Growth Of Bacterial Cultures Research Articles

Microbial etiology and antibiotic resistance in urinary tract infections in children; view from an area where antibiotics are overused.

The aim of our study is to determine the uropathogenic causing urinary tract infections (UTIs) and their incidences, assess their antibiotic resistance, and determine an appropriate empirical antibiotic treatment strategy. We retrospectively analyzed the culture and antibiogram results of urine cultures of 49,706 patients aged 1 day to 18 years who applied to Diyarbakır Children's Hospital between March 2018 and October 2022. A total of 4,064 cases meeting the study criteria were recorded. Girls comprised 76.7% of the study population. While reproduction in urine culture was more common in boys in the 0-1 age group, there was a decrease in the number of boys with increasing age, and the most common culture growth was seen in girls in the 5-10 age group (p<0.001). Escherichia coli (E. coli) infections were more common in girls, while non-E. coli infections were more common in boys (p<0.001). Gram-negative bacterial growth in urine cultures was the most common growth type. In descending order, E. coli was grown in 68.1% of all cultures, Klebsiella spp in 12.6%, and Proteus spp in 3.9%. Less commonly, Pseudomonas spp (2.8%), Enterobacter spp (1.5%), and fungi (1.1%) were grown. Antibiotic resistance/sensitivity tests revealed resistance patterns most commonly against ampicillin (73.2%), amoxicillin-clavulanate (57.9%), cefuroxime axetil (46.7%), cefixime (51%), and ceftriaxone (40.5%), and less commonly against meropenem (1.7%), amikacin (2.4%), and nitrofurantoin (9.8%). Escherichia coli showed resistance most commonly against ampicillin (69.8%), amoxicillin-clavulanate (59.7%), and cefixime (51.3%), while non-E.coli bacteria showed resistance most commonly against ampicillin (84.6%), amoxicillin (52.0%), and cefixime (50%). Resistance against nitrofurantoin was lower in E. coli infections than non-E. coli infections, although the difference did not reach statistical significance (3.7% and 27%, respectively; p=0.149). In contrast, resistance against trimethoprim-sulfamethoxazole was more common in E. coli infections than non-E. coli infections, although the difference was not statistically significant (42% and 29.7%, respectively; p=0.093). Our study revealed that resistance has developed at very high rates against many oral and parenteral antibiotics that we use in the treatment of UTIs. If our rate of antibiotic use continues to increase this way, it is predicted that UTIs will, unfortunately, become untreatable with oral antibiotics. This upsetting point reached by our country, which is the state that uses antibiotics the most in Europe, exemplifies the importance of rational antibiotic use for the whole world.

A study of Antibiotic Susceptibility Pattern of Bacteria Isolates in Blood Culture in septicemic Children in Tertiary Care Hospital

Introduction: Sepsis in children is a life-threatening condition triggered by an infection. Most commonly, the infection is caused by bacteria. Antibiotic susceptibility patterns of bacterial isolates in blood cultures play a crucial role in the management of septicemia in children. Aim of the study: The aim of this study was to assess the antibiotic susceptibility pattern of bacteria isolates in blood culture in septicemic children. Methods: This cross-sectional study was conducted in Department of Paediatric, Dr. Sirajul Islam Medical College, Dhaka, Bangladesh, during the period from October 2021 to February 2023. Total 849 children aged less than 18 years with septicemia were included in this study. Result: The study involved 849 participants where majority were in the age group of 5 years or younger and with a near-even gender distribution. In this study, 10.1% tested positive for bacterial growth in blood cultures, with Pseudomonas (33.7%) and Staphylococcus epidermidis (22.1%) being most prevalent. Other organisms were also detected in varying proportions. The distribution of these organisms varied according to age and sex. Antibiotic sensitivity and resistance patterns were observed. A range of antibiotics showed different effectiveness, with varying levels of sensitivity and resistance against the bacterial isolates. Notably, Pseudomonas displayed considerable sensitive to cephalosporins (24.4%) and carbapenems (11.6%). Conclusion: The current study found that pseudomonas, staphylococcus epidermidis, and staphylococcus aureus were the most prevalent. Notably, a significant percentage of these bacteria displayed varying levels of antibiotic resistance, underscoring the challenge of managing sepsis in pediatric patients. These findings highlight the need for continuous surveillance of bacterial isolates and their resistance patterns.

Green synthesis of Cu-Mn co-incorporated ZnO nanoparticles for antibacterial and photocatalytic applications.

