John Tembo

Assessment of the Xpert MTB/RIF Assay for Diagnosis of Tuberculosis with Gastric Lavage Aspirates in Children in Sub-Saharan Africa: A Prospective Descriptive Study.

BACKGROUND Rapid and accurate diagnosis of pulmonary tuberculosis in children remains challenging because of difficulties in obtaining sputum samples and the paucibacillary nature of the disease. The Xpert MTB/RIF assay is useful for rapid diagnosis of childhood tuberculosis with sputum and nasopharyngeal samples. We assessed this assay for the detection of tuberculosis and multidrug resistant (MDR) tuberculosis with gastric lavage aspirate (GLA) samples in children admitted to hospital. METHODS We did a prospective study to assess the sensitivity and specificity of the Xpert MTB/RIF assay with GLA samples for the detection of pulmonary tuberculosis and MDR tuberculosis in new paediatric inpatient admissions at the University Teaching Hospital, Lusaka, Zambia. Children aged 15 years or younger were recruited between June, 2011, and May, 2012. GLA and sputum were analysed by standard smear-microscopy, mycobacterial growth indicator tube (MGIT) culture, MGIT drug-susceptibility testing, and the Xpert MTB/RIF assay. Sensitivity of the Xpert MTB/RIF assay was assessed with the Pearson χ(2) or Fishers exact test. FINDINGS Of 930 children, 142 produced sputum and GLA was obtained from 788 non-sputum producers. Culture-positive tuberculosis was identified in 58 (6·2%) of 930 children: ten from sputum producers and 48 from GLA of non-sputum producers. The sensitivity and specificity of the Xpert MTB/RIF assay were similar: sensitivity was 68·8% (95% CI 53·6-80·9) for GLA versus 90·0% (54·1-99·5; p=0·1649) for sputum samples; specificity was 99·3% (98·3-99·8) for GLA and 98·5% (94·1-99·7; p=0·2871) for sputum samples. The Xpert MTB/RIF assay detected an extra 28 tuberculosis cases compared with smear microscopy and was significantly more sensitive than smear microscopy for both sputum (90·0% [54·1-99·5] vs 30·0% [8·1-64·6], p=0·01) and GLA (68·8% [53·6-80·9] vs 25·0% [14·1-40·0], p<0·0001). The assay load did not differ significantly by sample type (p=0·791). 22 children were infected with HIV and tuberculosis and significant differences in assay performance could not be detected when stratifying by HIV status for either sample type. The Xpert MTB/RIF assay detected rifampicin resistance in three GLA samples: two confirmed as MDR tuberculosis and one false positive. INTERPRETATION Analyses of GLA samples with the Xpert MTB/RIF assay is a sensitive and specific method for rapid diagnosis of pulmonary tuberculosis in children who cannot produce sputum. The single site nature of our study invites caution. FUNDING European Commission, European Developing Countries Clinical Trials Partnership, and UBS Optimus Foundation.

Evaluation of the Xpert MTB/RIF Assay at a Tertiary Care Referral Hospital in a Setting Where Tuberculosis and HIV Infection Are Highly Endemic

BACKGROUND. There were 1.45 million deaths from tuberculosis in 2011. A substantial proportion of active pulmonary tuberculosis cases in countries where tuberculosis, human immunodeficiency virus (HIV) infection, and AIDS are highly endemic remain undiagnosed because of the reliance on sputum-smear microscopy. This study evaluated the performance of the Xpert MTB/RIF assay at a tertiary care referral center in Zambia, a country where the burden of tuberculosis and HIV infection is high. METHODS. A total of 881 adult inpatients admitted to University Teaching Hospital in Lusaka who were able to produce sputum were enrolled and analyzed in the study, irrespective of admission diagnosis. Sputum specimens were analyzed by fluorescence smear microscopy, the Xpert MTB/RIF assay, mycobacterial growth indicator tube (MGIT) culture,and MGIT drug-susceptibility testing. The sensitivity and specificity of the Xpert MTB/RIF assay were evaluated using culture as the gold standard. RESULTS. Culture-confirmed tuberculosis was found in 201 of 881 patients (22.8%). The specificity of the Xpert MTB/RIF assay was 95.0% (95% confidence interval [CI], 92.4%–96.8%),and the sensitivity was 86.1% (95% CI, 80.3%–90.4%). In sputum smear–negative, culture-positive cases, the assay was 74.7% sensitive (95% CI, 64.6%–82.8%), identifying 71 additional tuberculosis cases that were not detected by smear microscopy.A total of 18 of 111 patients with tuberculosis who were tested (16.2%) had multidrug-resistant (MDR) tuberculosis.The sensitivity and specificity of the Xpert MTB/RIF assay for detecting culture-confirmed, rifampicin-resistant tuberculosis was 81.3% (95% CI, 53.7%–95.0%) and 97.5% (95% CI,90.4%–99.6%), respectively. CONCLUSIONS. The Xpert MTB/RIF assay performs better than smear microscopy in an inpatient setting in a country where tuberculosis and HIV infection are highly endemic. Assessment of its usefulness and cost-effectiveness for increased detection of tuberculosis cases missed by sputum smear and for concomitant screening for MDR tuberculosis among adult inpatients attending tertiary care referral centers in other countries with a high burden of tuberculosis and HIV infection is warranted [corrected].

