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Biomedical subjects

D E Craven

Publications and source records attributed to D E Craven.

At least 91 records · Page 5Linked to original sources
PubMed1984

Contaminated medication nebulizers in mechanical ventilator circuits. Source of bacterial aerosols.

The contamination rates of medication nebulizers inserted into mechanical ventilator circuits were studied. Semiquantitative techniques were used to sample the reservoir fluid from in-line nebulizers during the first 24 hours after a circuit change. In the initial survey, high levels of contamination (organism concentrations above 10(3)/ml) were present in 13 (68 percent) of the 19 nebulizer reservoirs, and bacterial aerosols were produced by 10 (71 percent) of 14 nebulizers. Gram-negative bacilli were the predominant organisms isolated. Nebulizer contamination originated primarily from reflux of contaminated condensate in the ventilator circuit. When nebulizers were cleaned after each treatment, a reduced rate of contamination was found. Small bacterial aerosols (less than 3 microns in size) were produced in vitro after inoculation of nebulizers with gram-negative bacilli in concentrations isolated from in-use nebulizers. Contaminated in-line medication nebulizers generate small-particle bacterial aerosols that may increase the risk of ventilator-associated pneumonia and therefore should be cleaned or disinfected after each treatment rather than every 24 hours.

Aerosols↗
PubMed1984

Xanthogranulomatous pyelonephritis caused by methicillin-resistant Staphylococcus aureus.

Localized xanthogranulomatous pyelonephritis due to methicillin-resistant Staphylococcus aureus developed in a 41-year-old diabetic patient. She had recurrent bacteremia despite appropriate therapy with vancomycin. Nephrectomy was required for cure and clinical diagnosis. This report emphasizes differences in the clinical presentation and pathogenesis of xanthogranulomatous pyelonephritis caused by S. aureus. Compared with the common form of xanthogranulomatous pyelonephritis caused by gram-negative bacilli, the localized disease due to S. aureus probably results from hematogenous seeding and is not associated with nephrolithiasis or ureteral obstruction. Furthermore, this report indicates that xanthogranulomatous pyelonephritis may be caused by methicillin-resistant S. aureus, a rapidly emerging nosocomial pathogen.

Adult↗
PubMed1984

Pseudobacteremia traced to cross-contamination by an automated blood culture analyzer.

Twenty-three episodes of pseudobacteremia occurring over a seven-month period were traced to cross-contamination by the automated blood culture analyzer (BACTEC 460) used in the microbiology laboratory. An epidemiologic investigation of an unusual cluster of three patients with pseudobacteremia caused by oxacillin-resistant Staphylococcus aureus led to the identification of the problem. Mock trials of the blood culture procedure confirmed that the blood culture analyzer was the source of contamination. After the needle sterilizer was replaced by the manufacturer, the problem of cross-contamination abated. Contamination of sterile blood cultures by an instrument intended to identify bacteremia rapidly may lead to incorrect diagnosis, unnecessary administration of antibiotics and prolonged hospitalization. Because of the widespread use of automated blood culture analyzers in the US, physicians, microbiologists, and infection control personnel should be alert to the possibility of cross-contamination and the subtle way in which it may present.

Blood↗
PubMed1984

Serratia marcescens contamination of antiseptic soap containing triclosan: implications for nosocomial infection.

During a recent investigation in our surgical intensive care unit, we found that several bottles of the antiseptic handwashing soap, OR Scrub, were contaminated with Serratia marcescens. OR Scrub contains 1% triclosan, lanolin, and detergents. The antimicrobial efficacy of OR Scrub was examined in vitro using serial two-fold dilutions of soap inoculated with various concentrations of different nosocomial pathogens. The minimal bactericidal concentration (MBC) of OR Scrub against Pseudomonas aeruginosa and several strains of S. marcescens was less than or equal to 1:2. By comparison, a non-antiseptic soap from the same manufacturer (Wash) and 4% chlorhexidine (Hibiclens) had MBCs for all strains tested of at least 1:64. Time-kill curves confirmed the findings of the initial experiments. This is the first report of extrinsic contamination of antiseptic soap containing triclosan. No infections could be attributed to the contaminated soap, but sporadic outbreaks of Serratia have occurred in the intensive care unit with no identifiable source. Although there have been few studies on the impact of antiseptic soap in reducing nosocomial infection, we question whether a soap with the limitations of OR Scrub should be used in intensive care units or operating rooms.

