The Genus Macrococcus: An Insight Into Its Biology, Evolution, and Relationship With Staphylococcus

Interaction and cross-contamination potential of prepared beef steak isolates Pseudomonas weihenstephanensis and Macrococcus caseolyticus in biofilms of dual-species

This study evaluated the interactions between single or dual-species biofilms formed by dominant spoilage bacteria P. weihenstephanensis and M. caseolyticus isolated from refrigerated, spoilage prepared beef steaks at 4 °C and elucidated the interactive behavior of biofilm development in dual species. In addition, the relationship between biofilm formation capacity and cross-contamination was analyzed by simulating surface to food contact transfer. The results showed that the two species exhibited synergism as biofilms developed, which was the main mode of interaction observed. Under aerobic conditions, Pseudomonas weihenstephanensis and Macrococcus caseolyticus co-cultured for 96 h showed obvious biofilm formation ability, resulting in greater cross-contamination. Scanning electron microscopy and Confocal laser scanning microscopy showed the formation of flattened dense biofilms in the co-culture. The significant increase in Fe content and decrease in siderophore content of the dual-species biofilm as determined by ICP-MS was attributed to respiratory inhibition resulting in a decrease in the transcription of genes regulating the two-component regulatory system of Macrococcus tyrolyticus SrrAB and an increase in the expression of cytoplasmic hydrolase leading to the rupture of the release of hemoglobin to provide a source of iron for P. weihenstephanensis. The increase of heme content in the supernatant of dual-species and the results of RT-qPCR showed that the gene expression of the heme transport system of P. weihenstephanensis was significantly up-regulated and the siderophore gene expression was decreased, which further revealed that P. weihenstephanensis preferentially uses the heme uptake system to take up the iron source provided by M. caseolyticus for P. weihenstephanensis. Overall, our results provide insight into the complex dynamics of biofilms formed by P. weihenstephanensis and M. caseolyticus, emphasizing that the iron reaction pathway may be a key factor influencing the growth of P. weihenstephanensis biofilms, and that these results will provide a theoretical basis for the control of spoilage of refrigerated foods.

Unveiling microbial dynamics in terasi spontaneous fermentation: Insights into glutamate and GABA production

Terasi, a traditional Indonesian seafood product made from shrimp, undergoes fermentation facilitated by a consortium of microorganisms, including Lactic Acid Bacteria (LAB) and yeast, which contribute to its distinctive umami flavor. This study investigates the microbial dynamics and production of key metabolites, including γ-aminobutyric acid (GABA), during terasi fermentation. Total Plate Count (TPC) and High-Performance Liquid Chromatography (HPLC) were used to monitor changes in glutamate and GABA levels, with glutamate increasing from 105.18 mg/mL on day 3-139.19 mg/mL on day 14, and GABA rising from 90.49 mg/mL to 106.98 mg/mL over the same period. Metagenomic analysis using high-throughput sequencing of bacterial 16 S rRNA identified Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidota as dominant phyla. While LAB populations remained relatively stable, yeast became detectable from day 4. Notably, core bacterial genera such as Vibrio, Macrococcus, Staphylococcus, Exiguobacterium, Jeotgalicoccus, Prevotella, Salinicoccus, Bacillus, Pseudarthrobacter, and Vagococcus were highly abundant and played significant roles in GABA production, likely due to their glutamate decarboxylase activity. These findings reveal a clear correlation between microbial succession and metabolite production, offering valuable insights into the fermentation process of terasi. This study enhances the understanding of traditional food fermentation and presents opportunities to optimize beneficial compounds in terasi products.

Microbial Diversity and Community Structure of Chinese Fresh Beef during Cold Storage and Their Correlations with Off-Flavors

