High Antimicrobial Resistance Research Articles

Salmonella Typhi whole genome sequencing in Rwanda shows a diverse historical population with recent introduction of haplotype H58.

Salmonella enterica serovar Typhi (S. Typhi) is the cause of typhoid fever, presenting high rates of morbidity and mortality in low- and middle-income countries. The H58 haplotype shows high levels of antimicrobial resistance (AMR) and is the dominant S. Typhi haplotype in endemic areas of Asia and East sub-Saharan Africa. The situation in Rwanda is currently unknown and therefore to reveal the genetic diversity and AMR of S. Typhi in Rwanda, 25 historical (1984-1985) and 26 recent (2010-2018) isolates from Rwanda were analysed using whole genome sequencing (WGS). WGS was locally implemented using Illumina MiniSeq and web-based analysis tools, thereafter complemented with bioinformatic approaches for more in-depth analyses. Whereas historical S. Typhi isolates were found to be fully susceptible to antimicrobials and show a diversity of genotypes, i.e 2.2.2, 2.5, 3.3.1 and 4.1; the recent isolates showed high AMR rates and were predominantly associated with genotype 4.3.1.2 (H58, 22/26; 84,6%), possibly resulting from a single introduction in Rwanda from South Asia before 2010. We identified practical challenges for the use of WGS in endemic regions, including a high cost for shipment of molecular reagents and lack of high-end computational infrastructure for the analyses, but also identified WGS to be feasible in the studied setting and giving opportunity for synergy with other programs.

A global genomic analysis of Salmonella Concord reveals lineages with high antimicrobial resistance in Ethiopia

Antimicrobial resistant Salmonella enterica serovar Concord (S. Concord) is known to cause severe gastrointestinal and bloodstream infections in patients from Ethiopia and Ethiopian adoptees, and occasional records exist of S. Concord linked to other countries. The evolution and geographical distribution of S. Concord remained unclear. Here, we provide a genomic overview of the population structure and antimicrobial resistance (AMR) of S. Concord by analysing genomes from 284 historical and contemporary isolates obtained between 1944 and 2022 across the globe. We demonstrate that S. Concord is a polyphyletic serovar distributed among three Salmonella super-lineages. Super-lineage A is composed of eight S. Concord lineages, of which four are associated with multiple countries and low levels of AMR. Other lineages are restricted to Ethiopia and horizontally acquired resistance to most antimicrobials used for treating invasive Salmonella infections in low- and middle-income countries. By reconstructing complete genomes for 10 representative strains, we demonstrate the presence of AMR markers integrated in structurally diverse IncHI2 and IncA/C2 plasmids, and/or the chromosome. Molecular surveillance of pathogens such as S. Concord supports the understanding of AMR and the multi-sector response to the global AMR threat. This study provides a comprehensive baseline data set essential for future molecular surveillance.

Abstract 69: Prevalence of Antimicrobial Resistance in Gram-Negative Bacteria Isolated From Cancer Patients: A Retrospective Descriptive Study

