Antibiotic Resistance Determinants Research Articles

Antibiotic Resistance in the Farming Environment

Bacterial resistance to antibiotics is now an extremely important safety and health issue. Much of the research on this phenomenon focuses on its clinical aspects, while current findings confirm that it is only one of a number of potential sources of bacteria and genes responsible for drug resistance. There are many indications that one of the main contributors to this issue is currently agriculture and that this applies virtually worldwide. Increased awareness of issues of rational use of antibiotics in husbandry practice entails increased interest in phenomena related to the spread of antibiotic resistance in the environment, their specifics, and the scale of the existing threat. This work, based on current research, analyzed selected aspects of the use of antibiotics in animal production, the presence of antibiotic-resistant microorganisms in farm animals and in waste from agricultural production, in particular from animal breeding farms, the determinants of antibiotic resistance in farming practices and the potential threats related to emissions and spread of antibiotic resistance factors in the environment, including the possibility of transfer of resistant bacteria and resistance genes to humans.

Isolation, Molecular Characterization, and Determination of Antibiotic Resistance Patterns of Lactic Acid Bacteria from Regional Yogurt Samples and their Probiotic Properties

Objectives:: This investigation aims to isolate the Lactic Acid Bacteria (LAB) from yogurt samples from the Tangail district of Bangladesh and evaluate their probiotic properties. Methods:: A rigorous study was carried out from April to August, 2019. A total of 10 samples were examined by following the standard bacteriological methods. Besides the biochemical and antibiogram tests, molecular characterization of the isolated bacteria was carried out. Results:: Ten isolates were confirmed as LAB, and they exhibited excellent probiotic properties. They were able to survive in both acidic (pH 2) and alkaline (pH 8) conditions. They also survived against phenol (0.1-0.4%) and NaCl (1-10%) after 24 h incubation. Most of the isolates harboured plasmid DNA and showed good resistance patterns against the antibiotics used. During the mating experiment, no X-conjugants were found. Conclusion:: In conclusion, the mating experiment suggested that the acquired resistant genes might be chromosome mediated, and isolates showed good probiotic properties that confer health benefits.

Fertilizing drug resistance: Dissemination of antibiotic resistance genes in soil and plant bacteria under bovine and swine slurry fertilization

The increasing global demand for food production emphasizes the use of organic animal fertilizers, such as manure and slurry, to support sustainable agricultural practices. However, recent studies highlight concerns about antibiotic resistance determinants in animal excrements, posing a potential risk of spreading antibiotic resistance genes (ARGs) in agricultural soil and, consequently, in food products.This study examines the dissemination of ARGs within the soil and plant-associated microbiomes in cherry radish following the application of swine and bovine slurry. In a 45-day pot experiment, slurry-amended soil, rhizospheric bacteria, and endophytic bacteria in radish roots and leaves were sampled and analyzed for 21 ARGs belonging to 7 Antibiotic Resistance Phenotypes (ARPs). The study also assessed slurry's impact on soil microbiome functional diversity, enzymatic activity, physicochemical soil parameters, and the concentration of 22 selected antimicrobials in soil and plant tissues.Tetracyclines and β-lactams were the most frequently identified ARGs in bovine and swine slurry, aligning with similar studies worldwide. Swine slurry showed a higher prevalence of ARGs in soil and plant-associated bacteria, particularly TET genes, reflecting pig antibiotic treatments. The persistent dominance of TET genes across slurry, soil, and plant microbiomes highlights significant influence of slurry application on gene occurrence in plant bacteria. The presence of ARGs in edible plant parts underscores health risks associated with raw vegetable consumption. Time-dependent dynamics of ARG occurrence highlighted their persistent presence throughout the experiment duration, influenced by the environmental factors and antibiotic residuals. Notably, ciprofloxacin, which was the only one antimicrobial detected in fertilized soil, significantly impacted bovine-amended variants. Soil salinity modifications induced by slurry application correlated with changes in ARG occurrence. Overall, the research underscores the complex relationships between agricultural practices, microbial activity, and antibiotic resistance dissemination, emphasizing the need for a more sustainable and health-conscious farming approaches.

Exploring antimicrobial resistance determinants in the Neanderthal microbiome.

