Investigation of a cluster of Legionella pneumophila infections among staff at a federal research facility.

An epidemiologic investigation was conducted in response to a case of Legionella pneumonia in a scientist working at a federal research facility. A survey of 80 individuals working at the facility revealed that 13 (16%) had sustained prior infections with Legionella pneumophila serogroup 1 (Lps1) as measured by anti-Lps1 antibodies. Antibody-positive individuals' offices clustered around an air cooling tower and a heating, ventilation, and air conditioner unit (odds ratio = 5). On multivariate logistic regression analysis, individuals of non-white race (adjusted odds ratio = 8) and smokers (adjusted odds ratio = 36) were also found to be at higher risk of past infection. Marked Legionella growth was noted in the cooling tower's water reservoir and potable hot water system, where suboptimal operating temperatures were noted. Subsequent increase in the hot water temperatures as well as a complete renovation of the affected building's air handling and potable water systems led to a reduction in Legionella species colonization.

Detection of adenoviruses (AdV) in culture-negative environmental samples by PCR during an AdV-associated respiratory disease outbreak.

Since 1954, adenoviruses (AdV) have been recognized as an important cause of acute respiratory disease (ARD) among U.S. military recruits. Until recently, routine oral vaccination for AdV serotypes 4 and 7 eliminated epidemic AdV-associated ARD in this population. Now that the manufacturer has ceased production, vaccination has ended and AdV epidemics have reappeared. As part of a prospective epidemiological study during the high-risk ARD season, serial samples were obtained from ventilation system filters and tested for AdV by culture and PCR. An outbreak occurred during this surveillance. Of 59 air filters, 26 (44%) were AdV positive only by PCR. Sequence analysis confirmed the presence of AdV serotype 4, the implicated outbreak serotype. The number of AdV-related hospitalizations was directly correlated with the proportion of filters containing AdV; correlation coefficients were 0.86 (Pearson) and 0.90 (Spearman's rho). This is the first report describing a PCR method to detect airborne AdV during an ARD outbreak. It suggests that this technique can detect and quantify AdV-associated ARD exposure and may enable further definition of environmental effects on AdV-associated ARD spread.

An outbreak of Shigella dysenteriae type 2 among laboratory workers due to intentional food contamination.

CONTEXT: Shigella dysenteriae type 2 is rare in the United States, and outbreaks associated with this pathogen are uncommon. OBJECTIVE: To determine the magnitude and source of an outbreak of S dysenteriae type 2. DESIGN: Retrospective cohort. SETTING: Laboratory of a large medical center. PATIENTS: Case patients were identified as laboratory workers who had diarrhea on or after October 28 and a positive stool culture or temperature greater than 37.8 degrees C. Laboratory workers with diarrhea only were probable case patients. MAIN OUTCOME MEASURES: We interviewed laboratory staff and performed identification, serotyping, and pulsed-field gel electrophoresis on isolates from case patients, implicated food, and laboratory stock culture. RESULTS: From October 29 through November 1, a total of 12 (27%) of 45 laboratory staff developed severe, acute diarrheal illness; 8 had S dysenteriae isolated from stool and 4 were hospitalized. All case patients reported having eaten muffins or doughnuts placed in the staff break room on October 29. Pulsed-field gel electrophoresis showed stool isolates from 9 case patients were indistinguishable from S dysenteriae type 2 recovered from an uneaten muffin and from the laboratory's stock strain, a portion of which was missing. CONCLUSIONS: The source of the outbreak was most likely the laboratory's stock culture, which was used to contaminate the pastries. Results of this investigation underscore the need for adequate precautions to prevent inadvertent or intentional contamination from highly pathogenic laboratory specimens.

The level of cariogenic micro-organisms in patients with Sjögren's syndrome.

Sixteen patients with caries-inactive sjögren's syndrome with low parotid salivary flow rates (< 0.25 mL/min) and 18 caries-inactive control subjects with higher salivary flow rates were compared. Mutans streptococci (MS) and lactobacilli (LB) counts were measured by means of Dentocult SM strip mutans and LB assays. The group with Sjögren's syndrome displayed higher counts of MS (P = 0.014) and LB (p = 0.003) when compared with controls. The results of this study indicate that patients with caries-inactive Sjögren's syndrome and low salivary flow may have higher colonization of cariogenic micro-organisms than healthy individuals.