Modern approaches for detection of volatile organic compounds in metabolic studies focusing on pathogenic bacteria:Current state of the art

Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.

Antiseptic Efficacy of A Soap Made from Biosurfactants Isolated from Bacillus and Lactobacillus against Pathogenic Bacteria

The aim of our study was to use a biosurfactant produced by Bacillus and Lactobacillus isolates as an antiseptic in the formulation of local soap. A total of 60 isolates were characterized by microbiological techniques (30 Bacillus and 30 Lactobacillus) and the ability to produce biosurfactants was demonstrated by a hydrocarbon emulsification index (E24). The emulsification indexes (E24) varied from 9% to 100% for Bacillus and from 33% to 100% for Lactobacillus as well. The antagonistic assay showed that biosurfactants were able to inhibit the formation of biofilms and growth of pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Salmonella typhirium, Shigella boydii and Proteus mirabilis. The biosurfactant consortium (BioC) from Bacillus consortium and from Lactobacillus was able to inhibit biofilm formation and the pathogens growth. The BioC was stable to alkaline pH and the temperatures stability of Biosurfactant was ranging from 50°C to 90°C. The soap was made by the cold saponification process using one biosurfactant consortium formulated. This soap has a pH of 10 and showed good cleaning power and good foam stability. Similarly, the soap showed good antiseptic power and disinfection power against all pathogens tested. Handwashing is critical to preventing disease transmission. The persistence of pathogens in waste water was evaluated. The BioS produced showed good disinfection power against all pathogens tested. The valor of reduction on the hands and in the waste water was significantly more than compared to the control soaps used. This soap could be used in the prevention, fighting, and treatment of bacterial and viral infections.

Distribution of pathogenic bacteria and antimicrobial sensitivity of eye infections in Suzhou

AIM:To investigate the types of bacteria in patients with eye infections in Suzhou and their drug resistance to commonly used antibacterial drugs.METHODS:The clinical data of 155 patients were retrospectively collected in this study,and the pathogenic bacteria species and drug resistance of each pathogenic bacteria were analyzed.RESULTS:Among the 155 patients(age from 12 to 87 years old,with an average age of 57,99 males and 56 females)with eye infections(160 eyes:74 in the left eye,76 in the right eye and 5 in both eyes,all of which were exogenous),71(45.81%)strains were gram-positive bacteria,23(14.84%)strains were gram-negative bacteria and 61(39.35%)strains were fungi.Gram-positive bacteria were highly resistant to penicillin and erythromycin(78.87%and 46.48%respectively),but least resistant to vancomycin at 0.Gram-negative bacteria were highly resistant to cefoxitin and compound sulfamethoxazole(100%and 95.65%respectively),but least resistant to meropenem at 0.Comparison of the resistance of gram-positive and gram-negative bacteria to some drugs revealed statistically significant differences(P<0.05)in the resistance of both to cefoxitin,cotrimoxazole,levofloxacin,cefuroxime,ceftriaxone and ceftazidime,and both had higher rates of resistance to gram-negative bacteria than to gram-positive bacteria.The distribution of bacterial infection strains showed that Staphylococcus epidermidis was the most common strain in the conjunctiva,cornea,aqueous humor or vitreous body and other eye parts.Besides,Fusarium and Pseudomonas aeruginosa were also among the most common strains of conjunctival and corneal infections.CONCLUSION:Gram-positive bacteria are the dominant bacteria in eye infections,followed by gram-negative bacteria and fungi.Considering the resistance of gramnegative bacteria to multiple drugs,monitoring of bacteria should be strengthened in eye bacterial infections for effective prevention and control to reduce complications caused by eye infections.

