|Year : 1995 | Volume
| Issue : 4 | Page : 191-194
Endophthalmitis caused by Anaerobic bacteria
Tarun Sharma, Lingam Gopal, Sunil Parikh, SS Badrinath, HN Madhavan, BN Mukesh
From Sankara Nethralaya and Vision Research Foundation, 18, College Road, Madras, India
Vision Research Foundation, 18, College Road, Madras 600 006
Source of Support: None, Conflict of Interest: None
A retrospective analysis of 22 patients who underwent pars plana vitrectomy for endophthalmitis and had culture-proven anaerobic bacteria, was done. Elimination of infection with attached retina and recovery of ambulatory vision ≥2/60 were considered as anatomic success and functional success, respectively. Mean follow-up period was 12.7 months (range, 2 to 48 months). Anatomic success was attained in 14 (63.6%) eyes and functional success in 12 (54.6%) eyes. A poor preoperative visual acuity was found to be associated with poor functional outcome (p < 0.046). In endophthalmitis, a routine anaerobic culture of intraocular specimen is recommended.
Keywords: Anaerobic bacteria - Endophthalmitis.
|How to cite this article:|
Sharma T, Gopal L, Parikh S, Badrinath S S, Madhavan H N, Mukesh B N. Endophthalmitis caused by Anaerobic bacteria. Indian J Ophthalmol 1995;43:191-4
|How to cite this URL:|
Sharma T, Gopal L, Parikh S, Badrinath S S, Madhavan H N, Mukesh B N. Endophthalmitis caused by Anaerobic bacteria. Indian J Ophthalmol [serial online] 1995 [cited 2021 Feb 27];43:191-4. Available from: https://www.ijo.in/text.asp?1995/43/4/191/25250
Endophthalmitis is a catastrophic complication of intraocular surgery, penetrating injury, and endogenous infection. The aetiologic agent in many cases is unclear, and routine aerobic bacterial cultures are often negative. With the advent of improved methods of isolation and identification of anaerobic bacteria from clinical specimens, interest has increased in defining the anaerobic bacteria of the normal flora and in assessing the role of anaerobes in endophthalmitis.
Jones and Robinson reported only ten cases of anaerobic endophthalmitis in 1977. This was followed by a report of 18 cases in 1986 by Ormerod et al. Herein, we present a retrospective evaluation of pars plana vitrectomy in 22 patients with culture-proven anaerobic endophthalmitis.
| Materials and methods|| |
The records of 22 patients who underwent pars plana vitrectomy for culture-proven anaerobic endophthalmitis during the period from 1990 to 1993, were reviewed. Of the 22 patients, 12 (54.6%) had developed endophthalmitis following intraocular surgery, 7 (31.8%) after penetrating injury and 3 (13.6%) had endogenous infection.
An undiluted vitreous specimen was collected in the operating room prior to vitrectomy for cytological and microbiological studies. After expelling air from the syringe containing vitreous specimen, the needle was capped and protected with a sterile rubber bung and transported immediately to the microbiology laboratory [Figure - 1]. Aspirates were inoculated directly onto bacteriological media, placing one to two drops on each medium. Anaerobic cultures were done by inoculation onto prereduced Brucella Blood Agar (BBA) supplemented with 10% sheep blood, haemin, cysteine and vitamin K; and into either thioglycollate broth supplemented with 10% normal horse serum or Roberston's cooked meat medium. The BBA plate was incubated in compact anaerobic work station (Don Whitley) at 37°C. The plate was inspected for growth every day for ten days after which it was discarded as sterile, if no growth was found. Specimens inoculated into thioglycollate broth or Roberston's cooked meat medium were also incubated at 37°C. On appearance of turbidity, the medium was sub-cultured onto two BBA plates, one of which was incubated aerobically and the other anaerobically. Each isolate growing on the anaerobic plates was identified by standard methods. [8, 9]
All patients underwent a three-port pars plana vitrectomy. Intravitreal antibiotics were injected that usually consisted of gentamicin (0.1 - 0.4 mg) or cefazolin (2.25 mg) and/or cephalosporidine (0.25 mg). In almost all patients, this treatment was supplemented with intravenous antibiotics. Besides topical antibiotics and steroids, systemic steroids (1 mg/kg body weight) were also given based on the clinical condition.
Anatomical success was considered when there was a total removal of infection with attached retina. Functional success was defined as a recovery of ambulatory vision of 2/60 or better. Mean follow-up was 12.7 months (range, 2 to 48 months). Fisher's exact probability test was used to identify the factors associated with functional success.
| Results|| |
Twenty-two patients (17 males and 5 females) with endophthalmitis involving anaerobic bacteria were identified. The mean age was 33.6 years (range, 4 to 75 years) and the median was 32 years. All the patients in the post-traumatic group were less than 10 years of age [Figure - 2]. The right eye was involved in 12 and the left eye in 10 patients.