To investigate the diversity and dynamics of microorganisms in Chinese fresh beef (CFB) without acid discharge treatment during cold storage, high-throughput sequencing was employed to analyze the CFB refrigerated for 0, 3, 7, and 10 days. The results showed that the community richness of the fungi and bacteria decreased significantly. However, the diversity decreased in the early stage and increased in the later stage. At the phylum level, Ascomycota (74.1-94.1%) and Firmicutes (77.3-96.8%) were the absolutely dominant fungal and bacterial phyla. The relative abundance of both fungal and bacterial phyla displayed a trend of increasing and then decreasing. At the genus level, Candida (29.3-52.5%) and Lactococcus (19.8-59.3%) were, respectively, the dominant fungal and bacterial genera. The relative abundance of Candida showed a trend of increasing and then decreasing, while Lactococcus possessed the opposite trend. KEGG metabolic pathways analysis suggested that carbohydrate metabolism, membrane transport, and amino acid metabolism were the major metabolic pathways of bacteria. Bugbase prediction indicated the major microbial phenotype of bacteria in CFB during cold storage was Gram-positive (17.2-31.6%). Correlation analysis suggested that Lactococcus, Citrobacter, Proteus, and Rhodotorula might be the main microorganisms promoting the production of off-flavor substances in CFB. This study provides a theoretical basis for the preservation of Chinese fresh beef.

Screening and evaluating microorganisms with broad-spectrum biogenic amine-degrading ability from naturally fermented dry sausage collected from Northeast China

This study aimed to screen autochthonous strains with broad-spectrum biogenic amine (BA) degradation ability from traditional dry sausages and to evaluate their BA-degrading ability in dry sausages. A total of 120 strains were isolated from dry sausages collected from various regions in Northeast China, and 35 of 120 isolates were identified as non-BA producing strains by the in vitro agar method. The random amplified polymorphic DNA polymerase chain reaction technique genotyped these 35 isolates into 18 biotypes. Moreover, high performance liquid chromatography (HPLC) quantification showed that six strains (Latilactobacillus sakei MDJ6; Lactiplantibacillus plantarum SH7; Weissella hellenica DQ9; Staphylococcus saprophyticus JX18 and SYS8; and Macrococcus caseolyticus SYS11) of the 18 biotypes exhibited broad-spectrum BA-degrading ability, all of which had various levels of amine oxidase activity with monoamine oxidase and diamine oxidase activities ranged of 6.60-619.04 and 26.32-352.81 U/mg protein, respectively. These six strains were subsequently inoculated into dry sausages and the results showed that they exhibited varying degrees of BA-degrading ability, of which strain Lat. sakei MDJ6 allowed to have less BA production on dry sausage with a final concentration of 61.33 mg/kg.

The host sex contributes to the endophytic bacterial community in Sargassum thunbergii and their receptacles

Endophytic bacteria have a complex coevolutionary relationship with their host macroalgae. Dioecious macroalgae are important producers in marine ecosystems, but there is still a lack of research on how sex influences their endophytic bacteria. In this study, the endophytic bacterial communities in male and female S. thunbergii and their reproductive tissues (receptacles) were compared using culture methods and high-throughput sequencing. The endophytic bacterial communities detected by the two methods were different. Among the 78 isolated strains, the dominant phylum, genus, and species were Bacillota, Alkalihalobacillus, and Alkalihalobacillus algicola, respectively, in the algal bodies, while in the receptacles, they were Bacillota, Vibrio, and Vibrio alginolyticus. However, 24 phyla and 349 genera of endophytic bacteria were identified by high-throughput sequencing, and the dominant phylum and genus were Pseudomonadota and Sva0996_ Marine_ Group, respectively, in both the algal body and the receptacles. The two methods showed similar compositions of endophytic bacterial communities between the samples of different sexes, but the relative abundances of dominant and specific taxa were different. The high-throughput sequencing results showed more clearly that the sex of the host alga had an effect on its endophyte community assembly and a greater effect on the endophytic bacterial community in the receptacles. Moreover, most specific bacteria and predicted functional genes that differed between the samples from the males and females were related to metabolism, suggesting that metabolic differences are the main causes of sex differences in the endophytic bacterial community. Our research is the first to show that host sex contributes to the composition of endophytic bacterial communities in dioecious marine macroalgae. The results enrich the database of endophytic bacteria of dioecious marine macroalgae and pave the way for better understanding the assembly mechanism of the endophytic bacterial community of algae.

Genus-wide genomic characterization of Macrococcus: insights into evolution, population structure, and functional potential

Introduction

Macrococcus species have been isolated from a range of mammals and mammal-derived food products. While they are largely considered to be animal commensals, Macrococcus spp. can be opportunistic pathogens in both veterinary and human clinical settings. This study aimed to provide insight into the evolution, population structure, and functional potential of the Macrococcus genus, with an emphasis on antimicrobial resistance (AMR) and virulence potential.