The synergistic effect of bimetallic co-incorporated metal oxides have gained enormous attention due to their unique optoelectronic properties. Herein, we present the green synthesis of ZnO, Cu-incorporated ZnO, Mn-incorporated ZnO, and Cu-Mnco-incorporated nanoparticles (ZnO NPs, CuZnO NPs, MnZnO NPs, MnCuZnO NPs) for antimicrobial and photocatalytic reduction applications using corn silk extract and industrial metal wastes. The as-synthesized NPs were characterized by using UV-visible absorption spectroscopy (UV-Vis), photoluminescence (PL) spectroscopy, Fourier-transformed infrared spectroscopy (FT-IR), powdered x-ray diffraction (XRD), and scanning electron microscopy (SEM). CuZnO, MnZnO, and MnCuZnO NPs efficiently inhibited bacterial culture growth. The photocatalytic reduction activity of as-synthesized NPs against the different concentrations of 4-nitrophenol (4-NP) in water was also investigated. CuZnO and MnCuZnO nanoparticles were to be efficient photocatalysts for reducing 4-NP into 4-aminophenol (4-AP). RESEARCH HIGHLIGHTS: Green synthesis of nanomaterials by agricultural and industrial wastes Cu and Mn co-incorporated ZnO NPs have shown good photocatalysis and antimicrobial activities Green approach for waste conversion to value-added products.

Evaluation of uropathogens isolated in the outpatient department of a tertiary care hospital in south India

: Urinary tract infections constitute a large percentage of cases encountered in outpatient departments at tertiary care hospitals. These infections have been associated with a rise in antimicrobial resistance, leading to high morbidity and mortality. This rise in drug resistance has been linked to an increase in unauthorized, unregularized use of higher generations of antibiotics, leading to the prevalence of multi drug resistant organisms in the community.: The aim of this study is to analyze the prevalence of various uropathogens in the general population, along with their antibiotic susceptibility patterns. : The study has been carried out for a period of six months, during which a total of 872 urine samples were collected from the outpatient department at Kamineni Academy of Medical Sciences and Research Center, Hyderabad. Urine samples were subjected to bacterial culture and significant bacterial growth was identified using the colony count method. Identification and antimicrobial susceptibility testing was done using an automated VITEK 2 compact system. A total of 236 cases (27.1%) showed significant growth of uropathogens. The common organisms isolated were These organisms were seen more commonly in females. Multidrug resistance has been noted in multiple uropathogens, especially to fluoroquinolones and cephalosporins. This study documented an increase in antimicrobial resistance of the uropathogens isolated at the outpatient department. Judicious use of antibiotics may aid in prevention of spread of antimicrobial drug resistance in the general population.

Complications to acute bacterial rhinosinusitis in children - a prospective study; bacterial cultures, virus detection, allergy sensitization and immunoglobulins.

Prospective studies of complications due to acute rhinosinusitis are lacking, bacterial cultures are hard to obtain and the role of airborne allergies, viruses and immunoglobulin levels are unclear. The aim was to investigate the role of bacteria, viruses, allergy and immunoglobulins in children hospitalized due to rhinosinusitis. A prospective cohort study in Stockholm, Sweden, of children up to 18 years of age, hospitalized due to acute bacterial rhinosinusitis, from April 1st, 2017 to April 1st, 2020. Of 55 children included, 51% had a positive viral nasopharyngeal PCR and 29% had a positive allergy sensitization test. A higher percentage of middle meatus cultures were positive for bacterial growth compared to nasopharyngeal and displayed a wider array of bacteria. Dominating bacteria were S. milleri in surgical (7/12 cases), S. pyogenes in middle meatus (13/52 cases), and S. pyogenes and H. influenza in nasopharyngeal cultures (8/50 cases respectively). Nasal cultures were negative in 50% of surgical cases. An association was found between S. pyogenes and peak CRP; H. influenzae and peak CRP; S. pneumoniae and peak CRP; and possibly between M. catarrhalis and days of IV antibiotics. Further, an association between influenza A/B and S. pyogenes; a positive viral PCR and lower grade of complication and peak CRP; and a possible association between influenza virus and lower grade of complication. Allergy sensitization was possibly associated with a higher number of days with IV antibiotics. No immunoglobulin deficiencies were found. There seem to be differences in the patterns of bacterial growth in nasopharyngeal, middle meatus and surgical cultures in children with complications to acute bacterial rhinosinusitis. Presence of certain viruses and sensitization to airborne allergies seem to play a role in complications to acute bacterial rhinosinusitis in children.

