Ophthalmic Manifestations of Infections Caused by the USA300 Clone of Community-Associated Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus Keratitis in Taiwan: Genotyping, Antibiotic Susceptibility, and Clinical Features

Staphylococcus aureus is an important pathogen for keratitis, a vision-threatening disease. We aimed to investigate the genotyping, antibiotic susceptibility, and clinical features of S. aureus keratitis, and to explore the possible role of Panton–Valentine leucocidin (PVL), a major virulence factor of S. aureus. We recruited 49 patients with culture-proven S. aureus keratitis between 2013 and 2017 at Chang Gung Memorial Hospital, Taiwan. PVL gene, multilocus sequence type (MLST), staphylococcal cassette chromosome mec (SCCmec), and pulsed-field gel electrophoresis (PFGE) were performed. Antibiotic susceptibility was verified using disk diffusion/E test. There were 49 patients with S. aureus keratitis; 17 (34.7%) were caused by methicillin-resistant S. aureus (MRSA) and 9 (18.4%) isolates had PVL genes. The predominant genotyping of MRSA isolates was CC59/PFGE type D/SCCmec VT/PVL (+). All methicillin-sensitive S. aureus (MSSA) and approximately 60% MRSA were susceptible to fluoroquinolones. No significant differences in clinical features, treatments, and visual outcomes were observed between MRSA/MSSA or PVL(+)/PVL(−) groups. In Taiwan, approximately one third of S. aureus keratitis was caused by MRSA, mainly community-associated MRSA. Although MRSA isolates were more resistant than MSSA, clinical characteristics were similar between two groups. Fluoroquinolones could be good empiric antibiotics for S. aureus keratitis.

Endogenous Methicillin-Resistant Staphylococcus Aureus (MRSA) Endophthalmitis: A Six-year Series at a Tertiary Care Center

PURPOSE

To investigate the clinical outcomes of methicillin-resistant Staphylococcus aureus (MRSA) endophthalmitis.

METHODS

Clinical courses were reviewed for 17 eyes (15 patients) with endogenous MRSA endophthalmitis based on positive blood and vitreous culture or clinical suspicion between 2013 to 2019 at Duke University Hospitals.

RESULTS

Of 17 eyes, initial VA ranged from 20/40 to light perception. Of 15 patients, 9 had predisposing risk factors for bacteremia. All eyes received intravitreal vancomycin, 13 also received ceftazidime, and 2 also received amikacin instead of ceftazidime. Nine eyes developed retinal detachment; 6 underwent vitrectomy. Final VA ranged from 20/20 to no light perception and was ≥20/200 in 8 eyes. Eleven eyes had improved VA, 2 eyes were unchanged, and 4 were worse.

CONCLUSIONS

This study is the largest series on endogenous MRSA endophthalmitis to date. Patients had a higher proportion of final VA ≥20/200, similarly high rate of RD, and fewer enucleations compared to prior reports.

Risk factors for enucleation or evisceration in endophthalmitis

PURPOSE

To identify clinical risk factors for enucleation or evisceration in patients with endophthalmitis at an academic institution.

METHODS

A retrospective review of patients diagnosed with endophthalmitis at Wilmer Eye Institute from 2010 to 2019 was conducted. Clinical characteristics, including demographics, cause for endophthalmitis, microbial culture results, salvaging procedures and surgical intervention were recorded. In patients who underwent enucleation or evisceration, type of surgery and placement of a primary implant were recorded. Chi-squared, Student's t-tests and multivariate analysis were used to identify clinical factors that predicted enucleation or evisceration.

RESULTS

Two hundred and fifty three patients treated for endophthalmitis over the study period were identified, of which 25 (9.88%) underwent enucleation or evisceration. Risk factors for enucleation or evisceration included poor presenting visual acuity (OR 7.86, CI: 2.26, 27.3), high presenting intraocular pressure (OR 1.07, CI: 1.03, 1.12), presence of relative afferent pupillary defect (OR 3.69, CI: 1.20, 11.37) and positive vitreous culture for methicillin-resistant staphylococcus aureus (MRSA) (OR 18.3, CI: 1.54, 219.2) on multivariate analysis. Patients undergoing enucleation or evisceration were also more likely to have trauma, corneal ulcer or combined causes for endophthalmitis and underwent fewer salvaging surgical and procedural interventions. There were no significant differences in characteristics of those receiving enucleation versus evisceration in our cohort.

CONCLUSION

Patients with endophthalmitis who underwent enucleation or evisceration had more severe disease on presentation compared to those treated with eye sparing therapy. Presenting clinical characteristics may have a role in triage and management decisions for patients presenting with severe endophthalmitis.

Hospital-Associated Multidrug-Resistant MRSA Lineages Are Trophic to the Ocular Surface and Cause Severe Microbial Keratitis

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of severe and difficult to treat ocular infection. In this study, the population structure of 68 ocular MRSA isolates collected at Massachusetts Eye and Ear between January 2014 and June 2016 was assessed. By using a combination of multilocus sequence typing (MLST) analysis, SCCmec typing and detection of the panton-valentine leukocidin (PVL) gene, we found that the population structure of ocular MRSA is composed of lineages with community and hospital origins. As determined by eBURST analysis of MLST data, the ocular MRSA population consisted of 14 different sequence types (STs) that grouped within two predominant clonal complexes: CC8 (47.0%) and CC5 (41.2%). Most CC8 strains were ST8, harbored type IV SCCmec and were positive for the PVL-toxin (93.7%). The CC5 group was divided between strains carrying SCCmec type II (71.4%) and SCCmec type IV (28.6%). Remaining isolates grouped in 6 different clonal complexes with 3 isolates in CC6 and the other clonal complexes being represented by a single isolate. Interestingly, major MRSA CC5 and CC8 lineages were isolated from discrete ocular niches. Orbital and preseptal abscess/cellulitis were predominantly caused by CC8-SCCmec IV PVL-positive strains. In contrast, infections of the cornea, conjunctiva and lacrimal system were associated with the MDR CC5 lineage, particularly as causes of severe infectious keratitis. This niche specialization of MRSA is consistent with a model where CC8-SCCmec IV PVL-positive strains are better adapted to cause infections of the keratinized and soft adnexal eye tissues, whereas MDR CC5 appear to have greater ability in overcoming innate defense mechanisms of the wet epithelium of the ocular surface.

Endophthalmitis in HIV Infection

Purpose: The role of HIV infection in exogenous and endogenous endophthalmitis has not been clarified. We aim to assess the potential role of HIV as a risk factor or a poor prognostic feature in this sight-threatening condition. Methods: Literature review. Review of evidence: Evidence for endophthalmitis in HIV patients is based on scarce retrospective case series and case reports. Infrequency of literature on this topic is owed to the diversity of the different types of endophthalmitis as well as the rarity of the coexistence of the two conditions. Conclusions: Endophthalmitis in HIV patients are a rare but potentially devastating condition. Many forms of endophthalmitis tend to occur in severely immunosuppressed HIV patients with low CD4 counts. Therefore, the early introduction of cART with full immune reconstitution is an essential part of the prevention of endophthalmitis in the HIV population.

