Growth Of Gram-negative Bacteria Research Articles

Chlamydomonas reinhardtii-derived triple BmKbpp distorts membrane integrity for inhibiting bacterial growth

Antibiotic abuses cause pathogen resistance to conventional antibiotics, threating public health globally. Antimicrobial peptides were considered as substitutes for antibiotic because of their broaden and rapid antibacterial activity. BmKbpp extracted from the Chinese scorpion Mesobuthus martensii Karsch inhibits the growth of gram-negative bacteria and fungi efficiently, while its efficacy for inhibiting the growth of the gram-positive Staphylococcus aureus was limited. Besides, how BmKbpp inhibits bacterial growth remains elusive thus far. In this study, a C-terminal hemagglutinin (HA) and 6×His (HA-6×His) tagged BmKbpp of three repeats (3×BmKbpp) was expressed in Chlamydomonas reinhardtii. The recombinant 3×BmKbpp-HA-6×His exhibited antibacterial activity against both gram-positive and gram-negative bacteria with a minimum inhibitory concentration between 20⁓200 µg/ml. The minimum bactericidal concentration ranged from 1 × MIC to 3 × MIC for 3×BmKbpp-HA-6×His. 3×BmKbpp-HA-6×His exhibited a good thermostability and resisted on pH shock and digestion of certain proteinases. It also displayed low cytotoxicity and hemolysis as tested on cell lines including HEK293, Vero, MDCK, and BHK-21. In addition, 3×BmKbpp-HA-6×His inhibits bacterial growth by effectively distorting bacterial cell membrane. Thus, C. reinhardtii-derived 3×BmKbpp-HA-6×His effectively inhibits bacterial growth, making it a promising antimicrobial peptide.

Влияние Lactobacillus acidophilus на рост биопленок в подсырной сыворотке

The modeling of the biofilms formation in cheese whey on glass under static conditions including with Lactobacillus acidophilus was carried out. Biofilm development in cheese whey is faster than in its ultrafiltration permeate. The basis of the three-dimensional structure of a mature biofilm is made up of representatives of the genera included in the group of sanitary indicative microorganisms. Yeasts are involved in all stages of biofilm formation. L. acidophilus cells of the «BK-Uglich-AV» starter actively integrate into the biofilm structure, inhibiting the growth of gram-negative bacteria and contributing to the destruction of the exopolysaccharide layer, but without affecting yeast. The data obtained can be used both for the development of biofilm control methods in the dairy industry and for biotechnological purposes.

THE CONTINUING MENACE OF EXTENDED SPECTRUM BETA LACTAMASE (ESBLS) - A CENTRE BASED STUDY

Abstract:
 Objective: To determine the occurrence of Extended-spectrum β-lactamase (ESBL) producing gram negative bacteria (GNB) and their sensitivity patterns in a tertiary care hospital.
 Methods: In this cross-sectional study, conducted in the Microbiology section of Pathology lab, in a tertiary care hospital Lahore, various specimens such as blood, body fluids, urine, and pus were included during a period starting from October 2020 till September 2021. The samples having growth of gram negative bacteria were processed further for determination of ESBL production. After isolation, antimicrobial susceptibility pattern was determined for each isolate.
 Results: GNB were isolated from 130 samples, among those 46 (35.4%) were labelled as ESBL. The commonest ESBL producing bacteria was E. coli, followed by pseudomonas aeruginosa found in 17.39% samples. In E. Coli, Imipenem (IPM) showed highest sensitivity of 84.8%, other sensitive drugs were Amikacin (AK), gentamicin (CN), and Tazobactam-piperacillin(TZP). For Pseudomonas aeruginosa, Imipenem and Tazobactam-piperacillin showed sensitivity of 75%, AK and CN were 50% sensitive. Against Klebsiella pneumoniae , IPM was 100% sensitive, AK and TZP were 85.7% sensitive. IPM, CN, and AK were 100% sensitive against Morganella morganii. AK and CN were 100% sensitive against Citrobacter species.
 Conclusion: It was concluded that, there was significant prevalence of ESBL producing strains amongst Gram negative bacterial infections. E. Coli and Pseudomonas aeruginosa were the commonest ESBL producers. IPM, AK, and TZP were sensitive against majority of the ESBL producing GNB.

