Setting epidemiological cut-off values relevant to MIC and disc diffusion data for Aeromonas salmonicida generated by a standard method.

The Clinical and Laboratory Standards Institute has published epidemiological cut-off values for susceptibility data generated at 22°°C and read after 44-48 h for florfenicol, oxolinic acid and oxytetracycline against Aeromonas salmonicida. The cut-off values for the minimum inhibitory concentration (MIC) and disc diffusion were derived from data obtained by 1 laboratory and 2 laboratories respectively. The present work reports the generation of susceptibility data from additional laboratories and the calculation of provisional cut-off values from aggregations of these data with previously published data. With respect to MIC data, the provisional cut-off values, derived from aggregations of the data from 4 laboratories, were ≤4 µg ml-1 for florfenicol, ≤0.0625 µg ml-1 for oxolinic acid and ≤1 µg ml-1 for oxytetracycline. For disc diffusion data, the provisional cut-off values derived from aggregations of the data from 5 laboratories were ≥30 mm for florfenicol, ≥32 mm for oxolinic acid and ≥25 mm for oxytetracycline. In addition, a cut-off value of ≥29 mm for ampicillin was derived from the aggregation of data from 4 laboratories.

Magnitude and antimicrobial susceptibility profile of bacteria isolated from pediatric sepsis cases at University of Gondar Hospital, Northwest Ethiopia.

BACKGROUND: Sepsis is one of the major causes of morbidity and mortality among pediatric patients throughout the world. The varying microbiological pattern of sepsis warrants the need for researches on the causative organisms and their antimicrobial susceptibility pattern. The epidemiology of neonatal and pediatric sepsis in Ethiopia is under-research. The objective of this study was to evaluate the burden of bacterial pathogens and their antimicrobial susceptibility patterns among children suspected of sepsis. METHODS: An institutional-based prospective cross-sectional study was conducted on 370 pediatric(age birth-15 years) patients suspected of sepsis at the University of Gondar Comprehensive Specialized hospital from December 2020 to November 2021. Blood samples were collected aseptically and inoculated into Tryptone Soya Broth for culture. The organisms grown were identified by standard microbiological methods and subjected to antibiotic susceptibility testing by modified Kirby-Bauer disk diffusion method recommended by Clinical laboratory and standard institute. Methicillin resistance was confirmed using Cefoxitin disk diffusion method. Data entry and analysis were done using Statistical Package for Social Sciences (SPSS) version 26 software. A p-value less than 0.05 at 95% confidence interval was considered statically significant. RESULTS: Out of the total 370 study subjects, 21.6% (80/370) of them were culture positive. Of these, 43 (53.8%) and 37 (46.3%) were Gram-positive and Gram-negative bacterial pathogens, respectively. The most prevalent Gram-positive bacterial isolate was Staphylococcus aureus (n = 24; 30%) and coagulase negative staphylococci (n = 7; 8.8%). Among the Gram-negative bacterial isolates, the leading bacteria was Klebsiella pneumoniae (n = 20; 25%) followed by Escherichia coli (n = 7; 8.8%). Clindamycin, Chloramphenicol, Gentamicin and Ciprofloxacin were the most effective antibiotics against Gram-positive bacterial isolates while Amikacin, Meropenem and Chloramphenicol were effective against Gram-negative pathogens. Methicillin resistance was detected in 45.8% of Staphylococcus aureus. Multi-drug resistance (MDR) antimicrobial susceptibility pattern was observed in 76% of the bacterial isolates. CONCLUSION: Gram positive bacteria were the predominant isolates among pediatric sepsis cases and most of the bacterial isolates showed MDR. Staphylococcus aureus and Klebsiella pneumoniae were frequently isolated bacteria. The high prevalence of drug resistance warrants rational use of antibiotics and the need for regular antibiotic susceptibility surveillance studies.

Association between respiratory disease pathogens in calves near feedlot arrival with treatment for bovine respiratory disease and subsequent antimicrobial resistance status.

