Mueller-Hinton Research Articles

In Vitro Antimicrobial Effectiveness of Calcium Hydroxide and Its Combination with Sodium Hypochlorite against Enterococcus Faecalis and Candida Albicans

The aim of this in vitro study was to evaluate and compare the antimicrobial effect of calcium hydroxide (〖Ca(OH)〗_2) and its combination with 5% sodium hypochlorite (NaOCL) as intracanal medicaments against Enterococcus faecalis (E. faecalis) and Candida albicans after one, three and seven days. Inoculate of these organisms (E. faecalis and candida albicans) were used to make lawn cultures on Mueller-Hinton with 5% defibrinated sheep blood agar and Mueller-Hinton agar. 60 wells with a depth of 4 mm were prepared for E. faecalis. Then 20 wells filled with 〖Ca(OH)〗_2, 20 wells filled with combination of 〖Ca(OH)〗_2 and 5% NaOCL, and last 20 wells were filled with distilled water as control. A similar procedure was conducted for Candida albicans. The zone of inhibition for each material used against a particular organism were measured and recorded after 1, 3, and 7 days. 〖Ca(OH)〗_2 in combination with 5% NaOCL is more effective than 〖Ca(OH)〗_2 alone against E. faecalis and Candida albicans at different time periods. E. faecalis was more resistant than Candida albicans to intracanal medicaments used. The antimicrobial effect depends on how long it remains inside the root canal. Mixing of 〖Ca(OH)〗_2 with 5% NaOCL had antimicrobial effect on both E. faecalis and Candida albicans and it was more effective against Candida albicans.

Mutant prevention concentrations, in vitro resistance evolution dynamics, and mechanisms of resistance to imipenem and imipenem/relebactam in carbapenem-susceptible Klebsiella pneumoniae isolates showing ceftazidime/avibactam resistance.

Klebsiella pneumoniae carbapenemase (KPC) variants selected during ceftazidime/avibactam treatment usually develop susceptibility to carbapenems and carbapenem/β-lactamase inhibitors, such as imipenem and imipenem/relebactam. We analyzed imipenem and imipenem/relebactam single-step mutant frequencies, resistance development trajectories and differentially selected resistance mechanisms using two representative K. pneumoniae isolates that had developed ceftazidime/avibactam resistance during therapy (ST512/KPC-31 and ST258/KPC-35). Mutant frequencies and mutant prevention concentrations were measured in Mueller-Hinton agar plates containing incremental concentrations of imipenem or imipenem/relebactam. Resistance dynamics were determined after incubation for 7 days in 10 mL MH tubes containing incremental concentrations of each antibiotic or combination, up to 64 times their baseline MIC. Two colonies per strain from each experiment were characterized by antimicrobial susceptibility testing and whole genome sequencing. The impact of KPC variants identified in resistant mutants on β-lactam resistance was investigated by cloning experiments. Imipenem/relebactam suppressed the emergence of resistant mutants at lower concentrations than imipenem, slowed down resistance development for both strains, and the resulting mutants yielded lower MICs of carbapenems and carbapenem/β-lactamase inhibitors than those selected with imipenem alone. Characterization of resistant mutants revealed that imipenem resistance was mainly caused by inactivation of OmpK36 and mutations in the KPC β-lactamase. Imipenem/relebactam-resistant mutants also maintained OmpK36 alterations, but mutations in KPC were much less frequent compared with those selected with imipenem alone. Genetic and biochemical characterization of the KPC derivatives identified in the resistant mutants confirmed their role in carbapenem resistance. Our data positions imipenem/relebactam as an attractive therapeutic option for combating ceftazidime/avibactam-resistant KPC-producing K. pneumoniae infections.

Extended-spectrum β-lactamase and carbapenemase producing Enterobacteriaceae among patients suspected with surgical site infection at Hospitals in Southern Ethiopia