Periorbital infections and conjunctivitis due to Panton-Valentine Leukocidin (PVL) positive Staphylococcus aureus in children

Background

Colonisation with Panton-Valentine Leukocidin expressing strains of Staphylococcus aureus (PVL + SA) is characterised by recurrent skin and soft tissue infections. While periorbital and orbital infections are common in children and frequently caused by S. aureus the role of PVL + SA in recurrent eye infections has not been studied.

This study aimed to detect and report frequency and recurrence of periorbital or orbital infections as additional symptoms of PVL + SA colonisation in children.

Methods

We conducted a retrospective cohort study of pediatric patients who were treated for PVL + SA skin and soft tissue infection in our in- and outpatient clinics in Berlin, Germany from January 2012 to January 2017. We identified cases with periorbital or orbital infections in the year prior to the first PVL + SA evidence. In these cases, we conducted follow-up interviews by phone to determine recurrence of symptoms after the completion of decolonisation procedures.

Results

Fifty pediatric patients (age range: one week to 17 years) were evaluated and treated for PVL + SA infections in the reported time period. 19 patients (38%) reported periorbital infection or conjunctivitis, with recurrent hordeola as the most frequent finding (n = 9; 18%). Reappearance of hordeola (n = 5) was associated with recurrence of skin and soft tissue infections and/or de novo detection of PVL + SA. No further hordeola or other eye infections occurred after successful decolonisation.

Conclusion

Our findings suggest a frequent involvement of periorbital skin in children with PVL + SA infections. Pediatric patients with recurrent periorbital infections might benefit from PVL + SA screening and consecutive decolonisation procedures.

Clinical Presentation and Bacteriology of Eyebrow Infections: The Massachusetts Eye and Ear Infirmary Experience (2008-2015)

PURPOSE

This study retrospectively reviews preseptal cellulitis and abscesses involving the eyebrow to elucidate the bacteriology and potential causative factors.

METHODS

A retrospective chart review was conducted to identify patients who had been diagnosed with preseptal cellulitis or abscess involving the eyebrow at the Massachusetts Eye and Ear Infirmary between 2008 and 2015. Demographic, clinical, and microbiological data were collected.

RESULTS

Eighty patients with eyebrow infections were identified, of whom 49 (61.3%) were female and 31 (38.7%) were male. The median age was 37 years (range 14-67 years). Eyebrow abscess was present in 54 cases (67.5%), while 26 cases (32.5%) were limited to preseptal cellulitis without abscess formation. Methicillin-resistant Staphylococcus aureus was found in 20 abscesses (39.2% of culture results), and methicillin-sensitive S. aureus was found in 12 abscesses (23.5% of culture results). Coagulase-negative staphylococci were present in 7 eyebrow abscesses (13.7% of culture results). Clinical history was remarkable for eyebrow hair removal (tweezing, waxing, threading, or shaving) in 17 cases (21.3%), manipulation of acne lesions ("popping," "picking," or "squeezing") in 6 cases (7.5%), and both brow hair removal and acne manipulation in 1 case (1.3%).

CONCLUSIONS

There is a high incidence of methicillin-resistant Staphylococcus aureus in the bacteriology of eyebrow infections. Empirical antibiotic coverage for methicillin-resistant Staphylococcus aureus should be strongly considered in any patient with an eyebrow area abscess or preseptal cellulitis. Individuals who practice cosmetic eyebrow grooming should be encouraged to consider hygiene practices, which could reduce the risk of infection.

Lacrimal gland abscess in children: Two case reports and literature review

Acute suppurative bacterial dacryoadenitis (ASBD) with abscess formation is rarely seen in clinical practice. A retrospective review of medical records in the past 8 years identified two unilateral cases in children, one developed presumably after methicillin-sensitive Staphylococcus aureus (MSSA) conjunctivitis and the other due to community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection. Computerized tomography scans showed globe indentation by the enlarged lacrimal glands with rim-enhancing lesions. After failing to respond to intravenous antibiotics, both abscesses resolved promptly with surgical drainage without any long-term sequelae.

A 10-Year Review of Ocular Methicillin-Resistant Staphylococcus aureus Infections: Epidemiology, Clinical Features, and Treatment

PURPOSE

To characterize epidemiological data on methicillin-resistant Staphylococcus aureus (MRSA) ocular infections over a 10-year period in Hong Kong; to compare the characteristics between hospital-associated methicillin-resistant Staphylococcus aureus (h-MRSA) and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) ocular infections; and to review the treatment regimen and outcome of identified cases.

METHODS

A retrospective case review of ocular samples testing positive for MRSA at a tertiary eye center from July 2005 to June 2015 was performed.

RESULTS

Ninety nonduplicative samples from 75 patients with ocular MRSA infection were included during the study period. The average annual rate of ocular MRSA infection among all ocular S. aureus infections was 12.9%. Ten patients had CA-MRSA (13.3%). The most common clinical manifestation was preseptal cellulitis in the CA-MRSA group and blepharoconjunctivitis in the h-MRSA group. Vision-threatening conditions occurred only in the h-MRSA group. Besides vancomycin, other antibiotics to which both MRSA groups were highly sensitive included chloramphenicol, fusidic acid, cotrimoxazole, and gentamicin. Significantly more CA-MRSA was sensitive to levofloxacin and clindamycin (P < 0.01). The h-MRSA group required a significantly longer duration of treatment to eradicate infection (mean 79 vs. 28 days, P < 0.01).

CONCLUSIONS

CA-MRSA presents as a genetically different organism with distinctive clinical presentation and antibiotic sensitivity from its h-MRSA counterpart. Despite increasing resistance patterns, we demonstrate that MRSA ocular infections can be effectively treated without the use of vancomycin, limiting its use to refractory or vision-threatening conditions.