Resistance of Microbial Community of Artemisia annua L.to Pathogenic Fungi

[Objectives]This paper was to figure out whether the dominant bacterial community has the role and effect of bacterial community and its defense mechanism against potential pathogenic fungi in Artemisia annua,and thus establish a systematic model of bacteria-fungus-plant.[Methods]Fifty-eight strains of bacteria and one strain of pathogenic fungi,Globisporangium ultimatum,were used for the experiments.These 58 bacterial strains were assembled into a bacterial community,and the bacteria with abundance in the top 1%were reassembled into a dominant bacterial community as measured by 16S rDNA.[Results]The growth of A.annua seedlings inoculated with bacterial communities and pathogenic fungi or dominant bacterial communities and pathogenic fungi was significantly better than that of A.annua seedlings inoculated with pathogenic fungi during in vitro confrontation,which was evident in both enzymatic and non-enzymatic antioxidant assays.[Conclusions]The results suggest that the dominant bacterial community has a crucial role as a representative core microbial community of synthetic bacterial community,which can protect plants by interfering with the growth of phytopathogenic fungi mediated by chemical signals,and can be used as the main synthetic community of biocides to achieve the effect of biocontrol.

Drug Sensitive Test on Main Pathogenic Bacteria of Cow Recessiveness Mastitis Using Traditional Chinese Medicine Preparation “Zengrujianniusan”

According to the theory of Chinese veterinary medicine and characteristics of Chinese herbal medicine, four different preparations of compound Chinese medicine ＂Zengrujianniusan＂ were composed, and the prepared water decoction was used to carry on the bacteriostatic test on main pathogens of cow recessiveness mastitis. The results showed that the four different prescriptions of water decoction all had antibacterial effects. The prescription 3 was sensitive to Staphylococcus aureus and Streptococcus agalactiae, while the other three prescriptions showed high sensitivity, and the prescription 3 had the strongest bacteriostatic effects.

Antibacterial efficacy of the seed extracts of Melia azedarach against some hospital isolated human pathogenic bacterial strains

Objective:To investigate the antibacterial potential of the polar and non-polar extracts of the seeds of Melia azedarach(M.azedarach) L.(Meliaceae) against eighteen hospital isolated human pathogenic bacterial strains.Methods:Petrol,benzene,ethyl acetate,methanol,and aqueous extracts at five different concentrations(1,2,5,10 and 15 mg/mL) were evaluated.Disk diffusion method was followed to evaluate the antibacterial efficacy.Results:All extracts of the seeds demonstrated significant antibacterial activity against tested pathogens.Among all extracts,ethyl acetate extract revealed the highest inhibition comparatively.The present study also favored the traditional uses reported earlier.Conclusions:Results of this study strongly confirm that the seed extracts of M.azedarach could be effective antibiotics,both in controlling gram-positive and gram-negative human pathogenic infections.

Survival of pathogenic bacteria in compost with special reference to Escherichia coli

Application of compost in agricultural practice could potentially cause contamination of foodstuffs with pathogenic bacteria such as Escherichia coli O157：H7 （E. Coli O157）. We investigated pathogenic bacteria in compost collected from the compost facilities, and evaluated the survival of E. coli K12 and O157 in laboratory experiments. Out of 19 compost product samples, coliform bacteria and salmonella were detected in 7 and 3 samples respectively. The number of coliform bacteria was 1.8 × 10^2 to 2.5 × 10^6 CFU/g dw and that of salmonella was 4.2 × 10^1 to 6.0 × 10^3 CFU/g dw. Moreover. coliform bacteria, fecal coliform, E. coli and salmonella were detected during composting at 54℃ to 67℃. The results indicated that moisture content was a very important factor to the heat sensitivity of pathogenic bacteria in compost, E. coli in compost of high moisture content was more sensitive than that in compost of low moisture content, cells harvested in logarithmic phase was more sensitive than these in stationary phase, and E. coli K12 was more sensitive than E. coli O157. Based on the D values, the lethal time of E. coli K12 and 0157 from 10^8 to 10^0 CFU/g dw were 16.3 and 28.8 min, respectively, at 60℃ in compost with 40% moisture content. However, some E. coli cells survived in composting process at 54℃ to 67℃. Water potential（low moisture content） and physiological aspects of bacteria（stationary phase） could explain only in part of the prolonged survival of E. coli in compost, and there should be some other factors that are conducive to bacterial survial in compost.