BackgroundExtended-spectrum β-lactamase and carbapenemase-producing Enterobacteriaceae are an increasing problem for patients today. Data on clinical samples for ESBL and carbapenemase-producing Enterobacteriaceae for surgical site infection patients in developing countries are limited, including Ethiopia, mainly due to resource constraints. Hence, this study aimed to determine the prevalence of extended-spectrum beta-lactamase- and carbapenemase-producing Enterobacteriaceae among patients suspected to have surgical site infection at Hospital in Southern Ethiopia.Materials and methodsA hospital-based cross-sectional study was conducted on 422 suspected surgical site infections from June 1, 2022 to August 30, 2022 at Hospitals in Southern Ethiopia. Sociodemographic and clinical data were obtained by using a structured questionnaire. Clinical samples (pus, pus aspirates, and wound swabs) were collected aseptically and processed within 30 min by placing the swabs in sterile test tubes containing sterile normal saline (0.5 mL). Samples were cultured on blood and MacConkey agar plates. All positive cultures were characterized by colony morphology, Gram staining, and standard biochemical tests. Antimicrobial sensitivity tests were performed using Kirby Baur disk diffusion on Mueller–Hinton agar. ESBL production was confirmed using a double-disc synergy test (DDST) method. Carbapenemase production was assessed using the modified Hodge test. Logistic regression analysis was used to determine associated factors. A P-value < 0.05 were considered statistically significant.ResultBacteria belonging to the order Enterobacterales were cultured in 23.7% out of 422 patients with suspected surgical wound infection. Of all the isolates, Enterobacteriaceae (69 isolates) were the most frequent, with E. coli (29/69) followed by K. pneumoniae (14/69). Of 69 Enterobacteriaceae isolates, 66.6 % (46/69) were positive for ESBL production, and 21.7 (15/69) were positive for carbapenemase-producing Enterobacteriaceae. The majority of Enterobacteriaceae isolates showed sensitivity to meropenem (72.1%); however revealed 63.9% and 70.5% were resistant to gentamicin and ciprofloxacin, respectively. Similarly, a higher resistance rate to cefepime (91.8%), amoxicillin-clavulanic acid (98.4%), ceftriaxone (95.1%), and ceftazidime (91.8%). MDR rate of Enterobacteriaceae isolates was 25/61 (41%) among patients suspected for surgical site infection. The Multivariable analysis revealed that length of hospital stay in hospital [AOR = 3.81 (95% CI 2.08–6.95)] remained statistically significant factor associated with surgical site infection due to ESBL producing Enterobacteriaceae.ConclusionStudy results showed the severity of ESBL-producing Enterobacteriaceae is critical and CPE is alarming. Meropenem is the most effective antibiotic against the ESBL-producing Enterobacteriaceae. MDR rate of Enterobacteriaceae isolates was 61 (61%) among patients suspected for surgical site infection. Therefore, antibiotic selection should be based on the results of the culture and sensitivity tests.

Characterization and Prevalence of Antibiotic Resistance Staphylococcus aureus in Street Food: A Public Health Concern

Food samples containing Staphylococcus aureus pose a serious health risk. This study aimed to examine the prevalence of S. aureus strains in various food samples sourced from Mailsi and Multan. Many food samples including yogurt, bakery products, and raw and cooked food were examined for S. aureus. The isolated strains were confirmed through Mannitol agar fermentation, catalase, coagulase, and urease tests. Hemolysis on blood agar and biofilm formation were also assessed to determine toxin production. Antibiotic sensitivity testing was conducted using the Kirby Bauer method on MH agar, and multiple antibiotics were tested. Out of all samples, a total of 50 S. aureus strains were obtained, mainly from milk and milk-based products. Yellow colonies on mannitol salt agar confirmed S. aureus presence, with all isolates testing positive for coagulase, catalase, and urease. The presence of hemolysins: beta, gamma, and alpha were revealed by hemolysis assays. Biofilm assay results showed variation among the strains, with some categorized as strong, moderate, or weak biofilm formers. Regarding antibiotic sensitivity, most strains exhibited multidrug resistance, particularly against certain antibiotics. Vancomycin showed varying susceptibility patterns, some strains showed susceptibility and intermediate resistance, whereas only milk samples showed resistance. This study emphasizes the prevalence of MDR S. aureus strains in food samples. The study underscores the significance of antimicrobial stewardship programs and stringent food safety measures in preventing the spread of antibiotic-resistant strains and reducing foodborne illnesses. Further research is needed to explore the mechanisms behind antibiotic resistance and toxin production in S. aureus strains from food samples.

In vitro inhibition of Xanthomonas vasicola pv. musacearum, the causal agent of banana Xanthomonas Wilt, using medicinal plant extracts from North Kivu, Eastern Democratic Republic of Congo

Banana Wilt caused by Xanthomonas vasicola pv. musacearum (Xvm), has emerged as a significant threat to food security in eastern Democratic Republic of Congo (Kivu). Currently, the only means of combatting this biotic constraint is through best agricultural practices. The aim of this study was to evaluate the effectiveness of medicinal plants used in the Kivu provinces in inhibiting Xvm. Three in vitro experiments were conducted at laboratories of Uganda's National Agriculture Research Organization (NARO) and the International Institute of Tropical Agriculture (IITA) in South Kivu. The bacterial samples were collected from infected field-grown banana plants in South Kivu and isolated on Yeast Extract Peptone Agar (YPGA). Pure Xvm colonies were used for identification via i) Polymerase Chain Reaction (PCR) with specific primers and, ii) greenhouse inoculation trials. A completely randomized design was used for the three inhibition tests (1) on Mueller Hinton Agar (MHA) using disc diffusion with 10 plant extracts; (2) in liquid YPG Broth using 10 plant extracts; and (3) on MHA using disc diffusion with 19 plant extracts. The first two trials used plant extracts diluted in petroleum ether, while the third trial used 19 plant extracts diluted in methanol. After maceration, filtration, and solvent evaporation, 10 mg of extract was diluted in 80 µl of distilled water + 10 µl of Dimethylsulfoxide (DMSO). Ten µl of this solution was impregnated on perforated discs of Whatman filter paper. Zingiber officinale (ginger) and Ricinus communis (castor) were the most effective plant extracts in suppressing Xvm. Of the thirteen plant species identified as effective against the pathogen, the Myrtaceae and Euphorbiaceae families were the most represented. Based on these results, evaluating the effectiveness of the most promising plant extracts in disinfecting the metal blades of garden tools is recommended. In addition, various phytochemical groups present in plant extracts could be evaluated for their effectiveness in suppressing Xvm, especially phenols and tannins.

