Standard Disk Diffusion Method Research Articles

Susceptibility patterns of Escherichia coli and streptococcal isolates from bovine mastitis cases to antibiotics and selected South African plant extracts with known antibacterial activities

Bovine mastitis, an inflammatory condition affecting the mammary glands of dairy cattle, poses a significant economic burden on the dairy industry. Staphylococcus species, Streptococcus species and Escherichia coli are common pathogens. Managing mastitis typically involves antibiotics, but antimicrobial resistance (AMR) is a growing concern, promoting further research exploring alternative treatments including plant extracts. This study aimed to determine the antibiotic resistance of E. coli and streptococcal isolates from mastitis cases, and to investigate four indigenous South African plants for their selective antibacterial activities against these pathogens. The antimicrobial susceptibility of the bacterial strains was determined using a standard disc diffusion method. Minimum inhibitory concentration (MIC) values of acetone and ethanol extracts of Searsia lancea, Indigofera frutescens, Erythrina caffra and Antidesma venosum were determined against the bacterial isolates using a serial microdilution assay, and cytotoxicity was also investigated. The results showed that 82.14% of the clinical isolates tested were resistant to at least one antimicrobial agent used, and 52.17% of the antibiotic resistant isolates were multidrug resistant. All plant extracts had antibacterial activity against all the bacterial isolates, but S. lancea demonstrated higher efficacy compared to other plants. The MIC values ranged from 0.01 to 2.50 mg/mL, with the lowest range obtained with the acetone extract of S. lancea (0.01 to 0.57 mg/mL). Furthermore, the extracts were relatively non-cytotoxic to bovine dermis and Vero cells, with the highest mean selectivity index value of 25.70 recorded with S. lancea. This study highlights the growing concern of AMR in livestock management, and demonstrates the promising therapeutic potential of the selected plant species, particularly S. lancea, in treating bovine mastitis. Further exploration of S. lancea is recommended to develop novel alternative or complementary formulations for mastitis management.

Anti-bacterial activity of essential oils against multidrug-resistant foodborne pathogens isolated from raw milk.

The presence of pathogenic bacteria in food is considered as a primary cause of food-borne illness and food quality deterioration worldwide. The present study aimed to determine the effectiveness of five essential oils (EOs) against multidrug-resistant foodborne pathogens. In the current study Gram-negative bacteria (Escherichia, Enterobacter, Citrobacter, Proteus, Pseudomonas, and Klebsiella) and the Gram-positive bacteria Staphylococcus were isolated from raw milk and biochemically characterized. The anti-bacterial effect of different antibiotics and EOs (thyme, oregano, lemongrass, mint, and rosemary) was determined using the standard disc diffusion method. The antibiogram study revealed that Gram-negative bacteria were highly resistant to penicillin while Staphylococcus was resistant to streptomycin, amoxicillin, and lincomycin. Moderate resistance was observed to doxycycline, amikacin, enrofloxacin, kanamycin and cefixime. Isolates were found less resistant to gentamycin, chloramphenicol, and ciprofloxacin. EOs showed a broad range of antimicrobial activity against all bacteria except P. aeruginosa. Of these, thyme was more effective against most of the multi-drug resistant bacterial strains and formed the largest zone of inhibition (26 mm) against Escherichia followed by oregano oil (18 mm) against Staphylococcus (p<0.05). Klebsiella spp and Citrobacter spp showed resistance to mint and lemongrass oil respectively. The EOs such as lemongrass, mint and rosemary were less active against all the bacteria. The findings of the recent study suggest the use of EOs as natural antibacterial agents for food preservation.

Antimicrobial susceptibility pattern of bacteria isolated from patients with Otitis externa attending a tertiary health-care institution in Sokoto, Nigeria

Abstract Background: Otitis externa is the inflammation or infection of the skin of the external auditory canal, may be acute, subacute, or chronic and usually manifests by itching of the ear, otalgia, otorrhoea, aural fullness, and hearing loss. The causative agent is usually bacteria and occasionally fungi but may be associated with a variety of noninfective systemic or local dermatological conditions such as eczema, seborrhea, and contact dermatitis. Aim: This study aimed to determine the risk factors, bacterial profile, and antimicrobial susceptibility pattern of the isolates from patients with Otitis externa. Methods: A descriptive cross-sectional hospital-based study was conducted on 100 patients with Otitis externa. The ear discharge specimens were collected and analyzed by standard microbial techniques. The antibiotic susceptibility profiles were determined for 12 different antibiotics by the standard disk diffusion method. Data were analyzed with SPSS version 25 and the P &lt; 0.05 was considered statistically significant. Results: The age of the 100 participants ranges from 4 to 57 years with a mean age of 18.78 ± 10.67 standard deviation, and the commonly affected age group was 11–20 years. Pathogens were isolated from 77 (62.1%) of the patients. The predominant isolate was Pseudomonas aeruginosa 32 (41.6%), followed by Staphylococcus aureus 13 (16.9%), others include Proteus mirabilis 7 (9.0%), Peptostreptococcus species 5 (6.5%), Escherichia coli 4 (5.2%), Streptococcus pneumonia 4 (5.2%), Klebsiella pneumonia 3 (3.9%), Streptococcus pyogenes 3 (3.9%), Enterobacter aerogenes 2 (2.6%), Fusobacterium species 2 (2.6%), and Bacteroides 2 (2.6%). Ofloxacin showed good susceptibility to isolated aerobes 65 (95.6%), followed by gentamicin 52 (76.5%) and ceftriaxone 50 (73.5%). All isolated anaerobes showed 100% susceptibility to metronidazole and clindamycin. Bacterial isolates identified in this study showed a trend of multiple drug susceptibility, majority (70%) being susceptible to three or more antimicrobials. Conclusions: Majority of the bacterial isolates were susceptible to more than one antimicrobial agent, hence efforts to isolate microorganisms and determine the susceptibility pattern should be strengthened to improve the treatment outcome of Otitis externa instead of the usual trend of empirical treatment.

