Year : 1982 | Volume
: 30 | Issue : 4 | Page : 205--207
Recent advances in therapy of ocular bacterial infections
LP Agarwal, HC Agarwal
All India Institute of Medical Sciences, New Delhi, India
L P Agarwal
All India Institute of Medical Sciences, New Delhi-110029
|How to cite this article:|
Agarwal L P, Agarwal H C. Recent advances in therapy of ocular bacterial infections.Indian J Ophthalmol 1982;30:205-207
|How to cite this URL:|
Agarwal L P, Agarwal H C. Recent advances in therapy of ocular bacterial infections. Indian J Ophthalmol [serial online] 1982 [cited 2020 Apr 4 ];30:205-207
Available from: http://www.ijo.in/text.asp?1982/30/4/205/29429
In the recent past many newer antibiotics have developed due to changing susceptibility of microorganisms, but almost incredibility serious charges have been advanced against the habitual and indiscriminate use of antibiotic prescriptions. There are very obvious reasons to believe that antibiotics are being over used as well as abused. The production of antibiotics in the recent past has increased many folds with heavy investments. It has been estimated that about 20 percent prescriptions contain one or the other antibiotic without fully satisfying oneself that antibiotic is necessary for the therapy. The incidence of drug reactions has increased many folds probably because a very large number of patients are being unnecessarily exposed to the hazards of antibiotics due to abuse or over use of antibiotics.
In the therapy of bacterial ocular diseases also, a large number of antibiotics acting locally alone or systemically also when absorbed after local administration, are being used. The antibiotics are used individually as well as in their various combinations to cover wider range of infective organisms and thus achieve quick therapeutic results. Many a time antibiotic therapy is combined with steroid therapy to decrease the inflammatory response and tissue damage.
The indiscriminate use of potent newer antibiotics such as chloramphenical, gentamycin, tobramycin, cloxacillin for trivial bacterial infections may lead to the development of resistant strains. Thus losing the opportunity for the use of such antibiotics for more serious ocular infections in subsequent future. At times the use of a combination of antibiotics which are incompatible such as a combination of gentamycin and chloramphenicol, or a combination of tobramycin and carbenicillin may lead to inactivation of both the antibiotics. Thus the use of such incompatible combinations may prove not only ineffective but dangerous leading to incurable ocular tissue damage and blindness.
The local use of newer antibiotics which are used parenteally for the treatment of systemic infections is often practised by ophthalmic physicians. This at times may lead to the development of hypersensitivity reactions such as fever, skin rashes, haematologic and hepatic disorders and even anaphylaxis. The direct toxicity reactions include nausea, vomiting diarrhoea, impairment of renal, hepatic, hemopoitic functions or damage to 8th cranial nerve. Suppression of normal microbial flora and super infection by drug resistant micro-organisms or continued infection with the initial pathogen through the emergence of drug resistant mutants is not very uncommon. The glaring example of changing sensitivity pattern as detected by invitro studies at our centre is examplified for pseudomonas aeruginosa. In the year 1977, 37/42 (80.0%) strains of pseudomonas were found sensitive to gentamicin and 35 (83.3% to framycetin whereas in 1978, 84/87 (96.6%) and 68/87 (78.2%) strains were found sensitive, only 72.4%, 43.7% and 11.5% strains were sensitive to polymyxin B, streptomycin and chloromycetin respectively. The picture seems to have changed during the years 1979-80. Last year, 51.1%, 36.0% and 28.1 %strains were recorded to be sensitive to gentamycin, streptomycin, polymyxin B and chloromycetin. Only 7.8% strains were sensitive to framycetin. In 1980, sensitivity has further altered. Only 32.0%, 36.0%, 44.0% and 26.0% of the strains are now sensitive to gentamycin, streptomycin, polymyxin B and chloromycetin. Sensitivity to framycetin has further reduced to 4.0%. Highest number of resistant strains have erupted from corneal ulcer cases. Two strains were resistant to all including tobramycin and colistin. However it seems that strains from sources other than eye still show better susceptibility to these antimicrobials. The local use of neomycin drops produces superficial punctate keratitis in a small percentage of cases; often produces contact dermatitis.
In the management of specific and nonspecific pseudotumours of the orbit, emperically systemic, antibiotic is given alongwith steroids. In such cases, the antibiotics such as tetracycline can produce pseudotumor cerebri, chlorarnphenicol can produce optic neuritis, sulphonamides produce transient myopia.
The usual treatment of intra-ocular infections consists of intensive use of systemic and topical antibiotic administration. Intra-cameral injection of antibiotics may lead to operative complications and drug irritations such as endothelial damage, iritis, neovascularisation, and cataract formation, but has the advantage of rapidly achieving a very high intra-ocular antibiotic concentration. The risk and benefit of such injection must be weighed in the management of an individual case.
The use of a particular type of antibiotic on clinical grounds without repeated efforts to isolate the organisms from the lesion is dangerous at times. The participation of two or more microorganisms in the infective process of which only one was thought of at the time of drug selection is again harmful.
It is generally believed by unwary practitioners that corticosteroids decrease the inflammatory response of the tissues but it should be borne in mind that these agents destroy thymocytes, slow leukocyte movement, inhibit scar formation by fibroblasts, melt away newly formed capillaries, and favour the growth of pathogenic fungi and other opportunistic organisms. Thus the use of steroids in case of bacterial corneal ulcers and post operative bacterial endophthalmitis is not entirely safe. Steroid induced glaucoma, cataract, delayed wound healing, are other very well known complications. The cortico-steroids are a double edged sword and must be used judiciously in the treatment of bacterial infections since they can incite own fraud of destructive eye diseases.
The decision to use a particular antibiotic for a given infection should not be guided by clinical impression, except for initial emergency treatment. Arbitrary choice of an antibiotic is unwise. The individual strains of microorganisms vary widely in their sensitivity. It is always essential for the selection of the best antibiotic to carry out laboratory sensitivity studies and prescribe the antibiotic accordingly. As far as possible for the topical use, the antibiotics commonly administered systemically should be avoided. Prophylactic use of antibiotics in the era of asepsis has no role to play.
In the recent past there has been great advancement in vitreous surgery. It is now possible to remove post-inflammatory debris and membranes from the vitreous. Thus restoring sight atleast in some cases of curable blindness which are due to bacterial infection of the posterior segment.
We may conclude by laying down some broad principles of use of antibiotics in ocular infections;
Avoid local use of antibiotics which are used systemically. Local use of such antibiotics produces drug sensitivity and may prove dangerous. This is the reason that we have recommended the banning of production of penicillin ointment for local use.Prophylactic use of antibiotics is only mentioned to be condemned irrespective of the spectrum of antibiotic.Combination of antibiotics with steroids should be weighed very carefully before therapeutically resorted.The principle for antibiotic and or corticoid therapy should be no drug is the best treatment and least medication is the best alternative. This in effect means a careful clinical and laboratory assessment of the indication of the use of a particular antibiotic and or corticoid before treatment.