Treatment and outcomes in children with multidrug-resistant tuberculosis: A systematic review and individual patient data meta-analysis.

BACKGROUND: An estimated 32,000 children develop multidrug-resistant tuberculosis (MDR-TB; Mycobacterium tuberculosis resistant to isoniazid and rifampin) each year. Little is known about the optimal treatment for these children. METHODS AND FINDINGS: To inform the pediatric aspects of the revised World Health Organization (WHO) MDR-TB treatment guidelines, we performed a systematic review and individual patient data (IPD) meta-analysis, describing treatment outcomes in children treated for MDR-TB. To identify eligible reports we searched PubMed, LILACS, Embase, The Cochrane Library, PsychINFO, and BioMedCentral databases through 1 October 2014. To identify unpublished data, we reviewed conference abstracts, contacted experts in the field, and requested data through other routes, including at national and international conferences and through organizations working in pediatric MDR-TB. A cohort was eligible for inclusion if it included a minimum of three children (aged <15 years) who were treated for bacteriologically confirmed or clinically diagnosed MDR-TB, and if treatment outcomes were reported. The search yielded 2,772 reports; after review, 33 studies were eligible for inclusion, with IPD provided for 28 of these. All data were from published or unpublished observational cohorts. We analyzed demographic, clinical, and treatment factors as predictors of treatment outcome. In order to obtain adjusted estimates, we used a random-effects multivariable logistic regression (random intercept and random slope, unless specified otherwise) adjusted for the following covariates: age, sex, HIV infection, malnutrition, severe extrapulmonary disease, or the presence of severe disease on chest radiograph. We analyzed data from 975 children from 18 countries; 731 (75%) had bacteriologically confirmed and 244 (25%) had clinically diagnosed MDR-TB. The median age was 7.1 years. Of 910 (93%) children with documented HIV status, 359 (39%) were infected with HIV. When compared to clinically diagnosed patients, children with confirmed MDR-TB were more likely to be older, to be infected with HIV, to be malnourished, and to have severe tuberculosis (TB) on chest radiograph (p < 0.001 for all characteristics). Overall, 764 of 975 (78%) had a successful treatment outcome at the conclusion of therapy: 548/731 (75%) of confirmed and 216/244 (89%) of clinically diagnosed children (absolute difference 14%, 95% confidence interval [CI] 8%-19%, p < 0.001). Treatment was successful in only 56% of children with bacteriologically confirmed TB who were infected with HIV who did not receive any antiretroviral treatment (ART) during MDR-TB therapy, compared to 82% in children infected with HIV who received ART during MDR-TB therapy (absolute difference 26%, 95% CI 5%-48%, p = 0.006). In children with confirmed MDR-TB, the use of second-line injectable agents and high-dose isoniazid (15-20 mg/kg/day) were associated with treatment success (adjusted odds ratio [aOR] 2.9, 95% CI 1.0-8.3, p = 0.041 and aOR 5.9, 95% CI 1.7-20.5, p = 0.007, respectively). These findings for high-dose isoniazid may have been affected by site effect, as the majority of patients came from Cape Town. Limitations of this study include the difficulty of estimating the treatment effects of individual drugs within multidrug regimens, only observational cohort studies were available for inclusion, and treatment decisions were based on the clinician's perception of illness, with resulting potential for bias. CONCLUSIONS: This study suggests that children respond favorably to MDR-TB treatment. The low success rate in children infected with HIV who did not receive ART during their MDR-TB treatment highlights the need for ART in these children. Our findings of individual drug effects on treatment outcome should be further evaluated.

Molecular characterisation of clinical and environmental isolates of Mycobacterium kansasii isolates from South African gold mines.

