Pseudomonas aeruginosa keratitis

Introduction to Pseudomonas aeruginosa keratitis Pseudomonas keratitis (pseudomonaskeratitis) is an extremely severe acute suppurative corneal ulcer characterized by a ring-shaped abscess caused by typical Gram-negative bacilli, often sweeping the entire cornea in a very short time and causing devastating The destruction is extremely serious. Once it happens, it must be rescued immediately. basic knowledge The proportion of illness: 0.002% Susceptible people: no specific population Mode of infection: non-infectious Complications: corneal staphyloma

Causes of Pseudomonas aeruginosa keratitis

Bacterial infection (35%):

Pseudomonas aeruginosa is highly pathogenic. The main pathogenic substances are endotoxin (cell wall lipopolysaccharide) and exotoxin (elastic protease, alkaline protease and exotoxin A). Experiments have shown that after animal experiments, Proliferate rapidly in the cornea, releasing toxins and enzymes, and at the same time causing infiltration of neutrophils, leading to corneal tissue melting and necrosis.

Disease factors (25%):

Corneal trauma caused by corneal foreign body removal or various causes (such as keratitis, corneal softening, corneal chemical burns and thermal burns, exposed keratitis, etc.).

Environmental factors (15%):

Wear contact lenses for too long or use a cleaning solution or disinfectant contaminated with Pseudomonas aeruginosa.

Other factors (10%):

Use contaminated eye drops and surgical instruments.

Pseudomonas aeruginosa keratitis prevention

Moderate contact lens; eye drops and ophthalmic surgical instruments should be thoroughly disinfected to prevent iatrogenic infection; pay attention to prevent corneal trauma.

Complications of Pseudomonas aeruginosa keratitis Complications, corneal staphyloma

Endophthalmitis, adhesive corneal leukoplakia or corneal staphyloma, the lesion surface and conjunctival sac have yellow-green purulent secretions, and have a special odor. The anterior chamber may have yellowish white empyema, sometimes filled with the anterior chamber. Because the annular abscess area isolates the cornea from the corneal surrounding blood vessels, blocks the nutrient supply, and the Pseudomonas aeruginosa and inflammatory reaction cause the epithelial cells to release collagenase, the ulcer rapidly expands and deepens, and the whole cornea can be affected in about 1 day. The formation of a full corneal abscess, even affecting the sclera can lead to blindness.

Pseudomonas aeruginosa keratitis symptoms common symptoms keratitis eye conjunctival edema and corneal ulcer conjunctival hyperemia corneal foreign body abscess severe pain tears edema purulent secretions

1. Symptoms: acute onset, rapid development of the disease, short incubation period (6 ~ 24h), patients feel severe pain in the eyes, shame and tears, sharp decline in vision, examination of visible eyelid swelling, conjunctival mixed congestion, edema.

2. Signs: At the beginning of the lesion, grayish white infiltration occurs at the corneal trauma, and rapidly expands outward to form a ring-shaped or semi-annular gray-yellow infiltration (abscess). The lesion surface and conjunctival sac have yellow-green purulent secretions, and have special Odor, yellowish white empyema in the anterior chamber, sometimes filled with anterior chamber, because the annular abscess area isolates the cornea from the corneal surrounding blood vessels, blocks nutrient supply, plus Pseudomonas aeruginosa and inflammatory reaction causes epithelial cells to release collagen Enzymes, ulcers rapidly expand and deepen, can spread to the whole cornea in about 1 day, forming a full corneal abscess, and even affect the sclera.

Examination of Pseudomonas aeruginosa keratitis

Scraping the secretions or necrotic tissue of the corneal ulcer area for smear and Gram staining, we can find a relatively small Gram-negative bacillus, Pseudomonas aeruginosa grows rapidly on agar medium, and colonies can appear 24 hours later. Generally, the colonies are large, round, the edges are slightly uneven, and the appearance is sticky. In order to find the cause, the eye drops and surgical instruments applied to the patients can be cultured.

When the corneal infiltration is severe and the intraocular condition cannot be observed, it is feasible to confirm the intrabulbar lesion by B-ultrasound.

Diagnosis and diagnosis of Pseudomonas aeruginosa keratitis

diagnosis

According to the medical history, the characteristics of acute onset (the rapid formation of corneal ulcers, with yellow-green mucopurulent secretions, anterior chamber reaction, etc.), can be used for preliminary clinical diagnosis, and the diagnosis must rely on microbiology laboratory tests.

1. There is a history of corneal trauma (including wearing contact lenses) or corneal foreign body removal before onset.

2. The onset is in a hurry and the ulcers are on the rise.

3. Typical annular infiltration and ulcer morphology and anterior chamber empyema.

4. A large amount of yellow-green sticky secretions.

Differential diagnosis

Pseudomonas aeruginosa corneal ulcers should be differentiated from Staphylococcus aureus, pneumococcal and Moraxella keratitis, and the final identification still depends on pathogen examination.

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