Abstract Purpose: Antimicrobial resistance (AMR) in cancer patients increases the frequency of sepsis, mortality and sepsis-associated costs of care, being the greatest public health threats of our time. The prevalence of AMR in cancer patients is 40% in those admitted to the ICU, accounting for direct health care costs of at least $20 billion (about $62 per person in the US). By 2050, AMR infections are expected to be the leading cause of death, but cancer patients are disproportionately impacted, therefore, this study’s objective was to determine the AMR prevalence of Gram-negative bacterial (GNB) isolated from clinical specimens at the hospital (Incan) of Liga Nacional Contra El Cancer in Guatemala. Methods: A retrospective descriptive study was conducted on AMR profiles of GNB clinical isolates (n=512), and gram positive (n=121) between the years 2017 to 2019. Data were extracted from the laboratory information system in the hospital. The GNB organisms (i.e., Escherichia coli, Pseudomonas aeruginosa, Enterobacter, Proteus, Acinetobacter baumannii) were isolated from inpatients to the main locations at the hospital. Results: AMR prevalence was 74.05% against ampicillin, 40.46% for amoxicillin clavulanate, 63.16% for cefoxitin, 60.54% for cefotaxime, 44.89% for cefazolin, 40.99% for ceftazidime, 13.17% for ceftriaxone, 24.83% for Ciprofloxacin, 18.8% for levofloxacin, 11.21% for Meropenem, 16.22% for Imipenem, 51.21% for gentamicin, 58.06% for amikacin, 65.28% for Trimethoprim sulfamethoxazole, 53.06% for Doxycycline, 32.64% for Fosfomycin, 42.65% for Aztreonam, 30.91% for clindamycin, 0.35% for Linezolid, 49.71% for nitrofurantoin, 40.17% for Erythromycin respectively across the GNB pathogens. For specific pathogens, Pseudomona aeruginose showed 94.87% and 94.74% of resistance for ampicillin and cefotaxime respectively. E. coli resistance showed 32.28% and 61.54% for ciprofloxacin and Imipenem respectively. Enterobacter resistance was 40.38% for gentamicin. Pseudomona aeruginose showed 88.89% resistance for Doxycycline. Lastly, nitrofurantoin resistance was 100% for Acinetobacter, 93.85% for Pseudomona aeruginose, and 66.67% for Proteus Species. Conclusions: High AMR was found among common Gram-negative bacteria at this oncology hospital. Monitoring data on antimicrobial susceptibility of common bacterial organisms is critical for assessing trends in AMR to inform stakeholders to reinforce policy decisions of antibiotic prescription at national level. Citation Format: Angel Velarde, Nneka Molokwu, Karla Escobar, Vicky de Falla, Alba Kihn, Carlos García Reynoso, Javier Figueroa Moraga. Prevalence of Antimicrobial Resistance in Gram-Negative Bacteria Isolated From Cancer Patients: A Retrospective Descriptive Study [abstract]. In: Proceedings of the 11th Annual Symposium on Global Cancer Research; Closing the Research-to-Implementation Gap; 2023 Apr 4-6. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(6_Suppl):Abstract nr 69.

Respiratory bacterial co-infections and their antibiotic resistance pattern in COVID-19 patients at a tertiary care centre in India.

Patients with coronavirus disease-2019 (COVID-19) are prone to develop respiratory bacterial infections irrespective of their need for mechanical ventilatory support. Information about the incidence of concomitant respiratory bacterial infections in COVID- 19 patients from India is limited. This study aimed to determine the incidence of concomitant respiratory bacterial pathogens and their drug resistance in these patients. A prospective study was performed by including patients who were admitted to our tertiary care centre from March 2021 to May 2021 to evaluate secondary bacterial respiratory co-infections in patients via real-time PCR (RT-PCR)-confirmed cases of COVID-19 disease caused by SARS CoV-2. Sixty-nine culture-positive respiratory samples from patients with COVID-19 were incorporated into this study. The most commonly isolated bacterial microorganisms were Klebsiella pneumoniae (23 samples, 33.33 %) and Acinetobacter baumannii (15, 21.73 %), followed by Pseudomonas aeruginosa (13, 18.84 %). Among the microorganisms isolated, 41 (59.4 %) were multidrug-resistant (MDR) and nine (13 %) were extensively drug-resistant (XDR). Among the Gram-negative bacteria isolated, K. pneumoniae showed high drug resistance. Fifty carbapenem-resistant microorganisms were isolated from the patients included in our study. Concerning the hospital stay of the patients enrolled, there was an increased length of intensive care unit stay, which was 22.25±15.42 days among patients needing mechanical ventilation in comparison to 5.39±9.57 days in patients on ambient air or low/high-flow oxygen. COVID-19 patients need increased length of hospitalization and have a high incidence of secondary respiratory bacterial infections and high antimicrobial drug resistance.

Epidemiological and Antimicrobial Resistant Patterns, and Molecular Mechanisms of Carbapenem-Resistant Klebsiella pneumoniae Infections in ICU Patients.

