Open Microbiology Journal最新文献

Introduction: Increased incidence of carbapenem-resistant Enterobacteriaceae (CRE) has been reported worldwide. The WHO warns about the imminent risk to global health if the spread of resistant bacteria is not contained.

Materials and methods: Here, single molecule real time sequencing was used to analyse the whole genome and resistome of SKGH01, a strain of Klebsiella pneumoniae .

Results and discussions: The data showed that SKGH01 was resistant to all commercially available antibiotics. A complete account of extensively drug-resistant (XDR) CRE at a genomic level and the entire location map of all antibiotic resistance components are here presented. Additionally, this work proposes a model of XDR acquisition in Enterobacteriaceae.

Background: Safe water supply is vital and can result in significant benefits to health. However, contaminated bottled water poses a great health risk due to the poor microbiological quality of water.

Methods and materials: A retrospective study was conducted on 222 Bottled water samples collected from various regions of Ethiopia from January 2008 to December 2015, tested and recorded in Ethiopian Public Health Institute to determine heterotrophic plate count and Staphylococcus aureus by pour plate method; for coliforms using multiple tubes fermentation techniques; for mould and yeast count using spread method, and for Salmonellae and Shigella spp. using ES ISO 6579 and ES ISO 21567. The data was analyzed using SPSS 20 statistical package.

Results: Among the total samples examined from 44 brands, detections of heterotrophic plate count, mould, yeast, total and thermotolerant coliforms, Escherichia coli and Staphylococcus aureus were observed in 114 (51.4%), 33 (14.9%), 5 (2.3%), 2 (0.9%), 1 (0.5%), 1 (0.5%) and 1 (0.5%) samples respectively, but there were no detections of Salmonellae nor Shigellae species.

Conclusion: About 40% of bottled water samples were mycologically and bacteriologically unsafe for human consumption. To prevent public health hazards, regular monitoring of bottled water using quality indicators should be a priority agenda.

Introduction: Nowadays various biochemical markers, such as C-Reactive Protein (CRP), Procalcitonin and tumor necrosis factor alpha, have been proposed as a potential marker for screening neonatal sepsis. In the current study, we tried to see the diagnostic significance of White Blood Cell (WBC) count and CRP in diagnostic screening of neonatal sepsis.

Methods: A prospective cross-sectional study was conducted from May 2016 to April 2017 in Asella Teaching and Referral Hospital. Data were entered into EPI-INFO version 3.5.1 for cleanup and then exported to SPSS version 17 for further analysis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive values (NPV) were used to assess the accuracy of CRP and WBC count taking blood culture as gold standard.

Results: Data of 303 neonates with clinical sepsis were analyzed. Positive CRP and abnormal WBC were reported in 136(45%) and 99(32.7%) of study subjects respectively. Blood culture turned to be positive in 88(29.4%) of study subjects. The Sensitivity, Specificity, PPV and NPV of WBC count were 59.5 %, 79.6%, 52%, 64.5% respectively while the sensitivity, specificity, PPV and NPV of CRP were 65.6%, 78%, 42% and 91% respectively. By combining both WBC and CRP, the sensitivity, specificity, PPV and NPV improve to 78.5%, 83%, 60% and 93% respectively. CRP positivity rate was comparable across gram positive and gram negative bacteria while high WBC count were more reported among gram positive sepsis than gram negative ( OR 4.8, (95% CI 1.45-15.87, P 0.01).

Conclusion: Based on this study's finding, it can be concluded that CRP alone or in combination with WBC count showed better diagnostic accuracy in neonatal sepsis.

Introduction: Azomonas agilis, a nitrogen-fixing bacterium, was isolated from rhizospheric soil in central Myanmar.

Methods & materials: The nitrogen-fixing activity of this bacterium was detected by plate screening method using glucose nitrogen free mineral medium and ammonium test-kit Cellulolytic activity was screened by plat assay and detected by Dinitrosalicyclic acid method (DNS).

Results & discussion: The isolated A. agilis grew in media containing 3-12% of NaCl, although the growth became poor when NaCl concentrations increased. Among various carbon sources, sucrose was the best source for ammonium accumulation of this bacterium, whereas arabinose was not the suitable carbon source. Although the nitrogen-fixing activity of A. agilis was highest after one week incubation, cellulase enzyme production was highest after 2-3 days of incubation. It was observed that cellulase enzyme activity of A. agilis for cellulose and sodium carboxymethyl cellulose (CMC) was almost the same. Three agricultural wastes were used to detect the cellulase enzyme activity of A. agilis, cellulase activity was better on filter paper as a substrate when compared to rice-straw and sawdust.