Treatment of Staphylococcus aureus Infections

Staphylococcus aureus, although generally identified as a commensal, is also a common cause of human bacterial infections, including of the skin and other soft tissues, bones, bloodstream, and respiratory tract. The history of S. aureus treatment is marked by the development of resistance to each new class of antistaphylococcal antimicrobial drugs, including the penicillins, sulfonamides, tetracyclines, glycopeptides, and others, complicating therapy. S. aureus isolates identified in the 1960s were sometimes resistant to methicillin, a ß-lactam antimicrobial active initially against a majority S. aureus strains. These MRSA isolates, resistant to nearly all ß-lactam antimicrobials, were first largely confined to the health care environment and the patients who attended it. However, in the mid-1990s, new strains, known as community-associated (CA-) MRSA strains, emerged. CA-MRSA organisms, compared with health care-associated (HA-) MRSA strain types, are more often susceptible to multiple classes of non ß-lactam antimicrobials. While infections caused by methicillin-susceptible S. aureus (MSSA) strains are usually treated with drugs in the ß-lactam class, such as cephalosporins, oxacillin or nafcillin, MRSA infections are treated with drugs in other antimicrobial classes. The glycopeptide drug vancomycin, and in some countries teicoplanin, is the most common drug used to treat severe MRSA infections. There are now other classes of antimicrobials available to treat staphylococcal infections, including several that have been approved after 2009. The antimicrobial management of invasive and noninvasive S. aureus infections in the ambulatory and in-patient settings is the topic of this review. Also discussed are common adverse effects of antistaphylococcal antimicrobial agents, advantages of one agent over another for specific clinical syndromes, and the use of adjunctive therapies such as surgery and intravenous immunoglobulin. We have detailed considerations in the therapy of noninvasive and invasive S. aureus infections. This is followed by sections on specific clinical infectious syndromes including skin and soft tissue infections, bacteremia, endocarditis and intravascular infections, pneumonia, osteomyelitis and vertebral discitis, epidural abscess, septic arthritis, pyomyositis, mastitis, necrotizing fasciitis, orbital infections, endophthalmitis, parotitis, staphylococcal toxinoses, urogenital infections, and central nervous system infections.

Staphylococcus aureus and its Bearing on Ophthalmic Disease

PURPOSE

To review antibiotic resistance associated with S. aureus endophthalmitis and the virulence of S. aureus.

METHODS

Review of the current and prospective approaches for treating S. aureus endophthalmitis.

RESULTS

Bacterial endophthalmitis remains to be a major threat for vision. S. aureus endophthalmitis specifically, carries a poor visual prognosis making early diagnosis and treatment crucial. Methicillin resistant Staphylococcus aureus (MRSA) endophthalmitis represents a significant number of S. aureus endophthalmitis cases. MRSA with reduced susceptibility to glycopeptide antibiotics such as vancomycin (vancomycin intermediate S. aureus, VISA) have also emerged in the ocular infections, and there has been a rise in S. aureus resistance to new and old generation fluoroquinolones that are commonly used for prophylaxis after intravitreal injections and intraocular surgeries.

CONCLUSIONS

With the rise in the number of penetrating procedures in the ophthalmology practice and the parallel rise in antibiotic resistance, prophylaxis and awareness of the antimicrobial resistance profiles remain crucial and the identification of novel antimicrobials is essential.

Methicillin-Resistant Staphylococcus aureus Ocular Infection in Taiwan: Clinical Features, Genotying, and Antibiotic Susceptibility

Methicillin-resistant Staphylococcus aureus (MRSA) infection is an important public health issue. This observational study aimed to characterize clinical features, antibiotic susceptibility, and genotypes of ocular infections caused by MRSA based on the clinical and molecular definitions of community-associated (CA) and healthcare-associated (HA) strains.Fifty-nine patients with culture-proven S aureus ocular infection were enrolled from January 1, 2010 to December 31, 2011 at Chang Gung Memorial Hospital, Taiwan. Antibiotic susceptibility was verified using disk diffusion/E test. For characterization, staphylococcal cassette chromosome mec (SCCmec), pulsed-field gel electrophoresis (PFGE), multilocus sequence type (MLST), and Panton-Valentine leukocidin (PVL) gene, were performed. MRSA isolates from the patients with HA factors were classified as clinically defined HA-MRSA, and those carrying SCCmec type I to III as molecularly defined HA-MRSA.Thirty-four patients with MRSA ocular infection were identified. The most common clone of CA-MRSA and HA-MRSA isolates was ST59/PFGE type D/SCCmec IV,VT/PVL (+) (n = 12) and CC 239/PFGE type A/SCCmec III, IIIA/PVL(-) (n = 10), respectively. All the 11 patients with molecularly defined HA-MRSA infections and 50% of the 22 patients with molecularly defined CA-MRSA infections were found to have HA factors (P = .005). CA-MRSA tended to cause lid infections, whereas HA-MRSA tended to cause corneal infections. Contrary to HA-MRSA isolates, nearly all the CA-MRSA isolates were susceptible to trimethoprim/sulfamethoxazole and fluoroquinolones under either clinical or molecular classifications.In Taiwan, CA-MRSA isolates exhibited considerably higher susceptibility to fluoroquinolones when compared with HA-MRSA isolates. A strong correlation was observed between the HA factors and molecularly defined HA-MRSA isolates.

A Comparison of Clinical Features between Community-Associated and Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Keratitis

Purpose. To compare the clinical features of community-associated (CA) and healthcare-associated (HA) methicillin-resistant Staphylococcus aureus (MRSA) keratitis. Methods. Patients presenting with culture-proven MRSA keratitis between January 1, 2006, and December 31, 2010, at Chang Gung Memorial Hospital, Taiwan, were included in this study. The patients' demographic and clinical information were reviewed retrospectively. Antibiotic susceptibility was verified using the disk diffusion method. Results. Information on 26 patients with MRSA keratitis was collected, including 12 cases of CA-MRSA and 14 cases of HA-MRSA. All MRSA isolates were susceptible to vancomycin; the only difference in drug susceptibility was that CA-MRSA isolates were more susceptible to trimethoprim/sulfamethoxazole than HA-MRSA (P = .034). The most common risk factor for MRSA keratitis was ocular surface disease. No significant differences were observed between the 2 groups in terms of clinical features, treatments, and visual outcomes. Conclusion. In Taiwan, CA-MRSA rivals HA-MRSA as a critical cause of MRSA keratitis. Furthermore, CA-MRSA isolates are multidrug resistant. CA-MRSA and HA-MRSA keratitis are clinically indistinguishable, although larger studies are warranted to further evaluate this association.

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.

Screening and characterization of Staphylococcus aureus from ophthalmology clinic surfaces: a proposed surveillance tool

PURPOSE

To screen environmental surfaces of an outpatient ophthalmic clinic for methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA); to identify the most commonly contaminated surfaces and to phenotype and genotype all collected isolates.

DESIGN

A single institution, 1-year prospective environmental study.

METHODS

Commonly touched surfaces in examination rooms and common areas were targeted and sampled on a quarterly basis for 1 year. Samples were collected using electrostatic cloths and swabs. S. aureus was isolated using nonselective and selective media. Morphologic characteristics and standard biologic testing were used to confirm staphylococcal species. S. aureus isolates were phenotypically (Kirby-Bauer method) and genotypically characterized (mecA confirmation, SCCmec typing and pulsed-field gel electrophoresis). Dendrogram analysis was used to establish genetic relatedness between the isolates.