Collateral susceptibility-guided alternation of ceftolozane/tazobactam with imipenem prevents resistance development in XDR Pseudomonas aeruginosa biofilms

ObjectivesNew combinations of β-lactams and β-lactamase inhibitors, such as ceftolozane/tazobactam could be useful to combat biofilm-driven chronic infections by extensively resistant (XDR) Pseudomonas aeruginosa but resistance development by mutations in the Ω-loop of AmpC has been described. However, these mutations confer collateral susceptibility to carbapenems. Thus we aimed to evaluate the therapeutic efficacy and the prevention of resistance development of regimen alternating ceftolozane/tazobactam and imipenem. MethodsA carbapenem-resistant XDR P. aeruginosa clinical strain (ST175, 104-B7) and its isogenic imipenem-susceptible ceftolozane/tazobactam-resistant mutant derivative (AmpC T96I, 104-I9) were used. Experiments of single strains and mixed (104-B7 and 104-I9, 1:0.01 ratio) biofilms were performed. 48h biofilms (flow cell system) were treated for 6 days with either ceftolozane/tazobactam, 4/4 mg/L or the alternation of ceftolozane/tazobactam (2 days)-imipenem 4 mg/L (2 days) - ceftolozane/tazobactam (2 days). After treatment, biofilms were collected and plated on Mueller-Hinton agar± ceftolozane/tazobactam 4/4 mg/L. Structural dynamics were monitored using confocal laser scanning microscopy and images were processed with IMARIS software. At least, three independent triplicate experiments per condition were performed. Emerging resistant mutants were characterized through whole genome sequencing (Illumina). ResultsCeftolozane/tazobactam monotherapy failed to reduce the biofilms of the 104-B7 XDR strain and led to the selection of resistant mutants that showed AmpC Ω-loop mutations (T96I, L244R or aa236Δ7). On the contrary, alternation with imipenem enhanced activity (3 Logs reduction at day 6) and prevented the emergence of ceftolozane/tazobactam-resistant mutants. Likewise, treatment with ceftolozane/tazobactam dramatically amplified the resistant strain 104-I9 in mixed biofilms (>90 % of the population), while the alternation regimen counterselected it. ConclusionsCollateral susceptibility-guided alternation of ceftolozane/tazobactam with imipenem effectively prevented the selection of resistant mutants and thus could be a potential therapeutic strategy for the treatment of P. aeruginosa XDR chronic infections.

Synergy of photoluminescence emission and antibacterial activity of Ag-Cu2O nanocomposite

Conglomerate nanocomposites comprising metal and metal oxide hold significant potential for exhibiting properties that surpass the combined characteristics of their individual components, owing to the interactions occurring at the interfaces between the metal and metal oxide elements. In this study, we present the synthesis of Cu2O nanoparticles (NPs) (with diameters ranging from 40 to 53 nm) and Ag-Cu2O nanocomposites using an aqueous solution method at room temperature, employing varying concentrations of Ag NPs. Through optical absorption studies, we determined the optical band gap of Cu2O NPs in 0.5Ag-Cu2O, 1Ag-Cu2O, and 1.5Ag-Cu2O nanocomposites samples to be 2.13 eV, 2.25 eV, 2.34 eV, and 2.41 eV, respectively. The x-ray diffraction data are analysed using the Williamson–Hall technique and revealed noteworthy variations in microstructural characteristics such as strain and stress within the Cu2O nanocrystallites fabricated under different Ag concentrations. The nanocomposites amplified the intensities of violet-blue, blue, and green photoluminescence (PL) emissions, attributable to the interfaces between Ag and Cu2O, lattice mismatches, and the induced microstructural parameters lattice strain, and stress of Cu2O nanocrystallites. The enhanced PL intensities can be attributed to the influence of the local electric field on the Ag core composites. The Ag-Cu2O nanostructure exhibits potential applications in water purification technologies, while the PL emission properties and low band gap (∼2.13 eV) hold promising applications in optoelectronic devices. The antibacterial activities of Cu2O and Ag-Cu2O nanomaterials against Enterococcus faecalis and Escherichia fergusonii are examined using MH agar well plate diffusion methods. Here, Ag NPs enhance bactericidal effectiveness through enhanced interaction with bacteria and the release of Ag+ ions, while the Cu2O shell discontinuity on Ag NPs contributes to their unique antibacterial properties.