Evaluation of the LifeScale system for rapid phenotypic antimicrobial susceptibility testing from positive blood cultures

Abstract Objective The spread of antimicrobial resistance is a growing threat to public health, thus there is a critical need for prompt and reliable antimicrobial susceptibility testing (AST). Rapid AST may improve patient outcomes by allowing for quicker start of optimal therapy and reducing hospital length of stay, therefore decreasing overall healthcare costs. However, rapid results may not improve patient care if they are not considered equivalent to standard AST. Several platforms are under development that can provide rapid AST results; the objective of this work is to assess the performance of the new LifeScale rapid AST platform (Affinity Biosensors) that uses resonant mass measurements for calculation of antimicrobial susceptibility results. Methods Positive BACTEC blood-cultures collected from patients were included if the gram stain revealed only Gram-negative rods. Standard of care (SOC) AST results, as determined by a combination of BD Phoenix automated, Sensititre broth microdilution, and/or standard disk diffusion methods, were compared to results from direct positive blood culture testing on the LifeScale system. Minimum inhibitory concentrations (MICs) and categorical interpretations based on CLSI and/or FDA AST breakpoints were compared by microorganism and drug to calculate essential and categorical agreement for five species with pending claims on the LifeScale system: Escherichia coli (N=33), Klebsiella pneumoniae (N=10), K. oxytoca (N=5), Pseudomonas aeruginosa (N=11) and Acinetobacter sp. (N=1); tested against 13 relevant antibiotics: Amikacin, ampicillin, aztreonam, cefazolin, cefepime, ceftazidime, ceftazidime/avibactam ertapenem, gentamicin, levofloxacin, meropenem, piperacillin/tazobactam, and trimethoprim/sulfamethoxazole. Results LifeScale had 95.3% essential agreement with the SOC results, and a 93.1% categorical agreement based on CLSI M52 criteria. Of the 665 organism-drug combinations evaluated, agreement was high, with only 1 very major discrepancy, 8 major discrepancies and 37 minor discrepancies, of which 22 (47.8%) were within ±1 doubling dilution. Among these discrepancies, LifeScale MICs averaged 1 dilution higher than SOC MICs, which may reduce the risk of false-susceptible interpretations. Conclusion s: The accuracy and reliability of results from rapid AST is of utmost importance. The LifeScale technology is unique among AST platforms as it measures bacterial cell mass and counts to determine MICs for up to 14 antibiotics in ~4 h. These results suggest this platform is able to deliver rapid, actionable results to guide antimicrobial therapy for patients with bacteremia.

Detection of virulence genes and multidrug resistance in Pseudomonas aeruginosa clinical isolates from a public hospital in Lagos, Nigeria

Pseudomonas aeruginosa is a main cause of nosocomial infections and is classified as a priority critical pathogen of global concern. Multidrug resistance and virulence genes attributed to the pathogenicity of the organism has resulted in failed therapies, linked to increased morbidity and mortality in infected patients. The aim of this study was to determine the virulence genes and multidrug resistant P.aeruginosa in clinical specimens from a secondary health care center laboratory in Lagos, Nigeria. MethodologyA total of three hundred and sixty-seven clinical samples were examined with conventional methods and Microbact GNB12A. Forty- seven (47) P. aeruginosa strains were identified. Antimicrobial susceptibility test was performed by the standard disk diffusion method following CLSI guidelines. Identification of P. aeruginosa was done by amplification of oprL and oprI genes. Monoplex and multiplex PCR assays were used for detecting virulence genes (lasB, toxA, exoU and nan1). Descriptive statistical methods were used to analyze the distribution of P. aeruginosa by sample sources, MDR patterns by number of isolates and virulence gene carriage by MDR (≥3classes of antibiotics). ResultsA total of forty-seven (47) isolates were confirmed as P. aeruginosa. The isolates showed pan-resistance to cefuroxime and ceftazidime. An elevated level of resistance was also seen in amoxycillin-clavulanic acid, ceftriaxone, cefixime and meropenem. Susceptibility to Amikacin was 95.7 %. Multidrug resistance was seen in forty (85.1 %) of the isolates. P. aeruginosa (100 %) were confirmed with oprL and 74.5 % oprI genes. All isolates (100 %) had lasB, toxA and exoS virulence genes while nan1 was detected in 19.1 % isolates. ConclusionsDiverse and multiple virulence genes were distributed among the multidrug resistant isolates. Understanding the factors contributing to pathogenicity and antibiotic resistance will aid in the treatment of infection. It will also promote judicious use of antimicrobials.