To study the epidemiological and antimicrobial resistant patterns, clinical characteristics and risk factors of critically ill patients infected with carbapenem-resistant Klebsiella pneumoniae (CRKP) from intensive care units (ICUs). The potential molecular mechanisms of antimicrobial resistance and virulence of CRKP were investigated through evaluation of associated genes. Totally, 201 ICU patients infected with K. pneumoniae were recruited from January 2020 through January 2021. K. pneumoniae strains were collected from diverse clinical specimens and identified by microbial cultures and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Antimicrobial resistance was measured through broth micro-dilution or Kirby-Bauer assays. The carbapenemase-, virulence-, and capsular serotype-associated genes of CRKP were individually detected by PCR and sequencing. Demographic and clinical profiles were acquired from hospital databases to evaluate the correlation of CRKP infection incidence with clinical risk factors. Of the 201 K. pneumoniae strains, CRKP accounted for 41.29%. Seasonal bias existed in local prevalence of CRKP infections. CRKP strains mounted significantly strong resistance against major antimicrobial agents except ceftazidime-avibactam, tigecycline and minocycline. Recent exposure to certain antibiotics and prior treatment with invasive interventions were prone to increase CRKP infection risks with worsened infectious outcomes. The local top carbapenemase-encoding and virulence-associated genes of CRKP were blaKPC and irp2, respectively. Nearly half of CRKP isolates harbored a capsular polysaccharide serotype of K14.K64 (wzi-64) which preferentially emerged in the cohort with worse outcomes of infection. Featured epidemiology and typical clinical characteristics existed extensively in K. pneumoniae infections among ICU patients. The CRKP cohort exhibited substantially high antimicrobial resistance. Distinctive carbapenemase-, virulence-, and serotype-associated genes were intensively involved in the spread and pathogenesis of CRKP. These findings supported careful management of critically ill patients potentially infected with virulent CRKP in the ICUs.

Ongoing Strategies to Improve Antimicrobial Utilization in Hospitals across the Middle East and North Africa (MENA): Findings and Implications.

Antimicrobial resistance (AMR) is an increasing global concern, increasing costs, morbidity, and mortality. National action plans (NAPs) to minimize AMR are one of several global and national initiatives to slow down rising AMR rates. NAPs are also helping key stakeholders understand current antimicrobial utilization patterns and resistance rates. The Middle East is no exception, with high AMR rates. Antibiotic point prevalence surveys (PPS) provide a better understanding of existing antimicrobial consumption trends in hospitals and assist with the subsequent implementation of antimicrobial stewardship programs (ASPs). These are important NAP activities. We examined current hospital consumption trends across the Middle East along with documented ASPs. A narrative assessment of 24 PPS studies in the region found that, on average, more than 50% of in-patients received antibiotics, with Jordan having the highest rate of 98.1%. Published studies ranged in size from a single to 18 hospitals. The most prescribed antibiotics were ceftriaxone, metronidazole, and penicillin. In addition, significant postoperative antibiotic prescribing lasting up to five days or longer was common to avoid surgical site infections. These findings have resulted in a variety of suggested short-, medium-, and long-term actions among key stakeholders, including governments and healthcare workers, to improve and sustain future antibiotic prescribing in order to decrease AMR throughout the Middle East.

Surveillance of antibiotic persistence adaptation of emerging antibiotic-resistant bacteria in wastewater treatment processes: Comparison between domestic and hospital wastewaters

This study aims to investigate the survival and antimicrobial resistance (AMR) adaptation of the emerging antibiotic-resistant bacteria (ARB) in a common wastewater treatment process (activated sludge (AS) + chlorination (if any)) treating domestic and hospital wastewater in Thailand. The selected Gram-negative AMR indicators were E. coli (EC), coliforms (CF), and Acinetobacter spp. (AC) which resist carbapenem and extended spectrum beta-lactamase (ESBL). Meanwhile, the selected Gram-positive ARBs were methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). The viable population of those ARB was enumerated via standard plate count using selective/differential media comparison between added antibiotic (resistant population) and none (total population). The results showed that E. coli, coliforms, Acinetobacter spp., S. aureus, and Enterococci spp. appeared in similar ranges (4.20 – 5.05 log CFU ml −1) in both types of wastewaters. The ESBL resistance population of EC, CF, AC; and MRSA appeared similarly in both types of wastewaters. However, the ARB percentages of carbapenem resistance of EC, CF, and AC including VRE were higher in the hospital wastewater. In treatment processes, all ARB could survive in AS processes differently, but only MRSA, carbapenem- and ESBL-resistant Acinetobacter spp. might reproduce in the aeration tanks. Moreover, carbapenem and ESBL-resistant Acinetobacter spp., MRSA, and VRE showed remarkably high AMR prevalences in the chlorinated effluent. The findings suggest that carbapenem- and ESBL-resistant Acinetobacter spp., MRSA, and VRE could be the AMR indicators of hospital-discharged wastewater.

