The effect of ethnicity on anatomic success following macular hole surgery: a multicentre cohort study

PURPOSE

The purpose is to assess the effect of ethnicity on surgical macular hole closure.

METHODS

A retrospective cohort study was undertaken in five UK National Health Service Hospitals. We included all patients with known ethnicity undergoing vitrectomy, internal limiting membrane peel, and gas/oil tamponade for all stages of primary full-thickness macular hole (FTMH). The primary outcome was anatomic success, defined as FTMH closure with one operation. The secondary outcome was mean change in best-corrected visual acuity (BCVA) comparing baseline with final review.

RESULTS

Of 334 operations, the ethnicity profile comprised 78.7% White patients, 11.7% Black patients, 8.1% Asian patients, and 1.5% in mixed/other ethnicities. Mean age was 69.7 years with 68.5% females. Overall, 280 (83.8%) had anatomic success. Anatomic failure occurred in 38.5% of Black patients versus 12.6% of White patients (relative risk: 1.788; 95% CI: 1.012 to 3.159; P = 0.045). Overall, baseline logarithm of the minimum angle of resolution BCVA improved by 0.34, from 0.95 (95% CI: 0.894 to 1.008) to 0.62 (95% CI: 0.556 to 0.676). Mean BCVA improved by 0.35 in White patients, 0.37 in Black patients, 0.23 in Asian patients, and 0.38 in mixed/other ethnicity (P = 0.689). Greater FTMH minimum linear diameter was associated with an increased risk of anatomic failure (relative risk: 1.004; 95% CI: 1.002 to 1.005; P < 0.0001), whereas better pre-operative BCVA (F [1,19] = 162.90; P < 0.0001) and anatomic success (F [1,19] = 97.69; P < 0.0001) were associated with greater BCVA improvement. Socio-economic status did not significantly influence anatomic success or BCVA change.

CONCLUSIONS

Black ethnicity is associated with an approximately twofold greater risk of failed FTMH surgery. The reasons for this difference warrant further study.

Resolution of clonal subgroups among Neisseria gonorrhoeae IB-2 and IB-6 serovars by pulsed-field gel electrophoresis

OBJECTIVE

Analysis of macrorestriction patterns by PFGE to resolve the relatedness of clonal subgroups amongst N gonorrhoeae IB-2 and IB-6 serovar strains.

MATERIALS AND METHODS

Nineteen IB-2 and eight IB-6 serovar strains that differed in either auxotype or penicillin sensitivity were isolated over a two and a half-year period from patients attending several STD clinics in Sydney. During this period, a major clone, Wt/IB-2 (FS), established on epidemiological grounds, was circulating amongst homosexual males. The genetic relation of this major clone to the other strains present in the community was determined by pulsed-field gel electrophoretic (PFGE) analysis of DNA restriction fragments. Genomic DNA from the 27 isolates were prepared, digested with SpeI and BglII and the restriction patterns were analysed by contour-clamped homogeneous electric field electrophoresis (CHEF) in a CHEF DRIII equipment.

RESULTS

Phenotypic characterisation of the 27 isolates by the combined use of auxotype, serological characterisation and penicillin sensitivity indicated the presence of subgroups within each of the two serovars. In the present study, PFGE analysis of SPeI and BglII-generated genomic DNA restriction patterns from six of the ten Wt/IB-2 (FS) correlated well with phenotypic characterisation of this major clone. Four of the ten Wt/IB-2 (FS) were found to be clonally-derived variants of this major clone as minor genome variations (less than 3 DNA fragments) were observed. Distinct clones were represented by three Wt/IB-2 (LS) isolates as the DNA fingerprints generated from these were unrelated to the major clone. Analysis of PFGE patterns of 6 Pro/IB-2 isolates showed that one was genotypically identical to the major clone, two were clonal variants and three had significantly different patterns to indicate that they were genotypically unrelated. Wt/IB-6 isolates had heterogenous PFGE patterns that were clearly unrelated to the Wt/IB-2 serovar strains. Within the IB-6 serovar, there were three isolates with the Wt/IB-6 (FS) phenotype that could be considered as clonal variants whilst the rest were genotypically distinct.