High rates of congenital cytomegalovirus infection linked with maternal HIV infection among neonatal admissions at a large referral center in sub-Saharan Africa.

BACKGROUND  Congenital cytomegalovirus (CMV) infection is the major infectious cause of birth defects and hearing loss globally. There is a growing recognition of the potential clinical impact of congenital CMV infections in high-seroprevalence settings. METHODS  A cross-sectional study of neonatal admissions at a large referral center in sub-Saharan Africa to determine the prevalence of both symptomatic and asymptomatic congenital CMV infection was performed. Real-time polymerase chain reaction was used to screen DNA-extracted sera, urine, and saliva, and an enzyme-linked immunosorbent assay was used to screen serum samples for anti-CMV immunoglobulin M. Multivariate binary logistic regression was used to identify risk factors associated with increased odds of congenital CMV infection. RESULTS  Congenital CMV was detected in 3.8% (15/395) of neonates. Among these infants, 6 of 15 (40%) presented with jaundice, 1 of whom also had petechiae. Congenital CMV infection was detected in 9 of 79 (11.4%; 95% confidence interval [CI], 6.1%-20.3%) neonates born to human immunodeficiency virus (HIV)-infected mothers, and both maternal HIV (odds ratio [OR], 6.661 [95% CI, 2.126-20.876], P = .001) and jaundice (OR, 5.701 [95% CI, 1.776-18.306], P = .003) were independently linked with significantly increased odds of congenital CMV infection. CONCLUSIONS  Congenital and early infant CMV infections may have important consequences for child health in sub-Saharan Africa and other high HIV and CMV seroprevalence populations globally.

Evaluation of the burden of unsuspected pulmonary tuberculosis and co-morbidity with non-communicable diseases in sputum producing adult inpatients

Background A high burden of tuberculosis (TB) occurs in sub-Saharan African countries and many cases of active TB and drug-resistant TB remain undiagnosed. Tertiary care hospitals provide an opportunity to study TB co-morbidity with non-communicable and other communicable diseases (NCDs/CDs). We evaluated the burden of undiagnosed pulmonary TB and multi-drug resistant TB in adult inpatients, regardless of their primary admission diagnosis, in a tertiary referral centre. Methodology/Principal Findings In this prospective study, newly admitted adult inpatients able to produce sputum at the University Teaching Hospital, Lusaka, Zambia, were screened for pulmonary TB using fluorescent smear microscopy and automated liquid culture. The burden of pulmonary TB, unsuspected TB, TB co-morbidity with NCDs and CDs was determined. Sputum was analysed from 900 inpatients (70.6% HIV infected) 277 (30.8%) non-TB suspects, 286 (31.8%) TB suspects and 337 (37.4%) were already receiving TB treatment. 202/900 (22.4%) of patients had culture confirmed TB. TB co-morbidity was detected in 20/275 (7.3%) NCD patients, significantly associated with diabetes (P = 0.006, OR 6.571, 95%CI: 1.706–25.3). 27/202 (13.4%) TB cases were unsuspected. There were 18 confirmed cases of MDR-TB, 5 of which were unsuspected. Conclusions/Significance A large burden of unsuspected pulmonary TB co-morbidity exists in inpatients with NCDs and other CDs. Pro-active sputum screening of all inpatients in tertiary referral centres in high TB endemic countries is recommended. The scale of the problem of undiagnosed MDR-TB in inpatients requires further study.

Burden of tuberculosis at post mortem in inpatients at a tertiary referral centre in sub-Saharan Africa: a prospective descriptive autopsy study

