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Biomedical subjects

B M Farr

Publications and source records attributed to B M Farr.

At least 55 records · Page 3Linked to original sources

Preventing pneumococcal bacteremia in patients at risk. Results of a matched case-control study.

BACKGROUND: Three randomized controlled trials of the effectiveness of pneumococcal vaccine in elderly and chronically ill adults in the United States have failed to show significant protective efficacy during 44,213 person-years of follow-up. Case-control studies have greater statistical power to detect significant prevention of rare diseases such as pneumococcal bacteremia, but they also have a greater susceptibility to bias, necessitating consistent results from multiple studies. Three case-control studies at two different universities have shown prevention of systemic infection, but another study found no benefit. METHODS: Patients with pneumococcal bacteremia who were at least 2 years old and had chronic illness indicating the need for pneumococcal vaccine, or who were at least 65 years old were compared with matched control subjects for frequency of prior vaccination. Matching variables included date of admission, age, sex, race, type and duration of chronic illness serving as the major vaccine indication, number of vaccine indications and number of medical hospitalizations since licensure of the pneumococcal vaccine in 1978, and type of primary medical care. RESULTS: Pneumococcal vaccination was documented in the records of six (7%) of 85 cases and 26 (17%) of 152 control subjects, suggesting 81% efficacy in conditional logistical regression analysis (95% confidence interval, 34% to 94%, P = .008). CONCLUSIONS: Four case-control studies at three universities have now demonstrated significant protective efficacy of pneumococcal vaccine for preventing pneumococcal bacteremia. The development of antibiotic-resistant Streptococcus pneumoniae indicates an urgent need for an increased rate of vaccination among high-risk patients and for the development of more immunogenic conjugate vaccines that may enhance efficacy among elderly and immunocompromised patients as well as infants.

Adolescent↗

Risk factors for infection of adult patients with cancer who have tunnelled central venous catheters.

BACKGROUND: Long-dwelling tunnelled central venous catheters provide reliable access for infusion therapy of patients with cancer, but can result in serious bloodstream infections. The incidence of such infections has been documented, but few studies have assessed potential risk factors, and to the authors' knowledge, none have measured the effect of neutropenia upon the incidence of these infections. METHODS: A cohort of 71 adult patients with cancer with long-dwelling tunnelled central venous catheters was followed for a total of 12,410 catheter days until catheter removal, death, or end of study for the occurrence of catheter-related infection or sepsis of unknown origin. Fifteen factors were assessed for association with these infections. RESULTS: Thirteen patients (18%) experienced a catheter-related infection (1.0/1000 catheter days), and 23 (32%) experienced sepsis of unknown origin. Neutropenia was associated significantly with risk for catheter-related infection (relative risk [RR] = 15.1, 95% confidence interval [CI] 2.7-86.9) and sepsis of unknown origin (RR = 10.3, 95% CI 4.0-26.8). Inpatient status, acute leukemia, and cytosine arabinoside therapy also were associated with sepsis of unknown origin, but not when adjusted for neutropenia. CONCLUSION: Of the 15 potential risk factors studied, neutropenia was the only independent risk factor for infection related to long-dwelling tunnelled central venous catheters and for sepsis of unknown origin.

Adult↗

Central venous catheter practices: results of a survey.

BACKGROUND: The incidence of nosocomial bloodstream infections has increased twofold to threefold in the past decade, and central venous catheter infections account for about 90% of catheter-related nosocomial bloodstream infections. Many studies of risk factors for central venous catheter complications have been conducted, resulting in recommendations for preventive strategies, but few data are available regarding the frequency with which such strategies are employed in clinical practice. METHODS: A survey was conducted of persons attending a meeting of the National Association of Vascular Access Networks in New Orleans on September 25, 1992. The survey contained 15 questions related to central venous catheters regarding infection control measures, measures to maintain patency, and use of the catheter for obtaining blood specimens for diagnostic tests. RESULTS: Ninety-two persons from 24 states completed the questionnaire as representatives of 23 teaching hospitals, 21 nonteaching hospitals, and 48 home health agencies. Transparent dressings were used more frequently (88%) than cotton gauze (27%). Alcohol and povidone-iodine solutions were the most frequently used antiseptics. Antimicrobial ointment was used by fewer than half; of these 86% used povidone-iodine and 26% used polymyxin-neomycin-bacitracin. Heparin flushes were still being used by 97% to maintain patency. Most (82%) used central venous catheters to draw blood cultures; of these, 68% drew only qualitative cultures and 32% drew quantitative cultures in addition to or instead of qualitative cultures. CONCLUSIONS: Significant diversity of practice was documented among the health care organizations represented in this survey. Some of the practices documented in this survey have been associated with higher rates of bloodstream infection; this may partially explain the observed increase during the past decade in the incidence of nosocomial bloodstream infections.

