Investigation of methicillin-resistant Staphylococcus aureus among clinical isolates from humans and animals by culture methods and multiplex PCR

Phytochemistry, Antibacterial and Antioxidant Activities of Grewia lasiocarpa E. Mey. Ex Harv. Fungal Endophytes: A Computational and Experimental Validation Study

The genus Grewia are well-known for their medicinal properties and are widely used in traditional remedies due to their rich phytochemical composition and potential health benefits. This study isolated and characterized five endophytic fungi from Grewia lasiocarpa E. Mey. Ex Harv. and evaluated their in vitro antibacterial and antioxidant activities. Five [Aspergillus fumigatus (MK243397.1), A. fumigatus (MK243451.1), Penicillium raistrickii (MK243492.1), P. spinulosum (MK243479.1), Meyerozyma guilliermondii (MK243634.1)] of the 22 isolated endophytic fungi had inhibitory activity (62.5-1000 µg/mL) against methicillin-resistant Staphylococcus aureus (MRSA). The antioxidant activities were 66.5% and 98.4% for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP), respectively. In silico evaluation of the phytochemicals of the extract (containing majorly n-hexadecanoic acid) was performed against penicillin-binding protein 2a (PBP2a) implicated in the broad clinical resistance of MRSA to conventional beta-lactams. Molecular docking and molecular dynamic simulation analyses revealed that the phytosterol constituents of the extract, especially dehydroergosterol (-46.28 kcal/mol), had good stability (4.35 Å) and compactness (35.08 Å) with PBP2a relative to the unbound PBP2a and amoxicillin-PBP2a complex during the 100 ns simulation period, reinforcing them as putative leads that may be developed as viable alternatives to beta-lactams against infections caused by MRSA. However, the prediction that dehydroergosterol lacks oral bioavailability with poor water solubility suggests that it could benefit from structural optimization for improved druggability. Hence, isolating and derivatizing dehydroergosterol for subsequent evaluation against PBP2a in vitro and in vivo is highly recommended.

Deciphering the genomic character of the multidrug-resistant Staphylococcus aureus from Dhaka, Bangladesh

Staphylococcus aureus is one of the leading agents of nosocomial and community-acquired infections. In this study, we explored the genomic characterization of eight methicillin-resistant clinical isolates of S. aureus from Dhaka, Bangladesh. Notably, all strains were resistant to penicillin, cephalosporins, and monobactams, with partial susceptibility to meropenem and complete susceptibility to amikacin, vancomycin, and tigecycline antibiotics. The strains were found to have an average genome size of 2.73 Mbp and an average of 32.64% GC content. Multi-locus sequence typing analysis characterized the most predominant sequence type as ST361, which belongs to the clonal complex CC361. All isolates harbored the mecA gene, often linked to SCCmec_type IV variants. Multidrug resistance was attributed to efflux pumps NorA, NorC, SdrM, and LmrS alongside genes encoding beta-lactamase BlaZ and factors like ErmC and MepA. Additionally, virulence factors including adsA, sdrC, cap8D, harA, esaA, essC, isdB, geh, and lip were commonly identified. Furthermore, genes associated with heme uptake and clumping were present, highlighting their roles in S. aureus colonization and pathogenesis. Nine secondary metabolite biosynthetic gene clusters were found, of which six were common in all the strains. Numerous toxin-antitoxin systems were predicted, with ParE and ParB-like nuclease domains found to be the most prevalent toxin and antitoxin, respectively. Pan-genome analysis revealed 2007 core genes and 229 unique genes in the studied strains. Finally, the phylogenomic analysis showed that most Bangladeshi strains were grouped into two unique clades. This study provides a genomic and comparative insight into the multidrug resistance and pathogenicity of S. aureus strains, which will play a crucial role in the future antibiotic stewardship of Bangladesh.

Unknown spa types, spa repeats, and relatedness of MRSA isolated from horses, dogs, cats, and their human handlers

Methicillin resistant Staphylococcus aureus (MRSA) represents a worrying example of antimicrobial resistance, and it is essential to acquire new information to monitor the spread and limit it further diffusion. This study aimed to characterise 22 MRSA isolates from horses, dogs, cats, and their human handlers focusing on spa typing. In the analysis of the sequences obtained, the spa type is "unknown" (unidentified) and all the sequences except one had repeats previously not known in all databases potentially indicating new spa-repeats. This could possibly indicate either permanent import of novel spa types or in-house microevolution of spa repeats.

Promising bioprocesses for the efficient removal of antibiotics and antibiotic-resistance genes from urban and hospital wastewaters: Potentialities of aerobic granular systems

The use, overuse, and improper use of antibiotics have resulted in higher levels of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs), which have profoundly disturbed the equilibrium of the environment. Furthermore, once antibiotic agents are excreted in urine and feces, these substances often can reach wastewater treatment plants (WWTPs), in which improper treatments have been highlighted as the main reason for stronger dissemination of antibiotics, ARB, and ARGs to the receiving bodies. Hence, achieving better antibiotic removal capacities in WWTPs is proposed as an adequate approach to limit the spread of antibiotics, ARB, and ARGs into the environment. In this review, we highlight hospital wastewater (WW) as a critical hotspot for the dissemination of antibiotic resistance due to its high level of antibiotics and pathogens. Hence, monitoring the composition and structure of the bacterial communities related to hospital WW is a key factor in controlling the spread of ARGs. In addition, we discuss the advantages and drawbacks of the current biological WW treatments regarding the antibiotic-resistance phenomenon. Widely used conventional activated sludge technology has proved to be ineffective in mitigating the dissemination of ARB and ARGs to the environment. However, aerobic granular sludge (AGS) technology is a promising technology-with broad adaptability and excellent performance-that could successfully reduce antibiotics, ARB, and ARGs in the generated effluents. We also outline the main operational parameters involved in mitigating antibiotics, ARB, and ARGs in WWTPs. In this regard, WW operation under long hydraulic and solid retention times allows better removal of antibiotics, ARB, and ARGs independently of the WW technology employed. Finally, we address the current knowledge of the adsorption and degradation of antibiotics and their importance in removing ARB and ARGs. Notably, AGS can enhance the removal of antibiotics, ARB, and ARGs due to the complex microbial metabolism within the granular biomass.

