Pierre-Loïc Cornut

Eubacterial PCR for bacterial detection and identification in 100 acute postcataract surgery endophthalmitis.

PURPOSE To evaluate eubacterial PCR compared with conventional cultures for detection and identification of bacterial agents in ocular samples from patients with acute postcataract endophthalmitis. METHODS Broad-range eubacterial PCR amplification was used, followed by direct DNA sequencing in ocular samples (aqueous humor, vitreous samples from tap or vitrectomy) from 100 consecutive patients presenting with acute postcataract endophthalmitis. Bacterial cultures were performed on the same ocular samples by using traditional methods (brain-heart infusion broth). RESULTS At the time of admission, the detection rate was not significantly different between cultures and PCR (38.2% for cultures versus 34.6% for PCR in aqueous humor samples; 54% versus 57% in vitreous from a vitreous tap). In contrast, in the vitreous obtained from vitrectomy, after intravitreous injection of antibiotics, PCR detected bacteria in 70% of the cases, compared with 9% in cultures. By combining PCR and cultures, bacterial identification was obtained in 47% of aqueous humor samples at admission, in 68% of vitreous samples from a vitreous tap at admission, and in 72% of vitreous samples from pars plana vitrectomy. Gram-positive bacteria predominated (94.3%). The concordance between cultures and PCR was 100%. The contamination rate was 2%. CONCLUSIONS Cultures and eubacterial PCR are complementary techniques for bacterial identification in eyes with acute postcataract endophthalmitis. PCR technique was needed for identification of the involved microbial pathogen in 25% of all the cases. Eubacterial PCR is more effective than cultures in detecting bacteria in vitreous samples from patients with previous intravitreous administration of antibiotics.

Prospective study of corneal collagen cross-linking efficacy and tolerance in the treatment of keratoconus and corneal ectasia: 3-year results.

Purpose: To assess the efficacy and tolerance of corneal collagen cross-linking with corneal epithelium debridement in the stabilizing treatment of primary or secondary corneal ectasia. Methods: Prospective, comparative, single-center study of patients presenting with progressive primary or secondary corneal ectasia. The control group, comprising the fellow eye of patients with bilateral involvement, was followed up for 6 months and then treated. The parameters examined were the biomicroscopic examination, visual acuity [best spectacle–corrected visual acuity (BSCVA) and uncorrected visual acuity (UCVA)], keratometry of the central 3 mm, intraocular pressure, central pachymetry, endothelial density, and macular profile. Results: Fifty-five eyes of 39 patients were treated; the mean follow-up period was 20.8 ± 6.8 months (range, 12–36 months). The control group comprised 16 eyes. UCVA and BSCVA were significantly improved between 3 and 12 months, reaching their minimum at 6 months, varying from 0.12 UCVA to 0.07 BSCVA (P < 0.05). These values and the keratometry values did not vary significantly after 36 months of follow-up. In contrast, analysis of the control group revealed significant keratometric deterioration of +1.2 diopters at 6 months (P < 0.05), with no further significant variation after treatment. Analysis of the subgroups of patients with post–laser in situ keratomileusis ectasia confirmed these results. At the end of the study, intraocular pressure, pachymetry, and endothelial density were not significantly modified, and no macular profile modification was observed. Conclusion: This study shows that corneal collagen cross-linking can stabilize progressive corneal ectasia, both primary and secondary, with no induced iatrogenic effects.

Polymerase chain reaction identification in aqueous humor of patients with postoperative endophthalmitis

PURPOSE: To identify bacterial agents in the aqueous humor of patients with postoperative endophthalmitis using eubacterial polymerase chain reaction (PCR) and conventional culture. SETTING: University Hospital of Lyon E. Herriot, Lyon, France. METHODS: Broad‐range eubacterial PCR amplification followed by direct sequencing was used to identify microbial pathogens in ocular samples from 30 patients with acute or delayed‐onset endophthalmitis, mainly after cataract surgery. Ocular samples included aqueous humor collected before the first intravitreal injection of antibiotics and vitreous samples collected at the time of the therapeutic pars plana vitrectomy. RESULTS: Cultures were positive in 32% of cases and PCR in 61% of cases with aqueous humor samples. When associated, culture and PCR of aqueous humor samples allowed for a microbiological diagnosis in 71% of cases. Microorganisms cultured by conventional techniques matched those identified by PCR. When applied on vitreous pretreated with intravitreal antibiotics, PCR increased the identification rate from 18% to 62%. CONCLUSIONS: Polymerase chain reaction assay of initial aqueous humor samples contributed to the diagnosis of endophthalmitis in 30% of cases. Previous use of intravitreal antibiotics did not seem to affect the ability to PCR‐amplify DNA in the short term. Polymerase chain reaction‐based technology was a useful adjunct to conventional culture because when used with aqueous humor samples only, the association of both techniques allowed for a microbiological diagnosis in 71% of cases of postoperative acute and delayed‐onset endophthalmitis.

