery occlusion. Compared to values at 28 h, infarcted tissue volume did not change at 7 days after occlusion, but decreased significantly by three weeks after occlusion (p < 0.01). Infarcted tissue volume expressed as a percent of hemispheric volume did not significantly change at either timepoint (p < 0.08). Immunocytochemical staining for glial fibrillary acidic protein (GFAP) indicated that infarct volume changes were not due to glial infiltration. Total hemispheric volume decreased by 7 days (p < 0.01) and 3 weeks (p < 0.01) after occlusion. These results suggest that changes in hemispheric volume may confound comparison of injury volumes in animals at differing times after occlusion. In experiments where drug treatments increase survival after focal cerebral ischemia, comparisons of the absolute infarct volume may not be valid if drug-treated animals survive greater than 1 week and untreated animals do not.

Relative frequency of nosocomial pathogens at a university hospital during the decade 1980 to 1989.

BACKGROUND: We compared the relative frequency of pathogens isolated from 1985 to 1989 (N = 4358) with those isolated from 1980 to 1984 (N = 5290) in a university hospital to determine trends in the relative importance of pathogens causing nosocomial infection. METHODS: Our study was based on surveillance data prospectively obtained between 1980 and 1989 from a 600-bed university hospital. Statistically significant trends occurring from 1980 to 1984 to 1985 to 1989 were determined by chi 2 tests with Bonferroni corrections (i.e., p less than [0.05/17]). RESULTS: Overall an increased frequency of isolation occurred for Candida and other yeasts and for Haemophilus species. A decreased frequency was noted for Proteus species, non-Bacteroides anaerobes, and Serratia species. Comparison of 1985 to 1989 with 1980 to 1984 revealed that the most significant change in nosocomial pathogens was the marked increase in infections with yeast, principally Candida species. Candida and other yeast infections increased 40%, from 7.6% (rank, 5) to 10.6% (rank, 3) of all pathogens isolated. Increases, which occurred in urine, blood, and wound isolates, were especially marked among surgical patients. In addition, a significant increase was noted among blood isolates in the isolation of yeast other than Candida albicans. CONCLUSIONS: We conclude that Candida and other yeasts are being isolated increasingly as causative agents of nosocomial infection.

Transparent polyurethane film as an intravenous catheter dressing. A meta-analysis of the infection risks.

OBJECTIVE: To obtain a quantitative estimate of the impact on infectious complications of using transparent dressings with intravenous catheters. DATA SOURCES: Meta-analysis of all studies published in the English literature, including abstracts, letters, and reports that examined the primary research question of infection risks associated with transparent compared with gauze dressings for use on central and peripheral venous catheters. Studies were identified by use of the MEDLINE database using the indexing terms occlusive dressings, transparent dressings, and infection and by review of referenced bibliographies. STUDY SELECTION: Seven of the 15 studies (47%) of central venous catheters and seven of 12 studies (58%) of peripheral catheters met our inclusion criteria for analysis. All studies used a prospective cohort design, utilized hospitalized patients, and reported at least one of our defined outcomes. EXTRACTION: Data for each study were abstracted independently by three investigators. At least three studies were used in the analysis of each outcome. DATA SYNTHESIS: Applying a Mantel-Haenszel chi 2 analysis, use of transparent dressings on central venous catheters was significantly associated with an elevated relative risk (RR) of catheter tip infection (RR = 1.78; 95% confidence interval [CI], 1.38 to 2.30). Catheter-related sepsis (RR = 1.69; 95% CI, 0.97 to 2.95) and bacteremia (RR = 1.63; 95% CI, 0.76 to 3.47) were both associated with an elevated RR. Use of transparent dressings on peripheral catheters was associated with an elevated RR of catheter-tip infection (RR = 1.53; 95% CI, 1.18 to 1.99) but not phlebitis (RR = 1.02; 95% CI, 0.86 to 1.20), infiltration (RR = 1.12; 95% CI, 0.92 to 1.37), or skin colonization (RR = 0.99; 95% CI, 0.90 to 1.09). CONCLUSION: The results demonstrated a significantly increased risk of catheter-tip infection with the use of transparent compared with gauze dressings when used with either central or peripheral catheters. An increased risk of bacteremia and catheter sepsis associated with the use of transparent compared with gauze dressings for use on central venous catheters was suggested.

Disinfection practices for endoscopes and other semicritical items.