Isolation and molecular characterization of multi-drug resistant uropathogenic Escherichia coli from urine samples: Insights into urinary tract infection management

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) present a significant global health burden. With UPEC responsible for approximately 90 % of UTIs, understanding its mechanisms of virulence and antibiotic resistance is paramount for effective treatment strategies. This study aimed to investigate the prevalence of multi-drug resistant (MDR) E. coli strains in urinary tract infections and to elucidate the molecular mechanisms underlying their resistance. A total of 150 E. coli isolates were obtained from urinary tract infection specimens collected patients at Doctor’s Diagnostic Centre in Kalyan Nagar, Bangalore over four months November 2022 to February 2023. Isolation and screening of pathogenic E. coli were conducted using Eosin Methylene Blue Agar and Nutrient Agar, followed by identification through gram staining and biochemical characterization tests. Antibiotic susceptibility testing was performed using Mueller-Hinton agar and various antibiotic discs. Phenotypic and molecular identification of extended-spectrum beta-lactamase (ESBL) producers were conducted, along with the screening for specific antibiotic resistance genes using polymerase chain reaction (PCR). Of the 150 E. coli isolates, 57.3 % were found to be multi-drug resistant, with all 35 isolates from hospitalized patients exhibiting MDR characteristics. Phenotypic and molecular analyses revealed the presence of ESBL-producing isolates, with the blaCTX-M, blaTEM, and blaSHV genes detected in PCR assays. Plasmid extraction and PCR assays further identified the presence of plasmid-encoded carbapenemase genes (blaOXA-48, blaNDM-1, blaKPC-2), as well as other antibiotic resistance genes including those conferring resistance to fluoroquinolones. The results underscore the alarming prevalence of MDR E. coli strains in urinary tract infections, particularly in hospitalized patients. Molecular characterization revealed the diverse genetic mechanisms contributing to antibiotic resistance, including the presence of ESBLs and plasmid-encoded resistance genes. These findings emphasize the urgent need for surveillance and infection control measures to mitigate the spread of MDR pathogens and the development of alternative therapeutic strategies to combat antibiotic resistance in UTIs.

A study on pathogenic aerobic bacteria of surgical site infection and their antimicrobial susceptibility pattern in patients attending a hospital in Bhubaneswar, Odisha

Abstract: Introduction: Identification of bacterial pathogens and their antibiotic susceptibility testing are vital for the effective treatment of surgical site infection (SSI). Objective: The objective of the study was to study the bacterial pathogens in patients with SSI and their antibiotic susceptibility pattern. Methods: Pus samples were collected using sterilized swab stick, and then, the samples were cultured in MacConkey and Blood agar and incubated for 24 h in bacterial incubator. The identification was done by using colony morphology, Gram staining technique, and biochemical tests. After identification, the antibiogram of organisms was done using Mueller–Hinton agar. Results: A total of 76 pus samples were collected from different specialties from SSIs. Out of which 53 samples were culture positive. The number of male patients who had SSI was higher than females. Maximum SSIs were observed in the orthopedics department followed by the surgery department and gynecology department. SSIs in surgery and orthopedics department were commonly seen in the age group 41–60 years. In the obstetrics and gynecology department, SSIs were seen mostly in the age group 21–40 years. In the surgery and orthopedics department, Staphylococcus aureus was the predominant organism and Klebsiella spp was the most common Gram-negative isolate. In the gynecology department, S. aureus was the predominant organism followed by Acinetobacter spp. Maximum sensitivity to Vancomycin and Linezolid was seen as the only Gram-positive isolate in all specialties. Gram-negative isolates from the Enterobacteriaceae family of all specialties were sensitive to tigecycline followed by imipenem and meropenem. Nonfermenters were mostly sensitive to polymyxin b/colistin, imipenem, and meropenem. Conclusion: The study gives an insight into aerobic bacterial pathogens and their antibiotic-sensitivity patterns isolated from SSI and there should be surveillance of SSI which helps to reduce the rate of SSI as well as appropriate use of antibiotics.

Exploring Myrrh Oil as a Natural Antimicrobial Agent Against Oral Pathogens: An In Vitro Research

Background: While contemporary pharmaceuticals play a critical role in managing oral infections, there remain persistent concerns regarding their chemical composition and potential adverse effects. This apprehension has led to an increased focus on exploring natural alternatives, particularly herbal substances, for their potential therapeutic benefits in oral health. Aim: This study aimed to examine the antibacterial properties of myrrh oil against common oral bacteria, including Candida, Escherichia coli, Klebsiella, and Staphylococcus aureus, and to assess its suitability as a natural alternative in oral healthcare. Methods: Oral swabs were obtained from 50 individuals from various socioeconomic backgrounds. The isolated organisms were cultivated on different types of media and identified using established microbiological methods. Bacterial growth inhibition was evaluated by culturing subsequent cultures on Muller-Hinton agar with myrrh oil. This agar medium was selected for its suitability in evaluating myrrh oil’s suppressive impact on oral bacteria proliferation. Results: Candida demonstrated abundant proliferation on the control media but showed a reduction in colony-forming units when treated with myrrh oil. E. coli, Klebsiella, and Staphylococcus aureus exhibited decreased growth and suppressed colony formation when exposed to myrrh oil. Conclusion: These findings indicate that myrrh oil can prevent the growth of oral bacteria, making it a promising natural antibacterial agent for managing oral health. Additional investigations are needed to examine the safety, ideal dosage, and clinical feasibility of this treatment.

