Real life turnaround time of blood cultures in the clinical microbiology laboratory: results of the first Italian survey, May 2015

Background and aims: Blood culture (BC) results are essential to guide antimicrobial chemotherapy for patients with sepsis. However, BC is a time-consuming exam, which can take several days. Reducing BCs turn around time (TAT) could impact on multiple outcome parameters and TAT monitoring is an important tool for measurement of microbiology laboratory performance. The aim of this study was to provide an overview of BC TATs among Italian microbiology laboratories. Materials and methods: Five laboratories collected and recorded, for a month period, date and time of the BC processing events. Cumulative TATs were analysed using the GraphPad software. Results: Participating laboratories reported data from 302 sepsis episodes. The median time from when the BC system produced a positive signal until Gram-stain results were reported was 7.6 hours. A rapid molecular identification and antimicrobial susceptibility testing (AST) was performed in 26.5% of BCs. Mean TAT for identification report was significantly lower when a molecular approach was adopted (12 vs. 28.7 hours, P<0.001). Similarly, results of the molecular AST were obtained more than 24 hours in advance compared with phenotypic AST (mean 13.2 vs. 47.6, P<0.001). TATs from BC positivity of laboratories opened 7 days/week were not significantly lower than those of laboratories opened 6 days/week. Conclusions: BC is a time-consuming exam, however, molecular identification and AST methods can drastically reduce time to results. The lack of difference between TATs observed for laboratories working 7 days/week and 6 days/week, coupled with a high rate of BCs turning positive during the night enable to conclude that the most urgent measure to reduce TATs is the expansion of laboratory regular duty hours

The answer of the Bacteriology Laboratory to new clinical needs. Rapid sepsis diagnotics at the Novara hospital

Faster microbiological responses are increasingly necessary in modern medicine and the Laboratory of Microbiology must be equipped in this sense. New instrumentation and, above all, a new approach by the Clinical Microbiologist that puts a focus on the real needs of the patient before the microbiological may allow for significantly improving the TAT of these diagnostics. The use of both new methodologies, new tools and revisited old technologies may mean less these days as it was obtained at the Laboratory of Microbiology and Virology of Novara, where the combined use of molecular biology techniques, and mass spectrometry techniques rapid growth have allowed for more than 36 hours to shorten the response time by positivization of blood cultures. Such an approach allows an important support to the clinician with obvious benefits for the patient

Identification using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry: Preliminar Data

Bacterial identification is usually allowed analyzing the phenotypic and biochemical topics of microorganisms. The traditional methods of identification require about 18-24 hours and are expensive. Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) allows the identification of bacteria in few minutes. We consider 459 bacterial strains that were identified both with MALDI TOF MS and VITEK-2. The percentage of concordance in every group of bacteria was more than 99%, at genus level were more than 94% and at species level was more than 92%. These preliminary data show that MALDI-TOF MS allows a rapid and precise microorganism identification

Hospital epidemiology and antibiotic resistance in clinical isolates of Enterobacter cloacae

In thIe latter years Enterobacter cloacae has been counted as a very important occasional pathogen, above all in causing hospital infections.The micro-organism’s interesting increases because of its high resistance in vitro to many antimicrobial agents. For this reason it would be possible to find out others resistance mutant phenotypes. The results (2000-2001 and the first six months of 2002), carried out 341 isolated samples from hospital patients, show that the percentage of these E. cloacae is little more than 1%, increasing prevalence of patients belonging to General Surgery and Intensive Care Unit. The susceptible tests suggest (without important differences during the whole year) that most of the clinical isolates have moderate or high level resistance to various antimicrobial agents (penicillins, cephalosporins, aminoglycosides, quinolones, monobactam) and almost all were susceptible to amikacin, carbapenems (imipenem) and trimethoprim/sulfmamethoxazolo. Always regarding the resistance of these pathogens, it was possible to find out some phenotypes, and one of these, among 172 isolates belonging to Intensive Care Unit, was a particular multiresistance phenotype. The VITEK ESßL detection test and the conventional double disk synergy test for detection of ESßL find out some phenotypes showing expression of stably derepressed beta-lactamase

Phylogenetic relationships, virulence factors and Rep-PCR epidemiological analysis of E. coli from human sources