Circulation of Antibiotic-Resistant Escherichia coli in Wild and Domestic Waterfowl in Ukraine.

Background: Antibiotic resistance is becoming an increasingly urgent problem for human and animal health due to the widespread use of antibiotics in medicine, veterinary medicine, and agriculture. At the same time, the natural reservoirs of antibiotic-resistant pathogens remain unclear. Wild birds may play a role in this due to their biology. Escherichia coli is a representative indicator pathogen for antibiotic resistance studies. Materials and Methods: In 2020-2021, sampling of feces and cloacal swabs from six species of wild waterfowl (Eurasian wigeon Anas penelope, Eurasian teal Anas crecca, white-fronted goose Anser albifrons, red-breasted goose Rufibrenta ruficollis, graylag goose Anser anser, shelduck Tadorna tadorna) and from two species of domestic waterfowl (ducks and geese) was conducted in the Kherson, Zaporizhzhia, Odesa, Kharkiv, and Cherkasy regions of Ukraine. Biological material was collected, stored, and transported in cryotubes with transport medium (brain heart infusion broth [BHIB] with the addition of 15% glycerol) in liquid nitrogen. Bacteriological studies were carried out according to standard methods for the isolation and identification of microorganisms. Drug resistance of E. coli was carried out by a standard disk diffusion method. Results: Bacteria representing six families (Enterobacteriaceae, Yersiniaceae, Morganellaceae, Bacillaceae, Pseudomonadaceae, Staphylococcaceae) were isolated from clinically healthy wild birds (wigeon, Eurasian teal, white-fronted goose, red-breasted goose, mallard, graylag goose, shelduck) in the southern regions of Ukraine with isolation rates ranging from 26.7% to 100%. A total of 19 E. coli isolates were cultured from 111 samples from wild birds, and 30 isolates of E. coli were cultured from 32 poultry samples. E. coli was isolated from birds of all species. The prevalence of E. coli ranged from 5.0% to 33.3% in wild waterfowl and from 90.9% to 100% in domestic waterfowl. The prevalence of multidrug-resistant (MDR) E. coli ranged from 10.0% to 31.8% in wild and domestic waterfowl: 3 of 15 (20%) specimens from wild mallard were MDR in the Kherson region, as well as 7 of 22 domestic ducks (31.8%) and 1 of 10 geese (10%) in the Kharkiv and Cherkasy regions. Isolates from wild birds were the most resistant to ampicillin (AMP), amoxiclav (AMC), amoxicillin (AMX), doxycycline (DO), and chloramphenicol (C). Isolates from poultry were resistant to ampicillin, amoxiclav, doxycycline, amoxicillin, chloramphenicol, and enrofloxacin (EX). Most of the other E. coli isolates from wild waterfowl were classified as non-multidrug-resistant (non-MDR) forms. Analysis of antibiotic sensitivity phenotypes showed that only four antibiotic-resistant phenotypes were detected among non-MDR bacteria, whereas among the MDR bacteria, two antibiotic-resistant phenotypes were detected in mallards and six in domestic waterfowl. Conclusion: The results of this study showed that wild waterfowl in Ukraine, which live in natural conditions and do not receive any antimicrobial drugs, are carriers of E. coli that are resistant to a number of antibiotics that are actively used in industrial poultry.

Assessment of cefiderocol disk diffusion versus broth microdilution results when tested against Acinetobacter baumannii complex clinical isolates.

The aim of this study was to evaluate the correlation between inhibitory zones and minimum inhibitory concentrations (MICs) when testing cefiderocol against Acinetobacter baumannii complex using disk diffusion and the broth microdilution (BMD) method according to the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Four-hundred and sixty-eight non-duplicated A. baumannii complex clinical isolates were collected from 56 hospitals of the China Antimicrobial Surveillance Network from 2019 to 2021. BMD using iron-depleted cation-adjusted Mueller-Hinton broth (ID-CAMHB) and standard disk diffusion methods were performed according to CLSI guidelines. Results were interpreted according to the CLSI and EUCAST breakpoints. Categorical agreement (CA), minor error (mE), major error (ME), and very major error (VME) were calculated for disk diffusion methods. The susceptibilities of all A. baumannii complex isolates by BMD were 98.7% (CLSI) and 97.6% (EUCAST). For all A. baumannii complex isolates, CA was 98.1% (CLSI) and 97.0% (EUCAST), with 0.9% (CLSI) and 1.9% (EUCAST) of VME, respectively. For the carbapenem-susceptible A. baumannii complex, the CA was 100%, with no mE or VME using both CLSI and EUCAST breakpoints. For carbapenem-resistant A. baumannii complex, CA was 97.5% (CLSI) and 96.2% (EUCAST), with 1.1% (CLSI) and 2.5% (EUCAST) of VME, respectively. Regarding the difficult-to-treat resistance A. baumannii complex isolates, CA was 97.6% (CLSI) and 95.7% (EUCAST), with 1.2% (CLSI) and 3.1% (EUCAST) of VME, respectively. Cefiderocol disk diffusion was difficult to assess in this study. Very few isolates were resistant to cefiderocol by BMD using CLSI breakpoint, and these were categorized as susceptible with the disk diffusion test. This study did, however, show that the main proportion of A. baumannii isolates were susceptible to cefiderocol by BMD, including carbapenem-resistant A. baumannii. IMPORTANCE Carbapenem-resistant Acinetobacter baumannii is a major global health concern due to its high prevalence and limited treatment options. Cefiderocol is the only novel Food and Drug Administration (FDA)-approved β-lactam agent for the salvage treatment of carbapenem-resistant A. baumannii infection. Currently, a commercial automated susceptibility testing panel of cefiderocol is unavailable. Both the preparation of iron-depleted cation-adjusted Mueller-Hinton broth and the performance of broth microdilution are cumbersome in routine microbiology laboratories. A disk diffusion method is convenient for cefiderocol antimicrobial susceptibility testing, but limited data are available specifically for A. baumannii clinical isolates. Moreover, the Clinical and Laboratory Standards Institute published revisions to the A. baumannii cefiderocol disk diffusion breakpoints in 2022. Hence, we evaluated the performance of cefiderocol disk diffusion compared with the reference BMD against A. baumannii clinical isolates, especially those with cefiderocol zone diameters ≤ 14 mm.

