Browsing by Author "Whitelaw, Andrew"

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    Antibiotic stewardship ward rounds and a dedicated prescription chart reduce antibiotic consumption and pharmacy costs without affecting inpatient mortality or re-admission rates
    (Public Library of Science, 2013) Boyles, Tom H; Whitelaw, Andrew; Bamford, Colleen; Moodley, Mischka; Bonorchis, Kim; Morris, Vida; Rawoot, Naazneen; Naicker, Vanishree; Lusakiewicz, Irena; Black, John
    BACKGROUND: Antibiotic consumption is a major driver of bacterial resistance. To address the increasing burden of multi-drug resistant bacterial infections, antibiotic stewardship programmes are promoted worldwide to rationalize antibiotic prescribing and conserve remaining antibiotics. Few studies have been reported from developing countries and none from Africa that report on an intervention based approach with outcomes that include morbidity and mortality. METHODS: An antibiotic prescription chart and weekly antibiotic stewardship ward round was introduced into two medical wards of an academic teaching hospital in South Africa between January-December 2012. Electronic pharmacy records were used to collect the volume and cost of antibiotics used, the patient database was analysed to determine inpatient mortality and 30-day re-admission rates, and laboratory records to determine use of infection-related tests. Outcomes were compared to a control period, January-December 2011. RESULTS: During the intervention period, 475.8 defined daily doses were prescribed per 1000 inpatient days compared to 592.0 defined daily doses/1000 inpatient days during the control period. This represents a 19.6% decrease in volume with a cost reduction of 35% of the pharmacy's antibiotic budget. There was a concomitant increase in laboratory tests driven by requests for procalcitonin. There was no difference in inpatient mortality or 30-day readmission rate during the control and intervention periods. CONCLUSIONS: Introduction of antibiotic stewardship ward rounds and a dedicated prescription chart in a developing country setting can achieve reduction in antibiotic consumption without harm to patients. Increased laboratory costs should be anticipated when introducing an antibiotic stewardship program.
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    Bacterial disease and antimicrobial susceptibility patterns in HIV-infected, hospitalized children: a retrospective cohort study
    (Public Library of Science, 2008) Jaspan, Heather B; Huang, Lyen C; Cotton, Mark F; Whitelaw, Andrew; Myer, Landon
    BACKGROUND: Serious bacterial infections are a major source of morbidity and mortality in HIV-infected children. The spectrum of disease is wide, and responsible organisms vary according to setting. The use of antibiotic prophylaxis and the emergence of multi-drug resistant bacteria necessitate examination of responsible organisms and their antibiotic susceptibility. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective cohort study of all HIV-positive pediatric admissions at an urban public sector hospital in Cape Town between January 2002 and June 2006 was conducted. Children between the ages of one month and nine years with laboratory confirmed HIV status, serious bacterial infection, and a hospital length of stay of 5 days or more, were eligible for inclusion. Organisms isolated from blood, urine, and cerebral spinal fluid cultures and their antimicrobial susceptibility were examined, and compared according to timing of isolation to distinguish nosocomial versus community-acquired. One hundred and forty-one children were identified (median age 1.2 years), 39% of whom were on antiretrovirals started before or during this hospitalization. Bacterial infections involved all organ systems, however pneumonia was most common (67%). S. pneumoniae and S. aureus were the most common gram positive and K. pneumoniae was the most common gram negative organism. K pneumoniae isolates were resistant to many first and second line antibiotics, and were all considered nosocomial. All S. aureus isolates were methicillin resistant, some of which were community-acquired. Conclusions/Significance Bacterial infections are an important source of co-morbidity in HIV-infected children in resource-limited settings. Clinicians should have a low threshold to initiate antibiotics in children requiring hospitalization. Broad-spectrum antibiotics should be used judiciously. Clinicians caring for HIV-infected children should be cognizant of the most common organisms affecting such children, and of their local antimicrobial susceptibilities, when treating empirically for serious bacterial infections.
