Prevalence and antimicrobial resistance trends among vaginal bacteria isolates from pregnant bitches.

Many of the reproductive tract infections in the bitches are caused by bacteria that can normally be present on the vaginal mucosa. These bacteria also might have an important role as the cause responsible for pregnancy loss and fetal deaths. The choice of antibiotic therapy for the pregnant animal is narrow and represents a severe problem in veterinary practice, especially due to increased antimicrobial resistance. Due to incorrect antimicrobials use in breeding kennels, the aim of the present study was to assess the occurrence of the bacterial flora isolated from the pregnant bitches and their antibiotic sensitivity. The study was carried out at the private Veterinary clinic in Novi Sad, Serbia. The vaginal swabs were taken from 60 bitches diagnosed with pregnancy and were sent to be laboratory tested. Based on the results, the most common isolated pathogens were Staphylococcus pseudintermedius (20%) and beta-hemolytic streptococci (18.33%). Furthermore, significant resistance to antibiotics from beta-lactams group was detected. It is of particular importance that antimicrobial treatment be evidence based in order to reduce the overuse of antimicrobials due to increased concern regarding antimicrobial resistance.

Molecular identification, virulence, and antibiotic-resistant genes characteristics of Staphylococcus spp., isolated from milk samples.

Background: Food safety and food-borne infections are major subjects of global interest. Dairy products are considered as important source for these infections. Aim: The present study was conducted to identify the occurrence and to genotype isolates of Staphylococcus spp. recovered from milk samples in Al-Diwaniyah City, Iraq. Methods: The current study included the collection of 50 milk samples purchased from local stores in the current city. These samples were subjected to bacterial cultivation and biochemical tests. Later, the growth was used to extract the genomic DNA that was exposed to PCR and partial gene sequencing both targeted the 16S rRNA gene at a specific genetic piece. Results: The PCR results demonstrated the amplification of the genetic fragment of five genetic clusters for each of Staphylococcus aureus (SAD11, SAD12, SAD13, SAD14, and SAD15), Staphylococcus epidermidis (SED1, SED2, SED3, SED4, and SED5), and Staphylococcus intermedius (SID1, SID2, SID3, SID4, and SID5). The PCR products were sent out to sequencing and reported that the current isolates were similar in their genetic content with global isolates at 95.34% to 97.59%, 96.21% to 97.57%, and 96.09% to 97.88%, respectively, of identity. Conclusion: The present findings show high genetic variations among isolates of S. aureus, S. epidermidis, and S. intermedius recovered from milk samples, and these genotypes are found in different infection settings related to humans and animals, which may pose high risks to humans and animals.

Staphylococcus spp. as part of the microbiota and as opportunistic pathogen in free-ranging black-tuffed marmosets (Callithrix penicillata) from urban areas: Epidemiology, antimicrobial resistance, and pathology.

BACKGROUND: Marmosets (Callithrix sp.), including black-tuffed marmosets (C. penicillata), are neotropical primates that can be highly adapted to urban environments, especially parks and forested areas near cities. Staphylococcus spp. are part of the microbiota of many different hosts and lead to opportunistic severe infection. Isolates from wild animals can be resistant to antimicrobial drugs. However, there are a few studies that evaluated Staphylococcus spp. in neotropical primates. The goal of this study was to evaluate Staphylococcus spp. isolated from free-ranging black-tuffed marmosets. METHODS: Marmosets were captured in six urban parks. After sedation, skin and rectal swabs and feces were sampled. Staphylococcus spp. isolates were identified by MALDI-ToF and their antimicrobial susceptibility was determined. RESULTS: Over 30% of captured individuals were positive for Staphylococcus spp., and S. aureus was the most isolated species followed by Mammaliicoccus (Staphylococcus) sciuri. With the exception of the marmoset subjected to necropsy, none of the other had lesions, which supports that notion that Staphylococcus spp. are members of the microbiota, but also opportunistic pathogens. Most isolates were susceptible to all antimicrobials tested; however, one isolate of S. epidermidis was resistant to multiple antimicrobials (penicillin, cefoxitin, ciprofloxacin, clindamycin, and erythromycin). We considered S. aureus as the main staphylococci to colonize black-tuffed marmosets. CONCLUSIONS: Black-tuffed marmosets can be colonized by several Staphylococcus species, most frequently by S. aureus, and the majority of isolates were sensible to the antimicrobials tested. One S. epidermidis isolate was considered multidrug resistant.