Candida↗
PubMed1984

Serotypes of Streptococcus pneumoniae isolated from blood cultures at Boston City Hospital between 1979 and 1982.

Serotypes of pneumococci causing bacteremia were examined from January 1979 through December 1982. Of the 271 isolates recorded, 52% were from adults and 48% were from children. The rate of pneumococcal bacteremia for adults was 2.67 cases per 1,000 admissions; rates were not calculated for pediatric patients. The six most common pediatric types or groups (14, 19, 18, 6, 4, and 9) accounted for 90% of the total pediatric isolates, and the six most common adult types or groups (12, 9, 8, 4, 3, and 6) made up 55.3% of the total adult isolates. More than 96% of the pneumococcal types isolated from the blood cultures of pediatric patients are present in the 14-valent pneumococcal vaccine, compared with 72.7% of the adult isolates. The results demonstrate that most cases of pneumococcal bacteremia are caused by capsular types or groups present in the current vaccine and that minor changes in the types of pneumococci causing bacteremia have occurred during the past decade.

Adult↗
PubMed1984

A multivariate analysis of risk factors for hepatitis B virus infection among hospital employees screened for vaccination.

Previous studies of risk factors for hepatitis B virus infection among hospital employees have been based on surveys in single institutions or have been analyzed with univariate techniques. From November 1980 through August 1981, the authors performed a multi-institutional seroepidemiologic survey of hospital employees screened for entrance into a hepatitis B vaccine trial who represented groups at high risk for hepatitis B infection. Using a logistic regression model for the analysis of risk factors, the investigators determined the relative odds and 95% confidence intervals for risk of hepatitis B infection to be as follows: race (nonwhite/white: 3.4; 2.4-4.8) (p less than 0.001); history of acute viral hepatitis of an unspecified type (3.6; 2.2-5.9) (p less than 0.001); and employment at hospitals 1 through 5 as compared with hospital 6 (1.8; 1.1-2.9) (p = 0.015). In addition, certain job categories and the duration of employment within some of these categories were associated with increasing risk for hepatitis B infection over time. Laboratory workers (1.4; 1.2-1.7), surgical staff (1.2; 1.1-1.4), and medical staff (1.3; 1.1-1.5) had significant (p less than 0.05) increased risk of prior infection with longer duration of employment. Such time-job interaction was not demonstrable for nursing staff, anesthesiology staff, dental personnel, pathology staff, or ancillary personnel. The logistic regression model also shows that the highest gradient of risk for laboratory workers, surgeons, and medical staff occurs during the first five years of employment. An effective preventive strategy, such as the use of hepatitis B vaccine, should be targeted for these groups at the time of initial employment.

Adult↗
PubMed1984

Hepatitis B vaccine in health care personnel: safety, immunogenicity, and indicators of efficacy.

In a double-blind trial, we randomly assigned 1330 high-risk health care personnel to receive three 20-micrograms doses of hepatitis B vaccine or placebo. Among vaccine recipients 58% responded within 1 month and 97% within 9 months; there was no difference in immune response to the vaccine between men and women. Efficacy was evaluated after a mean follow-up of only 13.2 months, just before the vaccine was released commercially. Five hepatitis B infections were identified in placebo recipients and one in a vaccine recipient. Although the number of infections was too small to allow confident conclusions about protective efficacy of the vaccine, we saw a 67% reduction in the need for hepatitis B immune globulin after accidental hepatitis B inoculation in the vaccine group (relative risk, 5.08; 95% confidence intervals, 1.3 to 19.9). Minor side effects occurred with equal frequency after vaccine (28.7%) and placebo (27.2%) injections; no participant had a severe adverse reaction. Vaccination with the 20-micrograms hepatitis B vaccine was highly immunogenic and safe in health care workers.

Adult↗
PubMed1984

Contaminated condensate in mechanical ventilator circuits. A risk factor for nosocomial pneumonia?