Antibiotic Susceptibility, Biofilm-Forming Ability, and Prevalence of Extended-Spectrum Beta-Lactamase (ESBL)- and Biofilm-Associated Genes Among Klebsiella pneumoniae Isolates from Hospitalized Patients in Northwest of Iran

Klebsiella pneumoniae is an opportunistic bacterium, which is globally recognized for its high prevalence and antimicrobial resistance (AMR). Biofilm-forming capability, susceptibility testing, and phenotypic confirmatory test for extended-spectrum beta-lactamase (ESBL)-producing isolate recognition of 104K. pneumoniae isolates were performed according to the Clinical Laboratory Standard Institute (CLSI) guidelines. The prevalence of ESBL-associated genes bla-VIM, bla-NDM, and bla-OXA-48, as well as biofilm-associated genes luxS, fimH1, wza, and mrkD, was determined by multiplex PCR. The highest resistance rate was against ampicillin (100.0%). Among the 104K. pneumoniae isolates, 52 (50.0%) and 31 (29.8%) isolates were determined as multi- and extensively drug resistant (MDR, XDR), respectively. Moreover, 21 (40.4%) isolates were determined as ESBL producing. Among 50 biofilm-producing K. pneumoniae isolates, 7 (14.0%), 15 (30.0%), and 28 (56.0%) isolates exhibited high, moderate, and weak levels of biofilm formation, respectively. A number of 41 (78.8%) isolates were susceptible to colistin, and 10 (19.2%) were resistant. AMR was significantly higher (P < 0.05) in the biofilm-forming isolates compared with non-biofilm formers.

Typhoid Fever Surveillance, Incidence Estimates, and Progress Toward Typhoid Conjugate Vaccine Introduction - Worldwide, 2018-2022.

Typhoid fever, an acute febrile illness caused by Salmonella enterica serovar Typhi (S. Typhi), is endemic in many low- and middle-income countries† (1). In 2015, an estimated 11-21 million typhoid fever cases and 148,000-161,000 associated deaths occurred worldwide (2). Effective prevention strategies include improved access to and use of infrastructure supporting safe water, sanitation, and hygiene (WASH); health education; and vaccination (1). The World Health Organization (WHO) recommends programmatic use of typhoid conjugate vaccines for typhoid fever control and prioritization of vaccine introduction in countries with the highest typhoid fever incidence or high prevalence of antimicrobial-resistant S. Typhi (1). This report describes typhoid fever surveillance, incidence estimates, and the status of typhoid conjugate vaccine introduction during 2018-2022. Because routine surveillance for typhoid fever has low sensitivity, population-based studies have guided estimates of case counts and incidence in 10 countries since 2016 (3-6). In 2019, an updated modeling study estimated that 9.2 million (95% CI = 5.9-14.1) typhoid fever cases and 110,000 (95% CI = 53,000-191,000) deaths occurred worldwide, with the highest estimated incidence in the WHO South-East Asian (306 cases per 100,000 persons), Eastern Mediterranean (187), and African (111) regions (7). Since 2018, five countries (Liberia, Nepal, Pakistan, Samoa [based on self-assessment], and Zimbabwe) with estimated high typhoid fever incidence (≥100 cases per 100,000 population per year) (8), high antimicrobial resistance prevalence, or recent outbreaks introduced typhoid conjugate vaccines into their routine immunization programs (2). To guide vaccine introduction decisions, countries should consider all available information, including surveillance of laboratory-confirmed cases, population-based and modeling studies, and outbreak reports. Establishing and strengthening typhoid fever surveillance will be important to measure vaccine impact.

Emergence and Inter- and Intrahost Evolution of Pandrug-Resistant Klebsiella pneumoniae Coharboring tmexCD1-toprJ1, blaNDM-1, and blaKPC-2.

