To describe a pneumonia outbreak caused by Streptococcus pneumoniae among residents of a home for the aged and to review contemporary pneumococcal outbreaks.

Epidemiological investigation.

S pneumoniae isolates were serotyped and analyzed by pulsed-field gel electrophoresis. Paired sera were tested for antibodies to pneumococcal surface adhesin A protein (PsaA, a 37-kDa cell-wall protein). Pneumococcal outbreaks reported in the last decade in English were reviewed.

Pneumonia developed in 18 of 200 residents. In 11 (61%), a pneumococcal etiology was demonstrated. S pneumoniae, serotype 4, was isolated from the blood cultures of 3 patients; all isolates were indistinguishable by pulsed-field gel electrophoresis. Pneumococcal involvement was established in 2 by sputum culture and latex agglutination of parapneumonic fluid and in 6 others by a twofold rise in optical density of serum antibody reactive to PsaA. Pneumococcal immunization had not previously been received by any patient; mortality was 22%. No additional cases were noted following administration of pneumococcal vaccine and antibiotic prophylaxis with penicillin or erythromycin. Twenty-six outbreaks of invasive pneumococcal disease since 1990 were reviewed. Twelve occurred in the United States, and serotypes 23F, 14, and 4 accounted for 8 (67%) of 12 outbreaks. All confirmed serotypes in US outbreaks are included in the 23-valent vaccine. More than one half of pneumococcal outbreaks worldwide involved elderly persons in hospitals or long-term-care facilities.

A pneumococcal pneumonia outbreak occurred among unvaccinated residents of a residential facility for the aged. Institutionalized elderly persons are at risk of outbreaks of pneumococcal disease and should be vaccinated.

In 1991, the Centers for Disease Control and Prevention devised the National Nosocomial Infection Surveillance (NNIS) System risk index to stratify populations of surgical patients by the risk of acquiring surgical-site infections (SSIs).

To determine whether the NNIS risk index adequately stratifies a population of cardiothoracic surgery patients by the risk of developing SSI.

Casecontrol study.

The University of Iowa Hospitals and Clinics, a 900-bed, midwestern, tertiary-care hospital.

201 patients with SSIs identified by prospective infection control surveillance and 398 controls matched by age, gender, type of procedure, and date of procedure. All patients underwent cardiothoracic operative procedures between November 1990 and January 1994.

The SSI rate was 7.8%. Seventy-four percent of cases and 80% of controls had a NNIS risk index score of 1; 24% of cases and 16% of controls had a score of 2 (P=.05). Patients with a NNIS risk score ≥2 were 1.8 times more likely to develop an SSI than those with a NNIS score <2 (odds ratio, 1.83; 95% confidence interval, 1.14-2.94, P=.01). The duration of the procedure was the only component of the index that stratified the population by risk of SSI.

The risk of SSI after cardiothoracic operations increases as the NNIS risk index score increases. However, this index only dichotomized the patient population on the basis of the procedure duration. More research is needed to develop a risk index that adequately stratifies the risk of SSI after cardiothoracic operations.

Investigation of an outbreak of influenza A in a neonatal intensive care unit (NICU) with examination of risk factors for infection and outcomes.

Retrospective cohort study of infants admitted to the unit during the outbreak period. Prospective survey of NICU staff and mothers of infants in the cohort study.

Level III nursery in a university-affiliated tertiary referral center.

Nineteen infants in the NICU were infected with influenza A. There were six symptomatic cases and one death who had evidence of virus-associated hemophagocytic syndrome at autopsy. Amantadine prophylaxis was offered to the NICU staff, and amantadine therapy was given to five of the six symptomatic infants. Mechanical ventilation, gestational age, birth weight, Clinical Risk Index for Babies score, and twin pregnancy were associated with acquisition of influenza A on univariate analysis. Mechanical ventilation (odds ratio [OR], 6.2; P=.02) and twin pregnancy (OR, 7.0; P=.04) remained as significant risk factors for infection on multiple logistic regression analysis. Only 15% of respondents to the NICU staff survey were vaccinated against influenza. There was no association between a history of an influenza-like illness during pregnancy and acquisition of influenza A by infants of mothers who responded to the maternal survey (OR, 0.91; P=1.0).

Influenza A is an important pathogen in the neonatal population and is readily transmissible in the NICU setting.

To investigate an outbreak of methicillin-susceptible Staphylococcus aureus (MSSA); infections in a neonatal clinic.