We studied ventilator circuit colonization and condensate formation in 30 mechanical ventilators during the first 24 h after a circuit change. Parts of the circuit nearest the patient were more frequently contaminated and had the highest levels of colonization. There was rapid colonization of tubing after a circuit change; 33% of the ventilators were colonized at 2 h, 64% at 12 h, and 80% at 24 h. The median level of colonization at 24 h was 7 X 10(4) organisms/ml. Water condensate collected in the ventilator circuits at a mean rate of 30 ml/h (range, 10 to 60 ml/h). At 24 h, 80% of the condensate samples were contaminated at a median level of 2 X 10(5) organisms/ml. The bacteria isolated from the condensate usually correlated with organisms previously isolated from the patient's sputum, suggesting that the patient's oropharyngeal flora is the primary source of circuit colonization. Highly contaminated condensate in the ventilator circuit may be a significant risk factor for nosocomial pneumonia. We suggest that circuit condensate be emptied regularly, handled as infectious waste, and that special efforts be taken to prevent contaminated condensate from inadvertently washing into the patient's tracheobronchial tree.

Bacterial Infections↗
PubMed1983

Hepatitis B exposure in emergency medical personnel. Prevalence of serologic markers and need for immunization.

To assess the occupational risk of hepatitis B infection in emergency medical personnel, a seroepidemiologic survey of 87 emergency medical technicians and paramedics was conducted. Serologic markers indicating exposure to hepatitis B virus were detected in 18 percent. The prevalence of markers was associated with race (p = 0.006), with a relative risk of 3.5 (95 percent confidence interval 1.42 to 8.63) for nonwhites. Seropositivity was not associated with age, sex, previous clinical hepatitis, or blood transfusion. There was a suggestion that duration of employment as an emergency medical technician was related to the prevalence of hepatitis B markers (p = 0.11). Efforts to control the risk of hepatitis B infection in this profession are complicated by unique problems with post-exposure prophylaxis and uncontrolled exposure to blood. Immunization with hepatitis B vaccine would be the optimal strategy to reduce infection in this high-risk occupation.

Adult↗
PubMed1983

Vancomycin treatment of bacteremia caused by oxacillin-resistant Staphylococcus aureus: comparison with beta-lactam antibiotic treatment of bacteremia caused by oxacillin-sensitive Staphylococcus aureus.

The epidemiology and therapy of 29 episodes of bacteremia caused by oxacillin- and aminoglycoside-resistant Staphylococcus aureus (OARSA) were compared with 29 episodes of bacteremia due to oxacillin-sensitive S. aureus (OSSA) that occurred during a 36-month period. Patients with bacteremia due to OSSA were younger (P less than 0.05) and were admitted more frequently with acute traumatic injury (P less than 0.01). The overall survival rate one month after persistent bacteremia was 74% for patients with OARSA bacteremia treated with vancomycin compared with 70% for patients with OSSA bacteremia treated with a beta-lactam antibiotic. The results indicate that vancomycin is an effective antibiotic for the treatment of bacteremia caused by OARSA and suggest that its effectiveness is comparable to that of beta-lactam antibiotic treatment of bacteremia due to OSSA.

Anti-Bacterial Agents↗
PubMed1982

Contamination of mechanical ventilators with tubing changes every 24 or 48 hours.

We studied the contamination of ventilator circuits in order to assess the need for daily changes of tubing. Patients requiring continuous mechanical ventilation were randomly selected for tubing changes at 24 hours (Group 1) or at 48 hours (Group 2). Samples of inspiratory-phase gas from ventilators with standardized settings were cultured according to the tube-broth method of Edmondson and Sanford. The frequency of positive cultures from 128 ventilators in Group 1 (30 per cent) was not significantly different from that for 112 ventilators in Group 2 (32 per cent). Gram-negative bacteria were most frequently isolated from patient's sputum and ventilator inspiratory-phase gas, but no species predominated in either group of patients. Further studies performed with the Aerotest and Andersen air samplers confirmed that the levels of inspiratory-phase-gas contamination were low in both groups. In addition, quantitative analysis of colonization of the tubing demonstrated no significant increase in colonization between 24 and 48 hours. The absence of a significant difference in inspiratory-phase-gas contamination or tubing colonization suggests that ventilator tubing need be changed only every 48 hours.

