Staphylococcus simulans associated with endocarditis in broiler chickens

Case reports involving coinfection with Avibacterium paragallinarum and Ornithobacterium rhinotracheale in broiler chickens and Avibacterium endocarditis in broiler breeding hens in Poland

ABSTRACTThe study describes three clinical cases of infection with Avibacterium spp.. In case no. 1, respiratory clinical signs and high mortality (0.7-4.2% daily; total 21.2%) in Ross 308 broiler chickens were shown to be caused by coinfection with sequence type 9 of O. rhinotracheale presumptive serotype A and A. paragallinarum presumptive serotype B. The identical (pulsed-field gel electrophoresis) restriction pattern (pulsotype) of seven A. paragallinarum isolates indicated that infectious coryza in broilers was caused by the same clone. In cases 2 and 3, sudden increased deaths in Ross 308 broiler breeders (especially males) with lesions in the endocardium (valvular or mural endocarditis) were shown to be caused by A. endocarditis. Among nine antibiotics tested, florfenicol was the only antibiotic to which all A. paragallinarum and O. rhinotracheale isolates were susceptible. Out of the eight antibiotics tested, 11 A. endocarditis isolates from both clinical cases of infective endocarditis were susceptible to penicillin, amoxicillin, doxycycline and florfenicol. The A. endocarditis isolates tested in both clinical cases had different PFGE patterns (pulsotypes), but identical within a case. The causes of infectious coryza and infective endocarditis in the cases presented have not been determined. In the prevention of infectious diseases in large-scale livestock farming, it is very important to follow the rules of biosecurity.

Coagulase-negative staphylococci are the main causes of bacterial meningitis in duck

Since September 2018, serious meningitis has been found on some breeding-duck farms in Shandong Province, China. A large number of ducks exhibit severe neurological symptoms. The ducks were randomly selected for laboratory testing. Duck brain samples were collected using standard sterile techniques, and the staphylococci isolates were detected in 404 (70.14%) out of 576 brain samples. A total of 525 coagulase-negative staphylococci (CoNS) strains were isolated, including 6 species: Staphylococcus sciuri (S. sciuri) (67.24%, 353/525), Staphylococcus epidermidis (S. epidermidis) (9.71%, 51/525), Staphylococcus saprophyticus (S. saprophyticus) (8.38%, 44/525), Staphylococcus lentus (S. lentus) (7.62%, 40/525), Staphylococcus haemolyticus (S. haemolyticus) (2.48%, 13/525), and Staphylococcus xylosus (S. xylosus) (4.57%, 24/525). Mixed strain infections were detected in 121 (29.95%) infected presentations. The antimicrobial susceptibility testing indicated that 40.38% of the isolates exhibited multi-drug resistance, and 53.90% of the strains were methicillin-resistant strains by amplification of the methicillin resistance gene (mecA) gene. Through experimental reproduction of the disease, we determined that the CoNS strains were the leading pathogens causing bacterial meningitis in ducks. Although these CoNS strains does not directly cause the death of sick ducks, they still cause large economic losses due to the retarded growth and development of the sick ducks, lower feed returns, and lower grades of processed duck products. The results of this study will contribute to our understanding of the epidemiology and pathogenesis of CoNS and be helpful in the prevention and treatment of the infection.

Characterization and pathogenicity of multidrug-resistant coagulase-negative Staphylococci isolates in chickens

The pathogenic potential of vancomycin and methicillin-resistant coagulase-negative Staphylococci (VMRCoNS) on Egyptian poultry farms has received little attention. Therefore, this study aims to study the prevalence of CoNS in imported poultry flocks and commercial poultry farms, evaluate the presence of virulence and antibiotic resistance genes (sea, seb, sec, sed, see, and mecA), and assess their pathogenicity in broiler chicks. Seven species were identified among 25 isolates, such as 8 S. gallinarum, 5 S. saprophyticus, 5 S. chromogens, 3 S. warneri, 2 S. hominis, 1 S. caprae, and 1 S. epidermidis. All isolates were resistant to clindamycin, doxycycline, vancomycin, methicillin, rifampicin, and penicillin. The mecA gene was confirmed in 14 isolates, while the sed gene was revealed in seven isolates. Commercial 1-day-old Ross broiler chicks were divided into eight groups of three replicates (10 birds/group): group Ӏ was negative control; groups (П, Ш, IV, V, VI, VII, and VIII) were subcutaneously inoculated with 108 CFUml-1 of S. hominis, S. caprae, S. epidermidis, S. gallinarum, S. chromogens, S. warneri, and S. saprophyticus, respectively. Groups VIII and V had mortality rates of 100% and 20%, respectively, with no evidence of mortalities in the other groups. The highest re-isolation of CoNS species was recorded in groups VII, VIII, and V. Postmortem and histopathological examination revealed the common presence of polyserositis in the internal organs, and hepatic and myocardial necrosis in groups IV, V, and VI. These findings revealed the pathogenic potential of CoNS, so special attention must be directed toward their public health impact.