Emergence of Staphylococcus argenteus in pediatrics: Molecular insights from a hospital in East China.

Staphylococcus argenteus is a novel species within the Staphylococcus aureus complex and can cause serious bloodstream infections (BSIs) in humans, which have been mainly reported in adults, especially the elderly. In this study, we analyzed the molecular characterization of a strain of S. argenteus (22WJ8192) isolated from the peripheral vein blood sample of a seven-month-old female infant in Eastern China. The 22WJ8192 belonged to sequence type (ST)2250 and harbored six antibiotic-resistance genes and 53 virulence genes and was resistant to penicillin. Additionally, we conducted a comparative analysis of the molecular characteristics of S. argenteus sourced from various origins within the dataset, predominantly from the National Center for Biotechnology Information Collection (NCBI) genome database. Antibiotic-resistance genes blaR1, blaI_of_Z, blaZ, fosB-Saur, tet(L), aph(3")-IIIa, mecA, and dfrG were more prevalent among the strains of human origin. Virulence genes lukF-PV, sak, sdrE, scn, sdrC, and sdrD were more prevalent among strains of human origin. The presence of antibiotic-resistance genes blaR1, blaI_of_Z, blaZ, fosB-Saur, and aph(3")-IIIa in strain 22WJ8192 was also more common among strains of human origin in the dataset. Conversely, the antibiotic-resistance genes tet(L), mecA, and dfrG, typically found in strains of human origin, were not detected in 22WJ8192. Additionally, virulence genes lukF-PV, sak, sdrE, scn, sdrC, and sdrD present in 22WJ8192 exhibited a higher prevalence among strains of human origin in the dataset. In conclusion, this study emphasizes the potential of S. argenteus ST2250 to induce severe bloodstream infections in infants, shedding light on the molecular characteristics of this strain.

Epidemiology and antibiotic resistance of staphylococci on commercial pig farms in Cape Town, South Africa.

Staphylococci are responsible for a wide range of infections in animals. The most common species infecting animals include Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus intermedius. Recent increases in antibiotic use and antibiotic resistance in animals highlight the need to understand the potential role of commercial livestock as a reservoir of staphylococci and antibiotic resistance genes. Nasal swabs were collected from 143 apparently healthy pigs and 21 pig farm workers, and 45 environmental swabs of feed and water troughs, from two commercial pig farms in the Western Cape, South Africa. Staphylococci were isolated, identified using mass-spectrometry, and antimicrobial susceptibility testing and Illumina whole genome sequencing were performed. One hundred and eighty-five (185) Staphylococcus spp. isolates were obtained, with Mammalicoccus sciuri (n = 57; 31%) being the most common, followed by S. hyicus (n = 40; 22%) and S. aureus (n = 29; 16%). S. epidermidis was predominantly identified in the farm workers (n = 18; 86%). Tetracycline resistance was observed across all species, with rates ranging from 67 to 100%. Majority of M. sciuri isolates (n = 40; 70%) were methicillin resistant, with 78% (n = 31) harbouring mecA. M. sciuri isolates had genes/elements which were associated with SCCmec_type_III (3A) and SCCmec_type_VIII(4A) and were mostly observed in ST61 strains. ST239 strains were associated with SCCmec_type_III(3A). High rates of tetracycline resistance were identified among staphylococci in the pig farms in Western Cape, South Africa. This highlights the need for policy makers to regulate the use of this antibiotic in pig farming.

The relationship between resistance evolution and carbon metabolism in Staphylococcus xylosus under ceftiofur sodium stress.

