Screening for latent tuberculosis in migrants-status quo and future challenges.

OBJECTIVES: To review the evidence that migrants from tuberculosis (TB) high-incidence countries migrating to TB low-incidence countries significantly contribute to active TB cases in the counties of destination, primarily through reactivation of latent TB. METHODS: This is a narrative review. The different screening programs in the countries of destination are reviewed either based on screening and preventive treatment of latent TB pre or more commonly - post arrival. RESULTS: Screening can be performed using interferon-gamma release assays (IGRA) or tuberculin skin tests (TST). Preventive treatment of latent TB is using either monotherapy with isoniazid, or in combination with rifampicin or rifapentine. We discuss the ethical issues of preventive treatment in asymptomatic individuals and how these are addressed in different screening programs. CONCLUSION: Screening migrants from TB high endemic countries to TB low endemic countries is beneficial. There is a lack of standardization and agreement on screening protocols, follow up and treatment.

Screening migrants from tuberculosis high-endemic countries for latent tuberculosis in Oman: A cross sectional cohort analysis.

To fulfil the World Health Organization (WHO) End TB strategy, screening for tuberculosis (TB) in immigrants is an important component of the strategy to reduce the TB burden in low-incidence countries. Oman has an annual TB incidence rate of 5.7 per 100000 and transmission from migrants with activated latent TB infection (LTBI) to nationals is a concern. The aim of this study was to determine the proportion of migrants to the Sultanate of Oman with LTBI. The study used an interferon-gamma release assay (IGRA) to assess previous exposure to TB, defining LTBI and a positive IGRA with a normal chest X-ray. 1049 subjects were surveyed. Six participants were excluded from the analysis as they had been recently vaccinated and 1 had an indeterminate result, thus 1042 subjects were included. The overall IGRA-positive rate was 22.4% (234/1042), 30.9% and 21.2% of African and Asian migrants, respectively, were IGRA-positive. Fifty-eight of the participants had a strong IGRA reactivity defined as more than 4 IU/ml. The study shows the proportion of migrants from Asia and Africa with LTBI and 24.7% (58/234) of IGRA-positive migrants had an IGRA of >4 IU/ml, defining a subpopulation with a high risk of developing active TB in the first two years of arrival to the country.

Tools to implement the World Health Organization End TB Strategy: Addressing common challenges in high and low endemic countries.

AIM: The purpose of this viewpoint is to summarize the advantages and constraints of the tools and strategies available for reducing the annual incidence of tuberculosis (TB) by implementing the World Health Organization (WHO) End TB Strategy and the linked WHO TB Elimination Framework, with special reference to Oman. METHODS: The case-study was built based on the presentations and discussions at an international workshop on TB elimination in low incidence countries organized by the Ministry of Health, Oman, which took place from September 5 to September 7, 2019, and supported by the WHO and European Society of Clinical Microbiology and Infectious Diseases (ESCMID). RESULTS: Existing tools were reviewed, including the screening of migrants for latent TB infection (LTBI) with interferon-gamma release assays, clinical examination for active pulmonary TB (APTB) including chest X-rays, organization of laboratory services, and the existing centres for mandatory health examination of pre-arrival or arriving migrants, including examination for APTB. The need for public-private partnerships to handle the burden of screening arriving migrants for active TB was discussed at length and different models for financing were reviewed. CONCLUSIONS: In a country with a high proportion of migrants from high endemic countries, screening for LTBI is of high priority. Molecular typing and the development of public-private partnerships are needed.

Effects of the Antimicrobial Peptide LL-37 and Innate Effector Mechanisms in Colistin-Resistant Klebsiella pneumoniae With mgrB Insertions.

BACKGROUND: Colistin is a polypeptide antibiotic drug that targets lipopolysaccharides in the outer membrane of Gram-negative bacteria. Inactivation of the mgrB-gene is a common mechanism behind colistin-resistance in Klebsiella pneumoniae (Kpn). Since colistin is a cyclic polypeptide, it may exhibit cross-resistance with the antimicrobial peptide LL-37, and with other innate effector mechanisms, but previous results are inconclusive. OBJECTIVE: To study potential cross-resistance between colistin and LL-37, as well as with other innate effector mechanisms, and to compare virulence of colistin-resistant and susceptible Kpn strains. MATERIALS/METHODS: Carbapenemase-producing Kpn from Oman (n = 17) were subjected to antimicrobial susceptibility testing and whole genome sequencing. Susceptibility to colistin and LL-37 was studied. The surface charge was determined by zeta-potential measurements and the morphology of treated bacteria was analyzed with electron microscopy. Bacterial survival was assessed in human whole blood and serum, as well as in a zebrafish infection-model. RESULTS: Genome-analysis revealed insertion-sequences in the mgrB gene, as a cause of colistin resistance in 8/17 isolates. Colistin-resistant (Col-R) isolates were found to be more resistant to LL-37 compared to colistin-susceptible (Col-S) isolates, but only at concentrations ≥50 µg/ml. There was no significant difference in surface charge between the isolates. The morphological changes were similar in both Col-R and Col-S isolates after exposure to LL-37. Finally, no survival difference between the Col-R and Col-S isolates was observed in whole blood or serum, or in zebrafish embryos. CONCLUSION: Cross-resistance between colistin and LL-37 was observed at elevated concentrations of LL-37. However, Col-R and Col-S isolates exhibited similar survival in serum and whole blood, and in a zebrafish infection-model, suggesting that cross-resistance most likely play a limited role during physiological conditions. However, it cannot be ruled out that the observed cross-resistance could be relevant in conditions where LL-37 levels reach high concentrations, such as during infection or inflammation.

The epidemiology and outcomes of infective endocarditis in a tertiary care hospital in Oman.

OBJECTIVES: We undertook this study to describe the epidemiological and clinical features of infective endocarditis (IE) and to study the complications and management of IE in a tertiary care hospital in Oman. METHODS: This is a retrospective study of 58 adult patients (>13 years of age) admitted to the Royal Hospital with IE from June 2006 to June 2011. RESULTS: Of the 58 patients, 40 (69%) were males, and 18 (31%) were females (ratio 2.2). The median age was 43.6 years (range: 14-85). Forty-eight cases (82.7%) had native valves, nine patients (15.6%) had prosthetic valves, and one case (1.7%) had a pacemaker. The most commonly involved valves were mitral (33, 56.9%) and aortic (23, 39.7%). The blood cultures were positive in 47 (81%) patients, and the most commonly isolated organisms were Streptococci spp., which were found in 20 (34.5%) patients, and Staphylococci spp., which were found in 19 (32.8%) patients. The complication rate was 21%. A total of 15 (25.9%) patients underwent surgical intervention, and the in-hospital mortality rate was 27.6%. CONCLUSIONS: Native-valve IE is the predominant type of endocarditis and is more of an acute disease. The prevalence of Staphylococci spp. IE is similar to that of Streptococci spp. IE, and its associated mortality remains high.