To investigate a cluster of seven pneumonia cases among persons exposed to a pet-shop worker hospitalized with psittacosis.

Epidemiological study of the outbreak, sero-diagnostic evaluation of exposed persons with pneumonia; and retrospective review of the pneumonia cases.

450-bed teaching community hospital.

Employees of the nursing unit where the patient with psittacosis was hospitalized.

The index case had laboratory and clinical evidence of psittacosis. Four of the seven exposed persons who developed pneumonia had serologic results that met criteria for a diagnosis of psittacosis, and three met criteria for Chlamydia pneumoniae infection, possibly reflecting cross-reactivity between the microimmunofluo-rescence assays for the two diseases. The epidemiological graph suggested a relationship between the index case and the cluster of pneumonias in exposed individuals.

Psittacosis may have been transmitted person to person in a hospital setting.

To identify risk factors predictive of nosocomial infection in an intensive-care unit (ICU) and to identify patients with a higher risk of nosocomial infection using a predictive model of nosocomial infection in our ICU.

Prospective study; daily concurrent surveillance of intensive-care-unit patients.

All patients admitted for at least 24 hours to the ICU of a tertiary-level hospital from February to November 1994 were followed daily.

Variables measuring extrinsic and intrinsic risk factors for nosocomial infection were collected on each patient during their ICU stay, and the Cox Proportional Hazards multivariable technique was used to identify the variables significantly associated with infection.

The population studied consisted of 944 patients. The main risk factors identified were intrinsic; the significant extrinsic risk ofactors identified were head of the bed in a horizontal (<30°) position (this variable presented the highest increase of the infection hazard ratio) and the use of sedative medication. Patients presenting the highest risk scores using the predictive model are those with the highest risk of nosocomial infection.

The important preventive measures derived from our results are that underlying conditions suffered by the patient at the ICU admission should be corrected promptly, the depression of the patient's level of consciousness with sedatives should be monitored carefully, and the horizontal position of the head of the bed should be avoided totally. Patients with a high risk of infection can be the target of special preventive measures.

To determine if varicella vaccination of healthcare workers would result in a net cost savings.

A Markov-based decision analysis.

The analysis was based on a hypothetical population of healthcare workers. Data were obtained from exposure records of a tertiary-care hospital and from the literature. Workers were considered potentially susceptible if they had no past history of varicella.

Vaccination of potentially susceptible workers would result in a net cost savings of $59 per person. Serological testing prior to vaccination resulted in smaller net savings. The results were robust across a wide range of assumptions. Importantly, however, the result was very dependent on infection control policy regarding work restrictions for vaccine recipients. If more than 3% of vaccinees were removed from work due to vaccine-associated rash, vaccination no longer would result in a net cost savings.

Varicella vaccination of potentially susceptible healthcare workers can reduce costs and decrease morbidity. Infection control policy regarding work restrictions for vaccine recipients will play a key role in the feasibility of vaccination.

To determine if compliance with annual tuberculosis skin testing correlated with the number of cases of tuberculosis seen in patients and healthcare workers.

Survey using a written questionnaire.

159 Veterans' Administration facilities.

Hospitals that reported that >80% of their healthcare workers received annual skin tests saw 12.7 patient cases per 10,000 admissions and 4.0 healthcare worker cases per 10,000 personnel. Facilities in which <20% of their healthcare workers were given annual skin tests saw 4.5 cases per 10,000 admissions and 1.6 cases in healthcare workers per 10,000 personnel (P<.001 for patients and P=.31 for healthcare workers). The ratio of the median number of patients placed in acid-fast bacilli (AFB) isolation to the median number of patients with confirmed tuberculosis was 12. There was no correlation of this ratio with the number of cases of tuberculosis in patients or healthcare workers seen in each facility.

Compliance with annual tuberculosis skin testing was related directly to the rate of tuberculosis seen in patients. More standardized policies for placing patients in AFB isolation are needed to control for potentially costly variation among facilities. These measures should have highest priority in the control of tuberculosis in the healthcare setting, before implementing still more expensive interventions.

To quantify specific factors believed to increase healthcare worker (HCW) risk for contaminated sharps injuries (eg, visibility, communication, and range of motion); to quantify the degree to which respirators of various designs impacted those same factors; and to assess HCW opinions about the suitability of selected respirators with respect to patient care and user compliance criteria.

Sharps injury data from seven hospitals were analyzed to determine the potential contribution of visibility, communication, and range of motion to reported injuries. Healthcare workers representing various clinical specialties and physical characteristics were examined at baseline and while wearing five different respirators to quantify the impact of respirator design on visibility, communication, and range of motion. Healthcare workers were inter viewed and completed a survey assessing each respirator.

Hospital and ambulatory-care settings.

Population-based and convenience sample.

