TST reversion in a BCG-revaccinated population of nursing and medical students, São Paulo, Brazil, 1997-2000.

SETTING: A major university in São Paulo, Brazil, where vaccination against tuberculosis (TB) with bacille Calmette-Guerin (BCG) was routinely offered to first-year medical and nursing students. OBJECTIVES: To estimate the probability of negative tuberculin skin test (TST) results over a 4-year period following BCG revaccination, and to evaluate the effect of factors associated with reversion. DESIGN: Students were enrolled in 1997, initially given a two-step TST, and were retested annually or biannually for the duration of the study. Data on TB exposures and potential risk factors for TST negativity and reversion were collected through annual surveys. A linear mixture survival model was used to estimate the probability of negative TST results over time. RESULTS: Of 159 students, an estimated 20% had a negative TST result despite revaccination, and a further 31% reverted to negative over 4 years of follow-up. No cofactors significantly affected the probability of reversion. CONCLUSION: Overall, in the absence of reported exposure to Mycobacterium tuberculosis, 51% of students revaccinated upon entering nursing or medical school would have a negative TST result by the time they begin their internships. In this recently vaccinated population, reversion was common, suggesting that annual TST screening may remain a useful tool.

A multicenter evaluation of tuberculin skin test positivity and conversion among health care workers in Brazilian hospitals.

SETTING: Four general Brazilian hospitals. OBJECTIVE: To assess the occupational risk of Mycobacterium tuberculosis (TB) in participating hospitals. DESIGN: In phase one of this longitudinal study, a cross-sectional survey documented baseline tuberculin skin test (TST) positivity rates. In phase two, TST conversion rates were evaluated in participants with an initial negative two-step TST. TST conversion data were analyzed to determine risk factors for TB infection using an increase of > or = 10 mm compared to baseline TST. RESULTS: The initial TST positivity rate was 63.1%; the follow-up TST conversion rate was 10.7 per 1000 person-months (p-m). Hospital of employment, recent bacille Calmette-Guerin (BCG) vaccination, nosocomial TB exposure, and employment as a nurse were independent risk factors for TST conversion. Hospitals without TB infection control measures had higher conversion rates than those with control measures (16.0 vs. 7.8/ 1000 p-m, P < 0.001). CONCLUSIONS: This study indicates an important occupational risk of infection in health care settings with a high TB incidence. Longitudinal TST studies are a valuable tool to assess the occupational risk of TB, even in BCG-vaccinated populations, and should be used to direct limited resources for infection control.

Prevalence of nosocomial infections in neonatal intensive care unit patients: Results from the first national point-prevalence survey.

OBJECTIVES: Patients admitted to neonatal intensive care units (NICUs) are at high risk of nosocomial infection. We conducted a national multicenter assessment of nosocomial infections in NICUs to determine the prevalence of infections, describe associated risk factors, and help focus prevention efforts. STUDY DESIGN: We conducted a point prevalence survey of nosocomial infections in 29 Pediatric Prevention Network NICUs. Patients present on the survey date were included. Data were collected on underlying diagnoses, therapeutic interventions/treatments, infections, and outcomes. RESULTS: Of the 827 patients surveyed, 94 (11.4%) had 116 NICU-acquired infections: bloodstream (52.6%), lower respiratory tract (12.9%), ear-nose-throat (8.6%), or urinary tract infections (8.6%). Infants with infections were of significantly lower birth weight (median 1006 g [range 441 to 4460 g] vs 1589 g [range 326 to 5480 g]; P <.001) and had longer median durations of stay than those without infections (88 days [range 8 to 279 days] vs 32 days [range 1 to 483 days]; P <.001). Most common pathogens were coagulase-negative staphylococci and enterococci. Patients with central intravascular catheters (relative risk = 3.81, CI 2.32-6.25; P <.001) or receiving total parenteral nutrition (relative risk = 5.72, CI 3.45-9.49; P <.001) were at greater risk of bloodstream infection. CONCLUSIONS: This study documents the high prevalence of nosocomial infections in patients in NICUs and the urgent need for more effective prevention interventions.