Farming Practice Influences Antimicrobial Resistance Burden of Non-Aureus Staphylococci in Pig Husbandries

Non-aureus staphylococci (NAS) are ubiquitous bacteria in livestock-associated environments where they may act as reservoirs of antimicrobial resistance (AMR) genes for pathogens such as Staphylococcus aureus. Here, we tested whether housing conditions in pig farms could influence the overall AMR-NAS burden. Two hundred and forty porcine commensal and environmental NAS isolates from three different farm types (conventional, alternative, and organic) were tested for phenotypic antimicrobial susceptibility and subjected to whole genome sequencing. Genomic data were analysed regarding species identity and AMR gene carriage. Seventeen different NAS species were identified across all farm types. In contrast to conventional farms, no AMR genes were detectable towards methicillin, aminoglycosides, and phenicols in organic farms. Additionally, AMR genes to macrolides and tetracycline were rare among NAS in organic farms, while such genes were common in conventional husbandries. No differences in AMR detection existed between farm types regarding fosfomycin, lincosamides, fusidic acid, and heavy metal resistance gene presence. The combined data show that husbandry conditions influence the occurrence of resistant and multidrug-resistant bacteria in livestock, suggesting that changing husbandry practices may be an appropriate means of limiting the spread of AMR bacteria on farms.

Epidemiology and antimicrobial resistance of staphylococci other than Staphylococcus aureus from domestic animals and livestock in Africa: a systematic review

Introduction

Staphylococci other than Staphylococcus aureus (SOSA) in animals are becoming more pathogenic and antibiotic resistant and can potentially disseminate to humans. However, there is little synthesized information regarding SOSA from animals in Africa. This systematic review provides a comprehensive overview of the epidemiology and antimicrobial resistance of SOSA in companion animals (pets) and livestock in Africa.

Method

This systematic review (PROSPERO-CRD42021252303) was conducted according to the PRISMA guidelines, and 75 eligible studies from 13 countries were identified until August 2022. Three electronic databases (Pubmed, Scopus and Web of Science) were employed.

Results

The frequently isolated SOSA were S. epidermidis, S. intermedius, S. pseudintermedius, S. xylosus, S. chromogenes, S. hyicus, M. sciuri, S. hominis, and S. haemolyticus. Thirty (40%) studies performed antibiotic susceptibility testing (AST). Penicillin (58%) and tetracycline (28%) resistance were most common across all SOSA with high rates of resistance to aminoglycosides, fluoroquinolones, and macrolides in some species. Resistance to last-resort antibiotics such as linezolid and fusidic acid were also reported. Limited data on strain typing and molecular resistance mechanisms precluded analysis of the clonal diversity of SOSA on the continent.

Conclusion

The findings of this review indicate that research on livestock-associated SOSA in Africa is lacking in some regions such as Central and Western Africa, furthermore, research on companion animals and more advanced methods for identification and strain typing of SOSA need to be encouraged.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021252303.

Review on skeletal disorders caused by Staphylococcus spp. in poultry

Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.

