How to: accreditation of blood cultures' proceedings. A clinical microbiology approach for adding value to patient care.

BACKGROUND: Quality assurance and quality management are driving forces for controlling blood culture best practices but should not be disconnected from the end-point target, i.e. patient value. AIMS: This article is intended to help microbiologists implement blood culture accreditation that is actually beneficial to patient management. SOURCES: Experience from a nationwide taskforce for promoting quality assurance and competence in clinical microbiology laboratories, guidelines on blood culture. CONTENT: Experience in blood culture accreditation according to International standard ISO 15189 standards is provided in this review, with a particular focus on critical points that are specific to blood culture (e.g. excluding strain identification or antimicrobial susceptibility testing). Blood culture test method verification is based on risk analysis, and evaluation of the test method's performance is based on the literature review and suppliers' data. In addition, blood culture performance relies largely on the quality of its pre-analytical phase, and the test method should be monitored based on key performance indicators such as the volume of blood cultured, the contamination rate and time to transportation. Other critical key indicators include the rate of false-positive signals, the rate of positive blood cultures, the ecology associated with positive results, and the timely communication of the results to the ward during the post-analytical phase. Finally, a critical analysis of quality controls and of the tools needed to improve blood culture monitoring in the future is provided. IMPLICATION: Appropriate quality assurance should focus on patient value rather than technical details to provide an appropriate clinical service.

[Detection of Staphylococcus aureus resistant to methicillin (MRSA) by molecular biology (Cepheid GeneXpert IL, GeneOhm BD, Roche LightCycler, Hyplex Evigene I2A) versus screening by culture: Economic and practical strategy for the laboratory]. / Dépistage de Staphylococcus aureus résistant à la méthicilline (SARM) par biologie moléculaire (Cepheid GeneXpert IL, GeneOhm BD, LightCycler Roche, Hyplex Evigene I2A) versus dépistage par culture : stratégie économico-pratique pour le laboratoire.

OBJECTIVES: Patients admitted in cardiac surgery and cardiac ICU at the Clinic Saint-Gatien (Tours) are screened for MRSA at the entrance by nasal swab and culture on blood agar and selective chromogenic medium made by addition of cefoxitin: BBL CHROMagar MRSA-II BD (result obtained at Day +1). We wanted to assess the molecular biology techniques available to obtain a result at day 0 for the majority of patients and to define an economic and practical strategy for the laboratory. TECHNIQUES: We studied four molecular biology techniques: Cepheid GeneXpert (Cepheid) GeneOhm (BD), LightCycler (Roche) and Hyplex (I2A). Upon reception, nasal swabs were treated by culture, considered as reference, and one of the techniques of molecular biology, according to the manufacturer's notice. We conducted four studies between April 2008 and February 2009 to obtain a significant sample for each of them. METHODS: By screening we mean a method that allows us to exclude MRSA carriage for patients waiting for surgery, and not to change patient management: for example, lack of isolation measures specific to entrance, no modification of antibiotic prophylaxis during surgery and no isolation measures in the immediate postoperative period. RESULTS: The criteria we considered for this evaluation were: (1) technician time: time to perform one or a series of sample(s) n=10 or more (about 2h for all techniques except GeneXpert 75min), level of skilled competences (no specific training for GeneXpert); (2) results: turnaround time (all molecular biology techniques), ease of reading and results interpretations (no specialized training required for GeneXpert), failure or not (12% of failure of internal controls for GeneOhm); (3) economic: cost for one or a series of sample(s) (n=10 or more), if we considered X as the reference culture cost (10 X Hyplex and LightCycler, 20 X and 40 X for GeneXpert GeneOhm); (4) NPV: 100% for GeneXpert and LightCycler. CONCLUSION: At same sensitivity, no technique, including culture, can solve alone our problem, which is: (1) get results at day 0 for batch of samples (n<10): all molecular biology techniques; (2) beyond 10 samples: LightCycler (Roche) automated or Hyplex (I2A) manual; (3) when the result at day 1 is sufficient, the use of chromogenic agar with a reading of less than 18h as BBL CHROMagar MRSA II (BD) remains the most economical; (4) to be sure that a patient admitted at Day 0, even at night's emergency, is not carrier of MRSA: only Cepheid GeneXpert technology (IL). Furthermore, Cepheid GeneXpert (IL) allows performing several tests in parallel. The rapidity of this system can help control the transmission and make better use of antibiotics.

