Kirby-Bauer Disc Diffusion Method Research Articles

Characterization of Leuconostoc lactis Bacteremia during a 2-year Study at a Tertiary Care Center in North India-An Observational Analysis.

Leuconostoc species are regarded as important causes for many infections in immunocompromised patients. In this study, we assessed the characteristics of Leuconostoc spp. causing bacteremia in patients at our center. This observational analysis was conducted in the microbiology laboratory of a tertiary care center in northern India from July 2021 to July 2023. Patients in whom blood culture bottles were positive for Leuconostoc lactis were included in the study. Culture isolates were identified by MALDI-ToF MS as L. lactis and tested for antibiotic sensitivity results by Kirby-Bauer disk diffusion method. Demographic and clinical details were collected and analyzed. During the study period, 6,742 blood culture bottles flagged positive. Among these, L. lactis was isolated from 14 (0.21%) patients. The median patient age was 34 years. The male-to-female ratio was 2.5:1. All the patients with L. lactis bacteremia had an underlying condition leading to immunosuppression (e.g., carcinoma and chronic kidney disease). All the patients with L. lactis bacteremia had an intravascular device present at the time of bacteremia. All isolates in the study were sensitive to doxycycline, high level gentamicin, minocycline, ampicillin-sulbactam, and linezolid. Mortality was attributed to bacteremia by L. lactis in five patients. Appropriate and timely identification of the Leuconostoc species is important for the clinician to tailor regimens for the patients.

The appropriateness of empirical antibiotic therapy in the management of symptomatic urinary tract infection patients-a cross-sectional study in Nairobi County, Kenya.

In low- and middle-income countries, symptomatic urinary tract infection (UTI) patients are often prescribed antibiotics without microbiological confirmation. UTIs caused by antibiotic-resistant bacteria are increasingly common, and this heightens the risk of empirical treatment failure. This study evaluates the appropriateness of empirical antibiotic therapy to UTI patients in Nairobi County, Kenya. A hospital-based, cross-sectional study was conducted in Nairobi County, Kenya, amongst symptomatic adult and child patients. UTI was defined as a monoculture growth with colony counts of ≥104 cfu/mL. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disc diffusion method. Empirical therapy was considered appropriate if the pathogen isolated was susceptible to the prescribed antibiotic and inappropriate if the pathogen was resistant to the prescribed antibiotic. A total of 552 participants were enrolled with a median age of 29 years (interquartile range: 24-36). The majority were female, 398 (72%). Of the 552, 274 (50%) received empirical antibiotic therapy, and 95/274 (35%) were confirmed to have UTI by culture. The antibiotics most frequently prescribed were fluoroquinolones [ciprofloxacin in 80 (30%) and levofloxacin 43 (16%)], amoxicillin-clavulanic acid in 48 (18%) and nitrofurantoin in 32 (12%). Amongst the 95 patients with bacteriological confirmation of UTI, 50 (53%) received appropriate empirical antibiotic therapy, whilst for 38 (40%) participants, the therapy was inappropriate. The complexity of appropriate empirical treatment for UTIs is compounded by high levels of resistance in UTI pathogens. Antimicrobial resistance surveillance strategies that could help in designing appropriate empirical regimens in resource constrained settings should be adopted for optimal empiric therapy.

Antibiotic Resistance and Inflammatory Response in Urology Infections Caused by E. coli: A Molecular and Clinical Investigation

Background: Urinary tract infections (UTIs) are a common condition resulting from bacterial invasion of the urinary system, which includes the kidneys, ureters, bladder, and urethra. These infections are particularly prevalent among females due to anatomical differences and hormonal factors. UTIs can range from uncomplicated cases, where there are no structural abnormalities, to more severe infections that may ascend to the kidneys, causing pyelonephritis. Methods: This study aimed to isolate and diagnose Escherichia coli (E. coli) bacteria in patients with UTIs, identify specific virulence genes, and assess the bacteria's resistance to various antibiotics. A total of 100 clinical samples were collected from patients with UTIs at the General Hospital of Homadiyah and Ahmed Maher from October 2021 to December 2022. Bacterial identification was performed using biochemical tests and polymerase chain reaction (PCR) techniques, while antibiotic sensitivity was assessed using the Kirby-Bauer disk diffusion method. Additionally, inflammatory markers (TNF-α, IL-6, and IL-8) were measured using ELISA. Results: E. coli was isolated in 56% of the samples, with the highest prevalence in patients aged 31-40 years. The antibiotic sensitivity test revealed varying levels of resistance, with the highest sensitivity observed to third-generation cephalosporins, particularly ceftriaxone (32.2% resistance). PCR analysis identified the presence of several virulence genes, including the Hly gene in 96.6% of isolates and the iha gene in 10% of isolates. Elevated levels of inflammatory markers were observed in patients with UTIs, indicating a strong immune response to bacterial infection. Conclusion: E. coli is a significant pathogen in UTIs, exhibiting considerable antibiotic resistance, particularly to first-generation cephalosporins. The presence of specific virulence genes correlates with the severity of infection. These findings underscore the need for targeted antibiotic therapy and the development of strategies to manage antibiotic resistance in UTIs.