RESULTS

Of 112 total samples, 27 (24%) and 5 (4%) were MSSA- and MRSA-positive, respectively. Both community-associated (SCCmec IV, USA300) and hospital-associated (SCCmec II, USA100) MRSA isolates were found. No single surface remained consistently positive with the same isolate over time, and molecular analysis demonstrated high levels of diversity among isolates. Doorknobs, slit-lamp headrests and chinrests, and computer keyboards were commonly found to be contaminated.

CONCLUSIONS

The proposed surveillance protocol successfully allowed the detection of both MSSA and MRSA contaminating important high-touch surfaces in a representative ophthalmology clinic. Frequently contaminated surfaces must be targeted for routine cleaning and disinfection because there is a constant introduction of clones over time. Hence, other clinics may consider implementing and adapting surveillance tools, like the one described here, to help them control these important nosocomial pathogens.

Survey of policy for MRSA screening in English cataract surgical units and changes to practice after updated National guidelines

Background

National guidelines on MRSA (methicillin-resistant Staphylococcus aureus) screening policy in England have changed on a number of occasions, but there is limited data on its influence at a local level. The aim of this study was to determine if changes in National policy influenced preoperative screening of cataract patients for MRSA.

Methods

A structured telephone survey was conducted on all 133 ophthalmology units in England in 2004 and again in 2007 for the initial responders, after a change in national policy.

Results

A total of 74 units (56%) responded in 2004 and 71 units (96% of initial respondents) in 2007. In 2004, 57% of units screened for MRSA. They screened groups at high risk of carriage, including patients with previous MRSA (93%) and patients from Nursing homes (21%). Swab sites included the nose (100%), eyes (31%) and perineum (62%). In 2007, there was no significant change in the number of units that screened for MRSA (57% vs 66%; p = 0.118; McNemar test). However, more units screened for MRSA in patients from nursing/residential homes (21% vs 51%; p = 0.004, McNemar test), and in patients who had recent admission to hospital (12% vs 36%; p = 0.003). In the second survey, 3 units (6%) now screened patients who were close relatives of MRSA carriers.

Conclusion

This survey has highlighted inconsistences in MRSA screening practice of day-case cataract surgery patients across England after 2 major national policy changes. A change in DoH policy only led to more units screening patients for MRSA from high risk groups.

Staphylococcus aureus corneal infections: effect of the Panton-Valentine leukocidin (PVL) and antibody to PVL on virulence and pathology

PURPOSE

Community-associated methicillin-resistant Staphylococcus aureus strains expressing Panton-Valentine leukocidin (PVL) are associated with severe skin and soft tissue infections, necrotizing pneumonia, and eye infections. We determined PVL's toxicity on infected mouse and cultured human corneal epithelial cells and the role of PVL and antibody to PVL in pathogenesis of murine keratitis.

METHODS

Cytotoxicity on corneas and corneal epithelial cells was evaluated by LDH assays. Scratched corneas of female A/J mice were inoculated with approximately 10⁷ CFU/eye of either WT S. aureus, isogenic ΔPVL, or strains overproducing PVL. Antibodies to PVL or control sera were topically applied to infected corneas 0, 24, and 32 hours postinfection, corneas scored for pathology and tissue levels of S. aureus were determined.

RESULTS

PVL expression augmented the cytotoxicity of S. aureus on infected mouse corneas and human cultured corneal epithelial cells. Variable effects on leukocyte recruitment, pathogenesis, and immunity were obtained in the in vivo studies. Inactivation of PVL in USA300 strains caused reduced pathology and bacterial counts. Results were variable when comparing WT and ΔPVL USA400 strains, while USA400 strains overproducing PVL caused increased bacterial burdens. Topical treatment with polyclonal antibody to PVL yielded significant reductions in corneal pathology and bacterial CFU in corneas infected with USA300 strains, whereas effects were inconsistent in eyes infected with USA400 strains.

CONCLUSIONS

PVL enhanced the virulence of a subset of MRSA strains in a keratitis model. Coupled with a variable effect of antibody treatment, it appears that PVL plays an inconsistent role in pathogenesis and immunity to S. aureus corneal infection.

Trends in ophthalmic manifestations of methicillin-resistant Staphylococcus aureus (MRSA) in a northern California pediatric population

PURPOSE

To determine pediatric clinical trends of ocular and periocular methicillin-resistant Staphylococcus aureus (MRSA) in a large northern California healthcare system.

METHODS

This study was a retrospective cross-sectional review of all pediatric cases (aged 0-18) with culture-positive ophthalmic MRSA isolates identified between January 2002 and December 2009. Medical record review included history, presentation, infection site, acquisition (community or nosocomial), antibiotic sensitivity/resistance, treatment, and clinical outcome. Incidence was classified by year, sex, and age. Parameters were analyzed for statistical significance by trend and χ(2) analysis.

RESULTS

A total of 399 ocular and periocular MRSA cases were included. Cases trended upward from 2002 to 2009, peaking in 2006. Of the 137 pediatric cases (0-18 years), 58% were community acquired. Conjunctivitis was the predominant presentation (40%), followed by stye/chalazion (25%), orbital cellulitis/abscess (19%), dacryocystitis (11%) and brow abscess (3%). Significant predictors for ocular infection with MRSA included male sex (61%), neonates (38%), and multiple infection sites on the body (38%). Resistance was high to bacitracin (80.9%) and ofloxacin (48.3%) but remained low for trimethoprim/sulfamethoxazole (8.7%). Topical therapy was effective in 29% of cases; oral antibiotics, in 47%. Intravenous therapy was required in 12% of cases and incision/drainage or surgery in 19%. Initial oral antibiotic treatment, primarily cephalosporins (24%), was ineffective in 37% of patients. There was a significant increase in resistance to antibiotic therapy (P < 0.001) during the study period. No patients developed permanent visual impairment.

CONCLUSIONS

Pediatric ocular and periocular MRSA is increasing in incidence and resistance in our patient population. Outcomes can be improved by early recognition, proper antibiotic selection, and obtaining cultures and sensitivities when resistant or severe ocular infections are present.

Staphylococcus aureus ocular infection: methicillin-resistance, clinical features, and antibiotic susceptibilities

Background

Methicillin-resistant Staphylococcus aureus (MRSA) infection is an important public health issue. The study aimed to determine the prevalence of ocular infections caused by MRSA and to identify the clinical characteristics and antibiotic susceptibility of ocular MRSA infections by comparing those of ocular methicillin-sensitive S. aureus (MSSA) infections.