Introduction: This study assessed the risk of first treatment for bovine respiratory disease (BRD) given detection of nasopharyngeal bacteria (Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni) and corresponding likelihood of antimicrobial susceptibility (C/S) at two time points during the early feeding period. Relationships between C/S results and later treatment for BRD were evaluated at both the calf-level and pen-level. The association between calf-level and pen-level C/S findings during the early feeding period and subsequent C/S results at BRD treatment were also reported. Methods: Auction-sourced, recently-weaned beef calves (n = 1,599 steers) were placed in adjacent feedlot pens (8 × 100 calves) in two subsequent years. Deep nasopharyngeal (DNP) swabs were collected from all calves at time of arrival processing (1DOF) and before metaphylaxis administration with either tulathromycin or oxytetracycline, 12 days later (13DOF), and at the time of first treatment for BRD. All samples were tested for C/S. Results: Several pen-level and individual calf-level C/S measures of interest were associated with future treatment for BRD and C/S at the time of treatment. The median DOF for first BRD treatment was 24 days following tulathromycin metaphylaxis and 11 days following oxytetracycline. Overall, sampling at 13DOF resulted in the best fit for more models of subsequent treatment for BRD and C/S results at BRD treatment than for sampling at arrival. In individual calves, recovery of M. haemolytica, P. multocida, or H. somni at 13DOF was associated with subsequent treatment for BRD within 45DOF. Pen-level prevalence of Pasteurellacea bacteria with tetracycline or macrolide resistance at arrival and 13DOF were associated with detection of bacteria with antimicrobial resistance (AMR) at BRD treatment, as were individual calf results at 13DOF. Discussion: These findings suggest that the bacteria and AMR outcomes recovered from cattle near two weeks on feed can inform the prediction of future BRD risk and concurrent antimicrobial susceptibility results at time of first BRD treatment. Notably, the associations between pen-level C/S results from previous testing and corresponding findings in calves with BRD from the same pen suggested potential testing strategies to inform antimicrobial use protocols for feedlot cattle.

Biofilm Dairy Foods Review: Effect of biofilm production on antimicrobial susceptibility of Staphylococcus aureus bovine mastitis strains from the most prevalent Canadian spa types.

Staphylococcus aureus intramammary infections often leads to clinical and subclinical mastitis in dairy cattle. Prediction of disease evolution and treatment efficacy based on the characteristics of disease-causing strains of S. aureus would significantly improve management of dairy herds. To study the impact of biofilm production and the influence of genetic lineage, we selected S. aureus isolates from the most prevalent Canadian spa types associated with bovine mastitis. Antimicrobial susceptibility in planktonic growth and for bacteria embedded in biofilm was compared. PCR was used to detect the bap gene responsible for atypical biofilm formation. All Canadian spa types from dairy cattle were susceptible to the 8 antimicrobial agents tested. Only strain sa3493 from spa type t267 showed a resistance to pirlimycin. However, bacteria producing larger amounts of biofilms better survived the bactericidal action of antimicrobial agents even when exposed to concentrations 64 folds higher than the minimal inhibitory concentration determined for planktonic cultures. Pirlimycin was more effective on bacteria producing low to moderate levels of biofilm compared with vancomycin or ceftiofur. Antimicrobial agents did not affect the viability of spa types t13401 and t605 that were high biofilm producers. While both these spa types produced high amounts of biofilm, only t605 possessed the bap gene. We also found a close relationship between DIM at sampling and the presence of spa type t605 isolates. These results suggest that detection of S. aureus spa type may help predict the effectiveness of antimicrobial therapy and that some spa types are more likely to be retrieved toward the end of the lactation.

Multicenter surveillance of the outcomes of and antimicrobial susceptibility to acute cystitis caused by Staphylococcussaprophyticus.