Conclusion: So, the isolated A. agilis has high potential as an effective bacterial strain to use in sustainable agriculture and degradation of some agricultural residues.

Background: Tuberculosis (TB) is an extremely contagious disease detrimentally affecting virtually every organ, most importantly the lungs. Pulmonary complications have been one of the commonest causes of morbidity and mortality since the advent of AIDS (Acquired Immune Deficiency Syndrome) pandemic. The AIDS virus has considerably reshape the epidemiology of TB by widening the risk of reactivating latent TB, increasing the possibility of TB infection once contracted to tubercle bacilli (re-infection) and by elevating the risk of rapid progression instantly after the infection. In this background, this study is intended to understand the prevalence of pulmonary tuberculosis and associated factors amongst Human Immunodeficiency Virus (HIV) positive patients attending antiretroviral therapy (ART) clinic in Arba Minch General hospital during the study period (March to May, 2016).

Methods: A cross-sectional study was carried out at Arba Minch Hospital from March to May, 2016. To assess the associated factors, a pre-tested structured questionnaire has been used. Sputum samples were collected and examined microscopically by using acid fast staining. The data was analyzed using Statistical Package for Social Services, version 20.

Results: Totally, 291 HIV positive patients were included in this study of which 71.5% were females and 28.5% were males. It was found that 42.3% of respondents were in the age ranged between 31-40 years. Of the 291 patients screened, 21 were positively diagnosed with pulmonary TB making the overall prevalence rate of 7.2%. From this study, it was revealed that CD4 count, previous history of tuberculosis and smoking were the significant predictors of tuberculosis (p˂0.05) in HIV patients.

Conclusion: The results of the present study envisaged that the prevalence of HIV/TB co-infection was 7.2%. Previous history of TB, CD4 count less than 200/μl, and smoking habit were the possible risk factors elucidated. Therefore, TB screening among HIV-positive patients, public awareness, and community mobilization should be encouraged.

Introduction: New strategies have been arisen to set a rapid and effective screening for selection of microorganism with bioactive potential. This study suggests that combination of physicochemical pretreatments and taxonomic dereplication of microbial collections through MALDI-TOF MS, facilitates the detection of low abundance actinobacteria with potential as a source of antimicrobial agents.

Material and methods: An unstudied microbial community from a tropical river sediment in Colombian Orinoquía is described, applying an extended cultivation strategy using physicochemical pretreatments, biological screenings and taxonomic dereplication through MALDI-TOF MS approach.

Results: Actinobacteria-like isolates (790) were growth and their antimicrobial activity was assessed against methicillin-resistant Staphylococcus aureus, Vancomycin-resistant Enterococcus faecium, extended-spectrum β-lactamase Klebsiella pnumoniae, and clinical isolates of Cladosporium cladosporioides and Epicoccum nigrum. Seventy-eight isolates, belonging to the Streptomycetaceae family according to 16S rDNA analysis were found to have antimicrobial activity and were categorized as low abundance actinobacteria by MALDI-TOF MS.

Conclusion: The results suggest that combination of physicochemical pretreatments and taxonomic dereplication of microbial collections through MALDI-TOF MS, facilitates the detection of low abundance actinobacteria with potential as a source of antimicrobial agents.

Background: Bartonella species are intracellular bacteria capable of producing several diseases in humans. The three most common and wellknown diseases are cat scratch disease (CSD), caused by B. henselae, trench fever, caused by B. quintana and Carrion's Disease, caused by B. bacilliformis. Signs and symptoms are very different and aspecific: Fatigue, fever, headache, lymphadenopathy, malaise, loss of weight. No data exist to support guidelines' recommendations to decide which drugs should be optimally used and how long they should be administered. Therefore, a marker of treatment response is needed to guide treatment strategies.

Methods: We report herein three cases in which a species specific Reverse-Transcriptase Polymerase-Chain-Reaction (RT PCR) developed in-house was performed and compared to serology in order to make diagnosis and to evaluate treatment response.