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    Comparison of quantitative techniques including Xpert MTB/RIF to evaluate mycobacterial burden
    (Public Library of Science, 2011) van Zyl-Smit, Richard N; Binder, Anke; Meldau, Richard; Mishra, Hridesh; Semple, Patricia L; Theron, Grant; Peter, Jonathan; Whitelaw, Andrew; Sharma, Suren K; Warren, Robin; Bateman, Eric D; Dheda, Keertan
    Introduction: Accurate quantification of mycobacterial load is important for the evaluation of patient infectiousness, disease severity and monitoring treatment response in human and in-vitro laboratory models of disease. We hypothesized that newer techniques would perform as well as solid media culture to quantify mycobacterial burden in laboratory specimens. METHODS: We compared the turn-around-time, detection-threshold, dynamic range, reproducibility, relative discriminative ability, of 4 mycobacterial load determination techniques: automated liquid culture (BACTEC-MGIT-960), [ 3 H]-uracil incorporation assays, luciferase-reporter construct bioluminescence, and quantitative PCR(Xpert -MTB/RIF) using serial dilutions of Mycobacterium bovis and Mycobacterium tuberculosis H37RV. Mycobacterial colony-forming-units(CFU) using 7H10-Middlebrook solid media served as the reference standard. RESULTS: All 4 assays correlated well with the reference standard, however, bioluminescence and uracil assays had a detection threshold ≥1×10 3 organisms. By contrast, BACTEC-MGIT-960 liquid culture, although only providing results in days, was user-friendly, had the lowest detection threshold (<10 organisms), the greatest discriminative ability (1 vs. 10 organisms; p = 0.02), and the best reproducibility (coefficient of variance of 2% vs. 38% compared to uracil incorporation; p = 0.02). Xpert-MTB/RIF correlated well with mycobacterial load, had a rapid turn-around-time (<2 hours), was user friendly, but had a detection limit of ∼100 organisms. CONCLUSIONS: Choosing a technique to quantify mycobacterial burden for laboratory or clinical research depends on availability of resources and the question being addressed. Automated liquid culture has good discriminative ability and low detection threshold but results are only obtained in days. Xpert MTB/RIF provides rapid quantification of mycobacterial burden, but has a poorer discrimination and detection threshold.
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    Culture-confirmed childhood tuberculosis in Cape Town, South Africa: a review of 596 cases
    (Biomed Central Ltd, 2007) Schaaf, H Simon; Marais, Ben; Whitelaw, Andrew; Hesseling, Anneke; Eley, Brian; Hussey, Gregory; Donald, Peter
    BACKGROUND:The clinical, radiological and microbiological features of culture-confirmed childhood tuberculosis diagnosed at two referral hospitals are described. METHODS: Cultures of Mycobacterium tuberculosis from children less than 13 years of age at Tygerberg and Red Cross Children's Hospitals, Cape Town, South Africa, were collected from March 2003 through February 2005. Folder review and chest radiography were performed and drug susceptibility tests done. RESULTS: Of 596 children (median age 31 months), 330 (55.4%) were males. Of all children, 281 (47.1%) were HIV-uninfected, 133 (22.3%) HIV-infected and 182 (30.5%) not tested. Contact with infectious tuberculosis adults was recorded in 295 (49.5%) children. Missed opportunities for chemoprophylaxis were present in 117/182 (64.3%) children less than 5 years of age.Extrathoracic TB was less common in HIV-infected than in HIV-uninfected children (49/133 vs. 156/281; odds ratio 0.50, 95% confidence interval 0.32-0.78). Alveolar opacification (84/126 vs. 128/274; OR 1.85, 95%CI 1.08-3.19) and cavitation (33/126 vs. 44/274; OR 2.28, 95%CI 1.44-3.63) were more common in HIV-infected than in HIV-uninfected children. Microscopy for acid-fast bacilli on gastric aspirates and sputum was positive in 29/142 (20.4%) and 40/125 (32.0%) children, respectively. Sixty-seven of 592 (11.3%) children's isolates showed resistance to isoniazid and/or rifampicin; 43 (7.3%) were isoniazid-monoresistant, 2 (0.3%) rifampicin-monoresistant and 22 (3.7%) multidrug-resistant. Death in 41 children (6.9%) was more common in HIV-infected children and very young infants. CONCLUSION: HIV infection and missed opportunities for chemoprophylaxis were common in children with culture-confirmed TB. With cavitating disease and sputum or gastric aspirates positive for acid-fast bacilli, children may be infectious. Transmission of drug-resistant TB is high in this setting.