The potential of Escherichia coli to cause of extra-intestinal infections was studied on a group of 94 clinical isolates. In this work, 32 E. coli isolates from urinary tract infections, 25 from bacteraemia, 12 from low respiratory tract infections, and 25 from the normal commensal flora were characterized for the phylogenetic type, the virulence factors (VFs) carriage and the Rep-PCR clonal composition.The B2 phylogenetic type was predominant among the urinary isolates (59%), the B2 and D strains among the haematic isolates (32% and 32%).The A phylogenetic type was predominant among the commensal and the respiratory isolates (52% and 58% respectively).The distribution of the B2 type strains among the urinary isolates and of the D type strains among the faecal isolates was suggesting a urinary-origin for the B2 phylogenetic type isolates found in the blood and a direct faecal derivation for the haematic isolates with D phylogenetic type.Twenty-nine VFs were analyzed.The B2 and D type strains carried a higher burden of VFs than the A and B1 phylogenetic type strains (average of VFs/strain = 8 vs 3). Some of the VFs were homogeneously distributed among the phylogenetic types (fimH, iutA, fyuA, traT). The PAI, papGII, ibeA, KpsMTIII were exclusive of B2 and D phylogenetic type strains, while sfa/foc, focG, cnf1, hlyA and rfc were exclusively observed among the B2 type strains.The clustering analysis by Rep-PCR distinguished two groups of strains, the first including 96.77% of B2 and D type strains, while the second encompassing 91,5% of A and B1 type strains

Rapid tests: preliminar identification from blood culture

In the period 1 April to 30 June 2011, we compared the rapid test identification of 250 positive blood cultures with the identification by MALDI-TOF mass spectrometer (Bruker). After Gram staining and an important step in HB&L liquid culture (Alifax), rapid tests were performed according to the morphological characteristics of the sample. Pneumococcus urinary antigen test and tube coagulase test showed a concordance of 100%, the concordance rates for Pyr test and oxidase test were 91% and 89% respectively. Overall, the percentage of agreement of the rapid tests on 250 samples was found to be of 99.2%. The data obtained show that, even with their increased bacterial concentration due to the enrichment step in HB&L liquid culture, it is possible to obtain preliminary identification directly from positive blood culture with simple rapid tests

Direct identification of bacteria in blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: a new methodological approach

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been demonstrated to be a powerful tool for the rapid identification of bacteria from growing colonies. In order to speed up the identification of bacteria, several authors have evaluated the usefulness of this MALDI-TOF MS technology for the direct and quick identification bacteria from positive blood cultures. The results obtained so far have been encouraging but have also shown some limitations, mainly related to the bacterial growth and to the presence of interference substances belonging to the blood cultures. In this paper, we present a new methodological approach that we have developed to overcome these limitations, based mainly on an enrichment of the sample into a growing medium before the extraction process, prior to mass spectrometric analysis. The proposed method shows important advantages for the identification of bacterial strains, yielding an increased identification score, which gives higher confidence in the results. Copyright © 2011 John Wiley & Sons, Ltd

Direct identification from Bact/Alert™ blood culture bottles by MALDI-TOF

Bacterial identification from blood culture using traditional methods needs about 48 hours, since positivization, to be performed. Rapid bacterial identification can result in clinical and economic benefits. To provide rapid pathogen identification for targeted antibiotic treatment, in this study we tested an our previously described homemade method for bacterial identification using MALDI-TOF directly from positive BACTEC blood culture, on positive BacT/ALERT blood culture. A total of 108 bacteria were identified by MALDI-TOF with a positive identification obtained for 98% of Gram negative and 84,3% of Gram positive bacteria.The average of identification score obtained using the protocol described in this study was 2,047 for Gram positive and 2,204 for Gram negative microorganisms. Data here described show that this method is also useful when BacT/ALERT bottles are used and even if these bottles have activated charcoal as inhibitor of antibiotics

Le infezioni catetere vascolare correlate: risultati di tre anni di sorveglianza (2001-2003)

Central venous catheter represents a major source of nosocomial bloodstream infection, which cause considerable excess morbidity.The diagnosis of catheter-related infections relies on the presence of clinical manifestation of infection and the evidence of colonization of the catheter tip by bacteria or fungi. The most frequent pathogens were Gram-positive organisms, mainly coagulase negative staphylococci, followed by Gram-negative and mycetes. During the years 2001-2003 we examined 2079 vascular catheters, of which 896 were positive for bacterial and fungal species. Of these, 675 (75,3%) involved Gram-positive bacterial, 145 (16,2%) Gram-negative and 76 (8,5%) mycetes