In this study, we aimed to investigate the antimicrobial susceptibility of Staphylococcus saprophyticus in Japan. Additionally, we evaluated the effectiveness of different therapeutic agents and compared the differences in their outcomes in treating S. saprophyticus-induced acute cystitis, considering that cephem antibiotics are standard treatments for acute cystitis in Japan. This retrospective study was conducted at ten hospitals housing urology departments, where urologists were dispatched from the Department of Nephro-Urology, Nagoya City University Graduate School of Medicine. Initially, we prepared a list of S. saprophyticus cases detected between January 2012 and December 2021, using the bacteriological testing system of each hospital. Subsequently, we reviewed the electronic medical records of the listed cases to investigate the causative diseases, treatments, and outcomes in patients with acute cystitis. The number of S. saprophyticus samples collected in this study was 289 from urine specimens, including 157 from women with acute cystitis. All antimicrobial agents demonstrated good therapeutic efficacy in all patients, except in those who did not return for follow-up visits (30 %). Furthermore, only one case of inadequate therapeutic efficacy was observed in a patient treated with a third-generation cephalosporin. All the other patients were cured. These findings revealed that the susceptibility of S. saprophyticus to different antimicrobials did not differ considerably between the specimens from patients with acute cystitis and those from other patients, suggesting a similar trend of therapeutic efficacies of the tested antimicrobials against S. saprophyticus-induced acute cystitis.

Evaluation of Gradient Diffusion in vitro Susceptibility Testing of Aerococcus urinae.

OBJECTIVES: Aerococcus urinae antimicrobial susceptibility testing (AST) can be performed via broth microdilution (BMD) with Mueller-Hinton broth supplemented with lysed horse blood (MHB-LHB). We sought to compare this to the commonly used gradient diffusion method. METHODS: We compared BMD with MHB-LHB to gradient diffusion via MH agar supplemented with sheep blood for 190 A. urinae isolates against sixteen antimicrobials. RESULTS: No antimicrobials demonstrated over 90% essential and categorical agreement (EA and CA) and less than 3% major and very major error rates (ME and VME). Trimethoprim-sulfamethoxazole (TMP-STX) demonstrated an 81% major error rate and ceftriaxone demonstrated a 76% very major error rate. Agar dilution (AD) with lysed horse blood was performed for TMP-STX against 94 isolates and found 100% susceptibility, consistent with previous studies. CONCLUSIONS: Our findings cannot support the routine use of gradient diffusion with MH agar supplemented with sheep blood for A. urinae in lieu of the CLSI method given its limitations in detecting resistant strains. Our results suggest A. urinae is usually susceptible to penicillin, linezolid, tetracycline, and vancomycin. Future studies should evaluate alternative testing methods for clinical microbiology laboratories.

A Case of Sepsis in Which Escherichia coli and Fastidiosipila sanguinis Were Isolated and Identified From a Blood Culture.

We isolated Fastidiosipila sanguinis for the first time in Asia, alongside Escherichia coli, from blood culture specimens in a case of complicated urinary tract infection with sepsis. In our case, F. sanguinis took 96 hours to form colonies under anaerobic culture and showed sensitivity to ceftriaxone, administered for the urinary tract infection. The pathogenicity and clinical significance of F. sanguinis, as well as its impact on the host when coinfected with other pathogens, require further analysis through the accumulation of cases.

Antimicrobial susceptibility and virulence gene analysis of Shigella species causing dysentery in Iranian children: Implications for fluroquinolone resistance.

Shigella species significantly impact global health due to their role in diarrheal diseases. A 2019-2022 cross-sectional study on 432 stool samples from pediatric patients in Mashhad, Iran, identified Shigella spp. and tested their susceptibility to 12 antimicrobials by the disk diffusion method. The presence of virulence factors, namely ipaH, virA, stx1, and stx2, as well as plasmid-mediated quinolone resistance (PMQR) genes, including qnrA, qnrB, qnrC, qnrD, and qnrS, were ascertained through the utilization of polymerase chain reaction techniques. Sequencing of 15 isolates detected mutations within quinolone resistance-determining regions (QRDRs) at the gyrA and parC genes, indicating fluoroquinolone (FQ) resistance. 19.2 % (83/432) of stool samples contained Shigella, primarily S. sonnei (77.1 %), followed by S. flexneri (21.6 %) and S. boydii (1.2 %). Most isolates were from children under five (55.4 %). All strains had the ipaH gene, lacked stx1 and stx2, and 86.7 % had virA. High resistance was noted for ampicillin and tetracycline (84.3 % each), trimethoprim-sulfamethoxazole (81.9 %), and azithromycin (60.2 %). 87.1 % of isolates were multidrug-resistant (MDR). The most common PMQR genes were qnrA and qnrS (41 % each). The qnrD gene, prevalent in 36.1 % of cases, is reported in Iran for the first time. The most common PMQR profile was qnrADS (15.7 %). Resistance to nalidixic acid and ciprofloxacin was 45.8 % and 12 %, respectively. The Shigella isolates exhibited mutations in the gyrA (at codons 83, 87, and 211) and parC (at codons 80, 84, 93, 126, 128, 129, and 132) genes. The D87Y mutation in the gyrA gene was the most common in Shigella isolates, occurring in 73 % of cases. The F93S and L132T mutations in the parC gene were unique to this study. Empirical FQ therapy in patients infected with MDR Shigella, possessing PMQR determinants and/or mutations in the QRDRs of gyrA and parC, may escalate the risks of secondary diseases, extended treatment duration, therapeutic failure, and resistance spread. Consequently, the necessity for continuous surveillance and genetic testing to detect FQ-resistant Shigella strains is of paramount importance.

