Metabolic adaptation of two in silico mutants of Mycobacterium tuberculosis during infection

ABSTRACT: Background: Up to date, Mycobacterium tuberculosis (Mtb) remains as the worst intracellular killer pathogen. To establish infection, inside the granuloma, Mtb reprograms its metabolism to support both growth and survival, keeping a balance between catabolism, anabolism and energy supply. Mtb knockouts with the faculty of being essential on a wide range of nutritional conditions are deemed as target candidates for tuberculosis (TB) treatment. Constraint-based genome-scale modeling is considered as a promising tool for evaluating genetic and nutritional perturbations on Mtb metabolic reprogramming. Nonetheless, few in silico assessments of the effect of nutritional conditions on Mtb’s vulnerability and metabolic adaptation have been carried out. Results: A genome-scale model (GEM) of Mtb, modified from the H37Rv iOSDD890, was used to explore the metabolic reprogramming of two Mtb knockout mutants (pfkA- and icl-mutants), lacking key enzymes of central carbon metabolism, while exposed to changing nutritional conditions (oxygen, and carbon and nitrogen sources). A combination of shadow pricing, sensitivity analysis, and flux distributions patterns allowed us to identify metabolic behaviors that are in agreement with phenotypes reported in the literature. During hypoxia, at high glucose consumption, the Mtb pfkA-mutant showed a detrimental growth effect derived from the accumulation of toxic sugar phosphate intermediates (glucose-6-phosphate and fructose-6-phosphate) along with an increment of carbon fluxes towards the reductive direction of the tricarboxylic acid cycle (TCA). Furthermore, metabolic reprogramming of the icl-mutant (icl1&icl2) showed the importance of the methylmalonyl pathway for the detoxification of propionyl-CoA, during growth at high fatty acid consumption rates and aerobic conditions. At elevated levels of fatty acid uptake and hypoxia, we found a drop in TCA cycle intermediate accumulation that might create redox imbalance. Finally, findings regarding Mtb-mutant metabolic adaptation associated with asparagine consumption and acetate, succinate and alanine production, were in agreement with literature reports. Conclusions: This study demonstrates the potential application of genome-scale modeling, flux balance analysis (FBA), phenotypic phase plane (PhPP) analysis and shadow pricing to generate valuable insights about Mtb metabolic reprogramming in the context of human granulomas

Neonatal outcomes according to different degrees of maternal morbidity: cross-sectional evidence from the Perinatal Information System (SIP) of the CLAP network

Background The burden of maternal morbidity in neonatal outcomes can vary with the adequacy of healthcare provision and tool implementation to improve monitoring. Such information is lacking in Latin American countries, where the decrease in severe maternal morbidity and maternal death remains challenging. Objectives To determine neonatal outcomes according to maternal characteristics, including different degrees of maternal morbidity in Latin American health facilities. Methods This is a secondary cross-sectional analysis of the Perinatal Information System (SIP) database from eight health facilities in five Latin American and Caribbean countries. Participants were all women delivering from August 2018 to June 2021, excluding cases of abortion, multiple pregnancies and missing information on perinatal outcomes. As primary and secondary outcome measures, neonatal near miss and neonatal death were measured according to maternal/pregnancy characteristics and degrees of maternal morbidity. Estimated adjusted prevalence ratios (PRadj) with their respective 95% CIs were reported. Results In total 85,863 live births were included, with 1,250 neonatal near miss (NNM) cases and 695 identified neonatal deaths. NNM and neonatal mortality ratios were 14.6 and 8.1 per 1,000 live births, respectively. Conditions independently associated with a NNM or neonatal death were the need for neonatal resuscitation (PRadj 16.73, 95% CI [13.29–21.05]), being single (PRadj 1.45, 95% CI [1.32–1.59]), maternal near miss or death (PRadj 1.64, 95% CI [1.14–2.37]), preeclampsia (PRadj 3.02, 95% CI [1.70–5.35]), eclampsia/HELPP (PRadj 1.50, 95% CI [1.16–1.94]), maternal age (years) (PRadj 1.01, 95% CI [<1.01–1.02]), major congenital anomalies (PRadj 3.21, 95% CI [1.43–7.23]), diabetes (PRadj 1.49, 95% CI [1.11–1.98]) and cardiac disease (PRadj 1.65, 95% CI [1.14–2.37]). Conclusion Maternal morbidity leads to worse neonatal outcomes, especially in women suffering maternal near miss or death. Based on SIP/PAHO database all these indicators may be helpful for routine situation monitoring in Latin America with the purpose of policy changes and improvement of maternal and neonatal health