Results: Our species-specific RT PCR seemed to play a fundamental role both in diagnosis and treatment. Moreover, a discrepancy with the serology results was found.

Conclusion: Further studies are necessary to validate these results and elucidate what is the best treatment for this pleomorphic disease. However, in absence of clear guidelines, RT PCR may be useful to orientate kind of treatment ad its duration.

Background: Pseudomonas aeruginosa is a ubiquitous free-living bacterium and is responsible for severe nosocomial infections, life-threatening infections in immune compromised persons. The bacterium, along with its natural resistance, can acquire resistance to many antibiotics by a variety of methods.

Method: Therefore, to compare the antibiotic sensitivity pattern of Pseudomonas aeruginosa, a total of seventeen isolates of P. aeruginosa were isolated from different sources; for example environmental sources, frozen food sources, clinical sources and medical waste materials. Isolates were confirmed to be P. aeruginosa by cultural and biochemical properties.

Result: The isolates were tested against seventeen commercially available antibiotics to observe the antibiotic susceptibility patterns. Imipenem and meropenem were the most potent antibiotics (100% sensitivity) followed by amikacin and piperacillin with maximum sensitivity. Among others, gentamicin, ciprofloxacin, levofloxacin and aztreonam were found to be fairly active. A good number of isolates were intermediately resistant to ceftriaxone. The rates of resistance to aztreonam, cefotaxime and ceftazidime were 11.76%, 82.35% and 5.88% respectively. Complete resistance was observed against penicillin, ampicillin, cefixime and cefpodoxime.

Conclusion: It can be concluded that the clinical isolates including isolate from medical waste, were multi-drug resistant than environmental and food isolates indicating the risk of transmission of resistance to the environmental isolates of P. aeruginosa.

Background: Staphylococcus aureus is a Gram-positive bacterium that causes severe illnesses in the human population. The capacity of S. aureus strains to form biofilms on biotic and abiotic surfaces creates serious problems for treatment of hospital infections and has stimulated efforts to develop new means of specific protection or immunotherapy.

Material and methods: We found that rabbit serum raised against crude concentrated S. aureus liquid culture significantly decreased the development of staphylococcal biofilm in vitro. To discover the corresponding staphylococcal antigen, we used mass-spectrometry and molecular cloning and identified three major immunodominant proteins. They included α-haemolysin, serine proteinase SplB and S. aureus surface protein G, known as adhesin SasG.

Results: Although according to literature data, all these proteins represent virulence factors of S. aureus and play diverse and important roles in the pathogenesis of staphylococcal diseases, only SasG can be directly implicated into the biofilm formation because of its surface location on a staphylococcal cell. Indeed, rabbit serum directed against purified recombinant SasG, similar to serum against crude staphylococcal liquid culture, prevented the formation of a biofilm.

Conclusion: SasG can be considered as a target in an anti-biofilm drug development and a component of the vaccine or immunotherapeutic preparations directed against staphylococcal infections in humans.

Introduction: Anaerobic digestion for methane production comprises of an exceptionally diverse microbial consortium, a profound understanding about which is still constrained. In this study, the methanogenic archaeal communities in three full-scale anaerobic digesters of a Municipal Wastewater Treatment Plant were analyzed by Fluorescence in situ hybridization and quantitative real-time Polymerase Chain Reaction (qPCR) technique.

Methods & materials: Fluorescence in situ hybridization (FISH) was performed to detect and quantify the methanogenic Archaea in the sludge samples whereas qPCR was carried out to support the FISH analysis. Multiple probes targeting domain archaea, different orders and families of Archaea were used for the studies.

Results and discussion: In general, the aceticlastic organisms (Methanosarcinaceae & Methanosaetaceae) were more abundant than the hydrogenotrophic organisms (Methanobacteriales, Methanomicrobiales, Methanobacteriaceae & Methanococcales). Both FISH and qPCR indicated that family Methanosaetaceae was the most abundant suggesting that aceticlastic methanogenesis is probably the dominant methane production pathway in these digesters.

Conclusion: Future work involving high-throughput sequencing methods and correlating archaeal communities with the main operational parameters of anaerobic digesters will help to obtain a better understanding of the dynamics of the methanogenic archaeal community in wastewater treatment plants in United Arab Emirates (UAE) which in turn would lead to improved performance of anaerobic sludge digesters.