Ophthalmologic Manifestations of Escherichia Coli 

Updated: Feb 05, 2016
Author: Donny W Suh, MD, FAAP; Chief Editor: Hampton Roy, Sr, MD 

Overview

Background

The genus Escherichia is named after Theodor Escherich who isolated the type species of the genus in 1885. Escherichia coli is a gram-negative rod that is found as a normal commensal in the GI tract, which can produce ocular infection including corneal ulcer and endophthalmitis, which can result in a devastating outcome. Early recognition and appropriate treatment is crucial. These infections most commonly occur in patients who are debilitated, immunocompromised, or diabetic or in corneas with an underlying pathologic condition.

Pathophysiology

E coli is rarely found in the normal flora of the conjunctiva. It is most commonly seen as a source of infection in ophthalmia neonatorum. Low birth weight and low gestational age in infants with clinical signs of conjunctivitis should raise the suspicion for a gram-negative cause.[1] E coli endophthalmitis is a rare complication of E coli septicemia. Antimicrobial resistance occurs through plasmid-mediated determinants. These multiresistant plasmids can be transferred by conjugation. It has a poor prognosis, and early diagnosis and treatment are essential to retain useful vision.

These infections most commonly occur in patients who are debilitated, immunocompromised, or diabetic or in corneas with an underlying pathologic condition. Exogenous endophthalmitis is usually associated with trauma or intraocular surgery. In endogenous endophthalmitis, urinary tract infection was the most common primary site of infection and nearly all patients are diabetic.

Early recognition and appropriate treatment is crucial because E coli endophthalmitis has an extremely poor prognosis. Depending on the severity, most patients need aggressive management and early medical and surgical intervention.

Epidemiology

Frequency

United States

Approximately 5-10% of endogenous bacterial endophthalmitis is due to E coli. Exogenous endophthalmitis associated with intraocular surgery is 0.1-0.5%. Of these infections, E coli is rare a cause.

Endophthalmitis occurs following 2-7% of penetrating injuries. Incidence is higher in association with intraocular foreign body. Of these infections, E coli is a rare cause.

International

International frequency is unknown.

Mortality/Morbidity

In endophthalmitis, the course of illness is very rapid, and complete destruction of intraocular tissues occurs. Corneal infection due to E coli produce indolent corneal ulcers with poor prognosis because most of these patients of have an underlying immunocompromised disorder or have abnormal corneal surface with compromised protective barrier.

Sex

Men are 4 times more likely to have ocular trauma than women, which may lead to bacterial endophthalmitis. For corneal ulcer due to E coli, no difference is noted in frequency between the sexes.

Age

E coli may be seen as a source of infection in ophthalmia neonatorum in neonates. Also, endophthalmitis may occur in neonates following meningitis. However, almost all cases of E coli endophthalmitis have been in adults with an immunocompromised state or with diabetes.

 

Presentation

History

Past ocular history should be assessed, as follows:

  • Previous eye injury

  • Infection

  • Surgery

  • Diabetic eye disease

Past medical history should be assessed, as follows:

  • Diabetes

  • Immunocompromised host

  • Intravenous drug abuser

  • Urinary tract infection

Visual complaints should be assessed, as follows:

  • Decreased vision

  • Eyelid edema

  • Diplopia red eye

  • Mild-to-severe ocular pain

  • Photophobia

  • Discharge

Physical

Signs are as follows:

  • Focal white opacity in the corneal stroma

  • Epithelial defect that stains fluorescent

  • Stroll edema and inflammation surrounding the infiltrate

  • Conjunctival injection

  • Corneal thinning

  • Anterior chamber reaction

  • Hypopyon (as is shown in the image below)

    Bacterial corneal ulcer with hypopyon. Bacterial corneal ulcer with hypopyon.
  • Mucopurulent discharge

  • Upper eyelid edema

  • Posterior synechiae

  • Hyphema

  • Glaucoma

Causes

Exogenous causes are as follows:

  • Immunocompromised state

  • Irregular corneal epithelium

  • Trauma

  • Ocular surgery

Endogenous causes are as follows:

  • Urinary tract infection

  • Endocarditis

  • Meningitis

  • Systemic infection

 

DDx

Diagnostic Considerations

With anterior segment involvement, consider the following:

  • Bacterial corneal ulcer

  • Fungal corneal ulcer (eg, following trauma)

  • Acanthamoeba corneal ulcer

  • Viral corneal ulcer (eg, herpes simplex, herpes zoster)

  • Atypical mycobacteria corneal ulcer

  • Sterile ulcer (collagen vascular disease)

  • Staphylococcal hypersensitivity

With posterior segment involvement, consider the following:

  • Retinochoroidal fungal endophthalmitis

  • Retinochoroidal infection (eg, toxoplasmosis, toxocariasis)

  • Noninfectious posterior uveitis (eg, sarcoidosis, pars planitis)

  • Neoplastic conditions

Differential Diagnoses

 

Workup

Laboratory Studies

The following studies are indicated in patients with suspected E coli infection:

  • CBC count with cell differentials

  • Blood agar

  • Sabouraud dextrose agar without cycloheximide

  • Thioglycolate broth

  • Chocolate agar

  • Löwenstein-Jensen medium

  • Nonnutrient agar with E coli overlay

  • Slides - Gram stain, Giemsa stain

Imaging Studies

CT scanning of the orbit and head may be helpful in case of trauma to look for a foreign body.

