Healio
Healio
ByEduardo Alfonso, MD
June 01, 2008
5 min read
Save

Newer-generation fluoroquinolones treat external eye infection

ByEduardo Alfonso, MD

Newer-generation fluoroquinolones play a major role in the treatment of bacterial conjunctivitis because these agents act quickly against a broad spectrum of pathogens, including most of the bacteria that could be causative agents for bacterial conjunctivitis. The advantages of the newer-generation fluoroquinolones moxifloxacin (Vigamox, Alcon Laboratories, Inc.) and gatifloxacin (Zymar, Allergan) are that they have faster eradication rates,1,2 are more effective against resistant organisms, and are less disposed to organisms developing resistance to them3-6 when used as directed (ie, a 3- to 5-day treatment protocol). They are preferred over the older-generation fluoroquinolones in the treatment of bacterial conjunctivitis, and they should not be used longer than the indicated time because of the possibility for developing resistance. By selecting optimal dosing regimens for the newer antibiotics, clinicians can avoid treatment failures and can help prevent the emergence of further antibiotic resistance.7

Bacterial conjunctivitis is common, especially in young patients, and usually has social and economic consequences by disrupting the affected patient’s patterns of daily living.8-11 The disease may lead to absenteeism from school and work and also impact communities.1 Patients benefit from treatment with a newer-generation fluoroquinolone that provides fast relief of symptoms and a rapid reduction of the pathogen flora. In a 2006 study, 1 moxifloxacin was shown to eradicate Streptococcus pneumoniae in vitro faster than did other older antibiotics such as tobramycin, gentamicin, and polymyxin B-trimethoprim. Use of moxifloxacin may allow for faster clinical remission of symptoms and limit the spread of the disease.

Eduardo Alfonso, MD
Eduardo Alfonso

In February 2008, Balzli and colleagues12 published study results comparing moxifloxacin and gatifloxacin using a rabbit model of post-LASIK methicillin-resistant Staphylococcus aureus (MRSA) keratitis. Both moxifloxacin and gatifloxacin were effective in treating established infections, but moxifloxacin demonstrated significantly greater prophylactic efficacy.

Epidemics can develop with viral conjunctivitis, especially with the adenovirus, the enterovirus, and the Coxsackie virus. The newer fluoroquinolones should not be used as a primary treatment for nonbacterial conjunctivitis such as epidemic viral keratoconjunctivitis. I recommend that these newer agents be used only in patients who may have a secondary bacterial infection. Other nonantibiotic therapies such as artificial tears or a short course of anti-inflammatories such as topical corticosteroids are effective for treating viral conjunctivitis.

The newer-generation fluoroquinolones are also effective against the gram-negative organisms that cause corneal ulcers.
—Eduardo Alfonso, MD

Patients with viral conjunctivitis should remain in isolation until the conjunctivitis is resolved. This may take from 7 to 14 days. Fluoroquinolones should be used only in patients with suspected secondary bacterial infection.

Efficacy against gram-negative organisms

The newer-generation fluoroquinolones are also effective against the gram-negative organisms that cause corneal ulcers, which are primarily Pseudomonas, Serratia and Klebsiella. However, all fluoroquinolones have a slight gap in coverage of gram-positive organisms, specifically Streptococci and MRSA, although newer-generation fluoroquinolones are more effective than previous generations of fluoroquinolones against these pathogens.13-15 Therefore, if a patient presents with a large central corneal ulcer, a fortified antibiotic such as topical vancomycin should be used in addition to a newer-generation fluoroquinolone to treat Streptococci and MRSA. However, if a patient presents with a peripheral small ulcer in which there is no suspicion of MRSA or Streptococci, a newer-generation fluoroquinolone alone may be adequate to eradicate the infection. Newer-generation fluoroquinolones also achieve high concentrations in the cornea, potentially leading to greater effectiveness in treating corneal ulcers.16

I recommend that ophthalmologists guide any therapy with cultures, if possible. If a culture is performed on a peripheral small ulcer and the results show MRSA or Streptococci, surgeons should treat the patient with fortified vancomycin therapy in addition to the newer-generation fluoroquinolone.

