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JAC-antimicrobial Resistance Apr 2024CoNS constitute a significant part of the human microbiota of skin and mucous membranes. They can cause nosocomial infections, and have shown decreased susceptibility to...
BACKGROUND
CoNS constitute a significant part of the human microbiota of skin and mucous membranes. They can cause nosocomial infections, and have shown decreased susceptibility to several antibiotics. The few remaining treatment options include (lipo)glycopeptides such as dalbavancin. However, there is a lack of knowledge concerning whether susceptibility to lipoglycopeptides varies between different species of CoNS.
OBJECTIVES
To determine the susceptibility to dalbavancin in different species of CoNS.
METHODS
We investigated 480 bacterial isolates from 10 CoNS species: , , , , , , , , and . The isolates were randomly selected from different sources of infection, including blood isolates, as well as deep and superficial infections. Antibiotic susceptibility was tested with the gradient test method.
RESULTS
There was a statistically significant difference (ANOVA; < 0.0001) in the MIC distribution for dalbavancin between different CoNS species. was the least susceptible species, with 90% of the isolates having an MIC value for dalbavancin above the EUCAST breakpoint of 0.125 mg/L. The lowest MIC values were seen for , and (all 0.032 mg/L).
CONCLUSIONS
This study demonstrated a difference in dalbavancin susceptibility between different CoNS species, suggesting that species-specific breakpoints for CoNS should be further investigated.
PubMed: 38601789
DOI: 10.1093/jacamr/dlae063 -
Probiotics and Antimicrobial Proteins Apr 2024Pediococcus pentosaceus 732, Lactococcus lactis subsp. lactis 431, and Lactococcus lactis 808, bacteriocinogenic strains previously isolated from kimchi and banana, were...
Safety and Beneficial Properties of Bacteriocinogenic Lactococcus lactis and Pediococcus pentosaceus Strains, and Their Effect Versus Oral Cavity Related and Antibiotic-Resistant Pathogens.
Pediococcus pentosaceus 732, Lactococcus lactis subsp. lactis 431, and Lactococcus lactis 808, bacteriocinogenic strains previously isolated from kimchi and banana, were investigated for their safety, beneficial properties and in vitro inhibition of pathogens such as Listeria monocytogenes ATCC 15313 and Staphylococcus simulans KACC 13241 and Staphylococcus auricularis KACC 13252. The results of performed physiological, biochemical, and biomolecular tests suggest that these strains can be deemed safe, as no virulence genes were detected in their DNA. Notably, only the gad gene associated with GABA production was identified in the DNA isolated of Lc. lactis 808 and Lc. lactis subsp. lactis 431 strains. All tested LAB strains exhibited γ-hemolysins and were non-producers of gelatinase and biogenic amines, which suggested their safety potential. Additionally, they were relatively susceptible to antibiotics except for streptomycin, tobramycin, and vancomycin for Pd. pentosaceus 732. The growth of Pd. pentosaceus 732, Lc. lactis subsp. lactis 431, and Lc. lactis 808 and their survival were minimally affected by up to 3% ox bile and low pH (except pH 2.0 and 4.0). Moreover, these LAB strains were not inhibited by various commercial extracts as well as most of the tested medications tested in the study. They did not produce proteolytic enzymes but exhibited production of D/L-lactic acid and β-galactosidase. They were also hydrophilic. Furthermore, their survival in artificial saliva, gastric simulation, and enteric passage was measured followed by a challenge test to assess their ability to inhibit the selected oral pathogens in an oral saliva model conditions.
PubMed: 38564170
DOI: 10.1007/s12602-024-10245-z -
Food Chemistry: X Mar 2024The aim of this study was to investigate and compare the effects of different mixed starter cultures ( and ) on the bacterial communities and flavor of fermented...
The aim of this study was to investigate and compare the effects of different mixed starter cultures ( and ) on the bacterial communities and flavor of fermented sausages. The results indicated that native starters grew well in fermented sausages and became dominant at the end of ripening. Among them, spp. had the highest relative abundance, followed by spp. In addition, the inoculation of the mixed starters promoted the formation of taste and aroma compounds that contribute to the overall flavor of the fermented sausages. Among them, the CQ01107 + CD207 (CCA) treatment was found to have the highest umami amino acid, nucleotide, lactic acid, fatty acid and ketone contents ( < 0.05), as well as excellent sensory properties. In conclusion, the CCA starter may be a desirable starter culture to enhance the flavor of fermented sausages.