[1997-2007, 10 years of monitoring the evolution of resistance of Streptococcus pneumoniae to antibiotics in the region Centre; review of the Pneumococcus network]. / 1997-2007, dix ans de suivi de l'évolution de la résistance de Streptococcus pneumoniae aux antibiotiques en région Centre; bilan de l'observatoire du pneumocoque.

Regional pneumococcal observatories in region Centre, created in 1997, participate with the others pneumococcal observatories alongside the National Reference Center for Pneumococci and the Institut de Veille Sanitaire at the monitoring of the evolution of resistance of pneumococci to antibiotics in France. Between 1997 and 2007, 2427 strains of Streptococcus pneumoniae were isolated in part from cerebrospinal fluids, blood and middle ear fluid, from children and adults. The prevalence of pneumococci with a decreased susceptibility to penicillin (PDSP) decreased strongly in region Centre: 56.8 % in 2001, 39.6 % en 2007. These data are similar to the French national data over the same period.

[The Pneumococcal Observatory for the Central Region, 1 April 1999 to 31 March 2000]. / Observatoire du Pneumocoque de la Région Centre, du 1er avril 1999 au 31 mars 2000.

Seven hundred and ninety six strains of pneumococcus were collected in the Centre region, from 15 laboratories, between 1st April 1999 and 31st of March 2000. Data were processed, using 4th dimension software, and concerned age, file number, consultation/hospitalisation, sample type, susceptibility to oxacillin (5 micrograms), results of the E-test for benzylpenicillin, amoxicillin, cefotaxime and results of the routine disc diffusion test. Strains with reduced susceptibility to benzylpenicillin (PRSP) were collected by the co-ordinating centre to perform MICs by the reference agar dilution test and serotyping. Out of 796 strains, 450 strains (56.7%) were categorised as PRSP and 400 of them were studied by the co-ordinating centre. Forty two percent of the samples originated from lungs, followed by 19.5% from blood samples, 15% from ear pus (85.7% PRSP) and 2.5% from CSF. Thirty nine percent of the patients were female. 36.6% were children under sixteen (70.1% PRSP) and 62.4% were adults (49.2% PRSP). Out of 400 PRSP 106 (26.5%) were characterised as resistant and 294 (73.5%) as intermediate to benzylpenicillin. Compared to the agar dilution test, 90% of the PRSP studied by E-test had a MIC value for benzylpenicillin within +/- 1 dilution. Thirty six strains of PRSP were resistant to amoxicillin (9% of the PRSP) and 10 (2.5% of the PRSP) to cefotaxime. Serotyping was done on 375 strains. The serotypes encountered were the following: 23 (26.9%), 14 (22.1%), 19 (19.5%), 6 (12.8%), 9 (9.9%) and 15 (5.1%).

[The Pneumococcus Observatory of the Central Region, from June 1, 1997 to May 31, 1998]. / Observatoire du pneumocoque de la région Centre, du 1er juin 1997 au 31 mai 1998.

714 pneumococcus were listed from 14 laboratories between the 1 June 1997 and the 31 May 1998. Data capture was done on Epi info software and concerned age, file number, consultation/hospitalization, sample type, susceptibility to oxacilline (5 micrograms), the results of the E-test for penicillin G, amoxicillin, cefotaxime and the results of the routine disk diffusion susceptibility method. Strains with reduced susceptibility to penicillin G (PRSP) were collected by the coordinating center to perform MICs by the reference method of agar dilution and serotyping. Over 714 strains, 45.7% of the samples originated from lungs, followed by 22% for blood samples, 14% for ear pus and 2.3% for CSF. 34% of the patients were female. 36.7% were children under 16 (57.8% PRSP) and 63.3% were adults (41% PRSP). 338 strains (47.3%) were determined as PRSP and 293 of them were studied by the coordinating center. 81 of the 293 PRSP (27.7%) were resistant et 212 (72.3%) were intermediate to penicillin G. 81% of the PRSP studied had a CMI value for penicillin G within +/- 1 log2 dilution. 20 strains of PRSP were resistant for amoxicillin (6.8% of the PRSP) and two (0.7% of the PRSP) for cefotaxime. 289 serotyping were done, most met serotypes were 23 (25%), 14 (23%). The least met was 15 (2.4%). These results let assess the epidemiology of pneumococcus in our region.