CONCLUSIONS

PFGE analysis of macrorestriction patterns generated from SpeI- and BglII-cleavage of genomic DNA has enabled the establishment of clonal origins of strains present in the Sydney community during the period of study. The delineation of strains belonging to major A/S groups by PFGE analysis presents a clearer epidemiological picture than phenotypic characterisation alone.

Molecular typing of Neisseria gonorrhoeae by restriction fragment length polymorphisms

OBJECTIVE

To characterise Neisseria gonorrhoeae isolates by restriction fragment length polymorphisms (RFLPs) in ribosomal RNA genes.

DESIGN

Generation of RFLP patterns by HincII restriction of rRNA genes followed by hybridisation with a non-radioactive labelled broad spectrum 16 + 23S rRNA gene probe. This typing method was developed and compared with MAb based serotyping.

SPECIMENS

Forty three randomly collected isolates from Bangkok (27 isolates) and Singapore (16 isolates) were studied.

RESULTS

The RFLP patterns generated were reproducible and highly discriminatory between strains. Analysis of RFLPs produced by HincII restriction of rRNA genes established 9 patterns amongst the 43 isolates examined. Strains present within a common serovar could be further subdivided by RFLP typing. Identical RFLP patterns were found in some strains that belonged to various serovars.

CONCLUSION

RFLP typing based on heterogeneities of rRNA gene restriction patterns could be advantageously used to complement monoclonal antibody based serotyping for further subdivision of serovars. Higher sensitivity of this combined approach would enable better differentiation of strains in epidemiological studies.

Genetic relationships among Neisseria gonorrhoeae serovars analysed by multilocus enzyme electrophoresis

Multilocus enzyme electrophoretic analysis was employed to assess the genetic relatedness of Neisseria gonorrhoeae. Based on the diversity of electromorphs at 9 enzyme loci, 16 electrophoretic types (ETs) were established amongst the 65 isolates. The average number of alleles per enzyme locus was 1.7 and the mean genetic diversity per locus was 0.212. The majority of isolates belonged to either ET1 (32.3%) or ET2 (16.9%). No specific correlation of ETs was seen with serovars as the major types, ETs 1 and 2, were found distributed amongst the various serovars. Major serovars such as Bacjk (IB-1/2) and Bajk (IB-3/6) were each represented by 6 or 8 ETs respectively. Analysis of the genetic relationships of ETs to each other showed some clustering of subgroups that were more closely related than others.

Enzymatic characterization of Pseudomonas cepacia by API ZYM profile

The enzymatic activities of 53 strains of Pseudomonas cepacia were determined by using the API ZYM system. Strong alkaline phosphatase, acid phosphatase, butyrate esterase, caprylate esterase, myristate lipase, leucine arylamidase, and phosphoamidase activities were consistently detected in all strains. Weak activities were observed for valine arylamidase, beta-glucosidase, and N-acetyl-beta-glucosaminidase. No activities could be demonstrated for cystine arylamidase, trypsin, chymotrypsin, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, alpha-mannosidase, and alpha-fucosidase. Enzymatic activities of pseudomonads may provide useful information about their pathogenesis and information for identification of Pseudomonas species.

Enzymatic profile of clinical isolates of Acinetobacter calcoaceticus

The enzymatic profiles of 109 clinical isolates of Acinetobacter calcoaceticus subsp. anitratus and lwoffi were determined with conventional plate tests and the rapid API ZYM system (Analytab Products, Plainview, N.Y.). The majority of strains tested lacked DNase, hemolysin, protease, elastase and gelatinase. Strong enzymatic activities of butyrate esterase (C4), caprylate esterase (C8) and leucine arylamidase were detected in all isolates. No trypsin, chymotrypsin, alkaline phosphatase or glucosidase activities were present. This profile was characteristic of all isolates examined by the API ZYM system and could serve as a useful diagnostic feature of Acinetobacter calcoaceticus subsp. anitratus and subsp. lwoffi.