Bacterial Conjunctivitis (Pink Eye) Medication

Updated: Feb 07, 2023
  • Author: Karen K Yeung, OD, FAAO; Chief Editor: Andrew A Dahl, MD, FACS  more...
  • Print

Medication Summary

Most bacterial conjunctivitides are self-limiting, [12] although topical antibiotics are recommended [29] because they can shorten the duration of the disease [30] and prevent the spread of infection. Broad-spectrum antibiotics are generally used empirically as first-line therapy for bacterial conjunctivitis. Topical as opposed to oral antibiotics are recommended to deliver high levels of the drug directly to the site of infection, exceeding what is normally achieved in body tissues by oral or parenteral routes. Therefore, the antibiotic action of the individual drug is enhanced.

For severe conjunctivitis marked by copious purulent discharge and eye inflammation, cultures are needed to guide the choice of antibiotic. Fortified antibiotics such as combination aminoglycosides and cephalosporins have a similar efficacy profile to fluoroquinolones. However, resistance to early-generation fluoroquinolones, moxifloxacin, and levofloxacin has been increasing, while some resistance profiles, particularly in multidrug-resistant staphylococci, appear to be more favorable for besifloxacin. [31, 32] Oral antibiotics are recommended for gonococcal and chlamydial infections.



Class Summary

Most cases of routine bacterial conjunctivitis respond to the commercially available combination of antibiotics, artificial tears, lid scrubs, oral analgesics, and, often, a topical antihistamine to relieve itching and discomfort.

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. Aminoglycosides are not used orally and hence have lower rates of systemic bacterial resistance. They are especially effective against gram-negative organisms. These are also useful in mild bacterial conjunctivitis. Polymyxin B with trimethoprim is also efficacious for mild conjunctivitis, especially in pediatric patients, but it may blur visions because it is in an ointment form. Both aminoglycosides and polymyxin B/trimethoprim are significantly more effective against methicillin-resistant staphylococci than most fluoroquinolones or sulfonamides.

Fluoroquinolones inhibit bacterial DNA gyrase and topoisomerase IV. They offer broad-spectrum coverage for bacterial conjunctivitis; however, owing to antibiotic overuse and misuse, bacterial resistance is increasing for this class of antibiotics, especially among older-generation fluoroquinolones. Fluoroquinolones have gained popularity in ocular therapy owing to their efficacy in the treatment of bacterial corneal ulcers, although many bacterial-resistant strains are also emerging in keratitis. Later-generation fluoroquinolones should be reserved for more severe cases of conjunctivitis. Older fluoroquinolones are effective for milder infections.

Regardless of the topical antibiotic regimen chosen, start off with a higher frequency of dosing (eg, q2h) for the first 1-2 days before decreasing the dosage (eg, qid) for the subsequent 5-7 days. Reiterate to the patient the importance of compliance with antibiotic drugs to ensure conjunctivitis resolution and especially to prevent bacterial resistance.

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.

Besifloxacin ophthalmic (Besivance)

Besifloxacin is a broad-spectrum fluoroquinolone antimicrobial ophthalmic suspension indicated for bacterial conjunctivitis approved for both children and adults to be used tid for 7 days. This agent is available as a 0.6% ophthalmic suspension. It has no human systemic formulation or animal use, thereby lowering the rate of bacterial resistance. Susceptible bacteria include CDC coryneform group G (Corynebacterium pseudodiphtheriticum, Corynebacterium stratum), H influenzae, Moraxella lacunata, S aureus, Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus lugdunensis, Streptococcus mitis, Streptococcus oralis, S pneumoniae, Pseudomonas aeruginosa, and Streptococcus salivarius.

Gatifloxacin ophthalmic solution 0.3% (Zymaxid)

A so-called 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, S epidermidis, S mitis, S pneumoniae, or H influenzae.

Moxifloxacin ophthalmic (Moxeza, Vigamox)

Moxifloxacin is another fourth-generation fluoroquinolone indicated for bacterial conjunctivitis due to H influenzae, S pneumoniae, and anaerobic bacteria. Compared to earlier-generation fluoroquinolones such as levofloxacin and ciprofloxacin, it is more effective against gram-positive bacteria and anaerobes. Moxifloxacin is self-preserved and, as such, contains no benzalkonium chloride (BAK) or other preservatives.