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    Epidemiology of Staphylococcus aureus bacteraemia at a tertiary children's hospital in Cape Town, South Africa
    (Public Library of Science, 2013) Naidoo, Reené; Nuttall, James; Whitelaw, Andrew; Eley, Brian
    BACKGROUND: Staphylococcus aureus is an important pathogen in paediatric patients with bloodstream infections. The epidemiology of S. aureus bacteraemia, however, has not been well documented in children in South Africa. METHODS: A retrospective study was conducted at a children's hospital in Cape Town, South Africa, to investigate the epidemiology of S. aureus bacteraemia from 2007-2011. The incidence, clinical presentation, risk factors, management and outcomes of methicillin sensitive S. aureus (MSSA) and methicillin resistant S. aureus (MRSA) bacteraemia were compared. RESULTS: Over the five year study period, 365 episodes of S. aureus bacteraemia were identified. The annual incidence was 3.28 cases per 1000 hospital admissions. MRSA was responsible for 26% of S. aureus bacteraemia and 72% of nosocomial infections. Only six possible cases of community-acquired MRSA infections were described. MSSA bacteraemia was more likely to present as pulmonary and bone or joint infections, while bacteraemia without a source was the most common presentation with MRSA.  Infants, children with malnutrition, and residents of long-term care facilities were at highest risk for MRSA bacteraemia. The overall case fatality rate for S. aureus bacteraemia was 8.8% over five years, with MRSA being the only significant risk factor for mortality. CONCLUSION: The incidence of S. aureus bacteraemia and MRSA bacteraemia in children has remained stable over the past five years. MRSA is a predominantly nosocomial pathogen in children with S. aureus bacteraemia in Cape Town, South Africa.
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    Genetic basis of rifampicin resistance in methicillin-resistant Staphylococcus aureus suggests clonal expansion in hospitals in Cape Town, South Africa
    (BioMed Central Ltd, 2012) Jansen van Rensburg, Melissa; Whitelaw, Andrew; Elisha, Brenda
    BACKGROUND: Since 2001, several studies have reported high rifampicin resistance rates (45 - 100%) among methicillin-resistant Staphylococcus aureus (MRSA) isolates from South Africa. The authors previously characterised 100 MRSA isolates from hospitals in Cape Town, South Africa; forty-five percent of these isolates were rifampicin-resistant. The majority (44/45) corresponded to ST612-MRSA-IV, which is prevalent in South Africa, but has not been reported frequently elsewhere. The remaining rifampicin-resistant isolate corresponded to ST5-MRSA-I. The aim of this study was to investigate further the prevalence and genetic basis of rifampicin-resistance in MRSA isolates from hospitals in Cape Town. RESULTS: Between July 2007 and June 2011, the prevalence of rifampicin-resistant MRSA in hospitals in Cape Town ranged from 39.7% to 46.4%. Based on the results of the aforementioned study, nine ST612-MRSA-IV isolates, the rifampicin-resistant ST5-MRSA-I isolate, and two rifampicin-susceptible MRSA isolates were investigated. Four previously described ST612-MRSA-IV isolates, including two each from South Africa and Australia, were also included.The ST5-MRSA-I isolate carried a single mutational change, H481Y, commonly associated with high-level rifampicin resistance. All ST612-MRSA-IV isolates carried an uncommon double amino acid substitution in RpoB, H481N, I527M, whilst one of the Australian ST612-MRSA-IV isolates carried an additional mutation within rpoB, representing a novel rpoB genotype: H481N, I527M, K579R. All ST612-MRSA-IV isolates also shared a unique silent single nucleotide polymorphism (SNP) within rpoB. CONCLUSIONS: That local ST612-MRSA-IV isolates described here share an uncommon rpoB genotype and a unique silent SNP suggests this clone may have undergone clonal expansion in hospitals in Cape Town. Further, the data suggest that these isolates may be related to rifampicin-resistant ST612-MRSA-IV previously described in South Africa and Australia.