Prevalence, antimicrobial susceptibility profiles and resistant gene identification of bovine subclinical mastitis pathogens in Bangladesh

Subclinical mastitis (SCM), a silent threat in the dairy sector of Bangladesh poses a significant economic impact and serves as a potential source of infection for healthy cows, hindering efforts to achieve milk self-sufficiency. Despite the importance of this issue, limited research has been conducted on mastitis in Sylhet region of Bangladesh. This study aimed to investigate the molecular prevalence, antimicrobial susceptibility profile and resistant genes detection on pathogens (Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) causing SCM. In a cross-sectional study utilizing convenience sampling, 325 milk samples were collected from apparently healthy dairy cows. Initially, SCM was detected using the modified Whiteside test (MWST) method. Suspected positive samples were then subjected to bacteriological culture and standard biochemical assays, followed by molecular identification through polymerase chain reaction (PCR). Finally, antimicrobial susceptibility testing was conducted on all PCR-positive samples using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar. In the Sylhet district, the prevalence of SCM was 64.92 % (211 out of 325) at the individual animal level and 82.69 % (43 out of 52) at the herd level. Among the SCM-positive animals, S.aureus was found in 31.75 % (67 out of 211) of cases, E.coli in 81.99 % (173 out of 211), and K.pneumoniae in 66.82 % (141 out of 211). K.pneumoniae had the highest prevalence at 60 % in Zakiganj, S.aureus at 45 % in Zakiganj, and E.coli at 72 % in Bishwanath Upazila. Extended spectrum beta lactamase (ESBL) genes blaTEM, blaOXA, blaCTX-M1,blaCTX-M2,MultiCaseDHA were identified. Additionally, antibiotic resistance genes tet(A), AAC(3)-iv, and Sul1 were also detected. The pathogens exhibited resistance to Penicillins (ampicillin, amoxicillin), Cephems (cefuroxime, ceftazidime), and Tetracyclines (tetracycline). However, all three bacteria were highly sensitive to meropenem, amikacin, gentamicin, ciprofloxacin, and sulfamethoxazole-trimethoprim. These findings highlight the critical need for targeted antimicrobial stewardship and effective control measures to mitigate the impact of SCM on dairy production and animal health in the Sylhet region of Bangladesh.

Assessment of change in antimicrobial susceptibility pattern of bacteria causing orthopaedic infections by sequential sampling: A prospective cohort study

BackgroundManagement of Orthopaedic wound infections often depend on isolation of bacteria species (spp.) and its subsequent antimicrobial susceptibility testing (AST). However, the susceptibility to antibiotics may change over time in the same bacterial spp. particularly after initiation of antibiotic therapy. Repeating AST through sequential sampling can be used for the early detection of changes in antimicrobial susceptibility pattern. However, the recommendations about the optimal frequency of repeat AST for same bacterial spp. isolates from same patient to detect the changes in susceptibility patterns are still not established. Furthermore, no prospective research is available to address the crucial issue. Thus, we aimed this study to evaluate the need of repeat AST through sequential samples from the same site. MethodsAST was performed on same bacterial spp. isolates from three sequential samples using Kirby-Bauer disc diffusion method. Considering day 1 as control/baseline, changes in antimicrobial susceptibility pattern was interpreted on two sequential instances (on day 3 and day5). Changes were categorized into favorable & unfavorable and major & minor change categories. ResultsThe overall change in antimicrobial susceptibility pattern was 28 % on instance 1(on day3) and 36.1 % at instance 2 (on day 5). Susceptible to resistance phenotypic change was 14.9 % at instance 1 and 9.2 % at instance 2.A higher percentage change per case in antimicrobial susceptibility pattern was observed at instance 2. Predominant changes were towards the direction of favorable antimicrobial susceptibility pattern. ConclusionThe risk of change in antimicrobial susceptibility potential was over 10 % at both the instances. Furthermore, it was higher at instance 2 i.e., at day5, therefore a repeat sequential antimicrobial susceptibility testing would be recommended at later instance.

Distribution Patterns and Antibiotic Resistance Profiles of Bacterial Pathogens Among Patients with Wound Infections in the Jiaxing Region from 2021 to 2023.

