Infections of the eye

Listeria Monocytogenes-Induced Endogenous Endophthalmitis in an Otherwise Healthy Individual: Rapid PCR-Diagnosis as the Basis for Effective Treatment

Purpose

Listeria monocytogenes is a rare cause of endogenous endophthalmitis. To date 15 cases have been published in the literature. All eyes showed similar clinical features and profound visual loss mainly due to delayed diagnosis.

Methods

An additional case of an otherwise healthy 73 year-old male, who was referred to our hospital because of acute iridocyclitis with secondary glaucoma, is reported. Within a few days the severity of the intraocular infection increased dramatically, resulting in the clinical picture of acute endophthalmitis.

Results

In contrast to most published cases, early identification of the causative pathogen in the aqueous humor after anterior chamber puncture using polymerase chain reaction (PCR) and the initiation of a specific, systemic antibiotic medication, resulted in complete recovery of visual acuity.

Conclusions

PCR is very useful for the identification of the pathogen in intraocular infections.

The prevalence of adenoviral conjunctivitis at the Clinical Hospital of the State University of Campinas, Brazil

OBJECTIVES

Viral conjunctivitis is a common, highly contagious disease that is often caused by an adenovirus. The aim of this study was to evaluate the prevalence of adenoviral conjunctivitis by analyzing data from a prospective clinical study of 122 consecutively enrolled patients who were treated at the Clinical Hospital of the State University of Campinas (UNICAMP) after a clinical diagnosis of infectious conjunctivitis between November 2011 and June 2012.

METHODS

Polymerase chain reaction was used to evaluate all cases of clinically diagnosed infectious conjunctivitis and based on the laboratory findings, the prevalence of adenoviral infections was determined. The incidence of subepithelial corneal infiltrates was also investigated.

RESULTS

Of the 122 patients with acute infectious conjunctivitis included, 72 had positive polymerase chain reaction results for adenoviruses and 17 patients developed subepithelial corneal infiltrates (13.93%).

CONCLUSIONS

The polymerase chain reaction revealed that the prevalence of adenoviral conjunctivitis was 59% in all patients who presented with a clinical diagnosis of infectious conjunctivitis from November 2011 to June 2012. The prevalence of adenoviral conjunctivitis in the study population was similar to its prevalence in other regions of the world.

In vitro evidence of involvement of the epithelial y+ transporter in β-defensin production on the ocular surface

To analyse the hypothesis as to whether there is a functional relationship between human cationic amino acid transporters (hCATs, y(+) transporter, the main transporter of L-arginine and L-lysine) and human β-defensin (important components of immune function) production on the ocular surface, arginase and nitrate monoxide synthase (NOS), enzymes that compete for L-arginine, were inhibited by norNOHA (N(omega)-hydroxy-nor-L-arginine) and/or L-NAME (NG-nitro-L-arginine methyl ester) in cultured human corneal epithelial cells. In addition, the transport activity of hCAT proteins was inhibited or activated through α-tocopherol or PMA (phorbol myristate acetate), respectively. Concentrations of the human inducible β-defensins (hBD) 2 and 3 were determined by ELISA experiments. The basic expression of hBD3 in non-stimulated HCE cells significantly exceeded that of hBD2. Both β-defensins also differed as to how readily their excretion could be stimulated. HBD2 excretion rate was 3.5 time more by L-NAME, whereas norNOHA had no effect. In contrast, hBD3 excretion was increased by norNOHA by a factor of 1.5 but L-NAME alone had no effect. The excretion of both β-defensins was increased 3- and 6-fold by combined administration of L-NAME, norNOHA and interleukin (IL)-1β. Administration of α-tocopherol increased hBD2 excretion twofold. No effect was observed for hBD3. With PMA, on the other hand, a reduction in secretion for both β-defensins was observed. These in vitro findings provide evidence of a functional association between CAT proteins and β-defensins 2 and 3 opening up a new field of research with pharmacological perspectives for treatment of inflammatory diseases such as keratitis or dry eye disease.