Of the 12 eyes which developed endophthalmitis following intraocular surgery, 7 (58.3%) had undergone intracapsular cataract extraction, 3 (25%) extracapsular cataract extraction with intraocular lens implantation and 2 (16.7%) antiglaucoma operation. Of the 7 eyes which developed endophthalmitis following penetrating injury, the nature of injuring substance was organic matter, such as, thorn or wood in 5 (71.4%) and metallic in 2 (28.6%) eyes.
The onset of endophthalmitis was acute (within 24 to 48 hours) in 17 (77.3%) patients, sub-acute (within 2 to 7 days) in 2 (9.1%) and chronic (after 7 days or more) in 3 (13.6%) patients. Endophthalmitis developed on day 1 in 85.7% of patients after penetrating injury compared to 41.7% after intraocular surgery.
Preoperative visual acuity was light perception in 14 (63.6%) patients, hand motions in 4 (18.2%), 2/60 in 1 (4.5%) and 3/60 in 1 (4.5%) patient. In two patients, preoperative visual acuity could not be assessed due to young age. Of the three patients with pseudophakic endophthalmitis, intraocular lens was explanted in only one patient.
The microbiological data of the 22 patients are shown in [Table - 1]. Propionibacterium acnes (7 cases) and Bacteroides species (6 cases) were the commonest anaerobes isolated. Uncommon anaerobes included anaerobic streptococci (2 cases) and one case each of Clostridium perfringens, Fusobacterium necrophorum, Veillonella, B. ureolyticus, and Peptostreptococcus. Two anaerobes remained unidentified. Of the 7 eyes where both anterior chamber (AC) and vitreous were aspirated for microbiological evaluation, same organism was identified in 4 (57.1%). A positive culture from AC and negative culture from vitreous were present in 2 (28.6%). In one eye in which no growth was obtained from either source, evisceration had to be performed eventually and the specimen revealed anaerobic Streptococcus.
Anatomic success was achieved in 14 (63.6%) eyes. Functional success, i.e., visual acuity of 2/60 or better was attained in 12 (54.6%) eyes. Visual acuity of 6/60 or better was obtained in 10 (45.5%) eyes, 6/24 or better in 8 (36.4%), 6/18 or better in 6 (27.3%), 6/12 or better in 3 (13.6%) and 6/9 in 2 (9.1%) eyes.
Of all the variables which were analysed to identify the correlation with functional success, only one factor, i.e., preoperative visual acuity was found to be statistically significant. Only 42.9% of patients attained a postoperative visual acuity of 2/60 or better where the preoperative visual acuity was only light perception compared to 100% in eyes with preoperative visual acuity of hand motions or better (p < 0.046) [Table - 2]. No correlation was found with the type of endophthalmitis, its onset, time of surgical intervention and type of organisms. Of the 8 eyes which could not be salvaged, phthisis bulbi occurred in 6 eyes and 2 patients needed evisceration.
| Discussion|| |
The surface microbial flora of humans is predominantly anaerobic. [10, 11] In the conjunctiva, anaerobes may be as prevalent as aerobic bacteria. The pattern of anaerobic bacteria in the normal conjunctiva resembles that of the skin, with a predominance of propionibacteria and gram-positive anaerobic cocci. The pO2 of the central vitreous cavity is very low., Anaerobic bacteria might therefore cause endophthalmitis if introduced in sufficient numbers into the vitreous cavity from the conjunctiva during surgery or trauma.
In the present study, endophthalmitis was exogenous in 19 (86.4%) eyes and endogenous in 3 (13.6%) eyes. Of the 19 patients with exogenous endophthalmitis, 12 patients had intraocular surgery and 7 penetrating injury. Endophthalmitis was noted on day 1 after trauma in 85.7% of patients compared to 41.7% after intraocular surgery. Probably, more number of anaerobic bacteria gain entry into the eye after penetrating trauma, causing acute endophthalmitis. In patients with haematogenous dissemination, there was no obvious pattern of predisposition.
In the series reported by Jones and Robinson, polymicrobial infection was present in 8 of 10 patients (80%) whereas, Ormerod reported in only 32% of patients. No polymicrobial infection was noted in our series. None of the patients in the series of Jones and Robinson received intraocular antibiotic or underwent vitrectomy. Fifty percent attained visual acuities of 6/15 or better, probably reflecting the relatively low virulence of organism in this series. In contrast, 16 out of 18 patients reported by Ormerod underwent pars plana vitrectomy, and in 66.7% of eyes the visual recovery was 6/120 (20/400) or better. Our anatomic success of 63.6% and functional success of 54.8% compared well with these series. Visual acuity of 6/80 or better was attained in 45.5% of patients in our series.
No correlation could be made between preoperative factors and postoperative visual acuity in the earlier reports., However, we found that in patients with better preoperative visual acuity, the postoperative visual results were better.
Anaerobic bacterial endophthalmitis has therapeutic implications. P. acnes is most susceptible to penicillin, chloramphenicol, cefoxitin, cefotaxime and clindamycin. However, most anaerobes, including P. acnes, are resistant to gentamicin.
Based on the results of this study, we suggest that in endophthalmitis, an anaerobic aetiology should be suspected and the intraocular specimens should be cultured for both anaerobic and aerobic organisms.
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[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2]