Review of antibiotic use and resistance in food animal production in WHO South-East Asia Region

Antimicrobial resistance is an emerging global threat to public health. The resistant bacteria in food animals can be transferred to humans through the food chain. Limited information on antimicrobial usage and resistance in food animals is available in Southeast Asia due to inadequate monitoring or surveillance systems. A literature review was conducted on antimicrobial use and resistance in food animal production in Southeast Asia for the period 2011-2020, to assess the scope and extent of antibiotic use and resistance. The countries included in the study were Bangladesh, Bhutan, Democratic People's Republic of Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste. The information was categorised by country, production type and findings regarding antibiotic use and resistance. A total of 108 publications were included in the review. Results showed widespread use of critically and highly important antibiotics in livestock, poultry and aquacultured fish and their products. To curb the growing threat of antibiotic resistance, Southeast Asian countries need to strengthen surveillance and regulatory controls of antimicrobial use in food animal production through "One Health" approach.

Antimicrobial resistance patterns of Staphylococcus aureus isolated from apparently healthy pet cats of Bangladesh

Objective

This study sought to determine the occurrence, molecular identification, antimicrobial-resistant trends, and gene distribution of Staphylococcus aureus in pet cats and their owners' hand swabs.

Materials and Methods

From different places and clinics in Mymensingh and Dhaka, 168 pet cat samples and 42 hand swab samples from cat owners were obtained. The organisms were scrutinized by assessing the outcomes using conventional and molecular techniques. The disc diffusion technique was applied to find the resistance pattern against 12 antibiotics, and genes were discovered by targeting specific genes using PCR.

Results

The occurrence of pathogenic S. aureus in pet cats was 7.74%, while it was 9.50% in pet owners' hand swabs, and 25.0% of the pet owner's hand swabs contained these genes. Staphylococcus aureus was utterly resistant to amoxicillin, ampicillin, cefixime, erythromycin, and imipenem in both pet cat and hand swabs of pet owner samples. All S. aureus isolates had a multidrug-resistant phenotype, and 1 from pet cats (O19) and 1 from pet owner hand swabs (H9) were resistant to all 12 antibiotics in the 7 antimicrobial classes. Several antibiotic-resistance genes were detected by PCR.

Conclusion

The study confirmed multidrug-resistant pathogenic S. aureus in pet cats and their owners in Bangladesh, indicating a major health risk to both people and cats. Thus, a holistic and integrated one-health approach between veterinary and medical specialists is needed to mitigate the global distribution of these zoonotic antibiotic-resistant S. aureus strains.

Molecular Characterization of Staphylococcus aureus Complex Isolated from Free-Ranging Long-Tailed Macaques at Kosumpee Forest Park, Maha Sarakham, Thailand

The Staphylococcus (S.) aureus complex, including methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA), and S. argenteus are bacterial pathogens that are responsible for both human and animal infection. However, insights into the molecular characteristics of MRSA, MSSA, and S. argenteus carriages in wildlife, especially in long-tailed macaques, rarely have been reported in Thailand. The objective of this study was to assess molecular characterization of MRSA, MSSA, and S. argenteus strains isolated from free-ranging long-tailed macaques (Macaca fascicularis) at Kosumpee Forest Park, Maha Sarakham, Thailand. A total of 21 secondary bacterial isolates (including 14 MRSA, 5 MSSA, and 2 S. argenteus) obtained from the buccal mucosa of 17 macaques were analysed by a Polymerase chain reaction (PCR) to identify several virulence genes, including pvl, tst, hla, hlb clfA, spa (x-region), spa (IgG biding region), and coa. The most prevalent virulence genes were clfA, coa, and the spa IgG biding region which presented in all isolates. These data indicated that MRSA, MSSA, and S. argenteus isolates from the wild macaques at Kosumpee Forest Park possess a unique molecular profile, harbouring high numbers of virulence genes. These findings suggest that wild macaques may potentially serve as carriers for distribution of virulent staphylococcal bacteria in the study area.

Pet animals as reservoirs for spreading methicillin-resistant Staphylococcus aureus to human health

Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of pathogenic bacteria that is a major problem in the world's health. Due to their frequent interaction with humans, pets are one of the main risk factors for the spread of MRSA. The possibility for zoonotic transmission exists since frequently kept dogs and cats are prone to contract MRSA and act as reservoirs for spreading MRSA. The mouth, nose, and perineum are the primary locations of MRSA colonization, according to the findings of MRSA identification tests conducted on pets. The types of MRSA clones identified in cats and dogs correlated with MRSA clones infecting humans living in the same geographic area. A significant risk factor for the colonization or transmission of MRSA is human-pet contact. An essential step in preventing the spread of MRSA from humans to animals and from animals to humans is to keep hands, clothing, and floor surfaces clean.

Prevalence and multidrug-resistant profile of methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius in dogs, cats, and pet owners in Malaysia

Background and Aim

Staphylococcus aureus and Staphylococcus pseudintermedius are widespread skin and mucous membrane colonizers and may cause opportunistic infections in humans and animals. This study aimed to identify and characterize methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) isolates from domestic and stray dogs and cats and pet owners in Malaysia using molecular epidemiology and antimicrobial profiling.

Materials and Methods

Three hundred and fifty oral and nasal swabs were taken from pet and stray dogs and cats and pet owners; all samples were subjected to culture and biochemical tests and polymerase chain reaction; the selected isolates were put through disk diffusion test and multilocus sequence typing.

Results

One S. aureus isolate and three S. pseudintermedius isolates were identified as MRSA and MRSP, respectively, of which the MRSA isolate and one of the MRSP isolates showed multidrug resistance and the remaining two MRSP isolates were resistant to one or two antimicrobials. Multilocus sequence typing showed that the MRSA isolate belongs to clonal complex (CC) 789, while for the MRSP isolates, two were in CC45 and one was a singleton.

Conclusion

This study is the first study in Malaysia to perform molecular characterization of MRSP isolated from pet dogs and cats and pet owners. The outcomes of this study reveal that even healthy pet dogs and cats and their owners can be carriers of drug-resistant staphylococci, highlighting the role of pets and pet owners as carriers of MRSA and MRSP in Malaysia.

