Keratitis bacterial

Bacterial keratitis Bacterial keratitis associated with the use of multiple-dose containers of topical ophthalmic products has been reported. Serious damage to the eye and subsequent loss of vision may result from using contaminated preparations. Benzalkonium chloride Benzalkonium chloride is a preservative used in some of these products that may be absorbed by soft contact lenses. Patients wearing soft... 

Untreated bacterial keratitis is associated with corneal scarring and potential loss of vision. Corneal perforation may cause the loss of the eye. 

The rate of progression of signs and symptoms varies depending on the infecting organism. A differential diagnosis for keratitis must include viral, fungal, and nematodal infections in addition to bacterial causes.19... 

Thirty thousand cases of microbial keratitis occur annually in the United States.18 Microbial keratitis encompasses bacterial, fungal, and Acanthamoeba keratitis.19 Only bacterial keratitis, the most common form, is discussed here. 

Bacterial keratitis is a broad term for a bacterial infection of the cornea. This includes corneal ulcers and corneal abscesses. The cornea in a healthy eye has natural resistance to infection, making bacterial keratitis rare. However, many factors predispose a patient to bacterial infection by compromising the defense mechanisms of the eye (Table 60-5).19... 

The most common pathogens in bacterial keratitis are Pseudomonas (including Pseudomonas aeruginosa) and other gram-negative rods, staphylococci, and streptococci. If the keratitis is related to the use of contacts, Pseudomonas is the most common cause followed by Serratia marcescens. For hospitalized infants and adults on respirators, Pseudomonas is the most common.19... 

Untreated bacterial keratitis is associated with corneal scarring and potential loss of vision. Corneal perforation may occur and the patient may lose the eye. In virulent organisms, this destruction may occur within 24 hours. Central corneal scarring may result in vision loss even after successful eradication of the organism. 

All cases of suspected bacterial keratitis require prompt ophthalmology consultation to prevent permanent vision loss.10... 

Topical corticosteroids are employed in some cases of bacterial keratitis. The suppression of inflammation may reduce corneal scarring. However, local immunosuppression, increased ocular pressure, and reappearance of the infection are disadvantages to their use. There is no conclusive evidence that they alter clinical outcomes. If the patient is already on topical corticosteroids when the keratitis occurs, discontinue use until the infection is eliminated.19... 

Efficacy In other conditions The clinical efficacy in the treatment of stromal keratitis and uveitis caused by herpes simplex or ophthalmic infections caused by vaccinia virus and adenovirus, or in the prophylaxis of herpes simplex virus keratoconjunctivitis and epithelial keratitis has not been established by well-controlled clinical trials. Not effective against bacterial, fungal, or chlamydial infections of the cornea or trophic lesions. 

I Unlabeled Uses Treatment of bacterial blepharitis, blepharoconjunctivitis, bacterial keratitis, keratoconjunctivitis... 

Bacterial keratitis is one of the most frequent ophthalmic infections. In a meta-analysis of publications from 1950 to 2000, the use of a topical glucocorticoid before the diagnosis of bacterial keratitis significantly predisposed to ulcerative keratitis in eyes with preexisting corneal disease (OR = 2.63 95% Cl = 1.41, 4.91). Previous glucocorticoid use significantly increased the risk of antibiotic failure or other infectious complications (OR = 3.75 95% Cl = 2.52, 5.58). The use of glucocorticoids with an antibiotic for the treatment of bacterial keratitis did not increase the risk of complications, but neither did it improve the outcome of treatment. 

Ghelardi, E., et al. 2004. A mucoadhesive polymer extracted from tamarind seed improves the intraocular penetration and efficacy of rufloxacin in topical treatment of experimental bacterial keratitis. Antimicrob Agents Chemother 48 3396. 

Ghelardi, E., Tavanti, A., Davini, P., Celandroni, F., Salvetti, S., Parisio, E., Boldrini, E., Senesi, S. and Campa, M. (2004) A mucoadhesive polymer extracted from tamarind seed improves the intraocular penetration and efficacy of rufloxacin in topical treatment of experimental bacterial keratitis. Antimicrobial Agents and Chemotherapy 48(9), 3396-3401. 

Kowalski RP, et al. Gatifloxacin and moxifloxacin an in vitro susceptibility comparison to levofloxacin, ciprofloxacin, and ofloxacin using bacterial keratitis isolates. Am. J. Ophthalmol., 2003, 136, 500-505. 

All the available ophthalmic fluoroquinolones are indicated for bacterial conjunctivitis with a treatment regimen of usually one to two drops four times a day. However, because the newer gatifloxacin and moxifloxacin have wider spectra and less resistance, they should probably be reserved for treatment of the more serious infection, bacterial keratitis. 