Methods

All high-quality, publicly available Macrococcus genomes (n = 104, accessed 27 August 2022), plus six South African genomes sequenced here (two strains from bovine clinical mastitis cases and four strains from beef products), underwent taxonomic assignment (using four different approaches), AMR determinant detection (via AMRFinderPlus), and virulence factor detection (using DIAMOND and the core Virulence Factor Database).

Results

Overall, the 110 Macrococcus genomes were of animal commensal, veterinary clinical, food-associated (including food spoilage), and environmental origins; five genomes (4.5%) originated from human clinical cases. Notably, none of the taxonomic assignment methods produced identical results, highlighting the potential for Macrococcus species misidentifications. The most common predicted antimicrobial classes associated with AMR determinants identified across Macrococcus included macrolides, beta-lactams, and aminoglycosides (n = 81, 61, and 44 of 110 genomes; 73.6, 55.5, and 40.0%, respectively). Genes showing homology to Staphylococcus aureus exoenzyme aureolysin were detected across multiple species (using 90% coverage, n = 40 and 77 genomes harboring aureolysin-like genes at 60 and 40% amino acid [AA] identity, respectively). S. aureus Panton-Valentine leucocidin toxin-associated lukF-PV and lukS-PV homologs were identified in eight M. canis genomes (≥40% AA identity, >85% coverage). Using a method that delineates populations using recent gene flow (PopCOGenT), two species (M. caseolyticus and M. armenti) were composed of multiple within-species populations. Notably, M. armenti was partitioned into two populations, which differed in functional potential (e.g., one harbored beta-lactamase family, type II toxin-antitoxin system, and stress response proteins, while the other possessed a Type VII secretion system; PopCOGenT p < 0.05).

Discussion

Overall, this study leverages all publicly available Macrococcus genomes in addition to newly sequenced genomes from South Africa to identify genomic elements associated with AMR or virulence potential, which can be queried in future experiments.

Microbiological Quality and Safety of Fresh Turkey Meat at Retail Level, Including the Presence of ESBL-Producing Enterobacteriaceae and Methicillin-Resistant S. aureus

The aim of this work was to study the microbiological safety and quality of marketed fresh turkey meat, with special emphasis on methicillin-resistant S. aureus, ESBL-producing E. coli, and K. pneumoniae. A total of 51 fresh turkey meat samples were collected at retail level in Spain. Mesophile, Pseudomonas spp., enterococci, Enterobacteriaceae, and staphylococci counts were 5.10 ± 1.36, 3.17 ± 0.87, 2.03 ± 0.58, 3.18 ± 1.00, and 2.52 ± 0.96 log CFU/g, respectively. Neither Campylobacter spp. nor Clostridium perfringens was detected in any sample. ESBL-producing K. pneumoniae and E. coli were detected in 22 (43.14%), and three (5.88%) samples, respectively, all of which were multi-resistant. Resistance to antimicrobials of category A (monobactams, and glycilcyclines) and category B (cephalosporins of third or fourth generation, polymixins, and quinolones), according to the European Medicine Agency classification, was found among the Enterobacteriaceae isolates. S. aureus and methicillin-resistant S. aureus were detected in nine (17.65%) and four samples (7.84%), respectively. Resistance to antimicrobials of category A (mupirocin, linezolid, rifampicin, and vancomycin) and category B (cephalosporins of third- or fourth generation) was found among S. aureus, coagulase-negative staphylococci, and M. caseolyticus isolates.