Treatment of mild to moderate clinical bovine mastitis caused by gram-positive bacteria: A noninferiority randomized trial of local penicillin treatment alone or combined with systemic treatment

Bovine mastitis is one of the most important diseases in modern dairy farming, as it leads to reduced welfare and milk production and increased need for antibiotic use. Clinical mastitis in Denmark is most often treated with a combination of local and systemic treatment with penicillin. The objective of this randomized clinical trial was to assess whether worse results could be expected with local intramammary treatment with penicillin compared with a combination of local and systemic treatment with penicillin in terms of the bacteriological cure of mild and moderate clinical mastitis cases caused by gram-positive bacteria. We carried out a noninferiority trial with a noninferiority margin set to a relative reduction in bacteriological cure of 15% between these 2 treatment groups to assess the effect of reducing the total antibiotic use by a factor of 16 for each treated case. Clinical mastitis cases from 12 Danish dairy farms were considered for enrollment. On-farm selection of gram-positive cases was carried out by the farm personnel within the first 24 h after a clinical mastitis case was detected. A single farm used bacterial culture results from the on-farm veterinarian, whereas the other 11 farms were provided with an on-farm test to distinguish gram-positive bacteria from gram-negative or samples without bacterial growth. Cases with suspected gram-positive bacteria were allocated to a treatment group: either local or combination. Bacteriological cure was assessed based on the bacterial species identified in the milk sample from the clinical mastitis case and 2 follow-up samples collected approximately 2 and 3 wk after ended treatment. Identification of bacteria was carried out using MALDI-TOF on bacterial culture growth. Noninferiority was assessed using unadjusted cure rates and adjusted cure rates from a multivariable mixed logistic regression model. Of the 1,972 clinical mastitis cases registered, 345 (18%) met all criteria for inclusion (full data). The data set was further reduced to 265 cases for the multivariable analysis to include only complete registrations. Streptococcus uberis was the most commonly isolated pathogen. Noninferiority was demonstrated for both unadjusted and adjusted cure rates. The unadjusted cure rates were 76.8% and 83.1% for the local and combined treatments, respectively (full data). The pathogen and somatic cell count before the clinical case had an effect on the efficacy of treatment; thus efficient treatment protocols should be herd- and case-specific. The effect of pathogen and somatic cell count on treatment efficacy was similar irrespective of the treatment protocol. We conclude that bacteriological cure of local penicillin treatment for mild and moderate clinical mastitis cases was noninferior to the combination of local and systemic treatment using a 15% noninferiority margin. This suggests that a potential 16-fold reduction in antimicrobial use per mastitis treatment can be achieved with no adverse effect on cure rate.

Increased growth temperature and vitamin B12 supplementation reduces the lag time for rapid pathogen identification in BHI agar and blood cultures.

Background: Rapid diagnostics of pathogens is essential to prescribe appropriate antibiotic therapy. The current methods for pathogen detection require the bacteria to grow in a culture medium, which is time-consuming. This increases the mortality rate and global burden of antimicrobial resistance. Culture-free detection methods are still under development and are not common in the clinical routine. Therefore, decreasing the culture time for accurately detecting infection and resistance is vital for diagnosis. Methods: This study investigated easy-to-implement factors (in a minimal laboratory set-up), including inoculum size, incubation temperature, and additional supplementation ( e.g., vitamin B12 and trace metals), that can significantly reduce the bacterial lag time (t lag). These factors were arranged in simple two-level factorial designs using Gram-positive cocci ( Staphylococcus aureus), Gram-positive bacilli ( Bacillus subtilis), and Gram-negative bacilli ( Escherichia coli and Pseudomonas aeruginosa) bacteria, including clinical isolates with known antimicrobial resistance profiles. Blood samples spiked with a clinical isolate of E. coli CCUG 17620 (Culture Collection University of Gothenburg) were also tested to see the effect of elevated incubation temperature on bacterial growth in blood cultures. Results: We observed that increased incubation temperature (42°C) along with vitamin B12 supplementation significantly reduced the t lag (10 - 115 minutes or 4% - 49%) in pure clinical isolates and blood samples spiked with E. coli CCUG17620. In the case of the blood sample, PCR results also detected bacterial DNA after only 3h of incubation and at three times the CFU/mL. Conclusion: Enrichment of bacterial culture media with growth supplements such as vitamin B12 and increased incubation temperature can be a cheap and rapid method for the early detection of pathogens. This proof-of-concept study is restricted to a few bacterial strains and growth conditions. In the future, the effect of other growth conditions and difficult-to-culture bacteria should be explored to shorten the lag phase.