Prevalence and multidrug-resistant profile of methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius in dogs, cats, and pet owners in Malaysia

Background and Aim: Staphylococcus aureus and Staphylococcus pseudintermedius are widespread skin and mucous membrane colonizers and may cause opportunistic infections in humans and animals. This study aimed to identify and characterize methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) isolates from domestic and stray dogs and cats and pet owners in Malaysia using molecular epidemiology and antimicrobial profiling. Materials and Methods: Three hundred and fifty oral and nasal swabs were taken from pet and stray dogs and cats and pet owners; all samples were subjected to culture and biochemical tests and polymerase chain reaction; the selected isolates were put through disk diffusion test and multilocus sequence typing. Results: One S. aureus isolate and three S. pseudintermedius isolates were identified as MRSA and MRSP, respectively, of which the MRSA isolate and one of the MRSP isolates showed multidrug resistance and the remaining two MRSP isolates were resistant to one or two antimicrobials. Multilocus sequence typing showed that the MRSA isolate belongs to clonal complex (CC) 789, while for the MRSP isolates, two were in CC45 and one was a singleton. Conclusion: This study is the first study in Malaysia to perform molecular characterization of MRSP isolated from pet dogs and cats and pet owners. The outcomes of this study reveal that even healthy pet dogs and cats and their owners can be carriers of drug-resistant staphylococci, highlighting the role of pets and pet owners as carriers of MRSA and MRSP in Malaysia. Keywords: antimicrobial resistance, antimicrobial susceptibility testing, methicillin resistance, multilocus sequence typing, public health, zoonotic infections.

Clonal relatedness of coagulase-positive staphylococci among healthy dogs and dog-owners in Spain. Detection of multidrug-resistant-MSSA-CC398 and novel linezolid-resistant-MRSA-CC5

Introduction

Nasal carriage of coagulase-positive staphylococci (CoPS) in healthy dogs could indicate increased risks of colonization for in-contact people or vice versa. This study determined the nasal carriage rate of CoPS among healthy dogs and in-contact people, their genotypic characteristics and phylogenetic relatedness.

Methods

Nasal samples were collected from 27 households (34 dogs and 41 humans) in Spain. Staphylococci were identified by MALDI-TOF-MS, their antimicrobial resistance (AMR) genes and spa-types were tested by PCR/sequencing. The relatedness of CoPS from the same households was assessed by core genome single nucleotide polymorphisms (SNPs) analyses.

Results

Staphylococcus aureus carriage was found in 34.1% of humans (including one methicillin-resistant S. aureus MRSA-CC5-t2220-SCCmec type-IV2B) and 5.9% of dogs; Staphylococcus pseudintermedius in 2.4% of humans and 32.4% of dogs; while Staphylococcus coagulans was only detected in dogs (5.4%). Remarkably, one human co-carried S. aureus/S. pseudintermedius, while a dog co-carried the three CoPS species. Household density was significantly associated with S. pseudintermedius carriage in households with > than 1 dog and >than 1 human (OR = 18.10, 95% CI: 1.24-260.93, p = 0.034). Closely related (<15 SNPs) S. aureus or S. pseudintermedius were found in humans or dogs in three households. About 56.3% S. aureus carriers (dog or human) harboured diverse within-host spa-types or AMR genotypes. Ten clonal complexes (CCs) were detected among the S. aureus, of which methicillin-susceptible S. aureus-CC398-IEC-type C (t1451 and t571) was the most frequent, but exclusive to humans. S. aureus and S. pseudintermedius isolates harboured resistance genes or mutations associated to 9 classes of antimicrobials including linezolid (G2261A & T1584A point mutations in 23S rDNA). The S. coagulans isolates were susceptible to all antimicrobials. Most of the S. pseudintermedius carried lukS/F-I, siet, and sient genes, and all S. aureus were negative for lukS/F-PV, tst-1, eta and etb genes.

Discussion

Clonally related human-to-human MSSA and dog-to-human MSSP were found. The detection of the MSSA-CC398 clade highlights the need for its continuous surveillance from One Health perspective.

Nasal Staphylococcus aureus and S. pseudintermedius carriage in healthy dogs and cats: a systematic review of their antibiotic resistance, virulence and genetic lineages of zoonotic relevance

The molecular ecology of Staphylococcus aureus, Staphylococcus pseudintermedius and their methicillin-resistant strains in healthy dogs and cats could serve as good models to understand the concept of bacterial zoonosis due to animal companionship. This study aims to provide insights into pooled prevalence, genetic lineages, virulence and antimicrobial resistance (AMR) among healthy dogs and cats. Original research and brief communication articles published from 2001 to 2021 that reported the nasal detection of S. aureus and S. pseudintermedius in healthy dogs and cats in the community, homes and outside veterinary clinics were examined and analysed. Forty-nine studies were eligible and included in this systematic review. The pooled prevalence of nasal carriage of S. aureus/methicillin-resistant S. aureus (MRSA) in healthy dogs and cats were 10.9% (95% CI: 10.1-11.9)/2.8% (95% CI: 2.4-3.2) and 3.2% (95% CI: 1.9-4.8)/0.5% (95% CI: 0.0-1.1), respectively. Conversely, the pooled prevalence of S. pseudintermedius/methicillin-resistant S. pseudintermedius (MRSP) in healthy dogs and cats were 18.3% (95% CI: 17.1-19.7)/3.1% (95% CI: 2.5-3.7) and 1.3% (95% CI: 0.6-2.4)/1.2% (95% CI: 0.6-2.3), respectively. Although highly diverse genetic lineages of S. aureus were detected in healthy dogs and cats, MSSA-CC1/CC5/CC22/CC45/CC121/CC398 and MRSA-CC5/CC93/CC22/CC30 were mostly reported in dogs; and MSSA-CC5/CC8/CC15/CC48 and MRSA-CC22/CC30/CC80 in cats. Of note, MSSA-CC398 isolates (spa-types t034 and t5883) were detected in dogs. Genetic lineages often associated with MSSP/MRSP were ST20/ST71, highlighting the frequent detection of the epidemic European MRSP-ST71 clone in dogs. S. aureus isolates carrying the luk-S/F-PV, tst, eta, etb and etd genes were seldomly detected in dogs, and luk-S/F-PV was the unique virulence factor reported in isolates of cats. S. pseudintermedius isolates harbouring the luk-S/F-I, seint and expA genes were frequently found, especially in dogs. High and diverse rates of AMR were noted, especially among MRSA/MRSP isolates. There is a need for additional studies on the molecular characterization of isolates from countries with under-studied nasal staphylococci isolates.