Dynamics and Diversity of Microbial Contamination in Poultry Bedding Materials Containing Parts of Medicinal Plants

Microorganisms thriving in poultry bedding materials during their exploitation are involved in the development of several diseases and disfunctions of animals. They can also contaminate food products and pose risks to the environment and human health. This study provides an analysis of dynamics and diversity in microbiological contamination observed during the exploitation of poultry bedding materials containing parts of medicinal plants: Satureja hortensis, Origanum vulgare, Melissa officinalis, Salvia officinalis, and Thymus vulgaris, compared with standard types of beddings: straw chaff and straw pellets. The research was carried out in two 42-day experimental cycles involving in total 2400 broiler chickens. Each week, the total count of mesophilic bacteria, fungi and yeasts, the presumptive presence and count of Staphylococcus sp., Escherichia sp., Listeria sp., Salmonella sp., and Candida sp. were determined by culturing on selective media, along with pH and moisture measurements. After 35 days of the experiment, a reduction of the total count of mesophilic bacteria above 1 log compared to the control (11.86 vs. 13.02 log CFU/g) was observed. As the count of yeasts decreased after 21 days, an increase in the total count of bacteria was reported, which indicates a strong competition between microorganisms. The results improve our understanding of the temporal effects of using materials containing parts of medicinal plants on the microbial contamination in poultry litter.

Comparison of Naturally Occurring vs. Experimental Infection of Staphylococcus aureus Septicemia in Laying Hens in Two Different Age Groups

In April and November of 2018, multiple commercial laying hen flocks within the same company presented with a sharp increase in mortality and drop in egg production that persisted for several days. These flocks showed striking necropsy lesions consistent with systemic infection and responded to antimicrobial treatment in the feed. Staphylococcus aureus (SA) was the most frequently isolated organism from multiple tissues including comb and wattle lesions, lungs, liver, ovary, spleen, and bone marrow. Given such an uncommon presentation of SA, which is known as a secondary opportunistic pathogen, a challenge study was conducted to evaluate its role in these disease outbreaks. In the present study, laying hens of two ages (22 and 96 wk) were inoculated with SA via three routes: oral gavage, subcutaneous (SC) injection, and intravenous (IV) injection. Both young and old hens in the IV group showed a significant increase in body temperature and drop in body weight; however, the clinical signs observed in the naturally occurring outbreaks were not present. SA was reisolated at multiple time points postchallenge from all challenge groups except the negative control group. While the SC group showed localized necrosis at the injection site, microscopic changes were different from changes observed in birds from the natural outbreaks. Despite observed initial differences in route and age, the SA challenge strain was not capable of reproducing the disease on its own. The results of this study indicate that SA may have played a role in the increased mortality, clinical signs, and necropsy lesions reported with the naturally occurring outbreaks. However, SA should still be considered as a secondary opportunistic pathogen. Other factors that could have caused the initial insult are stress, immunosuppression, or other primary infectious agents. The results of this study may aid veterinary diagnosticians, clinicians, and all poultry professionals to include SA in their differentials list as a secondary opportunistic pathogen in similar cases. This is an uncommon presentation and further field observations and clinical studies are needed to better elucidate the pathogenesis of this disease, which will in turn help to prevent future outbreaks.

Occurrence of Methicillin-Resistant Coagulase-Negative Staphylococci (MRCoNS) and Methicillin-Resistant Staphylococcus aureus (MRSA) from Pigs and Farm Environment in Northwestern Italy

Swine farming as a source of methicillin-resistant Staphylococcus aureus (MRSA) has been well documented. Methicillin-resistant coagulase-negative staphylococci (MRCoNS) have been less studied, but their importance as pathogens is increasing. MRCoNS are indeed considered relevant nosocomial pathogens; identifying putative sources of MRCoNS is thus gaining importance to prevent human health hazards. In the present study, we investigated MRSA and MRCoNS in animals and environment in five pigsties in a high farm-density area of northwestern Italy. Farms were three intensive, one intensive with antibiotic-free finishing, and one organic. We tested nasal swabs from 195 animals and 26 environmental samples from three production phases: post-weaning, finishing and female breeders. Phenotypic tests, including MALDI-TOF MS, were used for the identification of Staphylococcus species; PCR and nucleotide sequencing confirmed resistance and bacterial species. MRCoNS were recovered in 64.5% of nasal swabs, in all farms and animal categories, while MRSA was detected only in one post-weaning sample in one farm. The lowest prevalence of MRCoNS was detected in pigs from the organic farm and in the finishing of the antibiotic-free farm. MRCoNS were mainly Staphylococcus sciuri, but we also recovered S. pasteuri, S. haemolyticus, S. cohnii, S. equorum and S. xylosus. Fifteen environmental samples were positive for MRCoNS, which were mainly S. sciuri; no MRSA was found in the farms’ environment. The analyses of the mecA gene and the PBP2-a protein highlighted the same mecA fragment in strains of S. aureus, S. sciuri and S. haemolyticus. Our results show the emergence of MRCoNS carrying the mecA gene in swine farms. Moreover, they suggest that this gene might be horizontally transferred from MRCoNS to bacterial species more relevant for human health, such as S. aureus.