The emergence of novel macrolide resistance island in Macrococcus caseolyticus and Staphylococcus aureus of food origin

Food-derived Staphylococcaceae species with severe antimicrobial resistance, especially Staphylococcus aureus, is a major threat to public health. Macrococcus caseolyticus (M. caseolyticus) is a member of the Staphylococcaceae family which plays a vital role in fermented products and disease causation in animals. In our previous study, several Staphylococcus aureus antibiotic-resistant island msr (SaRI_msr) were found in multidrug-resistant S. aureus. In this study, novel SaRI_msr, SaRI_msr-III emerged from S. aureus. Another novel SaRI_msr-like further emerged in M. caseolyticus from food. These isolates' prevalence and genetic environment were investigated and characterized to understand the distribution and transmission of these novel SaRI_msr strains. All SaRI_msr-positive S. aureus isolates exhibited a multidrug resistance (MDR) phenotype, within which a series of antimicrobial resistance genes (ARGs) and virulence factor genes (VFs) were identified. In addition, three SaRI_msr types, SaRI_msr-I (15.1 kb), SaRI_msr-II (16-17 kb), and SaRI_msr-III (18 kb) carrying mef(D)-msr(F), were identified in these isolates' chromosomes. SaRI_msr-(I-III) contains a site-specific integrase gene int and operon mef(D)-msr(F). SaRI_msr-III has an additional orf3-orf4-IS30 arrangement downstream of mef(D) and msr(F). Moreover, the SaRI_msr-like and macrolide-resistant transposon Tn6776 forming a novel mosaic structure coexisted in one M. caseolyticus isolate. Within this mosaic structure, the macrolide-resistant genes mef(D)-msr(F) were absent in SaRI_msr-like, whereas an operon, mef(F)-msr(G), was identified in Tn6776. The SaRI_msr-(I-III) and SaRI_msr-like structure were inserted into the rpsI gene encoding the 30S ribosomal protein S9 in the chromosome. Excision and cyclisation of SaRI_msr-III, SaRI_msr-like, operon mef(D)-msr(F), and orf3-orf4-IS30 arrangements were confirmed using two-step PCR. This study is the first to report MDR S. aureus harbouring novel SaRI_msr-III and M. caseolyticus containing novel mosaic structures isolated from retail foods. Similar SaRI_msr-type resistant islands' occurrence and propagation in Staphylococcaceae species require continuous monitoring and investigation.

Effect of the Presence of Antibiotic Residues on the Microbiological Quality and Antimicrobial Resistance in Fresh Goat Meat

A total of 11 fresh goat legs were collected at the retail level. Mesophiles, Pseudomonas spp., Enterobacteriaceae, staphylococci, enterococci, Clostridium perfringens, Campylobacter spp., and Listeria monocytogenes counts were determined. Nine samples were free of antibiotic residues, while in the other two samples the presence of sulfadiazine and doxycycline was detected. The antimicrobial resistance of E. coli, staphylococci, Macrococcus spp., and enterococci isolates was also evaluated. Clostridium perfringens was found in two samples. Methicillin-resistant Staphylococcus aureus was detected in one sample. S. epidermidis isolated from one sample containing doxycycline residues showed resistance to mupirocin. Moreover, multi-resistant S. epidermidis and M. caseolyticus were found. Most of the isolated Enterococcus faecium were multi-resistant. Neither extended-spectrum β-lactamase -producing E. coli nor vancomycin-resistant enterococci were detected in any sample. The presence of doxycycline or sulfadiazine could affect the goat meat microbiota since less microbial diversity was found in these samples compared to those free of antibiotics. The presence of antibiotic residues could increase the antimicrobial resistance of enterococci in fresh goat meat. The presence of multidrug-resistant bacteria in goat meat could be considered a potential threat and should be monitored. Special measures should be taken at the farm level and during slaughter to reduce antimicrobial resistance.

Macrococcus armenti sp. nov., a novel bacterium isolated from the skin and nasal cavities of healthy pigs and calves

