Topography-based screening for previous laser in situ keratomileusis to correct myopia

PURPOSE: To demonstrate the feasibility of developing a screening tool based on corneal topography to detect previous myopic laser in situ keratomileusis (LASIK). SETTING: Clinical data from a private clinic analyzed in a university setting. METHODS: Two hundred thirty-three topographies were randomly selected so 1 topography per patient was used: 150 from unoperated corneas and 83 from corneas that had LASIK to correct myopia. The mean surgical correction was -4.40 diopters (D) +/- 2.53 (SD) (range -11.00 to -0.38 D). All topographies were performed using an Orbscan II unit (Bausch & Lomb Surgical). The LASIK procedures were performed using a Technolas 217C excimer laser and a Hansatome microkeratome (Bausch & Lomb Surgical). The algorithms used the mean value of the directional derivative (DT) of the anterior tangential curvature of the cornea in the 2.2 mm radius central disk and the mean value of the anterior elevation (E) with respect to the best-fit sphere in the 0.5 mm radius central disk. Topographies in the testing set (n = 119) were classified as operated if E < 0 (E algorithm) or DT > 0 (DT algorithm) or as unoperated. RESULTS: The E algorithm yielded 0% false positives and 16.7% false negatives and the DT algorithm, 6.5% and 7.1%, respectively. For myopia greater than -1.12 D, the DT algorithm provided a 0% false negative rate. The performance of E and DT algorithms, used in combination, was superior to clinical assessment. CONCLUSION: Criteria based on Orbscan II corneal topography are proposed for the detection of previous myopic LASIK performed with a Technolas 217C excimer laser.     

Détection fortuite de <Emphasis Type="Italic">cmy</Emphasis>-2 et <Emphasis Type="Italic">dha</Emphasis>-1 chez des isolats d’<Emphasis Type="Italic">Escherichia coli</Emphasis> producteurs de BLSE au Sénégal

Cephalosporinases, which are naturally present in some enterobacterial species, can be mobilized by transposons, migrate to plasmids, and spread into other species such as Escherichia coli. The aim of this study was to characterize genes responsible for the production of extended-spectrum β-lactamases (ESBL) in E. coli isolates from urinary origin isolated in two hospitals in Senegal. Thus, a fortuitous discovery of plasmidic cephalosporinase in two isolates was noted. One of the isolates produced dha-1 associated with ESBL CTX-M-14, the other produced cmy-2, ESBL CTXM-15, tem-1 penicillinase, and oxa-1. This confirms the circulation of multidrug-resistant bacteria producing plasmidic cephalosporinase in Senegal. However, a large study is needed to better understand the prevalence and the nature of the genes involved.     

IS1R-Mediated Plasticity of IncL/M Plasmids Leads to the Insertion of blaOXA-48 into the Escherichia coli Chromosome

The OXA-48 carbapenemase is mainly encoded by ∼62-kb IncL/M plasmids. However, chromosome-mediated genes have been observed in Escherichia coli isolates. In this work, we investigated the genetic environment of OXA-48 in members of the family Enterobacteriaceae (n = 22) to understand how the OXA-48-encoding gene is transferred into the E. coli chromosome. The OXA-48-encoding gene was located within intact Tn1999.2 transposons in the ∼62-kb plasmids or within a truncated variant of Tn1999.2 for the OXA-48-encoding genes located in the chromosomes of E. coli bacteria. The analysis of the Tn1999.2 genetic environment revealed an inverted orientation of the transposon in five ∼62-kb plasmids (5/14 [35%]) and in all chromosome inserts (n = 8). The sequencing of pRA35 plasmid showed that this orientation of Tn1999.2 and the acquisition of an IS1R insertion sequence generated a 21.9-kb IS1R-based composite transposon encoding OXA-48 and designated Tn6237. The sequencing of a chromosomal insert encoding OXA-48 also revealed this new transposon in the E. coli chromosome. PCR mapping showed the presence of this element in all strains harboring an OXA-48-encoding chromosomal insert. However, different insertion sites of this transposon were observed in the E. coli chromosome. Overall, these findings indicate a plasticity of the OXA-48 genetic environment mediated by IS1R insertion sequences. The insertion sequences can induce the transfer of the OXA-encoding gene into E. coli chromosomes and thereby promote its persistence and expression at low levels.     

