Ml Of Bacteria Research Articles

Biocidal and synergistic effect of three types of biologically synthesised silver/silver chloride nanoparticles.

Three types of silver/silver chloride nanoparticles were obtained by green synthesis from three types of microbial biomass. Their biocidal capacity was tested against six microorganisms. Two filamentous fungi were used that had previously demonstrated the ability to synthesise nanoparticles, Penicillium sp. 8L2 and Botryosphaeria rhodina MAMB-05. Also, the synthesis capacity of a yeast, Rhodotorula mucilaginosa 1S1, was evaluated. The original protocols underwent slight modifications. At the same time, the fractional inhibitory concentration was obtained. The interaction between specific antibiotics and the nanoparticles that showed the greatest biocidal capacity came from Penicillium sp.8L2, and it was studied further. All nanoparticles were characterised by UV-vis spectrophotometry and transmission electron microscopy (TEM). Also, their size distribution was analysed, which was in the range of 4 to 34nm. The biocidal capacity of the nanoparticles for a group of bacteria and fungi was studied, presenting very low values in the range of 2.5-10µg/mL for bacteria and 4-256µg/mL for fungi. The interactions between the nanoparticles synthesised by Penicillium sp. 8L2 and a group of specific antibiotics for the tested microorganisms were also studied, proving that there was a synergistic interaction with vancomycin and ciprofloxacin and Staphylococcus epidermidis CECT 4183 and Escherichia coli CECT 101 bacteria, respectively.

UV PHOTOCATALYSIS AND METAL DOPED TITANIUM DIOXIDE: ELIMINATION OF E. COLI AND S. AUREUS IN WATER

Photocatalysis has been widely used for water disinfection and wastewater treatment. UV photocatalysis induced bacteria photocatalytic disinfection, focusing on mechanisms in bacteria inactivation. The problem with industrial wastewater is that it generally contains a high concentration of toxic or non-biodegradable pollutants. The application of photocatalysis is mainly focused on the removal of microorganisms. Metal-doped TiO2-based photocatalyst has a significant potential for the inactivation of harmful pathogens. In this research, the effect of different metal-doped on photocatalytic disinfection against Escherichia coli (E. coli) (gram-negative) and Staphylococcus aureus (S. aureus) (gram-positive) under UV light was investigated. TiO2 was used and doped with various types of metal such as copper (Cu), cobalt (Co), and iron (Fe). The experiments were run under UV light with 1 g/L of selected metal-doped for up to 3 hours. A series of photocatalytic disinfection on E. coli and S. aureus were conducted on water contamination with 500 mL of trypticase soy broth (TSB) and 5 ml of bacteria. These results show that the UV photocatalyst with Cu doped-TiO2 gives 99% of E. coli disinfection. While for S. aureus disinfection Co-doped-TiO2 gives 96% of removal bacteria after 3 hours of treatment. In conclusion, a metal-doped TiO2–based UV photocatalytic system is highly recommended for improving the water decontamination process.

The use of mucoadhesive oral patches containing epigallocatechin-3-gallate to treat periodontitis: an in vivo study

ObjectivesThe application of topical drugs such as mucoadhesive oral patches (MOPs) do not irritate the mucosa and are able to increase the permeability of drugs to oral tissue. Epigallocatechin-3-gallate (EGCG) is an active ingredient that exhibits significant antibacterial and anti-inflammatory effects. The purpose of this study was to analyze the therapeutic potential of a mucoadhesive oral patch containing EGCG (MOP-EGCG) in a model of periodontitis and investigate its effects on the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-kappa Β ligand (RANKL) and receptor activator of nuclear factor-κB (RANK). MethodsA model of periodontitis was induced in Rattus novergicus used Porphyromonas gingivalis by applying 0.03 ml of bacteria locally with 1 × 1010 colony-forming units (CFU) seven times at 2-day intervals in the central lower incisors. Periodontitis was then treated with MOP (control), a mucoadhesive oral patch containing doxycycline (MOP-doxy) or MOP-EGCG for 1 h/day for 21 days. On days 3, 5, 7, 14 and 21 after treatment, the central lower incisor was biopsied and analyzed by immunohistochemistry for RANK/RANKL and OPG expression in the gingiva tissue. ResultsMOP-EGCG extract significantly reduced the expression of RANKL and increased the expression of OPG and RANK (p < 0.05) when compared to the MOP-doxy and MOP groups. ConclusionMOP-EGCG extract reduced the expression of RANKL and increased the expression of OPG and RANK, thus suggesting that MOP-EGCG can inhibit the loss of alveolar bone in periodontitis.

