Spontaneous Cleavages of a Heterologous Protein, the CenA Endoglucanase of Cellulomonas fimi, in Escherichia coli

CenA is an endoglucanase secreted by the Gram-positive cellulolytic bacterium, Cellulomonas fimi, to the environment as a glycosylated protein. The role of glycosylation in CenA is unclear. However, it seems not crucial for functional activity and secretion since the unglycosylated counterpart, recombinant CenA (rCenA), is both bioactive and secretable in Escherichia coli. Using a systematic screening approach, we have demonstrated that rCenA is subjected to spontaneous cleavages (SC) in both the cytoplasm and culture medium of E. coli, under the influence of different environmental factors. The cleavages were found to occur in both the cellulose-binding (CellBD) and catalytic domains, with a notably higher occurring rate detected in the former than the latter. In CellBD, the cleavages were shown to occur close to potential N-linked glycosylation sites, suggesting that these sites might serve as ‘attributive tags’ for differentiating rCenA from endogenous proteins and the points of initiation of SC. It is hypothesized that glycosylation plays a crucial role in protecting CenA from SC when interacting with cellulose in the environment. Subsequent to hydrolysis, SC would ensure the dissociation of CenA from the enzyme-substrate complex. Thus, our findings may help elucidate the mechanisms of protein turnover and enzymatic cellulolysis.

Isolation and Characterization of a Bacterial Strain Enterobacter cloacae (Accession No. KX438060.1) Capable of Degrading DDTs Under Aerobic Conditions and Its Use in Bioremediation of Contaminated Soil

DDT is one of the most persistent pesticides among all the different types of organo-chlorine pesticides used. Among all the degradation methods, bacterial degradation of DDT is most effective. The present study was conducted to isolate different bacteria present in waste samples which have the ability to degrade DDT present in the soil in the minimum possible period of time and to observe the effect of different physical and chemical properties of the soil samples. Many pesticide degrading bacteria were isolated and identified through cultural, biochemical tests and further identified by 16S RNA sequencing method. The most potent strain DDT 1 growth in mineral salt medium supplemented with DDT as the only source of carbon (5-100 PPM) and was monitored at an optical density of 600 nm. The growth parameters at different physio-chemical conditions were further optimized. The result showed that Enterobacter cloacae had maximum growth in 15 days. FTIR analysis of the residual DDT after 15 days incubation showed that Enterobacter cloacae was able to degrade pesticide into its further metabolites of DDD, DDE, DDNU and other components can be used for biodegradation of DDT present in contaminated soil and water ecosystems.

Letter to the Editor: Microbiota in the Respiratory System—A Possible Explanation to Age and Sex Variability in Susceptibility to SARS-CoV-2

The Human respiratory tract is colonized by a variety of microbes and the microbiota change as we age. In this perspective, literature support is presented for the hypothesis that the respiratory system microbiota could explain the differential age and sex breakdown amongst COVID-19 patients. The number of patients in the older and elderly adult group is higher than the other age groups. The perspective presents the possibility that certain genera of bacteria present in the respiratory system microbiota in children and young adults could be directly or through eliciting an immune response from the host, prevent full-fledged infection of SARS-CoV-2. The possibility also exists that the microbiota in older adults and the elderly population have bacteria that make it easier for the virus to cause infection. I call upon the scientific community to investigate the link between human microbiota and SARS-CoV-2 susceptibility to further understand the viral pathogenesis.

Pathogenic Bacterial Species in Locally Prepared Fresh Fruit Juices Sold in Juice Houses of Eastern Ethiopia