To systematically assess the distribution and antimicrobial susceptibility of pathogens in wound infections, and analyze risk factors associated with multidrug resistance (MDR). Retrospectively analyzing Jiaxing-region medical records between January 2021 and December 2023, we identified a cohort of 461 wound infection patients. Cultures were grown on various agars, with bacteria identified via Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. The antimicrobial susceptibility of the organisms were conducted by VITEK 2 system, Kirby-Bauer disk diffusion method and Epsilometer test. Statistical Package for the Social Sciences (SPSS) version 22 was used for statistical analysis. Multivariable logistic regression models were developed to pinpoint risk factors for multidrug-resistant organism (MDRO) infections and predict occurrences. From 461 patients, 549 bacterial pathogens were isolated, predominantly consisting of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, and Enterococcus faecalis. Vancomycin, linezolid, and tigecycline maintained their efficacy against Staphylococcus aureus and Enterococcus species, while Pseudomonas aeruginosa demonstrated sensitivity to aminoglycosides. Conversely, Escherichia coli exhibited high amoxicillin resistance (85.4%). More than half of the isolates were resistant to levofloxacin, ceftriaxone, cotrimoxazole, and gentamicin, with Acinetobacter baumannii strains showing considerable resistance (65.8-68.4%) to advanced cephalosporins and carbapenems. Within this group, 58 MDROs were detected, primarily originating from Burn Plastic Surgery, Emergency, and Intensive Care Unit (ICU) departments. Multivariate logistic regression identified hyperglycemia, hypoalbuminemia, surgery, extended hospitalization, and exposure to multiple antibiotic classes as independent risk factors for MDRO wound infections. Based on these findings, a predictive model for MDRO occurrence in wounds was constructed, which had a sensitivity of 0.627, specificity of 0.933, and an Area Under the Curve (AUC) of 0.838. Staphylococcus aureus and Pseudomonas aeruginosa dominated in wound infections with differential antibiotic resistance. Independent risk factors included hyperglycemia, hypoalbuminemia, surgery, extended hospitalization, and polyantibiotic use. We urge prioritizing culture, susceptibility tests, and personalized antibiotic strategies to address MDRO risks and improve wound infection management specificity and efficacy.

Antimicrobial resistance pattern of Helicobacter pylori in patients evaluated for dyspeptic symptoms in North-Eastern India with focus on detection of clarithromycin resistance conferring point mutations A2143G and A2142G within bacterial 23S rRNA gene

PurposeIn India there is evidence of antimicrobial resistance in Helicobacter pylori, a definitive pathobiont whose only known niche is human gastric mucosa. This in turn can lead to failure of treatment, persistence or chronicity of infection. This hospital based, prospective, observational study investigates the presence of antimicrobial resistance in the organism with focus on detection of A2143G and A2142G major point mutations in domain V of H. pylori 23S rRNA gene as a molecular mechanism of conferring resistance. MethodsEndoscopic gastric biopsy samples from 52 patients presenting with dyspeptic symptoms from January 2016 to December 2016 were subjected to culture in a microaerophilic environment using Campylobacter agar with for 2–5 days. Isolates were identified using gram-staining, motility test and biochemical reactions. Modified Kirby-Bauer Disc diffusion method was used to determine antimicrobial susceptibility against Clarithromycin, Metronidazole, Amoxycillin, Levofloxacin, Tetracycline, Cotrimoxazole and Erythromycin. Additionally, detection of A2143G and A2142G point mutations conferring Clarithromycin resistance was carried out using real time PCR following extraction and quantification of bacterial DNA. Histopathological examination was carried out on all biopsy samples. Descriptive and inferential statistical analytical methods were used. Differences were considered significant for p < 0.05. ResultsCulture positivity for H. pylori by phenotypic method was found to be 36.54%. Histopathologic Examination detected H. pylori in 55.7% and PCR detected 48.08% for either the wild type or one of two mutant strains A2143G and A2142G. No sample was found positive for both mutations. Metronidazole showed the highest resistance among antibiotics (78.9%) followed by Clarithromycin (47.3%). ConclusionPrevalence of antimicrobial resistance in H. pylori in North-Eastern India is substantially high with A2143G mutation being clinically most important in conferring Clarithromycin resistance. This resistance might be associated with low eradication rates despite initiation of therapy. ROC analysis of PCR proved it to be a good diagnostic tool.

Evolution of copper coupons resistance in Enterobacteriaceae strains isolated from high-contact surfaces in hospital.

Metallic copper alloys have gained attention recently as a cutting-edge antibacterial weapon for areas where surface hygiene is crucial. The present study aimed to assess copper coupons (99% Cu) for their potential to decrease the viability of various Enterobacteriaceae strains from inanimate hospital surfaces. This in vitro-experimental study was conducted at the Microbiology Laboratory, Faculty of Natural and Life Sciences and Earth and Universe Sciences, University of Guelma, and Khodja Ahmed Public Hospital Establishment, Algeria, for a period of six months from January to May 2022. A total of 85 samples were collected from patient room door handles and bed rails at the government hospital in Guelma State, from which 12 enterobacterial isolates were obtained. These isolates were evaluated for susceptibility to copper and polyvinyl chloride (PVC) coupons using plate counts to determine bacterial viability after 72 hours of incubation at 37°C or room temperature (25°C). Antibiotic sensitivity testing was then carried out using a modified Kirby-Bauer disc diffusion method. Copper coupons' ability to either select for or create antibiotic resistance is also determined. Copper showed a bactericidal effect after three hours for Serratia odorifera and six hours for Escherichia coli. Whereas it was shown that within three days of selection, 83.33% of Enterobacteriaceae strains are capable of rapidly acquiring Cu resistance. Indeed, the increase in temperature reduced the effects of Cu (p<0.05; Student's t-test). Antimicrobial susceptibility testing revealed that the copper-resistant bacteria were less sensitive than their predecessors. Citrobacter freundii strains showed the highest incidence of multidrug resistance. The most significant findings included widespread resistance to beta-lactams (100%-75%) and chloramphenicol (66.67%). These results suggest that prolonged copper usage may contribute to the development of antibiotic resistance, which could have significant ramifications.