Screening of Toxin Genes in Methicillin-Resistant Staphylococcus aureus Clinical Isolates from a Hospital Setting in a Tertiary Hospital in Northern Cyprus

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant opportunistic pathogen with a wide repertoire of virulence characteristics. Data regarding the molecular profile of MRSA in Northern Cyprus is limited. The current study aimed to examine the virulence profiles of MRSA with a focus on toxin-associated factors. Ninety-one S. aureus isolates collected at a university hospital were included in the study. Identification and antibiotic susceptibility testing were performed with BD Phoenix™ automated system. Methicillin resistance was evaluated by the disc diffusion assay and mecA detection. The presence of nuc was confirmed by conventional PCR. Confirmed MRSA isolates were assessed for the presence of virulence genes hla, eta, etb, etd and tst using molecular methods. Among 91 S. aureus isolates identified as MRSA using the BD Phoenix™ platform, 80.85% (n = 76/91) were confirmed as MRSA using phenotypic and genotypic methods. All confirmed MRSA isolates (n = 76, 100%) were positive for the nuc. MRSA rates were statistically higher in elderly inpatients. The prevalence of toxin-encoding genes was 97.3% (n = 74/76) for hla, 2.63% (n = 2/76) for eta, 1.3% (n = 1/76) for etb, and 2.63% (n = 2/76) for tst. None of the screened isolates harbored the etd gene. These results represent the first report to investigate multiple virulence factors in MRSA isolates in Northern Cyprus.

Cheminformatics Identification of Phenolics as Modulators of Penicillin-Binding Protein 2a of Staphylococcus aureus: A Structure–Activity-Relationship-Based Study

The acquisition of penicillin-binding protein (PBP) 2a in resistant strains of Staphylococcus aureus allows for the continuous production of cell walls even after the inactivation of intrinsic PBPs. Thus, the discovery of novel therapeutics with enhanced modulatory activity on PBP2a is crucial, and plant secondary metabolites, such as phenolics, have found relevance in this regard. In this study, using computational techniques, phenolics were screened against the active site of PBP2a, and the ability of the lead phenolics to modulate PBP2a’s active and allosteric sites was studied. The top-five phenolics (leads) identified through structure–activity-based screening, pharmacokinetics and synthetic feasibility evaluations were subjected to molecular dynamics simulations. Except for propan-2-one at the active site, the leads had a higher binding free energy at both the active and allosteric sites of PBP2a than amoxicillin. The leads, while promoting the thermodynamic stability of PBP2a, showed a more promising affinity at the allosteric site than the active site, with silicristin (−25.61 kcal/mol) and epicatechin gallate (−47.65 kcal/mol) having the best affinity at the active and allosteric sites, respectively. Interestingly, the modulation of Tyr446, the active site gatekeeper residue in PBP2a, was noted to correlate with the affinity of the leads at the allosteric site. Overall, these observations point to the leads’ ability to inhibit PBP2a, either directly or through allosteric modulation with conventional drugs. Further confirmatory in vitro studies on the leads are underway.

Antibiotic susceptibility pattern of canine coagulase positive and coagulase negative Staphylococcus spp. in a hot and dry region of India

The emergence of anti microbial resistance among Staphylococcus spp. isolated from clinical cases of canines should be continuously monitored hence the present study was formulated to ascertain the antibiotypes and methicillin resistance in coagulase positive and coagulase negative staphylococci of canine skin and associated mucous membrane affections from a hot and dry region of India. A total of 165 clinical samples were collected and Staphylococcus aureus was identified by conventional bacteriological methods and PCR. Antibiotic susceptibility test was done against commercially available antibiotic impregnated discs as per Clinical and Laboratory Standards Institute (CLSI) method. Methicillin resistance was determined by plate methods and then via PCR of mecA gene. These 165 samples yielded, 88 (53.33%) isolates of genus Staphylococcus and 46 Staphylococcus aureus and 51/88 (57.95%) isolates were coagulase positive staphylococci. Total 55 (62.5%) isolates showed susceptibility to Ceftriaxone/Sulbactum, 37 (42.05%) to Ciprofloxacin, 26 (29.55 %) to Oxacillin, 24 (27.27 %) to Penicillin, and 10 (11.36 %) to Gentamicin. Total 21 methicillin resistant Staphylococcus aureus (MRSA) and 12 methicillin resistant coagulase negative staphylococci (MRCoNS) were found on phenotypic basis whereas the mecA gene was detected in 6 /21 MRSA and 2 /12 MRCoNS isolates. Staphylococcus spp. showed increased level of resistance against commonly used antibiotics. The higher prevalence of methicillin resistance found with phenotypic methods than to mecA PCR indicates towards additional mechanisms responsible for emergence of MRS, especially in CoNS.

Tracking Infection and Genetic Divergence of Methicillin-Resistant Staphylococcus aureus at Pets, Pet Owners, and Environment Interface

Staphylococcus aureus (S. aureus) has become a leading animal and public health pathogen that keeps on transferring from one host to other, giving rise to newer strains by genetic shifts. The current study was designed to investigate the epidemiology and genetic relatedness of mecA gene in S. aureus isolated from pets, immediate individuals in contact with pets, and veterinary clinic environments. A total of n = 300 samples were collected from different veterinary hospitals in Pakistan using convenience sampling. The collected samples were subjected to microbiological and biochemical examination for the isolation of S. aureus. Methicillin resistance was investigated by both phenotypically using oxacillin disk diffusion assay and by genotypically targeting mecA gene by PCR. PCR amplicons were subjected for sequencing by Sanger method of sequencing, which were subsequently submitted to NCBI GenBank under the accession numbers MT874770, MT874771, and MT874772. Sequence evolutionary analysis and mecA gene characterization was done using various bioinformatics tools. Overall, 33.66% mecA genes harboring S. aureus strains were isolated from all sources (33.33% from pets, 46.0% from surrounding, and 28.0% from immediate contact individuals). The bioinformatics analysis noted that one SNP was identified at position c.253C>A (Transvertion). The phylogenetic tree (two clades) of S. aureus mecA revealed a possibility of inter-transmission of disease between the environment and pets. Frequency of adenine and thymine nucleotide in motifs were found to be the same (0.334). Cytosine and guanine frequency were also the same (0.166). Threonine was replaced by asparagine (p.T84D) in each sample of cat, environment, and human. On the other hand, protein structures ofcat-1 and cat-2 proteins were found identical while cat-3, environmental, and human proteins shared identical structures. The study thus concludes rising circulation of methicillin-resistant S. aureus (MRSA) strains in animal-human-environment interfaces, forecasting the development of novel strains withmodified range of resistance.

