Kenneth D. Thompson

Anterior Chamber Aspirate Cultures After Uncomplicated Cataract Surgery

We cultured anterior chamber aspirates of 30 patients who had uncomplicated extracapsular cataract extraction or phacoemulsification. The aspirate was obtained at the time of wound closure. Of 30 patients, 13 (43%) had culture-positive anterior chamber aspirates. The total number of organisms recovered was 18, with three patients having multiple organisms identified. The most commonly isolated organisms were coagulase-negative Staphylococcus sp., occurring in eight of 18 isolates (44%). No eyes in our study developed endophthalmitis, even though almost one half had viable organisms growing from the anterior chamber aspirates. Inoculum sizes were extremely small (10 to 20 colony-forming units/ml). This study suggests that in humans, the anterior chamber is capable of clearing a low inoculum of bacteria after cataract surgery without the development of endophthalmitis.

Plasmid labeling confirms bacterial translocation in pancreatitis

To examine whether the gut is a source of infection in acute pancreatitis, bacterial translocation and alterations of intestinal microecology and morphology were studied in 16 dogs. Dogs were colonized with a strain of Escherichia coli (E. coli 6938K) bearing the plasmid pUC4K, which confers kanamycin resistance. In eight dogs (group I), pancreatitis was induced by sodium taurocholate/trypsin injection. Eight other dogs (group II) underwent laparotomy only. The pancreas, mesenteric lymph nodes, peritoneal fluid, liver, and spleen were harvested 7 days later for culturing and histologic analysis. Identification of E. coli 6938K was accomplished by plasmid DNA analysis. Group I dogs had severe pancreatitis and ischemic changes in small bowel mucosa. Group II dogs had no changes. Translocation to the pancreas occurred in five dogs and to mesenteric lymph nodes in six dogs with pancreatitis. No translocation occurred in group II dogs (p < 0.05). In addition to E. coli 6938K, other gram-negative kanamycin-resistant species were isolated, including E. coli (other than 6938K) and Enterobacter cloacae. Enteric origin of these strains was confirmed by antibiography and plasmid DNA analysis. No overgrowth of cecal gram-negative bacteria was found. This study suggests that the gut is a primary source of infection in pancreatitis and that ischemic damage of intestinal mucosa may promote bacterial translocation.

In situ ELISA for the evaluation of antiviral compounds effective against human cytomegalovirus.

An in situ ELISA was developed as an improved procedure over the plaque reduction assay for antiviral susceptibility testing of HCMV. Unlike the plaque reduction assay, the ELISA can be completed at 4-5 days post-infection. The effective dose (ED50) of ganciclovir (GCV), acyclovir (ACV), phosphonoacetic acid (PAA), or phosphonoformic acid (PFA), was determined using HCMV strain AD169. The resistance profiles of two laboratory-derived GCV-resistant mutants of HCMV strain AD169 and seven clinical isolates were determined using the ELISA. The ELISA results were confirmed by the plaque reduction assay. The ED50 for GCV with the AD169 control ranged from 3.1 to 6.2 microM with a mean inhibitory concentration of 5.4 +/- 1.4 microM. Six of the clinical isolates were susceptible to GCV (ED50 = 3.1-6.2 microM). The seventh isolate had an ED50 of 50 microM and was resistant to GCV. This ELISA assay is reproducible and relatively simple to perform. The ELISA endpoints are clearly determined and the assay works well with a variety of antiviral compounds.

Intraocular gentamicin sulfate and postcataract anterior chamber aspirate cultures

Abstract We cultured anterior chamber aspirates of 28 patients who had uncomplicated cataract surgery. Fourteen patients had received 80 &mgr;g/ml of gentamicin in balanced salt solution through irrigation of the anterior chamber throughout cataract extraction, and 14 patients had received 8 &mgr;g/ml of gentamicin. Cultures of anterior chamber fluid obtained at the end of surgery from all 28 patients had no growth on two nonselective media. There was no clinical evidence of ocular toxicity. This study demonstrates that antibiotic in the intraocular irrigation fluid can reduce or eliminate the expected intraocular bacterial load after cataract surgery.

Changing technologies in immunodiagnosis: Enzyme immunoassays versus immunofluorescence assays

Abstract EIA methodology is rapidly superseding IFA as the technique of choice for serologic testing. Advantages include lower cost, economy of scale for large volume tests, ease of use, nonsubjective results, and greater accuracy and precision. Disadvantages include the requirement for new instrument purchase, lack of complete correlation with IFA, and lack of user familiarity with the results data if IFA titers are currently being used. Challenges to laboratorians interested in converting to EIA methodology include choosing equipment and test kits among the large and increasing number available, educating physicians in the new data expression, establishing the degree of correlation with IFA, and determining the significance of borderline or equivocal EIA results.

Tumorigenic Viruses Affecting the RES

The preceding chapters have dealt with the ways in which the mononuclear phagocyte system influences tumor development. Many of the avian and mammalian tumor viruses have been found to be immunosuppressive with concomitant changes in lymphoid organ morphology and in lymphoid cells. The discussion of immunosuppression by tumor viruses falls outside the subject of this review.