Communication, visibility, and range of motion were found to affect contaminated sharps injuries significantly. Selected high-efficiency particulate air (HEPA) respirators were found to have a negative impact on each of these variables. Healthcare workers involved in the study also reported compliance criteria problems with selected HEPA respirators, which may effect implementation of respiratory precautions adversely.

Current HEPA respirators, because of their design, potentially increase the risk of bloodborne pathogen exposure through sharps injuries. We conclude that mandating respirators without regard to the potential impact of their design to the sharps injuries may be counterproductive to HCW safety, because they may increase, rather than decrease, overall occupational risk to HCWs.

Investigate the nosocomial transmission of Trichophyton tonsurans tinea corporis.

Descriptive study of a nosocomial epidemic of tinea corporis.

A free-standing inpatient rehabilitation facility.

Patients and healthcare workers present on an inpatient rehabilitation ward at the time of transmission of tinea corporis.

T tonsurans tinea corporis was transmitted from one patient to four healthcare workers despite early diagnosis and treatment. Infection rates for healthcare workers having major, moderate, and minor contact with the index case were 30%, 17%, and 0%, respectively (overall rate, 25%).

This study identifies rehabilitation inpatients as another population in which nosocomial transmission of T tonsurans tinea corporis can occur. The high attack rate and transmission, despite early diagnosis and treatment, emphasizes the need for isolation precautions.

Recently, blunt 18-gauge (ga) metal cannulae have become nationally commercially available as safety products. The ability of these blunt cannulae to prevent needlestick injury and to enable direct access of all standard latex ports and vial membranes, thus eliminating hypodermic needles entirely from the intravenous (IV) drug administration process, is assessed.

In the laboratory setting, the needlestick injury potential of small-bore blunt cannulae versus hypodermic needles was studied using blinded and randomized methods. Insertion force requirements were studied for cannulae and needles. Metal 18-ga blunt cannulae were inserted into four brands of standard Y-ports and vial stoppers to assess postpuncture integrity and force requirements.

Needlestick injury did not occur using small-bore blunt cannulae (P<.001; n=51). Metal 18-ga cannulae passed into prepierced standard Y-ports as easily as hypodermic needles and without loss of Y-port integrity. Insertion of metal 18-ga cannulae without prior port puncture was possible, but was associated with substantial coring and loss of integrity of the port seal, except for IVAC brand ports (P<.03).

Metal 18-ga cannulae can be inserted through virtually all intact standard rubber vial membranes or standard Y-ports to allow safe IV access. A single prepuncture of any standard latex membrane allows economical blunt metal cannula access equally efficiently as with expensive pre-slit membranes and without loss of membrane integrity.

To evaluate whether hospital strains of antibiotic-resistant bacteria exhibited altered susceptibility to disinfectants.

Antibiotic-susceptible bacteria were obtained from American Type Culture Collection: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Salmonella choleraesuis, and Pseudomonas aeruginosa. Hospital strains of antibiotic-resistant bacteria were obtained from clinical isolates, including: S aureus, S epidermidis, E coli, Enterococcus species, K pneumoniae, and P aeruginosa. The Association of Official Analytical Chemist's use-dilution method was used to test these 12 strains of 7 bacterial pathogens for their susceptibility to a phenol and a quaternary ammonium compound. For five pathogens, we tested a susceptible and a more resistant strain in 20 comparative trials (5 pathogens, 2 disinfectants, 2 dilutions per disinfectant).

In our 20 comparative trials, the antibiotic-resistant strains exhibited an increased resistance to the disinfectant in only a single instance.

Our data demonstrate that the development of antibiotic resistance does not appear to be correlated to increased resistance to disinfectants.

To study the cost-effectiveness of vaccination for hepatitis A.

Hypothetical analysis of students currently enrolled in medical school in the United States.

A Markov-based model was developed using data from the literature, actual hospital costs, and an annual discount rate of 5%. The incidence rate was based on the lowest annual rate for the US population during the past decade.

Over the lifetimes of students currently in medical school, the model estimated that there would be 286 hepatitis A cases with four deaths and 107 lost years of life. With routine vaccination, these numbers would decrease to 17, 0.3, and 6, respectively. The costs per life-year saved and quality adjusted life-year saved were $58,000 and $47,000, respectively. Serologic screening prior to vaccination was less cost-effective than universal vaccination. If the incidence of hepatitis A was underestimated by a factor of 5, the cost per life-year saved would decrease to $5,500. If the incidence of hepatitis was underestimated by a factor of 10, vaccination would result in a net cost savings.

We conclude that the cost per life-year saved by routine hepatitis A vaccination was similar to many other standard medical modalities. For routine vaccination of medical students to be cost-saving, the incidence rate for hepatitis A must be at least 10 times higher than the rate presently reported for the general population. Serological screening prior to vaccination was not cost-effective.