Experimental investigation of self-repairing bio concrete in self compacting concrete

Concrete is a fundamental component of public infrastructure and a necessary building material. When exposed to tension, traditional concrete has a defect that causes it to crack. Concrete can withstand compressive pressures well, but not tensile forces. Concrete cracking is a serious problem in the building industry. The best method to conserve energy and safeguard the environment in terms of sustainable development is to make concrete structures more durable and easy to maintain. According to a recent study, by precipitating the chemical calcium carbonate through a process known as bio mineralization, Bacillus bacteria can be utilised to repair cracks in existing concrete structures. A revolutionary kind of concrete that may be put and crushed without the use of vibration and may flow under its own weight to entirely fill the form is concrete that self-compacts. The research clearly demonstrates the inquiry into various additions of bacteria to cement in the mix proportion of 5 to 60 ml of cement weight. The trial mix percentage is carried out for the varied features of workability, durability, and potency in order to reach the best bacterial concrete level. From the test and systematic examinations, the additional material for cement assumes an indispensable job in the durability and strength perspectives. By investigation the properties of cement, bacterial accomplished preferred execution over ordinary cement. The results show that 50 ml of bacteria is very supporting additional cement content. Overall, it satisfies in the aspect of potency, workability, and durable of concrete with bacterial products than ordinary conventional concrete.

In-vitro anti-bacterial effectiveness test of 2% chlorhexidine digluconate and ethanol extract of green meniran leaves (Phyllanthus niruri Linn) on the growth of Enterococcus faecalis bacterial colony

Background: Necrotic teeth with periapical lesions often experience root canal treatment failure. Enterococcus faecalis bacteria cause 85-90% of root canal infections. 2% Chlorhexidine digluconate (CHX) can eliminate Enterococcus faecalis bacteria but cannot dissolve necrotic tissue, while green meniran phytochemical compounds (Phyllantus niruri Linn) have anti-bacterial properties. This study aims to determine the effectiveness, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) between green meniran leaf extract with 2% chlorhexidine digluconate and meniran extract only against the growth of Enterococcus faecalis.Method: This is an in vitro experimental study with a broth microdilution method consisting of two treatment groups. The negative control contained BHIB media and 0.05 ml of bacteria; the positive control had 0.05 ml of bacteria with 2% chlorhexidine digluconate, the group one consisted of BHIB media, bacteria and various concentrations of meniran extract. In contrast, group two consisted of BHIB media, bacteria, various concentrations of green meniran with 2% chlorhexidine digluconate. Data were analyzed using the One Way Anova test with LSD test.Results: Compared with negative control, in group one, we found the MIC of meniran extract was 3.125% with 94% anti-bacterial power, and the MBC was 6.25% with no bacterial growth. In group 2, we found the MIC of meniran extract and the 2% chlorhexidine digluconate was 0.78% with 9.3% anti-bacterial power, while the MBC was 1.56%.Conclusion: The increasing concentration of meniran extract also increases the anti-bacterial effect. A combination of meniran extract and 2% chlorhexidine digluconate give better anti-bacterial effects than meniran extract only.

Development of a PCR-lateral flow assay for rapid detection of Yersinia pestis, the causative agent of plague

