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Visual image of the corneal ulcer on day 5. Fluorescein staining revealed a corneal ulcer of 20 mm in diameter. Negative staining at the center of the ulcer indicated descemetocele.
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We report the first case of methicillin-resistant Staphylococcus aureus (MRSA) keratitis in a racehorse. A 5-year-old mare developed punctate keratitis after racing. The corneal ulcer continued to expand despite ophthalmic antimicrobial therapy. On day 6, a conjunctival graft surgery was performed. The mare was euthanized, following colitis and lam...
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To evaluate abnormalities of the cornea, lens and body and eye weight variation due to mitomycin C instillation in eyes of 79 weanling Wistar female rats we realized two studies. Two drops of mitomycin C in distilled water at 0.02%, 0.04%, 0.08% and 0.16% were instilled 4 times daily for 14 days. The animals were weighed daily during this period an...
Citations
... The antimicrobial disks were selected based on the active principles most frequently used in the ophthalmic treatment routine of horses. Topical gentamicin and chloramphenicol are antibiotics indicated for the preventive treatment of corneal ulcers in horses [23,24]; chloramphenicol is still effective against MRSA strains [25]. ...
This work aimed to characterize S. aureus isolates from the eyes of healthy and clinically affected equines in the Kafrelsheikh Governorate, Egypt. A total of 110 animals were examined for the presence of S. aureus, which was isolated from 33 animals with ophthalmic lesions and 77 healthy animals. We also investigated the antimicrobial resistance profile, oxacillin resistance mechanism, and the major virulence factors implicated in many studies of the ocular pathology of pathogenic S. aureus. The association between S. aureus eye infections and potential risk factors was also investigated. The frequency of S. aureus isolates from clinically affected equine eyes was significantly higher than in clinically healthy equids. A significant association was found between the frequency of S. aureus isolation from clinically affected equine eyes and risk factors including age and season but not with sex or breed factors. Antimicrobial resistance to common antibiotics used to treat equine eyes was also tested. Overall, the isolates showed the highest sensitivity to sulfamethoxazole (100%) and the highest resistance to cephalosporin (90.67%) and oxacillin (90.48%). PCR was used to demonstrate that mecA was present in 100% of oxacillin- and β-lactam-resistant S. aureus strains. The virulence factor genes Spa (x region), nuc, and hlg were identified in 62.5%, 100%, and 56%, of isolates, respectively, from clinically affected equines eyes. The severity of the eye lesions increased in the presence of γ-toxin-positive S. aureus. The phylogenetic tree of the Spa (x region) gene indicated a relationship with human reference strains isolated from Egypt as well as isolates from equines in Iran and Japan. This study provides insight into the prevalence, potential risk factors, clinical pictures, zoonotic potential, antimicrobial resistance, and β-lactam resistance mechanism of S. aureus strains that cause eye infection in equines from Egypt.
... The antimicrobial disks were selected based on the active principles most frequently used in the ophthalmic treatment routine of horses. Topical gentamicin and chloramphenicol are antibiotics indicated for the preventive treatment of corneal ulcers in horses [23,24]; chloramphenicol is still effective against MRSA strains [25]. ...
Citation: Tahoun, A.; Elnafarawy, H.K.; El-Sharkawy, H.; Rizk, A.M.; Alorabi, M.; El-Shehawi, A.M.; Youssef, M.A.; Ibrahim, H.M.M.; El-Khodery, S. The Prevalence and Molecular Biology of Staphylococcus aureus Isolated from Healthy and
... All of the isolates were methicillin-sensitive using the cefoxitin disc susceptibility test [21]. According to literature, methicillin-resistant Staphylococcus aureus (MRSA) was isolated in one case of ulcerative keratitis in a horse in Japan [23]. Methicillin-resistant Staphylococci (MRS) were also isolated from a horse with a surgical wound complication as well as from the nares and skin of healthy horses [24][25][26]. ...
Background:
Commensal bacterial and fungal flora of the conjunctival sac has been described in horses and other animals. The identification of commensal flora of the conjunctival sac may aid in the diagnosis of ocular inflammatory diseases, such as conjunctivitis or more severe ulcerative keratitis, common in horses. Moreover, damage of ocular protective barriers may lead to an opportunistic infection. The study was carried out in Silesian horses kept at a single breeding center in South-western Poland, in order to limit any breed-dependant and climate-dependant variables affecting the results. Following an ophthalmic examination that revealed no abnormalities, sterile swabs were collected from conjunctival sac in 26 adult horses and 11 foals. The obtained swabs were subjected to bacterial culture testing. In case of Staphylococcus spp. isolation, susceptibility to methicillin was evaluated.
Results:
Forty- three bacterial isolates, representing eleven genera of bacteria were cultured from 30 (81%) horses. Gram-positive bacteria were the dominant isolates (72%) (p < 0.001). The most commonly isolated Gram-positive bacteria were Staphylococcus spp., while Moraxella spp. were the most frequently isolated Gram-negative bacteria. There was no significant influence of sex and age on the frequency and type of microbial isolates.
Conclusions:
Commensal flora is present in the conjunctival sac of healthy horses in Poland. Age does not affect the abundance and type of microbial isolates.