Characterization and Antimicrobial Susceptibility Patterns of Listeria monocytogenes from Raw Cow Milk in the Southern Part of Ethiopia

Food safety remains the main health concern in the developing countries. Thus, the major purpose of the present study was to characterize and determine antibiotic susceptibility patterns of Listeria monocytogenes from raw milk samples collected from southern Ethiopia. Two hundred and forty raw cow milk samples were collected from dairy farms and smallholder dairy producers using a simple random sampling technique and analyzed by cultural and multiplex PCR methods. The antimicrobial susceptibility profile of L. monocytogenes was evaluated using the standard disk diffusion method. Over 28% of the samples were found positive for Listeria spp., of which 17 (7.08%) isolates were identified as L. monocytogenes after morphological and biochemical confirmation. The prevalence of L. monocytogenes was 6.02% in Hawassa city, 5.56% in Dale district, and 9.41% in Arsi Negele district. L. monocytogenes was higher in the wet season (9.32%) than in the dry season (4.92%). The gene for Listeria specific 16S rRNA was detected in all the 17 examined isolates, while hlyA and iapA were only found in 11 of them. Furthermore, no isolate was identified to have the prfA, actA, or plcA genes. Antimicrobial resistance profiling revealed that all the L. monocytogenes isolates were resistant to nalidixic acid (100%), followed by erythromycin (88.24%). However, all the L. monocytogenes isolates were sensitive to vancomycin, gentamicin, and sulfamethoxazole. Raw cow milk is a potential source of L. monocytogenes and it poses a threat to human and animal health. Therefore, it is crucial that dairy producers and vendors of raw milk in the study areas should take considerable precautions to prevent Listeria species from contaminating raw fresh milk.

Anthropic Impact on the Critically Endangered Melanophryniscus admirabilis (Admirable Redbelly Toad): Evidence from the Presence of Multiresistant Enterobacteriaceae.

Melanophryniscus admirabilis is a microendemic and critically endangered toad, known from a single population. This microendemic species inhabits a small fragment of the Atlantic Forest in South Brazil, an area significantly impacted by hydroelectric power plant projects, livestock farming, agricultural activities, biopiracy, and tourism. Given the exclusive and limited population of M. admirabilis, preserving and conserving this species is of utmost importance in Brazil. Research on this species primarily concentrates on its biology, ecology, and ecotoxicology. Currently, there is no knowledge about antimicrobial resistance (AMR) bacteria present in wild M. admirabilis, despite the potential for studying them to provide valuable insights into environmental pollution. To this end, Enterobacteriaceae species (n = 82) obtained from 15 wild M. admirabilis toads were subjected to the standard Kirby-Bauer disk diffusion method to test their AMR. The results showed that Enterobacteriaceae species had the highest antibiotic resistance to IPM (45.1%), CIP (39%), NIT (32.5%), AMP (31.3%), TET (18.3%), and FOX (17%). Of the tested species, 18 (21.9%) species tested were susceptible, 40 (48.8%) were resistant to 1 or 2 different antibiotic classes, and 24 (29.3%) were classified as multidrug-resistant. Overall, our findings suggest that the incidence of AMR in Enterobacteriaceae isolated from wild M. admirabilis is high, indicating environmental stress caused by anthropic pollution in their habit.

Spectrophotometrically, Spectroscopically, Microscopically and Thermogravimetrically Optimized TiO2 and ZnO Nanoparticles and their Bactericidal, Antioxidant and Cytotoxic Potential: A Novel Comparative Approach.