Biofilm-Formation Ability and the Presence of Adhesion Genes in Coagulase-Negative Staphylococci Isolates from Chicken Broilers

Simple Summary

Bacteria of the genus Staphylococcus are universally present on the mucous membranes and skin of warm-blooded animals. They are divided into two groups on the basis of their ability to clot blood plasma: the coagulase-positive (CoPS) and coagulase-negative staphylococci (CoNS). Some species can cause opportunistic infections in poultry. Identification and characterization of strains of the genus Staphylococcus isolated from farm animals are crucial in epidemiological research and for developing effective methods to treat infections and food poisoning induced by these bacteria. The main virulence factor of coagulase-negative staphylococci is considered to be their ability to form complex biofilm structures on the surfaces of damaged tissues. Biofilms increase the invasive properties of CoNS and their ability to cause infection. The purpose of this study was to determine the biofilm-forming potential of coagulase-negative Staphylococcus strains isolated from poultry. The frequency of selected genes potentially playing a role in the biofilm formation process was also determined. The results of the study indicate that the majority (79.3%) of CoNS isolated from broiler chickens in this study were capable of producing a biofilm.

Abstract

The aim of the study was to analyze the biofilm-production capacity of 87 coagulase-negative Staphylococcus strains (CoNS) isolated from broiler chickens and to determine the occurrence of biofilm-associated genes. The biofilm production capacity of staphylococci was assessed using the microtiter plate method (MTP), and the frequency of genes was determined by PCR. The ability to form a biofilm in vitro was shown in 79.3% of examined strains. Strong biofilm capacity was demonstrated in 26.4% of strains, moderate capacity in 25.3%, weak capacity in 27.6%, and a complete lack of biofilm production capacity in 20.7% of strains. The icaAB gene responsible for the production of extracellular polysaccharide adhesins was detected in 6.9% of strains. The other four genes, i.e., bap (encoding biofilm-associated protein), atlE (encoding cell surface protein exhibiting vitronectin-binding activity), fbe (encoding fibrinogen-binding protein), and eno (encoding laminin-binding protein) were detected in 5.7%, 19.5%, 8%, and 70.1% of strains, respectively. Demonstration of genes that play a role in bacterial biofilm formation may serve as a genetic basis to distinguish between symbiotic and potentially invasive coagulase-negative staphylococcal strains.

The Role of the Coagulase-negative Staphylococci (CoNS) in Infective Endocarditis; A Narrative Review from 2000 to 2020

Coagulase-negative staphylococci (CoNS) are part of the microbiota of human skin and rarely linked with soft tissue infections. In recent years, CoNS species considered as one of the major nosocomial pathogens and can cause several infections such as catheter-acquired sepsis, skin infection, urinary tract infection, endophthalmitis, central nervous system shunt infection, surgical site infections, and foreign body infection. These microorganisms have a significant impact on human life and health and, as typical opportunists, cause peritonitis in individuals undergoing peritoneal dialysis. Moreover, it is revealed that these potential pathogens are mainly related to the use of indwelling or implanted in a foreign body and cause infective endocarditis (both native valve endocarditis and prosthetic valve endocarditis) in patients. In general, approximately eight percent of all cases of native valve endocarditis is associated with CoNS species, and these organisms cause death in 25% of all native valve endocarditis cases. Moreover, it is revealed that methicillin-resistant CoNS species cause 60 % of all prosthetic valve endocarditis cases. In this review, we describe the role of the CoNS species in infective endocarditis, and we explicated the reported cases of CoNS infective endocarditis in the literature from 2000 to 2020 to determine the role of CoNS in the process of infective endocarditis.