The results of our analysis demonstrate the challenges in identifying determinants of antibiotic resistance within the endogenous microbiome of Neanderthals. Despite the comprehensive investigation of multiple studies and the utilization of advanced analytical techniques, the detection of antibiotic resistance determinants in the ancient microbial communities proved to be particularly difficult. However, our analysis did reveal the presence of some authentic ancient conservative genes, indicating the preservation of certain genetic elements over time. These findings raise intriguing questions about the factors influencing the presence or absence of antibiotic resistance in ancient microbial communities. It could be speculated that the spread of current antibiotic resistance, which has reached alarming levels in modern times, is primarily driven by anthropogenic factors such as the widespread use and misuse of antibiotics in medical and agricultural practices.

Exploring Antibiotic Resistance Gene Expression in Acinetobacter baumannii Using Microarray Technology

Background: Antibiotic resistance is a significant challenge in healthcare, particularly in nosocomial infections caused by Acinetobacter baumannii. Efflux pumps play a crucial role in mediating antibiotic resistance in A. baumannii, yet comprehensive evaluation of these pumps and acquired resistance determinants is lacking. Here, we present the development and validation of an oligonucleotide-based DNA microarray for assessing gene expression of efflux pumps and detecting acquired antibiotic resistance determinants in A. baumannii. Objective: The primary objective of this study was to develop a robust microarray platform capable of simultaneously assessing the expression of efflux pump genes and detecting acquired resistance determinants in A. baumannii. Additionally, we aimed to validate the microarray's performance using mutants overexpressing or deficient in efflux pumps and single-step mutants obtained on various antibiotics. Methods: The DNA microarray consisted of probes targeting 78 genes, including 17 efflux systems, 15 resistance determinants, and 19 housekeeping genes. Comparative analysis of mutants, along with quantitative reverse transcriptase PCR validation, was conducted to confirm the microarray's accuracy in detecting efflux pump overexpression. Results: Validation experiments revealed overexpression of RND efflux pumps AdeABC and AdeIJK in mutants obtained on gentamicin, cefotaxime, or tetracycline, as well as identification of a novel efflux pump, AdeFGH, overexpressed in a mutant exposed to chloramphenicol. Clinical isolates showed overexpression of AdeABC and chromosomally encoded cephalosporinase, along with several acquired resistance genes, accounting for the multidrug-resistant phenotype. Conclusion: The developed microarray demonstrates high sensitivity and specificity in detecting efflux pump expression and acquired resistance determinants in A. baumannii. Its potential utility in identifying antibiotic resistance and novel efflux systems highlights its importance in clinical settings.

Genomic Insights Into Enterococcus mundtii 203: A Promising Probiotic Candidate Isolated From Camel Feces.

Enterococcus, a common commensal organism in the human gut, exhibits a dual nature with certain strains offering probiotic benefits, while others are associated with nosocomial infections. In this study, we conducted a comprehensive examination of the genome of Enterococcus mundtii strain 203 to assess its probiotic potential and safety profile. The complete genome sequencing, assembly, and annotation were performed, followed by bioinformatics analysis. Our investigation reveals a detailed characterization of the Enterococcus mundtii 203 genome, originally isolated from camel feces, with a size of 3,053,234 bases and a GC content of 38.4%. Importantly, our analysis suggests that this strain poses no risk as a human pathogen due to the absence of antibiotic resistance determinants and virulence factors. The genome harbors a multitude of genes responsible for lactic acid production, bioactive peptide synthesis, adhesion molecule expression, resistance to harsh gut conditions, and enhancement of host metabolism. These findings underline the potential probiotic functionality of Enterococcus mundtii 203, positioning it as a promising candidate. Notably, our study did not identify any sequences related to insertion elements or CRISPR-Cas fragments.

Detection of florfenicol resistance in opportunistic Acinetobacter spp. infections in rural Thailand.