Streptococcus equi subspecies equi from strangles suspected equines: molecular detection, antibiogram profiles and risk factors.

Strangles, caused by Streptococcus equi subspecies equi, is a highly infectious disease of equines causing major health issues and financial losses. The aim of the study was to detect the presence of the SeM gene in Streptococcus equi isolated from equine suspected of having strangles. A cross-sectional study design was conducted from July to December 2022 in five districts of the central Gondar zone, Ethiopia. One-hundred sixty swab samples were taken from animals that had been clinically suspected. The SeM gene was detected using polymerase chain reaction, and the antimicrobial susceptibility test was performed using the Kirby-Bauer disc diffusion method. The binary logistic regression model was employed to test for statistical significance. In 31.87% (51/160) of the samples, Streptococcus equi species were isolated, and 31.37% (16/51) of these species carried the SeM gene. There was a significant amount of tetracycline (81.5%), erythromycin (81.5%), and vancomycin (75.5%) resistance among the 16 isolates. Strangles were more likely to be present in animals who shared feed containers (AOR = 7.59; 95% CI = 1.44-39.93), drank from the same water troughs (AOR = 7.74; 95% CI = 1.44-41.01), and spent the night together (AOR = 5.97; 95% CI 1.41-25.37). The findings of this study showed that the research areas harboured Streptococcus equi subspecies equi. Sharing feed containers and water troughs were potential sources of strangles infection; thus, these containers need to be cleaned regularly.

Rapid detection of antimicrobial susceptibility of the Bacteroides fragilis group by flow cytometry: A preliminary study.

A total of nine Bacteroides fragilis group strains and B. fragilis ATCC 25285 were studied. Six antibiotics were used in the study. Broth dilution method was used for flow cytometry (FCM) analysis. Cell suspensions with antibiotics and antibiotic-free were stained with thiazole orange and propidium iodide (PI) to differentiate dead/live cells. The percentage of dead and live cells was calculated using FCM device. Cut-off values for antibiotics (26,7 %, 35,5 % and 30,2 % for meropenem, AMC and clindamycin, respectively) were calculated for dead/live cell differentiation. A common cut-off value was calculated for bactericidal and bacteriostatic (31,8 % and 25,7 % respectively). The PI staining ratios of the B. fragilis ATCC 25285 calculated in the MIC ranges for each antibiotic were under the cut-off values calculated with clinical isolates. The cut-off values we calculated are compatible with MBC rather than MIC values. The FCM method is one of the candidate methods for antimicrobial susceptibility testing.

Hetero-antagonism of avibactam and sulbactam with cefiderocol in carbapenem-resistant Acinetobacter spp.