Anti-Infective Agents, Local↗

An outbreak of needlestick injuries in hospital employees due to needles piercing infectious waste containers.

OBJECTIVES: To investigate the cause of an outbreak of needlestick injuries (NSIs) in hospital employees. SETTING: A 700-bed university hospital. DESIGN: Outbreak investigation, laboratory evaluation of a medical waste disposal device, cost analysis. METHODS: Employee health department records were reviewed of workers suffering sticks from needles piercing fiberboard-contaminated material containers (CMCs). A laboratory evaluation of needle-puncture resistance properties of the CMCs was performed using a testing apparatus. The cost of a hospital waste disposal program using fiberboard CMCs was compared with the cost of a program using rigid plastic (polypropylene) boxes. RESULTS: During 40 months of surveillance in 1986 and from 1989 to 1991, only one NSI had occurred from a needle piercing a CMC. During 9 months in 1993, 13 NSIs occurred due to needles piercing CMCs (P < .001). No clinical illness resulted from the NSIs. The outbreak was halted by a temporary change to plastic (polypropylene) boxes for sharps disposal ($4.92 to $23.33/cu ft) until receipt of a box with a newly designed solid fiberboard liner ($1.25/cu ft). CMC liners used during the epidemic had a mean needle puncture resistance of 527 g, as compared with 660 g for liners used before the outbreak (P < .001). The new solid fiberboard liner has a mean puncture resistance of 1,765 g. A program of waste disposal using fiberboard CMCs was found to cost approximately one-seventh the cost of a program using plastic boxes for disposal of infectious waste. CONCLUSION: A program for infectious waste disposal using fiberboard CMCs can be safe and cost-effective if appropriate standards for puncture resistance are met.

Containment of Biohazards↗

Control of methicillin-resistant Staphylococcus aureus at a university hospital: one decade later.

OBJECTIVE: To investigate the cause of increasing rates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection at a university hospital. DESIGN: Review of data collected by prospective hospital wide surveillance regarding rates of nosocomial MRSA colonization and infection. SETTING: A 700-bed university hospital providing primary and tertiary care. PATIENTS: Patients admitted to the hospital between 1986 and 1993 who were found to be infected or colonized with MRSA. MAIN OUTCOME MEASUREMENT: Rates of MRSA infection and colonization. RESULTS: MRSA infection or colonization was identified in 399 patients (0.18%) admitted during the 8-year study. There was no correlation between the annual rates of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infections (P = .66). The frequency of both nosocomial and non-nosocomial cases increased significantly over the last 4 years of the study (P < .001 for trend). The ratio of patients who had acquired MRSA nosocomially to those admitted who already were infected or colonized decreased significantly during the study period (P = .002 for trend). There was a significant increase in the frequency of patients with MRSA being transferred from nursing homes and other chronic care facilities (P = .011). A cost-benefit analysis suggested that surveillance cultures of patients transferred from other healthcare facilities would save between $20,062 and $462,067 and prevent from 8 to 41 nosocomial infections. CONCLUSIONS: An increase in the incidence of nosocomial MRSA infection was associated with an increased frequency of transfer of colonized patients from nursing homes and other hospitals. The lack of correlation between rates of MRSA and MSSA infections suggested that MRSA infections significantly increased the overall rate of staphylococcal infection. Screening cultures of transfer patients from facilities with a high prevalence of MRSA may offer significant benefit by preventing nosocomial infections and reducing patient days spent in isolation.

Cost-Benefit Analysis↗

Vascular catheter related infections in cancer patients.

Immunocompromise due to malignancy or to cytotoxic chemotherapy with resulting neutropenia creates a high risk of infection among cancer patients. The frequent presence of long-dwelling vascular catheters in these patients adds to this risk. Recent data regarding the epidemiology, diagnosis, management, and prevention of vascular catheter related infections are discussed.