Occurrence and Antibiotic Resistance Profiles of Methicillin-Resistant Staphylococcus Aureus (Mrsa) in Layer Chickens in Kebbi, Nigeria

Antimicrobial resistance (AMR) is a global health threat, and antimicrobial use in animal production for growth enhancement or prophylaxis contributes to the development of AMR. A cross-sectional study was conducted to investigate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in poultry and farm attendants in Kebbi, North-Western Nigeria. A total of 207 cloacal and nasal swabs were randomly collected from four farms comprising 50 samples from each poultry farm and only 7 samples from farm attendants. The samples were analysed using routine bacteriological culture and identification techniques. Presumptive MRSA isolates were confirmed by PCR assay and AMR profiles of the isolates were evaluated using the Kirby-Bauer disk diffusion method. Of the 207 samples examined, 37.5 % (75/200) of layer birds tested positive for MRSA and 71.4 % (5/7) of farm attendants were MRSA positive. All the isolates were susceptible to vancomycin, with an AMR index ˃ 0.3. The findings of this study indicated colonization of layer chickens and humans by multidrug resistant MRSA, thus highlighting the potential role of poultry sources of transmission of multidrug-resistant MRSA strains to humans and vice versa.

Characterization and antimicrobial susceptibility of coagulase-positive Staphylococcus isolated in a veterinary teaching hospital in Chile

There is limited information about the prevalence and antimicrobial susceptibility of coagulase-positive Staphylococcus (CoPS) strains in veterinary settings in Chile. The aim of this observational study was to identify and characterize CoPS strains from dogs, owners, veterinary professionals and surfaces in a veterinary teaching hospital at Universidad de Chile to determine the presence of methicillin-resistant strains and evaluate the genetic relationship among the strains. Veterinarians (n=24), surfaces (n=10), and healthy dogs (n=40) and their respective owners (n=40) were sampled for CoPS. Isolates were identified by PCR and antimicrobial susceptibility was assessed by the disk diffusion method and MIC. The presence of the mecA gene was evaluated by PCR, and the genetic relationship among the strains was established by PFGE. A total of 45 CoPS strains were obtained, eight from veterinary professionals, three from hospital surfaces, eight from owners and 26 from dogs. Nine of the strains were resistant to methicillin (20%), and all of them carried the mecA gene. A high percentage of the strains was resistant to clindamycin (33.3%). Additionally, the isolated CoPS showed high genetic diversity. This study suggests that veterinarians are in high risk of harboring methicillin-resistant CoPS (25% versus 2.5% from owners) and our results provide evidence that clindamycin could not be an empiric alternative for CoPS in the analyzed hospital. This is the first report of methicillin-resistant CoPS in veterinary settings in Chile, considering humans, pets and surfaces.

Lacticaseibacillus spp.; Probiotic candidates from Palmyra palm sugar, possess antimicrobial, and anti-biofilm activities against methicillin-resistant Staphylococcus aureus

Background and Aim: Probiotics are beneficial microorganisms that play important roles by adhering to the gut and producing antimicrobial substances to inhibit pathogens. The objective of this study was to isolate and characterize the probiotic lactic acid bacteria (LAB) from Palmyra palm sugar, which can produce antimicrobial compounds against methicillin-resistant Staphylococcus aureus (MRSA), a new zoonotic and food-borne pathogens. Materials and Methods: Twenty-six LAB isolates were isolated from 30 Palmyra palm sugar samples. Three selected LAB were further characterized as probiotics. In addition, the antibacterial and anti-biofilm-forming activities of the probiotics' culture supernatants against MRSA and food-borne pathogens were investigated. Finally, the selected probiotics were identified by aligning 16S rRNA sequences. Results: The three confirmed probiotics, WU 0904, WU 2302, and WU 2503, showed strong antibacterial activities against S. aureus, MRSA, Escherichia coli O157:H7, and Listeria monocytogenes, as measured by a broth microdilution assay. Among the LAB isolates, 82.22-86.58%, 91.83-96.06%, and 64.35-74.93% exhibited resistance to low pH, pancreatin treatment, and bile salts, respectively. It was found that 59.46% and 83.33% auto-aggregation was observed in 2 and 24 h, respectively. Moreover, 50.25-57.24% adhesion was detected after the incubation of the bacterial cells to Caco-2 cells. . Biofilm inhibition (82.81-87.24%) was detected after the treatment of MRSA with the culture supernatants, when compared with that to the control. By the alignment of 16S rRNA sequences, the isolate WU 2302 was identified as Lacticaseibacillus spp. with 98.82% homology when compared to the GenBank database. Conclusion: This study indicates that isolated probiotics can produce antimicrobial compounds against MRSA and food-borne pathogens. The obtained results strongly suggest that these probiotics are promising candidates for pharmaceutical products.

Molecular detection of vancomycin and methicillin resistance in Staphylococcus aureus isolated from food processing environments

Staphylococcus aureus is a well-known foodborne pathogen. The aim of this study was to investigate the presence of S. aureus isolated from serving utensils in food processing environments in Mymensingh city, Bangladesh and to determine their antibiogram and resistance determinants. A total of 120 environmental samples were collected from different food settings. Isolation and identification were conducted using conventional biochemical tests. Molecular identification of isolates and detection of methicillin and vancomycin resistance were done using primer-specific polymerase chain reaction (PCR) targeting Tuf, nuc, mecA, and mecC genes. Antibiotic sensitivity tests were performed, and resistance genes were also detected by amplifying bla TEM , vanA, vanB, and vanC genes. Among the 120 samples, 81 (67.5%) were positive for Staphylococcus spp. and 41 (50.62%) were positive for the nuc-gene. Among the 41 isolates, 5 (12.20%) were positive for mecA, but none were positive for the mecC gene. A total of 12.2% of the isolates were vanC-positive, of which 4 isolates (9.76%) were also positive for the mecA gene. Antibiotic sensitivity testing revealed that all S. aureus isolates (100%) from hotel samples were sensitive to ciprofloxacin and chloramphenicol, 90.32% were sensitive to doxycycline, and 80.65% were sensitive to streptomycin. Conversely, all isolates (100%) were resistant to ampicillin, and 29.03% were resistant to vancomycin. All S. aureus isolates obtained from non-hotel samples were susceptible to chloramphenicol, ceftriaxone, ciprofloxacin, doxycycline, meropenem, and vancomycin; however, 40% of isolates were resistant to novobiocin. Among the hotel isolates, 29 (93.55%) of the ampicillin-resistant isolates harbored the blaTEM gene while 5 (55.55%) of the vancomycin-resistant isolates harbored the vanC gene. Four of the five vanC positive isolates were also positive for the mecA gene. The presence of methicillin-resistant S. aureus (MRSA) which is also vancomycin-resistant in food processing environments is a threat to public health. This is the first report on the molecular detection of methicillin and vancomycin-resistant S. aureus isolated from food processing environments in Bangladesh.