Study of in vitro antioxidant and antibacterial potential of different tea clones

BackgroundCamellia sinensis (L.) O. Kuntze (tea) belongs to the family of Theaceae and is one of the most popular beverages. According to traditional Chinese medicine, its phytochemicals have the ability to cure various diseases of the liver, heart, spleen, and lungs. This study was done to explore the phytochemical potentiality of leaf extracts from different tea clones with special emphasis on their antioxidant, total phenol, flavonoid, and antibacterial activity. MethodsThe leaves were extracted in methanol for various qualitative, and quantitative tests like antioxidant assay, total phenolic content, flavonoid content etc. ResultsThe result of this study delivers comparative data about the biochemical properties of various tea clones which will further help in future studies. Leaves extract of tea clones like TV-9, TV-26, CP-1 and Phoobsering-312 showed promising antioxidant activity. Leaves extract of TV-9, TV-23, TV-26 and CP-1 has shown an inhibitory effect on the growth of Gram-negative bacteria Escherichia coli. Among the clones, Phoobsering-312 was found to be the most prominent tea clone as it exhibited total phenolic content, and antioxidant properties along with very significant antibacterial activity against Escherichia coli and Bacillus subtilis. ConclusionThis study showed the Darjeeling Garden clone (Phobsering-312) could be selected as an ideal clone for cultivation in the study area. This is to sustain the phytochemical quality of tea and gain health benefits, as the quality of manufactured tea is reflected in all aspects of the green harvest.

The prevalence of Carbapenem Resistance Gram negative pathogens in a Tertiary Teaching Hospital in Jordan

BackgroundWith the absence of new antimicrobial drugs being developed to replace those facing resistance, bacterial resistance continues to grow. Despite previous studies conducted in various countries, there is a lack of comprehensive local reporting on the occurrence of carbapenem resistance among gram-negative bacteria.ObjectiveThis study aims to identify the prevalence of carbapenem-resistant gram-negative bacterial isolates.MethodA retrospective cross-sectional study was conducted at an academic hospital in Jordan over an eight-month period, spanning from November 2021 to June 2022. The study involved screening electronic medical records to identify patients with clinical cultures showing the growth of Gram-negative bacteria. Antimicrobial susceptibility results of the Gram-negative isolates were recorded.ResultsA total of 1,043 isolated Gram-negative bacteria were analyzed for carbapenem susceptibility. Among the species tested, the most common carbapenem-resistant bacteria were Acinetobacter baumannii (153/164, 93.3%), followed by Klebsiella pneumonia (184/311, 59.2%), and Pseudomonas aeruginosa (67/160, 41.9%). The least commonly isolated species resistant to carbapenem were Escherichia coli (25/361, 6.9%) and Proteus mirabilis (1/30, 3.3%). None of Serratia marcescens or Proteus vulgaris isolates were resistant to carbapenem (0%). Overall, the prevalence of carbapenem-resistance gram-negative isolates was 41.2% (430 out of 1,043).ConclusionThis study provides population-specific data that are crucial for guiding empirical antimicrobial treatment decisions not only within the participating hospital but also in other nearby healthcare facilities. The results underscore the urgent need for coordinated efforts to address antibiotic resistance in Jordan. Comprehensive measures such as strict infection control methods, annual nationwide surveillance programs, and effective antimicrobial stewardship programs at the national level are imperative to reduce the overuse of broad-spectrum antibiotics.

Thymosin beta-4 participate in antibacterial immunity and wound healing in black tiger shrimp, Penaeus monodon