[Evaluation of a new and rapid antibiotic sensitivity method testing for Enterobacteriaceae responsible for urinary infections]. / Evaluation d'une nouvelle méthode d'étude rapide de la sensibilité aux antibiotiques des entérobactéries responsables d'infections urinaires.

URIFAST Es et Es Plus (International Microbio, Signes, France) are rapid antimicrobial susceptibility testing method in broth medium without using an automatic reader. A screening assay (URIFAST Quatro 1C ou URIFAST Twin 1C) is performed with a 4 or 9 antimicrobial agents with a concentration c' below the low critical concentration (c) defined by the Comité de l'Antibiogramme de la Société Française de Microbiologie (CA-SFM). When a bacterial strain is presumed resistant, an antimicrobial susceptibility test with the two critical concentrations (CA-SFM) can be performed with 5 or 10 antimicrobial agents antibiotiques (URIFAST Twin ABG ou URIFAST ABG). 140 strains of Enterobacteriaceae from urinary tract infections; E. coli (n = 94), P. mirabilis (n = 13), K. pneumoniae (n = 4), K. oxytoca (n = 6), C. diversus (n = 3), P. vulgaris (n = 1), M. morganii (n = 3), C. freundii (n = 4), E. aerogenes (n = 2), E. cloacae (n = 5) and S. marcescens (n = 5); were isolated with CPS ID2 (bioMérieux, Marcy l'Etoile, France). URIFAST results were compared to Rapid ATB Ur et ATB Ur results obtained after reading with ATB expression (bioMerieux). For each discrepancy, the minimal inhibitory concentration (MIC) by agar dilution was used as the reference method. Agreement obtained were 98.57% with Quatro 1C, 98.40% with Twin 1C, 98.14% with Twin ABG and 98.39% with ABG. 94% of beta-lactams susceptible Enterobacteriaceae were detected by the screening tray with the antimicrobial agent concentration c'. URIFAST Es et Es Plus are standardized and easy-to-use methods. Because of their good performances, the URIFAST methods can be used to test antimicrobial susceptibility for Enterobacteriaceae from urinary tract infections.

[Informative capacity of 8 serological tests in the diagnosis of human brucellosis]. / Capacité informative de huit tests sérologiques dans le diagnostic de la brucellose humaine.

Assessment of the informative value of 8 immunological tests: sero-agglutination (Wright and Rose Bengale), indirect immunosorbent assay, counter immuno electrophoresis, ELISA IgG, IgM and IgA, and particle counting immunoassay (PACIA) has been performed among the results of serum of 209 patients. The patients were divided in four groups: 71 who already had brucellosis, 18 Yersinia infections, 12 Tularemia and 108 free of desease. The informative capacities of a positive result of counter immuno electrophoresis (Protein antigen Brucellin-INRA Tours-Nouzilly) is higher than others reactions and can be proposed as a confirmatory test of brucellosis. Among others techniques, 4 were found to be more sensitive: Elisa IgA (se = 97.6) and IgG (se = 90.1), IFI (se = 91.5) and Rose Bengale (se = 85.9) and can be proposed as screening test for medical diagnosis or epidemiological survey. Many cross-reactions were observed specially with Yersinia enterocolitica even with new serological methods.

[Brucellosis among occupationally exposed people: evaluation of immunological tests after vaccination]. / Brucellose en milieu professionnel exposé: évaluation des tests immunologiques après vaccination.