Prevalence and antimicrobial resistance of salmonellae isolated from eggs of local chicken in selected towns of Ethiopia.

Salmonellosis is one of the most common food-borne diseases in industrialised and developing countries. In recent year, an increase in antimicrobial resistance among different Salmonella serotypes has been observed. A cross-sectional study was conducted to assess the prevalence and antimicrobial susceptibility of Salmonella isolated from local chicken eggs in four selected towns in Ethiopia. A total of 115 eggs were examined to detect Salmonella by using standard microbiological methods. The susceptibilities of the isolates to nine antimicrobials were tested by the Kirby-Bauer disk diffusion method. The study revealed that of the 115 eggs examined, 22 (19.1%) were positive for Salmonella of which 14 (12.2%) and 8 (7%) of the isolates were from shells and contents, respectively. The occurrence of Salmonella in egg shells and content and between different altitudes did not differ significantly (p > 0.05). Most isolates were resistant to more than three antimicrobials with a high resistance to kanamycin, ampicillin, nalidixic acid, cotrimoxazole, oxytetracycline and chloramphenicol. The results indicate the potential importance of local chicken eggs as source of multiple antimicrobial-resistant salmonellae and the need for proper cooking before consumption. Further studies are required to describe the epidemiology of Salmonella in various agroclimatic zones of Ethiopia.

Tapping into the Power of Sol-Gel Method for Enhanced Antimicrobial Activity of Titania Nanoparticles

Increasing bacterial resistance to antibiotics has become a serious threat to global public health. In this context, this study aims to evaluate the antimicrobial activity of titanium dioxide nanoparticles (TiO2 NPS) synthesized using the sol-gel method. TiO2 NPS samples were prepared and characterized for morphology via field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. Kirby-Bauer disc diffusion method was used to test the antimicrobial activity of TiO2 NPS against Gram positive bacteria Staphylococcus aureus, Gram negative bacteria Escherichia coli, and pathogenic fungus Aspergillus penicillioides. The results showed that TiO2 NPS effectively inhibited the growth of microorganisms, with significant inhibition zones especially against fungi. The antimicrobial mechanism of TiO2 NPS involves the formation of hydroxyl radicals and superoxide ions that damage the cell membrane of microorganisms. The implications of this study are the development of potential antimicrobial nanomaterials for biomedical and environmental applications, as well as the importance of considering the physical and chemical properties of TiO2 NPS in designing effective infection treatment strategies.

Association between the biofilm formation of streptococcus mutans, dental caries experience, and resistance to antibiotics in adult patients

Objectives: The aim of this study was to consider the potential association between the formation of bucall mucusa streptococcus biofilms and a high DMFT index, as well as the occurrence of antibiotic resistance among adult patients in Sana'a, Yemen. Study design: A total of 100; 34-85 year old. Clinical examinations of patients were performed to estimate dental caries experience with the Silness-Loe index, as well as bucall mucusa swabs were collected to assess biofilm production by the phenotypic method, i.e., tissue culture palate methods (TCPM). Finally, the antibiogram susceptibility pattern of isolated S. mutans was done by the Kirby-Bauer disc diffusion method for L-Lactam antibiotics (as ampicillin and penicillin) and non-L-Lactam antibiotics (clindamycin, erythromycin, lincomycin, and vancomycin). Results: When isolated S. mutans were exposed to biofilm detection by the TCP method, 1 (1.2%) showed strong biofilm formation capacity, 71 (86.6%) showed moderate biofilm formation capacity, and 10 (12.2%) showed non/weak formation capacity of biofilm. There was an escalation in the rate of formation of S. mutans biofilms with an increased degree of caries index. The S. mutans biofilms positively showed a higher rate of resistance than non/weak biofilm formation, e.g., ampicillin (91.1% versus 8.9%, p &lt;0x7E&gt; 0.0001), tetracycline (87.8% versus 12.2%, p &lt;0x7E&gt; 0.0001), and co-trimoxazole (90%% versus 10%, p &lt;0x7E&gt; 0.0001), etc. Conclusion: The present study proved that S. mutans is still the major bacteria isolated from the oral cavity, but few persons might not have a significant number of S. mutans in the oral cavity. The S. mutans biofilm producers were more able to cause dental caries compared to the S. mutans biofilm non-producers. Drug-resistant factor in the S. mutans isolates was found to be associated with S. mutans biofilm formation.