OBJECTIVE: To determine the disinfection practices employed by North Carolina hospitals for endoscopes and other semicritical patient care items and to discuss minimally acceptable disinfection procedures for these items. DESIGN: A survey questionnaire was mailed to all North Carolina hospitals to identify their disinfection practices, and a literature review was conducted to ascertain studies that evaluated disinfection techniques for certain semicritical items. PARTICIPANTS: Questionnaires were returned by 107 of 167 (64%) North Carolina acute-care hospitals. RESULTS: Most hospitals (91%) used a glutaraldehyde-based disinfectant (59%, 2% glutaraldehyde; 29%, 0.13% glutaraldehyde-0.44% phenol-0.08% phenate; 3%, either); half (51%) of the hospitals immersed the endoscope into disinfectant for greater than or equal to 20 minutes, but 44% immersed for less than or equal to 10 minutes; nearly all hospitals (97%) disinfected endoscopes at room temperature. Hospitals rinsed the endoscope with sterile water (16%), tap water (54%), tap water followed by alcohol rinse (27%), or other (2%); 58% of the hospitals treated endoscopes from patients infected with human immunodeficiency virus (HIV), hepatitis B virus (HBV), or Mycobacterium tuberculosis differently (81%, ethylene oxide [ETO] sterilization; 10%, increased exposure time; 10%, other). Twenty percent of the hospitals used an automated washer for processing endoscopic instruments. Rigid endoscopes (e.g., arthroscopes, laparoscopes) were primarily high-level disinfected (57%), ETO sterilized (17%), or either (13%). The disinfection strategies for other semi-critical items (e.g., applanation tonometers, cryosurgical instruments, and diaphragm fitting rings) were highly variable for the responding hospitals. CONCLUSIONS: This survey indicated the presence of a wide variety of practices for handling semicritical patient care items, many of which are inconsistent with current recommendations. To help establish minimally acceptable disinfection procedures for some patient care instruments (e.g., arthroscopes, laparoscopes, tonometers), the scientific literature was reviewed and recommendations were made.

Infection control strategies relevant to employee health.

A well organized employee health service is a key component of an effective infection control program. All health care providers should be immune to mumps, measles, rubella, tetanus, and polio. Hepatitis B vaccine should be offered to all workers who have contact with blood. Employees with signs and symptoms of infectious diseases should be evaluated by Employee Health and follow work restrictions. Employees with exposure to communicable diseases should be evaluated for prophylaxis.

Pseudoepidemic of Rhodotorula rubra in patients undergoing fiberoptic bronchoscopy.

Between March and June 1988, Rhodotorula rubra was isolated from the bronchial washings of 30 of 56 (54%) patients undergoing bronchoscopy at a North Carolina community hospital. Pulmonary disease consistent with invasive fungal pneumonia was not apparent for any patient. Repeat sputum cultures were performed on 11 patients, none of whom were positive for R rubra. Investigation revealed fungal contamination of two brushes used to clean the bronchoscope channels and one positive sample of the tub water used to test the integrity of the bronchoscope prior to cleaning and disinfection. Control measures instituted were high-level disinfection of all equipment used to clean the bronchoscopes, including the brushes, complete air drying of the bronchoscopes before storing and storage of equipment in closed cabinets. An additional case one month after instituting these measures prompted the addition of a final 70% ethyl alcohol rinse of the bronchoscopes immediately prior to storage. Over a six-month period no additional cases have been identified. Despite published disinfection guidelines, pseudoepidemics and infections from contaminated equipment continue to appear. This pseudoepidemic investigation revealed a site for contaminating bronchoscopes that has not been previously reported, the inner cannula cleaning brushes. This emphasizes the need for stringent adherence to recommended cleaning and disinfection guidelines.

Bacterial colonization and phlebitis-associated risk with transparent polyurethane film for peripheral intravenous site dressings.

Previous studies of various brands of polyurethane dressings have noted differences in the rates of catheter colonization. We compared Bioclusive transparent polyurethane (TP) dressing with a cotton gauze (CG) dressing on peripheral intravenous (IV) access sites for the incidence of phlebitis, catheter tip colonization, skin colonization, and catheter-related bacteremia. The study, involving 598 ward patients, was case controlled, prospective, and randomized for a period of 4 months. Each patient was entered into the study only once, and all dressings were applied by a member of the IV therapy team. No significant difference was seen for phlebitis rate (TP: 9.8% vs. CG: 7.6%) or catheter tip colonization, defined as greater than 15 colony forming units (CFU) (5.7% vs. 4.4%) by a semiquantitative technique. Cultures of specimens from the skin and catheter tips of the majority of patients (91%) showed no growth. An association was found between those patients with greater than 15 CFU isolated from catheter tips and those with phlebitis (p = 0.022). No documented catheter-related bacteremia occurred in either study group.

Associated mortality and clinical characteristics of nosocomial Pseudomonas maltophilia in a university hospital.

We studied the spectrum of clinical disease in 99 patients with nosocomial Pseudomonas maltophilia isolates at the University of Virginia Hospital from 1981 through 1984. The annual rate of isolation increased from 7.1 to 14.1 per 10,000 patient discharges. A crude mortality rate of 43% was documented in all patients from whom the organism was cultured, and the data include 12 patients with nosocomial bacteremia (four deaths). Risk factors associated with death for patients having a P. maltophilia isolate included the following: requirement for care in any intensive care unit during hospitalization (P = 0.0001), patient age over 40 years (P = 0.002), and a pulmonary source for the P. maltophilia isolate (P = 0.003). All P. maltophilia isolates were susceptible to trimethoprim-sulfamethoxazole, 60% of the isolates were resistant to all aminoglycosides (amikacin, tobramycin, and gentamicin), and more than 75% of the isolates were resistant to all beta-lactam antibiotics. The antibiotic susceptibility pattern allows for a niche exploitable in the hospital microbial environment by an organism with a marked associated mortality.