Methodology/Principal Findings

The medical records of the patients (n = 519) with culture-proven S. aureus ocular infections seen between January 1, 1999 and December 31, 2008 in Chang Gung Memorial Hospital were retrospectively reviewed. Two hundred and seventy-four patients with MRSA and 245 with MSSA ocular infections were identified. The average rate of MRSA in S. aureus infections was 52.8% and the trend was stable over the ten years (P value for trend  = 0.228). MRSA ocular infections were significantly more common among the patients with healthcare exposure (P = 0.024), but 66.1% (181/274) patients with MRSA ocular infections had no healthcare exposure. The most common clinical presentation for both MRSA and MSSA ocular infections was keratitis; MRSA and MSSA caused a similar disease spectrum except for lid infections. MRSA was significantly more resistant than MSSA to clindamycin, erythromycin and sulfamethoxazole/trimethoprim (all P<0.001).

Conclusions/significance

We demonstrated a paralleled trend of ocular MRSA infection in a highly prevalent MRSA country by hospital-based survey. Except for lid disorder, MRSA shared similar spectrum of ocular pathology with MSSA. Since S. aureus is a common ocular pathogen, our results raise clinician’s attention to the existence of highly prevalent MRSA.

Staphylococcus aureus eye infections in two Indian hospitals: emergence of ST772 as a major clone

Purpose

The purpose of this study was to perform molecular characterization of Staphylococcus aureus isolates causing a variety of eye infections from two major eye care hospitals in India.

Methods

Twenty-four isolates from Aravind Eye Hospital, Madurai, India, and nine isolates from LV Prasad Eye Institute, Bhubaneswar, India, representing severe to nonsevere eye infections like microbial keratitis to lacrimal sac abscess, were characterized. Staphylococcal cassette chromosome mec typing, multilocus sequence typing, accessory gene regulator typing, staphylococcal protein A typing, and pulsed field gel electrophoresis were used, along with determination of the presence of Panton–Valentine leucocidin toxin and endotoxin gene cluster among each sequence type.

Results

The majority of eye infections, both severe and nonsevere, were caused by sequence type (ST)772, positive for the Panton–Valentine leucocidin gene, and carrying methicillin-resistant staphylococcal cassette chromosome mec type V cassette (22/33, 67%). Some of the other sequence types that caused severe eye infections were ST1 (9%), 5 (3%), 72 (6%), 88 (3%), 121 (3%), and 672 (3%). This is the first report of the presence of ST1 and 88 in India.

Conclusion

Although the number of isolates included in this study was small, most of the eye infections were caused by community-associated S. aureus where patients had no history of hospitalization or treatment in the past year. In the case of six severe infections, patients were admitted for surgeries and there is probability of hospital infection. In addition, only methicillin-resistant S. aureus isolates carrying staphylococcal cassette chromosome mec type V were detected. Epidemic methicillin-resistant Staphylococcus aureus 15 (ST22) is a major ST found in health care as well as community settings in non-eye infections in India, but only one methicillin-sensitive S. aureus isolate belonging to ST22 was detected. Predominantly ST772, along with a few other STs, caused the 33 eye infections studied.

Methicillin-resistant Staphylococcus aureus ocular infection: a 10-year hospital-based study

PURPOSE

To characterize the patient demographics, clinical features, and antibiotic susceptibility of ocular infections caused by methicillin-resistant Staphylococcus aureus (MRSA), including community-associated (CA) and healthcare-associated (HA) isolates.

DESIGN

Retrospective, observational study.

PARTICIPANTS

Patients (n = 519) with culture-proven S. aureus ocular infections seen between January 1, 1999, and December 31, 2008, in Chang Gung Memorial Hospital.

METHODS

Data collected included patient demographics and clinical information. Antibiotic susceptibility was verified by disc diffusion method.

MAIN OUTCOME MEASURES

Proportion of MRSA in S. aureus ocular infections and the clinical characteristics, diagnoses, and antibiotic susceptibility patterns of CA-MRSA versus HA-MRSA ocular infections.

RESULTS

We identified 274 patients with MRSA ocular infections, which comprised 181 CA-MRSA and 93 HA-MRSA isolates. The average rate of MRSA in S. aureus infections was 52.8% with a stable trend, whereas the annual ratio of CA-MRSA in ocular MRSA infections averaged 66.1% and tended to increase over the 10-year interval. Patients with ocular CA-MRSA were younger. Lid and lacrimal system disorders were more common, but keratitis, endophthalmitis, and wound infection were less common among CA-MRSA cases than HA-MRSA cases. Both CA-MRSA and HA-MRSA isolates were resistant to clindamycin and erythromycin, but CA-MRSA was more susceptible to sulfamethoxazole/trimethoprim.

CONCLUSIONS

Community-associated MRSA is an important pathogen of ocular infections; CA-MRSA and HA-MRSA ocular infections differ demographically and clinically, but both strains were multi-resistant in Chang Gung Memorial Hospital, one of the biggest referral centers in Taiwan. In a country with a high prevalence of MRSA, ophthalmologists should be aware of such epidemiologic information.

Role of wall teichoic acids in Staphylococcus aureus endophthalmitis

PURPOSE

Wall teichoic acids (WTAs) are major polyanionic polymer components of the cell wall of Staphylococcus aureus. However, little is known about their role at the host-pathogen interface, especially in endophthalmitis. This study was designed to investigate the extent to which WTAs contribute to the pathogenicity of S. aureus in models of endophthalmitis and to determine whether there would be value in targeting their biosynthesis as a new therapeutic approach.

METHODS

S. aureus RN6390 and its isogenic WTA-null mutant (RN6390ΔtarO) were used to evaluate the role of WTAs in endophthalmitis. RN6390 and RN6390ΔtarO were cultured in bovine vitreous humor (VH) in vitro or inoculated into the vitreous chamber of C57B6 mice. Changes in the number of bacteria, organ function as determined by electroretinography (ERG), and histopathologic changes were assessed throughout the course of infection. In addition, the efficacy of WTA biosynthesis inhibitors in VH in vitro was examined.

RESULTS

It was observed that a component of VH synergized with WTA biosynthesis inhibitors in vitro and killed the S. aureus. This effect was also seen when mutants incapable of expressing WTA were exposed to VH. The killing activity of VH was lost on treatment with a protease inhibitor. RN6390ΔtarO could not survive in mouse eyes and did not affect organ function, nor was it able to establish endophthalmitis.

CONCLUSIONS

WTAs are essential cellular constituents for the manifestation of virulence by S. aureus in endophthalmitis, and appears to be a viable target for treating the endophthalmitis caused by S. aureus strains.

Endogenous methicillin-resistant Staphylococcus aureus endophthalmitis

PURPOSE

To report on the presentation, treatment, and outcomes of the largest series to date for patients with endogenous methicillin-resistant Staphylococcus aureus endophthalmitis at a single institution and compare the results from previously published reports of this disease entity.

METHODS

Retrospective, noncomparative, consecutive case series of patients who were treated for endogenous methicillin-resistant S. aureus endophthalmitis from a single tertiary referral institution were reviewed.