Levofloxacin ophthalmic

Levofloxacin is a third-generation fluoroquinolone and an S (-) enantiomer of ofloxacin. It inhibits DNA gyrase in susceptible organisms, thereby inhibiting relaxation of supercoiled DNA and promoting breakage of DNA strands. It has enhanced activity against S pneumoniae relative to earlier fluoroquinolone derivatives such as ciprofloxacin but is less effective than ciprofloxacin against gram-negative bacteria, especially P aeruginosa. It may also not be as effective against MRSA compared to moxifloxacin or gatifloxacin.

Ciprofloxacin ophthalmic (Ciloxan)

Ciprofloxacin is a second-generation fluoroquinolone that inhibits bacterial growth by inhibiting DNA gyrase. It is very commonly prescribed for a wide variety of systemic, cutaneous, respiratory, and genitourinary infections. 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 P aeruginosa. It may not cover all cases of S pneumoniae infection. Ciprofloxacin is the most effective of all fluoroquinolones against P aeruginosa infections, both superficial and systemic. Owing to its solubility profile, Ciloxan may leave precipitates because of its relative insolubility in corneal ulcers or epithelial defects, often imitating an infiltrate to the unaware observer. Ciprofloxacin is available as a topical ophthalmic, topical external auditory, and oral and IV preparation.

Ofloxacin ophthalmic (Ocuflox)

Ofloxacin is a second-generation fluoroquinolone. 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. Generic preparations are generally readily available.

Tobramycin ophthalmic (Tobrex)

Tobramycin is an aminoglycoside antibiotic that interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits, which results in a defective bacterial cell membrane. It has a narrow spectrum but is effective against gram-negative organisms, especially P aeruginosa, as well as many strains of MRSA and MRSE. It is available as a solution, ointment, and lotion and has been combined with steroids for combination antibiotic/steroid drops.

Gentamicin (Garamycin, Gentak)

Gentamicin is another commonly prescribed generic topical aminoglycoside antibiotic used for gram-negative bacterial coverage, including Pseudomonas and gram-positive Staphylococcus. Gentamicin is commercially available in solution or ointment form. Long-term or repeated use of topical aminoglycoside antibiotics can produce significant corneal toxicity, as well as resistant ocular-surface flora.

Trimethoprim/polymyxin B ophthalmic (Polytrim Ophthalmic Solution)

Polymyxin B is primarily used systemically for multidrug-resistant gram-negative organisms including P aeruginosa and is very ineffective against gram-positive organisms. In topical form, it is useful for broader gram-negative coverage. The trimethoprim component is generally effective against staphylococci and most gram-positive organisms, as well as some gram-negative aerobic bacilli and Escherichia coli. Because it is particularly effective against S pneumoniae and H influenzae, which affect primarily children, it is the antibiotic of choice in pediatric patients. The combination is an ophthalmic drop to be used q4h for 7-10 days.

Neomycin/polymyxin B/gramicidin ophthalmic (Neosporin Ophthalmic Solution)

Neomycin is an aminoglycoside antibiotic used for treatment of minor infections; it inhibits bacterial protein synthesis and growth. Polymyxin B disrupts the bacterial cytoplasmic membrane, permitting leakage of intracellular constituents and causing inhibition of bacterial growth. Neosporin is available as an ophthalmic ointment and a drop to be used q4h for 7-10 days.

Neomycin/polymyxin B/bacitracin ophthalmic (Neo-Polycin)

Neomycin has excellent activity against gram-negative organisms and partial activity against gram-positive bacteria. The combination with polymyxin B and bacitracin covers a broad spectrum of gram-positive, gram-negative, and anaerobic micro-organisms. This combination is available in ointment form because of the insolubility of the bacitracin constituent.

Azithromycin ophthalmic (AzaSite)

This second-generation ophthalmic macrolide antibiotic is indicated for bacterial conjunctivitis caused by CDC coryneform group G bacteria, H influenzae, S aureus, S mitis group, and S pneumoniae. It is especially effective against pediatric conjunctivitis owing to its efficient dosage regimen requiring only 9 drops of medication over 7 days. Clinical trials demonstrate superior efficacy with azithromycin in comparison to tobramycin. Its highly viscous mucoadhesive vehicle (Durasite) allows bid dosing the first 2 days and then qd for 5 more days. The decreased dosing allows for better patient compliance and hence quicker resolution of the conjunctivitis. Systemic and topical azithromycin have also exhibited anti-inflammatory properties through inhibition of the matrix metalloprotease 9 (MMP-9) pathway.