PubMed: 38389578
DOI: 10.1016/j.fochx.2024.101225 -
Veterinary World Dec 2023The agar dilution method is the approved method for determining the minimum inhibitory concentration (MIC) in fosfomycin susceptibility testing, whereas the broth...
BACKGROUND AND AIM
The agar dilution method is the approved method for determining the minimum inhibitory concentration (MIC) in fosfomycin susceptibility testing, whereas the broth dilution method is not recommended. This study aimed to investigate the potential of the gradient diffusion method as a more convenient alternative to agar dilution method for MIC evaluation, particularly for the susceptibility testing of spp. and spp. to fosfomycin.
MATERIALS AND METHODS
A total of 194 isolates of spp. and spp. were collected from urine samples of dogs diagnosed with bacterial cystitis. Bacterial identification and susceptibility to multiple antibiotics were tested using the Vitek 2 automated system. The susceptibility to fosfomycin was compared between agar dilution (reference method) and the gradient diffusion method. We assessed the agreement rates and errors between the two approaches by analyzing the MIC data.
RESULTS
(98.7%) and (80.0%) exhibited high fosfomycin susceptibility rates, whereas exhibited a lower susceptibility rate (38.5%). The gradient diffusion method demonstrated unacceptably low essential agreement (EA) rates (>90%) but acceptable categorical agreement (CA) rates (≥ 90%) for (83.54% EA and 97.47% CA) and coagulase-negative staphylococci (CoNS) such as , , and (85.00% EA and 95.00% CA). spp. had an acceptable EA of 93.75%, but an unacceptably low CA rate of 82.81%, with a minor error rate of 17.19%. No significant errors were observed for and spp.
CONCLUSION
The gradient diffusion method reliably determines MICs and interpretative breakpoints (S, I, R) for . However, its applicability to CoNS and enterococci may be limited due to unacceptable errors.
PubMed: 38328370
DOI: 10.14202/vetworld.2023.2497-2503 -
Food Chemistry Jun 2024The purpose of this study was to reveal the effect of inoculating autochthonous bacterial strains (Lactobacillus and Staphylococcus simulans) on the flavor profiles,...
Insight into the autochthonous bacterial strains as starter cultures for improving the flavor profiles of dry-cured duck: Changes in microbial diversity and metabolic profiles.
The purpose of this study was to reveal the effect of inoculating autochthonous bacterial strains (Lactobacillus and Staphylococcus simulans) on the flavor profiles, microbial community, and metabolites, and to elucidate the potential mechanism of flavor formation in dry-cured duck. The results indicated that the inoculation of bacterial strains could improve the amount of lactic acid bacteria and Staphylococcus and reduce the counts of Enterobacteria. There was a significant difference in flavor profiles between samples inoculated with different strains. Hexanal-D, acetone, 3-methyl-1-butanol-D, thiophene, hexanal-M, propanal, pentanal, (Z)-2-penten-1-ol and ethanol-D were the potential biomarkers. A total of 70 differential metabolites were screened and identified. Amino acid metabolism and lipid metabolism were the key pathways for the production of flavor and metabolites in dry-cured duck. The results of this study will improve our understanding of the mechanism of flavor formation regarding the inoculation of autochthonous starter cultures.
Topics: Animals; Ducks; Food Microbiology; Fermentation; Bacteria; Metabolome; Aldehydes
PubMed: 38281415
DOI: 10.1016/j.foodchem.2024.138446 -
Biochimica Et Biophysica Acta.... Mar 2024Epilancin 15X is a lantibiotic that has an antimicrobial activity in the nanomolar concentration range towards Staphylococcus simulans. Such low MICs usually imply that... (Review)
Review
Epilancin 15X is a lantibiotic that has an antimicrobial activity in the nanomolar concentration range towards Staphylococcus simulans. Such low MICs usually imply that these peptides employ a mechanism of action (MoA) involving high affinity targets. Here we studied this MoA by using epilancin 15X's ability to dissipate the membrane potential of intact S. simulans cells. These membrane depolarization assays showed that treatment of the bacteria by antibiotics known to affect the bacterial cell wall synthesis pathway decreased the membrane depolarization effects of epilancin 15X. Disruption of the Lipid II cycle in intact bacteria using several methods led to a decrease in the activity of epilancin 15X. Antagonism-based experiments on 96-well plate and agar diffusion plate pointed towards a possible interaction between epilancin 15X and Lipid II and this was confirmed by Circular Dichroism (CD) based experiments. However, this interaction did not lead to a detectable effect on either carboxyfluorescein (CF) leakage or proton permeability. All experiments point to the involvement of a phosphodiester-containing target within a polyisoprene-based biosynthesis pathway, yet the exact identity of the target remains obscure so far.