Plague is a zoonotic disease caused by Yersinia pestis, a Gram-negative, rod shaped coccobacillus, which is primarily found in rodents and can be transmitted to humans through flea bite. The disease has three major clinical forms bubonic (by flea bite), pneumonic (by respiratory droplets) and septicemic plague. Y. pestis is classified as a category ‘A’ agent by NIAID, USA due to its high mortality and easy person to person dissemination. The conventional diagnostic methods available for Y. pestis show cross-reactivity with other enteropathogenic bacteria making its detection difficult. There is a need to develop sensitive and specific molecular assay for accurate detection of Y. pestis. PCR is well suited molecular biology tool for rapid diagnosis of plague but after completion of thermal cycling steps, it requires additional time to analyze amplified product using agarose gel electrophoresis. In the present study, PCR assay coupled with lateral flow strips has been developed for rapid detection of Y. pestis. Lateral flow strips give an alternative to gel electrophoresis and permit easy and rapid detection of PCR products. The PCR was performed with 5′ 6-FAM and biotin tagged primers specific for Y. pestis, targeting yihN gene located on chromosome. The PCR product was analyzed using lateral flow strips which yielded result within 2-3 minutes. The analytical sensitivity of PCR-lateral flow (PCR-LF) assay was 1 pg genomic DNA of Y. pestis and 500 copies of target DNA sequence harboured in a recombinant plasmid. The assay could detect Y. pestis DNA extracted from spiked human blood samples containing ≥104 CFU per mL of bacteria. The assay was found to be specific and did not cross react with other closely related bacterial species. The developed assay was highly specific, sensitive and also did not require agarose gel electrophoresis for post amplification analysis.

Antibacterial activity and carbapenem re‐sensitizing ability of 1,10‐phenanthroline‐5,6‐dione and its metal complexes against KPC‐producingKlebsiella pneumoniaeclinical strains

Infections caused by KPC-producing Klebsiella pneumoniae (Kp-KPC) are associated with high mortality rates due to the increased number of resistant isolates and the scarcity of therapeutic options. This scenario reinforces the urgent need for new chemotherapeutics. Herein, we investigated the effects of 1,10-phenanthroline-5,6-dione (phendione) and its metal-based complexes, [Cu(phendione)3 ](ClO4 )2 .4H2 O (Cu-phendione) and [Ag(phendione)2 ]ClO4 (Ag-phendione), both alone and also combined with carbapenems (meropenem (MEM), and imipenem), against 46 clonally distinct clinical strains of Kp-KPC. All isolates were found to be multidrug resistant in accordance with their susceptibility patterns by disk diffusion method. Compounds geometric mean (GM)-MIC and GM-MBC values (μmoll-1 ), respectively, were: phendione, 42·06 and 71·27; Cu-phendione, 9·88 and 13·75; and Ag-phendione, 10·10 and 13·06. Higher synergism rates of MEM-containing combinations were observed by the checkerboard assay, particularly with the two metal complexes. Moreover, drug combinations were able to re-sensitize 87% of the phenotypically non-susceptible strains. Time-kill studies, with MEM plus Cu-phendione or Ag-phendione, indicated that combinations with 0·5× MIC of each agent produce synergistic effects after 9-12h. The MEM plus Ag-phendione eradicated about 106 CFU per ml of bacteria. These findings support the effectiveness of the re-sensitizing combinatorial approach and provide evidence that phendione-based compounds offer real promise in the fight against Kp-KPC infections.

Development of a set of three real-time loop-mediated isothermal amplification (LAMP) assays for detection of Bacillus anthracis, the causative agent of anthrax.

Bacillus anthracis, the causative agent of anthrax is a Gram-positive, non-motile, spore forming bacterium. Its spores can persist in soil and water for years and can also be aerosolized. A rapid, sensitive and specific method to detect B. anthracis is important for clinical management and preventing spread of anthrax. Loop-mediated isothermal amplification (LAMP) assay is a rapid technique that amplifies target DNA in isothermal conditions with high sensitivity and specificity. In this study, a LAMP assay set targeting a chromosomal and two plasmid markers was developed. The individual assays of the LAMP set targeting pXO1 plasmid (lef), pXO2 plasmid (capB), and chromosome (BA5345) sequences could detect 10, 250, and 100fg of genomic DNA and 10, 100, and 50 copies of the DNA targets harboured in recombinant plasmids, respectively. The lef and capB LAMP assays could detect ≥ 1 × 103CFU per mL of bacteria in spiked human blood samples, while BA5345 LAMP assay could detect ≥ 1 × 104CFU of bacteria per mL of spiked blood. The amplification was monitored in real-time by turbidimeter, and visual detection was also accomplished under normal and UV light after adding SYBR Green 1 dye on completion of the reaction. The assay set was found to be highly sensitive and did not cross-react with the closely related Bacillus spp. and other bacterial strains used in the study.