Relationship between baseline clinical data and microbiologic spectrum in 100 patients with acute postcataract endophthalmitis.

Purpose: To correlate the initial ocular presentation with bacterial identification in 100 patients with acute postcataract endophthalmitis. Methods: This was a prospective multicenter study. Demographic data, medical history, and the initial eye examination data were recorded on a standardized form. The relationship between bacterial identification and clinical factors at baseline was studied using univariate and multivariate analyses. Results: One hundred patients were admitted to the hospital with a median delay of 6 days after cataract surgery. The main symptoms were loss of vision (94.9%) and pain (75.5%). Major clinical signs were hypopyon (72%), pupillary fibrin membrane (77.5%), and loss of fundus visibility (90%). Baseline factors significantly associated with microbiologic identification were as follows: diabetes mellitus, a shorter delay of onset, initial visual acuity limited to light perception, higher intraocular pressure, chemosis, pupillary fibrin membrane, loss of the red reflex, and reduced fundus visibility. As compared with other bacteria, the identification of Streptococcus species (n = 19) was more frequently associated with male gender, diabetes mellitus, initial visual acuity limited to light perception, and pain. The Staphylococcus aureus and Staphylococcus lugdunensis group (n = 14) differed from other coagulase-negative Staphylococcus groups (n = 33) in that those patients had greater hypopyon height. Conclusion: The baseline features of acute endophthalmitis after cataract surgery in the era of phacoemulsification are similar to those reported in the Endophthalmitis Vitrectomy Study 15 years ago and differ according to the bacterial species. The association between the clinical signs and the microbiologic identification suggests that initial characteristics other than visual acuity may be useful in identifying patients presumed to be infected with a virulent species.

Baseline Factors Predictive of Visual Prognosis in Acute Postoperative Bacterial Endophthalmitis in Patients Undergoing Cataract Surgery

IMPORTANCE Although rare, postoperative endophthalmitis in patients undergoing cataract surgery can lead to anatomical or functional loss of the eye. Therapeutic strategies such as antibiotic prophylaxis and microbiological diagnosis are more effective with a target patient population. New prospective data are needed to identify prognostic factors. OBJECTIVE To identify baseline factors of visual prognosis in patients with acute bacterial endophthalmitis after cataract surgery. DESIGN Prospective study of consecutive patients undergoing cataract surgery, enrolled from March 1, 2004, through December 31, 2005. We analyzed outcomes to determine the effect on the final visual outcome, defined as poor (visual acuity [VA] worse than 20/100) or good (VA 20/40 or better) using univariate and multivariate analysis. SETTING Four academic hospitals. PARTICIPANTS Ninety-nine consecutive patients with cataract. INTERVENTION Corneal phacoemulsification. MAIN OUTCOMES AND MEASURES Factors related to the cataract surgery (complications), initial clinical presentation, and microbiological diagnosis and the final VA. RESULTS The significant baseline factors (at presentation) for good visual outcome (45% of the series) were the winter season, absence of complications during cataract surgery, initial VA, microbiological investigations revealing no microorganism or a coagulase-negative Staphylococcus species (CNSP), and fundus visibility. Quantitative factors associated with a good clinical prognosis were shorter duration of cataract surgery, younger age, and a hypopyon no greater than 1.5 mm. Significant factors associated with poor visual outcome were infection of the right eye, initial VA, corneal edema, a hypopyon larger than 1.5 mm, detection of bacterial species other than a CNSP, and the absence of fundus visibility. Multiple logistic regression analysis showed that high bacterial virulence was the only independent factor (odds ratio, 14.0 [95% CI, 2.7-71.0]; P = .001) for poor visual outcome. On the other hand, low bacterial virulence (odds ratio, 0.2 [95% CI, 0.03-0.6]; P = .01) and the absence of complications during cataract surgery (0.1 [0.01-0.4]; P = .003) were independent factors for good VA. CONCLUSIONS AND RELEVANCE Most clinical outcome factors in acute postoperative endophthalmitis can be identified at presentation. The bacterial virulence level is the main factor predictive of the final visual prognosis.

A multicentre prospective study of post-traumatic endophthalmitis

Purpose:  Study the clinical and microbiological characteristics and the prognostic factors of post‐traumatic endophthalmitis.

Analysis of diluted vitreous samples from vitrectomy is useful in eyes with severe acute postoperative endophthalmitis.