Catheters, Indwelling↗

Does pseudoephedrine increase blood pressure in patients with controlled hypertension?

BACKGROUND: The use of the decongestant pseudoephedrine has been avoided in hypertensive patients with little evidence to support this caution. The purpose of this study was to determine the effects of therapeutic doses of pseudoephedrine on blood pressure in patients with controlled hypertension. METHODS: Twenty-five patients with controlled hypertension were enrolled in a randomized, placebo-controlled, double-blind crossover trial. This was a 4-week study in which all participants received placebo during the 1st and 3rd weeks. Subjects were randomly assigned to receive pseudoephedrine or placebo during the 2nd week of the study, and to receive the opposite during the 4th week of the study. Blood pressure readings were taken at the beginning and end of each week of the trial, and at a 1-week poststudy follow-up visit. RESULTS: The mean systolic pressure was 133 mm Hg in patients receiving both pseudoephedrine and placebo (P = NS). The mean diastolic pressure was 82 mm Hg in patients receiving pseudoephedrine and 82.5 mm Hg in patients receiving placebo. Mean pulse rates were 76.8 and 75.2 beats per minute in patients given pseudoephedrine and those given placebo, respectively (P = NS). There were no statistically significant or clinically important differences in the mean systolic or mean diastolic blood pressures among the groups during the entire 4-week course of the study. CONCLUSIONS: At standard doses, pseudoephedrine has no significant effect on systolic or diastolic blood pressure in patients with controlled hypertension.

Adult↗

The use of high-efficiency particulate air-filter respirators to protect hospital workers from tuberculosis. A cost-effectiveness analysis.

BACKGROUND: After outbreaks of multidrug-resistant tuberculosis, the Centers for Disease Control and Prevention proposed the use of respirators with high-efficiency particulate air filters (HEPA respirators) as part of isolation precautions against tuberculosis, along with a respiratory-protection program for health care workers that includes medical evaluation, training, and tests of the fit of the respirators. Each HEPA respirator costs between $7.51 and $9.08, about 10 times the cost of respirators currently used. METHODS: We conducted a cost-effectiveness analysis using data from the University of Virginia Hospital on exposure to patients with tuberculosis and rates at which the purified-protein-derivative (PPD) skin test became positive in hospital workers. The costs of a respiratory-protection program were based on those of an existing program for workers dealing with hazardous substances. RESULTS: During 1992, 11 patients with documented tuberculosis were admitted to our hospital. Eight of 3852 workers (0.2 percent) had PPD tests that became positive. Five of these conversions were believed to be due to the booster phenomenon; one followed unprotected exposure to a patient not yet in isolation; the other two occurred in workers who had never entered a tuberculosis isolation room. These data suggest that it will take more than one year for the use of HEPA respirators to prevent a single conversion of the PPD test. Assuming that one conversion is prevented per year, however, it would take 41 years at out hospital to prevent one case of occupationally acquired tuberculosis, at a cost of $1.3 million to $18.5 million. CONCLUSIONS: Given the effectiveness of currently recommended measures to prevent nosocomial transmission of tuberculosis, the addition of HEPA respirators would offer negligible protective efficacy at great cost.

Cost-Benefit Analysis↗

Mycobacterium tuberculosis transmission rates in a sanatorium: implications for new preventive guidelines.

BACKGROUND: In 1990, the Centers for Disease Control and Prevention recommended substituting dust-mist particulate respirators for simple isolation masks in acid-fast bacillus isolation rooms, reasoning that air leaks around the simple masks could result in a higher rate of purified protein derivative skin-test conversion. In 1993, a Centers for Disease Control and Prevention draft guideline proposed that high-efficiency particulate air filter respirators be used instead of dust-mist particulate respirators. Epidemiologic data were not available to assess the importance of these changes or their cost-effectiveness. METHODS: The University of Virginia was affiliated with a tuberculosis hospital from 1979 until 1987. We surveyed physicians who had served as residents in internal medicine during this period regarding purified protein derivative skin-test history. duration of work at the tuberculosis sanatorium, and any history of unprotected exposures to patients with active pulmonary or laryngeal tuberculosis. Patients with active tuberculosis at the sanatorium were isolated in negative-pressure rooms with UV lights. Physicians wore simple isolation masks in these rooms. RESULTS: Responses were received from 83 former resident physicians. Fifty-two physicians had worked on the tuberculosis wards for a total of 420 weeks, with no subsequent skin-test conversions (95% CI 0 to 1 conversion/8 physician-years). CONCLUSIONS: These data document a low risk of occupational transmission of Mycobacterium tuberculosis to physicians who wear simple isolation masks in negative-pressure ventilation rooms with UV lights. This low rate predicts that the additional protective efficacy and cost-effectiveness of the more expensive high-efficiency particulate air filter respirators and the respiratory protection program will be low.