BACKGROUND Patients with subclinical tuberculosis, smear-negative tuberculosis, extrapulmonary tuberculosis, multidrug-resistant tuberculosis, and asymptomatic tuberculosis are difficult to diagnose and may be missed at all points of health care. We did an autopsy study to ascertain the burden of tuberculosis at post mortem in medical inpatients at a tertiary care hospital in Lusaka, Zambia. METHODS Between April 5, 2012, and May 22, 2013, we did whole-body autopsies on inpatients aged at least 16 years who died in the adult inpatient wards at University Teaching Hospital, Lusaka, Zambia. We did gross pathological and histopathological analysis and processed lung tissues from patients with tuberculosis through the GeneXpert MTB/RIF assay to identify patients with multidrug-resistant tuberculosis. The primary outcome measure was specific disease or diseases stratified by HIV status. Secondary outcomes were missed tuberculosis, multidrug-resistant tuberculosis, and comorbidities with tuberculosis. Data were analysed using Pearson χ(2), the Mann-Whitney U test, and binary logistic regression. FINDINGS The median age of the 125 included patients was 35 years (IQR 29-43), 80 (64%) were men, and 101 (81%) were HIV positive. 78 (62%) patients had tuberculosis, of whom 66 (85%) were infected with HIV. 35 (45%) of these 78 patients had extrapulmonary tuberculosis. The risk of extrapulmonary tuberculosis was higher among HIV-infected patients than among uninfected patients (adjusted odds ratio 5·14, 95% CI 1·04-24·5; p=0·045). 20 (26%) of 78 patients with tuberculosis were not diagnosed during their life and 13 (17%) had undiagnosed multidrug-resistant tuberculosis. Common comorbidities with tuberculosis were pyogenic pneumonia in 26 patients (33%) and anaemia in 15 (19%). INTERPRETATION Increased clinical awareness and more proactive screening for tuberculosis and multidrug-resistant tuberculosis in inpatient settings is needed. Further autopsy studies are needed to ascertain the generalisability of the findings. FUNDING UBS Optimus Foundation, EuropeAID, and European Developing Countries Clinical Trials Partnership (EDCTP).

Prevalence and Risk Factors for Betaherpesvirus DNAemia in Children >3 Weeks and <2 Years of Age Admitted to a Large Referral Hospital in Sub-Saharan Africa

BACKGROUND Betaherpesviruses are established causes of morbidity and mortality in immunosuppressed patient groups but have been little studied in sub-Saharan Africa, the epicenter of the human immunodeficiency virus (HIV) pandemic. In this region, primary infections with human cytomegalovirus (HCMV) and human herpesvirus type 6 (HHV-6) type 6 are endemic in infancy, but the clinical impact of these infections among pediatric inpatient groups is poorly characterized and assumptive, based largely on data from Western populations. METHODS We used TaqMan polymerase chain reaction to screen sera from a group of 303 pediatric inpatients aged between 3 weeks and 2 years, at the University Teaching Hospital in Lusaka, Zambia. We report the prevalence of DNAemia and viral loads within this patient group, and evaluate possible clinical associations/risk factors for betaherpesvirus infections in these hospitalized children. RESULTS We detected betaherpesvirus DNAemia in 59.1% (179/303) of children. HCMV was the most prevalent (41.3%), followed by HHV-6B (20.5%), HHV-7 (20.1%), and HHV-6A (0.3%). HIV infection (odds ratio [OR], 2.31; 95% confidence interval [CI], 1.37-3.90; P = .002), being underweight (OR, 1.82; 95% CI, 1.06-3.12; P = .03), and an admission diagnosis of suspected meningitis (OR, 5.72; 95% CI, 1.07-30.5; P = .041) were independently associated with an increased odds of HCMV DNAemia. Conversely, HHV-6B and HHV-7 DNAemia were not associated with HIV, underweight, or admission diagnosis. Median HCMV viral load was moderately but significantly higher in HIV-infected children. CONCLUSIONS Highly prevalent HCMV DNAemia was independently associated with HIV infection and being underweight across all age groups, and was also associated with meningitis, with previously underappreciated implications for the health and development of African children.

Use of the Xpert ® MTB/RIF assay for diagnosing pulmonary tuberculosis comorbidity and multidrug-resistant TB in obstetrics and gynaecology inpatient wards at the University Teaching Hospital, Lusaka, Zambia

In high‐tuberculosis (TB)‐endemic countries, comorbidity of pulmonary TB in hospitalised patients with non‐communicable diseases is well documented. In this study, we evaluated the use of the Xpert® MTB/RIF assay for the detection of concomitant pulmonary TB in patients admitted to the University Teaching Hospital, Lusaka, Zambia, with a primary obstetric or gynaecological condition.

Etiology, Antibiotic Resistance and Risk Factors for Neonatal Sepsis in a Large Referral Center in Zambia.

