Rev Esp Quimioter 2015:28(2):101-108

Genotypic and phenotypic diversity in Enterococcus faecalis: is agar invasion a pathogenicity score?                                 
 


FABIO CAFINI, FERNANDO GÓMEZ-AGUADO, MARÍA TERESA CORCUERA, CARMEN RAMOS, PEDRO BAS, LUIS COLLADO, MARÍA LUISA GÓMEZ-LUS, JOSÉ PRIETO              

 

Objectives. The main objective of the present study is to analyze different genotypic and phenotypic traits related to virulence in Enterococcus faecalis, as well as evaluated the agar invasion phenotype in a collection of isolates with different clinical origins. 
Material and methods. Seventy-nine E. faecalis isolates, with invasive and non-invasive clinical origins, have been used in this work. Presence of cytolysin activator (cylA), gelatinase (gelE), surface protein (esp), aggregation substance (asa1), endocarditis antigen (efaA), and collagen-binding protein (ace) have been analyzed by PCR. Phenotypic characterization included gelatinase activity, haemolysin production, biofilm formation and agar invasion. 
Results. All the isolates tested harboured at least one of the virulence determinants. The 95.5% of isolates from haematologic samples were positive for agar invasion test, significantly higher than isolates from non-invasive diseases. A significant reduction in relative invasion area was observed in three selected agar-invasive strains after 15 serial passages.
Conclusions. It has been observed a significant high prevalence of agar-invasion positive isolates among strains belonged to haematological samples. Agar invasiveness is reduced after adaptation of clinical isolates to laboratory conditions, showing that agar invasion phenotype can be modulate by culture conditions as other virulence factors observed in different bacterial species.

Rev Esp Quimioter 2015:28(2):101-108 [pdf]

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Rev Esp Quimioter 2015:28(Suppl. 1):5-7

Applicability of new diagnostic techniques in microbiology; technological innovation     

                        
RAFAEL CANTÓN, ELENA LOZA, JOSÉ ROMERO              

Different new techniques have been introduced in microbiology laboratories during the last years, including mass spectrometry and next generation sequencing. These techniques, in addition to automation, microfludics, nanotechnology and informatics, have impelled innovation in the prevention and management of patients with infectious diseases. These approaches are relevant for revitalization and consolidation Clinical Microbiology laboratories.

Rev Esp Quimioter 2015:28(Suppl. 1):5-7 [pdf]

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Rev Esp Quimioter 2015:28(5):247-255

A two-hour procedure for determining the susceptibility of enterococci and staphylococci to antibiotics by a colourimetric method     

                        
GABRIEL ALBERTO MARCH-ROSSELLÓ, MARÍA PURIFICACIÓN GUTIÉRREZ-RODRÍGUEZ, MARÍA SIMARRO-GRANDE, ANTONIO ORDUÑA-DOMINGO, MIGUEL ÁNGEL BRATOS-PÉREZA              

Introduction. Rapid determination of the antibiotic susceptibility test in bacteria remains a challenge for Clinical Microbiology laboratories.
Methods. An improvement in the colorimetric antimicrobial susceptibility testing performed with resazurin in enterococci and staphylococci has been carried out. The design of method was performed using two collection strains, which have a known susceptibility. This procedure was then validated against standard commercial methods on 15 strains of staphylococci and 15 strains of enterococci from patients.
Results. The essential agreement between the colorimetric method and commercial methods (E-test, MicroScan and VITEK2) was 100%.
Conclusion. Resazurin allows us to obtain a reliable antibiotic susceptibility test in staphylococci and enterococci in less than two hours.

Rev Esp Quimioter 2015:28(5):247-255 [pdf]

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