Molecular, biochemical and pharmacological characterisation of Mycobacterium tuberculosis cytochrome bd-I oxidase: a putative therapeutic target

Tuberculosis (TB) remains one of the most devastating diseases in humans. Nowadays, tuberculosis therapy is not sufficient to control the TB epidemic and only lasts for 6 months to cure patients and prevent relapse; therefore, the treatment of Mycobacterium tuberculosis (Mtb) is particularly challenging (1). New antibiotics, mainly those that are derived from new chemical classes, are more likely to be more effective against resistant strains. Moreover, expanding the knowledge of the mode of action of drugs has important implications in tackling TB. Only empirical approaches can be adopted in the journey of discovering new anti-tubercular drugs until a clear picture of latency and persister cells’ physiology is achieved. Mtb has the extraordinary ability to survive under hypoxia, suggesting a high degree of metabolic plasticity. The flexibility conferred by a modular respiratory system is critical to the survival of Mtb, thereby also making it a promising area of research for new drug targets. This thesis aimed towards the characterisation of cytochrome bd-I quinol oxidase (bd-I), a respiratory component that is believed to operate during both the replicative and “dormant” Mtb phenotypes. The essential nature of Mtb bd-I, which has no human homologue, has been confirmed in a recent deep sequencing study of genes required for Mtb growth by Griffin et al. (2), further confirming its potential as a novel target. Recombinant Mtb bd-I was successfully expressed under the control of the pUC19 lac promoter in the Escherichia coli ML16 bo3/bd-I and MB44 bo3/bd-I/bd-II knockout strains, allowing “noise-free” measurement of the enzyme. Initial steady-state kinetics of the enzyme was presented using a range of quinol substrates, revealing a substrate preference for dQH2 over Q1H2 and Q2H2. A number of bd-I inhibitors were identified and their pharmacodynamic profiles against Mtb H37Rv were determined. In addition, a pharmaco-metabolomics platform was initiated to explore the cellular response of Mtb to current first-line TB drugs as well as in house bd-I and type II NADH inhibitors. The initial findings are discussed in the context of the known mode of action of the drugs and future research needs in drug discovery of this devastating disease

Identification of 2-Aryl-Quinolone Inhibitors of Cytochrome bd and Chemical Validation of Combination Strategies for Respiratory Inhibitors against Mycobacterium tuberculosis

Mycobacterium tuberculosis cytochrome bd quinol oxidase (cyt bd), the alternative terminal oxidase of the respiratory chain, has been identified as playing a key role during chronic infection and presents a putative target for the development of novel antitubercular agents. Here, we report confirmation of successful heterologous expression of M. tuberculosis cytochrome bd. The heterologous M. tuberculosis cytochrome bd expression system was used to identify a chemical series of inhibitors based on the 2-aryl-quinolone pharmacophore. Cytochrome bd inhibitors displayed modest efficacy in M. tuberculosis growth suppression assays together with a bacteriostatic phenotype in time-kill curve assays. Significantly, however, inhibitor combinations containing our front-runner cyt bd inhibitor CK-2-63 with either cyt bcc-aa3 inhibitors (e.g., Q203) and/or adenosine triphosphate (ATP) synthase inhibitors (e.g., bedaquiline) displayed enhanced efficacy with respect to the reduction of mycobacterium oxygen consumption, growth suppression, and in vitro sterilization kinetics. In vivo combinations of Q203 and CK-2-63 resulted in a modest lowering of lung burden compared to treatment with Q203 alone. The reduced efficacy in the in vivo experiments compared to in vitro experiments was shown to be a result of high plasma protein binding and a low unbound drug exposure at the target site. While further development is required to improve the tractability of cyt bd inhibitors for clinical evaluation, these data support the approach of using small-molecule inhibitors to target multiple components of the branched respiratory chain of M. tuberculosis as a combination strategy to improve therapeutic and pharmacokinetic/pharmacodynamic (PK/PD) indices related to efficacy

Ameliorative role of Ziziphus spina-christi leaf extracts against hepatic injury induced by Plasmodium chabaudi infected erythrocytes