Gram-positive coccoid bacteria were isolated from the nasal cavities of pigs and calves as well as from axillar and inguinal skin regions of pigs. Phylogenetic analysis of seven strains based on complete genome, 16S rRNA, hsp60, dnaJ, rpoB and sodA gene sequences and MALDI-TOF MS profiles revealed that they belonged to the genus Macrococcus with the closest relatedness to Macrococcus canis , Macrococcus caseolyticus subsp. caseolyticus and Macrococcus caseolyticus subsp. hominis . DNA relatedness of the type strain JEK37T with the type strains of M. canis , M. caseolyticus subsp. caseolyticus and M. caseolyticus subsp. hominis was 23.4, 23.1 and 23.0 % by digital DNA–DNA hybridization and 80.39, 80.45 and 80.87 % by average nucleotide identity (ANI) calculations, confirming that they do not belong to the same species. The DNA G+C content of JEK37T was 35.65 mol%. The novel strains can be differentiated from M. canis KM 45013T by the ability to fermentate d-ribose and by the absence of DNAase production and haemolysis, from M. caseolyticus subsp. caseolyticus CCUG 15606T by the ability to fermentate sucrose and from both species by the inability to grow in 9 and 12% NaCl. They differ from M. caseolyiticus subsp. hominis by the presence of α-glucosidase. The most common fatty acids of JEK37T were C14 : 0, C18 : 1 ω9c and C18 : 0. Known polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, aminolipid, aminoglycolipid, aminophospholipid, glycolipid and phospholipid. Cell-wall peptidoglycan of JEK37T was of type A3α l-Lys–Gly2–L-Ser–Gly (similar to A11.3) and the respiratory quinolone was menaquinone 6. Based on their genotypic and chemotaxonomic characteristics, these strains represent a novel species of the genus Macrococcus , for which we propose the name Macrococcus armenti sp. nov. The type strain is JEK37T (=DSM 112712T=CCOS 1982T).

A Preliminary Study on Antimicrobial Susceptibility of Staphylococcus spp. and Enterococcus spp. Grown on Mannitol Salt Agar in European Wild Boar (Sus scrofa) Hunted in Campania Region-Italy

Simple Summary

During the last decade, an increase in the European wild boar (Sus scrofa) population occurred; thus, over the years, wild boars have become an important potential carrier of pathogenic bacteria for both livestock animals and pets, but also for humans. Since antibiotic resistance has become one of the greatest challenges of global public health, the aim of the present study was to define the prevalence and the antibiotic resistance profiles of bacteria grown on the selective medium mannitol salt agar (MSA), isolated from nasal swabs of wild boars hunted in Campania Region (southern Italy). The most prevalent isolated bacteria were represented by the Staphylococcus spp. and Enterococcus spp. strains, which showed worrying antibiotic-resistant profiles. Consequently, constant surveillance of wild boars is strongly recommended, in order to assess their role as reservoirs of antibiotic resistant bacteria and as sentinels of a possible environmental contamination.

Abstract

The importance of wild boar lies in its role as a bioindicator for the control of numerous zoonotic and non-zoonotic diseases, including antibiotic resistance. Mannitol Salt Agar (MSA) is a selective medium used for isolation, enumeration, and differentiation of pathogenic staphylococci. Other genera such as Enterococcus spp. are also salt tolerant and able to grow on MSA. The present study focused on the identification, by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), of bacteria grown on MSA isolated from the nasal cavities of 50 healthy wild boars hunted in Campania Region (southern Italy) in the year 2019. In addition, the antimicrobial resistance phenotype of the isolated strains was determined by disk diffusion method. Among genus Staphylococcus, coagulase-negative Staphylococcus (CoNS) were the most common isolated species, with Staphylococcus xylosus as the most prevalent species (33.3%). Furthermore, Enterococcus spp. strains were isolated, and Enterococcus faecalis was the species showing the highest frequency of isolation (93.8%). For staphylococci, high levels of resistance to oxacillin (93.3%) were recorded. Differently, they exhibited low frequencies of resistance to tested non-β-lactams antibiotics. Among enterococci, the highest resistances were observed for penicillin (93.7%), followed by ampicillin (75%), and ciprofloxacin (68.7%). Interestingly, 43.7% of the isolated strains were vancomycin-resistant. In conclusion, this study reports the phenotypic antibiotic resistance profiles of Staphylococcus spp. and Enterococcus spp. strains isolated from nasal cavities of wild boars hunted in Campania Region, highlighting that these wild animals are carriers of antibiotic resistant bacteria.

Influence of Tissue Type on the Bacterial Diversity and Community in Pork Bacon

In current study, bacterial diversity and community in different tissues of pork bacon were determined using high-throughput sequencing. In total, six phyla and 111 bacterial genera were identified. Among them, three dominant genera (Staphylococcus, Acinetobacter, and Macrococcus) were shared by all bacon samples. The linear discriminant analysis showed that 24 bacterial taxa significantly differentiated between the tissues. Results of non-metric Multidimensional Scaling and redundancy analysis showed that physicochemical characteristics of the tissue prominently structured the bacterial communities. Network analysis also illustrated that tissue type was an important factor impacting the bacterial interactions in different types of tissue. The results of current study can add valuable insights to the traditional homemade pork bacon.