For the evaluation of immunological tests during an epidemiological survey and of vaccination with the PI brucellin vaccine, in an occupationally exposed environment, a sample group of 354 subjects was studied. The vaccinal strategy was based on the outcome of a skin test for hypersensitivity: the PS brucellin test. In this framework, the serological status and evolution of individuals with positive or negative reactions to this test were analysed. Sera were studied using the buffered antigen test, indirect fluorescence immunoassay and Wright's agglutination test, as well as by PACIA and ELISA techniques with assay of IgG, IgA and IgM antibodies. The PS test, which was pivotal in this study, was compared with the lymphoblastic transformation test. One prominent aspect of this evaluation was the establishment of conventional prognostic indices for the PS and serology. The PS is definitely shown to be a convenient, reliable tool for screening. Although it does not generate sensitivity it may modify the serological status of both positive and negative individuals.

[Brucella vaccination in professionally exposed subjects. Prospective study]. / Vaccination brucellique en milieu professionnel exposé. Etude prospective.

This prospective phase IV study on cohort concerns a vaccine made of the phenol-insoluble fraction of Brucella abortus biotype 1 (B19 strain). Three hundred and three professionally exposed subjects entered the study; 161 out of 182 subjects (88.5 percent) with negative response to an intradermal test for detection of previous contamination accepted to be vaccinated. Booster injections were given 18 and 36 months after vaccination. Local pain was observed after 45.2 percent of injections and moderate systemic reactions after 5 percent of injections. Seropositivity after primary vaccination reached 80 percent. The booster injection, justified by a major decrease of this rate after 18 months, gave exactly the same response of the thymo-independent type. This vaccinal schedule did not result in detectable hypersensitivity. The clinical effectiveness of the vaccine could not be evaluated accurately because of the insufficient number of subjects. The possibility of subclinical infection in vaccinated subjects calls for wider comparative studies of vaccinated versus non-vaccinated subjects.

[Evaluation of Clinitek in the screening and optimisation of the diagnosis of urinary tract infection]. / Evaluation du Clinitek dans le dépistage et l'optimisation du diagnostic de l'infection urinaire.

A study was conducted to compare the interest of using Clinitek and leucocytes esterase, blood, nitrites strip Multistix-8 SG (Ames-Bayer Diagnostics) with conventional method (dilution of urine in agar plate) and with automated system (Autobac) as a screening procedure to detect significant bacteriuria. The results are expressed in terms of sensitivity, specificity, predictive value of a negative and positive test. A total of 1303 urine samples were tested of which 730 (56%) were founded negative with Clinitek or conventional urine analysis (Se = 83.6%; VPN = 89.6%). Criteria for urinary tract infection were present for 193 samples (14.8%), the predictive value of a negative test for leucocytes, blood or nitrites (99.6%) justifies the use of Clinitek for economical screening of urine. Overall agreement is higher with the results or Clinitek (in few seconds) than with the Autobac (in 4-5 hours) when compared to the conventional method. The authors propose Clinitek as an effective method for screening and optimised urine analysis for urinary tract infection.

[Evaluation of a screening test for urinary infection]. / Evaluation d'un test de dépistage de l'infection urinaire.

The interest of using a reagent strip (Multistix-8 SG, Ames, Miles Laboratories) as a screen for urinary tract infection was evaluated in a clinical study involving several sites and 2,183 adult urine specimens of which 340 were infected. The results are expressed in terms of sensitivity, specificity, predictive value of a negative and positive test. The predictive value of a negative test for nitrites in combination with leucocytes (97.5%) justifies the use of the reagent strip in eliminating non-infected urine.

[Human brucellosis in Benin: results of a serological survey among exposed workers]. / La brucellose humaine au Bénin: résultats d'une enquête sérologique chez des travailleurs exposés.

A serological survey was carried out in Bénin in order to assess the rate of brucellosis infection among exposed workers (workers in slaughtering-houses and breeders). 221 sera were tested with rose Bengale test, Wright sero-agglutination test, indirect immunofluorescence test and counter-immuno electrophoresis (brucelline). The percentage of positive sera among exposed workers is 17,7%. The rose Bengale and immunofluorescence tests combination permits complete detection of positive sera. These results suggest the existence of human brucellosis in Bénin and shows the necessity of a national control programme adapted to the socio-economic problems of this country.