Klebsiella pneumoniae is capable of acquiring various exogenous genetic elements and subsequently conferring high antimicrobial resistance. Recently, a plasmid-mediated RND family multidrug efflux pump gene cluster, tmexCD1-toprJ1, was discovered in K. pneumoniae. In this study, we analyzed tigecycline-resistant K. pneumoniae isolates from patients from surveillance from 2017 to 2021. In addition to phenotype detection, including growth curves, plasmid transferability and stability, hypermucoviscosity, biofilm formation, and serum survival, by whole-genome sequencing, we analyzed the phylogenetic relationships of the isolates harboring tmexCD1-toprJ1 and discovered the composition of plasmids carrying tmexCD1-toprJ1. In total, we discovered that 12 tigecycline-resistant isolates from 5 patients possessed tmexCD1-toprJ1, designated sequence type 22 (ST22) and ST3691. An ST11 isolate harbored a partial tmexD1, and a complete toprJ1 (tmexC1 was lost) was tigecycline sensitive. All the ST22 tigecycline-resistant isolates coharbored tmexCD1-toprJ1, blaNDM-1, and blaKPC-2. tmexCD1-toprJ1 was encoded by a novel IncU plasmid in ST22 and an IncFIB/HI1B plasmid in ST3691, which presented differences in mobility and stability. Interestingly, isolates from the same patients presented heteroresistance to tigecycline, not only among isolates from different specimens but also those from the same sample, which might be attributed to the differential expression of tmexCD1-toprJ1 due to the dynamic genetic heterogeneity caused by relocating tmexCD1-toprJ1 close to the replication origin of plasmid. Here, we reported the emergence of K. pneumoniae isolates coharboring tmexCD1-toprJ1, blaNDM-1, and blaKPC-2. The results highlight the impact of in vivo genetic heterogeneity of tmexCD1-toprJ1-carrying elements on the in vivo variation of tigecycline resistance, which might have notable influences on antimicrobial treatment. IMPORTANCE Pandrug-resistant (PDR) Klebsiella pneumoniae poses a great challenge to public health, and tigecycline is an essential choice for antimicrobial treatment. In this study, we reported the emergence of PDR K. pneumoniae coharboring tmexCD1-toprJ1, blaNDM-1, and blaKPC-2, which belongs to ST22 and ST3691. By whole-genome analysis, we reconstructed the evolutionary map of the ST22 ancestor to become the PDR superbug by acquiring multiple genetic elements encoding tmexCD1-toprJ1 or blaNDM-1. Importantly, the genetic contexts of tmexCD1-toprJ1 among the ST22 isolates are different and present with various mobilities and stabilities. Furthermore, we also discovered the heterogeneity of tigecycline resistance during long-term infection of ST22, which might be attributed to the differential expression of tmexCD1-toprJ1 due to the dynamic genetic heterogeneity caused by relocating tmexCD1-toprJ1 close to the replication origin of plasmid. This study tracks the inter- and intrahost microevolution of the superbug PDR K. pneumoniae and highlights the importance of timely monitoring of the variation of pathogens during antimicrobial treatment.

Intestinal Carriage of Extended Spectrum Beta-Lactamase-Producing Salmonella enterica from Chickens and Poultry Farmers in Dschang, in the Western Region of Cameroon

Salmonella enterica is the principal causative agent of salmonellosis, a threat to human health. Because of its high antimicrobial resistance potential, Salmonella enterica has become worrisome, mostly in developing countries where hygiene and antimicrobial usage are defective. This study aimed to determine the epidemiology of the intestinal carriage of Extended Spectrum β-Lactamase producing Salmonella enterica from chickens and poultry farmers in Dschang, a town in the western region of Cameroon. A total of 416 chickens and 72 farmers were sampled between May and October 2020; and Salmonella enterica were isolated and subjected to extended spectrum β-lactamase screening. Logistic regression was used to test for statistical associations using a p-value of ≤0.05. Results from this study revealed that the prevalence of the intestinal carriage of Salmonella enterica for chickens and farmers were 55.77% [51.00; 60.54] and 22.22% [12.62; 31.82], respectively. Meanwhile, the intestinal carriage of Extended Spectrum β-Lactamase producing Salmonella enterica was 23.08% [13.76; 32.40] and 5.55% [0.26; 10.84] from chickens and poultry farmers, respectively. The risk factor for this carriage was revealed to be lack of knowledge by actors in livestock industries of antibiotic resistance. Chickens, just like poultry farmers, represent the starting point of community salmonellosis, which is difficult to cure; therefore, sensitization of breeders is an effective tool for the mitigation of this burden.