Efficacy of dalbavancin against MRSA biofilms in a rat model of orthopaedic implant-associated infection

OBJECTIVES

The aim of this study was to evaluate the efficacy of dalbavancin against MRSA biofilm-related infection in orthopaedic implants in vivo.

METHODS

One MRSA strain isolated from human osteomyelitis was used to promote biofilm formation on the surface of screws. The implants were inserted in the proximal tibia under general anaesthesia. Thirty-nine Wistar rats were divided into three groups [control group (no treatment), Group 1 (7 days of treatment) and Group 2 (14 days of treatment)]; both treatment groups were administered dalbavancin intraperitoneally and euthanized after treatment. cfu of bacteria present in both the tibia and the implant were quantified. The infection severity was assessed by histopathology and scored from 0 (no infection) to 4 (severe infection).

RESULTS

The high number of cfu/g and cfu/mL present in the control group indicated a well-established infection. There was a significant reduction in cfu in rats treated with dalbavancin both in the tibia (2.8 × 105 cfu/g) and the implant (1.1 × 106 cfu/mL) in Group 1 (1.8 × 103 cfu/g and 2.4 × 105 cfu/mL, respectively) and in Group 2 (8.2 cfu/g and 8.2 × 103 cfu/mL, respectively). Most animals from the control group presented an infection scored as 3 (severe). At the end of the experiment, most rats from Groups 1 and 2 presented an infection scored as 2 (moderate) and 0 (no infection), respectively.

CONCLUSIONS

Although there was a marked decrease in cfu number, signs of biofilm-induced infection prevailed after 14 days of treatment. Further studies should be carried out to evaluate the potential of dalbavancin in the treatment of bone and orthopaedic implant-associated MRSA infections.

Nasopharyngeal Carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) among Sickle Cell Disease (SCD) Children in the Pneumococcal Conjugate Vaccine Era

The aim of this cross-sectional study was to investigate Staphylococcus aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into pneumococcal conjugate vaccine 13 (PCV-13) introduction in Ghana. The study involved bacteriological culture of nasopharyngeal swabs obtained from 202 SCD children recruited from the Princess Marie Louise Children's Hospital. S. aureus isolates were identified using standard methods and subjected to antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Cefoxitin-resistant S. aureus isolates were screened for carriage of the mecA, pvl, and tsst-1 genes using multiplex polymerase chain reaction. The carriage prevalence of S. aureus was 57.9% (n = 117), and that of methicillin-resistant S. aureus (MRSA) was 3.5% (n = 7). Carriage of the mecA, pvl, and tsst-1 genes were respectively demonstrated in 20.0% (n = 7), 85.7% (n = 30), and 11.4% (n = 4) of the cefoxitin-resistant S. aureus isolates. PCV-13 vaccination (OR = 0.356, p = 0.004) and colonization with coagulase-negative staphylococci (CoNS) (OR = 0.044, p < 0.0001) each protected against S. aureus carriage. However, none of these and other features of the participants emerged as a determinant of MRSA carriage. The following antimicrobial resistance rates were observed in MRSA compared to methicillin-sensitive S. aureus: clindamycin (28.6% vs. 4.3%), erythromycin (42.9% vs. 19.1%), tetracycline (100% vs. 42.6%), teicoplanin (14.3% vs. 2.6%), penicillin (100% vs. 99.1%), amoxiclav (28.6% vs. 3.5%), linezolid (14.3% vs. 0.0%), ciprofloxacin (42.9% vs. 13.9%), and gentamicin (42.9% vs. 13.0%). The proportion of S. aureus isolates that were multidrug resistant was 37.7% (n = 46). We conclude that S. aureus was the predominant colonizer of the nasopharynx of the SCD children, warranting the continuous monitoring of this risk group for invasive S. aureus infections.

Acquisition and carriage of multidrug-resistant organisms in dogs and cats presented to small animal practices and clinics in Switzerland

BACKGROUND

The emergence and spread of multidrug-resistant organisms (MDRO) present a threat to human and animal health.

OBJECTIVES

To assess acquisition, prevalence of and risk factors for MDRO carriage in dogs and cats presented to veterinary clinics or practices in Switzerland.

ANIMALS

Privately owned dogs (n = 183) and cats (n = 88) presented to 4 veterinary hospitals and 1 practice.

METHODS

Prospective, longitudinal, observational study. Oronasal and rectal swabs were collected at presentation and 69% of animals were sampled again at discharge. Methicillin-resistant (MR) staphylococci and macrococci, cephalosporinase-, and carbapenemase-producing (CP) Enterobacterales were isolated. Genetic relatedness of isolates was assessed by repetitive sequence-based polymerase chain reaction and multilocus sequence typing. Risk factors for MDRO acquisition and carriage were analyzed based on questionnaire-derived and hospitalization data.

RESULTS

Admission prevalence of MDRO carriage in pets was 15.5% (95% confidence interval [CI], 11.4-20.4). The discharge prevalence and acquisition rates were 32.1% (95% CI, 25.5-39.3) and 28.3% (95% CI, 22-35.4), respectively. Predominant hospital-acquired isolates were extended spectrum β-lactamase-producing Escherichia coli (ESBL-E coli; 17.3%) and β-lactamase-producing Klebsiella pneumoniae (13.7%). At 1 institution, a cluster of 24 highly genetically related CP (bla_oxa181 and bla_oxa48 ) was identified. Multivariate analysis identified hospitalization at clinic 1 (odds ratio [OR], 5.1; 95% CI, 1.6-16.8) and days of hospitalization (OR 3-5 days, 4.4; 95% CI, 1.8-10.9; OR > 5 days, 6.2; 95% CI, 1.3-28.8) as risk factors for MDRO acquisition in dogs.

