Methicillin-resistant Staphylococcus epidermidis blepharitis

Antimicrobial resistance of ocular microbes and the role of antimicrobial peptides

Isolation of antimicrobial-resistant microbes from ocular infections may be becoming more frequent. Infections caused by these microbes can be difficult to treat and lead to poor outcomes. However, new therapies are being developed which may help improve clinical outcomes. This review examines recent reports on the isolation of antibiotic-resistant microbes from ocular infections. In addition, an overview of the development of some new antibiotic therapies is given. The recent literature regarding antibiotic use and resistance, isolation of antibiotic-resistant microbes from ocular infections and the development of potential new antibiotics that can be used to treat these infections was reviewed. Ocular microbial infections are a global public health issue as they can result in vision loss which compromises quality of life. Approximately 70 per cent of ocular infections are caused by bacteria including Chlamydia trachomatis, Staphylococcus aureus, and Pseudomonas aeruginosa and fungi such as Candida albicans, Aspergillus spp. and Fusarium spp. Resistance to first-line antibiotics such as fluoroquinolones and azoles has increased, with resistance of S. aureus isolates from the USA to fluoroquinolones reaching 32 per cent of isolates and 35 per cent being methicillin-resistant (MRSA). Lower levels of MRSA (seven per cent) were isolated by an Australian study. Antimicrobial peptides, which are broad-spectrum alternatives to antibiotics, have been tested as possible new drugs. Several have shown promise in animal models of keratitis, especially treating P. aeruginosa, S. aureus or C. albicans infections. Reports of increasing resistance of ocular isolates to mainstay antibiotics are a concern, and there is evidence that for ocular surface disease this resistance translates into worse clinical outcomes. New antibiotics are being developed, but not by large pharmaceutical companies and mostly in university research laboratories and smaller biotech companies. Antimicrobial peptides show promise in treating keratitis.

Slime Production by Coagulase-Negative Staphylococci Isolated in Chronic Blepharitis

Background

The purpose of the study was to determine the impact of slime-producing strains of coagulase-negative staphylococci (CNS) on non-ulcerative blepharitis. Formerly considered harmless organisms, CNS are now recognised as opportunistic pathogens. Although these microorganisms are a component of normal conjunctival flora, they often produce the typical signs and symptoms of chronic staphylococcal blepharoconjunctivitis. Certain strains produce a polysaccharide extracellular material called “slime”. Slime production is considered to be associated with the virulence of the organism.

Methods

Swabs were taken from the lids of 38 eyes of 19 patients with chronic non-ulcerative blepharitis and cultured for CNS. A group of 42 normal control eyes were similarly sampled. The strains of CNS isolated from 26 eyes (68.4%) of the patients with blepharitis and 25 eyes (59.5%) of the normal subjects were studied for slime layer production.

Results

No significant difference was found between normal subjects and patients in the incidence of slime producing CNS strains from the conjunctiva. The antibiotic sensitivity profiles of the slime-producing strains were no different from the slime-negative isolates in the blepharitis (p=0.85) and normal group (p=0.25).

Conclusions

Our data suggest that slime production by CNS does not play a significant role in the pathogenesis of staphylococcal blepharitis.

Current knowledge about and recommendations for ocular methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is the most important and common pathogen that infects patients following cataract surgery, laser in situ keratomileusis, and photorefractive keratectomy. It is reported to be the second most common pathogen causing bacterial keratitis around the world. Of special concern are increasing reports of postoperative methicillin-resistant S aureus (MRSA) infection. For example, MRSA wound infections have been reported with clear corneal phacoemulsification wounds, penetrating keratoplasty, lamellar keratoplasty, and following ex vivo epithelial transplantation associated with amniotic membrane grafts. These and other data suggest that MRSA has become increasingly prevalent worldwide. In this article, we review the current medical literature and describe the current challenge of ocular MRSA infections. Recommendations are made based on an evidence-based review to identify, treat, and possibly reduce the overall problem of this organism.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Susceptibility of methicillin-resistant Staphylococci clinical isolates to netilmicin and other antibiotics commonly used in ophthalmic therapy

PURPOSE

The aim of this study was to test the activity of selected antimicrobial agents commonly used in the treatment of ocular infections against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) isolates.

METHODS

A total of 43 staphylococci from respiratory tract and ocular infections were characterized for methicillin resistance using the Epsilometer test (E-test), the polymerase chain reaction for mecA gene detection and the PBP2' latex agglutination test. A perfect agreement among them was observed in 20 isolates (8 MRSA and 12 MRSE) which were then employed in the susceptibility test by using the agar disk diffusion test (NCCLS). The antibiotics tested were: netilmicin (NET), tobramycin (TOB), azithromycin (AZM), levofloxacin (LEV), moxifloxacin (MXF), chloramphenicol (C) and vancomycin (VA).