To evaluate a possible commonsource outbreak of Candida infections in the neonatal intensive-care unit. Systemic Candida infections increased from 6 to 11 cases (0.71 to 1.34 per 1,000 patient-days). In addition, Candida parapsilosis infections increased from 1 in 1992 to 10 in 1993.

Tertiary-care, teaching, pediatric institution with a 40-bed neonatal intensive-care unit (NICU). Clinical characteristics, associated conditions, and antimicrobial therapy were obtained from the medical records of all NICU patients with positive blood cultures for Candida during 1992 and 1993. Nineteen Candida isolates from 15 infants were studied retrospectively using contour-clamped homogeneous electric-field (CHEF) electrophoresis.

CHEF revealed eight karyotypes of C parapsilosis. Five isolates recovered from four patients shared one karyotype. The remaining isolates from seven infants all had distinctly different karyotypes.

The evidence was insufficient to implicate a single source of infection, even though four patients in the same unit had identical strain types. However, identical strains of C parapsilosis were associated geographically, suggesting that nosocomial acquisition of C parapsilosis through indirect patient contact in the NICU was possible. The CHEF technique yields unique patterns that may be used to delineate clinical isolates and to study the molecular epidemiology of candidal infections.

To describe the investigation of a pseudo-outbreak of multiresistant Pseudomonas aeruginosa fecal colonization in a hematology unit.

Retrospective chart review; prospective environmental sampling and observation of stool culture technique; genotyping by random arbitrary primer polymorphic DNA polymerase chain reaction (RAPD-PCR).

An academic tertiary-care hospital.

Between August and October 1994, P aeruginosa resistant to imipenem, ceftazidime, ciprofloxacin, and all aminoglycosides was isolated from surveillance stool cultures from 10 neutropenic patients cared for in the hematology unit. P aeruginosa, with an identical susceptibility pattern, was isolated from three patients admitted to the same unit in the year before the “outbreak.” Two months before the outbreak, 12 healthcare workers had been added to the staff.

Observation of stool sampling techniques as performed by healthcare workers revealed that samples for surveillance cultures were taken from feces in the toilet. When the proper sampling technique was used, P aeruginosa was not isolated from stool samples from 8 of 10 patients with previously positive cultures. P aeruginosa also was isolated from two wash basins, toilet flushing water, and a toilet brush. Genotyping by RAPD-PCR showed that the isolate from the toilet flushing water was identical to the P aeruginosa strains of eight patients from the outbreak.

This pseudo-outbreak emphasizes the importance of proper sampling techniques and that periodic observation may be necessary to verify proper sampling techniques.

To determine the knowledge of rubella immune status among practicing obstetrician-gynecologists in the United States and of rubella immunity policies covering healthcare workers in the obstetric-care office setting.

Mailed survey questionnaire, August through December 1994.

Physicians from multiple-practice sites including private office, public institution, university or teaching hospital, and closed panel health maintenance organization settings.

3,302 practicing obstetrician-gynecologists, chosen by a systematic random sample from the AMA national physician database.

Participants were defined as rubella immune if they reported knowledge of prior rubella vaccination or positive antibody titer. Knowledge of a policy for documenting rubella immunity among employees in the office-based practice setting also was assessed.

Questionnaires were returned from 50% (1,666) of the 3,302 surveyed, and 96% (1,599) were evaluable. Approximately 20% (304/1,599) of the responding obstetrician-gynecologists did not have knowledge of documented rubella immunity, and the majority of office-based practices did not require documentation of rubella immunity in the following groups: physicians, 66% (723/1,094); office nurses, 62% (666/1,070); and other office staff, 69% (728/1,063). Sixty-two percent (993/1,599) of responding physicians had individual rubella serologies performed, with 916 known to be positive, 53 reported negative, and 24 reported unknown. Fifty-seven percent (918/1,599) reported receiving monovalent rubella vaccine or trivalent measles-mumps-rubella vaccine. Multiple logistic regression analysis revealed the following to be independent predictors of positive immune status among respondents: female gender (odds ratio [OR], 2.4; 95% confidence interval [CI95], 1.8-3.1), medical school graduation since 1980 (OR, 2.6; CI95, 2.0-3.3), providing obstetric or fertility services (OR, 1.5; CI95, 1.2-1.9), and group practice setting ≥5 physicians; OR, 1.2; CI95, 1.1-14).

Nationally, nearly one of every five practicing obstetricians may not have documented rubella immunity, and the majority of office-based practices have no system for assuring such immunity. Rubella immunity should extend beyond the hospital setting, with consideration for requiring rubella immunity as a condition for employment. Methods for effective implementation and documentation of current guidelines need to be addressed, particularly in the office setting.