Evaluation of the Antibacterial Effects of the Punica granatum Peels Extracts Against some Pathogenic Bacteria: An In vivo and In vitro Study

Background: This study aimed to evaluate the antibacterial effects of Punica granatum extract on such pathogenic bacteria as Staphylococcus aureus and Escherichia coli. Materials and methods: The samples from 130 patients with skin infections in Baghdad, Iraq, aged between 15 and 60 over years were collected for this study. The study collected. Each isolate was positively identified using morphological, cultural, and biochemical assays as detailed in the reference. The P. granatum peels were air-dried and powdered. Then 25g were extracted using 500 mL of water and ethanol on Soxhlet equipment for 72 hours. The extracts were then cooled, filtered, and concentrated at 40oC to get the crude extract; it was kept at four degrees centigrade in dark vials until use. The extracts were tested for the presence of alkaloids, tannins, flavonoids, glycosides, as well as steroidal terpenes. The efficacy of antimicrobial effects was calculated using well-diffusion techniques on Muller Hinton Agar (MHA). The plates were injected with a standardized suspension of the test isolates against McFarland tube 0.5. Five wells, each measuring five millimeters in diameter, were evenly spaced out using a sterile standard core borer. The well bottoms were sealed with sterile molten nutritional agar to prevent the extract from leaking out from beneath the agar. The aqueous and ethanolic crude extracts dissolved in DMSO served as positive controls, while sterile water and 10% DMSO served as negative controls. Each extract was diluted to a final concentration of 50, 100, or 200mg/ml, and 25 ml was added to the appropriate well on the infected plate. The plates were then incubated for 24 hours at 37 degrees Celsius. A millimeter-calibrated ruler was used to measure the size of the resultant inhibitory zones. The zone of inhibition of the test microorganisms at that dose was calculated as the mean of three measurements. Results: Clinical isolates of E. coli and S. aureus were inhibited by pomegranate extracts at a concentration of 200mg/ml compared to other concentrations, and this extract concentration showed a non-significant difference with chloramphenicol (P<0.01). The study revealed that pomegranate peel extract significantly reduced E. coli levels in feces and increased survival rates in rats. On the first day, E. coli concentrations were much higher in the control group (G2) compared to the treatment group (G3). By day 6, all rats in the control group had died, while all rats in the treatment group survived. Pomegranate peel extract shows notable antibacterial properties, impacting bacterial membrane permeability and cell survival. The variation in extract composition affects its efficacy. Conclusion, Pomegranate peel extract significantly reduced E. coli levels and improved survival rates in rats. On day 6, all rats in the control group died, while all in the treatment group survived. The extract's antibacterial effects and impact on bacterial membranes highlight its potential as a therapeutic agent.

Effect of The Temperature on The Size of Inhibition Zone of the Clindamycin, Levofloxacin, Tetracycline, and Trimethoprim Activity Against Staphylococcus aureus ATCC 25923

Antibiotic sensitivity should be tested. In the sensitivity test, there are technical factors that influence the formation of the inhibition zone diameter. Based on several research one of the technical factors that affect the diameter of the inhibition in the disc diffusion method is the temperature incubation of the media, this must be examined so that it can be controlled to ensure the validity of the sensitivity test results. This study aims to determine the mean, difference, and analyze the diameter of the inhibition zone of the antibiotics namely Clindamycin, Levofloxacin, Tetracycline, and Trimethoprim against Staphylococcus aureus on Mueller-Hinton agar media with incubation temperatures of 33°C, 34°C, 35°C, 36°C and 37°C for 18 hours. This research is observational, with a cross-sectional design. The data used are primary data with 100 data on the diameter of the antibiotic inhibition zone, obtained by measuring the diameter of the inhibition zone with different incubation temperatures. The selection of antibiotics is based on the mechanism of action of antibiotics inhibiting bacteria namely, the cell wall or membranes that surrounds the bacterial cell; the machineries that make the nucleic acids DNA and RNA and the machinery that produce proteins (the ribosome and associated proteins) with a range of inhibition zones based on Internal Quality Control CLSI. The data will be processed univariately and the Repeated Measure statistical test to determine the significance of the difference in the diameter of the formed inhibition zone using the ANOVA test. The results of the measurement of the inhibition zone diameter on the incubation temperature variation showed a significant difference with p-value 0.000 for Levofloxacin, Tetracycline and Trimethoprim, while for p-value Clindamycin is 0.010. Levofloxacin, Tetracycline, and Trimethoprim antibiotics, the higher the incubation temperature, the average diameter of the inhibition zone is smaller, while for Clindamycin the higher the incubation temperature, the higher the average diameter of the inhibition zone is the same. There is an effect of incubation temperature volume on the diameter of the antibiotic inhibition zone in the disc diffusion method antibiotic sensitivity test. The research indicates that incubation temperature affects the diameter of the antibiotic inhibition zone in disc diffusion tests, underscoring the need for standardized and precise testing conditions to ensure accurate and reliable antibiotic sensitivity results.