Status of infection surveillance and control programs in the United States, 1992-1996. Association for Professionals in Infection Control and Epidemiology, Inc.

BACKGROUND: Nosocomial infections have been recognized as a source of morbidity and mortality throughout the world for several decades. In the United States, an estimated 2.1 million nosocomial infections occur annually in acute care hospitals alone. Infection surveillance and control programs (ISCPs) play a vital role in addressing this problem, but no national studies have described the status and composition of these programs since the 1970s. METHODS: In January 1997, a voluntary survey was sent by mail to members of the Association for Professionals in Infection Control and Epidemiology, Inc. Only one response per facility was requested. The survey asked for information for the years 1992 to 1996 (study period), and questions pertained to characteristics of the health care facility in which the respondent worked, characteristics of the ISCP and its personnel, and the overall level of administration support for infection control activities. RESULTS: Completed questionnaires were received from personnel at 187 health care facilities located in 40 states and the District of Columbia. The majority (76.5%) of responding facilities were nongovernment owned, and 57.2% were classified as general acute care facilities. The number of licensed beds at these facilities remained stable throughout the study period, but all other measures of facility size and activity (eg, number of patient days and number of nurses) decreased by as much as 28.9%. In 1992, ISCPs were most likely to be organizationally located in the Nursing Department, but by 1996, many had been transferred to departments of Medical Records, Quality Assurance, or Risk Management. Throughout the course of the study period, the number of facilities performing surveillance for health care-associated infections in outpatient settings increased by 44.0%, from 100 to 144. In 1996, only 47.6% of facilities had a hospital epidemiologist (HE), and HEs devoted a median of 15% or less of their time to infection control activities. For the most part, HEs were trained in infectious diseases, and few had certification in infection control. Infection control professionals (ICPs) were much more common than were HEs (ICPs were reported at 97.9% of respondents' facilities in 1996), and they spent the majority (80% in 1996) of their time on infection control activities. During the course of the study period, increasing numbers of facilities had ICPs who had certification in infection control. Furthermore, most respondents did not report a change over time in the level of administration support for infection control activities. CONCLUSIONS: Health care delivery has changed dramatically during the past 20 years. This study presents an updated description of ISCPs in the United States. Our results illustrate several changing parameters, such as departmental shifts and increased outpatient surveillance, that reflect adjustments in health care priorities during the study period. As the transformation of the health care system continues, continued evaluation of the status of ISCPs on a national level will be necessary. Diligent monitoring, proactive measures, and collaboration between infection control organizations and government agencies will be vital for the prevention and control of health care-associated infections in the future.

Susceptibility of Panamanian Aotus lemurinus lemurinus to sporozoite-induced Plasmodium falciparum (Santa Lucia) infection.

Aotus monkeys are good models for erythrocyte-induced Plasmodium falciparum and P. vivax infections and have been extensively used in malarial drug and vaccine development. Recently, it has been shown that certain species of Aotus can be infected with sporozoites, and that the degree of susceptibility varies among species. We demonstrate here that Panamanian Aotus lemurinus lemurinus are susceptible to a sporozoite-induced infection, opening the possibility that this species of Aotus could be used as models for testing the efficacy of pre-erythrocytic P. falciparum vaccines and drug candidates directed at the pre-erythrocytic stages of P. falciparum and P. vivax malaria. In this species, we compared sporozoite infection rates. Two of four animals splenectomized prior to infection with sporozoites developed patent parasitemias. Seven of eight animals splenectomized either 7 or 35 days after infection became parasitemic. Additionally, we used a P. falciparum-specific polymerase chain reaction (PCR) method to detect the early appearance of parasitized erythrocytes in the blood prior to detection by conventional microscopy, and found that the parasitemia was detected first in five animals by the PCR method, first in three animals by blood film, with one parasitemia detected simultaneously. We also demonstrated the feasibility of infecting monkeys located in Panama with sporozoites isolated at an insectary in Atlanta, thus documenting the feasibility of similar studies where the insectary and monkey colony are not in the same location. A subsequent attempt to infect these monkeys using sporozoites was not successful, suggesting that this model of human malaria is not yet ready for routine use in vaccine or drug efficacy screening. This model merits further study because of the importance of testing pre-erythrocytic P. falciparum malaria vaccines and drugs in animals.