Staphylococcus xylosus has emerged as a bovine mastitis pathogen with increasing drug resistance, resulting in substantial economic impacts. This study utilized iTRAQ analysis to investigate the mechanisms driving resistance evolution in S. xylosus under ceftiofur sodium stress. Findings revealed notable variations in the expression of 143 proteins, particularly glycolysis-related proteins (TpiA, Eno, GlpD, Ldh) and peptidoglycan (PG) hydrolase Atl. Following the induction of ceftiofur sodium resistance in S. xylosus, the emergence of resistant strains displaying characteristics of small colony variants (SCVs) was observed. The transcript levels of TpiA, Eno, GlpD and Ldh were up-regulated, TCA cycle proteins (ICDH, MDH) and Atl were down-regulated, lactate content was increased, and NADH concentration was decreased in SCV compared to the wild strain. That indicates a potential role of carbon metabolism, specifically PG hydrolysis, glycolysis, and the TCA cycle, in the development of resistance to ceftiofur sodium in S. xylosus.

Integrating multi-wet laboratory diagnostics to study staphylococci in animals in Uganda.

BACKGROUND: Several diagnostic environments in Uganda lack real-time, robust and high-throughput technologies for comprehensive typing of microbes, which is a setback to infectious disease surveillance. This study combined various wet laboratory diagnostics to understand the epidemiology of pathogenic staphylococci isolated from animals in Uganda and the implications for global health security priorities. METHODS: A retrospective study was conducted employing records and pathogenic staphylococci (from animals) archived at the Central Diagnostic Laboratory (CDL), Makerere University, Uganda, between January 2012 and December 2019. The bacteria were speciated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and tested for virulence factors [beta lactamases, lecithinase, deoxyribonuclease (DNase), haemolysins] and resistance to ten antimicrobials of clinical and veterinary relevance. Tetracycline and methicillin resistance genes were also tested. RESULTS: The prevalent diseases were mastitis in cattle and skin infections in dogs. Of the 111 staphylococci tested by MALDI-TOF MS, 79 (71.2%) were Staphylococcus aureus, 27 (24.3%) were Staphylococcus pseudintermedius and 5 (4.5%) were Staphylococcus schleiferi. All these strains expressed haemolysins. The prevalence of strains with lecithinase, penicillinase, cephalosporinase and DNase was 35.9% (14/39), 89.7% (35/39), 0.0% (0/39) and 87.2% (34/39), respectively. Staphylococci were primarily resistant to early penicillins (over 80%), tetracycline (57.7%), and chloramphenicol (46.2%). Minimal resistance was noted with cloxacillin (0.0%), ciprofloxacin (9.6%), and cefoxitin (3.8%). The prevalence of multidrug resistance (MDR) was 78.8% for general staphylococci, 82.2% for S. aureus, 73.1% for S. pseudintermedius, and 60.0% for S. schleiferi. Multidrug resistant staphylococci were significantly more prevalent in the cattle isolates than in the dog isolates (P < 0.05). The prevalence of methicillin-resistant staphylococci (MRS) tested by resistance to cefoxitin and mecA carriage was 3.8%. These four strains were all isolated from dog skin infections. The tetK gene was the most predominant (35.4%), followed by tetM (25.0%). CONCLUSION: In resource-constrained settings, the approach of integrated diagnostics promises sustainable disease surveillance and the addressing of current capacity gaps. The emergence of MRS (zoonotic bacteria) in companion animals creates a likelihood of reduced treatment options for related human infections, a threat to global health.

Coagulase-negative staphylococci from bovine milk: Antibiogram profiles and virulent gene detection.