Staphylococci in poultry intestines: a comparison between farmed and household chickens

Both pathogenic as well as nonpathogenic species of staphylococci have been reported in poultry, but these studies have not compared staphylococcal flora of both farmed and household broiler chickens. Staphylococci from farmed (n = 51) and household chicken intestines (n = 43) were isolated and tested for resistance to antimicrobials, presence of resistance genes, and inhibitory activity against other bacteria; correlation of resistance phenotype and genotype was also evaluated. At least 12 staphylococcal species were identified; Staphylococcus carnosus subspecies carnosus was the predominant species from both sources. Most farmed chicken staphylococci were resistant to tigecycline (38/51; 74.8%) while the highest level of resistance among the household chicken staphylococci was to clindamycin (31/43; 72.1%). The mecA gene was only detected in staphylococci from household chickens, whereas ermC and tetK or tetM were found in staphylococci from both groups of birds. Multidrug resistance (resistance ≥ 2 antimicrobial classes) was observed in 88% of resistant staphylococci ranging from 2 to 8 classes and up to 10 antimicrobials. Isolates produced inhibitory activity against 7 clinical bacterial strains primarily Enterococcus faecalis (25/88; 28.4%) and Escherichia coli (22/88; 25%). This study demonstrated that the staphylococcal population among farmed and household chickens varies by species and resistance to antimicrobials. These results may reflect the influence of the environment or habitat of each bird type on the intestinal microflora. As resistance in the staphylococci to antimicrobials used to treat human infections was detected, further study is warranted to determine strategies to prevent transfer of these resistant populations to humans via contamination of the poultry meat.

Frequency and Characterization of Antimicrobial Resistance and Virulence Genes of Coagulase-Negative Staphylococci from Wild Birds in Spain. Detection of tst-Carrying S. sciuri Isolates

The objective of this study was to determine the prevalence and diversity of coagulase-negative staphylococci (CoNS) species from wild birds in Spain, as well as to analyze the antimicrobial resistance phenotype/genotype and the virulence gene content. During 2015–2016, tracheal samples of 242 wild birds were collected in different regions of Spain for staphylococci recovery. The species identification was performed using MALDI-TOF. The antimicrobial resistance phenotype and genotype was investigated by the disk diffusion method and by PCR, respectively. The presence of the virulence genes lukF/S-PV, tst, eta, etb, etd and scn was investigated by PCR. Moreover, CoNS carrying the mecA gene were subjected to SCCmec typing. Of the tested animals, 60% were CoNS-carriers, and 173 CoNS isolates were recovered from the 146 positive animals, which belonged to 11 species, with predominance of S. sciuri (n = 118) and S. lentus (n = 25). A total of 34% of CoNS isolates showed a multidrug resistance phenotype, and 42 mecA-positive methicillin-resistant CoNS (MRCoNS) were detected. The isolates showed resistance to the following antimicrobials (percentage of resistant isolates/antimicrobial resistance genes detected): penicillin (49/ blaZ, mecA), cefoxitin (24/ mecA), erythromycin and/or clindamycin (92/ erm(B), erm(C), erm(43), msr(A), mph(C), lnu(A), lsa(B), vga(A) and sal(A)), gentamicin and/or tobramycin (5/ aac(6′)-Ie-aph(2″)-Ia, ant(4′)-Ia), streptomycin (12/str), tetracycline (17/ tet(K), tet(L), tet(M)), ciprofloxacin (4), chloramphenicol (1/ fexA), fusidic acid (86/ fusB, fusD) and trimethoprim–sulfamethoxazole (1/ dfrK). None of the isolates harbored the lukF/S-PV, eta, etb, etd and scn genes, but two S. sciuri isolates (1%) carried the tst gene. Wild birds are frequently colonized by CoNS species, especially S. sciuri. We identified scavenging on intensively produced livestock and feeding on landfills as risk factors for CoNS carriage. High proportions of MRCoNS and multidrug resistant CoNS were detected, which coupled with the presence of important virulence genes is of concern.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry

Simple Summary

This literature review provides a synthesis and evaluation of the current knowledge on Staphylococcus agnetis (S. agnetis) and its implications in poultry pathology. Recent studies revealed that S. agnetis can cause bacterial chondronecrosis with osteomyelitis (BCO), endocarditis, and septicemia in broiler chickens. Lameness constitutes one of the major health and welfare problems causing huge economic losses in the poultry industry. To date, a range of infectious and non-infectious factors have been associated with lameness in poultry. Among bacteria of the genus Staphylococcus, Staphylococcus aureus is the main species associated with locomotor problems. This contrasts with S. agnetis, which until recently had not been considered as a poultry pathogen. Previously only reported in cattle, S. agnetis has expanded its host range to chickens, and due to its unique characteristics has become recognized as a new emerging pathogen. The genotypic and phenotypic similarities between S. agnetis and other two staphylococci (S. hyicus and S. chromogenes) make this pathogen capable of escaping recognition due to misidentification. Although a significant amount of research on S. agnetis has been conducted, many facts about this novel species are still unknown and further studies are required to understand its full significance in poultry pathology.

Abstract

This review aims to summarize recent discoveries and advancements regarding the characteristics of Staphylococcus agnetis (S. agnetis) and its role in poultry pathology. S. agnetis is an emerging pathogen that was primarily associated with mastitis in dairy cattle. After a presumed host jump from cattle to poultry, it was identified as a pathological agent in broiler chickens (Gallus gallus domesticus), causing lameness induced by bacterial chondronecrosis with osteomyelitis (BCO), septicemia, and valvular endocarditis. Economic and welfare losses caused by lameness are global problems in the poultry industry, and S. agnetis has been shown to have a potential to induce high incidences of lameness in broiler chickens. S. agnetis exhibits a distinct repertoire of virulence factors found in many different staphylococci. It is closely related to S. hyicus and S. chromogenes, hence infections caused by S. agnetis may be misdiagnosed or even undiagnosed. As there are very few reports on S. agnetis in poultry, many facts about its pathogenesis, epidemiology, routes of transmission, and the potential impacts on the poultry industry remain unknown.

High concentration of coagulase-negative staphylococci carriage among bioaerosols of henhouses in Central China

Background

Coagulase-negative staphylococci (CoNS) are a group of opportunistic pathogens, which are widely spread in the environment. Animal breeding is an important source of pathogen spreading. However, the concentration and characteristics of CoNS in the bioaerosols of henhouses are unclear.

Results

In this study, we showed that CoNS were significantly increased in bioaerosols of henhouses during the first 60 days, and reached 2.0 × 10⁶ CFU/m³, which account for 75.4% of total bacteria. One hundred and two CoNS isolates from bioaerosols and nasal swabs of farmers were further identified, covering seven species. Among these, 41.2% isolates were Staphylococcus sciuri, which was the predominant species, followed by S. equorum, S. saprophyticus, S. haemolyticus, S. xylosus, S. arlettae and S. gallinarum. There were high rates of resistance to oxacillin in CoNS (49.0%), which were defined as Methicillin-Resistant CoNS (MRCoNS), and 36.3% isolates contained resistance gene mecA. Bioaerosol infection models showed that, chickens exposed to aerosolized S. sciuri had significant induction of inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and IL-10 at 5 days post-infection (dpi) in lungs and at 7 dpi in spleens.

Conclusions

We reported a high concentration of CoNS in henhouses, and S. sciuri was the preponderant CoNS species. Antibiotic resistance analysis and bioaerosols infection of CoNS further highlighted its hazards on resistance and immunological challenge. These results suggested that, CoNS in bioaerosols could be one serious factor in the henhouses for not only poultry industry but also public health.