Evaluation of Antimicrobial Activity and Anti-Quorum Sensing of Rosmarinus Methanol Extract on Pseudomonas aeruginosa

Background: The increasing infections caused by resistant P. aeruginosa strains originate from hospitals. Therefore, many efforts are being made to find new herbal compounds as suitable substitutes for antibiotics. Objectives: The present study aimed to evaluate the antibacterial and anti-quorum activity of Rosmarinus methanol extract on P. aeruginosa. Methods: This experimental study was performed on standard and clinical strains of P. aeruginosa. The methanolic extract of Rosmarinus was prepared by the Soxhlet method, and the antimicrobial activity of the extract was evaluated by diffusion method in wells and microdilution. We examined the effect of this extract on the antibiofilm activity, protease, and pyocyanin production of P. aeruginosa in order to investigate the anti-quorum sensing activity of methanolic extract of Rosmarinus. Via SPSS 17, we managed to conduct the statistical analysis. Results: The mean diameter of growth inhibition zone obtained from methanolic extract of rosemary at a concentration of 500 mg/ml on Pseudomonas aeruginosa was 18.5 mm, and the minimum inhibitory concentration of methanolic extract of rosemary was 125 mg / ml for bacteria. Extract at concentrations higher than 62.5 mg /ml prevented biofilm formation, protease, and the pyocyanin production of P. aeruginosa. Conclusions: The results of the present study can be a valuable report on their useful role in infection control because the methanol extracts of Rosmarinus had suitable antibacterial and anti-quorum sensing activity. It is suggested that more studies be conducted on the identification of antimicrobials as a suitable alternative for antibiotics in the treatment of diseases.

The effect of addition of bacterium Pseudomonas aeruginosa on biodegradation of methyl orange dye by brown-rot fungus Gloeophyllum trabeum

The methyl orange (MO), one of common textile dyes from azo groups, has negative impact in human life and the environment. Therefore, many attemps have been devoted to find the most effective method for MO degradation. Brown-rot fungus Gloeophyllum trabeum has identified as the biodegradable agent of MO, but its efficiency is still low, and it requires a long incubation time. In this work, the biodegradable performance of brown-rot fungus Gloeophyllum trabeum was investigated for MO degradation in the presence of bacterium Pseudomonas aeruginosa with various volumes (2-10 mL, 1 mL = 5.05 x 1012 Colony Forming Unit (CFU)). The addition of 10 mL of bacteria into G. trabeum culture showed the maximum degradation of 88.67% in potato dextrose broth (PDB) medium for the 7-day incubation. The identified metabolites were 4-((4-(dimethyliminio) cyclohexa-2.5-dien-1-ylidenehydrazinyl) phenolate (C14H15N3O, compound 1), 4-((4-iminiocyclohexa-2.5-dien-1-ylidene) hydrazinyl) benzenesulfonate (C12H10N3O3S, compound 2), 4-((hidroksi-4-iminioyclohexa-2.5-dien-1-ylidene) hydrazinyl) benzenesulfonate (C12H10N3O4S, compound 3), 4-((4-(dimethyliminio) hydroxy-cyclohexa-2.5-dien-1-ylidene) hydrazinyl) methoxy benzenesulfonate (C15H16N3O5S, compound 4), and 4-((4-(dimethyliminio) dihydroxy-cyclohexa-2.5-dien-1-ylidene) hydrazinyl) dimethoxy benzenesulfonate (C16H18N3O7S, compound 5). Based on the identification of metabolic products, the mixed cultures transformed MO via three pathways: (1) desulfonylation, (2) demethylation, and (3) hydroxylation. These results indicate that P. aeruginosa can enhance MO biodecolorization by G. trabeum.