Florfenicol (Ff) is an antimicrobial agent belonging to the class amphenicol used for the treatment of bacterial infections in livestock, poultry, and aquaculture (animal farming). It inhibits protein synthesis. Ff is an analog of chloramphenicol, an amphenicol compound on the WHO essential medicine list that is used for the treatment of human infections. Due to the extensive usage of Ff in animal farming, zoonotic pathogens have developed resistance to this antimicrobial agent. There are numerous reports of resistance genes from organisms infecting or colonizing animals found in human pathogens, suggesting a possible exchange of genetic materials. One of these genes is floR, a gene that encodes for an efflux pump that removes Ff from bacterial cells, conferring resistance against amphenicol, and is often associated with mobile genetic elements and other resistant determinants. In this study, we analyzed bacterial isolates recovered in rural Thailand from patients and environmental samples collected for disease monitoring. Whole genome sequencing was carried out for all the samples collected. Speciation and genome annotation was performed revealing the presence of the floR gene in the bacterial genome. The minimum inhibitory concentration (MIC) was determined for Ff and chloramphenicol. Chromosomal and phylogenetic analyses were performed to investigate the acquisition pattern of the floR gene. The presence of a conserved floR gene in unrelated Acinetobacter spp. isolated from human bacterial infections and environmental samples was observed, suggesting multiple and independent inter-species genetic exchange of drug-resistant determinants. The floR was found to be in the variable region containing various mobile genetic elements and other antibiotic resistance determinants; however, no evidence of HGT could be found. The floR gene identified in this study is chromosomal for all isolates. The study highlights a plausible impact of antimicrobials used in veterinary settings on human health. Ff shares cross-resistance with chloramphenicol, which is still in use in several countries. Furthermore, by selecting for floR-resistance genes, we may be selecting for and facilitating the zoonotic and reverse zoonotic exchange of other flanking resistance markers between human and animal pathogens or commensals with detrimental public health consequences.

Genomic Landscape Reveals Chromosomally-Mediated Antimicrobial Resistome and Virulome of a High-Risk International Clone II Acinetobacter baumannii AB073 from Thailand.

This study utilized integrative bioinformatics' tools together with phenotypic assays to understand the whole-genome features of a carbapenem-resistant international clone II Acinetobacter baumannii AB073. Overall, we found the isolate to be resistant to seven antibiotic classes, penicillins, β-lactam/β-lactamase inhibitor combinations, cephalosporins, carbapenems, aminoglycosides, fluoroquinolones, and folate pathway antagonists. These resistance phenotypes are related to various chromosomal-located antibiotic resistance determinants involved in different mechanisms such as reduced permeability, antibiotic target protection, antibiotic target alteration, antibiotic inactivation, and antibiotic efflux. IC2 A. baumannii AB073 could not transfer antibiotic resistance by conjugation experiments. Likewise, mobilome analysis found that AB073 did not carry genetic determinants involving horizontal gene transfer. Moreover, this isolate also carried multiple genes associated with the ability of iron uptake, biofilm formation, immune invasion, virulence regulations, and serum resistance. In addition, the genomic epidemiological study showed that AB073-like strains were successful pathogens widespread in various geographic locations and clinical sources. In conclusion, the comprehensive analysis demonstrated that AB073 contained multiple genomic determinants which were important characteristics to classify this isolate as a successful international clone II obtained from Thailand.

Exploring the resistome, virulome, and mobilome of multidrug-resistant Klebsiella pneumoniae isolates: deciphering the molecular basis of carbapenem resistance

BackgroundKlebsiella pneumoniae, a notorious pathogen for causing nosocomial infections has become a major cause of neonatal septicemia, leading to high morbidity and mortality worldwide. This opportunistic bacterium has become highly resistant to antibiotics due to the widespread acquisition of genes encoding a variety of enzymes such as extended-spectrum beta-lactamases (ESBLs) and carbapenemases. We collected Klebsiella pneumoniae isolates from a local tertiary care hospital from February 2019–February 2021. To gain molecular insight into the resistome, virulome, and genetic environment of significant genes of multidrug-resistant K. pneumoniae isolates, we performed the short-read whole-genome sequencing of 10 K. pneumoniae isolates recovered from adult patients, neonates, and hospital tap water samples.ResultsThe draft genomes of the isolates varied in size, ranging from 5.48 to 5.96 Mbp suggesting the genome plasticity of this pathogen. Various genes conferring resistance to different classes of antibiotics e.g., aminoglycosides, quinolones, sulfonamides, tetracycline, and trimethoprim were identified in all sequenced isolates. The highest resistance was observed towards carbapenems, which has been putatively linked to the presence of both class B and class D carbapenemases, blaNDM, and blaOXA, respectively. Moreover, the biocide resistance gene qacEdelta1 was found in 6/10 of the sequenced strains. The sequenced isolates exhibited a broad range of sequence types and capsular types. The significant antibiotic resistance genes (ARGs) were bracketed by a variety of mobile genetic elements (MGEs). Various spontaneous mutations in genes other than the acquired antibiotic-resistance genes were observed, which play an indirect role in making these bugs resistant to antibiotics. Loss or deficiency of outer membrane porins, combined with ESBL production, played a significant role in carbapenem resistance in our sequenced isolates. Phylogenetic analysis revealed that the study isolates exhibited evolutionary relationships with strains from China, India, and the USA suggesting a shared evolutionary history and potential dissemination of similar genes amongst the isolates of different origins.ConclusionsThis study provides valuable insight into the presence of multiple mechanisms of carbapenem resistance in K. pneumoniae strains including the acquisition of multiple antibiotic-resistance genes through mobile genetic elements. Identification of rich mobilome yielded insightful information regarding the crucial role of insertion sequences, transposons, and integrons in shaping the genome of bacteria for the transmission of various resistance-associated genes. Multi-drug resistant isolates that had the fewest resistance genes exhibited a significant number of mutations. K. pneumoniae isolate from water source displayed comparable antibiotic resistance determinants to clinical isolates and the highest number of virulence-associated genes suggesting the possible interplay of ARGs amongst bacteria from different sources.