[Antibiotic sensitivity of bacteria isolated from pathological specimens and utilization of beta-lactams in an orthopedic surgery service]. / Sensibilité aux antibiotiques des bactéries isolées de produits pathologiques et consommation de bêtalactamines dans un service de chirurgie osseuse.

From 1980 to 1984, computerized data on the sensitivity to the main antibiotics of 1991 strains isolated from clinical specimens were evaluated in relation to beta-lactam use and hospital activity in a unit of orthopedic surgery. No major variations were found in distribution of species throughout the study period, whereas sensitivity to antimicrobial agents changed. From 1980 to 1982, patients had postoperative prophylactic treatment with cephalosporin (cefazolin) for two days; during the same period, 59% of 557 Gram negative organisms were resistant to cefazolin and 31% of Staphylococci were resistant to methicillin (and to other antibiotics). In 1983 and 1984, cefazolin was replaced by intraoperative flash therapy with a penicillin-M (cloxacillin); concomitantly, sensitivity to cefazolin increased among Gram negative organisms (38% of 485 isolates were cefazolin-resistant; p less than 0.001) and Staphylococci (16% of 342 isolates were methicillin-resistant; p less than 0.001). Phage typing of S. aureus failed to disclose any epidemic outbreak. Since hospital activity remained the same throughout the period under study, it seems justified to correlate the increase in bacterial sensitivity observed to the decrease in use of cephalosporin, although other factors (microepidemic, isolation techniques) may be involved.

[Development of the sensitivity to antibiotics in strains of Neisseria gonorrhea isolated in Touraine over a 5-year period]. / Evolution de la sensibilité aux antibiotiques des souches de Neisseria gonorrhoeae isolées en Touraine depuis cinq ans.

347 Neisseria gonorrhoeae strains isolated in Touraine, France, from December 1978 to March 1984 were tested for susceptibility to seven antibiotics using an agar dilution method. Percentage of strains with a penicillin G MIC = 0.06 micrograms/ml rose from 58% in 78-80 to 69% in 82-84. Consistent amoxicillin MICs were found throughout the survey (MIC 50: 0.125 and MIC 90: 0.5 micrograms/ml). Three penicillinase-producing strains were recovered from patients contaminated outside the study area. For tetracycline, minocycline, chloramphenicol and spectinomycin, variations of MICs 50 and 90 did not exceed one dilution either way. For spiramycin, MICs 50 and 90 fell from 2 and 8 micrograms/ml respectively in 78-80 to 1 and 2 micrograms/ml in 82-84. Our findings show that susceptibility of Gonococci to the main antibiotics used for treating gonococcal infections in our area has not changed significantly over the last five years. Moreover, implantation and diffusion of penicillinase-producing strains has failed to occur.

[Antibiotic therapy of pneumopathies in intensive care and protected distal bronchial samples]. / Antibiothérapie des pneumopathies en réanimation et prélèvement bronchique distal protégé (PBDP).

Bacteriology was performed on 57 specimens collected by the Wimberley protected catheter bronchoscopy technique (PCB) from 42 ventilated patients with severe head trauma hospitalized in the neurosurgical intensive care unit to determine the etiology of their pneumopathy. All patients had a nasotracheal tube upon arrival at the intensive care unit. For each sample, smears were examined and cultures under aerobic and anaerobic conditions as well as with CO2 were performed. In 34 (59%) of the 57 cases, examination of smears allowed rapid diagnosis and appropriate chemotherapy. In 47 (82%) cases, culture was positive, with a single pathogen being recovered in half of cases. The most prevalent organisms among the 75 species isolated were S. aureus (38%), P. aeruginosa (15%), Klebsiella (12%), Haemophilus (8%), and Pneumococcus (9%). Consistency with positive cultures of blood or pleural effusion samples was recorded in 92% of cases. Narrow spectrum antibiotic therapy can be chosen according to the results of PCB bacteriology and rapid automated antibiotic sensitivity testing obtained within 24 hours. PCB is therefore recommended in pulmonary infections in intensive care units.