English

The phytochemical screening and antimicrobial activities of the methanol extract of Garcinia kola fruit mesocarp were investigated against four bacteria and two fungi in the study. The extract was investigated for the presence of phytochemicals using standard phytochemical screening methods. The results revealed the presence of flavonoids, tannins, alkaloids, terpenoids, cardiac glycosides, and reducing sugar. The percentage of alkaloids, flavonoids and tannins are 24, 27.5 and 4%, respectively. The extract exhibited effective antimicrobial activity against the test organisms. The minimum inhibitory concentration ranged from 275.4 to 691 &micro;/ml for bacteria and 346.7 to 318.2 &micro;/ml for fungi respectively compared to chloramphenicol and ketoconazole [standards drugs] which exhibited a minimum inhibitory concentrations (MIC) of 14.31-31.62 and 2.66-2.99 &micro;g/ml. These findings suggest that the fruit mesocarp of G. kola could be a potential source of compounds used against microorganism infection. Key words: Phytochemical screening, antimicrobial activity, Garcinia kola heckle fruit extract.

Development and application of a triplex-PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus from pigs.

A triplex-PCR assay was developed and evaluated for rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) recovered from various biological samples of pig. Three sets of primers were designed to target mecA, 16S rRNA and nuc genes of MRSA. The specific amplification generated three bands on agarose gel, with sizes 280bp for mecA, 654bp for 16S rRNA and 481bp for nuc, respectively. A potential advantage of the PCR assay is its sensitivity with a detection limit of 102 CFU per ml of bacteria. In all, 79 MRSA isolates recovered from various samples of pigs were subjected to the amplification by the triplex-PCR assay and all the isolates yielded three bands corresponding to the three genes under this study. No false-positive amplification was observed, indicating the high specificity of the developed triplex-PCR assay. This assay will be a useful and powerful method for differentiation of MRSA from methicillin-sensitive S. aureus, coagulase-negative methicillin-resistant staphylococci and coagulase-negative methicillin-sensitive staphylococci.

Complex interactions and different possible pathways among functional components of the aquatic microbial world in Farasan Archipelago, Southern Red Sea, Saudi Arabia.

This work aims to outline the dynamics of trophic links between the three main microbial components (bacteria, nanoflagellates, and ciliates) of the Farasan Archipelago in order to establish a baseline for future research in this area. The Farasan Archipelago lies along the southwestern coast of the Saudi Arabia, southern Red Sea between 16°20′–17°10′N and 41°30′–42°30′E and had been declared as marine and terrestrial reserve by the year 1996. Three different sites were chosen for this study, with each site visited bimonthly for 18 months from September 2016 to February 2018. Bacteria, nanoflagellates and ciliates were enumerated in order to explore the complex interactions between the main microbial categories in sea waters of the Farasan Archipelago. High abundances were recorded during the present study for bacteria (8.7 × 106 bacteria ml−1), nanoflagellates (3.7 × 104 TNAN ml−1) and ciliates (40.4 ciliates ml−1). The paper discusses the various potential pathways controlling the complex interactions between these microbial groups in this part of the southern Red Sea. It is concluded that a linear trophic chain consisting of bacteria; heterotrophic nanoflagellates; filter feeding ciliates is a major route by which the production of bacteria is transferred to the higher consuming levels, thereby confirming the high importance of t bottom-up control (food supply), alongside top-down control (predation) in regulating bacterial abundances in the Farasan Archipelago. During the present investigation, each nanoflagellate ingested between 11 and 87 bacteria in one hour, while each ciliate consumed between 20 and 185 nanoflagellates every hour. These calculated grazing rates of protistan eukaryotes confirmed the role of heterotrophic nanoflagellates as the main consumers of bacteria, and the role of ciliates as the major control for the heterotrophic nanoflagellate population dynamics, and thus the top predators within the microbial plankton assemblage in the Farasan Archipelago.

477. Characterization of Extended-Spectrum Β-Lactamase (ESBL) Producing Gram-negative (GN) Urinary Tract Infections (UTI) in Pediatric Patients