RESULTS

All MRSE and most (87.5%) of MRSA isolates tested were NET and VA sensitive. The majority of MRSA were found to be resistant to all the other antibiotics, with the exception of C. In particular, 75%, 87% and 100% of the isolates were resistant to fluoroquinolones (LEV and MXF), AZM and TOB, respectively. As for the MRSE group, 25% of the strains tested were resistant to C and MXF while 33%, 42% and 58% of the strains were resistant to LEV, AZM and TOB, respectively.

CONCLUSIONS

Together with VA, NET was the most effective antibiotic tested against both MRSA and MRSE clinical isolates. The exclusive topical use of NET for the treatment of ocular infections may curtail the emergence, spreading and persistence of antibiotic-resistant bacteria.

Two cases of corneal ulcer due to methicillin-resistant Staphylococcus aureus in high risk groups

Considering the popular use of antibiotic-containing eyedrops in Korea, it is important to know the emerging antibiotic-resistant strains of bacteria before treating infectious eye diseases. This is especially important in high-risk groups because of the high incidence of resistant infections and the subsequent treatment requirements. We report two cases of methicillin-resistant Staphylococcus aureus (MRSA) corneal ulcers in high-risk groups. The first case involved a patient who had keratitis after using antibiotic- and steroid-containing eyedrops to treat a corneal opacity that developed after repeated penetrating keratoplasty. The second case involved a patient who used antibiotic-containing eyedrops and a topical lubricant on a regular basis for >1 month to treat exposure keratitis due to lagophthalmos. The second patient's problems, which included a persistent superficial infiltration, developed after brain tumor surgery. Both cases showed MRSA on corneal culture, and the corneal ulcers improved in both patients after the application of vancomycin-containing eyedrops. In conclusion, MRSA infection should be considered in corneal ulcers that have a round shape, mild superficial infiltration, and slow progression, especially in high-risk groups. This report includes descriptions of the characteristic features, antibiotic sensitivities, prevention, and successful treatment with vancomycin-containing eyedrops for MRSA corneal ulcers.

Methicillin-resistant Staphylococcus aureus infections after scleral buckling procedures for retinal detachments associated with atopic dermatitis

OBJECTIVE

To determine the incidence and the clinical course of methicillin-resistant Staphylococcus aureus as a cause of acute-onset infections in patients with atopic dermatitis after a scleral buckling procedures.

DESIGN

A retrospective chart review.

PARTICIPANTS

Two hundred eighty-seven patients (293 eyes) who underwent scleral buckling procedures to treat rhegmatogenous retinal detachments at either Osaka Rosai Hospital or Osaka University Medical School between July 1, 1995, and June 30, 1997, participated. Of these, 32 eyes (10.9%) were associated with atopic dermatitis.

INTERVENTION

Demographic and clinical data were abstracted from patients' medical records.

MAIN OUTCOME MEASURES

The incidence, clinical features, and management of postoperative infections associated with methicillin-resistant S. aureus were studied.

RESULTS

Methicillin-resistant S. aureus infection after scleral buckling procedures was identified in 6 (18.8%) of 32 eyes of patients with atopic dermatitis but in only 1 (0.4%) of the other 261 cases without atopic dermatitis (P < 0.001). The average interval from the scleral buckling procedures to the initial onset of infection was 8.3 +/- 9.1 days (range, 2-28 days). Bacterial infection and inflammation were controlled in four eyes by prompt removal of the infected buckle in combination with vancomycin administration. In the other three eyes, however, repeat intravitreous injections of vancomycin or emergent vitrectomies were required because of the development of endophthalmitis.

CONCLUSIONS

Methicillin-resistant S. aureus is an important causative pathogen of scleral buckling infections, particularly in patients with retinal detachment associated with atopic dermatitis. Preoperative evaluation and intraoperative attention to contamination are recommended to prevent methicillin-resistant S. aureus infections in these patients.

Successful treatment of methicillin-resistant Staphylococcus aureus Keratitis with topical ciprofloxacin

Ciprofloxacin is a new quinolone antibiotic with a broad spectrum of activity against most aerobic gram-positive and gram-negative bacteria. Topical ciprofloxacin (3 mg/ml) was used to treat bacterial keratitis caused by methicillin-resistant strains of Staphylococcus aureus in two patients. Both corneal ulcers had been previously treated with other antibiotics without success. Topical ciprofloxacin was curative in both cases. The authors recommend the use of topical ciprofloxacin for methicillin-resistant S. aureus keratitis.