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    High incidence of antimicrobial resistant organisms including extended spectrum beta-lactamase producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus in nasopharyngeal and blood isolates of HIV-infected children from Cape Town, South Africa
    (BioMed Central Ltd, 2008) Cotton, Mark; Wasserman, Elizabeth; Smit, Juanita; Whitelaw, Andrew; Zar, Heather
    BACKGROUND:There is little information on nasopharyngeal (NP) flora or bacteremia in HIV-infected children. Our aim was to describe the organisms and antimicrobial resistance patterns in children enrolled in a prospective study comparing daily and three times weekly trimethoprim-sulfamethoxazole (TMP-SMX) and isoniazid (INH) or placebo prophylaxis. METHODS: NP swabs were taken at baseline from HIV-infected children enrolled in the study. Standard microbiological techniques were used. Children were grouped according to previous or current exposure to TMP-SMX and whether enrolled to the study during a period of hospitalization. Blood culture results were also recorded within 12 months of baseline. RESULTS: Two hundred and three children, median age 1.8 (Interquartile [IQ]: 0.7-4) years had NP swabs submitted for culture. One hundred and eighty-four (90.7%) had either stage B or C HIV disease. One hundred and forty-one (69.8%) were receiving TMP-SMX and 19 (9.4%) were on antiretroviral therapy. The majority, 168 (82%) had a history of hospitalization and 91 (44.8%) were enrolled during a period of hospitalization. Thirty-two subjects (16.2%) died within 12 months of study entry.One hundred and eighty-one potential pathogens were found in 167 children. The most commonly isolated organisms were Streptococcus pneumoniae (48: 22.2%), Gram-negative respiratory organisms (Haemophilus influenzae and Moraxella catarrhalis) (47: 21.8%), Staphylococcus aureus (44: 20.4%), Enterobacteriaceae 32 (14.8%) and Pseudomonas 5 (2.3%).Resistance to TMP-SMX occurred in > 80% of pathogens except for M. catarrhalis (2: 18.2% of tested organisms). TMP-SMX resistance tended to be higher in those receiving it at baseline (p = 0.065). Carriage of Methicillin resistant S. aureus (MRSA) was significantly associated with being on TMP-SMX at baseline (p = 0.002). Minimal inhibitory concentrations (MIC) to penicillin were determined for 18 S. pneumoniae isolates: 7 (38.9%) were fully sensitive (MIC [less than or equal to] 0.06 mug/ml), 9 (50%) had intermediate resistance (MIC 0.12 - 1 mug/ml) and 2 (11.1%) had high level resistance (MIC [greater than or equal to]2 mug/ml). Fifty percent of Enterobacteriaceae produced extended spectrum beta-lactamases (ESBL) (resistant to third generation cephalosporins) and 56% were resistant to gentamicin. Seventy-seven percent of S. aureus were MRSA. Carriage of resistant organisms was not associated with hospitalization.On multivariate logistic regression, risk factors for colonization with Enterobacteriaceae were age [less than or equal to] one year (Odds ratio 4.4; 95% Confidence Interval 1.9-10.9; p = 0.0008) and CDC stage C disease (Odds ratio 3.6; 95% Confidence Interval 1.5-8.6; p = 0.005)Nineteen (9.4%) subjects had 23 episodes of bacteremia. Enterobacteriaceae were most commonly isolated (13 of 25 isolates), of which 6 (46%) produced ESBL and were resistant to gentamicin. CONCLUSION: HIV-infected children are colonized with potential pathogens, most of which are resistant to commonly used antibiotics. TMP-SMX resistance is extremely common. Antibiotic resistance is widespread in colonizing organisms and those causing invasive disease. Antibiotic recommendations should take cognizance of resistance patterns. Antibiotics appropriate for ESBL-producing Enterobacteriaceae and MRSA should be used for severely ill HIV-infected children in our region. Further study of antibiotic resistance patterns in HIV-infected children from other areas is needed.
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    ICU-Associated Acinetobacter baumannii Colonisation/Infection in a High HIV-Prevalence Resource-Poor Setting
    (Public Library of Science, 2012) Ntusi, Ntobeko B A; Badri, Motasim; Khalfey, Hoosain; Whitelaw, Andrew; Oliver, Stephen; Piercy, Jenna; Raine, Richard; Joubert, Ivan; Dheda, Keertan
    BACKGROUND: There are hardly any data about the incidence, risk factors and outcomes of ICU-associated A.baumannii colonisation/infection in HIV-infected and uninfected persons from resource-poor settings like Africa. METHODS: We reviewed the case records of patients with A.baumannii colonisation/infection admitted into the adult respiratory and surgical ICUs in Cape Town, South Africa, from January 1 to December 31 2008. In contrast to colonisation, infection was defined as isolation of A.baumannii from any biological site in conjunction with a compatible clinical picture warranting treatment with antibiotics effective against A.baumannii . RESULTS: The incidence of A.baumannii colonisation/infection in 268 patients was 15 per 100 person-years, with an in-ICU mortality of 26.5 per 100 person-years. The average length of stay in ICU was 15 days (range 1-150). A.baumannii was most commonly isolated from the respiratory tract followed by the bloodstream. Independent predictors of mortality included older age (p = 0.02), low CD4 count if HIV-infected (p = 0.038), surgical intervention (p = 0.047), co-morbid Gram-negative sepsis (p = 0.01), high APACHE-II score (p = 0.001), multi-organ dysfunction syndrome (p = 0.012), and a positive blood culture for A.baumannii (p = 0.017). Of 21 A.baumannii colonised/infected HIV-positive persons those with clinical AIDS (CD4<200 cells/mm 3 ) had significantly higher in-ICU mortality and were more likely to have a positive blood culture. Conclusion In this resource-poor setting A.baumannii infection in critically ill patients is common and associated with high mortality. HIV co-infected patients with advanced immunosuppression are at higher risk of death.