Antibacterial Activity of Methanol Extract of Salvadora Persica (Linn) Stem against Gram-Positive Bacteria Isolated from Oral Infections among the Patients Attending the University Health Clinic of Ahmadu Bello University Zaria

Study’s Novelty/Excerpt This study presents detailed evaluation of the methanol crude extract of Salvadora persica L. (Miswak) for antibacterial effectiveness specifically against gram-positive bacteria from orally infected individuals. It highlights a significant therapeutic efficacy of the extract, evidenced by inhibition zones of 18-22 mm and a minimum inhibitory concentration (MIC) of 25 mg/ml, against pathogens with high resistance rates to conventional antibiotics. Additionally, the research provides comprehensive phytochemical profiling of S. persica, contributing valuable insights into its potential as an alternative treatment for oral infections. Full Abstract Salvadora persica L., commonly referred to as Miswak, is a chewing stick commonly used to maintain dental hygiene. The aim was to determine the antibacterial effectiveness of the methanol crude extract of S. persica against gram-positive bacteria obtained from orally infected individuals who were registered at the University Health Clinic of Ahmadu Bello University. A total of twenty (20) samples were collected from patients who were diagnosed with oral infections. These samples underwent traditional biochemical and microbiological testing. The antibiotic susceptibility test was conducted using the Kirby-Bauer disc diffusion method, and the findings were interpreted following the CLSI standards. The extraction of Salvadora persica L. was carried out using cold maceration with methanol. The crude extract was evaluated using the agar well diffusion and broth dilution techniques. Phytochemical screens were conducted using established procedures. The findings revealed that Staphylococcus aureus had the highest prevalence rate of 60%, whereas Streptococcus sp. had a prevalence rate of 10%. A high level of resistance was detected for amoxicillin (100%), chloramphenicol (85%), ciprofloxacin (60%), ceftriaxone (50%), and gentamycin (47.5%). The cold maceration extraction process yielded in % crude extract yield of 11.59%. The phytochemical elements were saponin, tannin, alkaloid, flavonoid, phenol, heart glycoside, carbohydrate, steroid, and terpenoid. An area of inhibition measuring 18-22mm and a minimum inhibitory concentration (MIC) of 25mg/ml were employed to detect a significant degree of activity. The methanolic extract of Salvadora persica L. has shown significant therapeutic efficacy against gram-positive bacteria recovered from orally infected patients.

Melissa officinalis Extract as an Antimicrobial Agent Against Clinical Bacterial Strains Isolated from Urinary Tract Infections in Najaf, Iraq

Background: Antibiotics are used to inhibit the growth of bacterial infections. However, antibiotic resistance is increasing due to their use. Plant extracts are natural compounds with unique medical properties. The current study investigated the effect of Melissa officinalis collected from Marivan, Iran, against urinary tract infection (UTI). Methods: The plant extract was prepared using the Soxhlet method. The bacterial strains were isolated from UTI patients at AlZahra Hospital in Najaf, Iraq. The antibacterial activity of M. officinalis extract was evaluated using the Kirby-Bauer disk diffusion method. The minimal inhibitory concentration (MIC) was also determined by the microdilution method. Results: According to the inhibition zone results, M. officinalis greatly affected Staphylococcus aureus, Proteus vulgaris, and Klebsiella pneumoniae. The plant extract showed the highest antimicrobial activity on the standard and clinical strains of S. aureus with the highest inhibition zone record of 8.4±0.163 and 9±0.0 mm and MIC of 0.09 and 0.06 mg/mL, respectively. Also, M. officinalis extract indicated an antimicrobial effect against the standard and clinical strains of K. pneumoniae with the highest inhibition zone record of 8±0.0 and 9±0.0 mm and MIC of 0.06 and 0.06 mg/mL, respectively. Furthermore, the plant extract showed the most antimicrobial activity on the standard and clinical strains of P. vulgaris, with the highest records of 7.9±0.23 and 9±0.0 mm and MICs of 0.14 and 0.06 mg/mL, respectively. Conclusion: Melissa officinalis extract can be a suitable candidate as an alternative to antibiotics for treating UTIs.