Blepharitis--a diagnostic and therapeutic challenge. A report on 407 consecutive cases

Over the last few years the number of patients with chronic bilateral blepharitis has increased dramatically. From January 1985 until the end of 1989, a total of 407 patients with this diagnosis underwent ophthalmological and dermatological investigations at our out-patient clinic. Keratoconjunctivitis sicca (KCS) in conjunction with blepharitis occurred in 14.5% of the patient population who also suffered from acne rosacea. A comparison of the spectrum of microorganisms that have previously been isolated from affected sites with data obtained in the present study revealed that the range of microorganisms associated with this chronic localized inflammation has apparently shifted in recent years. The prevalence of Staphylococcus aureus, which was considerable in the pre-antibiotic era, has markedly decreased, although a distinct entity of staphylococcal blepharitis seems to remain, either alone or in combination with seborrheic blepharitis (62.8% of our patients). The clinical picture, microbiological findings and therapy for this condition are presented.

Topical vancomycin for the treatment of Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus conjunctivitis

Staphylococcus aureus and Staphylococcus epidermidis are organisms that frequently cause conjunctivitis or blepharoconjunctivitis. We describe a patient with methicillin-resistant S. aureus and S. epidermidis conjunctivitis who was treated successfully using an extemporaneously prepared topical ophthalmic solution of vancomycin hydrochloride 31 mg/mL. Studies describing the preparation, stability, and comfort of this solution, as well as reports pertaining to efficacy, are reviewed. Controlled clinical trials evaluating the safety and efficacy of vancomycin ophthalmic solution have not yet been performed.

Efficacy and safety of mercuric oxide in the treatment of bacterial blepharitis

A double-masked, placebo-controlled, randomized study was done to assess the safety and clinical and quantitative microbiologic efficacy of 1% mercuric oxide (yellow) ophthalmic ointment in the treatment of eyelid infections, i.e., bacterial blepharitis. A total of 39 patients with bacterial counts and clinical signs indicative of eyelid infection were treated twice daily for 7 days. Clinical biomicroscopic examination and quantitative microbiologic cultures were done just prior to initiation of treatment and again on days 3 and 7. Statistical analysis revealed a significant improvement in the clinical signs, bacterial count, cure rate, and improvement rate for subjects taking the active medication, compared with those taking the placebo on days 3 and 7. In addition, the medication was well tolerated.

Effects of fusidic acid on staphylococcal keratitis

We treated 20 consecutive patients suffering from staphylococcal keratitis with topical fusidic acid 1% suspension in a carbomer gel. Fifteen (79%) of the isolated Staphylococcus epidermidis strains were resistant to methicillin, but all were sensitive to fusidic acid by in-vitro testing. The keratitis showed evidence of healing in 17 (85%) of the 20 patients. The healing times ranged between 5 and 21 days (mean 10.5 days). In this open clinical trial fusidic acid proved to be a safe and effective antibiotic for the treatment of staphylococcal keratitis.

Topical vancomycin formulation for methicillin-resistant Staphylococcus epidermidis blepharoconjunctivitis

We successfully treated two patients with severe Staphylococcus epidermidis blepharoconjunctivitis by means of a topical vancomycin hydrochloride solution (50 mg/ml) prepared with sterile water. Aqueous vancomycin preparations, however, cause significant ocular irritation probably because of low pH and osmolality values. Solutions prepared with normal saline (5 mg/ml) and phosphate-buffered artificial tears (5 mg/ml and 50 mg/ml) were significantly less irritating and possessed equivalent in vitro antimicrobial activity. Topical vancomycin should be used only when commercially available antibiotics are inadequate.

A retrospective review of endophthalmitis due to coagulase-negative staphylococci

We retrospectively reviewed 28 cases of postoperative endophthalmitis due to coagulase-negative staphylococci. There was an average delay between surgery and the acute presentation of 7 X 2 days (SD 3 X 3). All patients were treated with intraocular antibiotics (IOAB) or therapeutic vitrectomy with IOAB. In six of the 28 cases the organisms were resistant to gentamicin as measured by the Kirby-Bauer technique; none was resistant to cephalosporins. Isolates that had been stored by lyophilisation were reconstituted and tested by serial dilution; none was resistant to gentamicin, though two were borderline. The final visual acuity was 6/18 or better in 72% of the eyes.