Cefiderocol, a siderophore-cephalosporine conjugate antibiotic, shows promise as a therapeutic option for carbapenem-resistant (CR) Acinetobacter infections. While resistance has already been reported in A. baumannii, combination therapies with avibactam or sulbactam reduce MICs of cefiderocol, extending its efficacy. However, careful consideration is necessary when using these combinations. In our experiments, exposure of A. baumannii and A. lwoffii to cefiderocol and sulbactam or avibactam led to the selection of cefiderocol-resistant strains. Three of those were subjected to whole genome sequencing and transcriptomic analysis. The strains all possessed synonymous and non-synonymous substitutions and short deletions. The most significant mutations affected efflux pumps, transcriptional regulators, and iron homeostasis genes. Transcriptomics showed significant alterations in expression levels of outer membrane proteins, iron homeostasis, and ß-lactamases, suggesting adaptive responses to selective pressure. This study underscores the importance of carefully assessing drug synergies, as they may inadvertently foster the selection of resistant variants and complicate the management of CR Acinetobacter infections.IMPORTANCEThe emergence of carbapenem-resistant Acinetobacter strains as a serious global health threat underscores the urgent need for effective treatment options. Although few drugs show promise against CR Acinetobacter infections, resistance to both drugs has been reported. In this study, the molecular characterization of spontaneous cefiderocol-resistant variants, a CR A. baumannii strain with antagonism to sulbactam, and an A. lwoffii strain with antagonism to avibactam, provides valuable insights into the mechanisms of resistance to cefiderocol. Some mechanisms observed are associated with mutations affecting efflux pumps, regulators, and iron homeostasis genes. These findings highlight the importance of understanding resistance mechanisms to optimize treatment options. They also emphasize the importance of early evaluation of drug synergies to address the challenges of antimicrobial resistance in Acinetobacter infections.

Bacterial pathogens and antimicrobial susceptibility in ocular infections: A study at Boru-Meda General Hospital, Dessie, Ethiopia.

INTRODUCTION: The eye consists of both internal and external compartments. Several variables, including microbes, dust, and high temperatures can cause eye illnesses that can result in blindness. Bacterial eye infections continue to be a major cause of ocular morbidity and blindness, and their prevalence is periodically rising. The objective of the study was to detect bacterial pathogens and assess their susceptibility profiles to antibiotics in the ophthalmology unit of Boru-meda Hospital in Dessie, Ethiopia. METHODS: A hospital-based cross-sectional study was conducted from February 1 to April 30, 2021, among 319 study participants with symptomatic ocular or peri-ocular infections who were enrolled using a consecutive sampling technique. After proper specimen collection, the specimen was immediately inoculated with chocolate, blood, and MacConkey agar. After pure colonies were obtained, they were identified using standard microbiological methods. The Kirby Bauer disk diffusion method was used to test antimicrobial susceptibility patterns, based on the guidelines of the Clinical and Laboratory Standards Institute. RESULTS: The majority of participants developed conjunctivitis 126 (39.5%), followed by blepharitis 47 (14.73%), and dacryocystitis 45 (14.1%). Overall, 164 (51.4%) participants were culture positive, six (1.9%) participants had mixed bacterial isolates, giving a total of 170 bacterial isolates with an isolation rate of 53.3%. The predominant species was CoNS 47 (27.6%), followed by S. aureus 38 (22.4%) and Moraxella species 32 (18.8%). The overall Multi-Drug Resistance (MDR) rate was 62.9%, with 33 (44.6%) being gram-negative and 74 (77.1%) being gram-positive isolates. CONCLUSION: Conjunctivitis was the dominant clinical case and CoNS, was the predominant isolate. A higher rate of MDR isolates, particularly gram-positive ones, was observed. Efficient peri-ocular or ocular bacterial infection surveillance, including microbiological laboratory data, is necessary for monitoring disease trends.

Antimicrobial resistance of Clostridioides difficile in veterinary medicine around the world: A scoping review of minimum inhibitory concentrations.