Dissemination, virulence characteristic, antibiotic resistance determinants of emerging linezolid and vancomycin-resistant Enterococcus spp. in fish and crustacean

Enterococci are emerging nosocomial pathogens. Their widespread distribution causes them to be food contaminants. Furthermore, Enterococci can colonize various ecological niches and diffuse into the food chain via contaminated animals and foods because of their remarkable tolerance to unfavorable environmental circumstances. Due to their potential dissemination to humans, antimicrobial-resistant Enterococci in fish are a worldwide health issue. This study characterized AMR, ARGs, VAGs, gelatinase activity, and biofilm formation in Enterococcus spp. recovered from fish and seafood and evaluated potential correlations. 54 Enterococcus spp. strains(32.73 %)were isolated from 165 samples (75 Oreochromis niloticus, 30 Argyrosomus regius, and 60 Shrimp), comprising 30 Enterococcus faecalis (55.6 %) and 24 Enterococcus faecium (44.4 %) with total 32.73 % (54/165), The maximum prevalence rate of Enterococcus spp. was observed in Nile tilapia (34/54; 63 %), followed by shrimp (14/54; 25.9 %) and Argyrosomus regius (6/54; 11.1 %). The maximum prevalence rate of E. faecalis was observed in Nile tilapia (22/30; 73.3 %), followed by shrimp (8/30; 26.7 %) with significant differences. The prevalence rate of E. faecium was observed in Nile tilapia (12/24; 50 %), followed by shrimp (6/24,25 %). E. faecium is only isolated from Argyrosomus regius (6/24,25 %). Isolates exhibited high resistance against both tetracycline (90.7 %) and erythromycin(88.9 %), followed by gentamycin (77.8 %), ciprofloxacin (74.1 %), levofloxacin (72.2 %), penicillin (44.4 %), vancomycin (37 %), and linezolid (20.4 %). 50 strains (92.6 %) exhibited resistance to more than two antibiotics, 5 strains (10 %) were XDR, and the remaining 45 strains (90 %) were classified as MDR. 92.6 % of the isolates had MARindices >0.2, indicating they originated in settings with a high risk of contamination. Additionally, ten ARGs were identified, with tet(M) 92.6 %, followed by erm(B) (88.9 %), aac(6′)-Ie-aph(2″)-Ia(77.8 %), tet(K) (75.9 %), gyrA (74.1 %), blaZ (48.1 %), vanA (37 %), vanB (31.5 %), optrA (20.4 %), and catA(3.7 %). Biofilm formation and gelatinase activity were observed in 85.2 %, and 61.1 % of the isolates, respectively. A total of 11 VAGs were detected, with gelE as the most prevalent (83.3 %) followed by agg(79.6 %), pil (74.1 %), both sprE and asa1 (72.2 %), hyl (70.4 %), eps(68.5 %), EF3314 (57.4 %), ace (50 %), and cylA (35.2 %) with no detection of cylB. In conclusion, the emergence of linezolid-resistant -vancomycin-resistant enterococci recovered from Egyptian fish and shrimp, suggests that fish and seafood might participate a fundamental part in the emergence of antimicrobial resistance among humans.

A Review on Colistin Resistance: An Antibiotic of Last Resort.