Ciprofloxacin and ofloxacin are also indicated for bacterial keratitis caused by a variety of pathogens. These... 

Although the fourth-generation drugs, moxifloxacin and gatifloxacin, are not approved for treatment of bacterial keratitis, they are now the preferred fluoroquinolones for this disease. They have wide spectra of activity and lesser resistance by the common corneal pathogens, especially the gram-positive cocci. 

Acanthamoeba keratitis is known to be difficult to diagnosis and to treat. Most patients are initially treated fiar viral, fungal, of bacterial keratitis before the diagnosis of Acanthamoeba. Most Acanthamoeba infections are associated with contact lens wear (85% to 92%), but a smaller number are secondary to trauma. The incidence of Acanthamoeba keratitis may be greater than 1 per 30,000 contact lens wearers per year as indicated by cohort studies and questionnaires. The frequency oi Acanthamoeba keratitis in contact lens wearer may be 1 per 10,000/year or higher. 

American Academy of Ophthalmology. Preferred practice pattern. Bacterial keratitis. Retrieved 2006 from http // www.AAO.org... 

Leibowitz HM. Clinical evaluation of ciprofloxacin 0.3% ophthalmic solution for treatment of bacterial keratitis. Am J Ophthalmol 1991 112(suppl) S34-S47. 

Parmar R Salman A, Kalavathy CM, et al. Comparison of topical gatifloxacin 0.3% and ciprofloxacin 0.3% for the treatment of bacterial keratitis. AmJ Ophthalmol 2006 141 282-286. 

Leibowitz HM, Kupferman A. Topically administered corticosteroids. Effects on antibiotic-related bacterial keratitis. Arch Ophthalmol 1986 98 1287-1290. 

For many years S. aureus exotoxins have been considered the cause of associated conditions snch as blepharo-keratoconjunctivitis. It has been determined that all Staphylococcus species produce exotoxins, and becanse these species are foimd on the Uds of both normal and blepharitis patients, they are most likely not primarily responsible for the findings. More recent evidence suggests that an abnormal blink mechanism or destabilization of the tear film due to bacterial Upolytic enzyme pathways and increased hydrolysis of phosphoUpids may be the canse. It has also been shown that a delayed hypersensitivity to these toxins can prodnce the marginal keratitis seen in many patients. 

The use of Mini-tip Culturette (Becton Dickinson, Cockeysville, MD) has been compared with traditional culture techniques using a rabbit model as well as commimity-acquired presumed bacterial keratitis. The sensitivity of the Mini-tip Culturette was 83-3% and the specificity 100%. Detected organisms included group A P-hemolytic Streptococcus, S. aureus, coagulase-negative Staphylococcus, Serratia marcescens, and Pseudomonas aeruginosa. 

Goldstein MH, Kowalski RP, Gordon Yf. Emerging fluoroquinolone resistance in bacterial keratitis a 5-year review. Ophthalmology 1999 106 1313-1318. 

Limberg MB. A review of bacterial keratitis and bacterial conjunctivitis. Am J Ophthalmol 1991 112 2S-9S. 

During the examination, and when considering the history of the traumatic episode, it is important to rule out corneal laceration or penetration, retained foreign bodies, or other ocular traumatic sequelae. Clean corneal abrasions should not exhibit opaque infiltration suggestive of bacterial or fungal keratitis. 

Because most corneal abrasions involve loss of only the superficial epithelial cells, the lesions generally heal in 24 to 72 hours without scar formation. As the cornea is monitored during follow-up care, it is important to determine that the signs and symptoms are consistent with the healing of a clean abrasion and that bacterial or fungal keratitis does not develop, particularly in abrasions caused by vegetative matter. Once the acute care aspects associated with the abrasion are resolved, it is helpful to discuss with the patient the appropriateness of protective eyewear, particularly if the patient is monocular. Protective eyewear may be needed in occupational, domestic, or recreational settings. 

A follow-up examination is perfttrmed 24 hours later. During follow-up examinations it is important to monitor for signs of secondary bacterial keratitis, secondary fungal keratitis, or an intraocular foreign body that may have... 

Examination typically reveals diffuse SPK erosions and also may disclose punctate epithelial keratopathy that is visible as small grayish opacities in the epithelium. The location and pattern of this keratitis can be helpful in determining the etiology (Box 26-1) and in distinguishing the condition from bacterial-related causes. SPK from blepharitis usually is more severe in the inferior one-third of the cornea where it contacts the staphylococcal exotoxins from infection of the lower lid. In cases of SPK caused by bacterial conjunctivitis, the entire cornea may be involved. 

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