RESULTS

Eight eyes of seven consecutive patients, with a mean age of 58.1 years, were diagnosed with culture-proven endogenous methicillin-resistant S. aureus endophthalmitis. Five patients were male, and six patients had a unilateral presentation. Five of eight eyes were treated with initial vitreous tap and injection of antibiotics, and six eyes showed a retinal detachment during the course of treatment. Final visual acuity ranged from 20/40 to no light perception, and 5 of 8 eyes showed improvement in visual acuity from initial presentation. Only one eye became blind and painful and required enucleation.

CONCLUSION

This series represents the largest single-institution report on endogenous methicillin-resistant S. aureus endophthalmitis and associated outcomes. Although previously reported cases cited poor visual outcomes and high enucleation rates, the authors' current series shows that retinal detachments are common and enucleation rates are low.

Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children: executive summary

Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.

Presence of adequate intravitreal concentrations of daptomycin after systemic intravenous administration in a patient with endogenous endophthalmitis

STUDY OBJECTIVE

To determine whether daptomycin has the potential to be an effective alternative treatment to vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) endogenous endophthalmitis by measuring daptomycin penetration into the vitreous humor.

DESIGN

Laboratory analysis of serum and intravitreal fluids to quantify the ratio between vitreous humor and serum daptomycin concentrations.

SETTING

Critical care unit in a university-affiliated tertiary care medical center.

PATIENT

A 53-year-old woman treated with intravenous daptomycin for MRSA bacteremia, endophthalmitis, and pericarditis.

MEASUREMENTS AND MAIN RESULTS

After the first dose of intravenous daptomycin 10 mg/kg was administered to the patient, serum and intravitreal fluids were analyzed by using high-performance liquid chromatography to determine daptomycin concentrations; pericardial fluid was also analyzed to determine whether adequate levels were present in actively infected tissue. A vitreous concentration of approximately 28% of the serum concentration was achieved. Although therapeutic efficacy could not be assessed in the absence of intraocular cultures, the presence of adequate drug concentrations in the vitreous humor is promising. Ophthalmic infections caused by resistant isolates continue to increase, and effective alternatives to vancomycin, the standard of care, are needed. For endogenous endophthalmitis, these alternative therapies will need to reach therapeutic concentrations in the vitreous humor and adequately penetrate the terminal source of infection. In this analysis, the intravitreal concentration of daptomycin was comparable to concentrations previously reported with vancomycin; thus daptomcyin may be an attractive option when vancomycin therapy fails or is contraindicated. To our knowledge, this is the first report of intravitreal daptomycin concentrations measured in a patient receiving intravenous daptomycin.

CONCLUSION

Adequate concentrations of daptomycin were achieved in the vitreous fluid after a single systemic dose of the drug. Daptomycin may be an effective alternative to vancomycin in patients with ophthalmic infections. Future clinical studies comparing daptomycin with vancomycin in this clinical setting are warranted.

Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children

Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.

Molecular epidemiology of methicillin-resistant and methicillin-susceptible Staphylococcus aureus isolated from the eye

PURPOSE

Methicillin-resistant Staphylococcus aureus (MRSA) strains are commonly classified as hospital-acquired (HA) or community-acquired (CA). Typical HA-MRSA isolates are characterized by multidrug resistance and the SCCmec type II cassette, while CA-MRSA isolates are generally susceptible to more drug classes, are often of SCCmec type IV, and frequently carry the Panton-Valentine leukocidin (PVL) genes. This study determined the presence of traits characteristic for CA and HA strains in ocular MRSA isolates.

MATERIALS AND METHODS

Fifty-six recent ocular isolates, consisting of 40 MRSA and 16 methicillin-susceptible Staphylococcus aureus (MSSA) comparator strains, were characterized. Minimum inhibitory concentration (MIC) testing was done according to current Clinical and Laboratory Standards Institute guidelines. Detection of the PVL encoding genes and determination of the SCCmec type was done by polymerase chain reaction (PCR), while spa typing and cluster analysis was performed following DNA sequencing.

RESULTS

Of the 38 typeable MRSA isolates, 22 were of SCCmec type II and 16 were of SCCmec type IV. All SCCmec type II isolates were multidrug-resistant, lacked the PVL genes, and were of spa type t002 or closely related spa types. In contrast, the SCCmec type IV isolates were resistant to fewer classes of antimicrobial agents, often possessed the PVL genes (75.0%), and were of spa type t008 or closely related spa types.

CONCLUSIONS

While the majority of ocular MRSA strains in this study fit the classical profile of HA- and CA-MRSA, some CA-MRSA isolates exhibited higher levels of antimicrobial resistance, which should be of particular concern to eye-care professionals. Furthermore, the apparent association of spa types and SCCmec types observed here warrants further investigation and suggests that spa typing may be useful in future HA- and CA-MRSA characterization studies.

Methicillin resistance of Staphylococcus species among health care and nonhealth care workers undergoing cataract surgery

Purpose:

The purpose of this study is to characterize the bacterial flora of the ocular and periocular surface in cataract surgery patients and to determine the prevalence of methicillin resistance among staphylococcal isolates obtained from health care workers (HCWs) and non-HCWs.

Methods:

In this prospective, multicenter, case series study, eyelid and conjunctival cultures were obtained from the nonoperative eye of 399 consecutive cataract patients on the day of surgery prior to application of topical anesthetics, antibiotics, or antiseptics. Speciation and susceptibility testing were performed at the Dean A. McGee Eye Institute. Logistic regression was utilized to evaluate whether any factors were significant in predicting the presence of methicillin-resistant staphylococcal isolates.

Results:

Staphylococcus epidermidis (62.9%), followed by S. aureus (14.0%), was the most frequently isolated organism. Methicillin-resistant S. epidermidis accounted for 47.1% (178/378) of S. epidermidis isolates, and methicillin-resistant S. aureus accounted for 29.5% (26/88) of S. aureus isolates. Methicillin-resistant staphylococcal isolates were found in 157 of 399 (39.3%) patients, the majority (89.2%) of whom were non-HCWs. The likelihood of being colonized with methicillin-resistant organisms increased with age (odds ratio [OR], 1.27; 95% confidence interval [CI]: 1.02–1.58; P = 0.04) but decreased with diabetes (OR, 0.51; 95% CI: 0.29–0.89; P = 0.02). Being a HCW (OR, 1.25; 95% CI: 0.61–2.58; P = 0.54) was not a risk factor for colonization with methicillin-resistant organisms.

Conclusion:

Patients without exposure to health care environments are as likely as HCWs to be colonized with methicillin-resistant organisms. Increasing methicillin resistance with age may partially explain the increased risk of endophthalmitis reported with older age.

[Multiresistant bacteria in ophthalmology]

Multidrug-resistant bacteria have emerged as an increasing threat in many areas of medicine. The most prominent multidrug-resistant pathogens are methicillin-resistant S. aureus (MRSA), vancomycin-resistant MRSA (VMRSA), vancomycin-resistant enterococci (VRE), and Enterobacteriaceae with extended-spectrum beta-lactamase (ESBL). In particular, MRSA and VRE cause infections seen in ophthalmology. The lids, lacrimal duct, and ocular surface are frequently involved.