Background: In sub-Saharan Africa, there is scanty data on the causes of neonatal sepsis and antimicrobial resistance among common invasive pathogens that might guide policy and practice. Methods: A cross-sectional observational prevalence and etiology study of neonates with suspected sepsis admitted to the neonatal intensive care unit, University Teaching Hospital, Lusaka, Zambia, between October 2013 and May 2014. Data from blood cultures and phenotypic antibiotic susceptibility testing were compared with multivariate analysis of risk factors for neonatal sepsis. Results: Of 313 neonates with suspected sepsis, 54% (170/313) were male; 20% (62/313) were born to HIV-positive mothers; 33% (103/313) had positive blood cultures, of which 85% (88/103) were early-onset sepsis. Klebsiella species was the most prevalent isolate, accounting for 75% (77/103) of cases, followed by coagulase-negative staphylococci [6% (7/103)], Staphylococcus aureus [6% (6/103)], Escherichia coli [5% (5/103)] and Candida species [5% (5/103)]. For Klebsiella species, antibiotic resistance ranged from 96%–99% for World Health Organization-recommended first-line therapy (gentamicin and ampicillin/penicillin) to 94%–97% for third-generation cephalosporins. The prevalence of culture-confirmed sepsis increased from 0 to 39% during the period December 2013 to March 2014, during which time mortality increased 29%–47%; 93% (14/15) of late-onset sepsis and 82% (37/45) of early-onset sepsis aged 4–7 days were admitted >2 days before the onset of symptoms. Culture results for only 25% (26/103) of cases were available before discharge or death. Maternal HIV infection was associated with a reduced risk of neonatal sepsis [odds ratio, 0.46 (0.23–0.93); P = 0.029]. Conclusions: Outbreaks of nosocomial multiantibiotic-resistant infections are an important cause of neonatal sepsis and associated mortality. Reduced risk of neonatal sepsis associated with maternal HIV infection is counterintuitive and requires further investigation.

Performance of the Xpert MTB/RIF assay in the diagnosis of tuberculosis in formalin-fixed, paraffin-embedded tissues

Objective/Background: Extrapulmonary tuberculosis (EPTB), which accounts for 10%–40% of the global burden of TB, with the highest incidence in Sub-Saharan Africa, is strongly associated with human immunodeficiency virus infection. Diagnosing EPTB is challenging, and recently, there has been a concerted effort to evaluate the latest molecular diagnostics for diagnosing TB in a range of specimen types. The Xpert MTB/RIF assay (Cepheid, Sunnyvale, CA, USA) is one such technology, which simultaneously detects Mycobacterium tuberculosis and rifampicin resistance. Our objective was to evaluate the accuracy of the Xpert MTB/RIF assay for the diagnosis of EPTB and detection of rifampicin resistance in routinely processed formalin-fixed, paraffin-embedded (FFPE) tissues, compared with histological detection of TB as the gold standard. Methods: A convenience set of 100 biobanked FFPE tissues, including lymph nodes (n = 64), male genital tract tissue (n = 10), abdominal tissue (n = 8), female genital tissue (n = 5), breast tissue (n = 5), synovial tissue (n = 4), skin (n = 2), tongue tissue (n = 1), and thyroid (n = 1), from routine cases of clinically suspected EPTB admitted to the University Teaching Hospital, Lusaka, Zambia, were analyzed using the Xpert MTB/RIF assay and in-house polymerase chain reaction (PCR) assay targeting IS6110, in parallel with Ziehl–Neelsen (ZN) staining, against histology as the gold standard. Results: Some 66% of specimens had histological evidence of TB infection. ZN staining was positive for TB in 8% of cases, and Xpert MTB/RIF was positive for TB in 25% of cases. Taking histology as the gold standard, the sensitivity and specificity were as follows: In lymph tissue the accuracy of the Xpert MTB/RIF assay was 41% (95%CI 27-57), not significantly better than ZN or the in-house PCR assay. In non-lymph tissue the sensitivity of the in-house PCR assay was 82% (95%CI: 56%-95%), significantly higher than the Xpert MTB/RIF assay (P = 0.004). The Xpert MTB/RIF assay indicated rifampicin resistance in just three cases. Conclusion: The Xpert MTB/RIF assay is potentially a useful tool for the diagnosis of TB in routine FFPE tissues.

Congenital cytomegalovirus infections in sub-Saharan Africa - a neglected and growing problem

Cytomegalovirus (CMV) infection is ubiquitous and is one of the most common viral infections of humans. It belongs to the ‘herpes’ family of viruses and encodes over 160 proteins, many of which have immunomodulatory functions. CMV infection can be acquired at any age, and most initial infections go unnoticed, although some individuals develop ‘glandular fever’-like symptoms, which usually resolve (Mocarski et al. 2007). Like all herpesvirus infections, once a person acquires primary infection, CMV remains in a latent viable form within the body from which it may periodically reactivate under circumstances of immunosuppression. CMV causes two well-established serious clinical problems that are of major public health importance worldwide: (i) congenital CMV infections due to primary maternal CMV infection subsequently transmitted in utero or through breast milk or saliva up to 3 weeks post-partum and (ii) multisystem disease in immunosuppressed patients (Mocarski et al. 2007).