Keren Middelkoop

Dr. Keren Middelkoop


Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 July 2014 in The Journal of Infectious Diseases
Verified
Journal Article
Open access
PDF file
KMKeren Middelkoop
Keren Middelkoop
BMBarun Mathema
Barun Mathema
LMLandon Myer
Landon Myer
ESElena Shashkina
Elena Shashkina
AWAndrew Whitelaw
Andrew Whitelaw
LBLinda-Gail Bekker
Linda-Gail Bekker
Background. In settings of high tuberculosis transmission, little is known of the interaction between human immunodeficiency virus (HIV) positive and HIV-negative tuberculosis disease and of the impact of antiretroviral treatment (ART) programs on tuberculosis transmission dynamics. Methods. Mycobacterium tuberculosis isolates were collected from patients with tuberculosis who resided in a South African township with a high burden of tuberculosis and HIV infection. Demographic and clinical data were extracted from clinic records. Isolates underwent IS6110-based restriction fragment length polymorphism analysis. Patients with unique (nonclustered) M. tuberculosis genotypes and cluster index cases (ie, the first tuberculosis case in a cluster) were defined as having tuberculosis due to reactivation of latent M. tuberculosis infection. Secondary cases in clusters were defined as having tuberculosis due to recent M. tuberculosis infection. Results. Overall, 311 M. tuberculosis genotypes were identified among 718 isolates from 710 patients; 224 (31%) isolates were unique strains, and 478 (67%) occurred in 87 clusters. Cluster index cases were significantly more likely than other tuberculosis cases to be HIV negative. HIV-positive patients were more likely to be secondary cases (P = .001), including patients receiving ART (P = .004). Only 8% of cases of adult-adult transmission of tuberculosis occurred on shared residential plots. Conclusions. Recent infection accounted for the majority of tuberculosis cases, particularly among HIV-positive patients, including patients receiving ART. HIV-negative patients may be disproportionally responsible for ongoing transmission.

1 June 2011 in BMC Infectious Diseases
Verified
Journal Article
Open access
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KMKeren Middelkoop
Keren Middelkoop
LBLinda-Gail Bekker
Linda-Gail Bekker
HLHua Liang
Hua Liang
LALisa Dh Aquino
Lisa Dh Aquino
ESElaine Sebastian
Elaine Sebastian
RWRobin Wood
Robin Wood
Understanding of the transmission dynamics of tuberculosis (TB) in high TB and HIV prevalent settings is required in order to develop effective intervention strategies for TB control. However, there are little data assessing incidence of TB infection in adolescents in these settings.

27 February 2012 in BMC Infectious Diseases
Verified
Journal Article
Open access
PDF file
RWRobin Wood
Robin Wood
KRKimberly Racow
Kimberly Racow
LBLinda-Gail Bekker
Linda-Gail Bekker
KMKeren Middelkoop
Keren Middelkoop
MVMonica Vogt
Monica Vogt
SLStephen D Lawn
Stephen D Lawn
Background: Detection of lipoarabinomannan (LAM), a Mycobacterium tuberculosis (Mtb) cell wall antigen, is a potentially attractive diagnostic. However, the LAM-ELISA assay has demonstrated variable sensitivity in diagnosing TB in diverse clinical populations. We therefore explored pathogen and host factors potentially impacting LAM detection. Methods: LAM-ELISA assay testing, sputum smear and culture status, HIV status, CD4 cell count, proteinuria and TB outcomes were prospectively determined in adults diagnosed with TB and commencing TB treatment at a South African township TB clinic. Sputum TB isolates were characterised by IS61110-based restriction fragment length polymorphism (RFLP) and urines were tested for mycobacteriuria by Xpert® MTB/RIF assay. Results: 32/199 (16.1%) of patients tested LAM-ELISA positive. Median optical density and proportion testing LAM positive remained unchanged during 2 weeks of treatment and then declined over 24 weeks. LAM was associated with positive sputum smear and culture status, HIV infection and low CD4 cell counts but not proteinuria, RFLP strain or TB treatment outcome. The sensitivity of LAM for TB in HIV-infected patients with CD4 counts of ≥ 200, 100-199, 50-99, and < 50 cells/μl, was 15.2%, 32%, 42.9%, and 69.2% respectively. Mycobacteriuria was found in 15/32 (46.9%) of LAM positive patients and in none of the LAM negative controls. Conclusions: Urinary LAM was related to host immune factors, was unrelated to Mtb strain and declined steadily after an initial 2 weeks of TB treatment. The strong association of urine LAM with mycobacteriuria is a new finding, indicating frequent TB involvement of the renal tract in advanced HIV infection.