Date Palm (Phoenix dactylifera L.) Flour as an Alternative Culture Media for the Growth of Escherichia coli and Bacillus cereus

The high cost of bacterial growth culture media can result in obstacles in the process of practicum or research in the field of microbiology. Date palm (Phoenix dactylifera L.) is the oldest fruit plant that grows in the Arabian Peninsula, North Africa and the Middle East. Dates are a source of high energy food with sugar content of 72% - 88%. This research was conducted to test the ability of date palm flour to grow Escherichia coli and Bacillus cereus bacteria as an alternative medium to replace NA media. In this study using total number of bacteria/ TPC (Total Plate Count) method to calculated the number of colonies of bacteria. The results of this study the number of colonies of Escherichia coli bacteria was more than the number of colonies of Bacillus cereus, that is 54 x 105CFU/g on concentration media 8 gr. When compared with NA media, date palm flour media can be used as an inexpensive alternative culture medium for bacteria.

Sterilization of New Endodontic Hand Files Stored in Dental Office Inventory: An In Vitro Study.

Background and objective Endodontic files, as supplied by the manufacturers to the endodontists, are not pre-sterile routinely. For both new and used equipment, rotary as well as manual,autoclaving is the standard sterilization protocol used in clinical and academic practice. In dentistry, instrument sterilization aims to safeguard patients from cross-contamination through instruments. Hence, every device should be thoroughly cleaned and sterilized. In this study, we aimed to evaluate the presence of various microorganisms in sealed and unsealedstored packsin dental offices and the probable impact of pre-sterilization procedures on the survival of these microorganisms. Materials and methods Two groups of root canal files varying in their packing method, boxes (Mani stainless steel K-files, ISO25, length 25 mm)and blister packs (UGD, ISO 25, length 25 mm), pre-sterile, opened/unopened were chosen and stored for about two weeks in the dental office and were classifiedinto three groups based on theirstorage and further classified into subgroups depending on their packing modes as follows: Group-1 (unopened and stored in shelf for two weeks), Subgroup-1A (boxes), Subgroup-1B (blister packs); Group-2 (unopened and stored on the countertop for two weeks), Subgroup-2A (boxes), Subgroup-2B (blister packs); Group-3 (opened and stored on the countertop for two weeks). After two weeks of storage, a set of three new files from each pack, both boxes and blisters, were placed in the nutrient broth to assess the turbidity and later cultured to assess the presence/absence and type of any bacterial growth. All the instruments in the three groups and subgroups were placed separately in the nutrient broth and carried to the microbiology lab for bacterial cultures. The entire procedure was carried out under the laminar flow. All these files in the nutrient broth were incubated for about 72 hours and the turbidity was assessed, and then the turbid bacteria were cultured on blood agar and MacConkeyagar plates for the presence/absence and the type of bacteria in each group and subgroups. Results All specimens, both opened/unopened boxes and blister packs, afterabout two weeks of storage, were cultured and observed for contamination. All the tested files groups showed bacterial culture growth both on blood agar and MacConkey agar plates. Group-1 (Subgroups 1A, 1B) boxes and blister packs unopened and stored on the shelf for two weeks demonstrated aerobic spore bacilli; Group-2 (Subgroups 2A, 2B) boxes and blister packs unopened and stored on the countertop for two weeks demonstratedGram-positive bacilli; Group-3 opened boxes and blisters stored on the countertop for two weeks demonstrated Micrococci and Gram-negative bacilli. Conclusion In the present study, all the packs, blisters and boxes, demonstrated the presence of bacterial growth irrespective of their storage in the dental office. Hence, in order to prevent any new infections from the operating field, sterilization of not only the old files but also the pre-sterilization of new files should be made mandatory.

Evaluation of acoustic pulse technology as a non-antibiotic therapy for bovine intramammary infections: Assessing bacterial cure vs. recovery from inflammation.