BACKGROUND: Coagulase-negative Staphylococcus species are an emerging cause of intramammary infection, posing a significant economic and public health threat. The aim of this study was to assess the occurrence of coagulase-negative Staphylococcus species in bovine milk and dairy farms in Northwestern Ethiopia and to provide information about their antibiotic susceptibility and virulence gene profiles. METHODS: The cross-sectional study was conducted from February to August 2022. Coagulase-negative Staphylococcus species were isolated from 290 milk samples. Species isolation and identification were performed by plate culturing and biochemical tests and the antimicrobial susceptibility pattern of each isolate was determined by the Kirby-Bauer disc diffusion test. The single-plex PCR was used to detect the presence of virulent genes. The STATA software version 16 was used for data analysis. The prevalence, proportion of antimicrobial resistance and the number of virulent genes detected from coagulase-negative Staphylococcus species were analyzed using descriptive statistics. RESULTS: Coagulase-negative Staphylococcus species were isolated in 28.6%, (95% CI: 23.5-34.2) of the samples. Of these, the S. epidermidis, S. sciuri, S. warneri, S. haemolyticus, S. simulans, S. chromogens, S. cohnii, and S. captis species were isolated at the rates of 11, 5.2, 3.4, 3.1, 3.1, 1, 1, and 0.7% respectively. All the isolates showed a high percentage (100%) of resistance to Amoxicillin, Ampicillin, and Cefotetan and 37.5% of resistance to Oxacillin. The majority (54.2%) of coagulase-negative isolates also showed multidrug resistance. Coagulase-negative Staphylococcus species carried the icaD, pvl, mecA, hlb, sec, and hla virulent genes at the rates of 26.5%, 22.1%, 21.7%, 9.6%, 9.6% and 8.4% respectively. CONCLUSION: The present study revealed that the majority of the isolates (54.2%) were found multidrug-resistant and carriage of one or more virulent and enterotoxin genes responsible for intramammary and food poisoning infections. Thus, urgent disease control and prevention measures are warranted to reduce the deleterious impact of coagulase-negative species. To the best of our knowledge, this is the first study in Ethiopia to detect coagulase-negative Staphylococcus species with their associated virulent and food poisoning genes from bovine milk.

Emergence of novel methicillin resistant Staphylococcus pseudintermedius lineages revealed by whole genome sequencing of isolates from companion animals and humans in Scotland.

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs, and infection in humans is increasingly found, often linked to contact with dogs. We conducted a retrospective genotyping and antimicrobial susceptibility testing study of 406 S. pseudintermedius isolates cultured from animals (dogs, cats and an otter) and humans across Scotland, from 2007 to 2020. Seventy-five sequence types (STs) were identified, among the 130 isolates genotyped, with 59 seen only once. We observed the emergence of two methicillin resistant Staphylococcus pseudintermedius (MRSP) clones in Scotland: ST726, a novel locally-evolving clone, and ST551, first reported in 2015 in Poland, possibly linked to animal importation to Scotland from Central Europe. While ST71 was the most frequent S. pseudintermedius strain detected, other lineages that have been replacing ST71 in other countries, in addition to ST551, were detected. Multidrug resistance (MDR) was detected in 96.4% of MRSP and 8.4% of MSSP. A single MRSP isolate was resistant to mupirocin. Continuous surveillance for the emergence and dissemination of novel MDR MRSP in animals and humans and changes in antimicrobial susceptibility in S. pseudintermedius is warranted to minimise the threat to animal and human health.

Light-activated conjugated polymer nanoparticles to defeat pathogens associated with bovine mastitis.

Bovine mastitis (BM) represents a significant challenge in the dairy industry. Limitations of conventional treatments have prompted the exploration of alternative approaches, such as photodynamic inactivation (PDI). In this study, we developed a PDI protocol to eliminate BM-associated pathogens using porphyrin-doped conjugated polymer nanoparticles (CPN). The PDI-CPN protocol was evaluated in four mastitis isolates of Staphylococcus and in a hyper-biofilm-forming reference strain. The results in planktonic cultures demonstrated that PDI-CPN exhibited a bactericidal profile upon relatively low light doses (∼9.6 J/cm2). Furthermore, following a seven-hour incubation period, no evidence of cellular reactivation was observed, indicating a highly efficient post-photodynamic inactivation effect. The successful elimination of bacterial suspensions encouraged us to test the PDI-CPN protocol on mature biofilms. Treatment using moderate light dose (∼64.8 J/cm2) reduced biofilm biomass and metabolic activity by up to 74% and 88%, respectively. The impact of PDI-CPN therapy on biofilms was investigated using scanning electron microscopy (SEM), which revealed nearly complete removal of the extracellular matrix and cocci. Moreover, ex vivo studies conducted on bovine udder skin demonstrated the efficacy of the therapy in eliminating bacteria from these scaffolds and its potential as a prophylactic method. Notably, the histological analysis of skin revealed no signs of cellular degeneration, suggesting that the protocol is safe and effective for BM treatment. Overall, this study demonstrates the potential of PDI-CPN in treating and preventing BM pathogens. It also provides insights into the effects of PDI-CPN on bacterial growth, metabolism, and survival over extended periods, aiding the development of effective control strategies and the optimization of future treatments.

