Six months ago, a 32-year-old Black African woman was seen for her routine review. She was asymptomatic. Approximately 13 to 14 months earlier, she was referred to our HIV Unit because of a low CD4 count for ART initiation. She was antiretroviral (ARV)-naïve with WHO clinical stage 3 (oral candidiasis) and a baseline CD4 count of 14 cells/mL. Reflex laboratory serum Cryptococcal Latex Antigen Test serology was negative. The results of other baseline investigations were within normal limits. Her symptom screen for tuberculosis was negative. Alcohol and substance use were excluded. There was no history of depression or any comorbid chronic illnesses. She disclosed her status to her partner. She was nulliparous.

Her medications during preparation for ARVs included co-trimoxazole, multivitamins and oral nystatin. She was commenced on a fixed dose combination of tenofovir, emtricitabine and efavirenz daily (according to the South African National Department of Health Guideline, 2013) [4]. She was followed up at 2, 4 and 8 weeks for immune reconstitution inflammatory syndrome and adverse effects. At each visit, adherence was reviewed and further counselling was provided. Isoniazid prophylaxis was initiated; her estimated glomerular filtration rate was normal at three months (glomerular filtration rate >60 mL/minute/1.73m2).

She was again reviewed at six months in 2014: viral load (VL) of 31,397 ribonucleic acid (RNA) copies/mL; a log value of 4 was obtained. Poor adherence was considered despite her and the treatment supporter’s account of good adherence. A thorough evaluation of the medical files for clinic attendance, pharmacy records for pick-up of medications and pill count charts was conducted. She was deemed to have a relatively good adherence. There were no drug–drug interactions; no herbal or alternative therapies were used during the period of treatment. She was not treated for diarrhoea or vomiting during the preceding 6 months. Further questions about her new sexual partner and HIV status of previous sexual partners did not yield any new information and she had not been sexually active since diagnosis of HIV. Adherence was consolidated for another two months with intense monthly review. Her VL at eight month remained 31,159 RNA copies/mL in spite of excellent adherence. We confirmed virological failure. An assessment of a probable primary virological failure from TDRHIV was considered. A decision was made to switch to a second-line regimen of zidovudine (AZT)/lamivudine/lopinavir and ritonavir at standard doses.

After analysing the case we decided to do an HIV drug genotypic test outside the National guideline to understand the pattern of resistant mutation in our patient.

The genotypic test result showed susceptibility to protease inhibitors and AZT (Table 1).

Table 1 Mutation score of patient Full size table

The HIV subtype isolated in the genotypic testing was subtype C. The K65R mutation was noted as part of the nucleoside/nucleotide reverse-transcriptase inhibitor mutation; however, AZT remains active.

She was reviewed monthly and a blood sample for VL was taken at third month of commencing second-line ARVs. The result confirmed viral suppression (VL=25 RNA copies/mL). She is presently doing well.

The timeline of the case is shown in Figure 1.