Hospitals, Special↗

Short-course therapy of catheter-related Staphylococcus aureus bacteremia: a meta-analysis.

OBJECTIVE: To determine, through structured methodologic review of published articles, the effectiveness of short-course (< or = 2 weeks) antibiotic therapy for catheter-related Staphylococcus aureus bacteremia. DATA SOURCES: English-language publications on catheter-related S. aureus bacteremia identified using MEDLINE (1966 to the present) and bibliographic review of relevant articles and textbooks. STUDY SELECTION: Any study reporting outcome data for patients with catheter-related S. aureus bacteremia who were treated with short-course therapy. DATA EXTRACTION: Epidemiologic criteria were applied to assess the quality of protection provided by each study against four important types of biases. In addition, the statistical precision of each study was assessed. DATA SYNTHESIS: Eleven studies were identified. Reported late complication rates varied from 0% to 29%; the pooled estimate of the late complication rate was 6.1% (95% Cl, 2.0% to 10.2%). Ten of the 11 studies were uncontrolled. Only three provided adequate protection against treatment allocation bias. None of the studies adequately defined the illness under study, and only four provided adequate follow-up. The relapse rates in all 11 studies had low statistical precision. The complication and mortality rates for catheter-related S. aureus bacteremia when published data were pooled, regardless of duration of therapy, were 24% and 15%, respectively. CONCLUSIONS: The available data regarding the safety of short-course therapy for catheter-related S. aureus bacteremia are potentially flawed by both bias and statistical imprecision. The optimal duration of treatment remains unknown. Short-course therapy should be viewed with caution in treating this serious infection until randomized trials determine the comparative rates of late complication.

Anti-Bacterial Agents↗

Selective surveillance for nosocomial infections in a Brazilian hospital.

OBJECTIVE: To devise a system for surveying the frequency of nosocomial infections in a tertiary care hospital in a developing country. DESIGN: Prospective selective surveillance by nurses of the charts of patients at high risk for nosocomial infections, as identified by a form completed by resident physicians. The sensitivity, specificity, and predictive value of this method of selective surveillance were compared with those for total prospective chart review by two infectious disease specialists. SETTING: A university hospital in northeastern Brazil. PATIENTS: All patients hospitalized for more than 72 hours with an identified risk factor for nosocomial infection. RESULTS: The ratio of nosocomial infections to 100 discharges was 13.4 and the incidence density was 11.2/1,000 patient days. The surveillance method demonstrated a sensitivity of 74% and a specificity of 99.7%. Positive predictive value was 93%, negative predictive value was 99%, and overall accuracy was 98%. CONCLUSIONS: This method of selective surveillance for nosocomial infections based on risk factors identified by physicians demonstrated excellent predictive value and overall accuracy and may be of use to other hospitals that lack a nursing care plan book such as the Kardex. The relative frequency of nosocomial infections significantly exceeded the rates reported from hospitals in developed countries.

Brazil↗

Adenovirus type 8 epidemic keratoconjunctivitis in an eye clinic: risk factors and control.

Epidemic keratoconjunctivitis (EKC) due to adenovirus type 8 affected 126 (7%) of 1870 ophthalmology clinic patients during an outbreak. Risk factors and mode of transmission were studied by comparing cases (n = 58) and controls (n = 200) for exposure to risk factors. Pneumotonometry (odds ratio [OR], 10.5; 95% confidence interval [CI], 4.0-27.7), multiple clinic visits (OR, 5.9; 95% CI, 3.3-10.6), and contact with an infected physician (OR, 3.3; 95% CI, 1.2-9.0) were significant risk factors for infection. The hands of 3 patients and 3 physicians with EKC were cultured before and after hand washing to assess adenovirus removal; 3 had hand cultures positive for adenovirus after hand washing. In conclusion, this outbreak appeared to be due to inadequate disinfection of instruments, especially pneumotonometers, and finger-to-eye transmission by health care workers. Hand washing did not reliably remove adenovirus from contaminated fingers. Gloving for exam of eyes with EKC may help prevent transmission. Ophthalmologists with EKC were a significant risk factor for patients and should be furloughed for the duration of communicability.