Structural Diversification of Pyrazinone Metabolites via Spontaneous Oxa-Michael Addition in Staphylococcus xylosus.

A family of pyrazinone metabolites (1-11) were characterized from Staphylococcus xylosus ATCC 29971. Six of them were hydroxylated or methoxylated, which were proposed to be produced by the rare noncatalytic oxa-Michael addition reaction with a water or methanol molecule. It was confirmed that isopropyl alcohol can also be the Michael donor of the reaction. 1-7 and the synthetic precursor 2a showed significant inhibition of breast cancer cell migration.

Prevalence, genetic characteristics, and antimicrobial resistance of staphylococcal isolates from oral cavity and skin surface of healthy individuals in northern Japan.

BACKGROUND: Oral cavity is an ecological niche for colonization of staphylococci, which are a major bacterial species causing community-acquired infections in humans. In this study, prevalence, and characteristics of staphylococci in oral cavity and skin of healthy individuals were investigated in northern Japan. METHODS: Saliva from oral cavity and swab from skin surface of hand were collected and cultured on selective media. Species of the isolates were identified genetically, and ST was determined for S. aureus and S. argenteus. Genes associated with antimicrobial resistance were detected by PCR. RESULTS: Among 166 participants, a total of 75 S. aureus isolates were obtained from 61 individuals (37 %), and recovered more frequently in oral cavity (n = 48) than skin (n = 27). Among 23 STs identified in S. aureus isolates, ST8 (CC8), ST15 (CC15), and ST188 (CC1) were the most common (10 isolates each), with STs of CC1 being dominant (17 isolates). Methicillin-resistant S. aureus (MRSA) was isolated in the skin of two individuals and belonged to ST1 and ST6. Resistance to erythromycin and gentamicin associated with erm(A) and aac(6')-Ie-aph(2")-Ia, respectively, was more commonly found in ST5 and ST8 isolates. One S. argenteus isolate (ST2250, mecA-negative) was recovered from oral cavity of a participant (0.6 %). A total of 186 isolates of coagulase-negative staphylococci (CoNS) were recovered from 102 participants and identified into 14 species, with S. warneri being the most common (n = 52), followed by S. capitis (n = 42), S. saprophyticus (n = 20) and S. haemolyticus (n = 19). mecA was detected in S. saprophyticus, S. haemolyticus, and S. caprae, while arginine-catabolic mobile element (ACME) in only S. capitis and S. epidermidis. CONCLUSION: S. aureus was more prevalent in oral cavity than skin surface, belonging to three major STs, with CC1 being a dominant lineage. The prevalence of antimicrobial resistance was distinct depending on CoNS species.

Identification and antimicrobial susceptibility profiles of Staphylococcus species isolated from raw cow milk, and swabs in smallholder dairy farms in Meta district, Eastern Ethiopia.

