Page 315 - SAHCS HIVMed Journal Vol 20 No 1 2019

Page 4 of 7 Original Research

interval [CI] 1.37–4.14) (p = 0.002) (Table 3). A neutrophil suspected immune reconstitution syndrome after having
count ≤ 0.5 × 10 /L was found more commonly in those with been on ART for 3 months.
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a unique diagnosis (p = 0.05); however, the numbers in this
group were too small to interpret correctly. Discussion

Diagnosis of mycobacterial infection In the current study, the cohort comprised patients from
on bone marrow examination an ID ward at a tertiary level referral hospital covering a
population of over 4 million individuals from central and
Of the 327 bone marrow investigations performed, northern Johannesburg. A total of 327 bone marrow
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microbiological confirmation of MTB and MAC were made investigations were performed during the 3-year study
in 54 and 4 cases, respectively. Of the 226 bone marrow period. This sample size is larger per time period compared
mycobacterial cultures performed 55 yielded positive results to international studies which, on average, have taken longer
(24.3%). Of the 182 ZN stains performed 51 yielded positive to review similar numbers viz. 8 to 9 years. 5,6,11 This difference
results (28.0%). Six MTB PCRs were commented on as may be accounted for by the high burden of HIV infection
positive; however, it was not noted how many MTB PCR and tuberculosis in this region compared to developed
tests were performed that yielded negative results, and thus countries.
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comparisons could not be performed. A WCC ≤ 4 × 10 /L and
a CD4 cell count ≤ 50 cells/mm were found to be significant The mean age of the study population was 36 years (17–65
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predictors of a microbiologically confirmed diagnosis of a years), with 96% of these individuals being HIV-seropositive.
mycobacterial infection (including MTB and MAC) on BME This reflects the high burden of HIV infection in the South
(Table 4). African public sector. The median CD4 cell count at
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admission was 47 cells/mm (1 cells/mm – 1069 cells/mm )
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3
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There were seven patients with the diagnosis of MAC in reflecting not only delayed health-seeking behaviour but also
the study population. In three of these patients, the BME the higher morbidity in those with advanced stages of HIV
was not diagnostic and MAC was found on a positive infection and CD4 cell counts < 200 cells/mm. 3,19 Such
peripheral blood culture alone. Of the remaining four patients with lower CD4 cell counts are more likely to have
patients with MAC in the study population, one cultured clinically advanced disease and a lower anticipated survival
MAC on bone marrow culture alone, namely a diagnosis rate. At the time of the BME, 40.8% of patients were already
unique to the BME. Amongst the other three patients, both on ART. The low CD4 counts noted on presentation to a
the bone marrow and peripheral blood cultures were hospital despite being on ART suggest that these individuals
positive for MAC. In two of these cases, MAC was cultured were either being treated unsuccessfully or that their ART
faster on bone marrow than peripheral blood culture had been initiated at a late stage in their clinical decline. The
(unique diagnoses) and in one case MAC was cultured number of patients on ART at the time of this study is higher
faster on peripheral blood hence not a unique diagnosis. than the 23% of patients on ART found in the study by Van
This resulted in three of the four cases of MAC diagnosed Schalkwyk et al. between 2004 and 2007. This difference can
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on bone marrow culture that were unique to the BME. In all be accounted for by the expanded rollout of ART from 2004
the cases of MAC, the CD4 cell counts were ≤ 35 cells/mm . onwards. Only n = 12 (4%) of the cohort was HIV-uninfected.
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Four of the five patients who were on ART at the time This small number did not permit meaningful comparisons
had virological failure and one of the five presented as a between the HIV-seronegative and HIV-seropositive groups.
TABLE 3: Predictors of a unique diagnosis on bone marrow examination.
Variable Unique diagnosis (n = 77) Not a unique diagnosis (n = 250) p Odds ratio 95% CI
n % n %
HIV positive 75 97.4 239 95.6 0.57 1.56 0.33–7.32
Male sex 40 51.9 122 48.8 0.65 1.12 0.67–1.88
Hb (≤ 7 g/dL) 32 41.6 95 38.0 0.58 1.16 0.69–1.95
Platelet count (≤ 150 × 10 /L) 52 67.5 177 70.8 0.58 0.86 0.50–1.49
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WCC (≤ 4 × 10 /L) 55 71.4 128 51.2 0.002 2.38 1.37–4.14
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Neutrophil count (≤ 0.5 × 10 /L) 5 6.5 5 2.0 0.05 3.55 1.00–12.67
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CD4 (≤ 50 cells/mm ) 3 41 53.2 121 48.4 0.62 1.13 0.67– 1.92
WCC, white cell count; Hb, haemoglobin; CD4, cluster of differentiation 4; CI, confidence interval.
TABLE 4: Predictors of mycobacterial infection on bone marrow examination.
Variable Mycobacterial infection proven (n = 60) Not proven mycobacterial infection (n = 267) p Odds ratio 95% CI
n % n %
Hb (≤ 7 g/dL) 24 40.0 106 39.7 0.97 1.01 0.57–1.61
Platelet count (≤ 150 x 10 /L) 43 71.7 186 69.7 0.76 1.10 0.59–2.05
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WCC (≤ 4 x 10 /L) 42 70.0 140 52.4 0.01 2.11 1.15–3.87
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CD4 (≤ 50 cells/mm ) 3 40 66.8 124 46.4 0.005 2.37 1.28–4.41
WCC, white cell count; Hb, haemoglobin; CD4, cluster of differentiation 4; CI, confidence interval.
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