Antibiotic Susceptibility and Virulence Genes in Enterococcus Isolates from Wild Mammals Living in Tuscany, Italy

Drug resistance is of great importance to human and animal health, but wild environments are still poorly understood in terms of their function as reservoirs of dangerous microbes and resistance determinants. The aim of the study was to determine the antibiotic susceptibility and virulence factors of Enterococcus bacteria from wildlife in Tuscany, Italy. Of the 36 mammalian fecal samples, 52 isolates were derived and classified as Enterococcus faecium (46% of isolates), Enterococcus hirae (19%), Enterococcus faecalis (13%), Enterococcus gallinarum (8%), Enterococcus casseliflavus (6%), Enterococcus durans (4%), Enterococcus mundtii (2%), and Enterococcus canintestini (2%) using both matrix-assisted laser desorption/ionization-time of flight mass spectrometry and methods based on analysis of genetic material. The isolates tested showed the most frequent resistance to tetracycline (36.5% isolates), ciprofloxacin (36.5%), and erythromycin (25%). Three isolates showed high level of resistance (minimal inhibitory concentration ≥1,024 μg/mL) to vancomycin and teicoplanin, and 15% of the isolates demonstrated multidrug resistance. No isolate resistant to ampicillin, linezolid, or streptomycin was found. Among resistance genes, aac(6)-Ii (50% isolates), msrA/B (48%), msrC (42%), and tetM (31%) were identified most frequently. All E. faecium and E. faecalis isolates were positive for the efaAfm and efaAfs genes, respectively. Other virulence-associated genes, that is, gelE, cylA, asa1, esp, ace, orf1481, ptsD, and sgrA, were found in the majority of E. faecalis and several E. faecium isolates. Multilocus sequence typing analysis performed for selected isolates revealed three new sequence types. The results obtained indicate that wild mammals might act as reservoirs of resistance and virulence determinants that could be transferred between different ecosystems.

Evolution of Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Healthy Turkeys in Egypt: First Report of Linezolid Resistance

Coagulase-negative staphylococci (CoNS) are gaining much attention as causative agents of serious nosocomial infections in humans. This study aimed to determine the prevalence and phenotypic antimicrobial resistance of CoNS as well as the presence of resistance-associated genes in CoNS isolated from turkey farms in Egypt. Two hundred and fifty cloacal swabs were collected from apparently healthy turkeys in Egypt. Suspected isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The susceptibility testing of CoNS isolates against 20 antimicrobial agents was performed using the broth microdilution test. The presence of resistance-associated genes like mecA, vanA, blaZ, erm(A), erm(B), erm(C), aac-aphD, optrA, valS, and cfr was determined. Thirty-nine CoNS were identified. All isolates were phenotypically resistant to trimethoprim/sulfamethoxazole, penicillin, ampicillin, and tetracycline. The resistance rates to erythromycin, chloramphenicol, oxacillin, daptomycin, and tigecycline were 97.4%, 94.9%, 92.3%, 89.7%, and 87.2%, respectively. Thirty-one isolates were resistant to linezolid (79.5%). Low resistance rate was detected for both imipenem and vancomycin (12.8%). The erm(C) gene was identified in all erythromycin phenotypically resistant isolates, whereas two resistant isolates possessed three resistance-conferring genes erm(A), erm(B), and erm(C). The cfr and optrA genes were detected in 11 (35.5%) and 12 (38.7%) of the 31 linezolid-resistant isolates. The mecA, aac-aphD, and blaZ genes were identified in 22.2%, 41.9%, and 2.6% of phenotypically resistant isolates to oxacillin, gentamicin, and penicillin, respectively. This is the first study revealing the correlation between linezolid resistance and presence of cfr and optrA genes in CoNS isolates from Egypt, and it can help to improve knowledge about the linezolid resistance mechanism.

Detection of Antibiotic Resistance and Classical Enterotoxin Genes in Coagulase -negative Staphylococci Isolated from Poultry in Poland

Introduction

The study sought to characterise antimicrobial resistance among coagulase-negative Staphylococcus (CNS) species recovered from broiler chickens and turkeys in Poland including the presence of 12 antimicrobial resistance genes and five classical genes of staphylococcal enterotoxins.

Material and Methods

A panel of 11 antimicrobial disks evaluated the phenotypic sensitivity of the tested strains to antibiotics. Five multiplex PCR assays were performed using primer pairs for specific detection of antibiotic resistance genes and staphylococcal enterotoxin A to E genes.

