Risk factors for mortality among patients with nonperinatal listeriosis in Los Angeles County, 1992-2004.

BACKGROUND

Listeriosis is a relatively rare foodborne disease with significant public health implications. The causative pathogen, Listeria monocytogenes, grows well in refrigeration, is associated with a case-fatality rate of 20%, and causes an estimated 28% of all foodborne disease-related deaths. Nevertheless, data on the risk factors for listeriosis mortality are limited.

METHODS

Using the passive surveillance listeriosis database of the County of Los Angeles Department of Public Health, we conducted a 13-year retrospective cohort study to describe nonperinatal listeriosis mortality in Los Angeles County during the period 1992-2004. A nonperinatal listeriosis case was defined as one occurring in a nonpregnant person >42 days of age who resided in Los Angeles County and had a culture positive for L. monocytogenes.

RESULTS

Unconditional multivariable logistic regression analysis of 281 nonperinatal listeriosis cases with 29 main effects variables resulted in finding nonhematological malignancy (odds ratio [OR], 5.92; 95% confidence interval [CI], 1.85-18.9), alcoholism (OR, 4.63; 95% CI, 1.36-15.8), age 70 years (OR, 3.44; 95% CI, 1.50-7.87), steroid medication (OR, 3.34; 95% CI, 1.38-8.08), and kidney disease (OR, 2.94; 95% CI, 1.18-7.31) to be statistically significant risk factors for mortality. Other listeriosis mortality risk factors with adjusted odds ratios >1.5 included blood transfusion, asthma, black race, Asian race, use of antibiotics, hypertension, receipt of chemotherapy, and Hispanic race. Patients admitted to the hospital with a diagnosis of sepsis alone had the highest mortality (23.7%), whereas patients with cases of meningitis alone had the lowest mortality (3.13%).

CONCLUSIONS

The findings of this study should be used to help researchers and clinicians focus on specific risk factors to prevent nonperinatal listeriosis-related deaths.