Bacteria↗
PubMed1982

Natural bactericidal activity of human serum against Neisseria meningitidis isolates of different serogroups and serotypes.

We used a microtiter assay, standardized with serum-sensitive and serum-resistant strains of Neisseria gonorrhoeae, to determine the serum sensitivity of Neisseria meningitidis isolates of different serogroups and serotypes. Numbers of serum-resistant isolates varied among serogroups: group A = 7/8 (88%), group B = 26/50 (52%), group C = 5/8 (63%), group Y = 4/6 (67%), group W135 = 5/8 (63%), group 29E (Z') = 0/8 (0%), nongroupable isolates = 0/8 (0%). In comparison to group B isolates, group A isolates were more serum resistant (P less than 0.06), and group 29E and nongroupable isolates were more serum sensitive (P less than 0.001). Poor correlation was observed between serum sensitivity results and group-specific levels of bactericidal antibody in the normal human serum of volunteers. The frequency of serum-resistant strains among group B disease isolates (45%) was not significantly different from throat isolates of asymptomatic carriers (52%). Serotype 2 isolates of group B were no more serum resistant than were other serotypes examined. The serum sensitivity of meningococci appears to involve both capsular and noncapsular antigens and varies between serogroups. The increased serum sensitivity of nongroupable and group 29E isolates may account for the low incidence of disease caused by these organisms.

Antibodies, Bacterial↗
PubMed1981

A large outbreak of infections caused by a strain of Staphylococcus aureus resistant of oxacillin and aminoglycosides.

An extensive outbreak of nosocomial infections caused by oxacillin- and aminoglycoside-resistant Staphylococcus aureus (OARSA) occurred over a 16 month period. A total of 349 isolates of OARSA were obtained from 174 patients. Colonization with OARSA was found in 92 patients. There was 120 infections in 82 patients; 50 were surgical wound infections, 13 were nonsurgical wound infections, six were pneumonias, 15 were urinary tract infections, 12 were intravenous site infections, and there were 19 episodes of bacteremia (seven transient, 12 persistent). In patients with persistent bacteremia, the mortality rate was 33 percent. In patients treated for persistent bacteremia with vancomycin, the survival rate was 80 percent. Infections were highly associated with the surgical intensive care unit, and 90 percent of the isolates of OARSA tested had the same phage-type. Elderly patients with significant underlying disease, a history of previous surgery or of prior antimicrobial therapy appeared to be at increased risk for OARSA infections. OARSA were resistant to multiple antibiotics besides oxacillin, but all isolates were sensitive to vancomycin and rifampin. Three surgical intensive care unit nurses were found to be nasal carriers of OARSA, and one nurse had dermatitis of both hands colonized with OARSA. Following the removal of these nurses from the surgical intensive care unit and the institution of strict infection control measures, the number of OARSA infections and colonizations decreased to less than one per month. OARSA produces serious nosocomial disease, and epidemiologic intervention was effective in controlling this outbreak.

Adult↗
PubMed1981

Metabolic analysis of serologically defined Neisseria meningitidis isolates by frequency-pulsed electron capture gas-liquid chromatography.

Eight serogroups [A, B, C, D, X, Y, 29E [Z'], and W135] along with nongroupable and nontypable strains of Neisseria meningitidis were cultured in a defined liquid medium. The whole-culture spent medium was extracted, derivatized, and analyzed by frequency-pulsed electron capture gas-liquid chromatography. The frequency-pulsed electron capture gas-liquid chromatography profiles were then used to group the organisms on the basis of their metabolic profiles. First, two basic groups were formed which consisted of elevated spent-medium compounds and reduced spent-medium compounds. Then, these two basic groups were further subdivided on the basis of metabolites and cellular fatty acids detected in the spent medium to form a total of seven metabolic groups. The nongroupable strains (with the exception of two strains) fell within one of these metabolic groups. The elevated spent-medium compounds group contained all of the A, B, Y, and Z' strains, and the reduced spent-medium compounds group contained most of the C and all of the W135 and D strains. The potential usefulness of the metabolic group scheme is discussed.