The emergence of decreased susceptibility to vancomycin in Staphylococcus epidermidis.

BACKGROUND: Coagulase-negative staphylococci (CNS) are the major cause of nosocomial bloodstream infection. Emergence of vancomycin resistance among CNS is a serious public health concern, because CNS usually are multidrug-resistant, and glycopeptide antibiotics, among which only vancomycin is available in the United States, are the only remaining effective therapy. In this report, we describe the first bloodstream infection in the United States associated with a Staphylococcus epidermidis strain with decreased susceptibility to vancomycin. METHODS: We reviewed the hospital's microbiology records for all CNS strains, reviewed the patient's medical and laboratory records, and obtained all available CNS isolates with decreased susceptibility to vancomycin. Blood cultures were processed and CNS isolates identified by using standard methods; antimicrobial susceptibility was determined by using minimum inhibitory concentration (MIC) and disk-diffusion methods. Nares cultures were obtained from exposed healthcare workers (HCWs) to identify possible colonization by CNS with decreased susceptibility to vancomycin. RESULTS: The bloodstream infection by an S. epidermidis strain with decreased susceptibility to vancomycin occurred in a 49-year-old woman with carcinoma. She had two blood cultures positive for CNS; both isolates were S. epidermidis. Although susceptible to vancomycin by the disk-diffusion method (16-17 mm), the isolates were intermediate by MIC (8-6 microg/mL). The patient had received an extended course of vancomycin therapy; she died of her underlying disease. No HCW was colonized by CNS with decreased susceptibility to vancomycin. CONCLUSIONS: This is the first report in the United States of bloodstream infection due to S. epidermidis with decreased susceptibility to vancomycin. Contact precautions likely played a role in preventing nosocomial transmission of this strain, and disk-diffusion methods may be inadequate to detect CNS with decreased susceptibility to vancomycin.

Invasive Aspergillus spp infections in rheumatology patients.

OBJECTIVE: The number of immunocompromised patients in hospitals has increased, resulting in a concomitant increase in the number of Aspergillus spp infections, with an exceedingly high death rate. From January 1995 through June 1996, 7 patients acquired invasive aspergillosis at a Maryland hospital (Hospital A). No cases had been detected in 1994. METHODS: To determine risk factors for infection, we conducted a case-control study and an environmental evaluation. A case was defined as histopathologic evidence of invasive Aspergillus spp infection in any Hospital A patient admitted from January 1994 through July 1996. RESULTS: Of 7 case patients identified, 5 were rheumatology patients hospitalized on 2 wards. Rheumatology case patients were more likely than randomly selected rheumatology patients without invasive Aspergillus spp infection (controls) to die (p = 0.004), to have longer hospitalization both in current (p = 0.008) and prior (p = 0.001) admissions, to receive high doses of intravenous immunosuppressive agents (p = 0.03), or to receive immunosuppressive agents for a longer period of time (p = 0.001). The environmental evaluation showed that construction areas were neither sealed off from patient care areas nor under negative pressure relative to patient-care areas. The air flow from patients' rooms was not positive in relation to the hallway and had only 1.6 air changes per hour. CONCLUSION: This investigation suggests that rheumatology patients, particularly those receiving high dose intravenous immunosuppressive agents, are at increased risk of invasive Aspergillus spp infection. A high index of suspicion for the diagnosis of nosocomial aspergillosis should be maintained in these patients and, when hospitalized, they should be assigned to rooms removed from or physically separated from construction activity.