Antibiotic resistance has emerged as a significant global public health issue, driven by the rapid adaptation of microorganisms to commonly prescribed antibiotics. Colistin, previously regarded as a last-resort antibiotic for treating infections caused by Gram-negative bacteria, is increasingly becoming resistant due to chromosomal mutations and the acquisition of resistance genes carried by plasmids, particularly the mcr genes. The mobile colistin resistance gene (mcr-1) was first discovered in E. coli from China in 2016. Since that time, studies have reported different variants of mcr genes ranging from mcr-1 to mcr-10, mainly in Enterobacteriaceae from various parts of the world, which is a major concern for public health. The co-presence of colistin-resistant genes with other antibiotic resistance determinants further complicates treatment strategies and underscores the urgent need for enhanced surveillance and antimicrobial stewardship efforts. Therefore, understanding the mechanisms driving colistin resistance and monitoring its global prevalence are essential steps in addressing the growing threat of antimicrobial resistance and preserving the efficacy of existing antibiotics. This review underscores the critical role of colistin as a last-choice antibiotic, elucidates the mechanisms of colistin resistance and the dissemination of resistant genes, explores the global prevalence of mcr genes, and evaluates the current detection methods for colistin-resistant bacteria. The objective is to shed light on these key aspects with strategies for combating the growing threat of resistance to antibiotics.

Antibiotic-Resistance Profiles and Genetic Diversity of Shigella Isolates in China: Implications for Control Strategies.

The urgent need for comprehensive and systematic analyses of Shigella as the key pathogen led us to meticulously explore the epidemiology and molecular attributes of Shigella isolates. Accordingly, we procured 24 isolates (10 from Xinjiang and 14 from Wuhan, China) and performed serotype identification and antimicrobial susceptibility testing. Resistance gene detection and homology analysis by polymerase chain reaction and pulsed-field gel electrophoresis (PFGE), respectively, were performed for genetic diversity analysis. All isolates were identified as Shigella flexneri, with 70% (35.4-91.9%) and 30% (8.1-64.6%) of the Xinjiang isolates and 85.7% (56.2-97.5%) and 14.3% (2/14, 2.5-43.9%) of the Wuhan isolates belonging to serotype 2a and serotype 2b, respectively. All isolates displayed resistance to at least two antibiotics and complete resistance to ampicillin. Multidrug resistance (MDR) was recorded in 70.8% (48.8-86.6%) of isolates, with Xinjiang isolates exhibiting relatively higher resistance to ampicillin-sulbactam, piperacillin, ceftriaxone, and aztreonam. Conversely, Wuhan isolates displayed higher MDR and resistance to tetracycline, ciprofloxacin, levofloxacin, and cefepime relative to Xinjiang isolates. Molecular scrutiny of antibiotic-resistance determinants revealed that blaTEM was the main mechanism of ampicillin resistance, blaCTX-M was the main gene for resistance to third- and fourth-generation cephalosporins, and tetB was the predominant gene associated with tetracycline resistance. Four Xinjiang and seven Wuhan isolates shared T1-clone types (>85%), and two Xinjiang and one Wuhan isolates were derived from the T6 clone with a high similarity of 87%. Six PFGE patterns (T1, T2, T5, T6-3, T8, and T10) of S. flexneri were associated with MDR. Thus, there is a critical need for robust surveillance and control strategies in managing Shigella infections, along with the development of targeted interventions and antimicrobial stewardship programs tailored to the distinct characteristics of Shigella isolates in different regions of China.

Determination of Antagonistic Activity and Antibiotic Resistance of Bacteria and Yeast for Starter Cultures: An Experimental Study to Increase the Production of Fermented Milk Drinks in Kazakhstan

Determination of Antagonistic Activity and Antibiotic Resistance of Bacteria and Yeast for Starter Cultures: An Experimental Study to Increase the Production of Fermented Milk Drinks in Kazakhstan

Unusual and Unconsidered Mechanisms of Bacterial Resilience and Resistance to Quinolones.

Quinolone resistance has been largely related to the presence of specific point mutations in chromosomal targets, with an accessory role of impaired uptake and enhanced pump-out. Meanwhile the relevance of transferable mechanisms of resistance able to protect the target of pump-out or inactivate quinolones has been increasingly reported since 1998. Nevertheless, bacteria have other strategies and mechanisms allowing them to survive and even proliferate in the presence of quinolones, which might be qualified as resistance or resilience mechanisms. These include decreasing levels of quinolone target production, transient amoeba protection, benthonic lifestyle, nutrient-independent slow growth, activation of stringent response, inactivation or degradation of quinolones as well as apparently unrelated or forgotten chromosomal mutations. These mechanisms have been largely overlooked, either because of the use of classical approaches to antibiotic resistance determination or due to the low increase in final minimum inhibitory concentration levels. This article is devoted to a review of a series of these mechanisms.