PURPOSE This study was designed to compare the diagnostic yield of microbiological analysis performed on diluted and undiluted vitreous samples from pars plana vitrectomy (PPV) in patients with acute postcataract endophthalmitis. DESIGN Cohort study, evaluation of diagnostic test or technology. PARTICIPANTS Patients with acute postcataract endophthalmitis (<6 weeks). METHODS Undiluted and diluted vitreous samples were taken from 34 consecutive patients at the beginning of PPV as part of the multicenter prospective study of the French Institutional Endophthalmitis Study (FRIENDS) group. Vitrectomy was performed after 1 (n = 12) or 2 (n = 22) intravitreous antibiotic injections. McNemars nonparametric test was used to compare culture and polymerase chain reaction (PCR) results between diluted and undiluted samples. MAIN OUTCOME MEASURES Rate of positivity of conventional culture (brain heart infusion broth) and eubacterial PCR tests from undiluted and diluted vitreous samples. RESULTS The microbiological analysis of both undiluted and diluted vitreous samples detected and identified a bacterial pathogen in 26 out of 34 cases (76.4%). The analysis of undiluted and diluted vitreous at the time of PPV, using eubacterial PCR and conventional culture, gave similar results (P = 0.99; McNemar test). However, eubacterial PCR was more sensitive than culture in detecting bacteria in vitreous at the time of PPV (76% vs 6%; P = 0.001; McNemar test). The difference in sensitivity between the 2 techniques was primarily associated with false-negative culture results for undiluted samples (2/3 of cases), mainly for coagulase-negative staphylococci. CONCLUSIONS The microbiological results obtained combining PCR and culture techniques were similar for diluted vitreous and undiluted vitreous analysis. When eubacterial PCR is available, sampling diluted vitreous, an easier procedure, may replace sampling undiluted vitreous.

Detection of Treponema pallidum in Aqueous Humor by Real-time Polymerase Chain Reaction

Purpose: To report the additional clinical value of real-time Polymerase chain reaction (PCR) in the detection of Treponema pallidum in aqueous humor. Methods: A real-time (RT) PCR assay targeting the polymerase 1 gene of Treponema pallidum was performed in aqueous humor samples collected in consecutive patients with ocular syphilis. Results: Five patients presenting with optic neuritis (1), posterior placoid chorioretinitis (1), or panuveitis with retinitis (3) were tested. The PCR results were positive in the 3 cases of panuveitis and negative in the 2 other cases. Conclusion: RT-PCR for Treponema pallidum in aqueous humor is useful to confirm syphilitic panuveitis.

Principles and applications of molecular biology techniques for the microbiological diagnosis of acute post-operative endophthalmitis

The systematic microbiological evaluation of endophthalmitis allows the confirmation of the infectious nature of the disease and the possible adaptation of treatment at the individual level and, at the collective level, the epidemiological characterization of the bacterial spectrum of endophthalmitis. Long reserved for research, the use of molecular biology techniques to complement conventional culture techniques has become important for the diagnosis of endophthalmitis in recent years. These new diagnostic techniques are particularly useful for the microbiological study of bacteria that are difficult or impossible to grow because of their intrinsic properties, their presence in only a small inoculum, their sequestration on prosthetic materials, or their inactivation by prior antibiotic treatment. These techniques are based on the polymerase chain reaction (PCR), which allows the amplification and detection of extracted bacterial deoxyribonucleic acid (DNA) that is initially present in minute quantities in an ocular sample. In practice, these conventional or real-time PCRs allow either the a priori detection of bacterial DNA (universal PCR) or the identification of a specific DNA fragment of a bacterial genus or species (specific PCR). New techniques of PCR will allow more rapid bacterial identification and also characterization of genotypic properties, such as genes of virulence or antibiotic resistance.

Microbiologic identification of bleb-related delayed-onset endophthalmitis caused by moraxella species.

PurposeTo report the clinical presentation and outcome of delayed-onset endophthalmitis caused by Moraxella species and to evaluate the eubacterial polymerase chain reaction (PCR) in aqueous humor samples for the microbiologic diagnosis. Patients and MethodsSeven patients with bleb-related delayed onset-endophthalmitis caused by Moraxella were included in a prospective multicenter study (FRIENDS group, 2004 to 2005). Eubacterial PCR followed by direct sequencing and conventional cultures were carried out on aqueous humor samples taken before the first intravitreal antibiotic injection and on vitreous samples taken during pars plana vitrectomy. ResultsAll cases were postoperative (5 after filtering surgery and 2 inadvertent filtering blebs). The mean delay of onset of endophthalmitis was 41.3 months±30.4 (SD) (range, 2.4 to 84.8) after surgery. Initial visual acuity was limited to light perception for 3 patients, hand motions for 2 patients, count fingers for 1 patient, and 20/125 for 1 patient. Functional recovery was variable with final visual acuity ranging from no light perception to 20/25. The eubacterial PCR carried out on aqueous humor provided microbiologic identification in all cases, whereas the cultures were negative in 6 of 7 cases. The eubacterial PCR performed on vitreous samples of 3 vitrectomized patients, after 2 intravitreal injections of antibiotics, identified Moraxella in 2 patients, whereas cultures were negative in all cases. ConclusionsDelayed-onset endophthalmitis caused by Moraxella occurs predominantly after a bleb-related infection. PCR is a more sensitive technique for the microbiologic diagnosis in this context than conventional culture.