If one had an infection in the eyelid, would antibiotics like those
taken in capsules or intramuscularly work, given the LIMITED BLOOD
SUPPLY to the eyelid?  Would antibiotics in any form not applied
directly in the eye, such as eyedrops or ointment work for a) a
general bacterial infection of the eyelid b) a biofilm in
the eyelid ?  Assume the infection is normally susceptible to the
antibiotics that would given.

Hello - 

While I'm not KevinMD, I do have an MD - and I'll give the typical
disclaimer that this answer should not be substituted for medical
advice given by a treating physician.

Blepharitis is the medical term for inflammation of the eyelid
(whether infectious or not).  Infectious blepharitis is often caused
by staphylococcus species resident in the body (similar to many, if
not most infections of our outer coverings).

Most of the time, blepharitis will improve over time with proper
cleaning of the eye.  Sometimes, however, an infection will prolong
the healing and antibiotics may help with the resolution of this
condition.  Usually, topical antibiotics are the most common first
treatment, occasionally with steroids (this seems to be country
dependent) to reduce the inflammation.  Depending upon the cause,
site, and severity of the infection, oral antibiotics may also be
added.  You are correct in suggesting that the eyelid is not the best
perfused (little blood supply) part of the body, however, secretion of
antibiotic into the tears and the aqueous humor of the eye (the liquid
just behind the lens which also seeps out onto the surface of the eye)
is not negligible and may provide more thorough and consistent tissue
penetration than topical application alone (tetracycline family drugs
are most typically used for suspected bacterial infections -
erythromycin is more commonly used in children due to toxicity of
tetracyclines).  The meibomian glands may be the site of infection for
some cases of blepharitis and local secretion of antibiotic (delivered
via the bloodstream - usually tetracycline) may help resolve
infections as well.

Viral and fungal infections of the eyelid may also develop under
certain circumstances, but are far less common.

A brief review of blepharitis including pathophysiology (causes) and
treatments:  http://www.revoptom.com/handbook/sect1a.htm

The Merck manual section on blepharitis:
http://www.merck.com/pubs/mmanual/section8/chapter94/94b.htm

The Family Practice Handbook has a short blurb on blepharitis:
http://www.vh.org/adult/provider/familymedicine/FPHandbook/Chapter19/04-19.html

eMedicine.com has a short (and reasonably uninformative) section:
http://www.emedicine.com/aaem/topic49.htm

Please let me know if you would like further information.

synarchy

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Request for Answer Clarification by spark72-ga on 30 Apr 2003 15:32 PDT

Thankyou for your answer synarchy

Do you know how long one might have to take antibiotics orally
(capsules) to completely get rid of a moderate or severe bacterial
infection of the eyelid?  Six weeks or longer?  For example, if it was
Stenotrophomonas maltophilia (prev. known as pseudomonas maltophilia)
or related bacteria.

Also, my concern was that a biofilm of any bacteria in the eyelid
might be impossible to get rid of, because some germs would remain
beyond the reach of the antibiotic and develop resistance.

---

Clarification of Answer by synarchy-ga on 04 May 2003 11:30 PDT

Treatment regimens for eyelid infections severe enough to require oral
antibiotics may last for four to six weeks - the length of the
treatment is also dependent upon resolution of the clinical symptoms. 
Other complicating factors may lengthen the course of treatment. 
Immune compromise (HIV, some cancers, chemotherapy, etc) and eye
operations are the two most likely complicating factors.

S. maltophilia can be a difficult bug to treat due to it's lower
sensitivity (in some cases outright resistance) to aminoglycoside
antibiotics (ie gentamicin, a common topical agent), most beta-lactams
(penicillins/cephalosporins), and may or may not be resistant to
tetracyclines.  Cotrimazole and rifampin (both oral) are suggested by
several references, as are cefipime and sulfamethoxazole/trimethoprim;
although other treatments may be available and sensitivity testing
should be performed on cultures from the patient whenever possible:
http://wordnet.com.au/Products/diagnosis_management_infectious_diseases12.pdf
http://www.baysidehealth.org.au/uploads/general/Stenotrophomonas.pdf
http://www.ascp.com/public/pubs/tcp/2000/jan/cr_manage.shtml
http://www.emedicine.com/med/topic3457.htm

Antibiotic therapy in and of itself rarely will kill all bacteria -
the basic premise of the therapy is to reduce the bacterial load to a
level which can be handled by the patient's immune system - you are
correct that biofilms will complicate this as antibiotics will not
always penetrate the entire film - however, if the antibiotic is
available in sufficient concentrations in the fluid surrounding the
biofilm, it should retard the progression of the film growth, allowing
the body to resolve the infection.  Biofilms are not mentioned as
being a common problem with S. maltophilia infections - instead the
organisms natural resistance to many antibiotics complicates the
infection and may produce the conditions for an infection with S.
maltophilia in the first place as other competing bacteria are killed
off.

Please let me know if you have more questions.