Objective: To provide a comprehensive characterization of Clostridioides difficile antimicrobial resistance (AMR) data in veterinary medicine based on the minimum inhibitory concentrations (MICs) of all antimicrobial agents tested in relation to the techniques used. Methods: A systematic scoping review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews (PRISMA-ScR) and its associated checklist. The objective was to provide a synthesis of the evidence in a summarized and analyzed format.To this end, three scientific databases were consulted: Scopus, PubMed, and Web of Science, up until December 2021. Subsequently, all identified literature was subjected to screening and classification in accordance with the established study criteria, with the objective of subsequent evaluation. Study selection and data extraction: A comprehensive analysis was conducted on studies regarding Clostridioides difficile antimicrobial resistance (AMR) in veterinary medicine across various animal species and related sources. The analysis included studies that presented data on antimicrobial susceptibility testing using the E-test, agar dilution, or broth microdilution techniques. The extracted data included minimum inhibitory concentration (MIC) values and a comprehensive characterization analysis. Results: A total of 1582 studies were identified in scientific databases, of which only 80 were subjected to analysis. The research on Clostridioides difficile antimicrobial resistance (AMR) in veterinary medicine is most prolific in Europe and North America. The majority of isolates originate from production animals (55%) and pets (15%), with pigs, horses, and cattle being the most commonly studied species. The tested agents' minimum inhibitory concentrations (MICs) and resulting putative antimicrobial resistance profiles exhibited considerable diversity across animal species and sources of isolation. Additionally, AMR characterization has been conducted at the gene and genomic level in animal strains. The E-test was the most frequently utilized method for antimicrobial susceptibility testing (AST). Furthermore, the breakpoints for interpreting the MICs were found to be highly heterogeneous and frequently observed regardless of the geographical origin of the publication. Conclusions: Antimicrobial susceptibility testing techniques and results were found to be diverse and heterogeneous. There is no evidence of an exclusive antimicrobial resistance pattern in any animal species. Despite the phenotypic and genomic data collected over the years, further interdisciplinary studies are necessary. Our findings underscore the necessity for international collaboration to establish uniform standards for C. difficile antimicrobial susceptibility testing (AST) methods and reporting. Such collaboration would facilitate a "One Health" approach to surveillance and control, which is of paramount importance.

Disseminated gonococcal infection during two decades in the university hospital, Thailand.

Background: Disseminated gonococcal infection (DGI) caused by Neisseria gonorrhoeae commonly presents with the classic triad of polyarthritis, tenosynovitis, and dermatitis. There is no clinical and microbiological data of DGI in Thailand. Objective: To study the clinical features, outcomes of treatments, and antimicrobial susceptibility data of DGI patients. Methods: All medical records of DGI patients at King Chulalongkorn Memorial Hospital (KCMH) from January 2002 through September 2019 were reviewed and analyzed. The patients were defined as definite DGI (the clinical features and the evidence of gonococcal infection) and probable DGI (clinical features with response to treatment with third-generation cephalosporins and with no evidence of gonococcal infection). Results: There were 41 patients (27 definite and 14 probable DGI), with a male-to-female ratio of 1:1.4 and median age of 30 years. The middle-age and elderly group accounted for 20% of the patients. The clinical features were fever (90.27%), arthritis (92.7%), tenosynovitis (63.4%), and genitourinary symptoms (29.3%). The most common pattern of joint involvement was oligoarthritis (52.6%). The majority of the patients had good clinical outcomes, while complications occurred in 4.8% of the patients including osteomyelitis and pyomyositis. All 19 antimicrobial-susceptibility results were susceptible to ceftriaxone. Conclusions: During the past 2 decades in KCMH, the age of the DGI patients tends to be older, and there is no gender difference as in the historical studies. The clinical features are still similar to the previous studies. The majority of the patients had good clinical outcomes. There is no case of ceftriaxone-resistant N. gonorrhoeae.

First report of abdominal sepsis caused by a recently described species: Chimaeribacter arupi.

We present a case of a 34-year-old patient with abdominal sepsis caused by an infrequent species: Chimaeribacter arupi. Genomic analysis confirmed the identification which is difficult to achieve by other methods so far. To our knowledge, this represents the first case of infection by this species reported in Argentina.

Virulence and Antimicrobial Resistance Characterization of Glaesserella parasuis Isolates Recovered from Spanish Swine Farms.