BACKGROUND: The safety of milk production in terms of foodborne infections is a worldwide issue, particularly in developing countries where production is often unhygienic. A cross-sectional study was conducted from December 2018 to August 2019 in the Meta District of Eastern Hararghe Zone, Oromia Regional State, Ethiopia. We aim to assess milk hygiene practices among smallholder dairy farmers, estimate the prevalence of Staphylococcus aureus in raw cow milk and swabs, assess associated risk factors, and the antimicrobial susceptibility test of S. aureus isolates. Face-to-face interviews with 30 respondents randomly selected from smallholder dairy farmers were used to assess the potential risk factors for S. aureus contaminations in milk. A total of 177 samples were examined using standard microbiological testing. The disc diffusion technique was also employed to assess the antibiotic susceptibility of the isolates. The data was analyzed using STATA® version 14.0 statistical software. RESULTS: According to the milk hygiene assessment, 80% of respondents did not wash cow udder before milking, did not use detergent to clean milk containers, and did not keep milk refrigerated before consumption or sale, while 63.3% of milk consumers ingested raw milk. They had never heard of staphylococci foodborne disease. Likewise, the overall prevalence of S. aureus was 12.42% (95%CI: 8.32-18.98). The prevalence of S. aureus in udder milk, equipment swabs, and milkers' hands was 18.8%, 26.7%, and 30%, respectively. The prevalence of S. aureus in milk is significantly associated with age, and mastitis history (p < 0.05). Moreover, old and mastitis positive animals were eight (OR: 8.40; 95%CI: 1.68-41.89) and four (OR: 4.33; 95%CI: 1.37-13.66) times more likely to be infected by S. aureus than adult, and mastitis negative animal. The isolates were resistant to penicillin G (97.4%) and tetracycline (69.2%) whereas susceptible to kanamycin, streptomycin, vancomycin, and cefotaxime, at 84.6%, 71.8%, 64%, and 58.8%, respectively. CONCLUSION: This study revealed the presence of antimicrobial-resistant patterns of S. aureus on commonly used antibiotics, as well as inadequate milk handling practices in the study area. Thus, awareness should be created on proper milk handling and hygiene as well as appropriate uses of antibiotics should be encouraged.

Evaluation of Vitek-2 and MicroScan ASTs directly from positive blood culture: A cost-effective 24-h reduction for Enterobacterales and staphylococci.

The reduction of antimicrobial susceptibility testing (AST) time-to-result is a central need, especially in sepsis treatment. The current automated rapid ASTs are still too expensive for many laboratories. We aimed to evaluate three pre-treatment methods for a same-day inoculation on both automated AST platforms available in our laboratory. We tested 100 Enterobacterales or staphylococci positive bottles. We obtained good results with the different methods and instruments. In particular, Vitek-2 showed good performances with Enterobacterales AST when inoculated with bacterial pellet (96.6% categorical agreement - CA-, 93.3% essential agreement - EA). Also short-term incubation colonies for staphylococci AST had acceptable CA (94.2%), even if with 77.5% EA. MicroScan system for staphylococci AST with both short-term incubation and direct blood inoculation reached >95% CA, but 92.5% and 83.6% EA, respectively. On the other hand, Enterobacterales AST showed optimal performances only with bacterial pellet inoculation (97.6% CA). In fact, direct blood inoculation showed not acceptable parameters for several molecules. Both systems allow a 24-h reduction in time-to-result, by using the same instruments of routine activity after rapid and cheap pre-treatments.

Performance evaluation of cefoxitin screen test on two different automated antimicrobial susceptibility test systems: a comparative study.

Reliable detection of mecA and mecC-mediated beta-lactam resistance using automated antimicrobial susceptibility test systems is critical for patient care. The aim of this study was to compare the performance of the new cefoxitin screen test (oxsf02n) on the Vitek 2 card (Vitek 2) and BD Phoenix PMC-100 Gram-Positive AST Panel (Phoenix) against the reference method for the detection of mecA (and mecC)-mediated beta-lactam resistance. Two hundred fifty clinical fresh and stock Staphylococcus spp. isolates were included. There were 120 mecA-positive, 10 mecC-positive, and 120 mecA and mecC-negative isolates. Cefoxitin screen and oxacillin tests were performed on Vitek 2 and Phoenix and by their respective reference methods (disk diffusion for the cefoxitin screen test and broth microdilution for oxacillin) for all isolates. PCR testing was also performed to confirm the presence of mecA and/or mecC genes. Results from each system were compared to the reference methods. Statistical hypotheses were evaluated both for Vitek 2 compared to the reference methods and Vitek 2 compared to the Phoenix. Compared to the reference method, the Vitek 2 cefoxitin screen test had 100% sensitivity/98% specificity and the Phoenix cefoxitin screen test had 84% sensitivity/100% specificity for the detection of mecA (and mecC)-mediated beta-lactam resistance. When the oxacillin test was combined with the cefoxitin screen for Vitek 2, the sensitivity and specificity were unchanged. However, when the oxacillin and cefoxitin screen tests were combined for the Phoenix, the sensitivity increased to 100% and the specificity remained unchanged (100%). When considering cefoxitin alone, the Vitek 2 screen test showed a higher sensitivity than the Phoenix for the detection of mecA and mecC-mediated beta-lactam resistance. However, currently, both systems use a combination of the cefoxitin and oxacillin tests to interpret the final result, and both reached a high level of performance when cefoxitin and oxacillin results were combined.IMPORTANCEThis research marks the inaugural evaluation of the revamped cefoxitin screen test version in Vitek 2, juxtaposing it against reference methods and a primary competitor BD Phoenix.