Antibacterial Susceptibility Pattern of Bacteria Isolated from Ready-to-Eat Lettuce and Gurasa Sold within Kaduna State University (Main Campus), Kaduna State

Study’s Novelty/Excerpt This study evaluates the antibacterial susceptibility of pathogens isolated from ready-to-eat lettuce and gurasa sold at Kaduna State University, identifying significant health risks associated with these popular foods. The research reveals a high prevalence of antibiotic-resistant bacteria, including Staphylococcus aureus, Escherichia coli, Bacillus spp, Salmonella spp, and Klebsiella spp, with S. aureus and E. coli being the most common isolates. The findings highlight the urgent need for improved food safety measures and antibiotic resistance management to mitigate potential public health threats. Full Abstract The consumption of ready-to-eat lettuce and gurasa has gained acceptance due to its appealing taste and nutritional value. However, these foods can serve as a vehicle for transmission of pathogens. This study was carried out to assess the antibacterial susceptibility pattern of pathogens isolated from lettuce and gurasa sold at Kaduna State University. Samples were collected from five vendors of gurasa and lettuce. Standard microbiological methods were carried out using a pour plate and a modified Kirby-Bauer disc diffusion method to determine the antibacterial susceptibility pattern. The isolates obtained were examined for morphological and biochemical characteristics. Escherichia coli, Bacillus spp, Salmonella spp, Staphylococcus aureus, and Klebsiella spp. were isolated and identified. Staphylococcus aureus was the most prevalent bacterium in this study, having 27.7% in lettuce and 38.4% in gurasa, and Escherichia coli, having 16.6% in lettuce and 30.7% in gurasa. There was no significant difference (P ˃ 0.05) in the total colony counts of bacteria among the samples. Lettuce had the least bacteria count (1.48 x 106 CFU/g), while gurasa had the highest (1.55 x 106 CFU/g). Antimicrobial sensitivity test results showed that 10 S. aureus isolates were resistant to Rocephin (100%), 7 E. coli isolates were resistant to Septrin, Amoxicillin, and Augmentin (100%), 6 Klebsiella spp isolates were resistant to Amoxicillin and Augmentin(100%), 5 Salmonella spp isolates were resistant to Septrin, Amoxicillin and Augmentin (100%) and 3 Bacillus spp were resistant to Rocephin (100%). The high bacterial resistance to antibiotics is of great concern as infections with these organisms could be lethal.

Synergistic Effect of Combination Antibiotics against Multidrug-Resistant Salmonella enterica serovar Typhi

Background: Infection caused by multidrug-resistant (MDR) Salmonella enterica serovar Typhi (S. Typhi) is a major health problem in low- and middle-income countries (LMICs). S. Typhi has been reported to be resistant to fluoroquinolones and cephalosporins. Objective: To find out the anti-microbial activity of combination antibiotics against resistant S. typhi. Materials and Methods: First, single antibiotic disks of ciprofloxacin, imipenem and vancomycin with the concentrations of 20, 40, 60 and 80 μg/ml were prepared and applied against sensitive S. typhi to confirm its susceptibility. Later, a resistant strain of Shigella flexneri was treated with single antibiotic (ciprofloxacin, vancomycin and imipenem) at the highest concentration (80 μg/ml) to determinets resistant behavior by measuring the zones of inhibition obtained from the disc diffusion assay. Co-culture was performed between the sensitive and resistant strains to develop the resistant strain of S. typhi. Combinations of antibiotics were used for susceptibility testing against the newly resistant strain of S. typhi by using Kirby–Bauer disk diffusion method. Experiments were carried out in triplicates and the average reading was recorded. Results: The study showed that different concentrations of the combination of vancomycin and imipenem (20, 40, 60, 80 μg/ml) exhibited 18, 20, 24- and 29-mm respective zone of inhibition (ZOI) against S. typhi. A combination of ciprofloxacin and imipenem also exhibited optimum ZOI. It was observed in this study that a single antibiotic treatment did not show any activity against newly resistant strains of S. typhi. Conclusions: The combination therapy can be used as a beneficial treatment approach in multi-drug resistant S. typhi infections. Dhaka Univ. J. Pharm. Sci. 23(1): 37-42, 2024 (June)

Investigation of prevalence and antimicrobial resistance of Salmonella in pet dogs and cats in Turkey.

Although salmonellosis is considered to be a foodborne zoonotic disease, pets can play a significant role in the dissemination of antimicrobial-resistant Salmonella organisms to humans because of close contact with their owners. To determine the prevalence, risk factors, virulence factors, serotypes, and antimicrobial resistance profile of Salmonella in pet dogs and cats in Turkey and to assess the public health risk. Furthermore, to perform macroscopic comparison of lactic acid bacteria (LAB) in Salmonella-positive and Salmonella-negative animals. International Standards Organization (ISO) 6579-1:2017 and Food and Drug Administration (FDA) methods were used to compare the effectiveness of culture methods in the identification of Salmonella in 348 rectal swabs. Positive isolates were serotyped using the slide agglutination method according to the White-Kauffmann-Le Minor scheme and the presence of virulence genes (invA and stn) were evaluated by polymerase chain reaction (PCR). Antimicrobial activity was tested by Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Salmonella prevalence was 5.73% (9/157) in dogs and 0.0% (0/191) in cats. Eight (8/9) isolates were cultured with the ISO method and 5 (5/9) isolates were cultured with the FDA method. Macroscopic results revealed that Salmonella agents had no effect on LAB. Three different serotypes were detected and all isolates were positive for virulence genes. Antibiotic resistance profiling indicated that 11.1% of the isolates were MDR and the highest resistance was found for ciprofloxacin. MDR-resistant S. Virchow and carbapenem-resistant S. Enteritidis were detected from dog isolates. There was a significant difference between raw meat consumption and Salmonella carriage (p < 0.01). Dogs could be potential carriers of Salmonella infection. The isolation of Salmonella in healthy dogs instead of dogs suffering from diarrhoea indicates that attention should be paid to asymptomatic carriage. The emergence of resistance among zoonotic Salmonella isolates poses a significant threat to public health.