The spread of antimicrobial resistance (AMR) is a major threat to human and animal health. Therefore, new solutions are needed to prevent returning to a world without effective antibiotics. Mastitis in dairy cows is a major reason for antimicrobial use in food animal production, and mastitis-causing bacteria have the potential to develop AMR. In this study, acoustic pulse technology (APT) was explored as an alternative to antimicrobials for the treatment of mastitis in dairy cows. APT involves the local transmission of mechanical energy through soundwaves which stimulate anti-inflammatory and angiogenic responses in the udder. These responses promote udder recovery and enhance resistance to bacterial infections. We examined 129 Israeli dairy cows with mastitis in this prospective, controlled study to assess the efficiency of APT treatment on cure and recovery rates. An accurate diagnosis of suspected or confirmed infectious mastitis was made from cows having clinical signs of mastitis and/or somatic cell count (SCC) of above 400,000 cells/mL. The cows were divided into three groups: Group 1 (n = 29), cows with no bacterial findings (NBF); Group 2 (n = 82), cows with clinical signs of mastitis or SCC >400,000 cells/mL in the most recent test; and Group 3 (n = 18), cows with chronic mastitis (two or more tests with SCC >400,000 cells/mL within 3 months). All the cows received APT treatment, which involved 400 pulses on two sides of the infected quarter, delivered in three phases over 3 days. The cure for the mammary gland was indicated by the absence of bacterial growth in post-treatment cultures and recovery by a decrease in SCC to < 250,000 cells/mL in two of three post-treatment tests. In Group 2, cure and recovery rates were 67.1 and 64.6%, respectively, and were not significantly different between Gram-negative and Gram-positive infections. A similar recovery rate was found in NBF cows. However, in cows with chronic mastitis, both the cure and recovery rates were significantly lower (22.2 and 27.8%, respectively). These results have important implications for dairy farmers, as APT treatment could lead to substantial savings of up to $15,106/year in a 100-cow herd, considering the national estimated prevalence of mastitis and the cost of individual treatment. APT should be further investigated as a viable and sustainable alternative to antimicrobial therapy for mastitis, offering economic benefits to dairy producers and the possibility of preventing AMR.

Increased growth temperature and vitamin B12 supplementation reduces the lag time for rapid pathogen identification in BHI agar and blood cultures.

Background: The rapid diagnostics of pathogens is essential to prescribe appropriate and early antibiotic therapy. The current methods for pathogen detection require the bacteria to grow in a culture medium, which is time-consuming. This increases the mortality rate and the global burden of antimicrobial resistance. Culture-free detection methods are still under development and are not used in the clinical routine. Therefore decreasing the culture time for accurate detection of infection and resistance is vital for diagnosis. Methods: In this study, we wanted to investigate easy-to-implement factors (in a minimal laboratory set-up), including inoculum size, incubation temperature, and additional supplementation ( e.g., vitamin B12 and trace metals), that can significantly reduce the lag time (t lag). These factors were arranged in simple two-level factorial designs using Gram-positive ( Escherichia coli and Pseudomonas aeruginosa) and Gram-negative ( Staphylococcus aureus and Bacillus subtilis) bacteria, including clinical isolates with known antimicrobial resistance profiles. Blood samples spiked with a clinical isolate of E. coli CCUG17620 were also tested to see the effect of elevated incubation temperature on bacterial growth in blood cultures. Results: We observed that increased incubation temperature (42°C) along with vitamin B12 supplementation significantly reduced the t lag (10 - 115 minutes or 4% - 49%) in pure clinical isolates and blood samples spiked with E. coli CCUG17620. In the case of the blood sample, PCR results also detected bacterial DNA after only 3h of incubation and at three times the CFU/mL. Conclusions: Enrichment of bacterial culture media with growth supplements such as vitamin B12 and increased incubation temperature can be a cheap and rapid method for the early detection of pathogens. This is a proof-of-concept study restricted to a few bacterial strains and growth conditions. In the future, the effect of other growth conditions and difficult-to-culture bacteria should be explored to shorten the lag phase.

Real-Time Detection of the Bacterial Biofilm Formation Stages Using QCM-Based Sensors

Bacterial biofilms are a major cause of harm related to medical infections and biofouling. Thus, 80% of total infections are caused by biofilm-forming microorganisms. Consequently, knowledge of biofilm formation stages is crucial to develop effective treatments to prevent their formation in medical implants, tools, and devices. For this purpose, quartz crystal microbalance (QCM) sensors are becoming a good alternative to analytical methods for the real-time monitoring of bacterial growth in liquid media culture. In a previous paper, the authors described an affordable multi-channel measurement instrument based on QCM sensors. However, in order to validate its correct operation, complementary experimental measurements based on bacterial biofilm growth were performed. In this work, the experimental measurements that allow the identification of the different biofilm formation stages are described. The results obtained are discussed.