Mycobacterium kansasii (M. kansasii) is a major cause of non-tuberculous mycobacterial pulmonary disease in the South African gold-mining workforce, but the source of infection and molecular epidemiology are unknown. This study investigated the presence of M. kansasii in gold and coal mine and associated hostel water supplies and compared the genetic diversity of clinical and environmental isolates of M. kansasii. Five M. kansasii and ten other potentially pathogenic mycobacteria were cultured mainly from showerhead biofilms. Polymerase chain reaction-restriction analysis of the hsp65 gene on 196 clinical and environmental M. kansasii isolates revealed 160 subtype I, eight subtype II and six subtype IV strains. Twenty-two isolates did not show the typical M. kansasii restriction patterns, suggesting that these isolates may represent new subtypes of M. kansasii. In contrast to the clonal population structure found amongst the subtype I isolates from studies in other countries, DNA fingerprinting of 114 clinical and three environmental subtype I isolates demonstrated genetic diversity amongst the isolates. This study demonstrated that showerheads are possible sources of M. kansasii and other pathogenic non-tuberculous mycobacterial infection in a gold-mining region, that subtype I is the major clinical isolate of M. kansasii strain and that this subtype exhibits genetic diversity.

Epidemic spread of multidrug-resistant tuberculosis in Johannesburg, South Africa.

Numerous reports have documented isolated transmission events or clonal outbreaks of multidrug-resistant Mycobacterium tuberculosis strains, but knowledge of their epidemic spread remains limited. In this study, we evaluated drug resistance, strain diversity, and clustering rates in patients diagnosed with multidrug-resistant (MDR) tuberculosis (TB) at the National Health Laboratory Service (NHLS) Central TB Laboratory in Johannesburg, South Africa, between March 2004 and December 2007. Phenotypic drug susceptibility testing was done using the indirect proportion method, while each isolate was genotyped using a combination of spoligotyping and 12-MIRU typing (12-locus multiple interspersed repetitive unit typing). Isolates from 434 MDR-TB patients were evaluated, of which 238 (54.8%) were resistant to four first-line drugs (isoniazid, rifampin, ethambutol, and streptomycin). Spoligotyping identified 56 different strains and 28 clusters of variable size (2 to 71 cases per cluster) with a clustering rate of 87.1%. Ten clusters included 337 (77.6%) of all cases, with strains of the Beijing genotype being most prevalent (16.4%). Combined analysis of spoligotyping and 12-MIRU typing increased the discriminatory power (Hunter Gaston discriminatory index [HGDI] = 0.962) and reduced the clustering rate to 66.8%. Resolution of Beijing genotype strains was further enhanced with the 24-MIRU-VNTR (variable-number tandem repeat) typing method by identifying 15 subclusters and 19 unique strains from twelve 12-MIRU clusters. High levels of clustering among a variety of strains suggest a true epidemic spread of MDR-TB in the study setting, emphasizing the urgency of early diagnosis and effective treatment to reduce transmission within this community.

Population structure of multi- and extensively drug-resistant Mycobacterium tuberculosis strains in South Africa.

Genotyping of multidrug-resistant (MDR) Mycobacterium tuberculosis strains isolated from tuberculosis (TB) patients in four South African provinces (Western Cape, Eastern Cape, KwaZulu-Natal, and Gauteng) revealed a distinct population structure of the MDR strains in all four regions, despite the evidence of substantial human migration between these settings. In all analyzed provinces, a negative correlation between strain diversity and an increasing level of drug resistance (from MDR-TB to extensively drug-resistant TB [XDR-TB]) was observed. Strains predominating in XDR-TB in the Western and Eastern Cape and KwaZulu-Natal Provinces were strongly associated with harboring an inhA promoter mutation, potentially suggesting a role of these mutations in XDR-TB development in South Africa. Approximately 50% of XDR-TB cases detected in the Western Cape were due to strains probably originating from the Eastern Cape. This situation may illustrate how failure of efficient health care delivery in one setting can burden health clinics in other areas.

The nucleoside reverse transcriptase inhibitors didanosine, lamivudine, stavudine and zidovudine show little effect on the virulence of Candida albicans in vitro.