Thymosin beta-4 (Tβ4) is a ubiquitous protein with multiple and diverse intracellular and extracellular functions in vertebrates, which play fundamental roles in innate immune against pathogens and wound healing. In this study, the full-length cDNA of Tβ4 was cloned from Penaeus monodon (designated as PmTβ4), using the technology of rapid amplification of cDNA ends (RACE). The cDNA of PmTβ4 was 1361 bp with an open reading frame (ORF) of 501 bp, which encoding a polypeptide of 166 amino acid. The Quantitative Real-time PCR (qRT-PCR) analysis results showed that PmTβ4 was ubiquitously expressed in all the tested shrimp tissues, with the highest expression level was detected in the hemolymph, while the lowest expression level in the muscle. The expression level of PmTβ4 was significantly up-regulated in hepatopancreas after challenged by Vibrio parahaemolyticus, Vibrio harveyi and Staphylococcus aureus. In vitro antimicrobial test showed that the recombinant protein of PmTβ4 (rPmTβ4) had broad-spectrum of antimicrobial activity, which could inhibit both the growth of gram-negative bacteria and gram-positive bacteria, including Vibrio vulnificus, V. parahaemolyticus, Streptococcus agalactiae, S. aureus and Aeromonas hydrophila. Moreover, rPmTβ4 had a certain binding ability to different bacteria, and this binding ability exhibits a strong dose-dependent effect. In vivo, PmTβ4 could facilitate external bacterial clearance in shrimp, and have beneficial to shrimp survival post V. parahaemolyticus infection. Furthermore, wound-healing assay was carried out to study the role of PmTβ4 in the process of wound healing. The results showed that the PmTβ4 expression was significantly up-regulated by injury treatment, and exerted positive effects to promote wound healing. In addition, PmTβ4 can significantly increase the expression level of superoxide dismutase (SOD) and Catalase (CAT) after injury treatment in shrimp, which would involve in scavenging reactive oxygen species (ROS) caused by the wound. In conclusion, these results indicated that PmTβ4 may play important roles in antibacterial immunity and wound healing in Penaeus monodon.

Assessment of chemical compositions and antibacterial activity of the essential oil of Mentha piperita in response to salicylic acid

Mentha piperita, as a species of the mint family, is used in various medical, cosmetic, industrial and culinary products. The effect of different concentrations of salicylic acid (SA) (0. 0.5, 1 mM) on phytochemical activity and antimicrobial potential of Mentha piperita essential oil against six human pathogenic bacteria (Streptococcus agalactiae, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Listeria monocytogenes) were investigated. According to the results to prevent the growth of L. monocytogenes and S. agalactiae, Gram-positive bacteria, peppermint, essential oil treatment with 1 mM salicylic acid is suggested. But to prevent the growth of Gram-negative bacteria P. aeruginosa and E. coli, peppermint essential oil of control plants is proposed. These results showed that salicylic acid elicitor changed the type and amount of peppermint essential oil compounds. Probably, salicylic acid elicitor improved antimicrobial properties of peppermint essential oil with a change in essential oil components. The inhibitory activity of essential oil depends on the type of microorganism, the concentration of essential oil and the concentration and time of salicylic acid treatment.

Physical properties of multifunctional TM-doped ZnO nanorods and their photocatalytic and anti-bacterial activities.

Dilute magnetic semiconductor Zn1-xCuxO (x = 0, 1.5, 3.0, and 4.5%) nanorods were prepared by hydrothermal method. The impact of dopant concentration on the physical properties was investigated along with the anti-bacterial and photocatalytic activities. Synthesis of ZnO nanorods was confirmed by the characteristic band at 380nm in UV-Visible spectra of the synthesized samples. A red shift in absorbance spectra was observed from 380 to 465nm with an increase in dopant concentration. The hexagonal wurtzite geometry and rod-like morphology of Cu-doped ZnO nanorods having an average size of 29nm were confirmed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. An increase in the crystallinity of the material was observed with an increase in the dopant (Cu) ratio without any alteration in geometry. EDX analysis was used to confirm the purity of samples. FTIR spectra were recorded to explore the functional group present in samples. The hysteresis loop drawn by a vibrating-sample magnetometer (VSM) was utilized to analyze the ferromagnetic behavior. As-synthesized pure and Cu-ZnO nanorods were evaluated for their photocatalytic behavior for the photodegradation of methyl orange (MO) dye. Zn1 - xCuxO with x = 4.5%, pH 3, and catalyst dosage of 0.5g has shown the maximum efficiency. Results elucidated > 81% degradation of MO dye with a rate constant (k) value of - 1.930 × 10-2min-1 in just 90min of exposure to a visible light source. ZnO nanorods have also exhibited anti-bacterial potential against gram-positive and gram-negative strains of bacteria. However, smaller size nanorods were found more effective to suppress the growth of gram-negative bacteria. A slight decrease (11%) in catalytic potential was observed in the 5th cycle during recycling and reuse experiments.