Suco de yacon como meio de cultivo e crioprotetor para cepas autóctones de Latilactobacillus sakei e Staphylococcus vitulinus

Abstract Yacon is mainly constituted of water and carbohydrates [single sugars and fructooligosaccharides (FOS)], thus being an excellent alternative for the growth and preservation of bacterial culture. Latilactobacillus sakei ACU-2 and Staphylococcus vitulinus ACU-10 comprised the autochthonous starter culture SAS-1 designed for the manufacture of dry sausages. This study evaluated the use of yacon juice as a potential growth medium and cryoprotectant for these bacteria. The growth medium was prepared with yacon juice supplemented with peptone and dipotassium phosphate. After growing, cells were resuspended in yacon juice (5, 10 and 25 mL/100 mL) and lyophilized. Viable cells were count before, immediately after lyophilization, and along 6 months of refrigerated storage. Both bacteria grew in every yacon concentration tested; however, juice concentration affected their growth. Latilactobacillus sakei grew at μ = 0.256 ± 0.01 giving the highest bacterial density at 10 mL/100 mL (Log DOmax 0.33 ± 0.01). While 5 mL/100 mL yacon juice provided the best conditions for S. vitulinus growth (μ = 0.215 ± 0.016; Log DOmax 0.32 ± 0.01). After lyophilization, the survival rate was 91.1% for L. sakei and 65.8% for S. vitulinus. Throughout storage, high cell counts suggested good stability of both bacteria. Results revealed that yacon juice comprises a nutritive substrate for the growth and cryopreservation of tested strains from the genus Latilactobacillus and Staphylococcus.

Freeform Illuminator for Computational Microscopy

Programmable illumination control is essential for many computational microscopy techniques. Conventional light source array is often arranged on a fixed grid of a planar surface for providing programmable sample illumination. Here, we report the development of a freeform illuminator that can be arranged at arbitrary 2-dimensional or 3-dimensional (3D) surface structures for computational microscopy. The freeform illuminator can be designed in a small form factor with a dense light source arrangement in 3D. It can be placed closer to the sample for providing angle-varied illumination with higher optical flux and smaller angular increment. With the freeform illuminators, we develop a calibration process using a low-cost Raspberry-Pi image sensor coated with a monolayer of blood cells. By tracking the positional shift of the blood-cell diffraction patterns at 2 distinct regions of the coded sensor, we can infer the 3D positions of the light source elements in a way similar to the stereo vision reconstruction approach. To demonstrate the applications for computational microscopy, we validate the freeform illuminators for Fourier ptychographic microscopy, 3D tomographic imaging, and on-chip microscopy. We also present a longitudinal study by tracking the growth of live bacterial cultures over a large field of view. The reported freeform illuminators and the related calibration process offer flexibilities and extended scope for imaging innovations in computational microscopy.

The non-protein fraction of embryonic stem cell secretome exerts antibacterial effects against antibiotic-resistant bacterial strains

In recent years, it has been extremely evident to seek out for new antibacterial agents, because the burgeoning problem of antibiotic resistance and the toxicity of many antimicrobial compounds has forced scientists to turn attention to alternative approaches. Investigating stem cell secretomes, including the non-protein portion, to find new antimicrobials is a promising area in the field. We examined an effect of the non-protein portion within the embryonic stem cell secretome on various bacterial strains, including antibiotic-resistant members. The non-protein fraction of the stem cell secretome was obtained by preparative high-performance liquid chromatography. Bactericidal activity was tested against eight museum bacterial strains and 206 clinical strains by comparing the secretome-related effects on growth of bacterial cultures. The museum strains showed some dose-dependent effects at concentrations of 25100 g/ml. Some bactericidal activity was shown at a concentration of 100 g/ml against the clinical strains of Gram-negative microorganisms of different species, but bacterial sensitivity to the secretome fraction varied, with growth stimulation being detected in some strains. Applying non-protein fraction of the stem cell secretome at higher concentrations of 1001000 g/ml showed no dose-dependent effect. The clinical strains of E. coli and P. aeruginosa were shown to have reduced bactericidal activity after 24-hour incubation. Thus, this study has shown that the non-protein fraction of the embryonic stem cell secretome exerts bactericidal effects against some bacterial strains. However, more detailed studies are needed to identify a mechanism of action and to determine the most effective dose as well as frequency of administration.