Adenovirus Infections, Human↗

A controlled trial of scheduled replacement of central venous and pulmonary-artery catheters.

BACKGROUND: The incidence of infection increases with the prolonged use of central vascular catheters, but it is unclear whether changing catheters every three days, as some recommend, will reduce the rate of infection, It is also unclear whether it is safer to change a catheter over a guide wire or insert it at a new site. METHODS: We conducted a controlled trial in adult patients in intensive care units who required central venous or pulmonary-artery catheters for more than three days. Patients were assigned randomly to undergo one of four methods of catheter exchange: replacement every three days either by insertion at a new site (group 1) or by exchange over a guide wire (group 2), or replacement when clinically indicated either by insertion at a new site (group 3) or by exchange over a guide wire (group 4). RESULTS: Of the 160 patients, 5 percent had catheter-related bloodstream infections, 16 percent had catheters that became colonized, and 9 percent had major mechanical complications. The incidence rates (per 1000 days of catheter use) of bloodstream infection were 3 in group 1, 6 in group 2, 2 in group 3, and 3 in group 4; the incidence rates of mechanical complications were 14, 4, 8, and 3, respectively. Patients randomly assigned to guide-wire-assisted exchange were more likely to have bloodstream infection after the first three days of catheterization (6 percent vs. 0, P = 0.06). Insertions at new sites were associated with more mechanical complications (5 percent vs. 1 percent, P = 0.005). CONCLUSIONS: Routine replacement of central vascular catheters every three days does not prevent infection. Exchanging catheters with the use of a guide wire increases the risk of bloodstream infection, but replacement involving insertion of catheters at new sites increases the risk of mechanical complications.

Antisepsis↗

Predicting death in patients hospitalized for community-acquired pneumonia.

OBJECTIVE: To validate a previously reported discriminant rule for predicting mortality in adult patients with primary community-acquired pneumonia and to determine which factors available at hospital admission predict a fatal outcome among such patients. DESIGN: Historical cohort study. SETTING: University hospital. PATIENTS: Adults admitted to the hospital for community-acquired pneumonia. MEASUREMENTS: Using stepwise logistic regression, we analyzed prognostic factors (data available at admission and recorded in the medical record) that showed a univariate association with mortality. The predictive values of three discriminant rules were measured to validate the results of a previous study. MAIN RESULTS: Of 245 patients, 20 (8.2%) died. Of 42 prognostic factors identified in previous studies, 8 were associated with mortality, but only a respiratory rate of 30/min or more, a diastolic blood pressure of 60 mm Hg or less, and a blood urea nitrogen of more than 7 mmol/L remained predictive in the multivariate analysis. A discriminant rule composed of these three variables was 70% sensitive and 84% specific in predicting mortality, yielding an overall accuracy of 82%. CONCLUSION: Tachypnea, diastolic hypotension, and an elevated blood urea nitrogen were independently associated with death from pneumonia in our study, confirming the value of a previously reported discriminant rule from the British Thoracic Society. This rule may be useful in triage decisions because it identifies high-risk patients who may benefit from special medical attention.

Adolescent↗

A retrospective cohort study of nosocomial diarrhea as a risk factor for nosocomial infection.

Because most nosocomial infections are caused by enteric flora, it was undertaken to determine whether diarrhea predisposes to nosocomial infections by conducting a retrospective cohort study involving patients with and without nosocomial diarrhea who were hospitalized during a 12-month period. The rate of urinary tract infection per person-day after onset of diarrhea was significantly greater in patients with diarrhea (relative risk = 10.3; 95% confidence interval = 1.7-63.1, P = .006). When indwelling bladder catheter and duration of catheter placement were considered, diarrhea remained an independent risk factor for urinary tract infection in logistic regression analysis (P = .009). These data suggest that diarrhea and consequent urethral meatal contamination may be a cause of nosocomial urinary tract infection, especially in patients with a catheter, and that removal of the catheter should be considered whenever possible in patients with diarrhea.

Adolescent↗