Scanning electron microscopy visualization of methicillin-resistant Staphylococcus aureus after contact with gatifloxacin with and without preservative

PURPOSE

To test a visual model by looking at the differences in effect of Zymar((R)) (gatifloxacin plus benzalkonium chloride [BAK]) when compared to gatifloxacin and a normal saline (NS) control upon a methicillin and gatifloxacin-resistant Staphylococcus aureus (MRSA) species.

METHODS

An ocular isolate of gatifloxacin-resistant (minimal inhibitory concentration >2 to 4 microg/mL) MRSA was grown to confluency. Chambered slides were prepared with bacterial culture smears, and then incubated with either gatifloxacin at the concentrations of 1 and 10 microg/mL, Zymar containing equivalent concentrations of gatifloxacin, or NS. Bacterial cultures were fixed after 10, 30, and 60 min. Fixed slides were coated in gold sputter for examination. Bacteria were visually evaluated with scanning electron microscopy (SEM) at 50,000x. Blinded review of SEM images compared structural changes and mitotic activity across samples.

RESULTS

MRSA exposed to 10 microg Zymar for 60 min showed significantly greater pleomorphism and cell wall surface changes when compared to gatifloxacin (P < 0.0001) and NS (P = 0.001), and significantly less mitotic activity than NS (P = 0.002).

CONCLUSION

Using SEM, the topical formulation of gatifloxacin 0.3% (Zymar), which contains BAK, had greater antibacterial activity than did gatifloxacin alone in gatifloxacin and methicillin-resistant S. aureus, thereby illustrating potential advantages of the preservative in the commercial formulation. We further show that these effects can be visualized and quantified.

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.

Community-associated meticillin-resistant Staphylococcus aureus infections: epidemiology, recognition and management

Meticillin-resistant Staphylococcus aureus (MRSA) is an important cause of infection, particularly in hospitalized patients and those with significant healthcare exposure. In recent years, epidemic community-associated MRSA (CA-MRSA) infections occurring in patients without healthcare risk factors have become more frequent. The most common manifestation of CA-MRSA infection is skin and soft tissue infection, although necrotizing pneumonia, sepsis and osteoarticular infections can occur. CA-MRSA strains have become endemic in many communities and are genetically distinct from previously identified MRSA strains. CA-MRSA may be more capable colonizers of humans and more virulent than other S. aureus strains. Specific mechanisms of pathogenicity have not been elucidated, but several factors have been proposed as responsible for the virulence of CA-MRSA, including the Panton-Valentine leukocidin, phenol-soluble modulins and type I arginine catabolic mobile element. The movement of CA-MRSA strains into the nosocomial setting limits the utility of using clinical risk factors alone to designate community- or healthcare-associated status. Identification of unique genetic characteristics and genotyping are valuable tools for MRSA epidemiological studies. Although the optimum pharmacological therapy for CA-MRSA infections has not been determined, many CA-MRSA strains remain broadly susceptible to several non-beta-lactam antibacterial agents. Empirical antibacterial therapy should include an MRSA-active agent, particularly in areas where CA-MRSA is endemic.

Waves of resistance: Staphylococcus aureus in the antibiotic era

Staphylococcus aureus is notorious for its ability to become resistant to antibiotics. Infections that are caused by antibiotic-resistant strains often occur in epidemic waves that are initiated by one or a few successful clones. Methicillin-resistant S. aureus (MRSA) features prominently in these epidemics. Historically associated with hospitals and other health care settings, MRSA has now emerged as a widespread cause of community infections. Community or community-associated MRSA (CA-MRSA) can spread rapidly among healthy individuals. Outbreaks of CA-MRSA infections have been reported worldwide, and CA-MRSA strains are now epidemic in the United States. Here, we review the molecular epidemiology of the epidemic waves of penicillin- and methicillin-resistant strains of S. aureus that have occurred since 1940, with a focus on the clinical and molecular epidemiology of CA-MRSA.

Endogenous endophthalmitis caused by methicillin-resistant Staphylococcus aureus (MRSA)

PURPOSE

To report clinical features, diagnostic features, and outcome in three patients presenting with fulminant endogenous endophthalmitis caused by methicillin-resistant Staphylococcus aureus.

METHODS

Retrospective review of clinical data and microbiological findings in three cases.

RESULTS

All three patients had predisposing conditions for endogenous endophthalmitis (B-cell lymphoma, diabetes mellitus, steroid therapy, or gastrointestinal symptoms, such as vomiting and diarrhea). Two patients were colonized by methicillin-resistant Staphylococcus aureus in typical sites (nose, groin, throat, and conjunctiva), whereas one patient who developed phlebitis at the infusion puncture site followed by bacteremia presented no typical colonization. Despite adequate therapy, two patients lost visual function in the infected eye, one of which had to be enucleated. The other patient's eye regained adequate function.

CONCLUSION

Endogenous endophthalmitis by methicillin-resistant Staphylococcus aureus is a rare but serious condition. Early and specific therapy based on reliable detection of the underlying microorganism may help in preventing loss of visual function.

Trimethoprim-sulfamethoxazole for methicillin-resistant Staphylococcus aureus: a forgotten alternative?

Methicillin-resistant Staphylococcus aureus (MRSA) is a growing infectious concern, mainly in the context of its rapid adaptation to novel antibiotic options for its treatment and the growing morbidity, mortality, and healthcare costs associated with its emergence. the authors sought to investigate whether an older antibiotic, such as trimethoprim-sulfamethoxazole (SXT), may have a role in treating MRSA-related infections, according to the available literature on the subject. The authors reviewed literature data on: resistance of MRSA to SXT worldwide in recent years, efficacy of SXT for MRSA decolonization or prophylaxis from MRSA infections, and clinical therapeutic efficacy of SXT in treating mild or severe community-acquired or hospital-acquired MRSA infections. Resistance varies worldwide, in general being low in the industrialized world and higher in developing countries. SXT is one of the numerous understudied options for MRSA decolonization and is growingly recognized as potentially effective in preventing MRSA infections in certain settings. Limited data on its therapeutic efficacy are encouraging, at least for mild, community-acquired infections. SXT may represent a cost-effective alternative weapon against MRSA. Its utility against this increasingly threatening pathogen need clarification through further clinical trials.

Vertically acquired community methicillin-resistant Staphylococcus aureus dacryocystitis in a neonate

Methicillin-resistant Staphylococcus aureus (MRSA) infections are becoming increasingly common in the community, especially among children.(1) Community MRSA differs from the more familiar nosocomial MRSA in having a distinct epidemiology and a broader antibiotic-susceptibility profile.(2) Community MRSA can infect the eye and orbit.(3,4) Cases have been reported in otherwise-healthy children, including chronic dacryocystitis in an 8-month-old infant and orbital cellulitis in a 16-month-old child.(5,6) I report a case of perinatally acquired community MRSA dacryocystitis and periorbital cellulitis associated with bacteremia in a 12-day-old previously healthy, full-term neonate.