Functional relationship between cationic amino acid transporters and beta-defensins: implications for dry skin diseases and the dry eye

The ocular surface, constantly exposed to environmental pathogens, is particularly vulnerable to infection. Hence an advanced immune defence system is essential to protect the eye from microbial attack. Antimicrobial peptides, such as beta-defensins, are essential components of the innate immune system and are the first line of defence against invaders of the eye. High concentrations of L-arginine and L-lysine are necessary for the expression of beta-defensins. These are supplied by epithelial cells in inflammatory processes. The limiting factor for initiation of beta-defensin production is the transport of L-arginine and L-lysine into the cell. This transport is performed to 80% by only one transporter system in the human, the y(+)-transporter. This group of proteins exclusively transports the cationic amino acids L-arginine, L-lysine and L-ornithine and is also known under the term cationic amino acid transporter proteins (CAT-proteins). Various infections associated with L-arginine deficiency (for example psoriasis, keratoconjuctivitis sicca) are also associated with an increase in beta-defensin production. For the first time, preliminary work has shown the expression of human CATs in ocular surface epithelia and tissues of the lacrimal apparatus indicating their relevance for diseases of the ocular surface. In this review, we summarize current knowledge on the human CATs that appear to be integrated in causal regulation cascades of beta-defensins, thereby offering novel concepts for therapeutic perspectives.

Somatostatin actions via somatostatin receptors on the ocular surface are modulated by inflammatory processes

Recent investigations support the presence of human somatostatin (SS) in the excretory system of the human lacrimal gland. To get deeper insights into a possible role of SS at the ocular surface and in the lacrimal apparatus, we investigated the distribution pattern of SS and its receptors 1-5 (SSTR1-5) by means of RT-PCR, real-time RT-PCR, Western blot and immunodot blot analysis as well as immunohistochemistry in lacrimal gland, tear fluid, conjunctiva, cornea, nasolacrimal duct epithelium, and conjunctival (HCjE) and corneal (HCE) epithelial cell lines. Cell culture experiments with HCjE and HCE were performed to analyze a possible impact of SS and inflammatory mediators on the regulation of SSTR. The results confirmed the presence of SS in lacrimal gland and tear fluid, whereas it was absent at the protein level in all other tissues and cell lines investigated. Expression of SSTR1, -2, and -5 was detectable in lacrimal gland, conjunctiva, cornea, and nasolacrimal ducts. HCjE expressed only hSSTR1 and -2, and HCE revealed only SSTR2. SSTR3 and -4 were not detected in any of the analyzed samples or cell lines. In vitro on cultured immortalized HCjE cells SS leads to a concentration-dependent down-regulation of SSTR1 mRNA but does not affect SSTR2 mRNA expression. Relative expression of SSTR1 and -2 is differentially modulated by proinflammatory cytokines and bacterial components, suggesting that the expression of both receptors is immunomodulated. Our data support an autocrine and paracrine role of SS in the lacrimal system and at the ocular surface and implicate a role of SS in corneal immunology.

Pseudomonas aeruginosa induces interleukin-8 (IL-8) gene expression in human conjunctiva through the recruitment of both RelA and CCAAT/enhancer-binding protein beta to the IL-8 promoter

The purpose of this study was to identify the Pseudomonas aeruginosa-activated signaling pathway leading to interleukin (IL)-8 gene expression and protein synthesis by human conjunctival epithelium. IL-8 protein and mRNA were determined by enzyme-linked immunosorbent assay and reverse transcription-PCR, respectively. Activation of MAPKs and NF-kappaB was analyzed by Western blotting using phosphospecific antibodies. We used transfection with wild-type or mutated IL-8 promoters and cotransfection with transcription factor overexpressing plasmids or small interfering RNAs. Electrophoretic mobility shift assay and chromatin immunoprecipitation (ChIP) were performed for in vitro and in vivo protein-DNA binding studies, respectively. P. aeruginosa increased IL-8 expression at the transcriptional level by phosphorylating CCAAT/enhancer-binding protein beta (C/EBPbeta) via p38MAPK and activating NF-kappaB. The simultaneous involvement of RelA and C/EBPbeta and the integrity of the corresponding consensus sites were required, whereas c-Jun was involved only in basal IL-8 expression. Re-ChIP experiments showed that RelA and C/EBPbeta act together at the IL-8 promoter level upon P. aeruginosa infection. Taken together, our results suggest that P. aeruginosa induces IL-8 promoter expression and protein production in conjunctival epithelial cells by activating RelA and C/EBPbeta and by promoting the cooperative binding of these transcription factors to the IL-8 promoter that in turn activates transcription.