Description and comparison of the skin and ear canal microbiota of non-allergic and allergic German shepherd dogs using next generation sequencing

Atopic dermatitis is one of the most common skin diseases in dogs. Pathogenesis is complex and incompletely understood. Skin colonizing bacteria likely play an important role in the severity of this disease. Studying the canine skin microbiota using traditional microbiological methods has many limitations which can be overcome by molecular procedures. The aim of this study was to describe the bacterial microbiota of the skin and ear canals of healthy non-allergic and allergic German shepherd dogs (GSDs) without acute flare or concurrent skin infection and to compare both. Bacterial 16S rRNA gene amplicon sequence data revealed no differences of bacterial community patterns between the different body sites (axilla, front dorsal interdigital skin, groin, and ear canals) in non-allergic dogs. The microbiota at the different body sites of non-allergic GSDs showed no significant differences. Only for the samples obtained from the axilla the bacterial microbiota of allergic dogs was characterized by a lower species richness compared to that of non-allergic dogs and the bacterial community composition of the skin and ear canals of allergic dogs showed body site specific differences compared to non-allergic dogs. Actinobacteria was the most abundant phylum identified from the non-allergic dogs and Proteobacteria from allergic dogs. Macrococcus spp. were more abundant on non-allergic skin while Sphingomonas spp. were more abundant on the allergic skin. Forward step redundancy analysis of metadata indicated that the household the dogs came from had the strongest impact on the composition of the skin microbiome followed by sex, host health status and body site.

Technological Applications of Macrococcus caseolyticus and its Impact on Food Safety

Macrococcus spp. are Gram-positive cocci that belong to the Staphylococcaceae family; they are closely related to staphylococci, but, unlike staphylococci, they are not considered as human pathogens. Macrococcus spp. are recognized as relevant veterinary pathogens, and their presence has been reported in food products of animal origin. Macrococcus caseolyticus, the most studied species of the Macrococcus genus, is associated with the development of aroma and flavor in fermented foods and is, thus, used as starter cultures in fermentations. However, certain important issues regarding food safety must be taken into account when employing these microorganisms in fermentations. Recent studies have reported the presence of genes associated with resistance to methicillin and other antibiotics in M. caseolyticus. This can be harmful to human health as these genes can be transferred to other bacteria present in the food, mainly staphylococcal species. This work, therefore, aims to highlight the importance of a more critical view on the presence of macrococci in foods and the possible indirect risks to human health.

Phylogenomic analyses of the Staphylococcaceae family suggest the reclassification of five species within the genus Staphylococcus as heterotypic synonyms, the promotion of five subspecies to novel species, the taxonomic reassignment of five Staphylococcus species to Mammaliicoccus gen. nov., and the formal assignment of Nosocomiicoccus to the family Staphylococcaceae

Phylogenetic analyses based on 16S rRNA gene sequences of members of the family Staphylococcaceae showed the presence of para- and polyphyletic genera. This finding prompted a thorough investigation into the taxonomy of the Staphylococcaceae family by analysing their core genome phylogeny complemented with genome-based indices such as digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity. The resulting data suggested the following proposals: Auricoccus indicus was reduced in taxonomic rank as a later heterotypic synonym of Abyssicoccus albus ; Staphylococcus petrasii subsp. jettensis as a later heterotypic synonym of Staphylococcus petrasii subsp. petrasii ; the unification of Staphylococcus aureus subsp. anaerobius and Staphylococcus aureus subsp. aureus as Staphylococcus aureus ; the unification of Staphylococcus carnosus subsp. utilis and Staphylococcus carnosus subsp. carnosus as Staphylococcus carnosus ; the unification of Staphylococcus saprophyticus subsp. bovis and Staphylococcus saprophyticus subsp. saprophyticus as Staphylococcus saprophyticus ; Staphylococcus succinis subsp. casei as the novel species Staphylococcus casei; Staphylococcus schleiferi subsp. coagulans as the novel species Staphylococcus coagulans; Staphylococcus petrasii subsp. croceilyticus as the novel species Staphylococcus croceilyticus; Staphylococcus petrasii subsp. pragensis as the novel species Staphylococcus pragensis; Staphylococcus cohnii subsp. urealyticus as the novel species Staphylococcus urealyticus; the reassignment of Staphylococcus sciuri , Staphylococcus fleurettii , Staphylococcus lentus , Staphylococcus stepanovicii and Staphylococcus vitulinus to the novel genus Mammaliicoccus with Mammaliicoccus sciuri as the type species; and the formal assignment of Nosocomiicoccus as a member of the family Staphylococcaceae .