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    Impact of Xpert MTB/RIF for TB diagnosis in a primary care clinic with high TB and HIV prevalence in South Africa: a pragmatic randomised trial
    (Public Library of Science, 2014) Cox, Helen S; Mbhele, Slindile; Mohess, Neisha; Whitelaw, Andrew; Muller, Odelia; Zemanay, Widaad; Little, Francesca; Azevedo, Virginia; Simpson, John; Boehme, Catharina C; Nicol, Mark P
    Background: Xpert MTB/RIF is approved for use in tuberculosis (TB) and rifampicin-resistance diagnosis. However, data are limited on the impact of Xpert under routine conditions in settings with high TB burden. Methods and Findings: A pragmatic prospective cluster-randomised trial of Xpert for all individuals with presumptive (symptomatic) TB compared to the routine diagnostic algorithm of sputum microscopy and limited use of culture was conducted in a large TB/HIV primary care clinic. The primary outcome was the proportion of bacteriologically confirmed TB cases not initiating TB treatment by 3 mo after presentation. Secondary outcomes included time to TB treatment and mortality. Unblinded randomisation occurred on a weekly basis. Xpert and smear microscopy were performed on site. Analysis was both by intention to treat (ITT) and per protocol. Between 7 September 2010 and 28 October 2011, 1,985 participants were assigned to the Xpert (n = 982) and routine (n = 1,003) diagnostic algorithms (ITT analysis); 882 received Xpert and 1,063 routine (per protocol analysis). 13% (32/257) of individuals with bacteriologically confirmed TB (smear, culture, or Xpert) did not initiate treatment by 3 mo after presentation in the Xpert arm, compared to 25% (41/167) in the routine arm (ITT analysis, risk ratio 0.51, 95% CI 0.33–0.77, p = 0.0052). The yield of bacteriologically confirmed TB cases among patients with presumptive TB was 17% (167/1,003) with routine diagnosis and 26% (257/982) with Xpert diagnosis (ITT analysis, risk ratio 1.57, 95% CI 1.32–1.87, p<0.001). This difference in diagnosis rates resulted in a higher rate of treatment initiation in the Xpert arm: 23% (229/1,003) and 28% (277/982) in the routine and Xpert arms, respectively (ITT analysis, risk ratio 1.24, 95% CI 1.06–1.44, p = 0.013). Time to treatment initiation was improved overall (ITT analysis, hazard ratio 0.76, 95% CI 0.63–0.92, p = 0.005) and among HIV-infected participants (ITT analysis, hazard ratio 0.67, 95% CI 0.53–0.85, p = 0.001). There was no difference in 6-mo mortality with Xpert versus routine diagnosis. Study limitations included incorrect intervention allocation for a high proportion of participants and that the study was conducted in a single clinic. Conclusions: These data suggest that in this routine primary care setting, use of Xpert to diagnose TB increased the number of individuals with bacteriologically confirmed TB who were treated by 3 mo and reduced time to treatment initiation, particularly among HIV-infected participants.