ANTIBIOGRAM ASSAY OF E.COLI ISOLATES IN PATIENTS WITH URINARY TRACT INFECTION

Screening of prevalent bacterial pathogens for antibiotic susceptibility profiles in different regions is necessary. E. coli and other pathogens are so common in our environment that it is essential to monitor trends in antibiotic susceptibility regularly. Objective: The aim of the study was to find out the antibiotic susceptibility pattern of E.coli isolates in patients with urinary tract infection. Methods: This study was conducted at the Saidu Group of Teaching Hospital Swat after taking permission from the ethical committee of the institute. We collected a total of 900 urine samples from males and females of all ages for culture and sensitivity. The Kirby-Bauer disc diffusion method was used to assess the antibiogram on Mueller-Hinton agar. The plates were kept in incubator at 37°C for the 48 hours, and the inhibition zone was measured. The antibiogram was performed by Kirby-Bauer disc diffusion method applying various antibiotics. The bacterial strains were classified in to three majors groups on the basis of antibiotic susceptibility pattern resistant (R) sensitive (S), and intermediate (I). Data was statistically analyzed presented in the tables and figures. Results: For culture and sensitivity testing, a total of 900 urine samples from patients with suspected UTIs were obtained from the several departments' inpatient and outpatient to the microbiological lab. Substantial bacteriuria was noted in 250 (27.7%). The most prevalent bacteria isolated was E.coli (55%) and its antibiogram was carried out. Ampicillin had the highest proportion of resistance (96.1%), followed by Ceftriaxone (91%), Moxifloxacin (87.1%), and Ceftazidime (75.5%). Whereas it was sensitive to Fosfomycin (94.2%), followed by Sulzone ( 84.3%), Imepinem (84.3%) and Amikacin (78%). Conclusion: It was concluded from the current study that the most prevalent bacteria causing urinary tract infection was E.coli, and this bacteria showed remarkable resistance against Ampicillin Ceftriaxone, Moxifloxacin, and Ceftazidime. The most used bacterium antibiotics for therapy were Fosfomycin, Imepinem and Amikacin. Therefore, antibiotic susceptibility should be considered before therapy.

"Characterization Of Acinetobacter Baumannii Resistance And Prevalence In Icu Settings: Insights From A Retrospective Study."

Purpose: This study aimed to determine the prevalence and antibiotic resistance patterns of Acinetobacter baumannii isolated from ICU patients at a tertiary care hospital. Understanding these patterns is crucial for informing infection control strategies and treatment protocols. Material and methods: A retrospective cross-sectional study was conducted at the Department of Microbiology, Government Medical College & New Civil Hospital, Surat. Clinical samples from ICUs were analyzed from January 2023 to December 2023. A total of 4,432 samples were processed for culture and sensitivity testing. Identification of A. baumannii was performed using Gram staining, motility tests, and biochemical tests. Antimicrobial susceptibility was assessed using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar, with results interpreted according to CLSI guidelines. Results: Out of 4,432 samples, 650 showed significant bacterial growth. Acinetobacter baumannii was identified in 144 samples, accounting for 22% of all ICU culture-positive cases. The highest number of isolates was from the Medical ICU (MICU), representing 44% of total isolates. Over 95% of A. baumannii isolates were multidrugresistant (MDR). Resistance rates were highest for Ceftriaxone and Imipenem (92%), followed by Cefepime (90.2%). Colistin susceptibility was observed in all pan-drug-resistant isolates. Discussion: The high prevalence of A. baumannii in ICU-acquired infections and the observed multidrug resistance highlight a significant challenge in managing these infections. The resistance patterns are consistent with recent studies, confirming the persistent difficulty in treating A. baumannii infections with conventional antibiotics. The effectiveness of Colistin for pan-drug-resistant isolates underscores its continued relevance, despite concerns about potential side effects. Conclusion: The study reveals a high prevalence of multidrug-resistant A. baumannii in ICU settings, emphasizing the urgent need for effective infection control measures and antimicrobial stewardship. Continuous monitoring and stringent infection prevention practices are essential to combat the growing threat of A. baumannii in ICU environments

Effect of medicated toothpastes and Tooth Mousse on cariogenic microbes of the oral cavity: An in vitro study.

Dental caries, commonly known as tooth decay is a widespread oral health problem mainly attributed to the activity of cariogenic bacteria, such as Streptococcus mutans and Lactobacillus species. Tooth Mousse, containing remineralizing agents, herbal and fluoride containing toothpaste with antimicrobial agents have been developed to target cariogenic bacteria. Herbal, fluoride toothpaste, and Tooth Mousse are commonly prescribed to prevent, reduce, and control dental caries. This study aims to analyze the effect of Tooth Mousse and medicated toothpastes on S. mutans and Lactobacillus acidophilus using direct contact test. L. acidophilus and S. mutans were cultured on Mueller-Hinton agar (MHA-Hi media) using sterile cotton swabs and plates were dried for 15 min. Toothpastes (Dabur Red, Pepsodent) and Tooth Mousse were used at 1:1 dilution using sterile pyrogen-free distilled water. Fifty microliter of toothpastes and Tooth Mousse were introduced into each well. The plates were incubated at 37°C for 24 h. The antimicrobial activity was evaluated by measuring the diameter of zones of inhibition (mm). The toothpaste containing fluoride (A) showed greater zone of inhibition compared to herbal toothpaste (B) whereas Tooth Mousse (C) did not show any zone of inhibition. Among herbal and fluoride toothpaste, fluoride containing toothpaste showed more zone of inhibition thereby attributing to its increased antimicrobial property on S. mutans and L. acidophilus.