Fucoxanthin Isolated from Undaria pinnatifida Can Interact with Escherichia coli and lactobacilli in the Intestine and Inhibit the Growth of Pathogenic Bacteria

Fucoxanthin is a xanthophyll-type carotenoid that provides many benefits to human health. However, the mechanism by which fucoxanthin interacts with microbes and inhibits pathogenic bacteria is unknown. In this study, we investigated the effects of fucoxanthin isolated from the edible seaweed Undaria pinnatifida on pathogenic bacteria Escherichia coli and lactobacilli both in vitro and in vivo. Fucoxanthin strongly inhibited the growth of Gram-positive pathogenic bacteria but was less effective against Gram-negative bacteria. Fucoxanthin extracted from the crude mixture had a recovery rate of 93.38% and a purity of 82.70%, which were higher than those of fucoxanthin extracted using a previous method. Fucoxanthin also promoted the growth of intestinal mi- crobes in mice. Fucoxanthinol, a metabolite of fucoxanthin, was generated in the culture media. Fucoxanthin can be deacetylated into fucoxanthinol not only by conventional digestive enzymes in the digestive tract, but also by E. coli and lactobacilli in the intestine. These results indicate that fucoxanthin interacts with and influences E. coli and lactobacilli in the intestine. Therefore, fucoxanthin isolated from Undaria pinnatifida possibly can be applied in human health maintenance.

In vitro antibacterial potential of some Vitex species against human pathogenic bacteria

Objective:To study the antibacterial activity of the leaf methanol extracts of five different species of Vitex namely,Vilex altissima(V.allissima),Vitex diversifolia(V.diversifolia),Vitex negundo(V.negundo),Vitex peduncularis(V.peduncularis) and Vitex trifolia(V.trifolia). Methods:Antibacterial assay was carried out by using disc diffusion method,determination of minimum inhibitory concentrations(MIC) and minimum bactericidal concentrations(MBC) against five strains of Gram-positive and seven strains of Gram-negative human pathogenic bacterial strains.Results:The results of antibacterial activity of Vitex species showed that the extracts possessed a broad spectrum of antibacterial activity.The V.peduncularis possessed the highest activity against all the microorganisms screened.It produced a zone of inhibition ranged between (11.000±0.577) and(22.670±0.667) mm and the MIC values were from 62.5 to I 000.0μg/mL and the MBC values were from 125.0 to 2 000.0μg/mL.Conclusions:Based on the present study, V.peduncularis is recommended for the isolation of antibacterial molecule responsible for the activity against the tested human pathogenic bacterial strains.

Antibacterial activity of leaves extracts of Trifolium alexandrinum Linn,against pathogenic bacteria causing tropical diseases

Objective:To investigate antibacterial potential of Trifolium alexandrinum(T.alexandrinum) Linn,against seven gram positive and eleven gram negative hospital isolated human pathogenic bacterial strains responsible for many tropical diseases.Methods:Non-polar and polar extracts of the leaves of T.alexandrinum i.e.,hexane,dichloromethane(DCM),ethyl acetate(EtOAc), methanol(MeOH) and aqueous(AQ) extracts at five different concentrations(1,2,5,10 and 15 mg/ mL) were prepared to evaluate their antibacterial value.NCCL standards were strictly followed to perform antimicrobial disc susceptibility test using disc diffusion method.Results:Polar extracts demonstrated significant antibacterial activity against tested pathogens.EtOAc and MeOH extracts showed maximum antibacterial activity with higher inhibition zone and were found effective against seventeen of the tested pathogens.While AQ plant extract inhibited the growth of sixteen of the test strains.EtOAc and MeOH plant extracts inhibited the growth of all seven gram positive and ten of the gram negative bacterial strains.Conclusions:The present study strongly confirms the effectiveness of crude leaves extracts against tested human pathogenic bacterial strains causing several tropical diseases.Since Egyptian clover is used as a fodder plant,it could be helpful in controlling various infectious diseases associated with cattle as well.

Studies on the edwardsiellosis and characterization of pathogenic bacteria from diseased flounder (Paralichthys olivaceus L.) and turbot (Scophthalmus maximus L.)