Current study was aimed to determine the antibacterial, antioxidant and cytotoxic potential of Titanium dioxide nanoparticles (TiO2NPs) and Zinc oxide nanoparticles (ZnONPs). Nanoparticles were characterized by UV-Vis spectrophotometry, particle size analyzer (PSA), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy(SEM), and thermogravimetric analysis (TGA). The Minimum inhibitory concentration (MIC) was determined by standard agar dilution method. Antibacterial potential of nanoparticles was analyzed by standard disc diffusion method against bacterial strains including Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. Different concentrations of NPs (0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4mg/mL) were incorporated to evaluate the antimicrobial activity. Antioxidant activity and cytotoxicity of these NPs was analyzed by DPPH method and brine shrimp cytotoxicity assay, respectively. The MIC of TiO2NPs against E. coli, P. aeruginosa and K. pneumoniae was 0.04, 0.08 and 0.07mg/mL respectively while the MIC of ZnONPs against the above strains was 0.01, 0.015 and 0.01mg/mL. The maximum zone of inhibition was observed for K. pneumoniae i.e., 20mm and 25mm against TiO2 and ZnO NPs respectively, at 1.4mg/mL concentration of NPs. The susceptibility of NPs against bacterial strains was evaluated in the following order: K. pneumoniae > P. aeruginosa > E. coli. The antioxidant activity of nanoparticles increased by increasing the concentration of NPs while cytotoxic analysis exhibited non-toxic effect of ZnO NPs while TiO2 had toxic effects on 1.2 and 1.4mg/mL concentrations. Results revealed that ZnO NPs have moreantibacterialand negligiblecytotoxic potential in contrast to TiO2 NPs.

Antibacterial Activity of Transition Metal Mn(II), Co(II), Ni(II) and Cu(II) Complexes Containing Bioactive Ligands

The Present research work describes biological activity of amide group containing ligands and their Mn(II), Ni(II), Co(II) and Cu(II) complexes against E.coli and S.aureus. The standard disc diffusion method has been employed for investigations. The data obtained during study has been correlated for structure activity relationship and a trend has been pointed for a series of complexes.

Carbapenem-resistant Klebsiella pneumoniae outbreak with monoclonal spread: Evaluation of resistance genes and ceftazidime-avibactam susceptibility

PurposeThe aim of this study was to investigate ceftazidime-avibactam (CAZ-AVI) susceptibility, carbapenemase genes, and clonal relationship in carbapenem-resistant Klebsiella pneumoniae (CrKp) isolates. MethodsA total of 28 non-repetitive CrKp isolates with positive carbapenemase production determined by the modified carbapenem inactivation method (mCIM), were included in the study. Identification of the isolates was performed with MALDI-TOF MS (VITEK-MS, bioMerieux, France). The automated system (VITEK-2, bioMerieux) and gradient diffusion test (Etest, bioMerieux) were used to determine antibiotic susceptibility. The mCIM was performed according to CLSI (2021) recommendations. CAZ-AVI susceptibility was carried out using the standard disc diffusion method. Results were evaluated according to EUCAST 2022 criteria. The blaOXA-48, blaNDM, blaKPC, blaIMP and blaVIM genes were investigated by multiplex PCR. The clonal relationship between isolates was determined by both AP-PCR and PFGE methods. ResultsOf the total 28 isolates, 89.3% were susceptible to CAZ-AVI. blaOXA-48 gene was found in 85.7% of the isolates, blaOXA-48+blaNDM gene in 10.7%, and blaNDM gene in 3.6%. blaKPC, blaIMP and blaVIM genes were not detected. Three clusters with three different genotypes were determined by the PFGE method. The largest cluster was Genotype A (n:24), followed by Genotype B (n:3), and Genotype C (n:1). AP-PCR was highly compatible with PFGE. The isolates of Genotype A, mostly from the intensive care unit (ICU), were evaluated as outbreak strains with monoclonal dissemination. ConclusionsOXA-48 remains the most frequently detected enzyme in CrKp strains in our country. The ceftazidime-avibactam susceptibility rate of 89.3% indicates that this antibiotic is still effective against CrKp isolates. The unnoticed outbreak detected in our study revealed the severity of intra-hospital cross-contamination affecting different wards, including the ICU. Therefore, in order to limit the spread of CrKp isolates, it is of great importance to implement strict infection control measures, and molecular surveillance programs, especially in the ICU.

Light tolerance of extended spectrum β-lactamase producing Escherichia coli strains after repetitive exposure to far-UVC and blue LED light.

The aim of this study was to investigate dual far-UVC (Ultraviolet-C) (222nm) and blue LED (Light Emitting Diode) (405nm) light on the inactivation of extended spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) and to determine if repetitive exposure to long pulses of light resulted in changes to light tolerance, and antibiotic susceptibility. Antimicrobial efficiency of dual and individual light wavelengths and development of light tolerance in E. coli was evaluated through a spread plate method after exposure to light at 25cm. Dual light exposure for 30min resulted in a 5-6 log10 CFU mL-1 reduction in two ESBL-Ec and two antibiotic-sensitive control E. coli strains. The overall inhibition achieved by dual light treatment was always greater than the combined reductions (log10 CFU) observed from exposure to individual light wavelengths (combined 222-405nm), indicating a synergistic relationship between blue LED and far-UVC light when used together. Repetitive long pulses of dual and individual far-UVC light exposure resulted in light tolerance in two ESBL-Ec strains but not the antibiotic-sensitive E. coli strains. Subsequent passages of repetitive light-treated ESBL-Ec strains continued to exhibit light tolerance. Antibiotic susceptibility was determined through a standard disk diffusion method. No changes were observed in the antibiotic susceptibility profiles for any of the four strains after exposure to either dual or individual wavelengths. Dual light exposure was effective in the disinfection of ESBL-Ec in solution; however, antibiotic-resistant E. coli were able to develop light tolerance after repetitive exposure to light.