Topics: Amino Acid Sequence; Bacteriocins; Anti-Bacterial Agents; Peptides
PubMed: 38218577
DOI: 10.1016/j.bbamem.2024.184282 -
Journal of Dairy Science Jun 2024Non-aureus staphylococci and mammaliicocci (NASM) are the most frequently isolated bacterial group from bovine milk samples. Most studies focus on subclinical mastitis...
Non-aureus staphylococci and mammaliicocci (NASM) are the most frequently isolated bacterial group from bovine milk samples. Most studies focus on subclinical mastitis caused by NASM; however, NASM can cause clinical mastitis (CM) as well. We evaluated retrospective data from 6 years (2017-2022) to determine the species and frequency of NASM isolated from quarter bovine CM. The data was comprised of microbiological results from quarter CM samples routinely submitted to Quality Milk Production Services at Cornell University for microbial identification by MALDI-TOF mass spectrometry. A total of 9,909 microbiological results from 410 dairy herds were evaluated. Our results showed that 29 distinct NASM species were identified, with the 8 most prevalent NASM species being Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus simulans, Staphylococcus epidermidis, Staphylococcus sciuri (now Mammaliicoccus sciuri), Staphylococcus agnetis/Staphylococcus hyicus, Staphylococcus borealis, and Staphylococcus xylosus. The NASM distribution remained similar among seasons, but the frequency of NASM CM cases was higher during the summer. Our results showed different patterns of variations in the isolation frequency over time, depending on the bacterial species: increasing or decreasing trends, cyclic fluctuations, and, except for Staphylococcus borealis, a significant seasonality effect for our study's most prevalent NASM. This study showed that Staphylococcus chromogenes remains the most frequent (43%) NASM species identified from bovine CM, followed by Staphylococcus haemolyticus (18%), and Staphylococcus simulans (12%).
Topics: Animals; Cattle; Mastitis, Bovine; Female; Retrospective Studies; Staphylococcus; Milk; Staphylococcal Infections
PubMed: 38056569
DOI: 10.3168/jds.2023-24086 -
Journal of Dairy Science May 2024There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the... (Observational Study)
Observational Study
There are limited data available regarding pathogens causing intramammary infections (IMI) in Jersey cows. The objectives of this study were to characterize the prevalence of IMI caused by different microorganisms in lactating Jersey cattle and evaluate the associations among microbes and somatic cell count (SCC) and persistence of IMI. This prospective, observational, longitudinal study included lactating Jersey cows (n = 753) from 4 farms within a 415 km radius of Columbia, Missouri. Quarter foremilk samples were aseptically collected monthly for 3 consecutive months. Microorganisms were identified using aerobic milk culture and MALDI-TOF mass spectrometry. A commercial laboratory measured SCC using flow cytometry. Milk culture results were used to classify single microorganism infections as persistent (same microorganism species identified at first sampling and one other sampling) or nonpersistent infection. Mixed models were built to evaluate the associations between IMI status and SCC natural logarithm (lnSCC), as well as persistence and lnSCC. Overall, staphylococci were the most commonly isolated microorganisms among the 7,370 quarter-level milk samples collected. Median prevalence (using all 3 samplings) of specific microbes varied among farms; however, Staphylococcus chromogenes was a common species found at all farms. The most common microbial species that persisted were Staph. chromogenes, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus uberis. Streptococcus dysgalactiae and Staph. aureus were the IMI associated with the most inflammation based on lnSCC. The small number of herds included in this study with the large variation in herd type limits the generalizability of the data. However, results of this study seem to be similar to those of previous studies in other breeds, suggesting management factors are more important than breed-specific differences when evaluating causes of IMI and associated subclinical mastitis.
Topics: Cattle; Animals; Female; Milk; Lactation; Prevalence; Longitudinal Studies; Prospective Studies; Mastitis, Bovine; Staphylococcal Infections; Staphylococcus aureus; Cell Count; Cattle Diseases
PubMed: 37949401
DOI: 10.3168/jds.2023-23848 -
Journal of Dairy Science Nov 2023Staphylococcus chromogenes and Staphylococcus simulans are commonly found in intramammary infections (IMI) associated with bovine subclinical mastitis, but little is...