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    Improved detection of Pneumocystis jirovecii in upper and lower respiratory tract specimens from children with suspected pneumocystis pneumonia using real-time PCR: a prospective study
    (BioMed Central Ltd, 2011) Samuel, Catherine M; Whitelaw, Andrew; Corcoran, Craig; Morrow, Brenda; Hsiao, Nei-Yuan; Zampoli, Marco; Zar, Heather
    BACKGROUND: Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in HIV-infected African children. Microbiologic diagnosis relies predominantly on silver or immunofluorescent staining of a lower respiratory tract (LRT) specimens which are difficult to obtain in children. Diagnosis on upper respiratory tract (URT) specimens using PCR has been reported useful in adults, but data in children are limited. The main objectives of the study was (1) to compare the diagnostic yield of PCR with immunofluorescence (IF) and (2) to investigate the usefulness of upper compared to lower respiratory tract samples for diagnosing PCP in children. METHODS: Children hospitalised at an academic hospital with suspected PCP were prospectively enrolled. An upper respiratory sample (nasopharyngeal aspirate, NPA) and a lower respiratory sample (induced sputum, IS or bronchoalveolar lavage, BAL) were submitted for real-time PCR and direct IF for the detection of Pneumocystis jirovecii. A control group of children with viral lower respiratory tract infections were investigated with PCR for PCP. RESULTS: 202 children (median age 3.3 [inter-quartile range, IQR 2.2 - 4.6] months) were enrolled. The overall detection rate by PCR was higher than by IF [180/349 (52%) vs. 26/349 (7%) respectively; p < 0.0001]. PCR detected more infections compared to IF in lower respiratory tract samples [93/166 (56%) vs. 22/166 (13%); p < 0.0001] and in NPAs [87/183 (48%) vs. 4/183 (2%); p < 0.0001]. Detection rates by PCR on upper (87/183; 48%) compared with lower respiratory tract samples (93/166; 56%) were similar (OR, 0.71; 95% CI, 0.46 - 1.11). Only 2/30 (6.6%) controls were PCR positive. CONCLUSION: Real-time PCR is more sensitive than IF for the detection of P. jirovecii in children with PCP. NPA samples may be used for diagnostic purposes when PCR is utilised. Wider implementation of PCR on NPA samples is warranted for diagnosing PCP in children.
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    Isolation of Non-Tuberculous Mycobacteria in Children Investigated for Pulmonary Tuberculosis
    (Public Library of Science, 2006) Hatherill, Mark; Hawkridge, Tony; Whitelaw, Andrew; Tameris, Michele; Mahomed, Hassan; Moyo, Sizulu; Hanekom, Willem; Hussey, Gregory
    Objective To evaluate the frequency and clinical significance of non-tuberculous mycobacteria (NTM) isolates among children investigated for pulmonary tuberculosis in a rural South African community. METHODS: Children were investigated for pulmonary tuberculosis as part of a tuberculosis vaccine surveillance program (2001-2005). The clinical features of children in whom NTM were isolated, from induced sputum or gastric lavage, were compared to those with culture-proven M. tuberculosis . RESULTS: Mycobacterial culture demonstrated 114 NTM isolates from 109 of the 1,732 children investigated, a crude yield of 6% (95% CI 5-7). The comparative yield of positive NTM cultures from gastric lavage was 40% (95% CI 31-50), compared to 67% (95% CI 58-76) from induced sputum. 95% of children with NTM isolates were symptomatic. Two children were HIV-infected. By contrast, M. tuberculosis was isolated in 187 children, a crude yield of 11% (95% CI 9-12). Compared to those with culture-proven M. tuberculosis , children with NTM isolates were less likely to demonstrate acid-fast bacilli on direct smear microscopy (OR 0.19; 95% 0.0-0.76). Children with NTM were older (p<0.0001), and more likely to demonstrate constitutional symptoms (p = 0.001), including fever (p = 0.003) and loss of weight or failure to gain weight (p = 0.04), but less likely to demonstrate a strongly positive tuberculin skin test (p<0.0001) or radiological features consistent with pulmonary tuberculosis (p = 0.04). DISCUSSION: NTM were isolated in 6% of all children investigated for pulmonary tuberculosis and in more than one third of those with a positive mycobacterial culture. NTM may complicate the diagnosis of PTB in regions that lack capacity for mycobacterial species identification. The association of NTM isolates with constitutional symptoms suggestive of host recognition requires further investigation.