Fruit juices are important components of a healthy diet and a dietary source of nutrients, vitamins, and fiber and vital for human health. However, unless it is handled with safety and hygienic conditions, food can be a vehicle for the transmission of various agents of diseases resulting in food borne outbreaks. Thus, this study aimed to determine common pathogenic bacterial species in locally prepared fresh fruit juices sold in juice houses of Eastern Ethiopia. A cross-sectional study design was conducted from 1 January to 27 March 2020, in eastern Ethiopia. Seventy-eight juice samples were collected aseptically using a sterilized collecting jar from each juice house. Pour plate count method was used to determine Staphylococcus, Salmonella, and Shigella species. Finally, the data were analyzed using descriptive statistical tests such as Chi-square and Fisher’s exact tests. P-value of .05 was considered as a cut point for statistical significance. The study found Staphylococcus count ranged from 1.68 log CFU/mL with the mean value of 4.204 log CFU/mL. Overall, 58 (74.4%) of the fruit juice samples had Staphylococcus count, 19 (24.4%) had Salmonella and 12 (15.4%) had Shigella higher than the maximum permitted limit of Gulf standard, 2000 set for any type of fruit juice. In general, the study found more than two-thirds of fruit juice samples had at least 1 pathogenic bacteria species higher than the maximum permitted limit and potentially hazardous to consumer health. Thus, regular supervision and application of food hygiene and safety are essential to improve the quality of fruit juice and to prevent the consumption of contaminated fruit juices, which leads to food borne illness.

Comparative Analysis of Susceptibility and Severity of COVID-19 in Countries from the Eastern and the Western World Till March ‘21

Majority of the world’s human population today is affected by Covid-19. The disease has not only exhibited differences in susceptibility among people of different countries, but also the mortality rate. In general, Western world has been reporting a greater number of infected cases than eastern countries. Even the mortality rates are quite high there. The aim of this study was to analyse the data available on the infectivity and mortality rates of Covid-19 in different countries till March’21 and then reviewed the literature to find reasons for the differences in susceptibility and severity in eastern and western countries. The reasons for the observed differences may be: (i) Eastern countries followed stricter modalities and got grace period to create better healthcare facilities to tackle COVID-19. This probably also slowed the transmission of virus and its evolution, (ii) Vaccination policies in the east may have provided some immunity due to cross reactivity, (iii) Frequent exposure to infections at young age in eastern countries might be helping in better immunity, (iv) Mutations in viral genome may be geography based and (v) Genetic differences in the immune system of the hosts with respect to ACE receptors and MHC may be playing an important role. In this article, an attempt has been made to put forth and discuss these plausible reasons along with suitable evidences. These findings may help in future research on the diagnosis, treatment and prevention of Covid-19.

Antimicrobial Resistance in Salmonella Typhi Isolated From a Referral Hospital of Kathmandu, Nepal

Purpose: The morbidity and mortality due to typhoid fever can be significantly reduced with the use of effective antibiotics. At present, fluoroquinolones, third generation cephalosporins, and azithromycin are widely used to treat typhoid fever. However, changing antibiotic susceptibility among Salmonella Typhi and Salmonella Paratyphi poses a particular challenge to the therapeutic management of enteric fever. The objective of this study was to assess the antibiotic susceptibility pattern of Salmonella Typhi isolates. Patients and Methods: A total of 706 blood specimens were collected from febrile patients attending the outpatient department of Kathmandu Model Hospital during June to September, 2018. The antibiotic susceptibility testing for 11 different antibiotics (nalidixic acid, ciprofloxacin, ofloxacin, levofloxacin, cefixime, ceftriaxone, cefotaxime, azithromycin, cotrimoxazole, chloramphenicol, and amoxicillin) was performed by disk diffusion method. Furthermore, minimum inhibitory concentration (MIC) values of ciprofloxacin, ofloxacin, and azithromycin were determined by agar dilution method. Mutation at gyrA ser83 associated with reduced susceptibility to fluoroquinolones was determined by PCR-RFLP. Results: Out of 706 blood samples, 6.94% (n = 49) were culture positive for Salmonella enterica (S. Typhi, n = 46). It was revealed that 97.8% S. Typhi isolates were susceptible to conventional first-line antibiotics (ampicillin, chloramphenicol, and cotrimoxazole), 97.3% to cephalosporins and 95.7% to azithromycin. S. Typhi were either resistant or intermediately susceptible to fluoroquinolones: 97.8% to ciprofloxacin, 91.3% to ofloxacin, and 89.1% to levofloxacin. The MIC of ciprofloxacin, ofloxacin, and azithromycin for S. Typhi ranged from 0.008 to 32, 0.03 to 16, and 2 to 8 μg/mL, respectively. Out of 46 S. Typhi isolates, 44 (95.65%) had gyrA ser83 mutation. Conclusion: Fluoroquinolones have poor activity against Salmonella Typhi. The trends of increasing azithromycin MIC value among S. Typhi might limit its use for the treatment of typhoid fever. Effectiveness of conventional first-line antibiotics in vitro suggests considering their clinical use after large-scale studies.

