Epidemiological, clinical, and microbiological characteristics of listeriosis in Qatar: A retrospective study

Listeria monocytogenes is a bacterium found in raw foods and water and causes severe infections in immunocompromised, pregnant women, and the elderly. Although the incidence of listeriosis is low, it is a life-threatening disease with a case-fatality rate of 20% to 30% and numerous complications, including central nervous system (CNS) infections and maternal-fetal transmission. The purpose of this study was to determine the epidemiology, clinical features, and outcomes of listeriosis in Qatar over 10 years.

This retrospective cohort study was conducted at Hamad Medical Corporation, the main public healthcare provider in Qatar, analyzing laboratory-confirmed L. monocytogenes bloodstream infections from May 1, 2011, to November 26, 2021. The data were collected from the electronic medical records system and included demographic data, clinical features, microbiology, management, and outcome. The study was approved by the Institutional Review Board (MRC-01-21-1023). The inclusion criteria for the study were positive blood cultures and clinical signs of infection. Descriptive statistics and comparative analyses were used in the statistical analyses.

The study involved 35 cases with a median age of 39 years and 77.14% female. Pregnancy-associated cases were 22.86% with high fetal morbidity, including 33.33% stillbirth and 55.56% preterm delivery. Twenty percent of the patients had clinical features of meningoencephalitis. Although the source of infection could not be determined, it is known that Listeria monocytogenes is most commonly transmitted through contaminated food products. All the isolates were sensitive to ampicillin, co-trimoxazole, and meropenem. The 30- and 90-day mortality rates were 2.86% and 14.26%, respectively, and age (60 years and above) and meningoencephalitis were independent predictors of mortality.

This study offers significant information about listeriosis in Qatar, characterized by a higher incidence of pregnancy-associated cases and a lower incidence of CNS involvement than in other countries. These findings also show the gaps in antimicrobial resistance surveillance and the foodborne transmission in the Middle East. Even though all mothers recovered fully, the adverse fetal outcomes stress the importance of preventive measures and enhanced food safety measures. Future research should focus on molecular characterization, source attribution, and antimicrobial resistance monitoring to enhance infection control and public health interventions, ultimately mitigating the impact of listeriosis in the region.