Open Microbiology Journal最新文献

Background: The Gp07 protein of aureophage Phi11 exhibits growth inhibitory effects when overexpressed in E. coli .The protein harbors two domains- an amino terminal Bro-like domain and a carboxy terminal Ant superfamily like KilA domain, of which the KilA domain retains the growth inhibitory effect of Gp07.

Methods: We studied the effects exerted by the overexpression of Gp07 and its separate domains upon the growth rate as well as the morphology of the E. coli cells. Additionally, we generated a mutant of Gp07 (designated as ΔGp07) by deleting the first eleven amino acid residues from the amino-terminal region of Gp07, and studied its growth inhibitory effects upon E. coli.

Results: Our results indicate that Gp07, ΔGp07 as well as the Carboxy-terminal region of Gp07 upon overexpression, retards the growth rate of the E. coli cells and also induces filamentation in the cells. Surprisingly, our data clearly suggests that the growth inhibition and filamentation induced by the the amino-terminal domain of Gp07 is temporal in nature.

Conclusion: The carboxy-terminal of domain of gp07 is essential for its activity.

Introduction: Mango juice has always been considered as a delicious, nutritious popular drink, but processed juice may not always be safe due to chemical and microbial risks. Determination of physicochemical and microbiological qualities of some packed mango juices of Bangladesh will help consumers to know the present scenario.

Material and methods: Six commercially available different juice samples were collected from the market. Carbohydrate profiles were determined using HPLC, crude protein content was calculated using the Kjeldahl method and other parameters were determined by standard AOAC methods. Standard culture techniques were followed to assess the total viable count (TVC), E. coli and other fecal coliforms.

Results: The highest quantity of monosaccharide (58.88%) was recorded in the AC1ME5 brand, while the lowest in Homemade (5.648%) and MN1GL2 (9.867%). The maximum content of acidity recorded was 0.24% and minimum 0.21%. The TSS content of all samples varied from 19% to 12%. The highest quantity 6.87% and the lowest 3.62% of reducing sugar were recorded. Most of the mango juices were low in protein and very low/negligible in fat content. Total viable count of different types of fruit juices varied from 1×10³ - 3×10³ CFU/ml. No significant amount of E. coli and fecal coliform was detected.

Conclusion: It can be concluded that the locally available mango juices contain a safe level of nutritional and microbial elements for human consumption, but not highly satisfactory.

Introduction: Acinetobacterb aumannii (A. baumannii) is an important pathogen in health care associated infections. Quinolone resistance has emerged in this pathogen.

Aims & objectives: The aim of the present study was to determine the presence of mutations of gyrA gene and parC genes by Restriction Fragment Length Polymorphism Polymerase Chain Reaction (RFLP-PCR) among clinical isolates of A. baumanii.

Materials and methods: The study was carried out on 140 clinical isolates of A. baumannii. The isolates were subjected to molecular study of mutations of gyrA gene and parC genes by RFLP-PCR beside determination of Minimal Inhibitory Concentration (MIC) by macro dilution tube method.

Results: The isolates of A. baumannii were resistant to ciprofloxacine and levofloxacin at MIC >4 µg/ml. The most isolates had MIC >128 µg/ml (42.3%). All resistant strains to ciprofloxacin of A. baumannii had mutations in gyrA and parC. The most frequent mutations were combined mutations in both genes (85.5%) and 5% had single mutation either in gyrA or parC. The most frequently combined mutations were associated with MIC >128 µg/ml (42.3%).

Conclusion: From this study we can conclude that resistance to ciprofloxacin was common in clinical isolates of A. baumannii. The most frequent mutations were present in gyrA and parC. However, mutations in parC alone were not uncommon. Further large scale studies are required to elucidate the resistance pattern of A. baumannii and its molecular mechanisms.

Introduction: CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loci as novel and applicable regions in prokaryotic genomes have gained great attraction in the post genomics era.

Methods: These unique regions are diverse in number and sequence composition in different pathogenic bacteria and thereby can be a suitable candidate for molecular epidemiology and genotyping studies. Results:Furthermore, the arrayed structure of CRISPR loci (several unique repeats spaced with the variable sequence) and associated cas genes act as an active prokaryotic immune system against viral replication and conjugative elements. This property can be used as a tool for RNA editing in bioengineering studies.

Conclusion: The aim of this review was to survey some details about the history, nature, and potential applications of CRISPR arrays in both genetic engineering and bacterial genotyping studies.