Assessment of ear infection in children attending Dalhatu Araf specialist Hospital, Lafia

Bacterial infection of the ear, especially amongst children from low-income countries, is a major cause of hospitalization, presenting in different forms and severity. The prevalence and antibiotic profile of bacteria associated with ear infection amongst children between the ages 0–10years presenting with symptoms was determined using standard microbiological procedures and Kirby-Bauer disk diffusion methods. The results showed an 89.6% prevalence rate of bacterial ear infections, with males and children aged 0–1 years accounting for 53.7% and 28.9% of cases respectively. Pseudomonas spp. was the most prevalent (32.6%) bacteria isolated, while Klebsiella spp. was the least prevalent (8.9%). Male children had higher distribution and presence of bacterial growths than their female counterparts. Antimicrobial assay revealed high susceptibility rates as well as multidrug resistance of the bacterial isolates to the antibiotics tested. Cefuroxime and Augmentin were most effective against all isolates. This study showed a high prevalence of bacterial-associated ear infections dominated by Pseudomonas spp. and more prevalent in males and children between 0 and 3 years old. This calls for improved postnatal care education and child hygiene by nursing mothers, midwives and nannies to forestall and prevent any public health challenge that might arise from the uncontrolled spread and increase in pathogenicity of infections caused by the isolates.

Prevalence of MLSB Phenotypes of &lt;i&gt;Staphylococcus aureus&lt;/i&gt; isolates in a tertiary care hospital of Delhi

Against the backdrop of the ever-changing Staphylococcal resistance pattern, clindamycin remains a viable therapeutic alternative Variation of Clindamycin drug resistance patterns with geographic area make inducible clindamycin resistance testing imperative for all staphylococcal isolates to avoid therapeutic failure. This was a prospective study conducted over a period of 1.5 years from January 2021 until June 2022. Prevalence of different MLSB Phenotypes of Staphylococcus aureus isolates was determined by standard disc diffusion method as per CLSI guidelines. Pyogenic samples received in the Microbiology lab that yielded Staphylococcus aureus were further tested for the presence of clindamycin resistance by disc diffusion method. Out of 6586 total pyogenic and respiratory specimens received in the lab, Staphylococcus aureus was yielded in 752 samples. On further testing for the MLSB phenotypes, 16.3% isolates were found to be iMLSB, 19.28% were cMLSB, 43.1% were of MSB type. ICR screening will reduce the unessential subjection of the patient to the antibiotic, and would prevent unnecessary adverse effects in the patients.

Identification of serotypes of Mannheimia haemolytica and Pasteurella multocida from pneumonic cases of sheep and goats and their antimicrobial sensitivity profiles in Borana and Arsi zones, Ethiopia

Respiratory diseases caused by Mannheimia haemolytica (M. haemolytica) and Pasteurella multocida (P. multocida) have been known to result in a considerable loss due to mortality and reduced production. This study aimed at isolation and identification of M. haemolytica and P. multocida associated with pneumonic pasteurellosis in sheep and goats using bacteriological and molecular techniques. Identification of serotypes of M. haemolytica and P. multocida was done using indirect haemagglutination test. The in vitro antimicrobial sensitivity profiles of the M. haemolytica were tested using standard disk diffusion method. A total of 52 and 78 nasal swabs were collected from pneumonic cases for bacterial isolation and identification in Borana and Arsi zone, respectively. Four hundred sera samples were collected for identification of serotypes. The results showed that 17 of 52 (32.69%; 95% CI 20.33, 47.11) nasal swabs collected from pneumonic animals in Borana yielded positive results for Pasteurella/Mannheimia species, 13 (25.00%; 95% CI 14.03, 38.95) of which were M. haemolytica. None of the samples yielded P. multocida. Twenty-three of 78 (29.49%; 95% CI 19.69, 40.89) nasal swabs collected at Arsi from pneumonic animals yielded positive results for M. haemolytica (17) and P. multocida (6). Secondary biochemical characterization revealed that 14 of the 17 isolates conform to M. haemolytica whereas none of the 6 isolates suspected to be P. mutocida were confirmed. Eleven (84.62%) isolates from Borana and 4 (28.57%) from Arsi were confirmed to be M. haemolytica using PCR targeting the Rpt2 genes. Assay for M. haemolytica serotype A1 revealed all belong to A1. None of the isolates with cultural and morphological features of P. multocida gave positive results by molecular assay. Serological assay identified three serotypes of M. haemolytica namely A1, A2 and A7 almost in all of the samples whereas P. multocida serotype A was detected in 78.75% of the samples. The M. haemolytica isolates tested for susceptibility to antibiotics showed resistance against Bacitracin (83.33%) and Penicillin (50.00%) while they were found susceptible to Gentamycin (100%), Chloramphenicol (100%) and Sulfamethoxazole (100%) and Tetracycline (83.33%). In conclusion, the results of the present study revealed the association of M. haemolytica with pneumonic pasteurellosis in sheep and goats and can be of use in vaccine development in Ethiopia. Nevertheless, further investigations and continuous monitoring of antimicrobial resistance and appropriate selection and prudent use of antimicrobials in livestock sector are required.