BackgroundThere has been an increase in antimicrobial resistance among GN pathogens, not only in adults, but also pediatrics. UTIs are common in pediatrics; however, reports of pediatric UTI with ESBL producing GN are limited.MethodsAll urine cultures positive for ESBL producing GN from 5/1/18 to December 31/18 were retrospectively reviewed. Proven infection (PI) defined as ≥50,000 colony-forming units (CFU)/mL of bacteria plus pyuria or positive leukocyte esterase for catheterized or clean catch specimens. Relapsed infection defined as same pathogen cultured within 30 days of infection. Abnormal urinary tract systems or functions (AUTS) include neurogenic bladder, structural anomalies, or intermittent catheterization.ResultsA total of 107 urine cultures for ESBL producing GN, from 85 patients, were included. Majority of specimens [78/107 (73%)] were obtained from the ED or outpatient clinics. 43% of specimens were from patients with AUTS. E. coli was the majority (95%) of ESBL isolates. 57% of ESBL producing GNs were susceptible to amoxicillin/clavulanate (AC) or trimethoprim/sulfamethoxazole (TMP/SMX). 88% were nitrofurantoin susceptible. Only 1 isolate was meropenem resistant. Antibiotics (ABX) were prescribed for UTI in 67/107 episodes. However, only 52 episodes were PI. Of these, 38 were empirically treated with oral ABX and 29 with intravenous ABX. The most commonly prescribed empiric ABX was oral cephalexin (25/67, 37%.) Ineffective empiric ABX for UTI was very common, 83% (43/52). Of these, 5/43 never received effective therapy and none had relapse. Most common duration of ABX was 10 days (range 5–17 days.) 43% (23/52) of PI were treated with oral AC or TMP/SMX. 15% (8/52) of PI were treated with nitrofurantoin. 12% of PI were treated with a once-daily aminoglycoside. Only 6% of PI were treated with a carbapenem.ConclusionMany ESBL UTI isolates remain susceptible to oral ABX. Although small numbers, patients treated with ineffective ABX did not return with relapsed infection. Non-carbapenem ABX are a reasonable option to minimize selective pressure or unnecessary use. Empiric narrow-spectrum antibiotic therapy may still be appropriate.Disclosures All authors: No reported disclosures.

The Potential Microbe Agent to Degrade Naphtalene and Phenanthrene in Dumai Oil Sludge : A Growth Response Test

This study aims to find the most appropriate indigenous bacteria as Naphthalene and Phenanthrene degrading agents carried out in the growth response test. This research is very important to find the best bacterial agent, which in the future can reduce the impacts of oil pollution, as well as from the presence of oil sludgeBacterial cultures added in the media as much as 5% (v / v), which had previously been measured OD660nm = 0.5. The growth response test was carried out by growing 20 mL of bacteria in AMS media which was added with PAH substrate, naphthalene or Phenanthrene in various concentrations: 200 ppm, 500 ppm, 800 ppm, and 1000 ppm. In the naphthalene substrate with 24-hour incubation, the best treatment was in isolates A with a concentration of 200 ppm. In the phenanthrene substrate 24 hours incubation, the best treatment was in isolate A at 200 ppm, and at 48 hours incubation. Bacterial isolates F in 24-hour incubation increased growth in all treatments and controls. The bacterial E isolate on the phenanthrene substrate at 24-hour incubation has increased growth, which occurs until the incubation time is 48 hours, both in the control and phenanthrene substrate. E Isolate is tolerant of increasing substrate concentrations up to 1000 ppm, both naphthalene and phenanthrene and has the best growth ability. It can be concluded that isolate E has the best growth ability and is tolerant of increasing substrate concentrations up to 1000 ppm. E isolates were designated as the best isolates of naphthalene and phenanthrene degradation. Keywords: Dumai, Growth Response, Naphthalene, Phenanthrene

Biocontrol of saprolegniosis in rainbow trout (Oncorhynchus mykiss Walbaum) using two bacterial isolates (LE89 and LE141) of Pseudomonas fluorescens.

The probiotic activity of 15 bacterial isolates that inhibit Saprolegnia parasitica in vitro was tested for the biocontrol of saprolegniosis in rainbow trout (Oncorhynchus mykiss Walbaum), adding the bacteria to tank water for 14days at a concentration of 106 bacteria ml-1 water. Pseudomonas fluorescens LE89 and Pseudomonas fluorescens LE141 were effective in controlling experimental infection with S.parasitica since of the fish treated with LE89, 24.5%±16.27% (p<0.05) became infected, as did 42.8%±8.41% (p<0.05) of those treated with LE141. Given their protective effect when administered in water, their effect was also studied when administered in feed before and after experimental infection. Both bacterial isolates survived low pH levels and the action of bile, grew in skin and intestinal mucus, were resistant to several antibiotics and survived in feed; however, neither of the two isolates prevented S.parasitica infection when administered in feed.

