To evaluate the efficacy of Centers for Disease Control and Prevention (CDC)-recommended infection control measures implemented in response to an outbreak of multidrug-resistant (MDR) tuberculosis (TB).

Retrospective cohort studies of acquired immunodeficiency syndrome (AIDS) patients and healthcare workers. The study period (January 1989 through September 1992) was divided into period I, before changes in infection control; period II, after aggressive use of administrative controls (eg, rapid placement of TB patients or suspected TB patients in single-patient rooms); and period III, while engineering changes were made (eg, improving ventilation in TB isolation rooms).

A New York City hospital that was the site of one of the first reported outbreaks of MDR-TB among AIDS patients in the United States.

All AIDS patients admitted during periods I and II. Healthcare workers on nine inpatient units with TB patients and six without TB patients.

The epidemic (38 patients) waned during period II and only one MDR-TB patient presented during period III. The MDR-TB attack rate among AIDS patients hospitalized on the same ward on the same days as an infectious MDR-TB patient was 8.8% (19 of 216) during period I, decreasing to 2.6% (5 of 193; P= 0.01) during period II. In a small group of healthcare workers with tuberculin skin test data, conversions during periods II through III were higher on wards with than without TB patients (5 of 29 versus 0 of 15; P= 0.15), although the difference was not statistically significant.

Transmission of MDR-TB among AIDS patients decreased markedly after enforcement of readily implementable administrative measures, ending the outbreak. However, tuberculin skin-test conversions among healthcare workers may not have been prevented by these measures. CDC guidelines for prevention of nosocomial transmission of TB should be implemented fully at all US hospitals.

To confirm the vertical transmission of Citrobacter diversus from a mother to her infant and to evaluate the epidemiologic usefulness of a new automated procedure for analysis of polymerase chain reaction (PCR)-generated DNA fingerprints.

Repetitive element-based PCR (rep-PCR) analysis of C diversus isolates from the blood and amniotic fluid of a mother and the blood of her infant was performed. Unrelated C diversus isolates also were characterized and compared with the isolates from mother and infant. DNA fingerprints were generated by gel electrophoresis of PCR products derived from either unlabeled standard repetitive sequence-based oligonucleotide primers or fluorescent primers. The standard rep-PCR fingerprints were analyzed by visual inspection. The fluorescent primers were used in fluorophore-enhanced rep-PCR (FERP), and the FERP DNA fingerprints were analyzed by an Applied BioSystems (ABI) Model 373A laser scanning unit equipped with Genescan 672 software (Applied Biosystems, Inc, Foster City, CA).

A mother and her newborn infant, both with invasive disease due to C diversus, in an urban tertiary-care hospital.

The DNA fingerprints of the maternal blood, amniotic fluid, and infant blood isolates of C diversus were identical by both visual inspection of ethidium bromide-stained agarose gels and computer-aided analysis of FERP patterns. These strains appeared to differ from all but one control isolate, which had been collected 7 years earlier in the same city in which the infant was born.

Vertical transmission of C diversus from mother to infant can occur in utero. Automated analysis of rep-PCR–generated DNA fingerprints derived using fluorescent primers is an objective means for comparing isolates of C diversus and in all likelihood would be useful for other species of bacteria that possess repetitive elements.

To investigate the cause of increasing rates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection at a university hospital.

Review of data collected by prospective hospitalwide surveillance regarding rates of nosocomial MRSA colonization and infection.

A 700-bed university hospital providing primary and tertiary care.

Patients admitted to the hospital between 1986 and 1993 who were found to be infected or colonized with MRSA.

Rates of MRSA infection and colonization.

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.

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.

We attempted to determine if an increase in resistance to ciprofloxacin occurred among nosocomial pathogens, especially Pseudomonas aeruginosa and Staphylococcus aureus.

We examined 1989-1992 ciprofloxacin susceptibility results from 8,517 P aeruginosa and 9,021 S aureus isolates associated with nosocomial infections reported to the National Nosocomial Infections Surveillance System.

For S aureus, 27.1% of isolates were resistant to ciprofloxacin; of methicillin-resistant S aureus isolates, 80% also were resistant to ciprofloxacin. A logistic regression model found that ciprofloxacin resistance was more common among S aureus isolated from the urinary and respiratory tracts than from other sites of isolation, and among isolates that were methicillin resistant. After controlling for these factors, the model showed a 123% increase in the odds of ciprofloxacin resistance from 1989-1990 to 1991-1992. For P aeruginosa, 4.7% of the isolates were resistant to ciprofloxacin. Resistance varied by site of infection and rose most dramatically for respiratory tract isolates from 2.0% in 1989-1990 to 5.3% in 1991-1992.

Resistance to ciprofloxacin is more frequent among nosocomial S aureus than among P aeruginosa and is increasing rapidly among S aureus isolates and from selected sites among P aeruginosa isolates.

To identify the tuberculosis (TB) skin-testing practices of long-term care facilities for the elderly in Toronto, Ontario.

A telephone survey using a 25-item questionnaire.

Twenty-nine nursing homes (NHs) and 26 Homes for the Aged (HFAs) in metropolitan Toronto.