Conjunctival flora in patients with type 1 or type 2 diabetes mellitus

Patients with diabetes mellitus (DM) are prone to infection because glucose in the skin, urine, mucous membranes, and tears promotes growth of microorganisms. Conjunctival flora develops soon after birth, and some saprophytic conjunctival flora play a pathogenic role when immune function is compromised, which can lead to serious infection. DM is one condition that may compromise immune status. In lacrimal function tests of DM patients, a decrease in breakup time (BUT) of lacrimal film and a decrease in Schirmer's test results were seen. In the present study, conjunctival flora in patients with DM was compared with that in controls with regard to type and duration of diabetes and results of lacrimal function tests. Seventeen patients with type 1 DM (n=34 eyes), 66 patients with type 2 DM (n=132 eyes), and 50 control subjects (n=100 eyes) were included. The control group consisted of age-matched patients with no ophthalmologic problems other than refractive error. Glycosylated hemoglobin values were measured with highpressure liquid chromatography with the Hi-AUTOA1c analyzer (Kyoto Daiichi Kagatu Co., Ltd., Kyoto, Japan). Type and duration of diabetes and demographic data were recorded, and routine ophthalmologic examinations were performed; the BUT of lacrimal film was determined, and the results of Schirmer's test were assessed. Microbiologic sampling was performed twice for both eyes with sterile cotton swabs. One sample was incubated in 2 mL of brain-heart infusion broth agar; the other was incubated for the presence of fungi in Sabouraud dextrose agar. Colony morphology, hemolysis, and Gram's stain, as well as catalase, oxidase, and coagulase tests were performed. No growth was observed in 12 of 17 patients (35.4%) with type 1 DM, 28 of 66 patients (21.2%) with type 2 DM, and 25 of 50 control subjects (50%). Staphylococcus epidermidis (11.79%) and Staphylococcus aureus (11.7%) were the most frequently isolated organisms in the type 1 DM group, and S epidermidis (24.2%) and S aureus (21.2%) were the predominant organisms in the type 2 DM group. In control subjects, S epidermidis (22%), S aureus (12%), and Corynebacterium spp (10%) were the most frequently isolated organisms, and the number of eyes with growth of S aureus was significantly higher in the type 2 DM group than in the other groups (P<.01). Patients with diabetes are more prone to postoperative endophthalmitis than are nondiabetics, and preoperative application of antiseptic or antimicrobial agents to the conjunctiva may not sterilize the area. Impaired integrity of the posterior capsule may also increase the risk of endophthalmitis. Postoperative endophthalmitis is usually associated with gram-positive organisms (75%-80%); gram-negative organisms (15%-29%) and fungi (3%-13%) account for a smaller number of cases. A high rate of resistance to penicillin, ampicillin, and tetracycline was observed in S aureus isolates, although resistance to vancomycin was absent, rendering this molecule the most effective therapeutic option. In this study, S epidermidis and S aureus were the 2 most frequently isolated organisms in patients with DM. It is concluded that the conjunctival flora in diabetic subjects differs from that in nondiabetic subjects. This should be considered preoperatively and postoperatively, and prophylactic and postoperative treatment should be administered accordingly to diabetic patients.

The prevalence of adenoviral conjunctivitis at the Wills Eye Hospital Emergency Room

OBJECTIVE

The aim of this study was to evaluate the prevalence of adenoviral conjunctivitis by analyzing data from a prospective clinical study of 50 consecutive patients presenting to the Wills Eye Hospital Emergency Room (WEH ER) with a clinical diagnosis of infectious conjunctivitis from July 2003 to October 2003.

METHODS

The polymerase chain reaction (PCR) was used to evaluate all cases of clinically diagnosed infectious conjunctivitis. Based on the laboratory findings, the prevalence of adenovirus was determined.

RESULTS

Of the 50 consecutive patients with acute infectious conjunctivitis, 31 patients were PCR positive for adenovirus.