... Moreover, the semi-quantitative assessment revealed a rather low growth rate (cfu/plate) for five of the six ocular swabs(Table 1), indicating most likely a temporal contamination rather than an infection. However, MRSA contamination of eyes prior to invasive procedures might be a risk factor for post-invasive complications(Hayashi et al., 2017), since severe ocular disease associated with MRSA was reported in horses before(Anderson et al., 2009;Kuroda et al., 2015).All MRSA isolates showed the same resistance pattern including resistance to β-lactams[mecA, blaZ], tetracyclines [tet(M)], aminoglycosides [aacA-aphC], and trimethoprim/sulfamethoxazole[dfrK]. The detected resistance genes are commonly found among S. aureus from animals(Schwarz et al., 2014; Wendlandt et al., 2013).Moreover, the isolates proved to be resistant to fluoroquinolones and revealed several amino acid substitutions in the subunits of the gyrase (Ser84Leu in GyrA, Glu182Asp in GyrB) and the topoisomerase IV (Ser80Phe, Val590Ile and Val656Ile in GrlA and Ile72Thr, Glu422Asp and Glu596Asp in GrlB) were detected. ...
Severe infections due to methicillin-resistant Staphylococcus aureus (MRSA) have been increasingly recognized in virtually all fields of veterinary medicine. Our objective was to study the occurrence, phylogenetic relationships and antimicrobial resistance properties of MRSA isolated from ocular surfaces of horses prior to invasive procedures. Within a 49-week sampling period, ocular swabs obtained from 46 eyes of 44 horses, including eyes with clinical signs of conjunctivitis/blepharitis, keratitis or uveitis were screened for the presence of S. aureus. As a result, seven samples were positive for S. aureus (15.2%), with six of them being classified as MRSA (13%). In addition, all isolates were resistant or showed reduced susceptibility to tetracyclines, the aminoglycosides gentamicin and kanamycin, fluoroquinolones, and the combination sulfamethoxazole/trimethoprim. Since a very close relationship between the MRSA isolates was assumed after pulsed-field gel electrophoresis employing the restriction endonuclease ApaI, whole genome sequencing (WGS) was used to shed more light on the phylogenetic relationships and the molecular composition of all MRSA isolates. Analysis of WGS data revealed closely related MRSA belonging to sequence type 398, spa type t011 and dru type dt10q, harboring an SCCmec IV element and the Staphylococcus aureus pathogenicity island SaPIbov5. Moreover, all MRSA were positive for a beta-hemolysin converting phage carrying genes of the immune evasion cluster (IEC). Since cases of eye infections due to MRSA were often associated with fatal outcomes, more research is needed with respect to the origin of MRSA isolated from ocular surfaces to implement sufficient barrier and infection control measures.
... Injury to the cornea, invaded by resident, pathogenic or potentially pathogenic microorganisms, leads to keratitis or infected corneal ulcers, which can be difficult to treat and can result in vision loss (MOORE et al. 1988;KURODA et al., 2015). Ferreira et al. ...
... Plates were incubated for 24h in an incubator, and growth inhibition around each disk was then analyzed, classifying the bacteria as sensitive, intermediate or resistant to the antibiotic. The criteria for the choice of antimicrobials testes were based on the active principles most frequently used in the ophthalmic routine of horses in the Federal District, in addition, topical gentamicin and chloramphenicol are the antibiotics indicated for the preventive treatment of corneal ulcers in horses (SAUER et al., 2003;WADA et al., 2010;JOHNS et al., 2011), with chloramphenicol being still effective against strains of MRS, an emerging infection among equines (KURODA et al., 2015). ...
... In horses, several sites of MRSA infection have been reported, including skin, respiratory, urinary and reproductive tract ( VAN SPIJK et al., 2016). MRSA-infected keratitis has been described in humans (ONGs et al., 2013) and dog (TAGIMA et al., 2013), and recently in a race mare resulting in a fatal condition (KURODA et al., 2015). ...
The aim of this study was to identify the conjunctival bacterial flora of healthy horses in Brasilia (Distrito Federal, Brazil), and to evaluate the antimicrobial susceptibility of the isolated strains. We examined 200 eyes of 100 healthy adult horses without any eye problems, belonging to the 1st Regiment of the Cavalry Guard (RCG) of the Brazilian Army in Brasilia. Samples were collected from the inferior conjunctival fornix of both eyes. Drug sensitivity test was performed with the antibiotics gentamicin (10µg), tobramycin (10µg), chloramphenicol (30µg) and ciprofloxacin (5µg). Of the 200 samples collected, 131 (65.5%) were considered positive for bacterial growth. A total of 208 bacterial strains belonging to 19 genera were isolated, where there was prevalence of gram-positive bacteria (65%), with Staphylococcus sp. being the species of greatest incidence. It was observed that 94, 85, 81 and 68% of the isolates were sensitive to ciprofloxacin, gentamicin, chloramphenicol and tobramycin, respectively. These results can guide the empirical selection antimicrobial therapy for infections of the ocular surface of horses, pending the identification of the etiologic agent.
