Multistate outbreak of Escherichia coli O145 infections associated with romaine lettuce consumption, 2010

Non-O157 Shiga toxin-producing Escherichia coli (STEC) can cause severe illness, including hemolytic uremic syndrome (HUS). STEC O145 is the sixth most commonly reported non-O157 STEC in the United States, although outbreaks have been infrequent. In April and May 2010, we investigated a multistate outbreak of STEC O145 infection. Confirmed cases were STEC O145 infections with isolate pulsed-field gel electrophoresis patterns indistinguishable from those of the outbreak strain. Probable cases were STEC O145 infections or HUS in persons who were epidemiologically linked. Case-control studies were conducted in Michigan and Ohio; food exposures were analyzed at the restaurant, menu, and ingredient level. Environmental inspections were conducted in implicated food establishments, and food samples were collected and tested. To characterize clinical findings associated with infections, we conducted a chart review for case patients who sought medical care. We identified 27 confirmed and 4 probable cases from five states. Of these, 14 (45%) were hospitalized, 3 (10%) developed HUS, and none died. Among two case-control studies conducted, illness was significantly associated with consumption of shredded romaine lettuce in Michigan (odds ratio [OR] = undefined; 95% confidence interval [CI] = 1.6 to undefined) and Ohio (OR = 10.9; 95% CI = 3.1 to 40.5). Samples from an unopened bag of shredded romaine lettuce yielded the predominant outbreak strain. Of 15 case patients included in the chart review, 14 (93%) had diarrhea and abdominal cramps and 11 (73%) developed bloody diarrhea. This report documents the first foodborne outbreak of STEC O145 infections in the United States. Current surveillance efforts focus primarily on E. coli O157 infections; however, non-O157 STEC can cause similar disease and outbreaks, and efforts should be made to identify both O157 and non-O157 STEC infections. Providers should test all patients with bloody diarrhea for both non-O157 and O157 STEC.

Tuberculosis in the inner city: impact of a continuing epidemic in the 1990s

Tuberculosis cases have recently declined in the United States, renewing interest in disease elimination. We examined the epidemiology of tuberculosis from 1991 through 1997 at an inner-city public hospital and assessed population-based tuberculosis rates by ZIP code in the 8 metropolitan Atlanta counties. During the 7 years, 1378 new patients had tuberculosis diagnosed at our hospital (mean, 197 patients/year), accounting for 25% of tuberculosis cases in Georgia. Coinfection with human immunodeficiency virus (HIV) was common, but a significant decrease in the proportion of HIV-infected patients with tuberculosis was noted over time. Most patients were members of a minority group (93%) and were born in the United States (96%). Two inner-city ZIP code areas had annual tuberculosis rates >120 cases per 100,000 persons, and 8 ZIP code areas had annual rates of 47-88 cases per 100,000 persons between 1993 and 1997, compared with the annual national average of 8.7 cases per 100,000 persons. Our hospital continues to care for large numbers of tuberculosis patients, and rates of tuberculosis remain high in the inner city. These data mandate a concentration of efforts and resources in urban locations if tuberculosis control and elimination is to be achieved in the United States.

Nosocomial tuberculosis exposure in an outpatient setting: evaluation of patients exposed to healthcare providers with tuberculosis

OBJECTIVE

To evaluate the risk of tuberculosis (TB) transmission to patients potentially exposed to two healthcare providers who worked in outpatient settings for several weeks prior to being diagnosed with acid-fast bacilli smear-positive pulmonary TB.

DESIGN

Potentially exposed patients were notified by letter and television reports of the recommended evaluation for TB infection or disease and availability of free screening at the hospital. Prevalence of infection in the screened patients and the incidence rate of TB over the subsequent 2 years were compared to those of a control group of unexposed outpatients.

SETTING

An urban inner-city hospital.

PATIENTS

1,905 patients with potential exposure to the ill healthcare workers; 487 (25%) presented for evaluation. Controls consisted of 951 unexposed patients.

RESULTS

361 potentially exposed patients had their tuberculin test read; 97 (27%) had a purified protein derivative > or = 10 mm. In the comparison group, 148 (25%) of 600 with test readings had a > or = 10-mm reaction (risk ratio, 1.18; 95% confidence interval, 0.86-1.60). In multivariate analysis, male gender, non-white race, and older age were significantly associated with a positive tuberculin test; exposure was not. No TB cases were identified during screening. Two years after the exposure, 7 TB cases had been reported to the state registry among 1,905 potentially exposed patients (184 cases/100,000 person-years) versus 4 cases in the comparison group of 951 (210 cases/100,000 person-years).

CONCLUSIONS

Evaluation of patients exposed to healthcare workers with TB disease in ambulatory settings of an inner-city hospital revealed no evidence of transmission of Mycobacterium tuberculosis due to the exposure.

Epidemiology of device-associated infections related to a long-term implantable vascular access device

OBJECTIVE

To examine risk factors for, and determine the incidence of, device-associated infections among patients with an implantable vascular access device.

SETTING

Grady Health System, including a 1,000-bed, inner-city, public, teaching hospital and human immunodeficiency virus (HIV), oncology, and sickle cell clinics in Atlanta, Georgia.

PATIENTS

123 consecutive patients who received a PAS-Port implantable venous access device between January 1 and June 30, 1995.

DESIGN

Retrospective cohort study with follow-up > or = 1 year following device implantation.

RESULTS

Underlying illnesses included HIV infection in 66 patients (median CD4 count, 24.4 cells/mm3), malignancy in 51, and sickle cell disease in 6. Mean age of patients was 43.7 years, 50% were male, and 74% were black. Thirty-one (25%) of 123 patients developed a primary or device-associated bloodstream infection (BSI), and 3 of the 31 patients experienced two separate episodes of infection. The overall rate of infection was 1.23 primary BSIs per 1,000 device days. Patients with cancer had a lower rate of infection than those with HIV infection, but the difference was not statistically significant (0.96 vs 1.50 BSIs/1,000 device days; relative risk, 0.58; 95% confidence interval, 0.27-1.26). Subgroup analysis of patients with different malignancies indicated that infection rates differed according to type of cancer, and there was a trend for heterogeneity across the different cancer strata (P=.06). Gram-positive pathogens accounted for 60% of the pathogens recovered. Six (19%) of 31 patients who developed an infection did so within the first 14 days after implantation. In 11 (32%) of the 34 BSIs, the port required removal; two patient deaths were attributed to device-associated bacteremias (0.072 deaths/1,000 device days).

CONCLUSIONS

Approximately one fourth of patients who had a vascular access device implanted developed a primary BSI, but the overall infection rate (per 1,000 device days) was relatively low, even among those with HIV infection. Primary BSI rates in patients with vascular access devices appeared to differ according to the specific underlying illness.