One of the most common deadliest parasitic diseases is Malaria. The biology and the pathogenesis of this fascinating parasite are not yet fully understood which make discovering effective alternative drugs a challenging task. Moreover, the emergence of resistant strains added an additional burden in the journey of malaria elimination. Traditional medicine used to be an alternative therapy choice owing to the presence of potent natural products. Ziziphus spina-christi (L.) considered being one of the common potent natural plant in gulf region and other nations. Therefore, this study designed to evaluate the ameliorative role of Z. spina-christi leaf extracts (ZSCLE) against Plasmodium chabaudi-induced hepatic injury. The study involved three groups were as follows; a vehicle control group, infected with 106P. chabaudi-parasitized erythrocytes group and ZSCLE treated-infected mice with 106P. chabaudi-parasitized erythrocytes group. The results showed a remarkable reduction of parasitemia level and notable reverse of the anemic picture among ZSCLE treated-infected mice. The effects of ZSCLE on the liver functions enzymes and on the histopathological pictures of liver were significant. It could be concluded that Z. spina-christi leaf extracts have a protective role against Plasmodium infection that also marked through significant restoration of hepatic oxidative markers. Keywords: Malaria, Ziziphus spina-christi, Liver, Histology, Oxidative stress, Mic

Helicobacter pylori Infection: Comparison of Knowledge between Health Science and Non-Health Science University Students

Background: Helicobacter pylori (H. pylori), an important human pathogen, is classified as a human carcinogen. It is known to cause dyspepsia, peptic ulcers, and gastric cancer. Awareness regarding H. pylori infections in Saudi Arabia awaits investigation to reduce or even eliminate the infection that would ease the substantial burden of managing H. pylori among both malignant and non-malignant diseases. Aims: The study aims were to (1) assess the knowledge of H. pylori infection, testing, and management among undergraduate students in Saudi Arabia and (2) compare the H. pylori knowledge among health science and non-health science students. Methods: This study involved a cross-sectional online survey among 334 undergraduate students in health science and non-health science colleges at King Saud University, Saudi Arabia, using a valid and reliable author-developed survey. The survey had two sections: the socio-demographic factors and knowledge items regarding H. pylori. Data were collected during the 2019–2020 academic year. Data analysis included descriptive statistics, Chi-square, and Mann–Whitney U test. The knowledge scores were categorized as poor, fair, and good. Results: Less than 10% of the students in both groups had a good knowledge level about H. pylori. The comparison of the overall mean between both groups was non-significant. Moreover, the level of knowledge of the respondents was significantly associated with their university level (p < 0.001), family monthly income (p < 0.007), having heard about H. pylori infection (p < 000.1), and a previous history of H. pylori infection (p < 000.1). Conclusion: The overall knowledge level of Saudi undergraduate students about H. pylori infection was low. Thus, health awareness interventions through educational programs are recommended for improving their knowledge about H. pylori infection and its prevention

<i>Stenotrophomonas maltophilia</i> Epidemiology, Resistance Characteristics, and Clinical Outcomes: Understanding of the Recent Three Years’ Trends

Background. Stenotrophomonas maltophilia is an emerging pathogen classified as a public health concern, that infects critically ill patients and has expressed resistance against antimicrobial therapy. The aim of this study was to examine the epidemiological pattern, resistance characteristics and clinical outcomes of S. maltophilia infections in hospitalized patients. Methods. The study included 393 S. maltophilia isolates from different clinical specimens as well as the clinical data of 209 Intensive Care Unit (ICU) patients. The patients’ data were obtained from medical and laboratory files. Descriptive statistics and a univariate analysis were used to report and compare the demographics, clinical data, and outcomes. Results. The S. maltophilia was mostly isolated from the respiratory specimens of ICU patients. The adult patients were more likely to develop serious infections and worse outcomes than were pediatric patients. The most common co-infecting pathogens were SARS-CoV2 and Pseudomonas aeruginosa. The death rate was 44.5% and increased to 47.1% in the case of a respiratory infection. Septic shock was the most significant predictor of mortality. Older age and mechanical ventilation were independent and significant risk factors that worsened the outcomes in patients with respiratory infections. Conclusions. The identification of S. maltophilia as a threat highlights the importance of surveillance studies in this region

Klebsiella pneumoniae bacteraemia epidemiology: resistance profiles and clinical outcome of King Fahad Medical City isolates, Riyadh, Saudi Arabia