Thirty-one percent of facilities (17 of 55) had no formal tuberculin skin-testing program, including 52% of NHs (15 of 29) versus 8% of HFAs (2 of 26; P= 0.001). Ninety-two percent of HFAs (24 of 26) compared with 45% of NHs (13 of 29), obtained preadmission or admission skin-test status of residents (P= 0.0005). Annual testing was performed at 46% of HFAs (12 of 26) and 27% of NHs (8 of 29; P= 0.28). Of facilities that carried out any skin testing, 64% of HFAs (16 of 25) versus 32% of NHs (6 of 19) measured induration to establish test positivity (P=0.068). Fifty-two percent of HFAs (13 of 25), compared with 21% of NHs (4 of 19), recorded the actual size of induration in the patient record (P=0.085). Only 28% of HFAs (7 of 25) and 21% of NHs (4 of 19) correctly defined a positive tuberculin skin test.

TB surveillance practices in long-term care institutions in Toronto are inadequate and often yield results that do not predict the risk of infection and cannot be used to investigate outbreaks. Tuberculin skin-testing practices were better at HFAs, which are subject to provincial legislation regarding TB surveillance, than at NHs, which are not subject to this legislation. Staff at HFAs and NHs require education regarding tuberculin skin-testing policies and procedures.

To investigate possible transmission of multidrug-resistant tuberculosis (MDR-TB) in a dental setting.

A retrospective, descriptive study of dental workers (DWs), patients, and practice characteristics.

Two dental workers (DW1 and DW2) with acquired immunodeficiency syndrome and MDR-TB.

A hospital-based (Hospital X) human immunodeficiency virus (HIV) dental clinic in New York City.

To identify dental patients with tuberculosis (TB), patients treated in the dental clinic at Hospital X during 1990 were cross-matched with those listed in the New York City Department of Health Tuberculosis Registry Mycobacterium tuberculosis isolates from both DWs and from dental patients with TB were tested for antimicrobial susceptibility and typed by restriction fragment length polymorphism (RFLP) analysis. Infection control practices were reviewed.

M tuberculosis isolates infecting DW1 and DW2 were resistant to isoniazid and rifampin and had identical RFLP patterns. DW1 and DW2 worked in close proximity to each other in a small HIV dental clinic in Hospital X during 1990. Of 472 patients treated in the dental clinic in 1990, 41 (8.7%) had culture-proven M tuberculosis infection. Of these 41, 5 had isolates with resistance patterns similar to both DWs; however, for four available isolates, the RFLP patterns were different from the patterns of the DWs. Sixteen of the 41 patients received dental treatment while potentially infectious. Dental patients were not routinely questioned about TB by dental staff, nor were all dental staff screened routinely for TB. No supplemental environmental measures for TB were employed in the dental clinic in 1990.

Our investigation suggests that MDR-TB transmission may have occurred between two DWs in an HIV dental clinic. Opportunities for transmission of TB among dental staff and patients were identified. TB surveillance programs for DWs and appropriate infection control strategies, including worker education, are needed to monitor and minimize exposure to TB in dental settings providing care to patients at risk for TB.

To compare the accuracy of infection control practitioners' (ICPs') classifications of operative site infection in Florida Consortium for Infection Control (FCIC) hospitals, in two time periods, 1990 to 1991 and 1991 to 1992, and to estimate the effect of duration of surveillance experience on that accuracy.

Medical record reviewers examined records of all patients classified by an ICP as infected, to distinguish false-positives from true infections based on evidence of standard infection criteria and the ICP's contemporaneous clinical observations. Reviewers also examined a random sample of 100 records from patients classified as noninfected for evidence of undetected infections (false-negatives). These observations permitted estimates of the sensitivity and specificity of each ICP's classification of infection status.

Fourteen FCIC communit:y hospitals at which performance of 16 ICPs was monitored.

There was a strong linear trend relating increasing sensitivity to numbers of years of ICP surveillance experience (P<.001). For ICPs with <4 years of experience, satisfactory sensitivity (≥80%) was reached in only one of 10 ICP-years of observation. For ICPs with ≥4 years' experience, satisfactory sensitivity was achieved for 14 of 18 person-years (P=.001). Estimated specificity was 97% to 100% for all ICP-years observed.

ICPs with <4 years of surveillance experience in FCIC community hospitals rarely achieved a satisfactory sensitivity estimate, whereas ICPs with≥4 years' experience generally did. Monitoring ICP surveillance accuracy through retrospective medical record audits offers an objective approach to evaluating ICP performance and to interpreting infection rates at different hospitals.

To validate a previously published model for predicting bacteremia in hospitalized patients.

Application of a published bacteremia prediction model to a prospective validation cohort of patients and comparison of its predictability to that found in the derivation cohort.

Urban, university-affiliated, 550-bed public hospital.

The validation cohort consisted of 342 patients with 559 blood culture episodes between October 14, 1992, and December 5, 1992. Each blood culture episode was scored based on the presence or absence of seven predictors of bacteremia and the findings compared with published results (derivation cohort).

None.

Application of the bacteremia prediction model to the validation cohort identified episodes with a low risk (3%) and a high risk (17%) for true bacteremia, similar to the findings in the derivation cohort (1% and 16%, respectively). Comparison of the predictions of the model in the two cohorts by receiver operator characteristic curve analysis revealed that the overall predictability of the model in the validation cohort was not as good as in the derivation cohort.

Although the bacteremia prediction model did not perform as well overall in the validation cohort, the model still was able to clearly define two extreme groups: those with a low risk and those with a high risk for true bacteremia. This predictive capability may aid physicians in prescribing empiric antimicrobial therapy and also may be useful to hospital epidemiologists in assessing quality of care