Background: Livestock production should respond to societal, environmental and economic changes. Since 2006 and the ban on antibiotics as growth factors in European Union, the use of probiotics has become widespread and has demonstrated the effect of intestinal microbiota on the performance of farm animals.

Objective: The aim of this study was to investigate the effect of supplementation with Lactobacillus salivarius (as a probiotics strain or combined with other strains) on zootechnical performance, metabolic and immune gene expression and intestinal microbiota diversity in mule ducks using high-throughput sequencing and real-time PCR.

Method: The mule ducks were reared for 79 days and overfed for 12 days with or without probiotics. Samples were collected at 14 (starting period) and 91 days (end of overfeeding period), 3 hours post feeding.

Results: Irrespective of digestive content, age, level of feed intake or supplementation with probiotics, Firmicutes, Proteobacteria and Bacteroidetes were the dominant phyla in the bacterial community in mule ducks. At 14 days, both the ileal and cecal samples were dominated by Firmicutes (in particular the Clostridiales order). Overfeeding induced a shift between Clostridiales and Lactobacillales in the ileal samples whereas in the cecal samples, the relative abundance of Firmicutes decreased. Overfeeding also induced hepatic over-expression of Fatty Acid Synthase (FAS) and of the lipid transporter gene Fatty Acid Binding Protein 4 (FABP4). This increase in lipid metabolism genes is associated with a decrease in inflammatory response.

Conclusion: Finally, probiotic supplementation had only a slight impact on gene expression and microbiota diversity, both at 14 days and after overfeeding.

Background: Tuberculosis is one of the most important infectious diseases that has claimed its victims throughout much of known human history. With Koch's discovery of the tubercle bacillus as the etiologic agent of the disease, his sanitary and hygienic measures, which were based on his discovery and the development of a vaccine against tuberculosis by Albert Calmette and Camille Guérin in 1921, an attenuated Mycobacterium bovis strain, bacilli Calmette-Guérin (BCG), and the discovery of the first antibiotic against tuberculosis, streptomycin by Selman Waksman in 1943, soon led to the opinion that appropriate control measures had become available for tuberculosis and it had been assumed that the disease could ultimately be eradicated.The emergence of resistant strains of this bacteria and widespread distribution of the disease in the world, and the emergence of the AIDS epidemic destroyed any possibility of global control of tuberculosis in the foreseeable future.

Objectives: The purpose of this review is to highlight the current scientific literature on mycobacterial infections and provide an overview on the laboratory diagnosis of tuberculosis and non-tuberculosis infections based on conventional phenotypic and modern molecular assays.

Method: In this study, a number of 65 papers comprising 20 reviews, 9 case reports, and 36 original research in association with mycobacteriosis and the laboratory diagnosis of mycobacterial infections, were reviewed.

Results: Based on our analysis on the published documents methods applied for the laboratory diagnosis of tuberculosis are continually assessed and developed in order to achieve more rapid, less expensive, and accurate results. Acid-fast staining and culture for mycobacteria remain at the core of any diagnostic algorithm with the sensitivity of 20-70% and specificity of 95-98% for AFB microscopy and the sensitivity of 95% and the specificity of 98% for culture based diagnosis. Following growth in culture, molecular tests such as nucleic acid hybridization probes and DNA sequencing may be used for definitive species identification. Nucleic acid amplification methods provide the means for direct detection of Mycobacterium tuberculosis in respiratory specimens without the prerequisite to isolate or culture the organism, leading to more rapid diagnosis and better patient care.

Conclusion: As the researchers in a developing country, we strongly believe that despite significant advances in laboratory capacity, in many countries reliable confirmation of suspected mycobacterial diseases is hindered by a lack of knowledge on proper standardized methods, sufficient funds, suitably trained staff and laboratory supplies.

Introduction: Bacillus cereus is a gram positive bacilli found commonly in the soil and environment. It is a bacteria rarely associated with endocarditis.

Case history: Intravenous drug abuse, presence of valvular defects, pacemakers, immunodeficiency are some of the known risk factors for B.cereus endocarditis. We present here a case series of two patients with B.cereus endocarditis along with a review of the literature.

Conclusion: This is the first report of B.cereus endocarditis from India to the best of our knowledge.

Background: Respiratory infections are one of the commonest causes of morbidity and mortality related to infectious diseases worldwide. The emergence of antimicrobial resistance is a major global health problem which is well established in developing countries. Good clinical suspicion and correct laboratory identification of respiratory infection causing organisms followed by the appropriate management are needed to compact both community-acquired and nosocomial infection respiratory infections.