Glaesserella (Haemophilus) parasuis, the causative agent of Glässer's disease, is present in most pig farms as an early colonizer of the upper respiratory tract. It exhibits remarkable variability in virulence and antimicrobial resistance (AMR), with virulent strains capable of inducing respiratory or systemic disease. This study aimed to characterize the virulence and the AMR profiles in 65 G. parasuis isolates recovered from Spanish swine farms. Virulence was assessed using multiplex leader sequence (LS)-PCR targeting vtaA genes, with all isolates identified as clinical (presumed virulent). Pathotyping based on ten pangenome genes revealed the virulent HPS_22970 as the most frequent (83.1%). Diverse pathotype profiles were observed, with 29 unique gene combinations and two isolates carrying only potentially non-virulent pangenome genes. AMR phenotyping showed widespread resistance, with 63.3% classified as multidrug resistant, and high resistance to clindamycin (98.3%) and tylosin (93.3%). A very strong association was found between certain pathotype genes and AMR phenotypes, notably between the virulent HPS_22970 and tetracycline resistance (p < 0.001; Φ = 0.58). This study reveals the wide diversity and complexity of G. parasuis pathogenicity and AMR phenotype, emphasizing the need for the targeted characterization of clinical isolates to ensure appropriate antimicrobial treatments and the implementation of prophylactic measures against virulent strains.

Rapid Phenotypic and Genotypic Antimicrobial Susceptibility Testing Approaches for Use in the Clinical Laboratory.

The rapid rise in increasingly resistant bacteria has become a major threat to public health. Antimicrobial susceptibility testing (AST) is crucial in guiding appropriate therapeutic decisions and infection prevention practices for patient care. However, conventional culture-based AST methods are time-consuming and labor-intensive. Therefore, rapid AST approaches exist to address the delayed gap in time to actionable results. There are two main types of rapid AST technologies- phenotypic and genotypic approaches. In this review, we provide a summary of all commercially available rapid AST platforms for use in clinical microbiology laboratories. We describe the technologies utilized, performance characteristics, acceptable specimen types, types of resistance detected, turnaround times, limitations, and clinical outcomes driven by these rapid tests. We also discuss crucial factors to consider for the implementation of rapid AST technologies in a clinical laboratory and what the future of rapid AST holds.

Comparing the activity of broad-spectrum beta-lactams in combination with aminoglycosides against VIM-producing Enterobacteriaceae.

Metallo-beta-lactamase (MBL)-producing carbapenem-resistant Enterobacteriaceae (CRE) infections continue to pose a serious threat to healthcare. Due to their unique active site, MBLs evade the activity of many novel beta-lactam/beta-lactamase inhibitor combinations, which have been specifically targeted toward those carbapenemases with serine active sites. Furthermore, resistance to most, if not all, other clinically relevant antimicrobial classes leaves few reliable therapeutic options. Combination therapy has thus played a vital role in the treatment of MBL-producing CRE infections. In this study, we utilized the static time-kill assay to investigate clinically relevant concentrations of cefepime, piperacillin-tazobactam, and meropenem alone and in combination with either amikacin or the novel plazomicin to determine if combinations of routinely used beta-lactam therapy with an aminoglycoside would achieve bactericidal activity against eight clinically isolated Verona integron-encoded MBL (VIM)-producing CRE. Furthermore, we compared this activity to the combination of aztreonam/avibactam, which has shown potent activity against MBL-producing CRE. Both aztreonam/avibactam and meropenem with either aminoglycoside were rapidly bactericidal within 4 hours and remained bactericidal through 24 hours against all isolates with few exceptions. Combinations including cefepime and piperacillin-tazobactam were also rapidly bactericidal, but activity after 24 hours was inconsistent depending upon the partner aminoglycoside and isolate. Further investigation is warranted to elucidate optimal antibiotic exposures against MBL-producing CRE, including novel agents in the pipeline.IMPORTANCECarbapenem-resistant Enterobacterales (CRE) are one of the most pressing antimicrobial-resistant threats at present. In addition to exhibiting resistance to many, if not all, commonly used antimicrobial agents, CRE achieves these resistant phenotypes through a variety of mechanisms, each of which can uniquely affect available treatment options. The present study is an in vitro investigation of several Verona integron-encoded metallo-beta-lactamase (VIM)-producing CRE isolated from patients at our academic medical center. Because metallo-beta-lactamases (MBLs) are inherently resistant to many of the novel treatments designed to treat CRE due to their different active site composition, we tested several antimicrobial combinations containing routinely utilized broad-spectrum beta-lactams and aminoglycosides. Our results further our understanding of combination therapy options against VIM-producing CRE, including with non-carbapenem-beta-lactams cefepime and piperacillin. By optimizing combinations of existing antimicrobial agents, we hope to expand the available armamentarium against these resistant pathogens.