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    Leaving the party - withdrawal of South African essential medicines
    (2005) Wilmshurst, Jo M; Blockman, Marc; Argent, Andrew; Gordon-Graham, Eugenie; Thomas, Jenny; Whitelaw, Andrew; McCulloch, Mignon; Ramiah, Malitha; Dyeshana, H; Ireland, Joe
    In August 2004 pharmacies and drug depots were advised that the sole supplier of parenteral phenobarbitone in South Africa, essential for the management of status epilepticus in children, was stopping production at the end of the same year. Alternative protocols for the management of status epilepticus resulted in more children requiring intensive care intervention (N = 9) at the Red Cross Children’s Hospital, over a 2-month period, than had occurred in any 12-month period since 2000 (2000 N = 3, 2001 N = 1, 2002 N = 1, 2003 N = 2, 2004 N = 7). Other agents that have suffered or are at risk of the same fate are sodium nitroprusside, labetalol and esmolol. Sodium nitroprusside is used extensively in the peri-operative period in cardiac patients requiring after-load reduction. There are no other nitrates with equivalent efficacy. Supply was stopped in 2005 and only reinstated after the pharmaceutical company was contacted directly. Supply of labetalol and esmolol was stopped without warning. Without access to these products it is necessary to resort to agents that are not appropriate for paediatric use. Acetylcysteine (Parvolex), used in the management of acetaminophen overdose, also became unavailable and the supply was re-established only after direct communication with the pharmaceutical company.
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    The molecular diagnosis of Pneumocystis pneumonia in children using nasopharyngeal aspirate samples
    (2011) Samuel, Catherine Mary; Whitelaw, Andrew; Corcoran, Craig
    Pneumocystis pneumonia (PCP) is an important opportunistic infection caused by thefungus Pneumocystis jirovecii. The incidence of PCP in sub-Saharan Africa is on theincrease. This is due to the progression of the HIV-pandemic and limited access to healthcare facilities, specific highly active anti-retroviral therapy and chemoprophylaxis. It is a major cause of hospitalization and mortality in HIV-infected children with in-hospital case-fatality rates ranging from 20-63%.
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    Pneumocystis pneumonia in South African children diagnosed by molecular methods
    (BioMed Central, 2014-01-10) Morrow, Brenda M; Samuel, Catherine M; Zampoli, Marco; Whitelaw, Andrew; Zar, Heather J
    Background: Pneumocystis pneumonia (PCP) is an important cause of hospitalization and mortality in HIV-infected children. However, the incidence of PCP has been underestimated due to poor sensitivity of diagnostic tests. The use of polymerase chain reaction (PCR) for pneumocystis has enabled more reliable diagnosis. This study describes the incidence, clinical features and outcome of PCP in South African children diagnosed using PCR. Methods: A prospective study of children hospitalised in South Africa with suspected PCP was done from November 2006 to August 2008. Clinical, laboratory and radiological information were collected. Lower respiratory tract specimens were obtained for PCP immunofluorescence (IF), real- time PCR for pneumocystis, bacterial and mycobacterial culture. Nasopharyngeal aspirates were taken for immunofluorescence (IF), real-time PCR for pneumocystis and PCR for respiratory viruses. A blood specimen for bacterial culture and for cytomegalovirus PCR was taken. Children were followed for the duration of their hospitalisation and the outcome was recorded. Results: 202 children [median (interquartile range, IQR) age 3.2 (2.1– 4.6) months] were enrolled; 124 (61.4%) were HIV infected. PCP was identified in 109 (54%) children using PCR, compared to 43 (21%) using IF and Grocott staining (p < 0.0001). Most PCP cases (88, 81%) occurred in HIV-infected children. All 21 cases (19%) occurring in HIV- negative children had another risk factor for PCP. On logistic regression, predictive factors for PCP were HIV infection, lack of fever, high respiratory rate and low oxygen saturation whilst cotrimoxazole prophylaxis was protective (OR 0.24; 95% CI 0.1 to 0.5; p < 0.002). The case fatality of children with PCP was higher than those without PCP (32.1% versus 17.2%; relative risk 1.87; 95% confidence interval (CI) 1.11 – 3.15). Amongst HIV-infected children, a CD4 less than 15% was the only independent predictor of mortality. Conclusions: The diagnostic yield for PCP is more than 2.5 times higher on PCR than other detection methods. PCP is a very common cause of severe hypoxic pneumonia and is associated with high mortality in HIV-infected African infants.