Prevalence and pattern of multidrug resistant Gram-negative bacilli isolated from patients in the intensive care unit of a tertiary care hospital in Coastal Karnataka

Infections due to Gram negative bacilli (GNB) are the leading cause of mortality in ICU patients and are associated with higher morbidity rates, longer hospital stays and increased healthcare expenditures. Infections due to GNB in the ICU is about 2 to 5 times higher than in the general in-patient hospital population. This study aims to look at the prevalence of multi drug resistant gram-negative bacilli and proportion of ESBL producers in the MICU and to determine susceptibility patterns of GNB isolated, to various antibiotics. A total of 616 samples were collected from 396 patients admitted to the MICU during the 4-month study period. After the samples were inoculated and identified, the gram-negative isolates were subjected to Antibiotic susceptibility testing using Kirby Bauer Disc Diffusion technique with 17 different antibiotic disks. Strains showing decreased sensitivity to Ceftazidime/Cefotaxime were screened for ESBL production. Among the 616 samples tested, 149 (24.2%) samples showed growth of Gram-negative bacteria exclusively. Total number of GNB’s isolated were 173 due to some samples showing polymicrobial growth. The most common GNB found was (27.7%) which was followed by Klebsiella pneumonia at 26.0% and Acinetobacter baumannii at 18.5%. 64.2% of all GNB’s were Multi Drug Resistant which included 75% , 71.1% Klebsiella pneumoniae and 84.4% Acinetobacter baumannii. The study shows that the MDR GNB infections are on the rise in the ICU with GNBs being highly resistant to many previously effective first line antibiotics like Penicillins, newer Cephalosporins and Fluoroquinolones with susceptibility rates below 25% and even 0% for earlier generation Cephalosporins.

Enhancing effect of chitosan nanoparticles on the immune efficacy of Bordetella bronchiseptica outer membrane vesicles

The outer membrane vesicle (OMV) of bacteria is a bilayer membrane vesicle with a diameter of about 10–300 nm that is secreted during the growth of Gram-negative bacteria. OMV is considered as a high-quality vaccine candidate antigen because of its natural immunogenicity and non-replicability. Although the excellent antigenicity of OMV has been widely confirmed, its instability and heterogeneity greatly affect its immune effect. Many studies have demonstrated that in combination with nanoparticles can enhance the stability of OMV. In this study, OMVs were used to coat chitosan nanoparticles (CNPs) and obtain a stable OMV vaccine. The characteristics, including morphology, hydrodynamic size, and zeta potential were evaluated. The immune protection of CNP-OMV and anti-infection efficacy were examined and compared in vivo and in vitro. The results showed that the CNP-OMV were homogenous with a size of 139 nm and a stable core–shell structure. And CNP-OMV could significantly increase the cell proliferation, phagocytosis and TNF-α, IL-6 and IL-10 secretion of RAW264.7 in vitro. In vivo, CNP-OMV could significantly increase the levels of anti-Bb and OMV IgG antibodies. Levels of blood lymphocyte, and Th1 (IFN-γ, IL-12), Th2 (IL-4, IL-5), and Th17 (IL-17, TNF-α) type cytokines in the serum were all significantly increased. At the same time, CNP-OMV could significantly reduce the bacterial invading the lungs of challenged rabbits. And CNP-OMV could largely protect the lungs from injury. The above results showed that CNP-OMV had a good immune efficacy and could resist the infection of Bordetella bronchiseptica. This study provided a scientific basis for the development of novel effective and safe vaccine against Bordetella bronchiseptica, and also provided a new idea for the development of new bacterial vaccine.

Growth of Gram-Negative Bacteria in Antiseptics, Disinfectants and Hand Hygiene Products in Two Tertiary Care Hospitals in West Africa-A Cross-Sectional Survey.

Antiseptics, disinfectants, and hand hygiene products can act as reservoirs of Gram-negative bacteria causing healthcare-associated infections. This problem is rarely documented in low- and middle-income countries, particularly in sub-Saharan Africa. In a cross-sectional survey, we assessed the bacterial contamination of antiseptics, disinfectants, and hand hygiene products in two university hospitals in Burkina Faso and Benin. During ward visits and staff interviews, in-use products were cultured for the presence of Gram-negative bacteria. The growth of Gram-negative bacteria was absent or rare in alcohol-based products, povidone iodine, and Dakin solution. Contamination was highest (73.9% (51/69)) for liquid soap products (versus antiseptic/disinfectants (4.5%, 7/157) (p < 0.0001)), mostly used in high-risk areas and associated with high total bacterial counts (>10,000 colony-forming units/mL). Contaminating flora (105 isolates) included Enterobacterales and the Vibrio non-cholerae/Aeromonas group (17.1%) and non-fermentative Gram-negative rods (82.8%). Multidrug resistance was present among 9/16 Enterobacterales (Klebsiella and Enterobacter spp.) and 3/12 Acinetobacter spp., including carbapenem resistance (Acinetobacter baumannii: NDM, Pseudomonas stutzeri: VIM). The risk factors for contamination included the type of product (cleaning grade and in-house prepared liquid soap), use of recycled disposable containers and soft drink bottles, absence of labeling, topping-up of containers, dilution with tap water (pharmacy and ward), and poor-quality management (procurement, stock management, expiry dates, and period after opening).