Simple, Fast And Highly Sensitive Detection Of Gram-Negative Bacteria By A Novel Electrical Biosensor.

This work presents a rapid, low-cost, highly sensitive and specific capacitive sensor for detection of Gram negative bacteria in a field setting. Recognition of Gramnegative bacteria is based on specific detection of lipopolysaccharides (LPS) by LPS-specific aptamer probe immobilized on electrode sensors. An inhomogeneous AC electric field is applied on sensor electrodes and induces positive dielectrophoresis that attracts LPS particles to the sensor electrodes for rapid detection. The same AC signal is also used to detect the binding reactions occurred on the sensor surface. The AC signal was optimized, and the binding between LPS and the specific aptamer was demonstrated. The detection limit reaches as low as 4.9 fg/mL for free LPS molecules and 53 #/mL of bacteria within a 30s' response time, meeting the needs of onsite bacteria detection.

Resistance patterns of gram negative bacteria in urinary tract infections and efficacy of empirical treatment in noncomplicated cases: Retrospective cohort study of 2180 women

Aim: Community and hospital acquired urinary tract infections (UTI) are the most common bacterial infections in all age groups. In this study, the women diagnosed UTI, which complicated and uncomplicated, were referred to outpatient clinics between 2011 and 2015 were selected. The suitability of empirical antimicrobial therapy prescribed with resistance patterns of Gram negative bacteria isolated from these patients was investigated. Methods: UTI complaining and urine culture ≥10⁵ cfu / ml of bacteria that women aged 18-65 were comprised the study group. HIS (Hospital Information System Software) was scanned for these patients and uncomplicated and complicated UTI distinction was made according to the criteria set by Infectious Diseases Society of America (IDSA, 2016). Of the 2180 patients studied, 836 were complicated and 896 were noncomplicated. Identification of Gram negative isolates in urine culture; Conventional methods and Matrix-Assisted Laser Desorption and Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS), (Biotyper, Bruker, Germany) systems were used. The antimicrobial susceptibilities of the isolated strains from 2011 to 2014 were determined according to the Clinical Laboratory Standards Institute (CLSI) and the isolated strains in 2015 were determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Results: The distribution of 2180 female patients (18 to 65 years old) was urology polyclinic (68%), family medicine, infectious disease and physical medicine and rehabilitation polyclinics (19.1%), and emergency medicine polyclinic (12.6%). E. coli (84%), K. pneumonia / oxytoca (7%) and Enterobacter spp (2.6%) were the most frequently detected agents in the uncomplicated UTIs, while complicated UTI E. coli (91%), K. pneumonia / oxytoca (5.7%) and P. aeruginosa (1%) were found to be the first, second and third in the patients. Quinolones were prescribed 18.2%, phosphomycin 16.7%, nitrofurantoin 15.6%, nitrofurantoin and phosphomycin combined 16.3%, second generation oral cephalosporins 9.6% and third generation oral cephalosporins 10.7%. Resistance to quinolones, the most commonly prescribed antibiotic, was found in 19% of E. coli, 21% of Klebsiella spp., 13% of Enterobacter spp. and 9% of Proteus spp. Conclusion: When these prescriptions were compared with the results of antimicrobial susceptibility, it was observed that 38 (14%) were incompatible with the sensitivity results. It was found that 42% of cefuroxime prescriptions, 28% of quinolone prescriptions and 17% of ceftriaxone prescriptions were incompatible with the antibiogram results.