Design of organyl phosphate-based pro-drugs: comparative analysis of the antibiotic action of alkyl protecting groups with different degree of fluorination

Background. Molecular structures combining a phosphorus-containing counterpart and non-polar radicals are employed in design of pro-drugs as structural and functional groups necessary for transportation of drugs through cellular barriers. It is assumed that the carrier itself does not exhibit biological activity. However, the “organic phosphate – alkyl radical” complex may possess its own metabolic and pharmacological properties even in the absence of a drug moiety.The aim. To study the effect of fluorinated alkyl phosphates on the growth of bacterial test cultures in an agar medium and to identify conjugated metabolic markers using UV/visible spectroscopy.Materials and methods. The effect of six organyl phosphates on the growth of five types of bacteria under aerobic conditions was evaluated by the method of wells in an agar medium. For solutions containing cell metabolites of Pseudomonas aeruginosa, the absorption spectra were recorded at 250–280 nm. The principal component analysis (PCA) was used for multivariate comparative analysis of the spectra. Results. The studied organyl phosphates bearing the ethyl and propyl radicals are potential temporary carriers of the drug moiety, since they are capable of penetrating through cellular barriers. However, the fluorinated compounds exhibit bactericidal properties, the degree of which depends on the arrangement of fluorine atoms in the radical. The most active compounds are those exhaustively halogenated at the terminal carbon atom of the ethyl radical (-СН2-СF3), while non-fluorinated organyl phosphate is the least active. UV/visible spectra of P. aeruginosa cultivation products, according to PCA data, contain patterns reflecting the metabolic effects mediated by these structural features of the radicals.Conclusion. In terms of practical application of the studied compounds, the activity of a proantibiotic based on organyl phosphate with a non-fluorinated ethyl(propyl) radical will be determined only by the specificity of the drug moiety. Exactly the same molecule, but exhaustively fluorinated at the terminal carbon atom of the alkyl radical, is likely to be characterized by lower specificity and higher activity under the additive (or synergistic) action of metabolically active groups.

Preparation of activated carbon fibers (ACF) impregnated with metallic silver particles from cotton-woven wastes and its performance as an antibacterial agent

Although activated carbon has been the subject of numerous research applications in water treatment, purification, catalysis, etc., its production is mainly focused on granular and powder presentations due to the commonly used raw materials (e.g., wood, phenolic resin, etc.). Herein, we report an easily established methodology for preparing activated carbon fibers (ACF) using cotton-woven wastes as raw material under chemical activation with H3PO4. We tested different experimental conditions between the activating agent and the cotton fabrics using a randomized-block experimental design with the specific surface area of the activated fibers as the response variable. A highly microporous structure was obtained with an average specific surface area of 1060 m2/g and pore size of 17 Å. The fibers were later impregnated with metallic silver particles using an immersion process in AgNO3 solutions followed by drying and a thermal decomposition to promote the nucleation and precipitation of non-regular shaped silver particles with sizes on the micro and nanoscale within the fiber’s porous. The novel material showed a strong antibacterial effect and a complete inhibition of bacterial culture growth with silver contents as low as 200 ppm. • Cotton-woven wastes are suitable precursors for activated carbon fibers production. • Esterification of cellulose-based raw materials is the activation mechanism. • Production of activated carbon fibers with a specific surface area up to 1200 m 2 /g. • Considerably dimension and structural stability reduction from the original fiber. • High antibacterial activity due to the presence of metallic silver microparticles.

Disruption of MenT2 toxin impairs the growth of Mycobacterium tuberculosis in guinea pigs.

Toxin-antitoxin (TA) systems are abundantly present in the genomes of various bacterial pathogens. TA systems have been implicated in either plasmid maintenance or protection against phage infection, stress adaptation or disease pathogenesis. The genome of Mycobacterium tuberculosis encodes for more than 90 TA systems and 4 of these belong to the type IV subfamily (MenAT family). The toxins and antitoxins belonging to type IV TA systems share sequence homology with the AbiEii family of nucleotidyl transferases and the AbiEi family of putative transcriptional regulators, respectively. Here, we have performed experiments to understand the role of MenT2, a toxin from the type IV TA system, in mycobacterial physiology and disease pathogenesis. The ectopic expression of MenT2 using inducible vectors does not inhibit bacterial growth in liquid cultures. Bioinformatic and molecular modelling analysis suggested that the M. tuberculosis genome has an alternative start site upstream of the annotated menT2 gene. The overexpression of the reannotated MenT2 resulted in moderate growth inhibition of Mycobacterium smegmatis. We show that both menT2 and menA2 transcript levels are increased when M. tuberculosis is exposed to nitrosative stress, in vitro. When compared to the survival of the wild-type and the complemented strain, the ΔmenT2 mutant strain of M. tuberculosis was more resistant to being killed by nitrosative stress. However, the survival of both the ΔmenT2 mutant and the wild-type strain was similar in macrophages and when exposed to other stress conditions. Here, we show that MenT2 is required for the establishment of disease in guinea pigs. Gross pathology and histopathology analysis of lung tissues from guinea pigs infected with the ∆menT2 strain revealed significantly reduced tissue damage and inflammation. In summary, these results provide new insights into the role of MenT2 in mycobacterial pathogenesis.