Helicobacter Pylori Infection in Children with the Rescue Therapy; A Case Report

Background: Helicobacter pylori infection affects more than half of the world population and it occurs generally in childhood. Risk factors include residence in a developing country, poor socio-economic status, overcrowding family, ethnic and genetic predisposition. There is a difficulty eradicating this bacterium due to its high antimicrobial resistance. We aim to discuss enforcement and management of Helicobacter pylori infection in children. Case Presentation: A 5 year 10 months old girl diagnosed with recurrent abdominal pain due to Helicobacter pylori infection. The patient often had recurrent abdominal pain located specifically on epigastrium area. Laboratory findings demonstrated H. pylori IgM positive and negative IgG level. The result of endoscopy and biopsy revealed gastritis and mild intestinal metaplasia and moderate Helicobacter pylori density. The patient still experienced abdominal pain despite the standard therapy, and later received rescue therapy. Conclusion: Eradication of H. pylori was failed with standard therapy and continued with rescue therapy. Keywords: Helicobacter pylori infection, rescue therapy, standard therapy, case report.

In silico discovering relationship between bacteriophages and antimicrobial resistance

Bacteriophages and their potential contribution to antimicrobial resistance (AMR) have attracted growing attention in the context of medicine and pharmaceutics. A major objective of the CAMDA challenge is to acquire more knowledge about the relationship between viruses, their hosts and AMR genes in determining if AMR indeed can spread through phages. This study is focused on exploring the relationship and possible dependencies between bacteriophages and AMR based on the data collected from urban environments all over the world. The samples in the data are classified into two categories: high and low, according to the observed levels of AMR genes. The approach used in our analyses consists of several different methods which assess the differential abundance of phages, their diversity across samples, the impact on AMR categories and associations with AMR genes. The relationship between phages, their hosts and AMR is also explored by a Bayesian spatial model, using the AMR category (low vs high) as a factor. We found a higher relative risk for phages known to infect Staphylococcus aureus alone or both S. aureus and Acinetobacter baumannii in the high AMR group, which implies that these phages may have a role in the dissemination of antimicrobial genes.

Antimicrobial resistance-associated mutations in chromosomal genes of ESKAPE pathogens

The worldwide successful expansion of ESKAPE pathogens is largely due to their ability to rapidly acquire high antimicrobial resistance levels. The bacterial resistome includes (1) plasmid-encoded genes acquired as a result of horizontal gene transfer, and (2) chromosomal genes associated with the antimicrobial resistance development. This review represents the priority list of the ESKAPE group chromosomal genes, mutations in which are associated with antimicrobial resistance. The diversity of chromosomal genes carrying antimicrobial resistance (AMR) associated mutations confers the rapid pathogen adaptation to antimicrobials by generation of multilevel pathways to neutralize antibiotics. Analysis of the AMR mechanisms associated only with plasmid resistance genes is insufficient. A comprehensive description of AMR mechanisms should include also an analysis of chromosomal genes, mutations in which lead to increased levels of antimicrobial resistance.

Usefulness of EUCAST rapid antibiotic susceptibility breakpoints and screening cut-off values directly from blood cultures for the inference of β-lactam resistance mechanisms in Enterobacterales.

Reducing the turnaround time for reporting antimicrobial susceptibility testing (AST) results is important for adjusting empirical treatments and may impact clinical outcomes of septic patients, particularly in settings with high antimicrobial resistance. Disc diffusion could be useful for inferring β-lactam resistance mechanisms. To evaluate the usefulness of EUCAST rapid AST (RAST) disc diffusion breakpoints for the screening of resistance mechanisms (sRAST) and interpretive reading of resistance phenotypes to infer ESBL and carbapenemases production in Enterobacterales. Blood cultures were artificially spiked with Enterobacterales clinical isolates with well-characterized β-lactam resistance mechanisms (n = 93), WT phenotypes (n = 26) and ATCC strains (n = 8). AST was performed by disc diffusion directly from blood cultures and inhibition zones were manually measured at 4, 6 and 8 h. To infer the presence of resistance mechanisms, EUCAST RAST breakpoints and screening cut-off values (sRAST) combined with the double-disc synergy test (DDS) for ESBLs or aztreonam susceptibility for carbapenemases detection were used. DDS together with sRAST detected all ESBL producers as early as at 4 h incubation. Cefotaxime was the antibiotic with the highest discriminatory power. The suspicion of carbapenemase production by sRAST at 8 h was possible in 73% of Klebsiella pneumoniae and in 100% of Escherichia coli carbapenemase-producing isolates. Phenotypic analysis improves the detection of some low hydrolytic carbapenemases (OXA-48 or KPC-3 mutants). Early detection of β-lactam resistance mechanisms directly from positive blood cultures was possible using sRAST together with the interpretive reading of antibiotic resistance phenotypes. Some carbapenemase types such as OXA-48 might be difficult to infer. Screening-positive isolates should be confirmed using an alternative technique.