Awareness Toward Mucormycosis Attack for COVID Patients

Risk groups for mucormycosis include persons with immunosuppressed immune system and uncontrolled diabetes. The patients suffering from corona virus or post covid patients have been found to be entrapped with this fungal infection due to suppression in the immune system. Also the major attack was reported in those patients who were in Intensive Care units. It arises due to the fungal infection of various species and can occur simultaneously with covid. The development of black fungus mostly affects lungs, eyes, brain, and skin and is not at all contagious. Proper diagnostic can only predict that the patient is in invasive attack of which mucor species. It is better to take prevention by wearing medicated masks, hand gloves, wearing glasses, avoid dusty and damp places.

Meningococcal Disease Burden in India: A Systematic Review and Meta-Analysis

Objective: To perform systematic review and meta-analysis of meningococcal disease burden in India. Methods: We searched publications on meningococcal disease in India between 1996 and 2020 using PubMed and Google Scholar. Prevalence (proportion) of Meningococcal meningitis and Case-fatality ratio (CFR) were pooled using random effects model. Other outcomes were pooled qualitatively. Results: The prevalence of Meningococcal meningitis in epidemic and endemic conditions was 12.1% (95% CI: 5.2-21.4) and 0.76% (95% CI: 0.3-1.4), respectively, with a CFR of 12.8% (95% CI: 6.8-20.4) in epidemic settings; N. meningitis caused 3.2% (95% CI: 1.6-5.3) of Acute Bacterial Meningitis (ABM) cases in endemic settings. The disease appeared in infants, adolescents, and adults with Serogroup A prevalence. Treatment and prophylaxis were limited to antibiotics despite increased resistance. Conclusion: The study reveals epidemic and endemic presence of the disease in India with high fatality and serogroup A prevalence. Further monitoring and immunization are required to prevent outbreaks.

Antibiotic Resistance and Plasmid Profiling of Escherichia coli Isolated from Human Sewage Samples

In developing countries, the occurrence of antibiotic resistance is increasing day by day and antibiotic resistant microorganisms are being found in almost every environmental setting. Plasmids are considered as the main vector in the procurement and propagation of antibiotic resistance in many microorganisms such as Escherichia coli ( E. coli). The goal of this study was to examine the antibiotic resistance and screening of plasmid in E. coli strains which were previously identified from human sewage samples. During this study antibiotic susceptibility of E. coli isolates were determined by Kirby-Bauer disk diffusion method against 5 antibiotics (ampicilin, ceftriaxone, amoxicillin, ciprofloxacin, azithromycin). Furthermore, plasmid extraction of each isolate was done according to the protocol of FavorPrepTMPlasmid Mini Kit and plasmid profiling was done by agarose gel electrophoresis. In antibiotic sensitivity test, all E. coli strains showed resistance to ampicilin, amoxicillin, and ceftriaxone. In the plasmid profiling, it was revealed that all the isolates of E. coli harbored plasmids. The plasmid sizes ranged from approximately 1.5 to 15 kb. The findings of this study prove the consequences of antibiotic resistance as well as relationship of plasmid with antibiotic resistance which necessitates proper surveillance on antibiotic usage in the developing countries.

SARS-CoV-2 as Enteric Virus in Wastewater: Which Risk on the Environment and Human Behavior?

Microorganisms such as viruses, bacteria, and protozoa are the cause of many waterborne human infections. These microbes are either naturally present in aquatic environments or transferred within them by fecal sources. They remain in these environments for varying lengths of time before contaminating a new host. With the emergence of the COVID-19 pandemic, some studies have reported the presence of viral nucleic acids in stool samples from COVID-19 patients, suggesting the possibility of fecal-oral transmission. The SARS-CoV-2 RNA was thereby detected in the wastewater of symptomatic and asymptomatic people with a risk to human and environmental health. In this work, we try to discuss the different potential sources of this contamination, the forms of persistence in the environment, the techniques of partial elimination, and the possibility of creating new reservoirs.