SYNTHESIS AND BIOLOGICAL ACTIVITY OF 3d-­METAL COMPLEXES WITH BIS(PHOSPHONOMETHYL)AMINOSUNRIC ACID

New complexes of 3d-metals (Co2+, Ni2+, Zn2+) with bis(phosphonomethyl)aminosuccinic acid (H6BPMAS) have been synthesized. The complexes were studied in aqueous solutions at ratios M2+:H6BPMAS = 1:1 in a wide pH range (1÷10). Regardless of the nature of the metal, the formation of complexes of the general composition [M(HnBPMAS)(OH)m] (n= 4÷0, m=1÷0) is shown. The stability constants of the formed differently protonated complexes are calculated and diagrams of their distribution are plotted. It is shown that the process of complexation takes place most completely in the region of pH&gt;4. For all bis(phosphonomethyl)aminosuccinates of 3d metals, the dominance of the complex with one form of the ligand occurs in approximately the same pH ranges. A close order of change in the values of lgKst. complexes testifies to the same type of structure of their internal coordination sphere.&#x0D; Solid complexes of the composition Na4[MBPMAS]⋅4H2O were synthesized. Their composition, structure, and thermal characteristics were determined by the set of me­thods such as diffuse reflectance spectroscopy, IR spectroscopy, DTA and non-quantitative mass spectrometry. It is proved that the complexes have the structure of a distorted octahedron, in which the 3-d metal ions are bound to the oxygen atoms of the carboxyl and phosphonic groups and the tertiary nitrogen atom of the ligand. At the same time, two 5-membered (aminomethylenephosphonic and glycine) and one 6-membered (β-alanine) metallocycles are formed in bis(phosphonomethyl)aminosuccinates.&#x0D; The biological activity of H6BPMAS and its complexes with Ni(II) and Co(II) against non-pathogenic bacterial species of microorganisms Pseudomonas fluorescens and Pseudomonas aureofaciens was studied. The study of the activity of substances was carried out in a liquid sterile Hiss medium. The maxi­mum stimulating effect on the growth of bacterial cultures for the studied compounds was recorded at a concentration of 1 µM in 24 hours after the start of cultivation of mic­ro­organisms. The highest growth of microorganisms was recorded for metal complexes (50% Na4[CoBPMAS]·4H2O and 35% Na4[NiBPMAS]·4H2O). The maximum stimulating effect on the growth of bacterial cultures is shown by the Co(II) complex, which is able to initiate the synthesis of one of the most important growth hormones - heteroauxin.

Isolation and Characterization of Lytic Bacteriophages Active against Clinical Strains of E. coli and Development of a Phage Antimicrobial Cocktail.

Pathogenic E. coli cause urinary tract, soft tissue and central nervous system infections, sepsis, etc. Lytic bacteriophages can be used to combat such infections. We investigated six lytic E. coli bacteriophages isolated from wastewater. Transmission electron microscopy and whole genome sequencing showed that the isolated bacteriophages are tailed phages of the Caudoviricetes class. One-step growth curves revealed that their latent period of reproduction is 20-30 min, and the average value of the burst size is 117-155. During co-cultivation with various E. coli strains, the phages completely suppressed bacterial host culture growth within the first 4 h at MOIs 10-7 to 10-3. The host range lysed by each bacteriophage varied from six to two bacterial strains out of nine used in the study. The cocktail formed from the isolated bacteriophages possessed the ability to completely suppress the growth of all the E. coli strains used in the study within 6 h and maintain its lytic activity for 8 months of storage. All the isolated bacteriophages may be useful in fighting pathogenic E. coli strains and in the development of phage cocktails with a long storage period and high efficiency in the treatment of bacterial infections.