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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 -
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 Microbiology and... Jun 2023Microbial biofilms are resilient, immune-evasive, often antibiotic-resistant health challenges, and increasingly the target for research into novel therapeutic...
Microbial biofilms are resilient, immune-evasive, often antibiotic-resistant health challenges, and increasingly the target for research into novel therapeutic strategies. We evaluated the effects of a nutraceutical enzyme and botanical blend (NEBB) on established biofilm. Five microbial strains with known implications in chronic human illnesses were tested: , and . The strains were allowed to form biofilm in vitro. Biofilm cultures were treated with NEBB containing enzymes targeted at lipids, proteins, and sugars, also containing the mucolytic compound N-acetyl cysteine, along with antimicrobial extracts from cranberry, berberine, rosemary, and peppermint. The post-treatment biofilm mass was evaluated by crystal-violet staining, and metabolic activity was measured using the MTT assay. Average biofilm mass and metabolic activity for NEBB-treated biofilms were compared to the average of untreated control cultures. Treatment of established biofilm with NEBB resulted in biofilm-disruption, involving significant reductions in biofilm mass and metabolic activity for and both species. For , we observed reduced biofilm mass, but the remaining residual biofilm showed a mild increase in metabolic activity, suggesting a shift from metabolically quiescent, treatment-resistant persister forms of to a more active form, potentially more recognizable by the host immune system. For , low doses of NEBB significantly reduced biofilm mass and metabolic activity while higher doses of NEBB increased biofilm mass and metabolic activity. The results suggest that targeted nutraceutical support may help disrupt biofilm communities, offering new facets for integrative combinational treatment strategies.
Topics: Humans; Anti-Bacterial Agents; Staphylococcus aureus; Anti-Infective Agents; Staphylococcal Infections; Biofilms; Pseudomonas aeruginosa; Microbial Sensitivity Tests
PubMed: 37072676
DOI: 10.4014/jmb.2212.12010 -
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 -
Journal of Dairy Science Nov 2023Subclinical mastitis can be common among freshly calved heifers (FCH), but the prevalence differs between herds, possibly due to variation in risk factors. The aims of...
Subclinical mastitis can be common among freshly calved heifers (FCH), but the prevalence differs between herds, possibly due to variation in risk factors. The aims of this observational study were to identify differences in occurrence of intramammary infection (IMI) in FCH between herds with documented good or poorer first-parity udder health based on cow somatic cell count (CSCC) in early lactation, and to study herd differences in animal factors important for udder health, such as udder and hock skin lesions and animal cleanliness. Three groups of herds were included: those with high proportions of FCH with low CSCC (≤75,000 cells/mL) at the first 2 milk recordings after calving (LL), herds with high proportions of FCH with high CSCC (>100,000 cells/mL) at the first and low CSCC at the second recording (HL), and herds with high proportions of FCH with high CSCC at both recordings (HH). Thirty-nine herds (13 LL, 11 HL, 15 HH) were visited 3 times during a 12-mo period for observation of cleanliness and hock lesions, and sampling of udder and teat skin using swab cloths of milk-fed calves, early-pregnant heifers, and late-pregnant heifers. In 25 (9 LL, 9 HL, 7 HH) udder quarter samples from colostrum and milk on d 3 to 4 after calving were taken by the farmers from FCH during one year. The farmers also provided information on calving (individual or group), use of restraint and oxytocin at milking, and presence of teat and udder skin lesions. Bacterial growth in swab samples and quarter samples was investigated by culturing, and a selection of isolates was genotyped using whole-genome sequencing. Cleanliness, hock and udder skin lesions other than udder-thigh dermatitis, and growth of bacteria in swab samples did not differ between herd groups. It was more common that FCH from LL herds, compared with FCH in HH and HL herds, calved in a group of animals. Use of restraint at milking was more common in LL herds than in HH herds, whereas presence of udder-thigh dermatitis was lowest in LL herds. Specific infection was found in 14% of 5,593 quarter samples from 722 FCH. The most common IMI was Staphylococcus chromogenes. Growth of Staphylococcus simulans was more common in HH than in LL and HL herds. In colostrum samples, Staphylococcus haemolyticus was more common in HL and HH than in LL herds. The proportion of quarters with the same specific infection at both samplings was higher in HH than in LL herds and tended to be higher in HH than in HL herds. The proportion of quarters with Staph. chromogenes IMI at both samplings tended to differ between herd groups and was highest in HH herds. Whole-genome sequencing found the same sequence type of Staph. chromogenes and Staphylococcus aureus in both samples in almost all quarters with the same infection at both samplings. The differences in IMI between herd groups were in line with the higher somatic cell count in HH herds. The reasons for the predominance of Staph. chromogenes IMI in FCH need further studies.
PubMed: 37210369
DOI: 10.3168/jds.2022-22995 -
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 -
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 -
Biochimica Et Biophysica Acta.... Aug 2023Antimicrobial peptides (AMPs) commonly target bacterial membranes and show broad-spectrum activity against microorganisms. In this research we used three AMPs (nisin,...
Antimicrobial peptides (AMPs) commonly target bacterial membranes and show broad-spectrum activity against microorganisms. In this research we used three AMPs (nisin, epilancin 15×, [R4L10]-teixobactin) and tested their membrane effects towards three strains (Staphylococcus simulans, Micrococcus flavus, Bacillus megaterium) in relation with their antibacterial activity. We describe fluorescence and luminescence-based assays to measure effects on membrane potential, intracellular pH, membrane permeabilization and intracellular ATP levels. The results show that our control peptide, nisin, performed mostly as expected in view of its targeted pore-forming activity, with fast killing kinetics that coincided with severe membrane permeabilization in all three strains. However, the mechanisms of action of both Epilancin 15× as well as [R4L10]-teixobactin appeared to depend strongly on the bacterium tested. In certain specific combinations of assay, peptide and bacterium, deviations from the general picture were observed. This was even the case for nisin, indicating the importance of using multiple assays and bacteria for mode of action studies to be able to draw proper conclusions on the mode of action of AMPs.
Topics: Nisin; Antimicrobial Peptides; Antimicrobial Cationic Peptides; Bacteria; Anti-Bacterial Agents
PubMed: 37100361
DOI: 10.1016/j.bbamem.2023.184160 -
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 -
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