Procedures

With a corneal ulcer, anesthetize the cornea with topical drops, and, at the slit lamp, scrape the base and the leading edge of the infiltrate with the Kimura spatula, and place on the culture medium or slide.

With endophthalmitis, diagnostic and therapeutic vitrectomy is used to confirm the diagnosis and to evaluate the organisms' sensitivity to antibacterial agents.

Histologic Findings

E coli is a gram-negative rod. E coli has a fermentative and respiratory type of metabolism.

 

Treatment

Medical Care

Ocular treatment

Cycloplegic treatment is with scopolamine 0.25%.

Antibiotic treatment is as follows:

  • E coli conjunctivitis: Topical ciprofloxacin, ofloxacin, gatifloxacin, levofloxacin, moxifloxacin, or 0.3% tobramycin ophthalmic solutions are applied approximately 6-8 times daily until the infection appears to be resolved.

  • Smaller and peripheral corneal infiltrate: Intensive topical therapy infiltrate/ulcers; topical ciprofloxacin, ofloxacin, gatifloxacin, levofloxacin, moxifloxacin, or 0.3% tobramycin ophthalmic solutions are applied every hour while awake until the infection appears to be resolved. Reassess on a daily basis.

  • Large and central infiltrate: Fortified tobramycin, gentamicin (15 mg/mL), or fluoroquinolone (eg, ciprofloxacin, gatifloxacin, levofloxacin, moxifloxacin) 1 drop every 5 minutes for 5-7 doses, then repeat every other hour for 24 hours alternating with fortified cefazolin (50 mg/mL) or vancomycin (25 mg/mL) 1 drop every 5 minutes for 5-7 doses, then repeat every other hour for 24 hours; patient needs daily evaluation.[2] Consider subconjunctival antibiotics of gentamicin or tobramycin (20-40 mg).

  • Endophthalmitis: Intravitreal injection of gentamicin or tobramycin 100-300 µg can be used. Amikacin can also be used at 400 µg. Intravitreal injection consists of total 0.1 mL. Intravitreal steroids are controversial. For eyes with corneal thinning, place a corneal shield without a patch. Contact lenses should not be worn. Oral pain and nausea medication may be given. Oral fluoroquinolone (ciprofloxacin 500 mg PO bid) should be considered because it penetrates the posterior segment well. Topical steroids in combination with antibiotics may reduce the massive inflammatory response of the eye, which is often as destructive as the infection.

Systemic treatment

The choice of an appropriate antimicrobial agent in E coli infections depends on the site, type, and severity of infection. A number of antibiotics are effective against E coli, but no particular drug is uniformly active against all strains of E coli; therefore, sensitivity testing should guide the choice of antibiotics. Antimicrobial resistance occurs through plasmid-mediated determinants, several of which can be found in the same plasmid. These multiresistant plasmids can be transferred by conjugation.

For less severe E coli infections, the initial treatment of choice may be ampicillin (2-4 g/d intravenous [IV] or intramuscular [IM]). Other penicillins with β -lactamase inhibitor, cephalosporins, nitrofurantoin, and trimethoprim/sulfamethoxazole may also be considered.

For more severe infections, ampicillin/sulbactam could be given (3 g IV q6h). Imipenem/cilastatin, ciprofloxacin IV, or cefotaxime may also be considered.

Kanamycin is generally indicated for the initial treatment of serious E coli infections. Severe urinary tract infections that seem to be resistant to other antimicrobial agents have responded to daily doses of kanamycin (15 mg/kg IM in divided doses q6-8h).

Alternative treatment may be a total daily dose of parenteral gentamicin (3-5 mg/kg in divided doses q8h). In severe infections that appear to be resistant to kanamycin and gentamicin, amikacin is indicated. Amikacin is given daily (15 mg/kg in 2-3 equally divided doses).

In severe cases of sepsis, a combination of antibiotics is given, which includes ampicillin and an aminoglycoside; the choice of which is based on knowledge of local susceptibility patterns. Ampicillin/sulbactam or cefotaxime (a potent third-generation cephalosporin) is a suitable alternative, especially if an aminoglycoside-resistant nosocomial organism is suspected.

Neomycin appears to be most effective against E coli gastroenteritis. An oral daily dose of 25 mg/kg is usually indicated for 1-2 days.

Surgical Care

Penetrating corneal transplant may be needed for corneal perforation.

Posterior vitrectomy may be needed to reduce the infective load and provide sufficient material for diagnostic culture and pathology.

Consultations

Consultations with anterior segment surgeons and/or a retinal specialist may be warranted.

Diet

Diet is normal, but if surgery is indicated, convert to nothing by mouth (NPO).