CONCLUSIONS

Veterinary hospitals play an important role in the selection and transmission of MDRO among veterinary patients.

First report of oxacillin-susceptible mecA-positive Staphylococcus aureus in healthy dogs and their owners in southern Brazil

Oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) isolates have been described worldwide, but data regarding dogs and their owners have not been reported. This study investigated the occurrence of OS-MRSA and MRSA isolates in the nasal mucosa of 241 healthy dogs and 208 owners in the community. S. aureus isolates were characterized by susceptibility testing, detection of the mecA and the Panton-Valentine leukocidin (PVL) genes, staphylococcal chromosome cassette (SCC)mec typing and rep-PCR-RW3A. We report an unprecedented detection of nasal carriage of OS-MRSA in 5.3 % (2/38) of healthy dogs and 1.75 % (1/57) of their owners. We also found MRSA in 2.6 % (1/38) of the dogs and 3.5 % (2/57) of the owners. Only the human isolate was SCCmec IV and PVL-positive. Molecular typing revealed that the same cluster of S. aureus was present in owners and dogs from the same or different families attended at the same veterinary clinic. The three OS-MRSA isolates did not show genetic similarity to each other. Detection of OS-MRSA in this context alerts us to the role of dogs and owners as possible silent reservoirs of this microorganism in the community, which may potentially be misidentified as methicillin-sensitive S. aureus (MSSA) in the laboratory routine, representing an additional threat in antimicrobial therapy for staphylococcal infections.

Prevalence of Panton-Valentine leukocidin in methicillin-resistant Staphylococcus aureus clinical isolates at a university hospital in Northern Cyprus: a pilot study

Objective

Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) is a healthcare problem worldwide. There are no reports on the virulence characteristics of MRSA in Northern Cyprus (NC). This study aimed to determine the presence of pvl among MRSA isolates from patients admitted to a university hospital in NC using molecular methods. Fifty S. aureus strains were included in this study. BD Phoenix automated identification system was used for bacterial identification and antibiotic susceptibility testing. Methicillin resistance was confirmed by disc diffusion assay. Presence of nuc and mecA genes was tested by multiplex PCR. Detection of pvl gene was performed by single-target PCR.

Results

Out of 50 S. aureus isolates identified as MRSA by BD Phoenix system, 3 were susceptible to cefoxitin with disc diffusion assay and were confirmed as methicillin-sensitive S. aureus (MSSA). All isolates (n = 50, 100%) tested positive for the presence nuc gene and 68% (n = 34/50) were mecA positive. pvl was detected in 27.7% (n = 13/47) of the MRSA isolates. Among PVL-positive MRSA isolates, 69.2% (9/13) were inpatients. PVL-MRSA was more common in isolates from deep tracheal aspirate (30.8%, 4/13) and abscess/wound (23.1%, 3/13). This represents the first study of PVL presence among MRSA in hospital setting in NC.

Antimicrobial Resistance and Virulence of Methicillin-Resistant Staphylococcus aureus from Human, Chicken and Environmental Samples within Live Bird Markets in Three Nigerian Cities

Background: Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major threat to public health. This study investigated the occurrence of MRSA in humans, chickens, chicken meat and environmental samples within poultry farms and live bird markets in southwestern Nigeria. Methods: MRSA were isolated using selective culture and tested for antimicrobial susceptibility by broth microdilution. Selected isolates were characterized by whole genome sequencing (WGS). From WGS data, spa, dru, multilocus sequence typing (MLST) and SCCmec types, but also virulence and antimicrobial resistance genes, were identified. Results: Fifty-six MRSA isolates were detected in 734 samples. They showed resistance to β-lactams (100%), tetracycline (60.7%), ciprofloxacin (33.9%), erythromycin (28.6%), gentamicin (32.1%), and trimethoprim/sulfamethoxazole (10.7%). All 30 isolates investigated by WGS carried mecA, dfrG, and tet(38) genes. Other resistance genes detected were blaZ (83.3%), fosB (73.3%), tet(K) (60.0%), aacA-aphD (36.6%), aphA3 (33.3%), msr(A) (30.0%), mph(C) (30.0%), dfrS1 (3.3%), and sat4 (3.3%). Seven spa types (t091, t314, t657, t1476, t2331, t4690 and t12236), four known (dt9aw, dt10ao, dt10cj, and dt11a) and two novel (dt10dr and dt11dw) dru types, as well as five sequence types (ST8, ST121, ST152, ST772 and ST789) were found among the MRSA isolates. All ST121 isolates carried an SCCmec type IV cassette and were not dru-typeable. ST152 and ST121 were found only in specific sample categories within defined locations, while ST8 and ST772 were distributed across most sample categories and locations. Three SCCmec types, IVa, V and Vc, were identified. All MRSA isolates possessed virulence genes including aur, clpP, coa, fnbA, esaA, hly, hla, ica, isdA, srtB, sspA, and vWbp, among others. The toxic shock syndrome toxin gene (tst) was not detected in any isolate, whereas the Pantone-Valentine leukocidin genes lukF-PV/lukS-PV were present in all ST121, all ST772, and all but one ST152 isolates. Conclusion: The results of this study (i) showed that chicken meat is contaminated by MRSA and (ii) suggested that live bird markets may serve as focal points for the dissemination of MRSA within the community.

Antimicrobial resistance pattern in domestic animal - wildlife - environmental niche via the food chain to humans with a Bangladesh perspective; a systematic review

BACKGROUND

Antimicrobial resistance (AMR) is a growing concern globally, but the impact is very deleterious in the context of Bangladesh. Recent review article on the AMR issue demonstrates the scenario in human medicine; unfortunately, no attempt was taken to address this as One Health issue. The antimicrobial resistance bacteria or genes are circulating in the fragile ecosystems and disseminate into human food chain through direct or indirect ways. In this systematic review we are exploring the mechanism or the process of development of resistance pathogen into human food chain via the domestic animal, wildlife and environmental sources in the context of One Health and future recommendation to mitigate this issue in Bangladesh.