Erythromycin Ophthalmic (Ilotycin)

Topical erythromycin ointment is indicated for infections caused by susceptible strains of primarily gram-positive 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. Because of the high level of bacterial resistance to this antibiotic, it has limited clinical use and is available only in ointment form because of its insolubility.

Bacitracin Ophthalmic

Bacitracin prevents transfer of mucopeptides into growing cell wall, inhibiting bacterial growth. It a mixture of cyclic peptides that are effective against both gram-positive and gram-negative bacteria. Most cases of routine bacterial conjunctivitis will respond to bacitracin, including those caused by group A streptococci, S aureus, S pneumoniae, and H influenzae. It is a highly effective against gram-positive pathogens. Because it is available only in an ointment form because of its insolubility, the blurring of vision often limits its practical use to primarily off-label night-time–only prophylactic administration. It is not available systemically owing to nephrotoxicity.

Azithromycin (Zithromax, Zmax)

A 1-gram single dose, generally in combination with IM or IV ceftriaxone to cover N gonorrhea, is an effective treatment, as the drug of choice for adult inclusion (chlamydial) conjunctivitis concomitant to genitourinary chlamydial infection. Because chlamydial conjunctivitis must always be assumed to accompany genitourinary infection, systemic therapy is always indicated. This includes diagnostic confirmatory testing, as well as epidemiologic pursuit of all sexual contacts. Azithromycin has broad but shallow antibacterial activity effective against some gram-positive bacteria, some gram-negative bacteria, and many atypical bacteria. Systemic azithromycin is also widely used to treat routine upper and lower respiratory infections, usually in the form of the 5-day 6-pill Z-pack.

Doxycycline (Doryx, Vibramycin, Adoxa, Monodox)

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, Lyme disease, and a wide variety of respiratory and cutaneous infections. The dosage is 100 mg orally twice a day for 7 days for routine infections and 100 mg PO BID for one month to treat primary Lyme disease. In addition, doxycycline is frequently used for its anti-inflammatory, anti-MMP-9, and meibomian liquification properties in patients with cutaneous diseases such as rosacea, as well as for chronic blepharitis. Long-term administration in doses as low as 20 mg or 50 mg PO daily is often sufficient to control inflammation. Patients prescribed doxycycline and other tetracycline derivatives should always understand photosensitivity, gastrointestinal, and pregnancy precautions.

Erythromycin base (Ery-Tab, PCE, E.E.S.)

Erythromycin inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Oral erythromycin is effective in the treatment of chlamydial infections. Erythromycin base 500 mg orally four times a day for 7 days or erythromycin ethylsuccinate 800 mg orally four times a day for 7 days are effective treatments for chlamydial infections. Gastrointestinal side effects render erythromycin a secondary choice for chlamydial disease.

Levofloxacin (Levaquin)

Levofloxacin inhibits bacterial topoisomerase IV and DNA gyrase, which are required for bacterial DNA replication and transcription. This is the L stereoisomer of the D/L parent compound ofloxacin, the D form being inactive. Administer 500 mg orally once daily for 7 days for chlamydial infection. Levaquin is available in generic form and, along with ciprofloxacin, is among the most frequently prescribed oral fluoroquinolones used for respiratory and genitourinary infections.


Used to treat complicated and uncomplicated skin and skin structure infections, ofloxacin and other fluoroquinolones have an exceptional safety profile. Ofloxacin provides good monotherapy with extended coverage against Pseudomonas species, as well as excellent activity against pneumococcus. This agent acts by inhibition of DNA gyrase activity. The oral form has a reported bioavailability of 99%. Administer 300 mg orally twice daily for 7 days for chlamydial infections.

Ceftriaxone (Rocephin)

Ceftriaxone is a third-generation cephalosporin that arrests bacterial growth by binding to one or more penicillin-binding proteins. It has lower efficacy against gram-positive organisms but has excellent activity against susceptible pneumococcal organisms. It exerts an antimicrobial effect by interfering with the synthesis of peptidoglycan, a major structural component of the bacterial cell wall. It is highly effective against N gonorrhea as a single 1-gram dose. It is used IM and IV for a wide variety of cutaneous, respiratory, and genitourinary infections.

Penicillin G aqueous (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.