André Péchinot

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.

Impact of previous sepsis on the accuracy of procalcitonin for the early diagnosis of blood stream infection in critically ill patients

BackgroundBlood stream infections (BSI) are life-threatening infections in intensive care units (ICU), and prognosis is highly dependent on early detection. Procalcitonin levels have been shown to accurately and quickly distinguish between BSI and noninfectious inflammatory states in critically ill patients. It is, however, unknown to what extent a recent history of sepsis (namely, secondary sepsis) can affect diagnosis of BSI using PCT.Methodsreview of the medical records of every patient with BSI in whom PCT dosage at the onset of sepsis was available between 1st September, 2006 and 31st July, 2007.Results179 episodes of either primary (n = 117) or secondary (n = 62) sepsis were included. Procalcitonin levels were found to be markedly lower in patients with secondary sepsis than in those without (6.4 [9.5] vs. 55.6 [99.0] ng/mL, respectively; p < 0.001), whereas the SOFA score was similar in the two groups. Although patients in the former group were more likely to have received steroids and effective antibiotic therapy prior to the BSI episode, and despite a higher proportion of candidemia in this group, a low PCT value was found to be independently associated with secondary sepsis (Odd Ratio = 0.33, 95% Confidence Interval: 0.16–0.70; p = 0.004). Additional patients with suspected but unconfirmed sepsis were used as controls (n = 23). Thus, diagnostic accuracy of PCT as assessed by the area under the receiver-operating characteristic curves (AUROCC) measurement was decreased in the patients with secondary sepsis compared to those without (AUROCC = 0.805, 95% CI: 0.699–0.879, vs. 0.934, 95% CI: 0.881–0.970, respectively; p < 0.050).ConclusionIn a critically ill patient with BSI, PCT elevation and diagnosis accuracy could be lower if sepsis is secondary than in those with a first episode of infection.

Bacterial epidemiology and antimicrobial resistance in ascitic fluid: a 2-year retrospective study.

The bacterial epidemiology of bacterascites and spontaneous bacterial peritonitis is evolving. Four hundred and eleven strains isolated from ascites in cirrhotic patients from 5 French hospitals were isolated in 2006 and 2007. Of these, 114 were definitely associated with spontaneous bacterial peritonitis. The proportion of Gram-positive and Gram-negative agents was quite similar, even after excluding coagulase-negative staphylococci, or when considering only definite spontaneous bacterial peritonitis or community-acquired strains. Staphylococci and Escherichia coli were the most frequent pathogens, but enterococci were also involved in nearly 15% of the cases. Among the E. coli, 28% were intermediate or resistant to amoxicillin+clavulanate, 5.3% expressed cephalosporinases or extended β-lactamases and 17.3% were intermediate or resistant to fluoroquinolones. Resistance to methicillin was observed in 27% of Staphylococcus aureus. Cefotaxime and amoxicillin–clavulanate remained the most effective ‘single’ agents, however on less than 70% of isolates. Some combinations (such as cefotaxime+amoxicillin) extended coverage to a further 15% of strains. Since inadequate empiric antibiotic therapy is associated with increased mortality, these combinations may be of great interest as first-line treatment, even though they may also lead to the development of antimicrobial resistance. Repeated epidemiological surveys and new clinical trials are thus needed.

Acute postoperative endophthalmitis caused by Staphylococcus lugdunensis.

ABSTRACT Acute postoperative endophthalmitis caused by Staphylococcus lugdunensis is infrequently reported in clinical studies. Five cases of acute postcataract surgery endophthalmitis caused by S. lugdunensis were taken from a multicenter prospective study conducted in four university-affiliated hospitals in France (2004 to 2005). These cases were characterized by severe ocular inflammation occurring with a mean delay of 7.6 days after cataract surgery, severe visual loss (hand motions or less in three cases), and dense infiltration of the vitreous. Each of these patients was initially treated by using a standard protocol with intravitreal (vancomycin and ceftazidime), systemic, and topical antibiotics. Given the severity of the endophthalmitis, even though bacteria were sensitive to intravitreal antibiotics, pars plana vitrectomy was needed in four cases. The final visual prognosis was complicated by severe retinal detachment in three cases. The microbiological diagnosis was reached by using conventional cultures with specific biochemical tests and eubacterial PCR amplification followed by direct sequencing.

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.