Abstract Background and objectives Klebsiella pneumoniae (K. pneumoniae) is the second leading cause of community-acquired and hospital-acquired gram-negative bloodstream infection (BSI). This study aimed to assess the epidemiological and microbial-resistance characteristics and clinical factors associated with K. pneumoniae BSI in Saudi Arabia. Materials and Methods Data of 152 K. pneumoniae isolates diagnosed between January 2019 and January 2020 at King Fahad Medical City, Riyadh, Saudi Arabia were evaluated retrospectively. Clinical records of the patients were collected and analysed statistically. Results In total, 152 cases of K. pneumoniae BSI were identified. Adult patients (66.4%) were at a higher risk of developing the infection than paediatric patients (33.6%). The rate of infection was slightly higher in women than in men. Neurological disorders were the predominant underlying conditions for the acquisition of K. pneumoniae BSI, at all ages. Most of the deceased patients were adults with multi-organ dysfunction. Klebsiella pneumoniae showed disturbing resistance to amoxicillin-clavulanate and cefuroxime (72.4%), ceftazidime (67.8), cephalothin (76.3%), and to Carbapenems (36.1%). Conclusions The impact of K. pneumoniae BSI was seen not only at the patient level, but also at the community level, and was related to multi-drug resistant infection. These findings provide a better understanding of microbial resistance and its association with patient clinical outcomes

Blood Biomarkers of Neonatal Sepsis with Special Emphasis on the Monocyte Distribution Width Value as an Early Sepsis Index

Background and Objectives: Early detection of neonatal sepsis is critical because it is potentially fatal. Therefore, sepsis biomarkers of sufficient sensitivity and specificity are needed. This study aimed to evaluate the utility of peripheral blood parameters as neonatal sepsis biomarkers and the diagnostic performance of the monocyte distribution width (MDW) in sepsis in a neonatal intensive care unit. Materials and Methods: A cross-sectional study was conducted from September 2019 to August 2020 at the King Saud University Medical City in Riyadh, Saudi Arabia. Samples were collected and organised as follows: 77 study cases were subdivided into two subgroups (other health complication (49) and sepsis (28)), and there were 70 controls. The causative microorganisms of neonatal sepsis were isolated. Peripheral blood samples were collected from each neonate in an ethylenediaminetetraacetic acid tube for a complete blood count and a leukocyte differential count. Moreover, the receiver operating characteristic (ROC) curve analysis was used to measure the diagnostic performance of the MDW. Results: The haematological parameters and neonatal sepsis cases had a considerable correlation. The MDW was the most significant haematological parameter. The ROC analysis of the MDW demonstrated that the area under the curve was 0.89 (95% confidence interval: 0.867 to 0.998) with a sensitivity of 89.3%, a specificity of 88.2%, and a negative predictive value of 97.2% at the cut-off point of 23. Conclusions: The use of haematological parameters is feasible and can be performed rapidly. Neonatal sepsis showed a strong correlation with leukopenia, anaemia, thrombocytopenia, and an elevated MDW value. Moreover, the ROC curve analysis confirmed the high diagnostic ability of the MDW in neonatal sepsis prediction

Rotavirus and norovirus infections in children in Sana&apos;a, Yemen

Summary objectives To describe the epidemiology of rotavirus and norovirus infection among children with acute gastroenteritis in Sana&apos;a, Yemen. conclusions Rotavirus and norovirus infections are common causes of gastroenteritis in Yemen. Rotavirus vaccines could play a significant role in the control of acute childhood diarrhoea in this setting. keywords norovirus, rotavirus, Yeme

Prevalence of residual risks of the transfusion-transmitted infections in Riyadh hospitals: A two-year retrospective study

This study aimed to evaluate the prevalence and trends of transfusion-transmitted infections (TTIs) in two hospitals in Riyadh, as well as to judge the best type of tests to ensure blood transfusion safety. By using serological and nucleic acid test (NAT) tests, these donors were screened for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), human T-lymphotropic virus type 1 (HTLV-1), human T-lymphotropic virus type 2 (HTLV-2), syphilis, and malaria infection as a first time of donation. Out of 58,898 blood units, 336 units were reacted for HBsAg, 5,318 units for HBcAbs, 506 units for HCV antibodies, 214 units for HIV Ab/Ag combinations, 206 units for HTLV antibodies, 355 units for syphilis antibodies, and 81 units for malaria. Moreover, the genotypic prevalence of these products showed that 349 units reacted for HBV DNA, HCV RNA, and HIV RNA in blood donation. This study reflects the seriousness of the residual risk of TTI, which is still a threat factor for the transmission of blood-borne infectious diseases. It was discovered that utilising (NAT) could increase test sensitivities while also lowering residual TTI risks, improving blood safety, and being cost-effective