ANTIMICROBIAL EFFECT OF CLOVES (Syzygium aromaticum) ON Escherichia coli FROM FEMALE ADULTS URINE WITHIN ALUU COMMUNITY, RIVERS STATE, NIGERIA.

The study was aimed at determining the antimicrobial effect of clove on Escherichia coli isolated from the urine of female adults in Aluu community, Rivers State. Clean-void, mid-stream urine (MSU) specimens were collected from 30 female adults and 20 pregnant women residing in Aluu community, Port Harcourt Rivers state. The samples were culture on Eosin Methylene Blue (EMB) agar by streaking method. Biochemical test was carried out on the isolated bacteria using Bergey’s Manual of Bacteriological Identification. Antibiogram of the isolated bacteria were determined by Kirby-Bauer disc diffusion method. Antimicrobial activity of clove extract was determined by well-in-agar method. Among the 30 sample of the adult female, only 20% of the urine sample were positive for the presence of Escherichia coli while 80% were devoid of Escherichia coli. In the case of urine sample from pregnant women, Escherichia coli was isolated from 45% of the sample while 55% of the sample showed no presence of Escherichia coli. The result of the antibiotic sensitivity showed that 14% of Escherichia coli were resistant to ofloxacin, 33% resistant to perfloxacin, 60%, resistant to augmentin, 74% resistant to nitrofurantoin, 73%, resistant to ceftazidime, 93% resistant to Nalidixic acid and 33% were resistant to gentamin. The antimicrobial activity of cloves produced zone inhibition ranged from 11.50±0.71 to 17.50±0.71mm of all the tested isolated. The antimicrobial potential of clove in the treatment of urinary tract infection by Escherichia coli was also shown in this study, hence could be applied in the treatment of urinary tract infections.

A Quick, High-Yield Biogenic Synthesis of Antibacterial AgNPs (Silver Nanoparticles) via Carica papaya Seeds

Carica papaya seeds were used in this research for the synthesis of AgNPs. The production of silver nanoparticles was characterized using UV–Vis spectroscopy, FTIR, XRD and SEM-EDX analysis. The antibacterial activity of the prepared AgNPs was evaluated by the Kirby–Bauer disc diffusion method with the antibacterial activity of different compounds against Bacillus aerogenes. UV–Vis spectral peaks are found at 8–18 nm. SEM and TEM analysis revealed several spherical structures between 10 nm and 50 nm. XRD analysis also confirmed its 50 nm size. Experimental data revealed that AgNPs inhibited bacterial growth. This study shows that papaya seed extract contributes to the bioreduction and stabilization of the synthesized silver nanoparticles.

Multidrug Resistance And Susceptibility Profile of Outpatient Escherichia Coli Clinical Isolates

Background: To gain better understanding about the impact of antibiotic selection pressure on antimicrobial resistance (AMR) in Nigeria, it is important to conduct and review from time to time the susceptibility profile of clinically important bacteria including Escherichia coli. This study investigated the susceptibility and multidrug resistance profile of E. coli isolates from urine samples of patients who received outpatient’s medical services in Abakaliki. Methods: A total of 50 non-duplicate clinical isolates of E. coli from the microbiology laboratory section of a tertiary hospital in Abakaliki, Nigeria was recruited for this study. Susceptibility studies were determined using amoxicillin (20 µg), ceftazidime (30 µg), ciprofloxacin (5 µg), gentamicin (10 µg), nitrofurantoin (300 µg) and erythromycin acid (15 µg) by the modified Kirby–Bauer disk diffusion method. All susceptibility studies were carried out as per the guidelines of the Clinical Laboratory Standard Institute (CLSI). Multidrug resistance was evaluated by the multiple antibiotic resistance index (MARI) calculation. Results: The E. coli isolates showed reduced susceptibility to gentamicin (75%), ciprofloxacin (85%), nitrofurantoin (95%), amoxicillin (100%), erythromycin (100%) and ceftazidime (95%). A total of 12 E. coli isolates were multidrug resistant to clinically important antibiotics in the classes: cephalosporins, macrolides, aminoglycosides, fluoroquinolones, penicillins and nitrofurantoin. Conclusion: We report a high rate of antibiotic resistance of outpatients E. coli isolates which concurrently showed multidrug resistance to important antibiotic classes. These findings have clinical significance and provide a benchmark for future studies on the susceptibility pattern of clinical isolates in Nigeria. This preliminary study reiterates the need to reinvigorate antibiotic stewardship in our local hospitals so as to preserve the clinical efficacy of available antibiotics since it takes years for a new antibiotic to be developed.