Edwardsiellosis of flounder and turbot occurring in different mariculture farms during 2001～ 2004 was examined, including the conditions of disease occurrence, clinical signs and pathological changes. The results showed that all diseased fishes expressed bacterial septicaemia. A total of 148 strains were identified using a combination of traditional physiological and biochemical tests and partial 16S rRNA gene analysis. In addition, the mole fraction G ＋ C ratio of the DNA of representative strain of isolates and serum homology were detected, and pathogenicity tests of isolates were conducted by experimental infection. The results revealed that 148 strains were identified as E. tarda of genus Edwardsiella, all the isolates are of serologic similarity, and have strong pathogenicity to flounder and turbot.

Distribution and drug resistance of pathogenic bacteria isolated from cancer hospital in 2013

Objective： To understand distribution and drug resistance of pathogenic bacteria from a specialized cancer hospital in 2013 in order to provide a basis for rational clinical antimicrobial agents. Methods： Pathogenic bacteria identification and drug sensitivity tests were performed with a VITEK 2 compact automatic identification system and data were analyzed using WHONET5.6 software.Results： Of the 1,378 strains tested, 980 were Gram-negative bacilli, accounting for 71.1%, in which Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa were the dominant strains. We found 328 Gram-positive coccus, accounting for 23.8%, in which the amount of Staphylococcus aureus was the highest. We identified 46 fungi, accounting for 4.1%. According to the departmental distribution within the hospital, the surgical departments isolated the major strains, accounting for 49.7%. According to disease types, lung cancer, intestinal cancer and esophagus cancer were the top three, accounting for 20.9%, 17.3% and 14.2%, respectively. No strains were resistant to imipenem, ertapenem or vancomycin.Conclusions： Pathogenic bacteria isolated from the specialized cancer hospital have different resistance rates compared to commonly used antimicrobial agents; therefore antimicrobial agents to reduce the morbidity and mortality of infections should be used.

Functional identification of phenazine biosynthesis genes in plant pathogenic bacteria Pseudomonas syringae pv. tomato and Xanthomonas oryzae pv. oryzae

Phenazines are secondary metabolites with broad spectrum antibiotic activity and thus show high potential in biological control of pathogens. In this study, we identified phenazine biosynthesis （phz） genes in two genome-completed plant pathogenic bacteria Pseudomonas syringae pv. tomato （Pst） DC3000 and Xanthomonas oryzae pv. oryzae （Xoo） PXO99A. Unlike the phz genes in typical phenazine-producing pseudomonads, phz homologs in Pst DC3000 and Xoo PXO99A consisted of phzC/D/E/F/G and phzC/E1/E2/F/G, respectively, and the both were not organized into an operon. Detection experiments demonstrated that phenazine-l-carboxylic acid （PCA） of Pst DC3000 accumulated to 13.4 IJg L-1, while that of Xoo PXO99A was almost undetectable. Moreover, Pst DC3000 was resistant to 1 mg mL-1 PCA, while Xoo PXO99A was sensitive to 50 IJg mL ~ PCA. Furthermore, mutation of phzF blocked the PCA production and significantly reduced the pathogenicity of Pst DC3000 in tomato, while the complementary strains restored these phenotypes. These results revealed that Pst DC3000 produces low level of and is resistant to phenazines and thus is unable to be biologically controlled by phenazines. Additionally, phz-mediated PCA production is required for full pathogenicity of Pst DC3000. To our knowledge, this is the first report of PCA production and its function in pathogenicity of a plant pathogenic P. syringae strain.

Fluorescent antibiotics for real-time tracking of pathogenic bacteria

The harm of pathogenic bacteria to humans has promoted extensive research on physiological processes of pathogens,such as the mechanism of bacterial infection,antibiotic mode of action,and bacterial antimicrobial resistance.Most of these processes can be better investigated by timely tracking of fluorophore-derived antibiotics in living cells.In this paper,we will review the recent development of fluorescent antibiotics featuring the conjugation with various fluorophores,and focus on their applications in fluorescent imaging and real-time detection for various physiological processes of bacteria in vivo.