Reversion of KPC-114 to KPC-2 in ceftazidime-avibactam- resistant/meropenem-susceptible Klebsiella pneumoniae ST11 is related to low mutation rates.

Klebsiella pneumoniae strains that produce Klebsiella pneumoniae Carbapenemase (KPC) variants displaying resistance to ceftazidime-avibactam (CZA) often remain susceptible to meropenem (MEM), suggesting a potential therapeutic use of this carbapenem antibiotic. However, in vitro studies indicate that these sorts of strains can mutate becoming MEM-resistant, raising concerns about the effectiveness of carbapenems as treatment option. We have studied mutation rates occurring from the reversion of MEM-susceptible KPC-114 to MEM-resistant KPC-2, in CZA-resistant K. pneumoniae belonging to ST11. Two-step fluctuation assays (FAs) were conducted. In brief, initial cultures of KPC-114-producing K. pneumoniae showing 1 µg/mL MEM MIC were spread on Mueller-Hinton agar plates containing 2-8 µg/mL MEM. A second step of FA, at 4-16 µg/mL MEM was performed from a mutant colony obtained at 2 µg/mL MEM. Mutation rates were calculated using maximum likelihood estimation. Parental and mutant strains were sequenced by Illumina NextSeq, and mutations were predicted by variant-calling analysis. At 8 µg/mL MEM, mutants derived from parental CZA-resistant (MIC ≥ 64 µg/mL)/MEM-susceptible (MIC = 1 µg/mL) KPC-114-positive K. pneumoniae exhibited an accumulative mutation rate of 3.05 × 10-19 mutations/cell/generation, whereas at 16 µg/mL MEM an accumulative mutation rate of 1.33 × 10-19 mutations/cell/generation resulted in the reversion of KPC-114 (S181_P182 deletion) to KPC-2. These findings highlight that the reversion of MEM-susceptible KPC-114 to MEM-resistant KPC-2, in CZA-resistant K. pneumoniae ST11 is related to low mutation rates suggesting a low risk of therapeutic failure. In vivo investigations are necessary to confirm the clinical potential of MEM against CZA-resistant KPC variants.IMPORTANCEThe emergence of ceftazidime-avibactam (CZA) resistance among carbapenem-resistant Klebsiella pneumoniae is a major concern due to the limited therapeutic options. Strikingly, KPC mutations mediating CZA resistance are generally associated with meropenem susceptibility, suggesting a potential therapeutic use of this carbapenem antibiotic. However, the reversion of meropenem-susceptible to meropenem-resistant could be expected. Therefore, knowing the mutation rate related to this genetic event is essential to estimate the potential use of meropenem against CZA-resistant KPC-producing K. pneumoniae. In this study, we demonstrate, in vitro, that under high concentrations of meropenem, reversion of KPC-114 to KPC-2 in CZA-resistant/meropenem-susceptible K. pneumoniae belonging to the global high-risk ST11 is related to low mutation rates.

Antarctic Streptomyces: Promising biocontrol agents for combating Fusarium oxysporum f. sp. cubense

Fusarium wilt of Banana (FWB) caused by Fusarium oxysporum f. sp. cubense (Foc) poses a significant threat to the banana industry, with current inadequate control measures. This study evaluated the antifungal potential of nine Streptomyces strains isolated from Antarctic soil samples, using Casein-Starch media to stimulate the production of antifungal compounds. The inhibition spectrum against Foc was assessed under laboratory conditions using the well diffusion on Mueller-Hinton agar, with antifungal activity measured in arbitrary units (AU/mL) and minimum inhibitory concentration (MIC) tested using ethyl acetate extracts. Among the nine isolates, K6 and E7 were closely related to Streptomyces polyrhachis and Streptomyces fildesensis, exhibited significant antifungal activity, with K6 and E7 showing 320 and 80 AU/mL, and MIC values of 250 and >500 ppm, respectively. These findings highlight K6 and E7 as potential biocontrol agents against Foc, offering new avenues for sustainable Fusarium wilt management in banana cultivation.

Surveillance of In Vitro Activity of Cefiderocol Against Carbapenem-Resistant Gram-Negative Clinical Isolates in a Tertiary Care Hospital.