Prevalence, Pathogenic Bacterial Profile and Antimicrobial Susceptibility Pattern of Urinary Tract Infection Among Children with Congenital Anomalies of the Kidney and Urinary Tract.

The study was to detect the pathogenic bacterial profile and antibiogram among children with congenital anomalies of the kidney and urinary tract (CAKUT). A retrospective analysis was performed using medical records of urine culture results and antibiotic susceptibility results in patients with UTIs from March 2017 to March 2022. Antimicrobial susceptibility pattern was determined by a standard agar disc diffusion method. A total of 568 children were included. The proportion of culture-positive UTI was 59.15% (336/568). More than nine types of bacteria were isolated with most pathogens being Gram-negative species. Among Gram-negative isolates, the predominant bacteria were Escherichia coli (30.95%, 104/336) followed by Klebsiella pneumoniae (9.23%). Escherichia coli isolates were highly sensitive to amikacin (95.19%), ertapenem (94.23%), nitrofurantoin (93.27%), imipenem (91.35%), and piperacillin-tazobactam (90.38%) and high rate of resistant were also detected to ampicillin (92.31%), cephazolin (73.08%), ceftriaxone (70.19%), trimethoprim-sulfamethoxazole (61.54%) and ampicillin-sulbactam (57.69%). Klebsiella pneumoniae isolates showed sensitive to ertapenem (96.77%), amikacin (96.77%), imipenem (93.55%), piperacillin-tazobactam (90.32%) and gentamicin (83.87%), while highly resistant were observed to ampicillin (96.77%), cephazolin (74.19%), ceftazidime (61.29%), ceftriaxone (61.29%), and aztreonam (61.29%). The isolated Gram-positive bacteria mainly contained Enterococcus faecalis and Enterococcus faecium (each 15.77%). Enterococcus faecalis were sensitive to vancomycin, penicillin-G, tigecycline, nitrofurantoin and linezolid (100%, 94.34%, 88.68%, 88.68%, 86.79, respectively) and resistant to tetracycline (86.79%), quinupristi (83.02%), erythromycin (73.58%). Enterococcus faecium also showed a similar result. Multiple drug resistance (MDR) was observed in 264 (80.00%) of the 360 bacterial isolates. Only age was significantly associated with a culture-positive UTI. A higher prevalence of culture-positive UTI was detected. Escherichia coli was the most prevalent uropathogen followed by Enterococcus faecalis and Enterococcus faecium. These uropathogens showed highly resistant to the commonly used antibiotics. Moreover, MDR was commonly observed. Thus, empiric therapy is unsatisfactory as drug sensitivity always varies over time.

Detection of multidrug-resistant Shiga toxin-producing Escherichia coli in some food products and cattle faeces in Al-Sharkia, Egypt: one health menace

BackgroundShiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen, that is transmitted from a variety of animals, especially cattle to humans via contaminated food, water, feaces or contact with infected environment or animals. The ability of STEC strains to cause gastrointestinal complications in human is due to the production of Shiga toxins (sxt). However, the transmission of multidrug-resistance STEC strains are linked with a severity of disease outcomes and horizontal spread of resistance genes in other pathogens. The result of this has emerged as a significant threat to public health, animal health, food safety, and the environment. Therefore, the purpose of this study is to investigate the antibiogram profile of enteric E. coli O157 isolated from food products and cattle faeces samples in Zagazig City, Al-Sharkia, Egypt, and to reveal the presence of Shiga toxin genes stx1 and stx2 as virulence factors in multidrug-resistant isolates. In addition to this, the partial 16S rRNA sequencing was used for the identification and genetic recoding of the obtained STEC isolates.ResultsThere was a total of sixty-five samples collected from different geographical regions at Zagazig City, Al-Sharkia—Egypt, which were divided into: 15 chicken meat (C), 10 luncheon (L), 10 hamburgers (H), and 30 cattle faeces (CF). From the sixty-five samples, only 10 samples (one from H, and 9 from CF) were identified as suspicious E. coli O157 with colourless colonies on sorbitol MacConkey agar media with Cefixime- Telurite supplement at the last step of most probable number (MPN) technique. Eight isolates (all from CF) were identified as multidrug-resistant (MDR) as they showed resistance to three antibiotics with multiple antibiotic resistance (MAR) index ≥ 0.23, which were assessed by standard Kirby-Bauer disc diffusion method. These eight isolates demonstrated complete resistance (100%) against amoxicillin/clavulanic acid, and high frequencies of resistance (90%, 70%, 60%,60%, and 40%) against cefoxitin, polymixin, erythromycin, ceftazidime, and piperacillin, respectively. Those eight MDR E. coli O157 underwent serological assay to confirm their serotype. Only two isolates (CF8, and CF13), both from CF, were showed strong agglutination with antisera O157 and H7, as well as resistance against 8 out of 13 of the used antibiotics with the highest MAR index (0.62). The presence of virulence genes Shiga toxins (stx1 and stx2) was assessed by PCR technique. CF8 was confirmed for carrying stx2, while CF13 was carrying both genes stx1, and stx2. Both isolates were identified by partial molecular 16S rRNA sequencing and have an accession number (Acc. No.) of LC666912, and LC666913 on gene bank. Phylogenetic analysis showed that CF8, and CF13 were highly homologous (98%) to E. coli H7 strain, and (100%) to E. coli DH7, respectively.ConclusionThe results of this study provides evidence for the occurrence of E. coli O157:H7 that carries Shiga toxins stx1 and/or stx2, with a high frequency of resistance to antibiotics commonly used in human and veterinary medicine, in Zagazig City, Al-Sharkia, Egypt. This has a high extent of public health risk posed by animal reservoirs and food products with respect to easy transmission causing outbreaks and transfer resistance genes to other pathogens in animal, human, and plants. Therefore, environmental, animal husbandry, and food product surveillance, as well as, clinical infection control, must be strengthened to avoid the extra spread of MDR pathogens, especially MDR STEC strains.

