Bacterial Conjunctivitis Medication

Many antibiotic eye preparations can be used as first-line therapy in bacterial conjunctivitis. The justification for treating this condition empirically with a broad-spectrum topical agent is that relatively high levels of the drug are delivered directly to the site of infection. This level of drug concentration exceeds what is normally achieved in body tissues by oral or parenteral routes. Therefore, the antibiotic spectrum of the individual drug is enhanced.

This list of medicines is limited to a few common choices. Many other agents are available. Combination antibiotic-steroid medications are not discussed in this article, as these medicines play a role in postoperative care and are used only with extreme care in the setting of bacterial conjunctivitis.

Class Summary

Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting. Most cases of routine bacterial conjunctivitis respond to the commercially available combination of antibiotics.

Although the aminoglycosides are used in other fields of medicine primarily to treat gram-negative bacteria, the spectrum of efficacy expands to include gram-positive bacteria when used topically for conjunctivitis.

Fluoroquinolones have gained popularity in ocular therapy due to their efficacy in the treatment of bacterial corneal ulcers, although many bacterial-resistant strains are emerging. Fluoroquinolones have been used mostly as second-line agents in routine bacterial conjunctivitis.

Neonatal chlamydial infection is treated with oral erythromycin. Doxycycline is used to treat the mother of a neonate with chlamydial infection as well as her at-risk contacts.

Intravenous penicillin G is used for neonatal gonorrhea infections. Third-generation cephalosporins are used in the treatment of adult gonorrhea infections.

Gentamicin (Garamycin, Gentak)

Gentamicin is an aminoglycoside antibiotic used for gram-negative bacterial coverage. Most cases of bacterial conjunctivitis will respond to this agent, including those caused by pseudomonads, Staphylococcus aureus, group A streptococci, S pneumoniae, and H influenzae. Gentamicin is commercially available in solution or ointment form.

Erythromycin topical (Ilotycin)

Topical erythromycin is indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections. It is effective in most cases of bacterial conjunctivitis, including those caused by S aureus, group A streptococci, S pneumoniae, and H influenzae.

Azithromycin ophthalmic (AzaSite)

This ophthalmic macrolide antibiotic is indicated for bacterial conjunctivitis caused by CDC coryneform group G bacteria, H influenzae, S aureus, Streptococcus mitis group, and S pneumoniae.

Bacitracin ophthalmic

Bacitracin prevents transfer of mucopeptides into growing cell wall, inhibiting bacterial growth. Most cases of routine bacterial conjunctivitis will respond to bacitracin, including those caused by group A streptococci, S aureus, S pneumoniae, and H influenzae.

Ciprofloxacin ophthalmic (Ciloxan)

Ciprofloxacin inhibits bacterial growth by inhibiting DNA gyrase. It is indicated for superficial ocular infections of the conjunctiva or cornea caused by strains of microorganisms susceptible to this agent. It is effective in most cases of routine conjunctivitis, including those caused by S aureus, group A streptococci, H influenzae, and Pseudomonas aeruginosa. It may not cover all cases of S pneumoniae. Newer classes of fluoroquinolones (eg, gatifloxacin, moxifloxacin) are available and are sometimes used for conjunctivitis or a red eye, particularly in the perioperative period for eye surgery.

Trimethoprim and polymyxin B (Polytrim)

This combination is used for ocular infections, involving cornea or conjunctiva, resulting from strains of microorganisms susceptible to this antibiotic. It is available as a solution and ointment. This combination of drugs is effective against the common causes of bacterial conjunctivitis, including group A streptococci, S aureus, H influenzae, S pneumoniae, and pseudomonads.

Erythromycin (E.E.S., Ery-Tab, Erythrocin)

Erythromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes causing RNA-dependent protein synthesis to arrest. It is effective in the treatment of chlamydial infections.

Doxycycline (Doryx, Vibramycin, Doryx)

Doxycycline inhibits protein synthesis and thus bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. Doxycycline is a tetracycline antibiotic that is effective in the treatment of adult chlamydial infections.

Penicillin G (Pfizerpen)

Penicillin interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms. It is used in the hospital setting for neonatal gonorrheal infections.

Ceftriaxone (Rocephin)

A third-generation cephalosporin that is an adjunct in the treatment of adult gonorrhea infections, ceftriaxone arrests bacterial growth by binding to one or more penicillin-binding proteins.

Tobramycin ophthalmic (Tobrex, AK-Tob)

This agent interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits, which results in a defective bacterial cell membrane. It is available as a solution, ointment, and lotion.

Neomycin

Neomycin is used in the treatment of minor infections. It inhibits bacterial protein synthesis and growth.

Ofloxacin ophthalmic (Ocuflox)

A pyridine carboxylic acid derivative with broad-spectrum bactericidal effect, ofloxacin inhibits bacterial growth by inhibiting DNA gyrase. It is indicated for superficial ocular infections of the conjunctiva or cornea caused by susceptible strains of microorganisms.

Levofloxacin ophthalmic (Quixin, Iquix)

Levofloxacin is an S (-) enantiomer of ofloxacin. It inhibits DNA gyrase in susceptible organisms, thereby inhibiting relaxation of supercoiled DNA and promoting breakage of DNA strands.

Gatifloxacin ophthalmic solution 0.3% (Zymaxid)

A fourth-generation fluoroquinolone ophthalmic indicated for bacterial conjunctivitis, gatifloxacin 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.

Gatifloxacin is indicated for bacterial conjunctivitis due to Corynebacterium propinquum, S aureus, Staphylococcus epidermidis, Streptococcus mitis, S pneumoniae, or H influenzae.

Besifloxacin ophthalmic (Besivance)

Besifloxacin is a quinolone antimicrobial ophthalmic suspension indicated for bacterial conjunctivitis. Susceptible bacteria include CDC coryneform group G (Corynebacterium pseudodiphtheriticum, Corynebacterium stratum), H influenza, Moraxella lacunata, S aureus, S epidermidis, Staphylococcus hominis, Staphylococcus lugdunensis, S mitis, Streptococcus oralis, S pneumoniae, and Streptococcus salivarius. This agent is available as a 0.6% ophthalmic suspension.