Prospective chart review, environmental sampling, and genotyping by two independent methods: pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). A case-control study was performed with 31 controls from the same clinic.

A German 1,350-bed tertiary-care teaching university hospital.

There was a significant increase in the incidence of pyodermas with MSSA 10 neonates in good physical condition with no infection immediately after birth developed pyodermas. A shared spatula and ultrasound gel were the only identified infection sources. The gel contained MSSA and was used for hip-joint sonographies in all neonates. PFGE and RAPD-PCR patterns from 6 neonates and from the gel were indistinguishable and thus genetically related clones. The case-control study revealed no significant risk factor with the exception of cesarean section (P=.006). The attack rate by days of hip-joint sonography between April 15 and April 27, 1994, was 11.8% to 40%.

Inappropriate hygienic measures in connection with lubricants during routine ultrasound scanning may lead to nosocomial S aureus infections of the skin. To our knowledge this source of S aureus infections has not previously been described.

To investigate the airflow characteristics of respiratory isolation rooms (IRs) and to evaluate the use of visible smoke as a monitoring tool.

Industrial hygienists from the New York State Department of Health evaluated 140 designated IRs in 38 facilities within New York State during 1992 to 1998. The rooms were located in the following settings: hospitals (59%), correctional facilities (40%), and nursing homes (1%). Each room was tested with visible smoke for directional airflow into the patient room (ie, negative air pressure relative to adjacent areas). Information was obtained on each facility's policies and procedures for maintaining and monitoring the operation of the IRs.

Inappropriate outward airflow was observed in 38% of the IRs tested. Multiple factors were associated with outward airflow direction, including ventilation systems not balanced (54% of failed rooms), shared anterooms (14%), turbulent airflow patterns (11%), and automated control system inaccuracies (10%). Of the 140 tested rooms, 38 (27%) had either electrical or mechanical devices to monitor air pressurization continuously. The direction of airflow at the door to 50% (19/38) of these rooms was the opposite of that indicated by the continuous monitors at the time of our evaluations. The inability of continuous monitors to indicate the direction of airflow was associated with instrument limitations (74%) and malfunction of the devices (26%). In one facility, daily smoke testing by infection control staff was responsible for identifying the malfunction of a state-of-the-art computerized ventilation monitoring and control system in a room housing a patient infectious with drug-resistant tuberculosis.

A substantial percentage of IRs did not meet the negative air pressure criterion. These failures were associated with a variety of characteristics in the design and operation of the IRs. Our findings indicate that a balanced ventilation system does not guarantee inward airflow direction. Devices that continuously monitor and, in some cases, control the pressurization of IRs had poor reliability. This study demonstrates the utility of using visible smoke for testing directional airflow of IRs, whether or not continuous monitors are used. Institutional tuberculosis control programs should include provisions for appropriate monitoring and maintenance of IR systems on a frequent basis, including the use of visible smoke.

To estimate the frequency of, and assess risk factors for, percutaneous, mucous membrane, and cutaneous blood contacts sustained by healthcare workers (HCWs) during the delivery of infusion therapy and the performance of procedures involving sharp instruments in the home setting.

Prospective surveillance of percutaneous, mucous membrane, and cutaneous blood contacts.

Eleven home healthcare agencies in the United States and Canada from August 1996 through June 1997.

HCWs who provided home infusion therapy or performed procedures using hollow-bore needles and other sharp instruments in the home setting.

Each participating worker recorded information about the procedures performed and blood contacts experienced during each of his or her home visits for a 2- to 4-week period using standard questionnaires. HCWs also completed questionnaires regarding job duties, reporting of previous occupational blood contacts, and their use of protective barriers in the home setting.

Participating HCWs provided information about 33,606 home visits. A total of 19,164 procedures were performed during 14,744 procedure visits. Fifty-three blood contacts occurred during these visits, for a blood-contact rate of 2.8 blood contacts per 1,000 procedures and 0.6 percutaneous injuries per 1,000 procedures with needles or lancets. Gloves were worn for 52%, masks for 5%, gowns for 3%, and protective glasses or goggles for 2% of all procedure visits. HCWs used barriers for 53% of visits during which at least 1 procedure was performed and for 27% of other visits.

HCWs involved in home health care are at risk for blood contact. Infection control barrier use was low in our study. The majority of skin contacts could have been prevented by glove use.