Extended Spectrum B-Lactamase (ESBL) and Metallo B-Lactamase (MBL) Production in Gram-Negative Bacteria isolated from Urinary Tract Infection Patients.

Background: The rate of infections caused by Morganella species is reported to be affected by difficulties in their isolation. Enterobacter, species, Citrobacter freundii, Serratia marcescens, and Morganella morganii are the major pathogens involved in hospital acquired infections. All of them are extensively reported in the infections of urinary tract, respiratory tract, cutaneous disorders, catheter associated infections and infections of the central nervous system.Objective: To investigate the frequency of ESBL producing bacteria in Urinary Tract Infection. Material and Methods: A cross-sectional study of 200 urine samples was collected from the outdoor patient departments of Khyber Teaching Hospital Peshawar through consecutive sampling technique during April, 2019 to June 2019. The urine samples were collected and then cultured on selective media i.e., Cysteine Lactose Electrolyte Deficient Agar (CLED) and on MacConkey agar plates. Isolates were identified by conventional morphological and biochemical tests while antibiotic susceptibility was analyzed by “Agar disc diffusion method” using different antibiotics and their zone of inhibition was measured. Results: Total 200 samples processed, 125 (62.5%) isolates, including 67 (53.6%) females, tested positive for the growth of Gram-negative bacteria. Among the identified species, 76 (60.8%) isolates produced ESBLs, with Escherichia coli accounting for 32.6%, Enterobacter for 23.2%, and Morganella species for 12.0%. Moreover, 77 (61.6%) of the isolates were found to be MBL positive, with 30 (24.0%) of them being E. coli, 28 (22.4%) being Enterobacter, and 19 (15.2%) being Morganella spp. The isolates formed a zone of inhibition like a clover leaf and demonstrated a sensitivity of 85 (68%) to antibiotics in the carbapenem class, such as imipenem and meropenem. Cefoparazone/Sulbactam 80 (64.0%), Ofloxacin 79 (63.2%), and Amikacin 78 (62.4%) were the next three antibiotics with high sensitivity. Ampicillin 106 (84.8%) showed the highest resistance, followed by Nitrofurantoin 84 (67.2%) and Ceftriaxone 79 (63.2%), in that order. Conclusion: The study indicated that ESBL-producing bacteria were present frequently among UTI patients. Most of the isolates exhibited strong carbapenem class antibiotic sensitivity. The findings of this study may contribute to the formulation of tactics to lower the incidence of ESBL-producing UTI.Keywords: Antibiotics resistance, Gram Negative bacteria, Plasmid-mediated enzymes, UTI.

Bacteremia in Severe Mastitis of Dairy Cows.

The aim of this cross-sectional study was to investigate the occurrence of bacteremia in severe mastitis cases of dairy cows. Milk and corresponding blood samples of 77 cases of severe mastitis were bacteriologically examined. All samples (milk and blood) were incubated aerobically and anaerobically to also investigate the role of obligate anaerobic microorganisms in addition to aerobic microorganisms in severe mastitis. Bacteremia occurred if identical bacterial strains were isolated from milk and blood samples of the same case. In addition, pathogen shedding was examined, and the data of animals and weather were collected to determine associated factors for the occurrence of bacteremia in severe mastitis. If Gram-negative bacteria were detected in milk samples, a Limulus test (detection of endotoxins) was also performed for corresponding blood samples without the growth of Gram-negative bacteria. In 74 cases (96.1%), microbial growth was detected in aerobically incubated milk samples. The most-frequently isolated bacteria in milk samples were Escherichia (E.) coli (48.9%), Streptococcus (S.) spp. (18.1%), and Klebsiella (K.) spp. (16%). Obligatory anaerobic microorganisms were not isolated. In 72 cases (93.5%) of the aerobically examined blood samples, microbial growth was detected. The most-frequently isolated pathogens in blood samples were non-aureus Staphylococci (NaS) (40.6%) and Bacillus spp. (12.3%). The Limulus test was positive for 60.5% of cases, which means a detection of endotoxins in most blood samples without the growth of Gram-negative bacteria. Bacteremia was confirmed in 12 cases (15.5%) for K. pneumoniae (5/12), E. coli (4/12), S. dysgalactiae (2/12), and S. uberis (1/12). The mortality rate (deceased or culled) was 66.6% for cases with bacteremia and 34.1% for cases without bacteremia. High pathogen shedding and high humidity were associated with the occurrence of bacteremia in severe mastitis.