Chromatography, Gas↗
PubMed1980

Gram-negative bacteremia. III. Reassessment of etiology, epidemiology and ecology in 612 patients.

Evaluation of 612 episodes of gram-negative bacteremia over a 10-year period demonstrated its progressively increasing frequency. This increase was associated with an increasing proportion of patients with more severe underlying disease, increasing patient age, increasing frequency of cardiac surgery and manipulative procedures, and increasing frequency of treatment with antibiotics, corticosteroids and antimetabolites in patients with bacteremia. Fatality rates paralleled the severity of the host's underlying disease as noted in previous reports. The urinary tract was the most frequent source of bacteremia, but in 30 per cent of the patients, predominantly those with more severe underlying disease, the original source could not be identified. Of all blood cultures obtained in these patients, 72 per cent were positive. Bacteremia was of low magnitude with 77 per cent of the patients have quantitative blood cultures with less than 10 gram-negative bacilli per milliliter of blood. Escherichia coli was the most frequent etiologic agent followed in frequency by Klebsiella-Enterobacter-Serratia species, Pseudomonas aeruginosa, Proteus and Providencia species, and species of Bacteroides. Sixteen per cent of the bacteremias were polymicrobic. K and O-antigen typing of Escherichia coli and capsular typing of K. pneumoniae demonstrated that a large number of serologic types of these strains were responsible for bacteremia. Over-all, bacteremia caused by multiple species of bacteria was associated with higher fatality rates, but no significant differences in fatality rates could be demonstrated for bacteremias caused by individual species of gram-negative bacilli when comparisons were made between patients with underlying diseases of similar severity. The presence or type of K-antigen did not influence the lethality of Esch. coli infections. Although some O-antigen types, 0:4, 0:6 and 0:8, were associated with higher fatality rates than other O-antigen types, "rough" or autoagglutinable Esch. coli were as lethal as smooth strains. These findings indicate that bacterial factors, other than antibiotic resistance, have little influence on the outcome of gram-negative bacteremia and that gram-negative bacilli function primarily as "opportunistic" pathogens.

Adolescent↗
PubMed1980

Gram-negative bacteremia. IV. Re-evaluation of clinical features and treatment in 612 patients.

Clinical features and specific aspects of treatment were evaluated in 612 patients with gram-negative bacteremia observed over a 10 year period. Coagulation abnormalities or thrombocytopenia were observed in 64 per cent of the patients. Evidence of disseminated intravascular coagulation (DIC) was found in approximately 10 per cent of them but was of sufficient severity to be associated with subcutaneous or visceral bleeding in 3 per cent of them. The frequency of coagulation abnormalities, other than DIC, was greater in patients with more severe underlying disease but DIC occurred with similar frequency irrespective of the severity of underyling host disease. Coagulation abnormalities of all types were associated with increased fatality rates. Hypothermia was noted in 13 per cent of the patients at the onset of bacteremia but was transient and was not associated with increased fatality. Failure to mount a febrile response greater than 99.6 degrees F within the first 24 hours of bacteremia was associated with a significant increase in fatality rates. Prior corticosteroid therapy diminished the febrile response to bacteremia. Age, underlying host disease, granulocytopenia, congestive heart failure, diabetes mellitus, renal insufficiency, nosocomial infections, and antecedent treatment with antibiotics, corticosteroids, and antimetabolites significantly increased fatality rates. Appropriate antibiotic treatment reduced the fatality rate of those with bacteremia by approximately one-half among patients in each category of severity of underlying host disease. In addition, it was shown that early appropriate antibiotic therapy also reduced the frequency with which shock developed by one half. Even after development of shock, appropriate antibiotic therapy significantly reduced fatality rates. The use of combinations of antibiotics could not be demonstrated to significantly improve survival rates. Minimal differences in therapeutic efficacy could be demonstrated between individual antibiotics and various combinations of antimicrobials. Shock occurred in approximately 40 per cent of the patients and its frequency was not influenced by the species of etiologic agent. Contrary to previous reports, corticosteroid therapy in patients with shock did not enhance survival and treatment with an average of 4.0 g/day of hydrocortisone or its equivalents was associated with a significant increase in fatality rates.

Adolescent↗