TEM-89 β-Lactamase Produced by a Proteus mirabilis Clinical Isolate: New Complex Mutant (CMT 3) with Mutations in both TEM-59 (IRT-17) and TEM-3

ABSTRACT TEM-89 (CMT-3) is the first complex mutant β-lactamase produced by a clinical strain of Proteus mirabilis (strain Pm 631). This new enzyme, which has a pI of 6.28, is derived from TEM-3 and has a single amino acid substitution also encountered in TEM-59 (inhibitor-resistant TEM β-lactamase IRT-17): Ser-130 to Gly. TEM-89 hydrolyzed penicillins to the same extent that TEM-3 did but lost almost all hydrolytic activity for cephalosporins and, like TEM-59, was highly resistant to inhibitors.

EVIDENCE OF IN VIVO TRANSFER OF A PLASMID ENCODING THE EXTENDED-SPECTRUM BETA-LACTAMASE TEM-24 AND OTHER RESISTANCE FACTORS AMONG DIFFERENT MEMBERS OF THE FAMILY ENTEROBACTERIACEAE

ABSTRACT The epidemiological study of several multidrug-resistantEnterobacteriaceae isolated from five patients demonstrated in vivo dissemination of a 100-kb plasmid encoding the extended-spectrum β-lactamase TEM-24 from a clonal strain ofEnterobacter aerogenes to different strains ofKlebsiella pneumoniae, Escherichia coli, Proteus vulgaris, Proteus mirabilis, and Serratia marcescens.

Staphylococcus aureus infective endocarditis versus bacteremia strains: Subtle genetic differences at stake.

Infective endocarditis (IE)((1)) is a severe condition complicating 10-25% of Staphylococcus aureus bacteremia. Although host-related IE risk factors have been identified, the involvement of bacterial features in IE complication is still unclear. We characterized strictly defined IE and bacteremia isolates and searched for discriminant features. S. aureus isolates causing community-acquired, definite native-valve IE (n=72) and bacteremia (n=54) were collected prospectively as part of a French multicenter cohort. Phenotypic traits previously reported or hypothesized to be involved in staphylococcal IE pathogenesis were tested. In parallel, the genotypic profiles of all isolates, obtained by microarray, were analyzed by discriminant analysis of principal components (DAPC)((2)). No significant difference was observed between IE and bacteremia strains, regarding either phenotypic or genotypic univariate analyses. However, the multivariate statistical tool DAPC, applied on microarray data, segregated IE and bacteremia isolates: IE isolates were correctly reassigned as such in 80.6% of the cases (C-statistic 0.83, P<0.001). The performance of this model was confirmed with an independent French collection IE and bacteremia isolates (78.8% reassignment, C-statistic 0.65, P<0.01). Finally, a simple linear discriminant function based on a subset of 8 genetic markers retained valuable performance both in study collection (86.1%, P<0.001) and in the independent validation collection (81.8%, P<0.01). We here show that community-acquired IE and bacteremia S. aureus isolates are genetically distinct based on subtle combinations of genetic markers. This finding provides the proof of concept that bacterial characteristics may contribute to the occurrence of IE in patients with S. aureus bacteremia.

Epidemiology and Antimicrobial Resistance of Streptococcus pneumoniae in France in 2007: Data from the Pneumococcus Surveillance Network

Antimicrobial resistance of Streptococcus pneumoniae in France is closely monitored by the pneumococcus surveillance network, founded in 1995, which collects data from regional observatories (Observatoire Régionaux du Pneumocoque [ORP]). In 2007, 23 ORPs analyzed the antibiotic susceptibility of 5,302 isolates of S. pneumoniae recovered in France from cerebrospinal fluid, blood, middle ear fluid, and pleural fluid, as well as from adult respiratory samples. The study showed that 38.2% of the strains were nonsusceptible to penicillin, 19.3% nonsusceptible to amoxicillin, and 10.5% nonsusceptible to cefotaxime. The percentage of pneumococcus nonsusceptible to penicillin varied according to both the sample and the age of the patient (child/adult): blood (27.8%/32.5%), cerebrospinal fluid (33.7%/34.6%), middle ear fluid (60.2%/27.5%), and pleural fluid (50.0%/31.0%). Between 2003 and 2007, the frequency of penicillin resistance in invasive pneumococcal disease gradually decreased from 46.4% to 29.0% in children and from 43.8% to 32.7% in adults. This decrease coincided with the introduction of a seven-valent pneumococcal conjugate vaccine into immunization programs and with a general reduction in levels of antibiotic consumption in France.

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.