Bio-control of Some Food-Borne Pathogenic Bacteria by Bacteriophage

In recent years, researchers tended to bring new alternative to biological protective systems used in conservation of food and production of safe food. Use of bacteriophage against to pathogen bacteria in food was the most hopeful system in these methods about bio-control. Controls of bacteriophage for each pathogen species and subspecies and determination of phage-host originality are important because efficient bio-control was achieved. Researches concentrated on some food-borne pathogen bacteria such as E. coli O157：H7, Campylobacter, Salmonella and Listeria. In a consequence of these studies made as in vitro and in vivo, first commercial production of phage which will be used in foods was made in Netherlands. Also, it has been informed that use of phage is cost-efficient alternative as compared with other preservatives. This review, discussed application of bacteriophages as bio-control agents in food and advantages and disadvantages about uses of bacteriophages by taking into account antimicrobial characteristics of them.

Synergistic Effect of Combined Antibiotics against Some Selected Multidrug Resistant Human Pathogenic Bacteria Isolated from Poultry Droppings in Akure, Nigeria

Antibiotic resistant bacteria pass between humans, between animals and between humans and animals in both directions, the use of antibiotics in poultry has contributed to multiple antibiotic resistant in pathogenic bacteria and use of two antibiotics might prevent the emergence of resistance to either. In this study, synergistic effect of combined antibiotics against multidrug resistant human pathogenic bacterial isolates from poultry droppings in Akure, Nigeria was examined. Collection of samples, isolation and identification of bacteria were carried out using standard microbiological method, antibiotic sensitivity test was performed by disc diffusion method and zone of inhibition was used to interpret the sensitivity test as resistant, susceptible or intermediate while combined effects of two antibiotics were investigated by macrobroth dilution and checkerboard assay methods while the synergetic effects of combined antibiotics were calculated using Fractional Inhibitory Concentration (FIC) and percentage synergistic interaction was calculated. All the ten (10) species of bacterial isolates were multidrug resistant and are less resistant to ofloxacin. The highest percentage synergistic interactions observed were Ofloxacin + Amoxicillin (90%), Ciprofloxacin + Amoxicillin (90%), Tetracycline + Amoxicillin (70%), Tetracycline + Augmentin (80%), Cotrimoxazol + Amoxicillin (50%), Cotrimoxazol + Augmentin (70%), Chloramphenicol + Amoxicillin (70%) and Chloramphenicol + Augmentin (80%). Poultry droppings is a potential source of human pathogenic bacteria, high frequency of multiple antibiotic resistance bacteria observed in this study is of great treat to man as this may cause the treatment of infection caused by these bacteria to be difficult. Combination of beta-lactam antibiotic with fluoroqunolones, tetracycline, Chloramphenicol and Cotrimoxazole was synergetic and this will reduce dose related toxicity and prevent resistance to single antibiotic.

Pathogenic Bacteria Associated with Different Public Environmental Sites in Mecca City

Background: The hygiene of environmental surfaces from shopping, ATM machines, telephones and computers and miscellaneous sites play role in spreading fecal and total coliform bacteria as well as pathogenic bacteria. Objectives: This study addresses the contaminated common sites by pathogenic or potentially pathogenic bacteria in Mecca, SA. Materials and Methods: A total 648 swab samples were collected and analyzed for presence or absence of pathogenic bacteria. Results: Of the total samples 422 were negative bacterial count (71%) and 226 (29%) were positive. All collected samples (100%) of glass windows in the fish markets were bacterial counted;most dominated was Bacillus spp. (n = 97) and the highest population of species was Enterococcus faecalis (n = 40) and E. coli (n = 16). Conclusion: Some public sites were very contaminated with different types of fecal coliform group of bacteria such as shopping cart handles, inner surfaces and child seats in supermarkets, and the glass windows in the fish market. Acinetobacter haemolyticus and other hemolytic bacteria were isolated from more than site.