INHIBITION OF BACTERIA ISOLATED FROM NINH THUAN GRAPES BY ORGANIC ACIDS

Ninh Thuan grapes are famous specialty of Vietnam. After harvesting, they are very susceptible to damage if not preserved in time. This study aimed to find the minimal inhibitory concentration and minimal bactericidal concentrations of organic acids, such as lactic acid, citric acid, and ascorbic acid towards seven bacteria previously isolated from Ninh thuan grapes (Empedobacter brevis, Citrobacter sp. Enterobacterium ludwigii, Bacillus cereus, Flavobacterium sp., Pseudomonas oryzihabitans and Bacillus thuringiensis) in order to apply in pretreatment of grapes prior to storage. The Minimal Inhibitory Concentration (MIC) was determined by the binary dilution method. 0.1 ml of each dilution of test acids with initial concentration of 3 % was mixed with 0.1 ml of bacteria (c.a. 5.105 CFU/ml), in 96-culturing-well plate. Innoculated plate was incubated for 24 hours at temperature of 37 °C. Optical density was measured at 620 nm wavelength by a Microplate reader device. For Minimal Bactericidal Concentration (MBC) determination, 0.1 ml of bacteria (c.a.5.105 CFU/ml) was mixed with 0.4 ml liquid medium of Tryptone Glucose Agar (TGA) and of 0.5 ml acid at above concentrations, culturing within 24 hours at temperature of 37 °C. After 24 hours, they were dropped onto TGA agar plates, and cultured for 24 hours at 37 °C. The results showed that, the MIC and MBC of citric acid toward Empedobacter brevis were 0.12 mg/ml and 0.12 mg/ml; Citrobacter sp. were 0.9 mg/ml and 3.8 mg/ml; Enterobacterium ludwigii were 0.45 mg/ml and 1.9 mg/ml; Bacillus cereus were 0.9 mg/ml and 0.9 mg/ml; Flavobacterium sp. were 0.12 mg/ml and 0.45 mg/ml; Pseudomonas oryzihabitans were 0.12 mg/ml and 0.45 mg/ml and Bacillus thuringiensis were 0.12 mg/ml and 0.9 mg/ml, respectively. Similarly, MIC and MBC of lactic acid toward: Empedobacter brevis were 0.12 mg/ml and 0.23 mg/ml;Citrobacter sp. were 0.9 mg/ml and 1.9 mg/ml; Enterobacterium ludwigii were 0.45 mg/ml and 0.9 mg/ml; Bacillus cereus were 0.23 mg/ml and 0.45 mg/ml; Flavobacterium sp. were 0.12 mg/ml and 1.9 mg/ml; Pseudomonas oryzihabitans were 0.23 mg/ml and 1.9 mg/ml and Bacillus thuringiensis were 0.12 mg/ml and 1.9 mg/ml, respectively. Ascorbic acid was found to be inefficient for use as antimicrobial agent against isolated bacteria. The above results suggested that citric and lactic acids could be used at maximal concentrations of 3.8 mg/ml and 1.9 mg/ml, respectively to suppress bacteria from grapes. This finding would contribute to develop method for pretreatment of grapes in fresh grape preservation techniques.

English

This study assessed the seasonal variation of microbiological, physicochemical and heavy metal analysis of water samples from Ayao Stream around a hospital waste dumpsite. Four samples were collected downstream and analyzed for microbial count, coliforms, pH, electrical conductivity, BOD5, alkalinity, total dissolved solids, water hardness, sulphate, nitrate, chloride and phosphate using standard method. Heavy metals (Fe, Mn, Cu, Zn, Cd and Pb) in the water were determined by Atomic Absorption Spectrophotometry. Results obtained showed that the stream was greatly polluted with microbial and coliform count of 2.1 × 104 to 3.6 × 105 CFU/ml, 1.8 × 102 to 8.0 × 102 CFU/ml, and 1.1 × 103 to > 1.1 × 103 CFU/100 ml for bacteria, fungi and coliform count, respectively during both wet and dry season. The bacteria recovered from the samples included the antibiotic resistant Pseudomonas and Klebsiella. The mean values of pH (8.0 to 9.1) and BOD5 (17.2 to 26.3) were obtained during dry and wet season, respectively and were found to be beyond the acceptable limit in drinking water. This result established a relationship between the BOD5 and microbial load which indicate organic pollution through runoff input from the dumpsite into the stream. The concentration of Mn, Fe, Cu, Pb and Cd especially during rainy season was found to exceed the stipulated limit in drinking water. These metals could be bio accumulated to toxic level in aquatic organisms and end up in human through the food chain. This study shows that Ayao Stream is greatly polluted and unfit for domestic uses. Key words: Dumpsite, heavy metal, microbial load, coliforms, hospital waste.