This study aims to determine the microbiological profile and risk factors associated with antimicrobial-resistant bacteria in canine severe corneal ulcers. Thirty-two corneal and conjunctival swabs were collected from dogs with diagnosed severe corneal ulcers that presented to Prasu-Arthorn veterinary teaching hospital in Nakhon Pathom, Thailand from June 2015 to June 2016. Microorganisms were identified by means of genotypic and phenotypic approaches. Of 32 ulcers sampled, 26 (81.3%) yielded culturable microorganisms with 24 bacterial isolates and 7 fungal isolates. The most commonly isolated bacteria were Staphylococcus spp. (45.8%, 11/24) and Pseudomonas aeruginosa (20.8%, 5/24). Out of 11 staphylococcal isolates identified, 10 carried the mecA gene providing methicillin resistance. The extended-spectrum β-lactamase (ESBL) encoding genes blaCTX-M and blaVEB-1were found in an Acinetobacter lwoffii isolate, and blaSHV was found in a P. aeruginosa isolate. Based on the Clinical Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoint criteria, minimum inhibitory concentrations values showed that all bacteria, except for staphylococci, were susceptible to current ophthalmic antibiotics. More than 50% of staphylococci were resistant to all generations of fluoroquinolones and fusidic acid. Chloramphenicol was highly active against staphylococci (81.3% susceptible). The width (P=0.02) and the depth (P=0.04) of ulcers predicted greater risk of yielding resistant bacteria. The identification of antimicrobial-resistant bacteria prompts practitioners to be prudent when choosing ophthalmic antibiotics for severe corneal ulcers.
When dealing with horses suffering from gastrointestinal disease, one must remain constantly vigilant both for the potential role of infectious etiologies and for the risk of infectious complications in these patients. The development and diligent implementation of infection control practices and surveillance are required in order to minimize the risk of nosocomial infections, and to minimize their severity and dissemination when they do occur. Although the responsibility for effective implementation rests with all staff members, the designation of specific individuals with responsibility for oversight and maintenance of standards can be extremely helpful in ensuring the effectiveness of the biosecurity program. Ongoing training of all caregivers regarding both the underlying concepts and the practices involved in biosecurity is essential in this process.
Objective:
To explore the impact of equine corneal fibroblast (ECF) to myofibroblast (ECM) differentiation by altering the expression of the Smad genes either individually or in combination. Specifically, we sought to examine the ECF differentiation after (a) silencing of Smad2, 3, and 4 profibrotic genes individually and (b) overexpression of antifibrotic Smad7 gene and in a combination with pro- and antifibrotic Smad genes.
Methods:
Equine corneal fibroblast primary cultures were generated as previously described. ECFs were transfected with individual plasmids which silenced gene expression of either Smad2, 3, or 4 or in combination with a plasmid overexpressing Smad7 using Lipofectamine 2000™ or Lipofectamine BLOCK-iT™. Smad-transfected clones were then exposed to TGF-β1 to induce differentiation to myofibroblasts. Immunofluorescence and qRT-PCR techniques quantified levels of ECF differentiation to ECM by measuring alpha smooth muscle actin, a known marker of ECM transdifferentiation.
Results:
Silencing of individual Smad2, 3, or 4 genes or overexpression of Smad7 showed significant inhibition of ECF transdifferentiation (73-83% reduction). Silencing of Smad2 showed the greatest inhibition of ECF transdifferentiation in (a) and was therefore utilized for the combination gene transfer testing. The combination gene transfer consisting of Smad7 overexpression and Smad2 silencing attenuated ECF differentiation significantly; however, the level was not significant compared to the overexpression of Smad7 individually.
Conclusions:
Using gene transfer technology involving profibrotic Smad silencing, antifibrotic Smad overexpression or its combination is a novel strategy to control TGF-β1-mediated fibrosis in equine fibroblasts. Combination gene therapy was not better than single gene therapy in this study.
METICILLIN-resistant Staphylococcus aureus (MRSA) is a major health problem in people. About 30 per cent of the general population are nasal carriers of Staphylococcus aureus , and only a small proportion carry MRSA (Kluytmans and others 1997, Mainous and others 2006). However, in a hospital environment this proportion is generally much higher, although large differences exist between countries. Healthcare workers are regularly colonised (transiently or persistently) and are likely to play a role in the transmission within the hospital setting (Albrich and Harbarth 2008).
In horses, MRSA seems to behave in a similar way. Healthy horses carry MRSA at low prevalence, but in equine hospitals the prevalence is much higher (Van Balen and others 2014, Tirosh-Levy and others 2015) and nosocomial MRSA infections in horses leading to serious and sometimes fatal conditions have previously been described (Kuroda and others 2015). However, the high prevalence of MRSA in equine hospitals is not only a risk for the horses, but also for the personnel involved. Veterinarians are at an increased risk of carrying MRSA compared to the general population, but equine veterinarians are at an even higher risk than veterinarians working with other animal species (Jordan and others 2011, Cuny and others 2016). Transmission from hospitalised horses to their veterinarians therefore seems to occur, but as in the human healthcare situation where healthcare workers may infect patients, …