RESULTS

Tetracycline resistance genes were presenting in almost all sample sources in higher concentrations against enteric pathogen Escherichia coli. The second most significant antibiotics are amino-penicillin that showed resistant pattern across different source of samples. It is a matter of concerns that cephalosporin tends to acquire resistance in wildlife species that might be an indication of this antibiotic resistance gene or the pathogen been circulating in our surrounding environment though the mechanism is still unclear.

CONCLUSIONS

Steps to control antibiotic release and environmental disposal from all uses should be immediate and obligatory. There is a need for detailed system biology analysis of resistance development in-situ.

Systematic Review and Meta-Analysis of the Occurrence of ESKAPE Bacteria Group in Dogs, and the Related Zoonotic Risk in Animal-Assisted Therapy, and in Animal-Assisted Activity in the Health Context

Animal-assisted interventions are widely implemented in different contexts worldwide. Particularly, animal-assisted therapies and animal-assisted activities are often implemented in hospitals, rehabilitation centers, and other health facilities. These interventions bring several benefits to patients but can also expose them to the risk of infection with potentially zoonotic agents. The dog is the main animal species involved used in these interventions. Therefore, we aimed at collecting data regarding the occurrence of the pathogens ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) in dogs, in order to draft guidelines concerning the possible monitoring of dogs involved in animal-assisted therapies and animal-assisted activities in healthcare facilities. We performed a literature search using the PRISMA guidelines to examine three databases: PubMed, Web of Science, and Scopus. Out of 2604 records found, 52 papers were identified as eligible for inclusion in the review/meta-analysis. Sixteen papers reported data on E. faecium; 16 on S. aureus; nine on K. pneumoniae; four on A. baumannii; eight on P. aeruginosa; and six on Enterobacter spp. This work will contribute to increased awareness to the potential zoonotic risks posed by the involvement of dogs in animal-assisted therapies, and animal-assisted activities in healthcare facilities.

Detection of antibiotic-resistant bacteria and their resistance genes from houseflies

Background and Aim:

Houseflies (Musca domestica) are synanthropic insects which serve as biological or mechanical vectors for spreading multidrug-resistant bacteria responsible for many infectious diseases. This study aimed to detect antibiotic-resistant bacteria from houseflies, and to examine their resistance genes.

Materials and Methods:

A total of 140 houseflies were captured using sterile nylon net from seven places of Mymensingh city, Bangladesh. Immediately after collection, flies were transferred to a sterile zipper bag and brought to microbiology laboratory within 1 h. Three bacterial species were isolated from houseflies, based on cultural and molecular tests. After that, the isolates were subjected to antimicrobial susceptibility testing against commonly used antibiotics, by the disk diffusion method. Finally, the detection of antibiotic resistance genes tetA, tetB, mcr-3, mecA, and mecC was performed by a polymerase chain reaction.

Results:

The most common isolates were Staphylococcus aureus (78.6%), Salmonella spp., (66.4%), and Escherichia coli (51.4%). These species of bacteria were recovered from 78.3% of isolates from the Mymensingh Medical College Hospital areas. Most of the isolates of the three bacterial species were resistant to erythromycin, tetracycline, penicillin and amoxicillin and were sensitive to ciprofloxacin, ceftriaxone, chloramphenicol, gentamicin, and azithromycin. Five antibiotic resistance genes of three bacteria were detected: tetA, tetB, mcr-3, and mecA were found in 37%, 20%, 20%, and 14% isolates, respectively, and no isolates were positive for mecC gene.

Conclusion:

S. aureus, Salmonella spp., and E. coli with genetically-mediated multiple antibiotic resistance are carried in houseflies in the Mymensingh region. Flies may, therefore, represent an important means of transmission of these antibiotic-resistant bacteria, with consequent risks to human and animal health.

Occurrence of multidrug-resistant methicillin-resistant Staphylococcus aureus among healthy farm animals: a public health concern

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging pathogen causing serious public health threats. This study was conducted to investigate the occurrence of multidrug-resistant MRSA among apparently healthy farm animals to shed the light on the potential role of these animals as a reservoir for such pathogen. For this purpose, 195 nasal swabs from apparently healthy farm animals (52 sheep, 51 goats, 47 cattle and 45 buffalo) were screened for multidrug-resistant MRSA. MRSA was isolated using a selective chromogenic medium and identified by colonial characters, Gram’s stain films, conventional biochemical tests, coagulase test, resistance to cefoxitin and amplification of nuc and mecA genes. The antimicrobial susceptibility testing profile was performed by disk diffusion method to identify multidrug-resistant MRSA. Of 195 samples, 7 yielded MRSA with an overall prevalence 3.6%, whereas the prevalence rates were 3.8%, 3.9%, 4.3% and 2.2% for sheep, goats, cattle and buffalo, respectively. All MRSA isolates were multidrug-resistant strains. The phylogenetic analysis of 2 mecA gene sequences from the obtained isolates revealed that both sequences were clustered in the same clade with those derived from human clinical cases from different countries to highlight the public health burden of such strains. The distribution of multidrug-resistant MRSA among all examined farm animal species being apparently healthy points out that farm animals could represent a potential reservoir for multidrug-resistant MRSA with public health implications.

Antimicrobial Activity of Divaricatic Acid Isolated from the Lichen Evernia mesomorpha against Methicillin-Resistant Staphylococcus aureus

One hundred and seventy seven acetone extracts of lichen and 258 ethyl acetate extracts of cultured lichen-forming fungi (LFF) were screened for antimicrobial activity against Staphylococcus aureus and Enterococcus faecium using a disk diffusion method. Divaricatic acid was isolated from Evernia mesomorpha and identified by LC-MS, ¹H-, ¹³C- and DEPT-NMR. Purified divaricatic acid was effective against Gram + bacteria, such as Bacillus subtilis, Staphylococcus epidermidis, Streptococcus mutans, and Enterococcus faecium, with the minimum inhibitory concentration (MIC) values ranging from 7.0 to 64.0 μg/mL, whereas vancomycin was effective in the MICs ranging from 0.78 to 25.0 μg/mL. Interestingly, the antibacterial activity of divaricatic acid was higher than vancomycin against S. epidermidis and E. faecium, and divaricatic acid was active against Candida albicans. In addition, divaricatic acid was active as vancomycin against S. aureus (3A048; an MRSA). These results suggested that divaricatic acid is a potential antimicrobial agent for the treatment of MRSA infections.