15 December 2017 in BMC Public Health
Verified
Journal Article
Open access
PDF file
EHEmily P. Hyle
Emily P. Hyle
BMBongani M. Mayosi
Bongani M. Mayosi
KMKeren Middelkoop
Keren Middelkoop
MMMosepele Mosepele
Mosepele Mosepele
EMEmily B. Martey
Emily B. Martey
VTVirginia A. Triant
Virginia A. Triant
Sub-Saharan Africa (SSA) has confronted decades of the HIV epidemic with substantial improvements in access to life-saving antiretroviral therapy (ART). Now, with improved survival, people living with HIV (PLWH) are at increased risk for non-communicable diseases (NCDs), including atherosclerotic cardiovascular disease (CVD). We assessed the existing literature regarding the association of CVD outcomes and HIV in SSA. We used the PRISMA guidelines to perform a systematic review of the published literature regarding the association of CVD and HIV in SSA with a focus on CVD surrogate and clinical outcomes in PLWH. From January 2000 until March 2017, 31 articles were published regarding CVD outcomes among PLWH in SSA. Data from surrogate CVD outcomes (n = 13) suggest an increased risk of CVD events among PLWH in SSA. Although acute coronary syndrome is reported infrequently in SSA among PLWH, limited data from five studies suggest extensive thrombus and hypercoagulability as contributing factors. Additional studies suggest an increased risk of stroke among PLWH (n = 13); however, most data are from immunosuppressed ART-naïve PLWH and thus are potentially confounded by the possibility of central nervous system infections. Given ongoing gaps in our current understanding of CVD and other NCDs in PLWH in SSA, it is imperative to ascertain the burden of CVD outcomes, and to examine strategies for intervention and best practices to enhance the health of this vulnerable population.

15 October 2010 in American Journal of Respiratory and Critical Care Medicine
Verified
Journal Article
Closed access
KMKeren Middelkoop
Keren Middelkoop
LBLinda-Gail Bekker
Linda-Gail Bekker
LMLandon Myer
Landon Myer
AWAndrew Whitelaw
Andrew Whitelaw
AGAlison Grant
Alison Grant
RWRobin Wood
Robin Wood
Rationale: In 2005, we reported high prevalence of untreated pulmonary tuberculosis (TB) in a South African community. Prevalent untreated TB is the main source of transmission. In settings with large burdens of human immunodeficiency virus (HIV) and TB, highly active antiretroviral therapy (HAART) may contribute to TB control. Objectives: To assess the community-level impact of HAART on TB prevalence, we repeated a community-based TB prevalence cross-sectional survey in 2008 following HAART roll-out. Methods: A random 10% adult population sample was identified from the community. Participants provided two sputum specimens for acid-fast bacilli microscopy and TB culture. Oral transudate specimen was collected for anonymous HIV testing, linked to TB diagnosis. An interviewer-administered, structured questionnaire identified TB and HIV history and risk factors. Measurements and Main Results: In the 2008 survey, 1,250 adults participated (90% response rate); 306 (25%) tested HIV positive, of which 60 (20%) were receiving HAART. A total of 20 TB cases were identified (12 receiving TB treatment), representing a significant decline in prevalence from 3.2 to 1.6% (P = 0.02) between the surveys. TB prevalence in participants not infected with HIV was unchanged (P = 0.90). The decline occurred among participants not infected with HIV, decreasing from 9.2 to 3.6% in 2005 to 2008, respectively (P = 0.003). In participants infected with HIV, prevalence of treated TB declined from 4 to 2.3% (P = 0.06), and untreated TB prevalence from 5.2 to 1.3% (P = 0.02). The proportion of untreated TB in patients receiving HAART decreased significantly, from 22 to 0% (P < 0.001). Conclusions: Prevalence of undiagnosed TB declined significantly over a period of increasing HAART availability. The decline was predominantly in individuals infected with HIV receiving HAART.

23 April 2014 in BMC Infectious Diseases
Verified
Journal Article
Open access
PDF file
KMKeren Middelkoop
Keren Middelkoop
LBLinda-Gail Bekker
Linda-Gail Bekker
CMCarl Morrow
Carl Morrow
NLNamee Lee
Namee Lee
RWRobin Wood
Robin Wood
Tuberculosis (TB) transmission rates are exceptionally high in endemic TB settings. Adolescence represents a period of increasing TB infection and disease but little is known as to where adolescents acquire TB infection. We explored the relationship between residential exposure to adult TB cases and infection in children and adolescents in a South African community with high burdens of TB and HIV.