Genomic characterization of the most barotolerant Listeria monocytogenes RO15 strain compared to reference strains used to evaluate food high pressure processing

BackgroundHigh pressure processing (HPP; i.e. 100-600MPa pressure depending on product) is a non-thermal preservation technique adopted by the food industry to decrease significantly foodborne pathogens, including Listeria monocytogenes, from food. However, susceptibility towards pressure differs among diverse strains of L. monocytogenes and it is unclear if this is due to their intrinsic characteristics related to genomic content. Here, we tested the barotolerance of 10 different L. monocytogenes strains, from food and food processing environments and widely used reference strains including clinical isolate, to pressure treatments with 400 and 600MPa. Genome sequencing and genome comparison of the tested L. monocytogenes strains were performed to investigate the relation between genomic profile and pressure tolerance.ResultsNone of the tested strains were tolerant to 600MPa. A reduction of more than 5 log(10) was observed for all strains after 1min 600MPa pressure treatment. L. monocytogenes strain RO15 showed no significant reduction in viable cell counts after 400MPa for 1min and was therefore defined as barotolerant. Genome analysis of so far unsequenced L. monocytogenes strain RO15, 2HF33, MB5, AB199, AB120, C7, and RO4 allowed us to compare the gene content of all strains tested. This revealed that the three most pressure tolerant strains had more than one CRISPR system with self-targeting spacers. Furthermore, several anti-CRISPR genes were detected in these strains. Pan-genome analysis showed that 10 prophage genes were significantly associated with the three most barotolerant strains.ConclusionsL. monocytogenes strain RO15 was the most pressure tolerant among the selected strains. Genome comparison suggests that there might be a relationship between prophages and pressure tolerance in L. monocytogenes.Peer reviewe

Hepatotoxicity from first line antiretroviral therapy: an experience from a resource limited setting

Background: Highly active antiretroviral therapy (HAART) has been associated with liver toxicity. The role of monitoring for liver toxicity has not been well studied in resource-limited settings (RLS). Objectives: To determine the background prevalence and incidence of liver injury and describe the associated signs and symptoms of acute hepatitis after initiating HAART; and to determine the role of liver enzyme tests in monitoring hepatotoxicity. Methods: In this prospective study, in Mulago Hospital AIDS Clinics, we consecutively enrolled adult patients initiated on one of three first line HAART regimens [Stavudine (d4T)-Lamivudine (3TC) and nevirapine (NVP); Zidovudine (AZT)-3TC and Efavirenz (EFV) or d4T-3TC-EFV]. We monitored ALT (alanine aminotransferase) and clinical evidence of acute hepatitis at baseline, 2nd, 6th, 10th and 14th week of therapy. Results: Two hundred and forty HIV-positive HAART- naïve patients were enrolled in the study. The baseline prevalence of transaminitis was 1.7% with an incidence of 4.2% at 14 weeks. Grade 3-4 hepatotoxicity was documented in 1.3%. Jaundice was seen in grade 2-4 ALT elevations. Being on concurrent HAART and antituberculous drugs was associated with grade 2-4 toxicity compared to those who were only on HAART [OR; 16.0 (95% CI; 2.4-104.2)]. Conclusions: Incidence of severe hepatotoxicity within three months of first-line antiretroviral therapy was low, suggesting that routine measurement of transaminases may not be necessary in all patients initiating HAART in RLS. Routine measurement may be important in following patients on HAART and concurrent TB treatment as well as those with jaundice to avoid missing hepatotoxicity