The Candida albicans Ddr48 protein is essential for filamentation, stress response, and confers partial antifungal drug resistance.

BACKGROUND: Candida albicans is a dimorphic pathogenic fungus that causes mucosal and systemic infections. C. albicans pathogenicity is attributed to its ability to exist in different morphologic states and to respond to stress by up regulating several key genes. DDR48 is a stress-associated gene involved in DNA repair and in response to antifungal drug exposure. MATERIAL/METHODS: One allele of DDR48 was knocked out by homologous recombination that inserted a marker cassette in its position. Furthermore, reintroducing DDR48 on a plasmid created a revertant strain. Strains were grown on filamentation inducing and noninducing media, subjected to an oxidative stress challenge, injected into mice to assess virulence, and assayed for antifungal susceptibility by the E-test method. RESULTS: DDR48 was found to be haploid insufficient and possibly essential, since only a heterozygote, but not a homozygous, null mutant was generated. The mutant was filamentation defective on all hyphal media tested including serum and corn meal agar. Discrepancies in drug resistance profiles also were present: compared with the parental strain, DDR48/ddr48 heterozygote strain was susceptible in a dose-dependent manner to itraconazole and fluconazole and susceptible to ketoconazole. The mutant also appeared to be hypersensitive to a potentially lethal hydrogen peroxide challenge. However, no reduction in virulence of the mutant was observed. CONCLUSIONS: The present findings provide evidence that DDR48 is essential for filamentation, stress response, and possibly viability of C. albicans, making it a prime target for antifungal drug design.     

Impact of heads-up display imaging on endoscopic task performance

BACKGROUND AND PURPOSE: Heads-Up Imaging goggles provide ergonomic advantages to the endourologist. This study was designed to evaluate whether heads-up display impacts task performance for ureteroscopic stone retrieval. MATERIALS AND METHODS: The ability to capture a 5-mm calculus with a Cook N-Circle 2.2F stone basket from an inanimate caliceal model was tested by three experienced and three novice stone-basket operators. Visual display for initial testing for each operator was randomized to the OptiVu HD3 Heads-Up googles or a 20- inch Sony Triniton monitor (TV). Subsequent testing alternated between the two devices. Camera input was provided by the Storz telecam SL-NTSC. The HD3 was set up to align the direction of view with the operator's hands, while the TV was aligned at an angle 45 degrees lateral and 30 degrees superior to the operator's direction of view to approximate the traditional room set-up for an endourologic procedure. Each operator performed five basketing trials with each display set-up. RESULTS: Expert operators retrieved calculi more rapidly (9.2 +/- 5.9 seconds) than novice operators (50.7 +/- 48.9 seconds), irrespective of whether a TV monitor or goggle display was utilized as the imaging modality. No significant differences were noted in task performance between the two imaging modalities for the expert (P = b0.60), novice (P = 0.77), or overall (P = 0.91) groups. CONCLUSION: The Optiview Heads-Up goggle display system does not offer advantages in task performance with specific regard to the ability to capture stone fragments with baskets.     

Virulence factors and TEM-type β-lactamases produced by two isolates of an epidemic Klebsiella pneumoniae strain

Two Klebsiella pneumoniae isolates of the same strain, identified in Poland, produced either TEM-47 or TEM-68, which differed by the Arg275Leu substitution. They harbored a few virulence factors, including an iron-chelating factor and capsule overproduction, suggesting that these factors were sufficient to enhance their nosocomial potency. TEM-68 and TEM-47 had similar enzymatic activities, but TEM-68 was less susceptible to inhibitors than TEM-47. These results confirm the role of the Arg275Leu substitution in the evolution of TEM enzymes.