Characteristics of <i>Streptococcus pneumoniae</i> carriage in the pediatric population

Objective: to investigate the regional peculiarities of Streptococcus pneumoniae carriage in the pediatric population and characterize the dominant serotypes of the pathogen.
 Materials and methods. The clinical study group consisted of 509 healthy children attending preschool institutions. Examination of nasopharyngeal samples for the detection of S. pneumonae was carried out by classical bacteriological and molecular biological methods. The serotype was determined by real-time PCR. Genome-wide sequencing of the serogroups 15 and 11 isolates and bioinformatic analysis were performed.
 Results. The S. pneumoniae bacterial carriers in the group of healthy children was detected in 207 children (40.7%), while the frequency of detection of S. pneumoniae in urban children living in Kazan was significantly higher than in children living in rural area and amounted to 53.4 and 31.1%, respectively (p 0.05). Among children vaccinated with the 13-valent pneumococcal conjugate vaccine (PCV-13), S. pneumoniae carriers were not detected in 57.5% of cases. There were no significant differences in the degree of nasopharyngeal contamination depending on the vaccination status. Analysis of the serotype composition indicates the predominance of vaccine serotypes (57.7%), while the share of serotypes included in the PСV-13 vaccine accounts for only 24.7%, the share of non-vaccine serotypes was 32.1%, untyped — 10.2%. In unvaccinated children, vaccine serotypes that are part of the PCV-13 and 23-valent polysaccharide pneumococcal vaccine prevailed (PPSV-23): 6ABCD (21%), 11 AD (15%), 14 (13%). In vaccinated children, serotypes not included in the active vaccines dominated: 15AF (17.4%), 23A (19.2%), as well as 11AD (19.6%) (11А is included in PPSV-23). The 27 Kz isolate (serotype 15C) belonged to one of the most common sequence types ST1025. The 105_Kz isolate (serotype 11D) belonged to another common sequence type ST 62.
 Conclusion. In order to improve epidemiological surveillance of pneumococcal infection, it is necessary to introduce the monitoring of circulating clonal complexes of dominant S. pneumoniae serogroups and analyze the genetic determinants of antibiotic resistance and virulence depending on the sequence type.

Antibiotic Resistance in Seawater Samples from East Coast of Spain

Seawater has been proposed as a reservoir for antibiotic-resistant bacteria and antibiotic resistance genes, thus representing a risk to public health. In this study, we evaluated the presence of antibiotic resistance determinants (bacteria and genes) in 77 seawater samples collected at different points along the coast of the Gulf of Valencia (Spain). Specifically, indicators of fecal contamination bacteria, Escherichia coli and Enterococcus sp., were isolated, and their antibiotic resistance profiles were analyzed through the use of the Sensititre® system, followed by the detection of the main antibiotic resistance genes (blaTEM, qnrS, tetW, sulI, and ermB). The highest frequencies of resistance in the E. coli isolates were detected for ampicillin (35.1%) and ciprofloxacin (17.5%), followed by sulfamethoxazole and trimethoprim (15.7%), while 23% of enterococci isolates showed resistance to a single antibiotic, 20% against tetracycline and 3% against daptomycin. Through PCR analysis, 93% of the E. coli strains showed the blaTEM and sulI resistance genes. Among the enterococci, the presence of the blaTEM gene was detected in 40% of the isolates, while the rest of the genes were present at very low rates. Among the water samples, 57% were positive for at least one of the tested genes, italic format with blaTEM being the most commonly found gene (47%), followed by the qnrS (33%) and sulI (23%) genes. These results show that seawater, in addition to being subjected to a high rate of fecal contamination, can contribute to the spread of antibiotic resistance.