Staphylococcus chromogenes and Staphylococcus simulans are commonly found in intramammary infections (IMI) associated with bovine subclinical mastitis, but little is known about genotypic variation and relatedness within species. This includes knowledge about genes encoding antimicrobial resistance (AMR) and potential virulence factors (pVF). The aim of this study was therefore to investigate these aspects by whole-genome sequencing of milk isolates from Swedish dairy cows with subclinical mastitis in an observational study. We also wanted to study if specific genotypes were associated with persistent IMI and the inflammatory response at udder quarter level. In total, 105 and 118 isolates of S. chromogenes and S. simulans, respectively, were included. Isolates were characterized using a 7-locus multilocus sequence typing (7-MLST), core genome analysis and in-silico analysis of AMR and pVF genes. Forty-seven sequence types (ST) and 7 core genome clusters of S. chromogenes were identified, and the most common ST were ST-6 and ST-109, both belonging to cluster VII. A 7-locus MLST scheme for S. simulans was not available, but 3 core genome clusters and 5 subclusters were described. Overall, substantial variation in ST and clusters among cows and herds were found in both species. Some ST of S. chromogenes were found in several herds, indicating spread between herds. Moreover, within-herd spread of the same genotype was observed for both species. Only a few AMR genes [blaZ, strpS194, vga(A)] were detected in a limited number of isolates, with the exception of blaZ coding for β-lactamase, which was identified in 22% of the isolates of S. chromogenes with ST-19, ST-102, and ST-103 more commonly carrying this gene compared with other ST. However, the blaZ gene was not identified in S. simulans. The average total number of pVF detected per isolate was similar in S. chromogenes (n = 30) and S. simulans (n = 33), but some variation in total numbers and presence of specific pVF or functional groups of pVF, was shown between ST/clusters within species. Differences in inflammatory response and potentially in persistent IMI at udder quarter level were found between S. chromogenes subtypes but not between S. simulans subtypes. In conclusion, the results from the present study generates new insight into the epidemiology of bovine S. chromogenes and S. simulans IMI, which can have implications for future prevention and antimicrobial treatment of infections related to these species.
PubMed: 37641317
DOI: 10.3168/jds.2023-23523 -
Probiotics and Antimicrobial Proteins Aug 2023Bacteriocins are antimicrobial peptides produced by bacteria. This study aimed to in silico analyze the presence of bacteriocin gene clusters (BGCs) among the genomes of...
Bacteriocins are antimicrobial peptides produced by bacteria. This study aimed to in silico analyze the presence of bacteriocin gene clusters (BGCs) among the genomes of 22 commensal Staphylococcus isolates from different origins (environment/human/food/pet/wild animals) previously identified as bacteriocin producers. The resistome and plasmidome were studied in all isolates. Five types of BGC were detected in 18 genomes of the 22 bacteriocin-producing staphylococci included in this study: class I (Lanthipeptides), class II, circular bacteriocins, the non-ribosomal-peptide lugdunin and the thiopeptide micrococcin P1 (MP1). A high frequency of lanthipeptides was detected in this collection: BGC variants of BSA, bacCH91, and epilancin15X were identified in two Staphylococcus aureus and one Staphylococcus warneri isolates from food and wild animals. Moreover, two potentially new lanthipeptide-like BGCs with no identity to database entries were found in Staphylococcus epidermidis and Staphylococcus simulans from food and wild animal, respectively. Interestingly, four isolates (one S. aureus and one Staphylococcus hominis, environmental origin; two Staphylococcus sciuri, food) carried the MP1 BGC with differences to those previously described. On the other hand, seven of the 22 genomes (~32%) lacked known genes related with antibiotic or disinfectant-acquired resistance mechanisms. Moreover, the potential carriage of plasmids was evaluated, and several Rep-proteins were identified (~73% of strains). In conclusion, a wide variety of BGCs has been observed among the 22 genomes, and an interesting relationship between related Staphylococcus species and the type of bacteriocin has been revealed. Therefore, bacteriocin-producing Staphylococcus and especially coagulase-negative staphylococci (CoNS) can be considered good candidates as a source of novel bacteriocins.
PubMed: 37632676
DOI: 10.1007/s12602-023-10119-w