医学微生物学与诊断

Introduction: One of the most important and cost-effective public health interventions to reduce child mortality and morbidity is vaccination. Despite a continued global effort in providing vaccinations, there are still cases of inadequate vaccination coverage especially in low-income countries. With the high under-five mortality in Ethiopia (67 deaths per 1,000 live births), only 38.5% of the children (12 to 23 months) had received all the recommended vaccines. Hence, the purpose of this study was to assess factors influencing fully vaccination coverage among children aged 12 to 23 months in Debre Markos town.

Methods: A community based cross-sectional study was employed among 389 children aged 12-23 months in Debre Markos town from January 1, 2018 to February 1, 2018. Systematic random sampling technique was used to select the study participants. Data was collected using face to face interviewer administered structured questionnaires. Then, the collected data was entered, coded and cleaned into EPI Data version 3.1 and exported to SPSS version 20.0 for data analysis. Bivariate and multivariate logistic regression was done to assess the association of factors with full vaccination coverage. Adjusted odds ratios with 95% confidence intervals were calculated, and p-values<0.05 were considered to indicate statistical significance.

Results: This study revealed that fully vaccination coverage among children aged 12 to 23 months was 76.9%. Fully vaccination coverage was significantly associated with women’s level of education (AOR=1.2, 95%CI (1.41-2.42), place of delivery of the index child (AOR=3.28, 95%CI (1.38-3.67), maternal knowledge on vaccine and vaccine preventable disease (AOR=4.12, 95%CI (3.0-10.6) and ANC service utilization (AOR=5.04, 95%CI (1.35-12.06).

Conclusion: Fully vaccination coverage among children aged 12 to 23 months in the studied area was low. Therefore, health extension workers should work on improvements in women’s educational status, encourage mothers to have ANC follow-up and institutional delivery and they should discuss vaccination with mothers in order to improve their knowledge on vaccine preventable disease and the advantage of complete vaccination services.

Introduction: Community-acquired pneumonia (CAP) caused by M. pneumoniae affect 3%-10% of children. It is not possible to spot M. pneumoniae infection depending entirely on clinical signs and symptoms. Correct identification of M. pneumoniae infections is crucial to initiate proper antibiotic therapy. The role of culture is questionable as this organism is fastidious. Diagnostic accuracy of serology depends on the specimen collection time. IgM can usually be tracked within one week after the onset of clinical illness, followed by IgG two weeks later. Nucleic Acid Amplification Techniques (NAATs) are proved to be the “new gold standard”. Loop-Mediated Isothermal Amplification (LAMP) amplifies DNA of mycoplasma in less than an hour under isothermal conditions with the use of six primers in a single tube. The amplified products can be visualized by naked eye as turbidity or fluorescence.

Aim: To assess the diagnostic value of LAMP assay compared to serum Mycoplasma IgM for rapid detection of M. pneumoniae.

Materials and methods: A 6-months study was conducted on hospitalized children diagnosed with community acquired pneumonia (CAP) admitted to Cairo University specialized pediatric hospital (CUSPH). M. pneumoniae IgM was done on serum samples by RD-Ratio Diagnostics ELISA kit, Germany. LAMP assay was done on nasopharyngeal swabs using Loopampᵀᴹ RNA/DNA, Eiken Chemical, Japan. Kappa measure of agreement was calculated to assess the concordance between LAMP and Mycoplasma IgM.

Results: 90 hospitalized children with CAP were included in the study. Serum IgM was positive in 27(30%) of cases. LAMP assay was positive in 33 cases (36.7%). The sensitivity of LAMP was 85.2%, the specificity was 84.1%, PPV was 69.7%, NPV 93.0% with AUC=0.847. The agreement between serology and LAMP was good K=0.652 with 95% CI (0.487-0.816).

Conclusion: LAMP technique is a rapid, sensitive and specific method for diagnosis of M. pneumoniae. Combination of LAMP assay and serology may be optimal for the diagnosis of M. pneumoniae infection.

Introduction: Pneumocystis jirovecii Pneumonia (PCP) is a life-threatening disease in immunocompromised patients. The aim of this work is to demonstrate the contribution of molecular biology in diagnosis compared to conventional methods and we propose an adapted cut-off value for differentiating Pneumocystis colonization from infection using real-time PCR.

Methodology: This was a prospective study enrolled from April 2015 to December 2018 at the Laboratory of parasitology of Military Hospital of Tunis. All pulmonary secretions samples were analyzed using: May-Grunwald-Giemsa (MGG) and Gomori Grocott Modified MUSTO Coloring Technology (GG). Optimization of conventional PCR and real-time PCR were accomplished.

Results: During the study period, we collected 200 samples. The prevalence of the disease was 5% (10/200). MGG coloring didn’t discern vegetative forms of Pneumocystis jirovecii for all samples. Cysts were visualized by GG coloring for seven samples. Conventional PCR and Realtime PCR were positives for 10 samples with quantity of DNA going from one copy to 10⁴ copies per milliliter.

Conclusion: Molecular biology is more sensitive than techniques of coloring. Currently real-time PCR gives at the same time a quantitative and qualitative approach with a threshold of detection very low which allows differentiating between a simple colonization and an infestation.