Nucleoside reverse transcriptase inhibitors (NRTIs) are used in the treatment of human immunodeficiency virus (HIV). Since the analogue 5-fluorouracil increases Candida albicans virulence in vitro, and zidovudine therapy is associated with enhanced C. albicans adherence and biofilm formation, we investigated the effects of commonly used NRTIs on the virulence of C. albicans isolated from 21 antiretroviral-naïve HIV/AIDS patients. The isolates were exposed to didanosine, lamivudine, stavudine and zidovudine at their expected patient serum peak levels and at one-half and two times these levels for 24h and 72 h. Assays assessing changes in adherence, proliferation, biofilm formation and antifungal susceptibility were performed. No differences in these virulence characteristics of isolates exposed to NRTIs were noted in most cases. However, at 24h and 72 h a significant increase in the rate of proliferation was observed in response to two-fold the peak concentration of lamivudine. The results suggest a limited effect of NRTIs on C. albicans virulence.

Causes of death in hospitalized adults with a premortem diagnosis of tuberculosis: an autopsy study.

OBJECTIVE: To ascertain the immediate and underlying causes of death in adults who died in hospital with a premortem diagnosis of tuberculosis. DESIGN: Causes of death were assessed independently by internists and pathologists in 50 adults admitted to two Soweto hospitals who died 24 h or more after admission. Detailed record reviews and complete autopsies, including HIV tests when not performed premortem, were performed. In addition, a variety of postmortem microbiological tests were performed. RESULTS: Forty-seven patients had HIV infection; all were antiretroviral naive. Their median age was 34.5 years, median CD4 cell count was 48 cells/microl and median length of hospitalization before death was 6 days. Autopsy confirmed the premortem diagnosis of tuberculosis in 37 HIV-infected patients (79%), whereas 10 (21%) did not demonstrate tuberculosis. Bronchopneumonia and cytomegalovirus pneumonitis were the leading pathologies in these 10 patients. In 47 HIV-infected cadavers immediate or contributory causes of death were: extensive pulmonary tuberculosis, 32 (68%); disseminated tuberculosis, 28 (60%); bacterial pneumonia, 13 (26%); cytomegalovirus pneumonitis in seven (15%); cytomegalovirus DNA was found in 31 (66%) and Pneumocystis pneumonia was found in five cadavers (11%). The lung, followed by lymph nodes, liver and kidney, were the commonest sites of tuberculosis. Mycobacterium tuberculosis was cultured from 19 spleens, one of which was multidrug resistant, and Salmonella spp. was cultured from 11 splenic specimens. CONCLUSION: We demonstrated disseminated, extensive tuberculosis associated with advanced HIV disease. Severe bacterial infections, including salmonellosis, were the leading co-morbidity, suggesting that hospitalized HIV-infected adults in whom tuberculosis is suspected may benefit from broad-spectrum antibiotic therapy.

Role of hippocampal Cav1.2 Ca2+ channels in NMDA receptor-independent synaptic plasticity and spatial memory.

Current knowledge about the molecular mechanisms of NMDA receptor (NMDAR)-independent long-term potentiation (LTP) in the hippocampus and its function for memory formation in the behaving animal is limited. NMDAR-independent LTP in the CA1 region is thought to require activity of postsynaptic L-type voltage-dependent Ca2+ channels (Cav1.x), but the underlying channel isoform remains unknown. We evaluated the function of the Cav1.2 L-type Ca2+ channel for spatial learning, synaptic plasticity, and triggering of learning-associated biochemical processes using a mouse line with an inactivation of the CACNA1C (Cav1.2) gene in the hippocampus and neocortex (Cav1.2(HCKO)). This model shows (1) a selective loss of protein synthesis-dependent NMDAR-independent Schaffer collateral/CA1 late-phase LTP (L-LTP), (2) a severe impairment of hippocampus-dependent spatial memory, and (3) decreased activation of the mitogen-activated protein kinase (MAPK) pathway and reduced cAMP response element (CRE)-dependent transcription in CA1 pyramidal neurons. Our results provide strong evidence for a role of L-type Ca2+ channel-dependent, NMDAR-independent hippocampal L-LTP in the formation of spatial memory in the behaving animal and for a function of the MAPK/CREB (CRE-binding protein) signaling cascade in linking Cav1.2 channel-mediated Ca2+ influx to either process.

Interhospital transfer of pan-resistant Acinetobacter strains in Johannesburg, South Africa.