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    Rapid diagnosis of tuberculosis with the Xpert MTB/RIF assay in high burden countries: a cost-effectiveness analysis
    (Public Library of Science, 2011) Vassall, Anna; van Kampen, Sanne; Sohn, Hojoon; Michael, Joy S; John, K R; den Boon, Saskia; Davis, J Lucian; Whitelaw, Andrew; Nicol, Mark P; Gler, Maria Tarcela; Khaliqov, Anar; Zamudio, Carlos; Perkins, Mark D; Boehme, Catharina C; Cobelens, Frank
    Background: Xpert MTB/RIF (Xpert) is a promising new rapid diagnostic technology for tuberculosis (TB) that has characteristics that suggest large-scale roll-out. However, because the test is expensive, there are concerns among TB program managers and policy makers regarding its affordability for low- and middle-income settings. Methods and Findings: We estimate the impact of the introduction of Xpert on the costs and cost-effectiveness of TB care using decision analytic modelling, comparing the introduction of Xpert to a base case of smear microscopy and clinical diagnosis in India, South Africa, and Uganda. The introduction of Xpert increases TB case finding in all three settings; from 72%–85% to 95%–99% of the cohort of individuals with suspected TB, compared to the base case. Diagnostic costs (including the costs of testing all individuals with suspected TB) also increase: from US$28–US$49 to US$133–US$146 and US$137–US$151 per TB case detected when Xpert is used "in addition to" and "as a replacement of" smear microscopy, respectively. The incremental cost effectiveness ratios (ICERs) for using Xpert "in addition to" smear microscopy, compared to the base case, range from US$41–$110 per disability adjusted life year (DALY) averted. Likewise the ICERS for using Xpert "as a replacement of" smear microscopy range from US$52–$138 per DALY averted. These ICERs are below the World Health Organization (WHO) willingness to pay threshold. Conclusions: Our results suggest that Xpert is a cost-effective method of TB diagnosis, compared to a base case of smear microscopy and clinical diagnosis of smear-negative TB in low- and middle-income settings where, with its ability to substantially increase case finding, it has important potential for improving TB diagnosis and control. The extent of cost-effectiveness gain to TB programmes from deploying Xpert is primarily dependent on current TB diagnostic practices. Further work is required during scale-up to validate these findings.
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    Screening for HIV-associated tuberculosis and rifampicin resistance before antiretroviral therapy using the Xpert MTB/RIF assay: a prospective study
    (Public Library of Science, 2011) Lawn, Stephen D; Brooks, Sophie V; Kranzer, Katharina; Nicol, Mark P; Whitelaw, Andrew; Vogt, Monica; Bekker, Linda-Gail; Wood, Robin
    Background: The World Health Organization has endorsed the Xpert MTB/RIF assay for investigation of patients suspected of having tuberculosis (TB). However, its utility for routine TB screening and detection of rifampicin resistance among HIV-infected patients with advanced immunodeficiency enrolling in antiretroviral therapy (ART) services is unknown. Methods and Findings: Consecutive adult HIV-infected patients with no current TB diagnosis enrolling in an ART clinic in a South African township were recruited regardless of symptoms. They were clinically characterised and invited to provide two sputum samples at a single visit. The accuracy of the Xpert MTB/RIF assay for diagnosing TB and drug resistance was assessed in comparison with other tests, including fluorescence smear microscopy and automated liquid culture (gold standard) and drug susceptibility testing. Of 515 patients enrolled, 468 patients (median CD4 cell count, 171 cells/µl; interquartile range, 102–236) produced at least one sputum sample, yielding complete sets of results from 839 samples. Mycobacterium tuberculosis was cultured from 81 patients (TB prevalence, 17.3%). The overall sensitivity of the Xpert MTB/RIF assay for culture-positive TB was 73.3% (specificity, 99.2%) compared to 28.0% (specificity, 100%) using smear microscopy. All smear-positive, culture-positive disease was detected by Xpert MTB/RIF from a single sample (sensitivity, 100%), whereas the sensitivity for smear-negative, culture-positive TB was 43.4% from one sputum sample and 62.3% from two samples. Xpert correctly identified rifampicin resistance in all four cases of multidrug-resistant TB but incorrectly identified resistance in three other patients whose disease was confirmed to be drug sensitive by gene sequencing (specificity, 94.1%; positive predictive value, 57%). Conclusions: In this population of individuals at high risk of TB, intensive screening using the Xpert MTB/RIF assay increased case detection by 45% compared with smear microscopy, strongly supporting replacement of microscopy for this indication. However, despite the ability of the assay to rapidly detect rifampicin-resistant disease, the specificity for drug-resistant TB was sub-optimal.