Prevalence and whole-genome analysis of multidrug-resistant Salmonella isolated from chicken carcasses in Hanoi

Salmonella enterica is one of the most dangerous food-borne pathogens posing a significant global concern especially to travelers returning from developing countries. Given that chicken is the main reservoir for Salmonella, the emergence and spread of multi-drug resistant Salmonella from chicken have not been fully described in Vietnam. The present study aimed to evaluate the phenotypic and genotypic antimicrobial resistances of Salmonella from chicken carcasses. Among 104 raw chickens collected from 5 districts in Hanoi city, 65 samples were contaminated with Salmonella of which the highest contamination rate was found in Thanh Xuan. A total of 63/65 (96.9%) of Salmonella isolates were resistant to at least one antibiotic and 61/65 (93.9%) of the isolates were found to be multidrug resistant. Whole-genome sequencing was employed to analyze 4 strains with high (12_S2 and 61_S18) and low (19_S4 and 8_S1) antimicrobial resistance patterns. Genomic analysis indicated the presence of 27 genes conferring antibiotic resistance. Genotypes were highly correlated to observed phenotypes in 4 strains. Importantly, extended-spectrum β-lactamase blaCTX-M-55 and colistin resistance mcr-3 were reported in isolates of Salmonella enterica serovar Typhimurium. This is the first report showing the prevalence and genome sequences of Salmonella from chicken carcasses collected in Hanoi, Vietnam. The results represented herein provided the basis to understand the dynamics of antibiotic resistance of Salmonella in Vietnam and to spot antimicrobial resistance determinants for early diagnosis.

Antimicrobial activity of organic acids against canine skin bacteria.

Canine skin is often a source of bacterial strains that are characterized by the presence of important virulence factors and a high antimicrobial resistance. These bacteria are involved in the pathogenesis of infectious skin diseases, which are very frequent in dogs. Moreover, canine skin isolates are easily spread to other animals and humans. The aim of this study was to evaluate the inhibitory and bactericidal activity of eight organic acids (L-lactic, acetic, propionic, butyric, citric, succinic, glycolic, L-ascorbic acid) against 14 canine skin isolates (11 Gram-positive and three Gram-negative species). The advantages of the tested organic acids are their gentleness to the skin and their affordability. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the broth microdilution method. All tested acids showed a bactericidal effect against the selected bacteria, with the exception of their bacteriostatic effect against the Bacillus cereus strain. The lowest MIC showed acetic acid (MIC between 0.5 and 2.0mg/mL) and propionic acid (MIC 0.8 - 3.3mg/mL), whereas L-ascorbic acid (MIC 4.0 - 16.0mg/mL) seems to be weaker among the tested acids. Two Staphylococcus aureus strains and a strain of Escherichia coli were observed to be more resistant compared to coagulase-negative staphylococci.

Biofilm Formation by Staphylococcus epidermidis and Its Inhibition Using Carvacrol, 2-Aminobenzemidazole, and 3-Indole Acetonitrile.

Biofilm-associated bacterial infections are problematic for physicians due to high antimicrobial resistance in biofilm-forming bacteria. Staphylococcus species, particularly Staphylococcus epidermidis, cause severe infections particularly associated with clinical implants. In this study, we have detected the biofilm formation potential of clinical S. epidermidis isolates using phenotypic and genotypic approaches in nutrient-rich and nutrient-deficient growth conditions. The Congo red agar method determined the biofilm formation potential with limited efficacy. However, the tissue culture plate method adroitly classified the isolates as strong, moderate, weak, and non-biofilm producers with five (10%) of the isolates as strong biofilm producers. Ten biofilm-associated genes were targeted, and the fruA gene was found to be the most prevalent (20%). Three antibiofilm compounds, carvacrol, 2-aminobenzemidazole, and 3-indole acetonitrile, were assessed against strong biofilm-producing S. epidermidis isolates. To the best of our knowledge, this is the first report of genotypic and phenotypic detection of biofilms formed by clinical S. epidermidis isolates from this region. The use of 3-indole acetonitrile against these biofilms and toluene as a solvent is novel. The study highlights the significance of biofilm and antibiofilm potential of the studied compounds for effective treatment and control of S. epidermidis infections.