Some like it hot: Variable impact of a tailpiece heating device on different gram-negative bacteria

Background: Transmission of multidrug-resistant bacteria to patients from colonized hospital sink drains has prompted attempts to interrupt transmission through a variety of interventions directed at the wastewater environment. We previously found that use of a heating device designed to disrupt biofilm formation between the P trap and the sink drain, which is the major point of dispersal of bacteria to the patient-care environment, was associated with reduced risk of detectable gram-negative organisms on hospital sink drains. However, there was no observed effect on some important pathogens, including Pseudomonas aeruginosa and Stenotrophomonas maltophilia. We hypothesized that heating to a higher temperature would provide additional efficacy in preventing drain colonization. Methods: As part of a previous randomized study, 54 tailpiece heaters were installed in 3 intensive care units in an academic hospital and 2 acute-care units in an associated regional hospital; half of these devices were shams (ie, no heat). The devices were programmed to heat for 1 hour every fourth hour. Prior to this study, a device update increased the heating temperature (during the previous study the median heated temperature was 65.9°C). Sink drains and P traps were sampled monthly. Samples were assessed for semiquantitative growth of gram-negative bacteria on MacConkey agar, looking especially for P. aeruginosa and S. maltophilia. Frontline personnel were blinded to device assignment. Results: The mean heated temperature reached was 74.4°C. Based on proportional odds logistic regression (wherein the odds ratio reflects the likelihood of a given sample falling in a lower microbiologic burden level versus the levels above it), the heating device was associated with increased likelihood of lower microbiologic burden at the drain level for general growth on MacConkey agar (OR, 2.47; 95% CI, 1.11–5.51) and for growth of S. maltophilia (OR, 5.39; 95% CI, 2.20–13.18). The device did not have an effect on burden of Enterobacterales (OR, 1.38; 95% CI, 0.58–3.24). For P. aeruginosa, there was a trend toward decreased likelihood of lower microbiologic burden (OR, 0.41; 95% CI, 0.18–1.07) that did not reach statistical significance at the drain level, and the heating device was associated with decreased likelihood of lower microbiologic burden of P. aeruginosa at the P-trap level (OR, 0.20; 95% CI, 0.10–0.39). Conclusions: Heat disruption of biofilm between the P trap and sink may be a promising strategy for prevention of hospital sink drain colonization; however, the impact is variable across different bacterial species. Further understanding of the dynamics of the microbiome within wastewater is needed.Disclosures: None

Identification and Analysis of Antimicrobial Activities from a Model Moss Ceratodon purpureus.

The emergence of bacterial drug resistance is often viewed as the next great health crisis of our time. While more antimicrobial agents are urgently needed, very few new antibiotics are currently in the production pipeline. Here, we aim to identify and characterize novel antimicrobial natural products from a model dioicous moss, Ceratodon purpureus. We collected secreted moss exudate fractions from two C. purpureus strains, male R40 and female GG1. Exudates from the female C. purpureus strain GG1 did not exhibit inhibitory activity against any tested bacteria. However, exudates from the male moss strain R40 exhibited strong inhibitory properties against several species of Gram-positive bacteria, including Staphylococcus aureus and Enterococcus faecium, though they did not inhibit the growth of Gram-negative bacteria. Antibacterial activity levels in C. purpureus R40 exudates significantly increased over four weeks of moss cultivation in liquid culture. Size fractionation experiments indicated that the secreted bioactive compounds have a relatively low molecular weight of less than 1 kDa. Additionally, the R40 exudate compounds are thermostable and not sensitive to proteinase K treatment. Overall, our results suggest that the bioactive compounds present in C. purpureus R40 exudates can potentially add new options for treating infections caused by antibiotic-resistant Gram-positive bacteria.

Comparison of systemic trimethoprim-sulfadimethoxine treatment and intrauterine ozone application as possible therapies for bacterial endometritis in equine practice.