Antibacterial activity of plant extracts in different solvents against pathogenic bacteria: An in vitro experiment

Objective:To assess the antibacterial activity of 5 selected plants against 4 pathogenic bacteria.Methods:Three solvents with different polarities were used to extract antimicrobial agents from the plants via maceration technique.The agar-disc diffusion technique was adopted to primarily screen antibacterial activities.Broth-dilution assay was employed to determine the minimum inhibitory concentration(MIC)and the minimum bactericidal concentration(MBC).Results:Among all extracts,the ethanol extract of Piper betle Linn showed the highest antibacterial activity against Gram-positive and the negative bacteria.MIC and MBC of the ethanol extract of Piper betle Linn against Salmonella typhimurium were the same(1?562.50 mg/L);while it showed the highest MIC and MBC against Pseudomonas aeruginosa of 6?250 mg/L and 12?500 mg/L,respectively.Conclusions:Salmonella typhimurium is the most susceptible bacteria while Pseudomonas aeruginosa is the most resistant bacteria towards the ethanol extract of Piper betle Linn.Piper betle possesses compounds with potential antibacterial activity and might be useful as an alternative to control infectious diseases.

Species Identification of Mealie Meal Spoilage Organisms and Pathogenic Bacteria from Selected Food Stores in Lusaka District of Zambia

Background: Mealie Meal is one of the by-products of maize from dry milling. It constitutes more significant part of the daily diet of growing population of the Lusaka District of Zambia. However, reported cases of a cholera outbreak in October 2017-May 2018 were attributed to water contamination in the households of Lusaka. Hitherto there is no previous study or documented data for gastroenteritis caused by microbial contamination from food stores. Aim: The main objective of the study was to carry out species identification of Mealie meal spoilage organisms and pathogenic bacteria from selected food stores in Lusaka district from September 2019-March 2020. Crosssectional survey was conducted for food spoilage organisms and pathogenic bacteria of packaged maize meal flour from a selected food store. The number of packaged Mealie meal samples from selected food stores included in the study was 143 samples. Samples were obtained by a simple stratified random selection from food stores in Lusaka District. Thus Mealie Meal samples bought from Street food vendors were 96 (67%), Shops—30 (21%), Malls—17 (11.9%). Subsequently isolation by spread and pour plate methods, and species identification of microbial contamination by Cell Culture processes coupled to microbial morphological and biochemical characterization was performed. Microsoft Office Excel (version 2007) Spreadsheet was employed for the categorical data analysis and summarized graphical presentation of data. Laboratory findings revealed: Spoilage organisms—Aspergillum species, Mucor Species, Candida Species, Clostridium Species and Bacillus Species;Pathogenic Bacteria Species—Clostridium perfringens, Staphylococcus aureus, Clostridium tetani, Bacillus, Escherichia coli, Pseudomonas aeruginosa and Yesinia pestis. It can be established from the laboratory results earlier mentioned that the food poisoning outbreak could evolve from food stores in Lusaka district apart from water contamination.

Rapid label-free SERS detection of foodborne pathogenic bacteria based on hafnium ditelluride-Au nanocomposites

Two-dimensional(2D)nanomaterials have captured an increasing attention in biophotonics owing to their excellent optical features.Herein,2D hafnium ditelluride(HfTe_(2)),a new member of transition metal tellurides,is exploited to support gold nanoparticles fabricating HfTe_(2)-Au nanocomposites.The nanohybrids can serve as novel 2D surface-enhanced Raman scattering(SERS)substrate for the label-free detection of analyte with high sensitivity and reproducibility.Chemical mechanism originated from HfTe_(2) nanosheets and the electromagnetic enhancement induced by the hot spots on the nano-hybrids may largely contribute to the superior SERS effect of HfTe_(2)-Au nanocomposites.Finally,HfTe_(2)-Au nanocomposites are utilized for the label-free SERS analysis of foodborne pathogenic bac-teria,which realize the rapid and ultrasensitive Raman test of Escherichia coli,Listeria mono-cytogenes,Staphylococcus aureus and Salmonella with the limit of detection of 10 CFU/mL and the maximum Raman enhancement factor up to 1.7×10^(8).Combined with principal component analysis,HfTe_(2)-Au-based SERS analysis also completes the bacterial classification without extra treatment.