[Eyelid necrosis caused by an hymenopteran insect bite]

We report a case report of extensive eyelid necrosis caused by an insect bite. A 39-year-old man had suffered ocular trauma from a hymenopteran insect in Tunisia. The patient presented with eyelid necrosis. Eyelid necrosis mechanisms following insect bites are discussed and other causes of eyelid necrosis are presented. Eyelid necrosis, often caused by vasoconstrictive medications or animal venoms, notably hymenopteran insect bites, can result in substantial eyelid injury.

Increasing prevalence of methicillin resistance in serious ocular infections caused by Staphylococcus aureus in the United States: 2000 to 2005

PURPOSE

To report the nationwide prevalence of methicillin resistance in serious ocular infections involving Staphylococcus aureus and profile in vitro antimicrobial susceptibility of S aureus from ocular isolates over time.

SETTING

Mount Sinai School of Medicine, New York, New York, USA.

METHODS

Data on S aureus submitted to The Surveillance Network (TSN) by more than 200 laboratories in the United States from January 2000 to December 2005 were reviewed. The prevalence of methicillin resistance in S aureus ocular infections and in vitro susceptibility to antibiotic agents commonly used to treat or prevent ocular infections were determined.

RESULTS

The proportion of S aureus infections culture-positive for methicillin-resistant S aureus (MRSA) increased from 29.5% in 2000 to 41.6% in 2005. The MRSA ocular isolates were multidrug resistant; that is, in vitro resistance to 3 antibiotic agents or more, including all fluoroquinolones tested.

CONCLUSIONS

Multidrug-resistant MRSA is increasing in serious ocular infections. Based on the rate of increase in the TSN database, MRSA cultures from serious ocular infections could be more common than methicillin-susceptible S aureus within 2 to 3 years. Large-scale national surveillance programs are needed to monitor in vitro antimicrobial resistance trends in ocular isolates.

Postantibiotic effects and bactericidal activities of levofloxacin and gatifloxacin at concentrations simulating those of topical ophthalmic administration against fluoroquinolone-resistant and fluoroquinolone-sensitive methicillin-resistant Staphylococcus aureus strains

The bactericidal activities and postantibiotic effects (PAEs) of levofloxacin and gatifloxacin at concentrations corresponding to those in antibiotic eye drops against methicillin-resistant Staphylococcus aureus strains were determined. Levofloxacin and gatifloxacin at concentrations simulating those in eye drops showed lower bactericidal activities and shorter PAEs against fluoroquinolone-resistant strains than against fluoroquinolone-sensitive strains.

Dacryoadenitis caused by methicillin-resistant Staphylococcus aureus

A healthy 23-year-old man developed swelling of his left upper eyelid, conjunctival chemosis, and ocular motility restriction associated with epiphora and purulent discharge from the lacrimal ductules. Clinical examination, imaging, and culture results disclosed dacryoadenitis caused by community-acquired methicillin-resistant Staphylococcus aureus. To our knowledge, this is the first reported case of methicillin-resistant S. aureus-associated dacryoadenitis.

Visual outcome and bacterial sensitivity after methicillin-resistant Staphylococcus aureus-associated acute endophthalmitis

PURPOSE

To determine the frequency, visual outcome, and bacterial sensitivity in cases of methicillin-resistant Staphylococcus aureus (MRSA)-associated acute postoperative endophthalmitis occurring after cataract surgery.

DESIGN

Retrospective, consecutive, observational case series.

METHODS

Sixty-four cases of acute endophthalmitis occurring within six weeks after cataract surgery were identified over a three-year interval at a single vitreoretinal practice. Cases related to MRSA were studied and visual outcomes and bacterial sensitivities were recorded.

RESULTS

Thirty-three of the 64 eyes were culture positive, and six of the 33 cases (18.2%) demonstrated MRSA infection. All six eyes were started on fluoroquinolone antibiotics two or three days before surgery. Corneal abnormalities were noted in five of the six cases (83.3%), ranging from wound infection to diffuse corneal opacification. Visual acuity at last follow-up was no light perception (NLP) in two eyes, hand movements in two eyes, and 20/30 or better in two eyes. One eye with NLP vision underwent enucleation within three days of presentation because of panophthalmitis and impending sepsis. All six organisms were sensitive in vitro to both gentamicin and vancomycin. No organism was sensitive to any fluoroquinolone antibiotic, although not all organisms were tested against all fluoroquinolones.

CONCLUSIONS

MRSA infection accounts for 18% of culture-positive cases of endophthalmitis in this study and was associated with a poor visual outcome in two-thirds of our patients. MRSA organisms may be resistant in vitro to all generations of fluoroquinolone antibiotics, but do seem to be sensitive to gentamicin and vancomycin. The incidence of MRSA endophthalmitis seems to have increased significantly since the Endophthalmitis Vitrectomy Study was published in 1996.

Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA)--a rare cause of fulminant orbital cellulitis

We report a 55-year-old female patient who developed a severe right-sided orbital cellulitis. Past history was significant for a boil on the right upper eyelid 2 days prior. Visual acuity at presentation was perception of light with inaccurate projection. Orbital computed tomography (CT) scan and routine blood investigations, including blood culture, urine examination, and urine culture, were performed. CT scan showed a superonasal orbital mass suggestive of an abscess. Abscess drainage followed by pus culture, sensitivity, and pulsed-field gel electrophoresis revealed community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) resistant to all antibiotics except vancomycin, cotrimoxazole, and amikacin. The condition completely resolved post antibiotic and steroid therapy. At 3 months follow-up, the vision in the right eye was 6/9. We report this case to highlight CAMRSA as a rare but virulent cause of orbital cellulitis; empiric antibiotic therapy should include coverage for CAMRSA until susceptibilities come back.

Periocular infection

PURPOSE OF REVIEW

The aim of this article is to acquaint the clinician with advances in the diagnosis and management of periocular cellulitis and to alert physicians to emerging pathogens.

RECENT FINDINGS

The most important, recent infectious disease entity to consider is community-acquired methicillin-resistant Staphylococcus aureus, which is emerging as a significant problem across the country. The potential devastation caused by necrotizing fasciitis is also reviewed, since this diagnosis is easily missed early in its course. A variety of less common and frankly atypical pathogens is presented to remind the clinician that, on occasion, the hoofbeats are indeed a zebra's.

SUMMARY

Periocular cellulitis remains an important and common entity in ophthalmology. The emergence of new pathogens and the resistance to conventional treatment by others are a cause for concern and require an understanding of management strategies.