Rev Esp Quimioter 2015:28(2):98-100

Phenotypic methods for detection of methicillin-resistant Staphylococcus aureus                                 
 


GERTRUDIS HORNA, LIZETH ASTOCONDOR, JAN JACOBS, CORALITH GARCÍA              

 
Background.  Cefoxitin is a potent inducer of the mecA gene. It is currently as a screening recommended method for presumptive identification of isolates of methicillin resistant Staphylococcus aureus (MRSA). The aim of the study was to compare the sensitivity and specificity of the cefoxitin disc diffusion (30μg) to oxacillin agar screening from detection of the mecA gene by PCR.
Methods. Three hundred thirty-one strains of S. aureus isolated from blood cultures of patients from hospitals in Lima were used in the study. The following tests were performed: oxacillin screening agar (plates were inoculated with 4% NaCl and 6 mg/L of oxacillin), cefoxitin disc diffusion test (30 ug) and PCR to amplify the mecA gene.
Results.  The mecA gene was detected in 165 out of 331 S. aureus isolates. Thus, the frequency of detection of MRSA was 50%. The evaluation of the cefoxitin disc diffusion test showed a 96.3% and 90.9% of sensitivity and specificity, respectively.
Conclusion. Cefoxitin disc diffusion test correlated well with detection of the mecA gene by PCR. Therefore, this test can be an alternative to PCR for detection of MRSA in limited resources settings.

Rev Esp Quimioter 2015:28(2):98-100 [pdf]

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Rev Esp Quimioter 2015:28(Suppl. 1):1-4

Update in Infectious Diseases 2015     

                        
FRANCISCO JAVIER CANDEL, LAURA LÓPEZ GONZÁLEZ, ANA BELÉN GARCÍA-GARCÍA, FLAVIA CHIARELLA, JUAN JOSÉ PICAZO              

Infectious disease remains current worldwide. During the second half of 2014 an outbreak of ebolavirus hit West Africa with implications in the rest of the world. In fact, Spain declared the first imported case of this infection. Multiresistant enterobacteria outbreaks are emerging all around the world in a moment on which WHO draws attention to the limited resources, coining the term “post antibiotic era”. On the other hand, 2014 went down in history as one in which hepatitis C is cured. Are also current HIV epidemiological control or strategies for antiviral and antifungal prophylaxis in immunocompromised hosts.

Rev Esp Quimioter 2015:28(Suppl. 1):1-4 [pdf]

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Rev Esp Quimioter 2015:28(5):242-246

Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry for identifying respiratory bacterial pathogens: a fast and efficient method     

                        
Mª FÁTIMA LÓPEZ-FABAL, JOSÉ LUÍS GÓMEZ-GARCÉS, JOSÉ LUÍS LÓPEZ-HONTANGAS, NURIA SANZ, CARMEN MUÑOZ, MARTA REGODÓN              

Mass spectrometry has become a reference resource for identifying microorganisms in clinical microbiology services. One hundred and fifty one clinical isolates were selected from respiratory specimens routinely identified as Streptococcus pneumoniae (43), Haemophilus influenzae (64) and Moraxella catarrhalis (44). These identifications were compared with other phenotypical methods and mass spectrometry (MALDI-TOF-MS Vitek). Result discrepancies were assessed by 16S rRNA sequencing. Thirty-eight of the 43 strains of S. pneumoniae (86%) were identified as such using phenotypical methods and spectrometry. In 5 cases, MALDI-TOF identified 4 of them as Streptococcus pseudopneumoniae and 1 as S. mitis/oralis. Forty-eight of the 64 strains were identified as H. influenzae (75%) using biochemical identification systems and automated identification systems, whereas MALDI-TOF-MS Vitek identified 51 strains (79%) as such. Conventional methods and spectrometry identified all the 40 strains tested (100%) as M. catarrhalis. All strains with discrepant results were sequenced, and in all cases, the identification obtained by spectrometry was confirmed. The results obtained in this study show that mass spectrometry provides identification of these bacteria faster and in a more reliable way than those based on conventional phenotypical methods.

Rev Esp Quimioter 2015:28(5):242-246 [pdf]

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