Evaluating the efficiency of specimen pooling for PCR-based detection of COVID-19

In the age of a pandemic, such as the ongoing one caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the world faces a limited supply of tests, personal protective equipment, and factories and supply chains are struggling to meet the growing demands. This study aimed to evaluate the efficacy of specimen pooling for testing of SARS-CoV-2 virus, to determine whether costs and resource savings could be achieved without impacting the sensitivity of the testing. Ten previously tested nasopharyngeal and throat swab specimens by real-time polymerase chain reaction (PCR), were pooled for testing, containing either one or two known positive specimens of varying viral concentrations. Specimen pooling did not affect the sensitivity of detecting SARS-CoV-2 when the PCR cycle threshold (Ct) of original specimen was lower than 35. In specimens with low viral load (Ct > 35), 2 of 15 pools (13.3%) were false negative. Pooling specimens to test for Coronavirus Disease 2019 infection in low prevalence (≤1%) areas or in low risk populations can dramatically decrease the resource burden on laboratory operations by up to 80%. This paves the way for large-scale population screening, allowing for assured policy decisions by governmental bodies to ease lockdown restrictions in areas with a low incidence of infection, or with lower-risk populations.     

Indinavir/ritonavir remains an important component of HAART for the treatment of HIV/AIDS, particularly in resource-limited settings

For over a decade, indinavir has been approved for the treatment of HIV/AIDS; however, following the introduction of new protease inhibitors (PIs) with improved safety and pharmacologic profiles, its use in developed countries has become almost obsolete. In contrast, in resource-limited settings where the majority of people living with HIV/AIDS reside, indinavir is part of the most affordable PI-based highly active antiretroviral treatment regimen. A major drawback of indinavir use is renal toxicity, but low-dose indinavir plus ritonavir (400/100 mg) twice daily is both efficacious and tolerable. Similar low dosing levels in children have also proven successful, but data in pregnant women remains limited. Due to its low cost and proven efficacy indinavir remains a key component of HIV/AIDS treatment in resource-limited settings.     

Reduction in mother-to-child transmission of HIV in Thailand, 2001-2003: Results from population-based surveillance in six provinces

BACKGROUND: In 2000, Thailand implemented a national program to prevent mother-to-child HIV transmission (PMTCT). OBJECTIVE: To describe the effectiveness of the prevention of mother-to-child HIV transmission program in Thailand. DESIGN AND METHODS: A register of HIV-exposed children at birth was created with follow-up of infection status. The register included children born to HIV-infected women between 1 January 2001 and 31 December 2003 at 84 public health hospitals in six provinces of Thailand. The main outcome measure was HIV infection in children. RESULTS: A total of 2200 children born to HIV-infected mothers were registered. Of these mother-infant pairs, 2105 (95.7%) received some antiretroviral prophylaxis, including 1358 (61.7%) who received the complete short-course zidovudine regimen during pregnancy and labor for the mother and after birth for the infant, with or without other antiretrovirals. HIV infection outcome was determined for 1667 (75.8%) children, of whom 158 [9.5%, 95% confidence interval (CI), 8.1-11.0%] were infected. Transmission risk was 6.8% (95% CI 5.2-8.9%) among 761 mother-infant pairs that received the complete zidovudine regimen alone, and 3.9% (95% CI, 2.2-6.6%) among 361 mother-infant pairs that received the complete zidovudine regimen combined with other antiretrovirals, usually nevirapine. The overall transmission risk from this cohort, including all antiretroviral prophylaxis combinations, is estimated to be 10.2%. CONCLUSIONS: The Thai national PMTCT program is effective in reducing mother-to-child transmission risk from the historical risk of 18.9-24.2%. The addition of nevirapine to short-course zidovudine beginning in 2004 may further improve program effectiveness in Thailand.     

Tuberculosis treatment with mobile-phone medication reminders in northern Thailand

Thailand's implementation of the Directly Observed Treatment, Short course (DOTS) strategy to increase tuberculosis (TB) control program efficacy has not achieved the World Health Organization (WHO) TB key targets. We defined two TB control models in the study. Patients in Model 1 were treated with a conventional DOTS strategy and in Model 2, patients were treated the same as Model method 1 but were given a phone call reminder to take their medication. Multi-drug resistant tuberculosis (MDR-TB) and non-MDR-TB patients were randomized into either Model 1 or 2. Treatment outcomes were given as cure rates, completion rates, failure rates or success rates at 18 months in the MDR-TB group and 6 months in the non-MDR-TB group. The sputum conversion rate at 1 month were evaluated for both groups. In the MDR-TB group, the sputum conversion rate was 20% (95% CI 8-45) in Model 1 and 90% (95% CI 73-98) in Model 2 (p < 0.001). In the non-MDR-TB group, the sputum conversion rate was 52% (95% CI 36-70) in Model 1 and 37% (95% CI 22-56) in Model 2 although the difference was not significant (p = 0.221). The Model 2 success rates were significantly higher (73.7%, 96.7%) in both the MDR-TB and non-MDR-TB groups (p < 0.001, p = 0.047). The MDR-TB rate in northern Thailand decreased from 4.1% during April-September 2008 to 1.8% during April-September 2009. Further study of the association between implementation of Model 2 and MDR-TB incidence reduction needs to be carried out.     

Unstable vancomycin heteroresistance is common among clinical isolates of methiciliin-resistant Staphylococcus aureus

We tested 109 unique, vancomycin-susceptible, methicillin-resistant Staphylococcus aureus (MRSA) strains for vancomycin heteroresistance by a selection method, i.e., step-wise exposure of large inoculums to increasing concentrations of vancomycin. Although no strains demonstrated stable heteroresistance, 81 strains (74%) demonstrated unstable heteroresistance. Unstable heteroresistance is common among clinical isolates of MRSA and may represent a cause of therapeutic failure.     

Evaluation of a practical method to assess antiretroviral adherence in HIV-infected Thai children

The objective of this study was to evaluate a practical method to assess adherence to antiretroviral therapy by observing virological and immunological responses. We conducted a 12-month longitudinal cohort study of 162 HIV-infected Thai children. Adherence was assessed using 5 methods (self reporting calendar, records of missed doses, pill counts, physician assessment, and an interview questionnaire). CD4 count, percentage and viral load were performed at baseline and at 12 months. Mean adherence rates at 2, 6, and 12 months were 98, 100, and 99% by the calendar method; 98, 100, and 100% by recording missed doses; 96, 96, and 92% by pill count; and 90, 94, and 97% by physician assessment. Poor agreement (kappa < or = 0.1) was found among the methods. There was a statistically significant difference (p = 0.05) in virological response between participants with > or = 95% adherence (0.8 log10) and those with < 95% adherence (0.2 log10) when pill counts were used to assess adherence. In conclusion, despite poor agreement among these tools, a pill count appeared to be the only practical, validated method to differentiate the virological outcome between those who were fully and partially adhere to the treatment regimen.