CONCLUSIONS

The prevalence of adenoviral conjunctivitis was found by PCR to represent 62% of all patients presenting with a clinical diagnosis of infectious conjunctivitis from July 2003 to October 2003.

[Bacterial conjunctivitis: most prevalent pathogens and their antibiotic sensitivity]

INTRODUCTION

Bacterial conjunctivitis is a self-limiting process, but topical antibiotic treatment is recommended to eradicate the pathogen and reduce symptom duration. Since this treatment is usually empirical and prior cultures are not normally taken, the etiological agents involved in the process are unknown.

PATIENTS AND METHODS

A total of 596 conjunctival exudates from pediatric outpatients with a diagnosis of acute conjunctivitis in Medical Area 6 of Madrid, Spain, were studied over 3 years (from 2000 to 2002 inclusive). The patients were divided into three age groups: group 1 (infants), group 2 (2- to 6-year-olds) and group 3 (7- to 14-year-olds).

RESULTS

A total of 428 bacteria were isolated. The most prevalent bacteria were Haemophilus influenzae (44.8 %) and Streptococcus pneumoniae (30.6 %) followed by Staphylococcus aureus (7.5 %), S. viridans (7.2 %), Moraxella catarrhalis (6.8 %) and Enterobacteriaceae (4.2 %). In 56 exudates (15.1 %), two or more bacteria were isolated and S. pneumoniae 1 H. influenzae were found in 8.1 % of the cases. By age group, S. aureus was significantly more prevalent (p < 0.0001) in group 3 than in groups 1 and 2. Isolation of Enterobacteriaceae, S. viridans and non-fermentative Gram negative bacilli was significantly more frequent (p < 0.05) in group 1 and isolation of S. pneumoniae (p < 0.05) was significantly more frequent in group 2. S. pneumoniae showed the greatest level of resistance to antibiotics used in eye drops and ophthalmic ointments. Ciprofloxacin, chloramphenicol and rifampin were active in the most prevalent pathogens.

CONCLUSIONS

The most prevalent bacteria were H. influenzae and S. pneumoniae. The most active antibiotics in these pathogens were ciprofloxacin, chloramphenicol and rifampin.

Concentrations of levofloxacin, ofloxacin, and ciprofloxacin in human corneal stromal tissue and aqueous humor after topical administration

OBJECTIVE

To evaluate the penetration of commercially available levofloxacin 0.5%, ofloxacin 0.3%, and ciprofloxacin 0.3% topical ophthalmic solutions in human corneal stromal and aqueous humor tissues.

METHODS

A total of 67 patients scheduled to undergo penetrating keratoplasty for treatment of stromal scar or dystrophy, keratoconus, pellucid marginal degeneration, or endothelial disease were enrolled in this prospective, double-blind, 3-center study. To be considered for inclusion, patients had to have an intact corneal epithelium and minimal or no corneal edema (pachymetry < 650 microm). After informed consent was obtained, patients were randomized to receive 1 drop of levofloxacin 0.5%, ofloxacin 0.3%, or ciprofloxacin 0.3% topical ophthalmic solution at approximately 15 and 10 minutes before surgery. Approximately 0.1 mL of aqueous fluid was aspirated by paracentesis through the trephination wound at the onset of surgery, followed by excision of the affected cornea and removal of its epithelium. Specimens were stored frozen at -70 degrees C until assayed by high-performance liquid chromatography.

RESULTS

All 3 fluoroquinolones were well tolerated. A total of 65 corneas and 59 aqueous fluid samples were obtained and assayed. The mean +/- standard deviation corneal concentrations of ciprofloxacin, ofloxacin, and levofloxacin following a 2-drop administration were 9.92 +/- 10.99 microg/g (n = 18), 10.77 +/- 5.90 microg/g (n = 23), and 18.23 +/- 20.51 microg/g (n = 24), respectively. Although corneal stromal levels were highest in the levofloxacin group, the high degree of interpatient variability prevented demonstration of statistically significant differences when compared with ofloxacin (P = 0.377). In contrast, levofloxacin concentrations were approximately twice as high as ciprofloxacin, and this difference reached statistical significance (P = 0.014). The corresponding aqueous humor concentrations of ciprofloxacin, ofloxacin, and levofloxacin were 0.135 +/- 0.231 microg/mL (n = 15), 0.135 +/- 0.111 microg/mL (n = 20), and 0.372 +/- 0.546 microg/mL (n = 24, P < 0.001 versus ciprofloxacin and ofloxacin).