Methicillin-Resistant Macrococcus bohemicus Encoding a Divergent SCCmecB Element

A methicillin-resistant Macrococcus isolate from canine otitis, H889678/16/1, was whole-genome sequenced using HiSeq technology to identify the species, antimicrobial resistance determinates and their genomic context. H889678/16/1 belonged to the newly described species Macrococcus bohemicus. It encoded mecB within a novel SCCmec element most similar to that of Macrococcus canis KM45013^T. This SCCmec_H889678/16/1 element also encoded blaZ_m and fusC, but no other resistance determinates were found in the H889678/16/1 genome. The ccrA and ccrB recombinase genes within SCCmec_H889678/16/1 were distinct from those previously described in staphylococci and macrococci and therefore designated here as ccrAm3 and ccrBm3. Our study represents, to the best of our knowledge, the first description of mecB being encoded by M. bohemicus and of methicillin resistance in this species. Furthermore, the SCCmec described here is highly dissimilar to other such elements and encodes novel ccr genes. Our report demonstrates a wider distribution of mecB among Macrococcus species and expands the genomic context in which mecB may be found. The potential for dissemination of mec genes from Macrococcus to related but more pathogenic Staphylococcus species highlights the need to understand the epidemiology of these genes in macrococci.

Staphylococcus arlettae Genomics: Novel Insights on Candidate Antibiotic Resistance and Virulence Genes in an Emerging Opportunistic Pathogen

Coagulase Negative Staphylococci (CoNS) are becoming increasingly recognized as an important cause of human and animal infections. Notwithstanding their clinical relevance, annotation of genes potentially involved in pathogenicity and/or antibiotic resistance in the CoNS species Staphylococcus arlettae (SAR) is currently very limited. In the current work we describe the genome of a novel methicillin resistant isolate of SAR, which we named Bari, and present a comprehensive analysis of predicted antibiotic resistance profiles and virulence determinants for all the 22 currently available SAR genomes. By comparing predicted antibiotic resistance and virulence-associated genes with those obtained from a manual selection of 148 bacterial strains belonging to 14 different species of staphylococci and to two “outgroup” species, Bacillus subtilis (BS) and Macrococcus caseoliticus (MC), we derived some interesting observations concerning the types and number of antibiotic resistance-related and virulence-like genes in SAR. Interestingly, almost 50% of the putative antibiotic resistance determinants identified in this work, which include the clinically relevant mec, van, and cls genes, were shared among all the SAR strains herein considered (Bari included). Moreover, comparison of predicted antibiotic resistance profiles suggest that SAR is closely related to well-known pathogenic Staphylococcus species, such as Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE). A similar analysis of predicted virulence factors, revealed that several genes associated with pathogenesis (including, for example, ica, nuc, and ssp), which are commonly found in the genomes of pathogenic staphylococci such as Staphylococcus haemolyticus (SH) and Staphylococcus saprophyticus (SS), are observed also in the SAR strains for which a genomic sequence is available. All in all, we believe that the analyses presented in the current study, by providing a consistent and comprehensive annotation of virulence and antibiotic resistance-related genes in SAR, can constitute a valuable resource for the study of molecular mechanisms of opportunistic pathogenicity in this species.

A rapid PCR-based method to discriminate Macrococcus caseolyticus and Macrococcus canis from closely-related Staphylococcus species based on the ctaC gene sequence

Our method exploits the amplification of the cytochrome c oxidase subunit II (ctaC) gene for the screening of Macrococcus caseolyticus and Macrococcus canis in complex microbial communities, and discriminating these species from strains of their sister genus Staphylococcus. Thirteen novel strains of these species were isolated using this approach.