BACKGROUND: Acinetobacter species infections are increasingly found to cause nosocomial infections, particularly in intensive care units. These pathogens are difficult to eliminate from the hospital environment, and the emergence of multiple-drug-resistant strains complicates patient treatment. In this retrospective study, several strains were analyzed to study the possible spread of pan-resistant strains. METHODS: Macrorestriction analysis was performed on isolates collected in July 2001 from Johannesburg Hospital and strains collected from a number of hospitals in Johannesburg a year later. RESULTS: A strain endemic to Johannesburg Hospital that was cefepime and ceftazidime sensitive in 2001 developed resistance to these antibiotics within 1 year. This and other resistant strains were found to have spread among academic and private hospitals in the area by July 2002. CONCLUSIONS: The development of resistance is believed to be a response to antibiotic pressure and the spread of resistant strains a result of health care worker and/or patient transfer among hospitals. This snapshot epidemiologic study highlights the need to institute stricter infection control measures to limit the spread of organisms such as Acinetobacter among hospitals.

National sentinel site surveillance for antimicrobial resistance in Klebsiella pneumoniae isolates in South Africa, 2010 - 2012.

BACKGROUND: The increasing rates of antimicrobial resistance observed in the nosocomial pathogen Klebsiella pneumoniae are of major public health concern worldwide. OBJECTIVES: To describe the antibiotic susceptibility profiles of K. pneumoniae isolates from bacteraemic patients submitted by sentinel laboratories in five regions of South Africa from mid-2010 to mid-2012. Molecular methods were used to detect the most commonly found extended-spectrum beta-lactamase (ESBL) and carbapenemase resistance genes. METHODS: Thirteen academic centres serving the public healthcare sector in Gauteng, KwaZulu-Natal, Free State, Limpopo and Western Cape provinces submitted K. pneumoniae isolates from patients with bloodstream infections. Vitek 2 and MicroScan instruments were used for organism identification and susceptibility testing. Multiplex polymerase chain reactions (PCRs) were used to detect blaCTX-M, blaSHV and blaTEM genes in a proportion of the ESBL isolates. All isolates exhibiting reduced susceptibility to carbapenems were PCR tested for blaKPC and blaNDM-1 resistance genes. RESULTS: Overall, 68.3% of the 2,774 isolates were ESBL-positive, showing resistance to cefotaxime, ceftazidime and cefepime. Furthermore, 46.5% of all isolates were resistant to ciprofloxacin and 33.1% to piperacillin-tazobactam. The major ESBL genes were abundantly present in the sample analysed. Most isolates (95.5%) were susceptible to the carbapenems tested, and no isolates were positive for blaKPC or blaNDM-1. There was a trend towards a decrease in susceptibility to most antibiotics. CONCLUSION: The high proportion of ESBL-producing K. pneumoniae isolates observed, and the prevalence of ESBL genes, are of great concern. Our findings represent a baseline for further surveillance in SA, and can be used for policy and treatment decisions.

Calcium channel alpha2delta subunits: differential expression, function, and drug binding.

Voltage-activated calcium channels are transmembrane proteins that act as transducers of electrical signals into numerous intracellular activities. On the basis of their electrophysiological properties they are classified as high- and low-voltage-activated calcium channels. High-voltage-activated calcium channels are heterooligomeric proteins consisting of a pore-forming alpha1 subunit and auxiliary alpha2delta, beta, and--in some tissues--gamma subunits. Auxiliary subunits support the membrane trafficking of the alpha1 subunit and modulate the kinetic properties of the channel. In particular, the alpha2delta subunit has been shown to modify the biophysical and pharmacological properties of the alpha1 subunit. The alpha2delta subunit is posttranslationally cleaved to form disulfide-linked alpha2 and, delta proteins, both of which are heavily glycosylated. Recently it was shown that at least four genes encode for alpha2delta subunits which are expressed in a tissue-specific manner. Their biophysical properties were characterized in coexpression studies with high- and low-voltage-activated calcium channels. Mutations in the gene encoding alpha2delta-2 have been found to underlie the ducky phenotype. This mouse mutant is a model for absence epilepsy and is characterized by spike wave seizures and cerebellar ataxia. Alpha2delta subunits can also support pharmacological interactions with drugs that are used for the treatment of epilepsy and neuropathic pain.