The newer-generation fluoroquinolones are effective against most other common bacteria that cause corneal ulcers. If an ulcer does not respond to fluoroquinolone therapy, surgeons should consider that the cause of infection may be an unusual organism such as Mycobacteria species or a nonbacterial organism such as a fungus or acanthamoeba. For these patients, treatment must be altered and directed toward these organisms.

Patients with fungal ulcers should be treated according to the type of fungus. If the fungus is filamentous, I recommend that surgeons administer topical natamycin (Natacyn, Alcon Laboratories, Inc.). If the fungus is nonfilamentous, therapy can include initial treatment with natamycin followed by other treatments such as oriconazole, amphotericin, fluconazole, or ketoconazole.

Patients with acanthamoeba ulcers must be treated with extemporaneously prepared antiamoebic medication, such as propamidine or polyhexamethylene biguanide hydrochloride.

References

  1. Lichtenstein SJ, Dorfman M, Kennedy R, Stroman D. Controlling contagious bacterial conjunctivitis. J Pediatr Ophthalmol Strabismus. 2006;43:19-26.
  2. D’Arienzo PA, Brunell PA, Rhee R, Wagner RS. Advances in treatment of ocular infections in children. Presented at the 16th Annual Infectious Diseases in Children Meeting; Nov. 22, 2003, New York, NY.
  3. Vigamox ophthalmic solution [package insert]. Fort Worth, TX: Alcon Laboratories, Inc; 2007.
  4. Tankovic J, Bachoual R, Ouabdesselam S, Boudjadja A, Soussy CJ. In-vitro activity of moxifloxacin against fluoroquinolone-resistant strains of aerobic gram-negative bacilli and Enterococcus faecalis. J Antimicrob Chemother. 1999;43(suppl B):12-23.
  5. Schedletzky H, Wiedemann B, Heisig P. The effect of moxifloxacin on its target topoisomerases from Escherichia coli and Staphylococcus aureus. J Antimicrob Chemother. 1999;43(suppl B):31-37.
  6. Balfour JA, Lamb HM. Moxifloxacin: a review of its clinical potential in the management of community-acquired respiratory tract infections. Drugs. 2000;59:115-139.
  7. Schlech BA, Alfonso E. Overview of the potency of moxifloxacin ophthalmic solution 0.5% (Vigamox). Surv Ophthalmol. 2005 Nov;50 (suppl 1):S7-15.
  8. Martin M, Turco JH, Zegans ME, et al. An outbreak of conjunctivitis due to atypical Streptococcus pneumonia. N Engl J Med. 2003;348:1112-1121.
  9. Centers for Disease Control and Prevention. Outbreak of bacterial conjunctivitis at a college: New Hampshire, January-March 2002. MMWR. 2002;51:205-207.
  10. Minnesota Department of Health. Outbreak of conjunctivitis due to Streptococcus pneumoniae. Disease Control Newsletter. 2004;32:6-8.
  11. Centers for Disease Control and Prevention. Pneumococcal conjunctivitis at an elementary school: Maine, Sept. 20-Dec. 6, 2002. MMWR. 2003;52:64-66.
  12. Balzli CL, McCormick CC, Caballero AR, et al. Fluoroquinolone therapy in a rabbit model of post-LASIK methicillin-resistant Staphylococcus aureus keratitis. J Cataract Refract Surg. 2008;34:295-301.
  13. Allen GP, Kaatz GW, Rybak MJ. In vitro activities of mutant prevention concentration-targeted concentrations of fluoroquinolones against Staphylococcus aureus in a pharmacodynamic model. Int J Antimicrob Agents. 2004;24(2):150-160.
  14. Mather R, Karenchak LM, Romanowski EG, Kowalski RP. Fourth generation fluoroquinolones: new weapons in the arsenal of ophthalmic antibiotics. Am J Ophthalmol. 2002;133:463-466.
  15. Miller D. Review of moxifloxacin hydrochloride ophthalmic solution in the treatment of bacterial eye infections. Clin Ophthalmol. 2008;2(1).
  16. Holland EJ, Lane S, Kim T, et al. Human cornea and aqueous humor concentrations of moxifloxacin and gatifloxacin following topical ocular dosing with Vigamox solution or Zymar. Invest Ophthalmol Vis Sci. 2006;47:E-Abstract 3577.