The impact of maternal morbidity on cesarean section rates: exploring a Latin American network of sentinel facilities using the Robson’s Ten Group Classification System

Abstract Background Latin America has the highest Cesarean Section Rates (CSR) in the world. Robson’s Ten Group Classification System (RTGCS) was developed to enable understanding the CSR in different groups of women, classified according to obstetric characteristics into one of ten groups. The size of each CS group may provide helpful data on quality of care in a determined region or setting. Data can potentially be used to compare the impact of conditions such as maternal morbidity on CSR. The objective of this study is to understand the impact of Severe Maternal Morbidity (SMM) on CSR in ten different groups of RTGCS. Methods Secondary analysis of childbirth information from 2018 to 2021, including 8 health facilities from 5 Latin American and Caribbean countries (Bolivia, Guatemala, Honduras, Nicaragua, and the Dominican Republic), using a surveillance database (SIP-Perinatal Information System, in Spanish) implemented in different settings across Latin America. Women were classified into one of RTGCS. The frequency of each group and its respective CSR were described. Furthermore, the sample was divided into two groups, according to maternal outcomes: women without SMM and those who experienced SMM, considering Potentially Life-threatening Conditions, Maternal Near Miss and Maternal Death as the continuum of morbidity. Results Available data were obtained from 92,688 deliveries using the Robson Classification. Overall CSR was around 38%. Group 5 was responsible for almost one-third of cesarean sections. SMM occurred in 6.7% of cases. Among these cases, the overall CSR was almost 70% in this group. Group 10 had a major role (preterm deliveries). Group 5 (previous Cesarean section) had a very high CSR within the group, regardless of the occurrence of maternal morbidity (over 80%). Conclusion Cesarean section rate was higher in women experiencing SMM than in those without SMM in Latin America. SMM was associated with higher Cesarean section rates, especially in groups 1 and 3. Nevertheless, group 5 was the major contributor to the overall CSR

The burden of stillbirths in low resource settings in Latin America: Evidence from a network using an electronic surveillance system.

ObjectiveTo determine stillbirth ratio and its association with maternal, perinatal, and delivery characteristics, as well as geographic differences in Latin American countries (LAC).MethodsWe analysed data from the Perinatal Information System of the Latin American Center for Perinatology and Human Development (CLAP) between January 2018 and June 2021 in 8 health facilities from five LAC countries (Bolivia, Guatemala, Honduras, Nicaragua, and the Dominican Republic). Maternal, pregnancy, and delivery characteristics, in addition to pregnancy outcomes were reported. Estimates of association were tested using chi-square tests, and P ResultsIn total, 101,852 childbirths comprised the SIP database. For this analysis, we included 99,712 childbirths. There were 762 stillbirths during the study period; the Stillbirth ratio of 7.7/1,000 live births (ranged from 3.8 to 18.2/1,000 live births across the different maternities); 586 (76.9%) were antepartum stillbirths, 150 (19.7%) were intrapartum stillbirths and 26 (3.4%) with an ignored time of death. Stillbirth was significantly associated with women with diabetes (PRadj 2.36; 95%CI [1.25-4.46]), preeclampsia (PRadj 2.01; 95%CI [1.26-3.19]), maternal age (PRadj 1.04; 95%CI [1.02-1.05]), any medical condition (PRadj 1.48; 95%CI [1.24-1.76, and severe maternal outcome (PRadj 3.27; 95%CI [3.27-11.66]).ConclusionsPregnancy complications and maternal morbidity were significantly associated with stillbirths. The stillbirth ratios varied across the maternity hospitals, which highlights the importance for individual surveillance. Specialized antenatal and intrapartum care remains a priority, particularly for women who are at a higher risk of stillbirth