Biofilms and Antibiotic Resistance Determination from Different Immunocompetent Patients with Salmonellosis

Background: Salmonellosis is an infectious disease due to presence of Salmonella enterica serovars, S. Typhi and S. Typhimurium. Our research demonstrated the antibiotic susceptibility, biofilm formation and isolation of Salmonella from patients. Methods: Biochemical tests and PCR analysis were employed to determine Salmonella isolates (83 isolates out of 217 samples) with the 16S rRNA gene detection. Microtiter plate assay was used to determine the biofilms formation on plastic surfaces. Results: 73.75% Salmonella was isolated from clinical samples. Antibiotic susceptibility showed that 85.18% of isolates from immunocompromised patients were sensitive to levofloxacin, and the rest were resistant to multiple antibiotics. 73.1% of S. Typhi were sensitive to levofloxacin among immunocompetent patients, and 69.23% were resistant to chloramphenicol. PCR test showed a rapid identification of Salmonella serovars. The results demonstrated the biofilm and isolates identification of Salmonella significantly. Increased multidrug resistance were observed from the results. Conclusion: The results showed Salmonella identification, antibiotic resistance, and molecular diagnosis strategy from clinical samples.

Genomic Surveillance Uncovers a 10-Year Persistence of an OXA-24/40 Acinetobacter baumannii Clone in a Tertiary Hospital in Northern Spain.

Infections caused by carbapenem-resistant Acinetobacter baumannii are a global threat causing a high number of fatal infections. This microorganism can also easily acquire antibiotic resistance determinants, making the treatment of infections a big challenge, and has the ability to persist in the hospital environment under a wide range of conditions. The objective of this work was to study the molecular epidemiology and genetic characteristics of two blaOXA24/40Acinetobacter baumannii outbreaks (2009 and 2020-21) at a tertiary hospital in Northern Spain. Thirty-six isolates were investigated and genotypically screened by Whole Genome Sequencing to analyse the resistome and virulome. Isolates were resistant to carbapenems, aminoglycosides and fluoroquinolones. Multi-Locus Sequence Typing analysis identified that Outbreak 1 was mainly produced by isolates belonging to ST3Pas/ST106Oxf (IC3) containing blaOXA24/40, blaOXA71 and blaADC119. Outbreak 2 isolates were exclusively ST2Pas/ST801Oxf (IC2) blaOXA24/40, blaOXA66 and blaADC30, the same genotype seen in two isolates from 2009. Virulome analysis showed that IC2 isolates contained genes for capsular polysaccharide KL32 and lipooligosacharide OCL5. A 8.9 Kb plasmid encoding the blaOXA24/40 gene was common in all isolates. The persistance over time of a virulent IC2 clone highlights the need of active surveillance to control its spread.

Determination of antibiotic resistance in Salmonella Typhimurium and Salmonella Kentucky serotypes of animal origin using conventional and molecular methods

Determination of antibiotic resistance in Salmonella Typhimurium and Salmonella Kentucky serotypes of animal origin using conventional and molecular methods

Volatile organic compounds in headspace characterize isolated bacterial strains independent of growth medium or antibiotic sensitivity.

Early and reliable determination of bacterial strain specificity and antibiotic resistance is critical to improve sepsis treatment. Previous research demonstrated the potential of headspace analysis of volatile organic compounds (VOCs) to differentiate between various microorganisms associated with pulmonary infections in vitro. This study evaluates whether VOC analysis can also discriminate antibiotic sensitive from resistant bacterial strains when cultured on varying growth media. Both antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumonia were cultured on 4 different growth media, i.e. Brain Heart Infusion, Marine Broth, Müller-Hinton and Trypticase Soy Agar. After overnight incubation at 37°C, the headspace air of the cultures was collected on stainless steel desorption tubes and analyzed by gas chromatography time-of-flight mass spectrometry (GC-tof-MS). Statistical analysis was performed using regularized multivariate analysis of variance and cross validation. The three bacterial species could be correctly recognized based on the differential presence of 14 VOCs (p<0.001). This discrimination was not influenced by the different growth media. Interestingly, a clear discrimination could be made between the antibiotic-resistant and -sensitive variant of Pseudomonas aeruginosa (p<0.001) based on their species-specific VOC signature. This study demonstrates that isolated microorganisms, including antibiotic-sensitive and -resistant strains of Pseudomonas aeruginosa, could be identified based on their excreted VOCs independent of the applied growth media. These findings suggest that the discriminating volatiles are associated with the microorganisms themselves rather than with their growth medium. This study exemplifies the potential of VOC analysis as diagnostic tool in medical microbiology. However, validation of our results in appropriate in vivo models is critical to improve translation of breath analysis to clinical applications.