Prospective evaluation of external ocular microbial growth and aqueous humor contamination during cataract surgery.
OBJECTIVE
To analyze the route of aqueous humor contamination leading to the development of postoperative endophthalmitis.


METHODS
Department of Ophthalmology, University of Helsinki, Finland.


METHODS
Forty-nine eyes of 49 patients (31 having phacoemulsification and 18 extracapsular cataract extraction [ECCE]) participated in the study. Four bacterial cultures were taken: preoperative conjunctival swab, lid margin culture, intraoperative lacrimal lake sample, and immediate postoperative anterior chamber fluid sample.


RESULTS
Preoperative lid margin cultures were positive in 59.2% of eyes, conjunctival cultures in 69.4%, and lacrimal lake cultures in 24.9%. Four aqueous humor samples (8.2%) showed bacterial growth in the anterior chamber aspirate: 3 in the phacoemulsification and 1 in the ECCE group. The bacteria isolated in this study, Staphylococcus epidermidis and Propionibacterium acnes (2 positive isolates each) were sensitive to the preoperative topical antibiotics used. No aqueous humor sample or any from other locations showed gram-negative microbe growth. The most frequently recovered microbes in all samples collected from the 3 other sources were S epidermidis and other coagulase-negative staphylococcus species, followed by P acnes and other propionibacterium species. Staphylococcus aureus, and diptheroids.


CONCLUSIONS
The ocular surface significantly contributed to the transmission of microbes into the eye during cataract surgery. These microbes could not be eradicated by topical preoperative antibiotics. However, no patient developed postoperative endophthalmitis. Natural defense mechanisms appear to fend off a minor inoculum with these microbes of relatively low pathogenicity.
Tervo
T
T
Helsinki University Eye Hospital, Finland.
Ljungberg
P
P
Kautiainen
T
T
Puska
P
P
Lehto
I
I
Raivio
I
I
Järvinen
E
E
Kuusela
P
P
Tarkkanen
A
A
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001082:Aqueous Humor / Q000382:microbiology*; D001431:Bacteriological Techniques; D002387:Cataract Extraction / Q000009:adverse effects*; D015169:Colony Count, Microbial; D003228:Conjunctiva / Q000382:microbiology*; D009877:Endophthalmitis / Q000188:drug therapy / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000635:transmission; D005143:Eyelids / Q000382:microbiology*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000635:transmission*; D006801:Humans; D007765:Lacrimal Apparatus / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies
D000900:Anti-Bacterial Agents