Antibiotic resistance among Gram-negative bacterial isolates is increasingly observed. With the emergence of carbapenem-resistant and pan-resistant pathogens, treating these resistant infections is becoming more challenging due to the limited number of effective drugs. There is a desperate need for the discovery of new antibiotics with novel mechanisms of action. Cefiderocol is one such novel antibiotic with a unique siderophore-based mechanism of action, which has been recently approved for clinical use against drug-resistant pathogens. The present study aims to identify the in vitro activity of cefiderocol against major carbapenem-resistant clinical isolates, including those resistant to colistin. One hundred and one carbapenem-resistant clinical isolates were included in the study. Identification and antibiotic susceptibility testing were performed using the automated VITEK® 2 Compact (bioMérieux SA, Marcy-l'Étoile, France) identification and susceptibility testing system, except for colistin and cefiderocol. Colistin resistance in Enterobacterales and Pseudomonas aeruginosa was assessed using the agar dilution minimum inhibitory concentration method, while for Acinetobacter baumannii, broth microdilution method was employed. Cefiderocol susceptibility testing was conducted using the Kirby-Bauer disc diffusion method with 30 µg discs on standard Mueller-Hinton agar plates. For selected isolates, cefiderocol minimum inhibitory concentration detection was performed using broth microdilution with iron-depleted cation-adjusted Mueller-Hinton broth. Of the total 101 isolates, the majority (75, 74.25%) were Enterobacterales which includedKlebsiella pneumonia (42, 41.58%) and Escherichia coli (33, 32.67%), followed by Pseudomonas aeruginosa (13, 12.87%) and Acinetobacter baumannii (10, 9.9%). Only three (2.97%)of the isolates were Stenotrophomonas maltophilia. Most of the isolates were susceptible to cefiderocol, with only four (3.96%) isolates showing resistance. Colistin resistance was observed in six (6.12%) of the isolates. There was a good correlation between disc diffusion testing and broth microdilution testing for the detection of cefiderocol-resistant isolates. No cross-resistance with colistin was observed, as all colistin-resistant isolates were uniformly susceptible to cefiderocol Conclusion: Cefiderocol is highly effective with good in vitro activity against the majority of carbapenem-resistant pathogens. While some isolates do show resistance, it is relatively uncommon. Given its safety profile compared to colistin, cefiderocol can serve as an alternative to colistin to treat carbapenem-resistant infections and it may be considered even for the management of colistin-resistant cases. Disc diffusion testing is a reliable method for identifying cefiderocol-resistant isolates in routine clinical and diagnostic laboratories, especially in resource-limited settings.

Bacterial growth assessment of extraction pliers following tooth extraction in culturing bacterial on various media: a quasi-experimental study

ABSTRACTIntroduction: Tooth extraction injury potentially creating an entry point for bacteria that may cause infection. Dental extraction tools that come into contact with a patient's oral cavity contain many bacteria which can be opportunistic and pathogenic. The purpose of this study was to examine the bacterial growth on tooth extraction pliers following tooth extraction in culturing bacteria on various media. Methods: Type of study is a quasi-experimental research design, using pre and post-test analysis. It was conducted in September–October 2021 at the Teeth and Mouth Dentistry Hospital (RSGM), Universitas Syiah Kuala, focusing on the swab sampling of tooth extraction pliers. The sample examination stage was conducted at the Faculty of Dentistry Laboratory. The study involved culturing bacterial on various media, including NA (Nutrient Agar), MHA (Mueller Hinton Agar), TSA (Triptic Soy Agar), TYS20B (Trypticase Soy-Yeast 20% Sukrose with Bacitracin), and performing gram staining under a microscope. Results: NA media: out of 16 samples cultured, 8 were not covered by bacteria, while the other 8 were. MHA media: all samples were overgrown with bacteria, but each 8 had different characteristics. 9 samples of TYS20B medium were overgrown with bacteria, while the other seven did not show signs of bacterial overgrowth. On TSA media, 5 samples were not overgrown with bacteria, 9 samples were overgrown with bacteria exhibiting solid, yellowish white, and not slimy, and the other 2 samples contained bacteria that were soft, yellowish white, and slimy. Conclusion: Bacillus sp., Diphtheroid basil sp., and Streptococcus mutans were found grown on the agar media. In general, MHA media is the most effective general growth medium, while TYS20B media is the best media for Streptococcus mutans growth.

Study of Aerobic Bacteria from Surgical Site Infection and their Antibiotic Susceptibility Pattern at a Tertiary Care Centre in Eastern Nepal

Background: The surgical site infections are the third most common nosocomial infection. The most common organism is Staphylococcus aureus. Nepal has a 4-7% overall prevalence rate for surgical site infection. The study objective was to find out the aerobic bacteria from surgical site infection and their antibiotic susceptibility pattern in a tertiary care hospital in Nepal. Materials and Methods: A descriptive cross-sectional study was conducted at a tertiary care center with effect from September 2022 to September 2023 approval from the Institutional Review Committee. Pus samples were taken from the postoperative wound infection site and submitted to the microbiological laboratory for culture and sensitivity. Gram-positive aerobic bacteria and gram-negative aerobic bacteria were isolated and identified by standard microbiological procedures. An antimicrobial susceptibility test was done on Muller-Hinton agar using the Kirby Bauer disc diffusion method. The result was interpreted according to clinical and laboratory standard institute guidelines. Results: The rate of surgical site infection was 22.24% and the most common organisms isolated were Staphylococcus aureus followed by Escherichia coli and Pseudomonas aeruginosa. All the gram-positive cocci were sensitive to linezolid, teicoplanin, and vancomycin and gram-negative bacteria were sensitive to meropenem, piperacillin/tazobactam, cefoperazone/sulbactam and cefepime. Conclusion: The present study concluded that the most common aerobic bacteria isolated from surgical site infection in our setting was found to be Staphylococcus aureus. This study also showed that the gram-positive aerobic bacteria were most susceptible tolinezolid, and teicoplanin, and gram-negative aerobic bacteria were sensitive to meropenem, piperacillin/tazobactam, and cefoperazone/sulbactam.