Synthesis and Photophysical Characterization of Fluorescent Naphtho[2,3-d]thiazole-4,9-Diones and Their Antimicrobial Activity against Staphylococcus Strains.

The chemical reaction of 2-(methylsulfinyl)naphtho[2,3-d]thiazole-4,9-dione (3) using different amines, including benzylamine (4a), morpholine (4b), thiomorpholine (4c), piperidine (4d), and 4-methylpiperazine (4e), produced corresponding new tricyclic naphtho[2,3-d]thiazole-4,9-dione compounds (5a-e) in moderate-to-good yields. The photophysical properties and antimicrobial activities of these compounds (5a-e) were then characterized. Owing to the extended π-conjugated system of naphtho[2,3-d]thiazole-4,9-dione skeleton and substituent effect, 5a-e showed fluorescence both in solution and in the solid state. The introduction of nitrogen-containing heterocycles at position 2 of the thiazole ring on naphtho[2,3-d]thiazole-4,9-dione led to large bathochromic shifts in solution, and 5b-e exhibited orange-red fluorescence with emission maxima of over 600 nm in highly polar solvents. Staphylococcus aureus (S. aureus) is a highly pathogenic bacterium, and infection with its antimicrobial-resistant pathogen methicillin-resistant S. aureus (MRSA) results in serious clinical problems. In this study, we also investigated the antimicrobial activities of 5a-e against S. aureus, MRSA, and S. epidermidis. Compounds 5c with thiomorpholine group and 5e with 4-methylpiperazine group showed potent antimicrobial activity against these bacteria. These results will lead to the development of new fluorescent dyes with antimicrobial activity in the future.

Phenotypic and genotypic characterization of commensal staphylococci isolated from young volunteers in Alexandria, Egypt.

Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus aureus and Staphylococci other than S. aureus (SOSA) among young volunteers in Egypt to determine their risk potential. Nasal swabs collected over 1 week in June 2019 from 196 volunteers were cultured for staphylococcus isolation. The participants were interviewed to assess sex, age, general health, hospitalization and personal hygiene habits. Identification was carried out using biochemical tests and VITEK 2 automated system. Disc diffusion and minimum inhibitory concentration tests were performed to determine antibiotic susceptibility. Screening for macrolide resistance genes (ermA, ermB, ermC, ermT and msrA) was performed using polymerase chain reaction. Thirty four S. aureus and 69 SOSA were obtained. Multi-drug resistance (MDR) was detected among most staphylococcal species, ranging from 30.77% among S. hominis to 50% among S. epidermidis. Phenotypic resistance to all tested antibiotics, except for linezolid, was observed. Susceptibility to rifampicin, vancomycin and teicoplanin was highest. ermB showed the highest prevalence among all species (79.41% and 94.2% among S. aureus and SOSA, respectively), and constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance was equally observed in S. aureus and SOSA (11.11% and 16.22%, respectively), whereas inducible MLSB resistance was more often found in S. aureus (77.78% and 43.24%, respectively). The species or resistance level of the carried isolates were not significantly associated with previous hospitalization or underlying diseases. Although over all colonization and carriage of resistance genes are within normal ranges, the increased carriage of MDR S. aureus is alarming. Also, the fact that many macrolide resitance genes were detected should be a warning sign, particularly in case of MLSB inducible phenotype. More in depth analysis using whole genome sequencing would give a better insight into the MDR staphylococci in the community in Egypt.

