Legionella detection and subgrouping in water air-conditioning cooling tower systems in Kuwait.

The main aim of the study was to test for the presence of Legionnaires' disease-causing microorganisms in air-conditioned buildings in Kuwait using molecular technologies. For this purpose, 547 samples were collected from 38 cooling towers for the analysis of Legionella pneumophila. These samples included those from water (n = 178), air (n = 231), and swabs (n = 138). Out of the 547 samples, 226 (41%) samples were presumptive positive for L. pneumophila, with L. pneumophila viable counts in the positive water samples ranging from 1 to 88 CFU/ml. Of the Legionella culture-positive samples, 204 isolates were examined by latex agglutination. These isolates were predominately identified as L. pneumophila serogroup (sg) 2-14. Using the Dresden panel of monoclonal antibodies, 74 representatives isolates were further serogrouped. Results showed that 51% of the isolates belonged to serogroup 7 followed by 1 (18%) and 3 (18%). Serogroups 4 (4%) and 10 (7%) were isolated at a lower frequency, and two isolates could not be assigned to a serogroup. These results indicate the wide prevalence of L. pneumophila serogroup 7 as the predominant serogroup at the selected sampling sites. Furthermore, the 74 L. pneumophila (sg1 = 13; sg3 = 13; sg4 = 3; sg7 = 38; sg10 = 5; sgX = 2) isolates were genotyped using the seven gene protocol sequence-based typing (SBT) scheme developed by the European Working Group for Legionella Infections (EWGLI). The results show that Legionella isolates were discriminated into nine distinct sequence typing (ST) profiles, five of which were new to the SBT database of EWGLI. Additionally, all of the ST1 serogroup 1 isolates were of the OLDA/Oxford subgroup. These baseline data will form the basis for the development of a Legionella environmental surveillance program and used for future epidemiological investigations.

Coinfection with Listeria monocytogenes potentlxtes the response of BALB/c mice against Leishmania major.

Protection against L. major is dependent on the stimulation of an anti-leishmanial T helper1 (Th1) response and the production of Interferon (IFN)-y. BALB/c mice develop a Th2 response and fatal infection with Leishmania major. Strategies that boost IL-12 production have shown to be protective. The innate response to Listeria monocytogenes is associated with IL-12 production. The co-infection of BALB/c mice with L. monocytogenes attenuates the course of L. major infection. Lesion sizes were smaller, and co-infected mice out-survived controls injected with L. major alone. The parasite load was reduced at site of injection, in draining lymph nodes (LN) and spleen. During the first week of infection, in-vitro Leishmania-restimulated LN cells from co-infected mice produced higher levels of IFN-7 and undetectable levels of IL-4 compared to controls. Significant IL-4 mRNA expression was detected in LN cells of control but not in co-infected mice.