Results

Selected antimicrobial agent susceptibility testing revealed 100% of such in in vitro conditions to cefoxitin among strains of Staphylococcus sciuri and S. chromogenes. The blaZ (for ß-lactam) and mecA (for methicillin resistance) genes were in 58.3% and 27.5% of strains, respectively. Among genes resistant to tetracyclines, tetK was most frequent. Fewer (CNS) strains showed genes resistant to macrolides, lincosamides, and florfenicol/chloramphenicol. Multiplex PCR for classical enterotoxins (A-E) detected the see gene in two S. hominis strains, while the seb gene producing enterotoxin B was found in one strain of S. epidermidis.

Conclusion

CNS strains of Staphylococcus isolated from poultry were either phenotypically or genotypically multidrug resistant. Testing for the presence of the five classical enterotoxin genes showed that CNS strains, as in the case of S. aureus strains, can be a source of food intoxications.

The application of the loop-mediated isothermal amplification (LAMP) method for diagnosing Enterococcus hirae-associated endocarditis outbreaks in chickens

BACKGROUND

Enterococcus hirae is considered a part of the normal intestinal biota of several domestic animals, including poultry. However, this species is also associated with infective endocarditis in chickens, a disease that leads to unexpected deaths and serious economical losses. Enterococcus hirae is identified predominantly with the use of conventional bacteriological methods, biochemical tests and PCR. Rapid, sensitive and specific methods for detecting E. hirae in clinical samples are required in poultry production. The aim of this study was to use the Loop-Mediated Isothermal Amplification (LAMP) for the identification and quantification of E. hirae in heart samples from broiler chickens.

RESULTS

The specificity of the LAMP method was confirmed for 7 enterococcal strains and 3 non-enterococcal strains. E. hirae was detected in all of the 22 analyzed clinical bacterial isolates and in all of the 9 heart samples. Three sets of primers supported the detection of E. hirae with high sensitivity and specificity within one hour. The highest detection rate of a LAMP product was approximately 7 min for an E. hirae strain and 12 min for a positive heart sample. The detection limit for the E. hirae ATCC 10541 standard was 1.3 × 10² CFU (43.4 fg) or 13.8 copies of the E. hirae genome equivalent per reaction. The reaction was 10-fold more sensitive than conventional species-specific PCR. The LAMP assay supported the determination of the E. hirae load in chicken hearts with endocarditis in field cases. The average number of E. hirae cells in hearts was 5.19 × 10⁷ CFU/g of tissue, and the average number of E. hirae genome equivalents in hearts was 5.51× 10⁶ copies/g of tissue. Bacterial counts were significantly higher in the LAMP assay than in the standard plate count.

CONCLUSIONS

The LAMP assay is a useful diagnostic tool and an effective alternative to conventional methods for the detection of this enterococcal species. The sodA-based LAMP assay supported direct identification of E. hirae from pure cultures and heart samples without previous bacterial cultivation. This is the first study to apply the LAMP method for the purpose of diagnosing E. hirae-associated endocarditis in poultry.

Characterization of bacteriophages and their carriage in Staphylococcus aureus isolated from broilers in Poland

1. The objective of this study was the isolation and morphological characterization of temperate bacteriophages induced from Staphylococcus aureus strains isolated from clinical samples from broiler chickens and turkeys. 2. Eighty-five S. aureus strains were tested for susceptibility to oxacillin in order to determine which were methicillin resistant (MRSA). A total of 24 strains showed resistance to methicillin. 3. Thirty-one bacteriophages that were lytic against S. aureus strains were isolated and the host range of the bacteriophages was evaluated. Based on the presence of a specific nucleotide sequence, molecular identification of bacteriophages was performed and the presence of genes responsible for the production of classical enterotoxins (A-E) was also analysed. 4. All the isolated bacteriophages had an icosahedral head and a long, thin, non-contractile flexible tail, characteristic of the family Siphoviridae of the order Caudovirales. Based on multiplex PCR results, the phages were found to belong to serogroups A, B and F (Fa, Fb subgroup), which include mostly temperate phages infecting S. aureus. 5. The titre of the phages ranged from 10^-4 to 10^-9 PFU/ml. The bacteriophages exhibited strong lytic properties against some of the strains of Staphylococcus. The broadest spectrum of activity against the strains was observed in the case of phages sa2, sa3, sa6, sa12, sa15 and sa21. 6. The PCR results showed that of the 31 bacteriophage DNA samples, 4 (12.9%) appeared to have enterotoxigenic genes.