Typhoidal salmonella disease in Mukuru informal settlement, Nairobi Kenya; carriage, diversity, and antimicrobial resistant genes.

INTRODUCTION: Multiple studies have shown that typhoid fever is endemic in developing countries characterized by poor hygiene. A unique way of Salmonella Typhi (S.Typhi) pathogenicity is establishing a persistent, usually asymptomatic carrier state in some infected individuals who excrete large numbers of bacteria in faeces. This study aimed to determine the isolation rate of S.Typhi from blood and stool samples among cases and asymptomatic individuals in the Mukuru informal settlement and identify antibiotic resistance patterns within the same population. MATERIALS AND METHODS: We recruited 1014 outpatient participants presenting with typhoid-like symptoms in selected health centres in Nairobi, Kenya. Bacterial isolation was done on Xylose Lysine Deoxycholate agar (XLD) and Mac Conkey agar (Oxoid), followed by standard biochemical tests. Identification was done using API20E, and S.Typhi was confirmed by serotyping using polyvalent antisera 0-9 and monovalent antisera d. The Kirby-Bauer disc diffusion method was used to test the antimicrobial susceptibility of S.Typhi isolates, while Multi-Drug Resistant (MDR) strains were characterized using conventional PCR. RESULTS: Of 1014 participants, 54 (5%) tested positive for S.Typhi. Thirty-eight (70%) of the S.Typhi isolated were from stool samples, while sixteen (30%) were from blood. Three (0.2%) of the isolates were from asymptomatic carriers. Of the 54 S.Typhi isolates, 20 (37%) were MDR. Resistance to ciprofloxacin and nalidixic acid was 43% and 52%, respectively. Resistance to amoxicillin-clavulanic acid (a beta-lactam inhibitor) was 2%. The BlaTEM-1 gene was present in 19/20 (95%) MDR isolates. CONCLUSION: MDR S.Typhi is prevalent in Mukuru Informal settlement. The sharp increase in nalidixic acid resistance is an indication of reduced susceptibility to fluoroquinolones, which are currently the recommended drugs for the treatment of typhoid fever. This study highlights the need for effective antimicrobial stewardship and routine surveillance of antimicrobial resistance (AMR) to inform policy on the prevention and control of MDR Typhoid disease.

Comparison of the performance of Aptima HIV-1 Quant Dx Assay with Abbott RealTime HIV Assay for viral load monitoring using plasma and Dried Blood Spots collected in Kenya.

INTRODUCTION: HIV-1 viral Load (VL) testing is recommended for the monitoring of antiretroviral treatment. Dried Blood Spots (DBS) are an effective sample type in resource limited settings, where safe phlebotomy and reliable shipping are hard to guarantee. In HIV high burden countries, high throughput assays can improve access to testing services. The Hologic Aptima HIV-1 Quant Dx Assay (Aptima Assay) is a high throughput assay that runs on the CE-IVD approved Panther platform. The objectives of this study were to assess the performance characteristics of Aptima for VL monitoring using plasma and venous DBS specimens and to determine the stability of HIV-1 RNA in DBS. MATERIALS AND METHODS: This was a cross-sectional study of 2227 HIV infected adults visiting health facilities in Nairobi and Busia, Kenya. Each provided a venous blood sample; plasma was prepared from 1312 samples while paired DBS samples and plasma were prepared from the remaining 915 samples. The agreement between the Aptima assay and the Abbott RealTime HIV-1 Assay (Abbott RT) was analysed by comparing the HIV-1 VL in both assays at the medical decision point of 1000 copies/mL. To assess stability of HIV-1 RNA in DBS, VL in DBS spotted on day 0 were compared with that from the same DBS card after 21 days of storage at room temperature. RESULTS: Overall, 436 plasma samples had quantifiable results in both Aptima and Abbott RT. The agreement between the two assays at 1000 copies/mL was 97.48% with a Pearson's correlation coefficient (r) of 0.9589 and gave a mean bias of 0.33 log copies/mL on Bland-Altman analysis. For fresh DBS, the agreement in both assays was 94.64% at 1000 copies/mL, with an r of 0.8692 and a mean bias of 0.35 log copies/mL. The overall agreement between DBS tested in Aptima on day 0 versus day 21 was 95.71%, with a mean bias of -0.154. CONCLUSION: The Aptima HIV-1 Quant Dx assay is an accurate test for VL monitoring of HIV-1 using DBS and plasma sample types in Kenya.