Exploring therapeutic options for mild diabetic-related foot infections: a comparative in vitro study of cefditoren versus amoxicillin/clavulanic acid.

Skin and soft tissue infections (SSTIs), and particularly diabetic-related foot infections (DFI), present diagnostic and therapeutic complexities, often leading to severe complications. This study aims to evaluate the in vitro efficacy of cefditoren and amoxicillin/clavulanic acid against typical DFI pathogens. Clinical samples from 40 patients with mild SSTIs were analyzed, revealing a predominance of Staphylococcus spp. and Streptococcus spp. species. Cefditoren exhibited activity against 90% of isolates, with superior potency over amoxicillin/clavulanic acid. These findings underscore the utility of cefditoren in empirical treatment of DFI, although a larger sample size would be desirable for further validation.

Enhancement of colour formation of fermented sausages by overexpression of nitric oxide synthase in Staphylococcus vitulinus under hydrogen peroxide stress.

This study used hydrogen peroxide (H2O2) treatment to overexpress the gene of nitric oxide synthase (nos) in Staphylococcus vitulinus, which was then inoculated into fermented sausages to observe its effect on colour development. The results showed that a low concentration of H2O2 (50 mM) could up-regulate the expression of nos by increasing the oxidative stress level of S. vitulinus. At 2 h after treatment, the expression of nos in S. vitulinus was the highest (P < 0.05), and the relative enzyme activity was increased to about 1.5 times that of the untreated. The growth of S. vitulinus was not substantially affected by 50-mM H2O2 treatment (P > 0.05). When H2O2-treated S. vitulinus was inoculated into fermented sausages, the content of nitrosomyoglobin was increased, and the a*-value (indicating redness) was not significantly different from that in the group treated with nitrite (P > 0.05). This study provides a potential method to enhance the ability of S. vitulinus for colourising fermented sausage by inducing the overexpression of nos.

Chromosomal and plasmid localization of ileS2 in high-level mupirocin-resistant Staphylococcus pseudintermedius and Staphylococcus aureus isolated from canine and feline origins.

OBJECTIVES: To characterize the mobile genetic elements and genetic localization of ileS2 in high-level mupirocin-resistant (Hi-MupR) methicillin-resistant Staphylococcus pseudintermedius (MRSP) and MRSA isolates recovered from canine and feline clinical samples. METHODS: The identification of bacterial species and presence of mecA and ileS2 genes in MRSP and MRSA isolates were performed using MALDI-TOF MS and PCR, respectively. Antimicrobial resistance (AMR) phenotypes were determined by broth microdilution assays. The genome characteristics, ileS2-containing elements and staphylococcal cassette chromosome mec (SCCmec) were illustrated using complete circular genomes obtained from hybrid assembly of Illumina short-reads and Oxford Nanopore Technologies long-reads. These were analysed through phylogenetic and bioinformatics approaches. RESULTS: A total of 18 MRSP clinical isolates and four MRSA clinical isolates exhibited the Hi-MupR phenotype and carried multiple AMR genes, including mecA and ileS2 genes. MRSP ST182-SCCmec V (n = 6) and ST282-ΨSCCmec57395-t10 (n = 4) contained the ileS2 transposable unit associated with IS257 on the chromosome. Three MRSA ST398-SCCmec V-t034/t4652 isolates carried ∼42 kb pSK41-like ileS2 plasmids, whereas similar ileS2 plasmids lacking tra genes were found in MRSP ST282-ΨSCCmec57395-t72/t21 isolates. Furthermore, a new group of ileS2 plasmids, carried by MRSP ST45-ΨSCCmec57395, ST433-ΨSCCmecKW21-t05 and ST2165-SCCmec IV-t06, and by one MRSA ST398-SCCmec V-t034 strain, shared the plasmid backbone with the cfr/fexA-carrying plasmid pM084526_1 in MRSA ST398. CONCLUSIONS: This study provides the first evidence of ileS2 integration into the S. pseudintermedius chromosome, which is a rare occurrence in staphylococcal species, and plasmids played a pivotal role in dissemination of ileS2 in both staphylococcal species.