Bacterial blepharitis

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

Etiology. Meibomian gland secretions are responsible for the lipid component of the precorneal tear film. The chemical composition of meibum and/or the lipase action of the normal lid bacteria is thought to contribute to or cause blepharitis and in many cases the dry eye that accompanies it. The composition of meibum has been found to be different in normal and blepharitis patients, and there is a distinct difference between the types of MGD as well. Most studies of lid flora in bacterial blepharitis cases did not find any appreciable isolates from meibum that were not found as normal flora on the lids, therefore disproving the theory that the meibomian glands act as a bacterial reservoir. 

Many practitioners believe that prevention of postoperative infection begins with preoperative management of the cataract patient. Some advocate the use of eyelid scrubs or a topical broad-spectrum antibiotic fiar several days before surgery. This is particularly important with patients who have preexisting conditions, such as conjunctivitis, dacryocystitis, or chronic bacterial blepharitis. Ophthalmic surgeons often administer topical antibiotics within 1 to 2 hours preoperatively to prevent woimd infection. 

Patients with chronic bacterial conjunctivitis often have a concurrent case of blepharitis. Add a lid hygiene regimen to topical antibiotic treatment.12... 

Topical dermatologic preparations of gentamicin are commonly used for the treatment of infected burns. Topical ophthalmic gentamicin (see Table 11-5) is used to treat a variety of bacterial infections of the external eye and adnexa (e.g., conjunctivitis, blepharitis, and keratoconjunctivitis). 

These antibacterial drugs have been used extensively in the past for the treatment of blepharitis and conjimc-tivitis. However, they are rarely used today because of widespread bacterial resistance and the availability of more effective antibacterial drugs. 

Trimethoprim-polymyxin B is effective for the treatment of blepharitis, conjimctivitis, and blepharoconjunctivitis. Side effects are very rare. Because it is clinically effective against H. influenzae and Streptococcus pneumoniae, which are the most common causes of bacterial pediatric eye infections, it is a drug of choice for treating eye infections in children. 

Infectious, bacterial, staphylococcal blepharitis Angular Medial Lateral... 

Infections blepharitis is thought to be caused by a direct infection from bacteria that are either foimd in greater qnantity, are more virulent in nature, or are pathogenic in certain individnals. It has also been postnlated that patients with atopy or other dermatologic conditions (e.g., rosacea) are more likely to have blepharitis and are more prone to staphylococcal infections. Cnrrently S. aureus remains the primary suspect in bacterial and mixed variety blepharitis, although the exact mechanism remains a mystery. 

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. 

In resistant cases of seborrheic blepharitis, bacterial superinfection must be considered and an antibiotic ointment may be added to the regimen if indicated. 

Several forms of blepharitis may cause evaporative dysfunction as well. Increased bacterial colonization of the eyelids causes breakdown of the lipids present on the surfece of the tear film into free fetty acids this in turn causes instability of the lipid layer. 

Everett SL, Kowalski RP, Karenchak LM, et al. An in vitro comparison of the susceptibiUties of bacterial isolates from patients with conjunctivitis and blepharitis to newer and established topical antibiotics. Cornea 1995 14 382-387. 

SPK with a bacterial origin usually is associated with blepharitis, the most common cause of which is infection of the lid margins and glands with Staphylococcus. Additionally, conjunctivitis from organisms such as Streptococcus, Moraxella, and Haemophilus may also cause SPK. 

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. 

Associated ocular and periocular findings also help determine the cause. In blepharitis the Ud margins usually are thickened, red, and scaly lashes may be missing (madarosis). With bacterial conjunctivitis, there is infection of the conjunctiva and a mucopurulent discharge. 

Treatment of SPK is directed toward the underlying cause. Bacterial conjunctivitis should be treated with topical antibiotics (see Chapter 25), and staphylococcal blepharitis should be treated with Ud hygiene and antibiotics (see Chapter 23).Additiotial supportive treatment... 

---