CONCLUSION

The topical administration of all 3 agents was well tolerated in patients undergoing penetrating keratoplasty. Two drops of levofloxacin 0.5% solution results in a 1.7- to 2.7-fold greater penetration into human corneal stromal and aqueous humor tissues than ofloxacin 0.3% or ciprofloxacin 0.3%. The mean intracorneal concentrations of all three agents following 2 drops exceeds the MIC90 for the majority of pathogens causing bacterial keratitis. Topical levofloxacin appears to offer pharmacokinetic and pharmacodynamic advantages over ofloxacin and ciprofloxacin in terms of enhanced transcorneal penetration; however, clinical comparative trials are needed to confirm these relative advantages.

Mycobacterial Infections of the Head and Neck

Mycobacteria are important causes of head and neck infections. Mycobacterial lymphadenitis may be caused by both Mycobacterium tuberculosis and a variety of nontuberculous myocbacteria. Changes in the epidemiology of tuberculosis have caused a shift of the peak age range of tuberculous lymphadenitis from childhood to ages 20 to 40 years. Short-course chemotherapy is highly effective. Mycobacterium avium has become the most common cause of nontuberculous lymphadenitis, but new mycobacterial species are increasingly recognized. Treatment consists primarily of complete surgical excision, although roles for antimycobacterial chemotherapy are being identified. Transient flares of mycobacterial lymphadenitis, which occur during initiation of antituberculous therapy and in HIV-infected patients after initiation of antiretroviral therapy, may respond to short courses of corticosteroids. Tuberculous otitis media has become uncommon. Otitis media due to nontuberculous mycobacterial infection is increasingly seen in patients with pre-existing ear disease and after surgical and otic interventions. Tuberculosis of the eye has also become uncommon but may occur via hematogenous dissemination or direct innoculation. Nontuberculous mycobacteria, most commonly Mycobacterium chelonae and Mycobacterium fortuitum, may cause keratitis, usually after some form of corneal trauma.

Improved detection of microorganisms by polymerase chain reaction in delayed endophthalmitis after cataract surgery

OBJECTIVE

To evaluate whether the use of polymerase chain reaction (PCR) improves the identification of the causative pathogen in eyes developing delayed endophthalmitis after cataract surgery.

DESIGN

Prospective, noncomparative case series.

PARTICIPANTS

Consecutive series of 25 eyes with the clinical diagnosis of delayed endophthalmitis after cataract.

MAIN OUTCOME MEASURE

Presence of bacterial or fungal DNA in aqueous humor and vitreous samples.

RESULTS

In the aqueous humor the causative pathogen was identified in 84% (n = 21) of the eyes by PCR compared with 0% by diagnostic culture and 0% by microscopy. In the vitreous samples the pathogen was identified in 92% (n = 23) of the eyes by PCR compared with 24% by diagnostic culture (n = 6) and 0% by microscopy.

CONCLUSIONS

PCR is useful for the identification of the causative pathogen in delayed endophthalmitis and had a higher rate of positive identification of the causative organism than microscopy or diagnostic culture.

Unusual case of Acanthamoeba polyphaga and Pseudomonas aeruginosa keratitis in a contact lens wearer from Gauteng, South Africa

Acanthamoeba species can cause a chronic, progressive ulcerative keratitis of the eye which is not responsive to the usual antimicrobial therapy and is frequently mistaken for stromal herpes keratitis. An unusual case of coinfection with Acanthamoeba polyphaga and Pseudomonas aeruginosa as causes of corneal keratitis in a contact lens wearer from Gauteng, South Africa, is reported. These two pathogens have previously been assumed to be selectively exclusive. Cysts of the isolated acanthameba tolerated an incubation temperature of 40 degrees C, indicating a pathogenic species. This case highlights the importance of culture methods in the diagnosis of corneal infection and the choice of treatment regimen. The patient's history of careless contact lens-disinfecting habits emphasizes the need to adhere strictly to recommended methods of contact lens care.