1757. Regional distribution of Escherichia coli antibiotic resistance among outpatients in Washington state, 2013-2019

Abstract Background Escherichia coli is the predominant pathogen of urinary tract infections in the United States. Understanding regional patterns of uropathogenic E. coli antimicrobial resistance (AMR) may help further the practice of antibiotic stewardship through the creation of region-specific antibiograms. In this study, we analyzed regional patterns of uropathogenic E. coli AMR among outpatients in Washington state. Methods Deidentified results from antibiotic susceptibility tests performed by Quest Diagnostics on Washington state outpatient isolates from 2013 through 2019 were analyzed. Only the first E. coli isolate from each patient was included in the analyses. We conducted separate relative risk regressions with robust standard errors for five antibiotics (ampicillin [AMP], ciprofloxacin [CIP], ceftriaxone [CRO], gentamicin [GEN], and trimethoprim/sulfamethoxazole), classified as “susceptible” or “non-susceptible.” The state is divided into nine Public Health Emergency Preparedness Regions (PHEPRs), which served as the exposures for the analysis, with adjustment for sex, year of isolate collection, and age group (0-18, 19-50, &amp;gt; 50). Results We included 40,865 isolates in the study (93% female, mean age 47 years). Compared to the Central PHEPR (containing Seattle), most other regions had significantly lower adjusted relative risks (aRR) of AMR; no regions had significantly higher aRR of resistance for any of the five antibiotics. Differences in resistance between Central and other regions varied by antibiotic. Regional AMR differences were largest for CRO (low aRRs compared to Central) and smallest for AMP. Other patterns observed include a lower aRR of AMR for females compared to males for AMP, CIP, CRO, and GEN; higher aRR of AMR for CRO for recent years (2015-2019) compared to 2013; and higher AMR with age for CIP and CRO. Conclusion Given the differences in resistance across Washington’s PHEPRs, antibiograms should be tailored to provide the most regionally accurate information to prescribers. The emergent situation surrounding AMR calls for more specific outpatient antibiograms to enable healthcare providers to improve health outcomes and mitigate emerging resistance to antibiotics among outpatients. Disclosures Ann Salm, PhD, Quest Diagnostics Inc.: Employed and own stock in Quest Diagnostics Inc.|Quest Diagnostics Inc.: Stocks/Bonds Hema Kapoor, MD, D(ABMM), Quest Diagnsotics: Stocks/Bonds Stephen E. Hawes, PhD, InBios International: Advisor/Consultant Jeff Radcliff, B.S., Quest Diagnostics: Employee|Quest Diagnostics: Stocks/Bonds.

The Antimicrobial Resistance (AMR) Rates of Uropathogens in a Rural Western African Area-A Retrospective Single-Center Study from Kpando, Ghana.

Little is known about the antimicrobial resistance (AMR) status of uropathogens in Western Africa. We performed a retrospective evaluation of urine cultures collected from the rural Margret Marquart Catholic Hospital, Kpando, Ghana during the time period from October 2019-December 2021. Urine samples from 348 patients (median age 40 years, 52.6% male) were examined. Of these, 125 (35.9%) showed either fungal or bacterial growth, including Escherichia coli in 48 (38.4%), Candida species (spp.) in 29 (23.2%), Klebsiella spp. in 27 (21.6%), Proteus spp. in 12 (9.6%), Citrobacter spp. in 10 (8.0%), Salmonella spp. in 4 (3.2%), Staphylococcus spp. in 3 (2.4%), and Pseudomonas spp. in 2 (1.6%) cases. Two bacterial spp. were detected in 7 samples (5.6%). Antibiotic susceptibility testing showed resistance to a mean 8.6 out of 11 tested antibiotics per patient. Significant predictors (p &lt; 0.05) of bacterial growth were age (OR 1.03), female sex (OR 3.84), and the number of pus cells (OR 1.05) and epithelial cells (OR 1.07) in urine microscopy. We observed an alarmingly high AMR rate among the uropathogens detected, even to reserve antibiotics. A similar resistance profile can be expected in West African patients living in high-income countries. These observations warrant the implementation of restrictive antibiotic protocols, together with the expansion of urine culture testing capacities, improvement of documentation and reporting of AMR rates, and continued research and development of new antibiotic therapies in order to stem the progression of AMR in this West African region.