Bacterial endometritis is one of the major problems in equine reproduction and usually treated with antimicrobial drugs. The study aimed to compare the effects of intrauterine ozone application and systemic antibiotic treatment (trimethoprim-sulfadimethoxine) on intrauterine bacterial growth and possible side effects on the endometrium in a clinical setting. Mares (n = 30) with signs of endometritis (positive uterine bacterial culture and cytological findings) were assigned randomly to different treatments: intrauterine insufflation of an ozone-air-mix (240 ml, 80 μg ozone/ml) twice at a 48 h-interval (Ozone; n = 10), systemic antibiotic therapy with trimethoprim-sulfadimethoxine (30 mg/kg, p.o., twice daily) for 5 days (TMS; n = 10), or intrauterine insufflation of air (240 ml, sterile-filtered) twice at a 48 h-interval (air; n = 10). Endometrial biopsy for histological examination was obtained before the treatment. Histological examination revealed no differences among groups. A control examination, including transrectal ultrasound, bacterial culture, cytological evaluation, and biopsy, was performed 7 days after the last treatment. Overall bacterial growth was reduced in every group after the treatment (p < 0.05), irrespective of the therapy [Ozone: 4/9 (positive culture after treatment/number of mares), TMS: 3/10 and Air: 6/10; p > 0.05]. However, Ozone and TMS (p < 0.05) were more effective in reducing growth of gram-negative bacteria as compared to Air (p > 0.05). No effects on the number of polymorphonuclear granulocytes (cytology) were observed (p > 0.05). In conclusion, trimethoprim-sulfadimethoxine and intrauterine ozone insufflation are safe treatment options for bacterial endometritis in mares but the efficacy of both treatments in reducing bacterial growth did not result in a complete absence of intrauterine bacterial growth.

Gossypol acetate: A natural polyphenol derivative with antimicrobial activities against the essential cell division protein FtsZ.

Antimicrobial resistance has attracted worldwide attention and remains an urgent issue to resolve. Discovery of novel compounds is regarded as one way to circumvent the development of resistance and increase the available treatment options. Gossypol is a natural polyphenolic aldehyde, and it has attracted increasing attention as a possible antibacterial drug. In this paper, we studied the antimicrobial properties (minimum inhibitory concentrations) of gossypol acetate against both Gram-positive and Gram-negative bacteria strains and dig up targets of gossypol acetate using in vitro assays, including studying its effects on functions (GTPase activity and polymerization) of Filamenting temperature sensitive mutant Z (FtsZ) and its interactions with FtsZ using isothermal titration calorimetry (ITC), and in vivo assays, including visualization of cell morphologies and proteins localizations using a microscope. Lastly, Bacterial membrane permeability changes were studied, and the cytotoxicity of gossypol acetate was determined. We also estimated the interactions of gossypol acetate with the promising target. We found that gossypol acetate can inhibit the growth of Gram-positive bacteria such as the model organism Bacillus subtilis and the pathogen Staphylococcus aureus [both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA)]. In addition, gossypol acetate can also inhibit the growth of Gram-negative bacteria when the outer membrane is permeabilized by Polymyxin B nonapeptide (PMBN). Using a cell biological approach, we show that gossypol acetate affects cell division in bacteria by interfering with the assembly of the cell division FtsZ ring. Biochemical analysis shows that the GTPase activity of FtsZ was inhibited and polymerization of FtsZ was enhanced in vitro, consistent with the block to cell division in the bacteria tested. The binding mode of gossypol acetate in FtsZ was modeled using molecular docking and provides an understanding of the compound mode of action. The results point to gossypol (S2303) as a promising antimicrobial compound that inhibits cell division by affecting FtsZ polymerization and has potential to be developed into an effective antimicrobial drug by chemical modification to minimize its cytotoxic effects in eukaryotic cells that were identified in this work.