Anterior ocular infections: an overview of pathophysiology and treatment

OBJECTIVE

To provide a review of the pathophysiology and treatment of anterior ocular infections.

DATA SOURCE

A MEDLINE search (from 1970 to October 1998) as well as a review of the tertiary literature was performed to identify pertinent literature on pathophysiology and treatment of ocular infections.

STUDY SELECTION AND DATA EXTRACTION

All articles were considered for possible inclusion in the review. Relevant studies were selected for discussion in the article.

DATA SYNTHESIS

Ocular infections are common and vary from self-limiting to sight-threatening. Infections occur in different eye structures; presentation and treatment vary accordingly. Infections can occur when tissues of the eye are exposed to pathogens not normally present, when the eye is damaged, allowing pathogens to overcome the natural defenses of the eye, or in immunosuppressed patients where normal flora may become opportunistic. In deciding on appropriate treatment, both the causative pathogen and the structure(s) affected must be considered. The most likely pathogen can often be determined based on clinical signs and symptoms, patient history, or, in some cases, may need to be determined microbiologically. Differences in drug absorption, penetration, and availability to the various structures of the eye affect treatment decisions. Severity of infection, efficacy and safety of medication, and cost/benefit ratios must be taken into consideration in choosing the proper pharmacologic management of various ocular infections.

CONCLUSIONS

Treatment of ocular infections depends on knowledge of the pathophysiology and drug disposition at the site of infection. An understanding of the current concepts surrounding the management of the anterior ocular infections presented will aid in the provision of optimal patient care.

Actinomyces viscosus postoperative endophthalmitis

Endophthalmitis, attributable to Actinomyces viscosus, developed in a 78-year-old man after cataract surgery. Postoperative endophthalmitis with this organism is a rare occurrence. This report emphasizes the importance of the Actinomyces species as potential eye pathogens and presents antimicrobial susceptibility data for the isolate.

Diagnosis of infectious endophthalmitis after cataract surgery by polymerase chain reaction

PURPOSE

To ascertain whether the use of the polymerase chain reaction (PCR) technique leads to more rapid diagnosis of infectious endophthalmitis after cataract surgery.

SETTING

University Eye Clinic Regensburg, Germany.

METHODS

The aqueous humor and vitreous of 16 eyes with infectious endophthalmitis (10 acute, 6 delayed) were evaluated by microscopy, diagnostic culture, and PCR to detect the infectious agent.

RESULTS

Microscopy of the vitreous was positive in 3 eyes and the culture media results were positive in 7 eyes, all with acute endophthalmitis. Significantly fewer positive results were obtained in the aqueous humor. Using PCR, an infectious agent was detected in the aqueous humor of all 16 eyes and in the vitreous of 14. The vitreous sample was negative in 2 eyes with delayed endophthalmitis.

CONCLUSIONS

Detection of the infectious agent was more successful using PCR than using conventional microbiological tests, especially in the diagnosis of delayed endophthalmitis where the pathogen was detected in the aqueous humor in all eyes.

Virus-induced immunopathology

Several viruses cause damage to the tissue by immunopathological mechanisms. This chapter presents the principal examples of immunopathogenesis caused by the viruses, accompanied by speculations about its management. The most common mechanism of lesion development in virus induced immunopathology involves T cells. Usually, it seems that when CD8+ T cells act as the controlling cell type, lesions are acute and the outcome is decided quickly. The classic example is provided by LCM in mice. The newest candidate may turn out to be SNV infection in humans. Lesions orchestrated primarily by CD4+ T cells can be either acute or long-lasting. Curiously, in the LCMV example, if CD8+ T cells are removed from the scene, immunopathological responses may still occur and these involve CD4+ T cells. Such responses are far more chronic and of lower grade than those mediated by CD8+ T lymphocytes. One possible sequel to chronic inflammatory responses to viruses is that autoreactive inflammatory reactions are initiated and an autoimmune disease occurs. The adage that an ounce of prevention is worth a pound of cure is certainly true in the field of viral pathogenesis. Preventing viral infection or manipulating immune processes during the initial phases of infection is far more successful than attempting to counteract pathological events once underway.