Antimicrobial Susceptibility and Genetic Epidemiology of Extended-Spectrum ß-Lactamase-Positive Enterobacterales Clinical Isolates in Central Poland.

The extended-spectrum ß-lactamases (ESßLs) are bacterial enzymes capable of hydrolyzing penicillins, cephalosporins, and aztreonam. The prevalence of ESßL is increasing among clinically significant microorganisms worldwide, drastically reducing the therapeutic management of infectious diseases. The study aimed to determine the drug susceptibility of ESßL-positive clinical isolates acquired from patients hospitalized in Lodz, central Poland, and analyze the prevalence of specific genes, determining acquired resistance in these bacteria. The samples of ESßL-positive clinical isolates were gathered in 2022 from medical microbiological laboratories in the city of Lodz, central Poland. The strains were subjected to biochemical identification and antimicrobial susceptibility testing following EUCAST guidelines. The presence of studied genes (blaCTX-M, blaSHV, blaTEM, blaPER, blaVEB) was confirmed by PCR. Over 50% of studied isolates were resistant to gentamicin, cefepime, ceftazidime and ciprofloxacin. The most common ESßL gene was blaCTX-M. In most isolates, the resistance genes occurred simultaneously. The blaPER was not detected in any of the tested strains. ESßL-producing strains are largely susceptible to the currently available antibiotics. The observation of the coexistence of different genes in most clinical isolates is alarming.

Trends in the antimicrobial susceptibility among Chinese neonates from 2012 to 2021: a multicenter study.

BACKGROUND: Antibiotic resistance is a serious global public health issue. However, there are few reports on trends in antimicrobial susceptibility in Chinese neonates, and most of the existing evidence has been derived from adult studies. We aimed to assess the trends in antimicrobial susceptibility of common pathogens in full-term neonates with invasive bacterial infections (IBIs) in China. METHODS: This cross-sectional survey study analyzed the antimicrobial susceptibility in Chinese neonates with IBIs from 17 hospitals, spanning from January 2012 to December 2021. Joinpoint regression model was applied to illustrate the trends and calculate the average annual percentage change (AAPC). Using Mantel-Haenszel linear-by-linear association chi-square test, we further compared the antibiotic minimum inhibitory concentrations (MICs) by pathogens between 2019 and 2021 to provide precise estimates of changes. RESULTS: The proportion of Escherichia coli with extended-spectrum-beta-lactamase-negative strains increased from 0.0 to 88.5% (AAPC = 62.4%, 95% confidence interval (CI): 44.3%, 82.9%), with two breakpoints in 2014 and 2018 (p-trend < 0.001). The susceptibility of group B Streptococcus (GBS) to erythromycin and clindamycin increased by 66.7% and 42.8%, respectively (AAPC = 55.2%, 95% CI: 23.2%, 95.5%, p-trend = 0.002; AAPC = 54.8%, 95% CI: 9.6%, 118.6%, p-trend < 0.001), as did Staphylococcus aureus to penicillin (AAPC = 56.2%; 95% CI: 34.8%, 81.0%, p-trend < 0.001). However, the susceptibility of Enterococcus spp. to ampicillin declined from 100.0 to 25.0% (AAPC = - 11.7%, 95% CI: - 15.2%, - 8.1%, p-trend < 0.001), and no significant improvement was observed in the antibiotic susceptibility of Escherichia coli to ampicillin, gentamicin, and cephalosporin. Additionally, the proportion of GBS/Staphylococcus aureus with relatively low MIC values for relevant antibiotics also increased in 2021 compared to 2019. CONCLUSIONS: Antimicrobial susceptibility of the most prevalent pathogens in full-term neonates seemed to have improved or remained stable over the last decade in China, implying the effectiveness of policies and practice of antibiotic stewardship had gradually emerged.