Antioxidant and Antimicrobial Properties of Ethanolic Extract of Lemon Verbena

Background and Objectives: Chemical preservatives are commonly used to prevent food from quick spoiling and oxidizing. Despite their effect in increasing shelf life of foods, these compounds can have side effects. Residues of chemical compounds in foods increase microbial resistance. This study aims to investigate the antioxidant and antimicrobial properties of lemon verbena (Lippia citriodora L.) ethanolic extract against some gram-positive and gram-negative bacteria. Methods: In this experimental study, The soaking method and ethanol solvent was used for extraction. Antioxidant activities of different concentrations of extract were assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity test and compared with butylated hydroxyanisole (BHA) as a synthetic antioxidant. Antimicrobial effect of extract on Staphylococcus aureus, Listeria innocua, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium was determined by disk diffusion and well diffusion methods and measuring minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Experimental data were analyzed in SPSS software, version 20 using analysis of variance and the mean values were compared using Duncan’s multiple range test. Results: The amounts of phenols and flavonoids in the ethanolic extract of were 96.47±0.35 mg of gallic acid/g of extract and 31.07±0.42 mg of quercetin/g of extract, respectively. The half-maximal inhibitory concentration of lemon verbena extract was 11.79±0.76 μg/mL, while it was 10.16±0.29 μg/mL for BHA. In both disk diffusion and well diffusion methods, with the increase of the concentration of extract, the inhibition zone diameter increased. The ethanolic extract of lemon verbena at the concentration of 12.5 mg/mL had no inhibitory effect on gram-negative bacteria growth. In both methods, the extract had the greatest effect on S. aureus. The MIC of ethanolic extract ranged from 8 to 128 mg/mL, depending on the type of bacteria (gram-positive or gram-negative). Conclusion: The ethanolic extract of lemon verbena has higher antimicrobial effects on gram-positive bacteria. Therefore, it can be used in food and pharmaceutical industries as a natural antimicrobial agent. Considering the increasing resistance of bacteria to chemical antibiotics, more studies on lemon verbena and its antibacterial compounds are needed for treating infections.

Efeito antimicrobiano de extrato aquoso rico em polifenóis de casca de jabuticaba em Staphylococcus aureus e Escherichia coli

Abstract Jaboticaba peels are an important source of health-benefit and antimicrobial compounds. The present work aims to evaluate concentration of polyphenolics and the mode of action of aqueous extract from jaboticaba peels against Staphylococcus aureus and Escherichia coli. Jaboticaba peel extract showed minimum inhibitory concentration and minimum bactericidal concentration against S. aureus of 5.1 g L-1 and 10.1 g L-1, respectively; meanwhile, against E. coli the parameters were 2.0 g L-1 and 3.4 g L-1. Kinetics of viable cell counts indicated a bacteriolytic action against both bacteria and Scanning Electron Microscopy (SEM) showed that jaboticaba peel extract causes subtle morphological changes in bacterial cells. Concentration of total polyphenols in the extract was 1535.04±36.05 mg of gallic acid equivalent (GAE) mL-1, monomeric anthocyanins was 14.52 ± 0.98 mg of cyanidin 3-glucoside mL-1, condensed tannins was 0.49 ± 0.05 mg of epicatechin equivalent mL-1 and phenolic acids was 80.04 ± 4.11 mg of caffeic acid equivalent (CAE) mL-1, which have demonstrated well-documented antibacterial activity. In conclusion, jaboticaba peel aqueous extract may be an interesting natural preservative to control Gram-positive and Gram-negative bacteria growth when interacting with the bacteria cell wall.

Определение флавофосфолипола в лекарственных препаратах для ветеринарного применения методом диффузии в агар

Flavophospholipol is a phosphoglycolipid antibiotic that inhibits the development of gram-positive microorganisms in the gastrointestinal tract, slows down the growth of gram-negative bacteria Salmonella spp. and E.coli, without having a negative effect on lactobacilli and bifidobacteria, helps to reduce the extrachromosomal resistance of microorganisms to antibacterial agents, increasing their effectiveness. Preparations based on flavophospholipol are used for piglets and pigs, cattle and calves, rabbits and fur-bearing animals, poultry for prophylactic purposes in case of bacterial diseases, the pathogens of which are sensitive to flavofoslipol. In recent years, drugs based on flavophospholipol have been used in veterinary practice. In this regard, it is relevant to develop a methodology for the quantitative determination of flavophospholipol in medicinal preparations for veterinary use using the microbiological method (agar diffusion method). The authors established test strains capable of exhibiting growth inhibition under the action of flavophospholipol and its seed dose. By selecting various combinations, a nutrient substrate and its component composition were selected, depending on the needs of the microorganism, the incubation conditions and the concentration of the standard of the tested antibiotic were determined. The optimal experimental conditions for determining the quantitative determination of flavophospholipol in antimicrobial preparations by the agar diffusion method were established.