Isolation of Carbapenem and Colistin Resistant Gram-Negative Bacteria Colonizing Immunocompromised SARS-CoV-2 Patients Admitted to Some Libyan Hospitals.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a devastating effect, globally. We describe, for the first time, the occurrence of carbapenem-resistant bacteria colonizing SARS-CoV-2 patients who developed hospital-associated infections with carbapenemase-producing, Gram-negative bacteria at some isolation centers of SARS-CoV-2 in the eastern part of Libya. In total, at first, 109 samples were collected from 43 patients, with the samples being recovered from oral (n = 35), nasal (n = 45), and rectal (n = 29) cavities. Strain identification was performed via matrix assisted laser desorption ionization-time of flight (MALDI-TOF). Antibiotic susceptibility testing was carried out on Mueller-Hinton agar, using the standard disk diffusion method. MIC determination was confirmed via E-TEST and microdilution standard methods. A molecular study was carried out to characterize the carbapenem and colistin resistance in Gram-negative bacterial strains. All of the positive results were confirmed via sequencing. Klebsiella pneumoniae (n = 32), Citrobacter freundii (n = 21), Escherichia coli (n = 7), and Acinetobacter baumannii (n = 21) were the predominant isolated bacteria. Gram-negative isolates were multidrug-resistant and carried different carbapenem resistance-associated genes, including NDM-1 (56/119; 47.05%), OXA-48 (15/119; 12.60%), OXA-23 (19/119; 15.96%), VIM (10/119; 8.40%), and the colistin resistance mobile gene mcr-1 (4/119; 3.36%). The overuse of antimicrobials, particularly carbapenem antibiotics, during the SARS-CoV-2 pandemic has led to the emergence of multidrug-resistant bacteria, mainly K. pneumoniae, A. baumannii, and colistin-resistant E. coli strains. Increased surveillance as well as the rational use of carbapenem antibiotics and, recently, colistin are required to reduce the propagation of multidrug-resistant strains and to optimally maintain the efficacy of these antibiotics. IMPORTANCE In this work, we describe, for the first time, the occurrence of carbapenem-resistant bacteria colonizing COVID-19 patients who developed hospital-associated infections with carbapenemase-producing, Gram-negative bacteria at some isolation centers of COVID-19 in the eastern part of Libya. Our results confirmed that the overuse of antimicrobials, such as carbapenem antibiotics, during the COVID-19 pandemic has led to the emergence of multidrug-resistant bacteria, mainly K. pneumoniae and A. baumannii, as well as colistin resistance.

Prevalence, Genetic Homogeneity, and Antibiotic Resistance of Pathogenic Yersinia enterocolitica Strains Isolated from Slaughtered Pigs in Bulgaria.

Yersiniosis is the third most commonly reported foodborne zoonosis in the European Union. Here, we evaluated the prevalence of pathogenic Yersinia enterocolitica among healthy pigs (as a major reservoir) in a slaughterhouse in Bulgaria. A total of 790 tonsils and feces from 601 pigs were examined. Isolation and pathogenicity characterization was carried out by the ISO 10273:2003 protocol and Polymerase Chain Reaction (PCR), detecting the 16S rRNA gene, attachment and invasion locus (ail), Yersinia heat-stable enterotoxin (ystA), and Yersinia adhesion (yadA) genes. Genetic diversity was assessed by pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance by the standard disk diffusion method. Of all the pigs tested, 6.7% were positive for Y. enterocolitica. All isolates belonged to Y. enterocolitica bioserotype 4/O:3. ail, and ystA genes were detected in all positive strains (n = 43), while the plasmid Yersinia virulence plasmid (pYV) was detected in 41. High homogeneity was observed among the strains, with all strains susceptible to ceftriaxone, amikacin and ciprofloxacin, and resistant to ampicillin. In conclusion, a low prevalence of Y. enterocolitica 4/O:3 was found in healthy pigs slaughtered in Bulgaria, not underestimating possible contamination of pork as a potential risk to consumer health.