Activity

Bed rest should be initiated. Admit to the hospital for monitoring if necessary under the following conditions:

  • Sight-threatening infection

  • Patient not able to administer medication

  • Risk of noncompliance

  • Patient not able to return daily

 

Medication

Medication Summary

The goals of pharmacotherapy are to eradicate the E coli infection, to reduce morbidity, and to prevent complications.

Antibiotics (fluoroquinolone)

Class Summary

Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.

Ciprofloxacin ophthalmic (Ciloxan)

Inhibits bacterial growth by inhibiting DNA gyrase. Indicated for superficial ocular infections of the conjunctiva or cornea caused by strains of microorganisms susceptible to ciprofloxacin.

Ofloxacin ophthalmic (Ocuflox)

Pyridine carboxylic acid derivative with broad-spectrum bactericidal effect. Inhibits bacterial growth by inhibiting DNA gyrase. Indicated for superficial ocular infections of the conjunctiva or cornea caused by strains of microorganisms susceptible to ofloxacin.

Tobramycin ophthalmic (Tobrex, AKTob)

Interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits, which results in a defective bacterial cell membrane. Available as a solution, ointment, and lotion.

Gentamicin ophthalmic (Ocumycin, Genoptic)

Aminoglycoside antibiotic used for gram-negative bacterial coverage.

Cefazolin (Kefzol, Zolicef)

First-generation cephalosporin antibiotic for gram-positive bacterial coverage. Commonly used in combination with an aminoglycoside to achieve broad spectrum. This 50-133 mg/mL solution must be compounded.

Vancomycin (Lyphocin, Vancoled, Vancocin)

Potent antibiotic directed against gram-positive organisms and active against Enterococcus species. Useful in the treatment of septicemia and skin structure infections. Indicated for patients who cannot receive, or have failed to respond to penicillins and cephalosporins or have infections with resistant staphylococci. For abdominal penetrating injuries, it is combined with an agent active against enteric flora and/or anaerobes.

To avoid toxicity, current recommendation is to assay vancomycin trough levels after third dose drawn 0.5 h prior to next dosing. Use creatinine clearance to adjust dose in patients diagnosed with renal impairment.

Used in conjunction with gentamicin for prophylaxis in patients with penicillin allergy undergoing GI or genitourinary procedures.

Gatifloxacin ophthalmic (Zymar)

Fourth-generation fluoroquinolone ophthalmic indicated for bacterial conjunctivitis. Elicits a dual mechanism of action by possessing an 8-methoxy group, thereby inhibiting the enzymes DNA gyrase and topoisomerase IV. DNA gyrase is involved in bacterial DNA replication, transcription, and repair. Topoisomerase IV is essential in chromosomal DNA partitioning during bacterial cell division.

Levofloxacin ophthalmic (Quixin)

S-enantiomer of ofloxacin. Inhibits DNA gyrase in susceptible organisms, thereby inhibiting relaxation of supercoiled DNA and promoting breakage of DNA strands.

Moxifloxacin ophthalmic (Vigamox)

Indicated to treat bacterial conjunctivitis. Elicits antimicrobial effects. Inhibits topoisomerase II (DNA gyrase) and IV enzymes. DNA gyrase is essential in bacterial DNA replication, transcription, and repair. Topoisomerase IV plays a key role in chromosomal DNA portioning during bacterial cell division.

Cycloplegics

Class Summary

Instillation of a long-acting cycloplegic agent can relax any ciliary muscle spasm that can cause a deep aching pain and photophobia.

Scopolamine ophthalmic (Isopto, Isopto Hyoscine Ophthalmic)

Blocks the action of acetylcholine at parasympathetic sites in the smooth muscle, producing pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).

Corticosteroids

Class Summary

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

Prednisolone ophthalmic (Pred Forte)

Treats acute inflammations following eye surgery or other types of insults to eye. Decreases inflammation and corneal neovascularization. Suppresses migration of polymorphonuclear leukocytes and reverses increased capillary permeability. In cases of bacterial infections, concomitant use of anti-infective agents is mandatory; if signs and symptoms do not improve after 2 days, reevaluate patient. Dosing may be reduced, but advise patients not to discontinue therapy prematurely.

 

Follow-up

Further Outpatient Care

In patients with E coli, daily evaluation is initially indicated, including the following:

  • Repeated measurement of visual acuity, the size of the infiltrate, ulcer, and epithelial defect

  • Anterior chamber reaction

  • Intraocular pressure

  • Level of hypopyon

  • Fundus examination

In an impending or completed corneal perforation, consider a corneal transplant or patch graft.

Cyanoacrylate tissue glue may also work in a treated corneal ulcer.

Inpatient & Outpatient Medications

The following may be needed:

  • Topical antibiotics

  • Cycloplegics

  • Topical steroids

  • Periocular antibiotics

  • Oral/intravenous antibiotics if needed

  • Antiemetics

  • Analgesics

Deterrence/Prevention

Early detection and aggressive treatment are important.

Complications

Complications may include the following:

  • Cataract formation

  • Corneal perforation

  • Glaucoma

  • Hyphema

  • Loss of vision

  • Retinal detachment

  • Possible need for enucleation

  • Meningitis

Prognosis

Because of the aggressive nature of the disease, prognosis is poor unless aggressive and early treatment is initiated.