In vitro antimicrobial activity of silver nanoparticles against selected Gram-negative and Gram-positive pathogens.

Infections caused by pathogenic bacteria increase patient morbidity and mortality and significantly raise treatment costs. The use of silver nanoparticles as an alternative treatment for S aureus, E coli, MRSA, E faecalis, K pneumoniae and P aeruginosa indicates their antibacterial effect and prompts medical research to consider the next generation of antibacterial drugs that could change antibiotic therapy. By combining silver nanoparticles with different classes of antibiotics, the antibacterial effect is evidenced by increased values of the inhibition zone compared to the values obtained for some antibiotics commonly used in the treatment of bacterial infections. This study focuses on comparing the antibacterial activity of antibiotics versus antibiotics combined with silver nanoparticles against various bacteria, by comparing inhibition zones obtained for both. We aim to prove that the size of the inhibition zone for antibiotics combined with silver nanoparticles is greater, thus confirming the improved antibacterial effect. In this study we tested the antibacterial activity of solutions of silver nanoparticles alone or in combination with different antibiotics. We used standard bacterial strains, ATCC, both Gram positive bacteria Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, as well as Gram negative bacteria Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, but also on clinical isolates: a strain MRSA (Methicillin Resistant Staphylococcus aureus) and a PDR strain (pan drug resistant) of Klebsiella pneumoniae. Bacterial identification was performed using Vitek MS analyzer (bioMerieux). Antibiotic susceptibility determination was performed with VITEK2 COMPACT SYSTEM (bio Merieux, Inc Durham NC) with ready to use VITEK AST cards. The interpretation of the results was done in compliance with EUCAST 2023-2024 standards. Testing was performed for several classes of antibiotics, silver nanoparticle solutions in 2 concentrations (10 μg/mL and 100 μg/mL) and for combinations of antibiotics with silver nanoparticle solutions. The diameter of the inhibition zone (ZOI) for silver nanoparticles, antibiotics and silver nanoparticles combined with antibiotic against each bacterium was expressed in millimeters. The Kirby-Bauer disk-diffusion method, in accordance with current EUCAST standards, was used to analyze the antibacterial effect of antibiotics, silver nanoparticles, and antibiotics combined with silver nanoparticles at biocompatible doses of 10 and 100 μg/mL. The experiments were conducted in triplicate, and the results were almost identical. The results of this study show that the silver nanoparticles displayed antibacterial activity, proven by the appearance of the inhibition zone, in various sizes, for all bacteria studied. The antibiotic classes tested were beta-lactamins, first, second, third and fourth generation cephalosporins, macrolides, fluoroquinolones, lincosamides, aminoglycosides, glycopeptides, tetracyclines, oxazolidinones, sulfonamides, rifamycins, amphenicols. Testing S aureus ATCC 29213, the highest zone of inhibition was demonstrated for cephalosporins (32.6667 ± 0.701 mm), macrolides (31.6667 ± 0.701 mm, and lincosamides (29.6667 ± 0.701 mm). Testing MRSA (internal code GR0333), the highest zone of inhibition for combination of silver nanoparticles and antibiotics was demonstrated for fluoroquinolones (36.3333 ± 0.701 mm), lincosamides (32.3333 ± 0.701 mm), Fusid acid (32.3333 ± 0.701 mm) and aminoglicosides (31.3333 ± 0.701 mm). Testing E coli ATCC 25922 the highest zone of inhibition was for Fosfomycine, 39 mm and for E faecalis ATCC 29212 for aminoglicosides was 19 mm. For K pneumoniae (internal code GQ8575) the inhibition zone for silver nanoparticles 100 μg/mL was 12.3333 ± 0.701 mm and for P aeruginosa ATCC 27253 was 16 ± 1.214 mm. The use of metallic nanoparticles, especially silver ones, as antimicrobial agents with definite bactericidal activity has led medical specialists to consider this new treatment which may change antibacterial therapy. Studies of in vitro combinations between silver nanoparticles and different classes of antibiotics represent a highly efficient and effective new antibacterial treatment against multidrug-resistant bacteria. To avoid the problem of antimicrobial resistance associated with conventional antibiotics, it is necessary to understand the adaptive mechanisms of bacteria under the action of metal nanoparticles, which could be exploited in future studies. Further in vitro and in vivo studies that would assess specify the biocompatibility and toxicity of silver nanoparticles will make these super nanomaterials the medicines of the future.