Objectives: A retrospective study was carried out to elucidate the etiology of respiratory infections in Sudan, as well as to guide the physician to the best antimicrobial alternatives used in the treatment of respiratory infection.

Method: Respiratory isolates that have been morphologically identified and biologically characterized were subjected to antibiotic susceptibility testing.

Results: A total of 1481 respiratory specimens were examined, recovering 377 organisms from 350 culture positive samples [225(59.7%) sputum, 94(24.9%) broncho-alveolar lavage (BAL), 58(15.4%) Pleural fluid], the commonest organisms were Klebsiella ssp. (25.20%) and mycobacterium tuberculosis (25.20%), followed by Staphylococcus aureus(19.89%) and Pseudomonas aeruginosa(8.49%). High rate of resistance of bacterial isolates was observed to Co-trimoxazole (BA), Ampicillin sulbactam (AS), Cefotaxime (CF) and Tetracycline (TE), being 80%, 72.3%, 68.8% and 66.9% respectively; on the other hand, very low resistance rate was found to Amikacin (AK) and Levofloxacin (LE), being 4.6% and 8.5%, respectively.

Conclusion: Guided prescription of antimicrobial agents must be implemented and controlled to limit further spread of antimicrobial resistance.

Background: In Nepal, introduction of GeneXpert MTB/RIF assay (Xpert assay) as an initial confirmation test for tuberculosis (TB) has been considered to have impact as a significant decrease in number of clinically diagnosed pulmonary tuberculosis (PTB) cases than previous years. This study aims to find out the distribution profile of suspected tuberculosis cases according to patients age, gender, treatment history and HIV status as well as to evaluate the utility of the Xpert assay over conventional acid-fast bacilli (AFB) staining method for the proper diagnosis of M. Tuberculosis in respiratory specimens from the tuberculosis (TB) suspected patient samples.

Methods: The prospective cross-sectional analytical study was conducted in National Anti-Tuberculosis Center (NATA) center- Biratnagar and Primary Healthcare Center (PHC) - Manglabare, Morang District, of eastern Nepal from January 2014 to August 2014. Laboratory investigation was done by conventional AFB staining followed by Xpert assay.

Results: A total of 1549 sputum samples were initially analyzed. AFB staining resulted in 1441 AFB smear negative samples and 88 AFB smear positive samples, whereas 20 samples were directly processed for Xpert assay. The male: female smear positive ratio was 2.8:1 and was higher among age groups (21-40) years. Tuberculosis among HIV patients was found 22.22%. Xpert assay demonstrates that out of 1441 smear negative AFB cases, 258 were found to have TB positive, whereas out of 88 smears positive AFB cases 12 were found to have TB negative. The sensitivity of the Xpert assay in patients classified as AFB smear positive was found 85.4% and the specificity in smear negative patients was 81%.

Conclusion: The study concluded that implementation of Gene Xpert MTB/RIF assay is a helpful tool for early and rapid detection of tuberculosis with greater sensitivity and specificity over traditional AFB staining techniques.

Background: Access to clean and safe drinking water is still a problem in developing countries and more pronounced in rural areas. Due to erratic supply of potable, rural dwellers often seek for an alternative source of water to meet their basic water needs. The objective of this study is to monitor the microbiological and physicochemical water quality parameters of Nzhelele River which is a major alternative source of drinking water to villages along its course in Limpopo province of South Africa.

Methods: Membrane filtration method was employed in evaluating the levels of E. coli and Enterococci in the river water from January-June, 2014. Specialized multimeter was used to measure the pH, electrical conductivity and turbidity of the river water. Ion Chromatograph was used to measure major anions such as fluoride, chloride, nitrate and sulphate in the water.

Results: High levels of E. coli (1 x 10² - 8 x 10⁴ cfu/100 mL) and enterococci (1 x 10² - 5.7 x 10³ cfu/100 mL) were found in the river water and exceeded their permissible limits of 0 cfu/100 mL for drinking water. Turbidity values ranged from 1.12-739.9 NTU. The pH, electrical conductivity, chloride, fluoride, nitrate and sulphate levels were below their permissible limits for drinking water.

Conclusion: The river water is contaminated with faecal organisms and is unfit for drinking purposes. However, the levels of the major anions accessed were within the permissible limits of drinking water.