Evaluation of the Vitek-MS™ system in the identification of Candida isolates from bloodstream infections.

BACKGROUND: Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) represents a revolution in the identification of microorganisms of clinical interest. Many studies have confirmed the accuracy and fastness of this tool with routine strains. AIMS: To identify clinical isolates of Candida from patients diagnosed with candidemia. METHODS: Vitek-MS™ system was used with a collection of 298 blood isolates of the genus Candida represented by 9 different species. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA cluster was used as the reference method. RESULTS: The results of Vitek-MS™ were concordant with those obtained with the reference method for 279 (93.62%) isolates (Kappa coefficient (κ)=0.91). Vitek-MS™ misidentified 10 (3.36%) isolates and did not identify 9 (3.02%) isolates. CONCLUSIONS: This study determines the potential of Vitek-MS™ in yeast identification, being a reliable and fast alternative in the clinical laboratory, with an acceptable sensitivity of 82% (IC 95%: 70-90.6%), in comparison with a 100% (IC 95%: 92.9-100%) sensitivity of the conventional methods.

Evaluation of the Vitek-MS(TM) system in the identification of Candida isolates from bloodstream infections / Evaluación del sistema VITEK(R) MS(TM) en la identificación de aislamientos de Candida de pacientes con candidemia

Background: Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) represents a revolution in the identification of microorganisms of clinical interest. Many studies have confirmed the accuracy and fastness of this tool with routine strains. Aims: To identify clinical isolates of Candida from patients diagnosed with candidemia. Methods: Vitek-MS(TM) system was used with a collection of 298 blood isolates of the genus Candida represented by 9 different species. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA cluster was used as the reference method. Results: The results of Vitek-MS(TM) were concordant with those obtained with the reference method for 279 (93.62%) isolates (Kappa coefficient (κ)=0.91). Vitek-MS(TM) misidentified 10 (3.36%) isolates and did not identify 9 (3.02%) isolates. Conclusions: This study determines the potential of Vitek-MS(TM) in yeast identification, being a reliable and fast alternative in the clinical laboratory, with an acceptable sensitivity of 82% (IC 95%: 70-90.6%), in comparison with a 100% (IC 95%: 92.9-100%) sensitivity of the conventional methods

Antecedentes: La espectrometría de absorción de masas mediante láser asistido por una matriz (MALDI-TOF MS) representa una revolución en la identificación de microorganismos de interés clínico. Muchos estudios han confirmado la exactitud y rapidez de esta herramienta con aislamientos de la rutina clínica diaria. Objetivos: Identificar aislamientos clínicos del género Candida procedentes de pacientes con un diagnóstico de candidemia. Métodos: Se utilizó el sistema VITEK(R) MS con un grupo de 298 aislamientos sanguíneos del género Candida, representado por 9 especies diferentes. Se utilizó como método de referencia la secuenciación de la región del espaciador de transcripción interno (ITS, por sus siglas en inglés) del ADN ribosómico. Resultados: Los resultados de VITEK(R) MS coincidieron con aquellos obtenidos por el método de referencia en 279 (93,62%) de los aislamientos (coeficiente Kappa [κ]=0,91), mientras que clasificó erróneamente a 10 (3,36%) aislamientos y no identificó otros 9 (3,02%). Conclusiones: VITEK(R) MS es una alternativa fiable y rápida en la identificación de levaduras en el laboratorio clínico, con una sensibilidad aceptable del 82% (IC 95%:70-90,6%) en comparación con una sensibilidad del 100% (IC 95%:92,9-100%) de los métodos convencionales

Microbiological Diagnosis of Sepsis: Polymerase Chain Reaction System Versus Blood Cultures.

OBJECTIVE: To compare the utility of a multiplex polymerase chain reaction system (SeptiFast) and blood cultures for detecting bacteria and fungi in blood samples from patients with severe sepsis or septic shock. METHODS: In a prospective observational study, whole blood samples for SeptiFast testing and for culture were collected on admission from all patients with severe sepsis or septic shock admitted to the intensive care unit between July 2011 and September 2012. SeptiFast results were compared with blood and other culture results. RESULTS: The probability of at least 1 microorganism being isolated at 6 hours was 13-fold higher with the SeptiFast test than with blood cultures (relative risk, 13.5; 95% CI, 5.05-36.06). Unlike culture results, SeptiFast test results were not associated with previous antibiotic consumption. The median time to the first positive blood culture result was 17 hours; SeptiFast results were available in 6 hours. SeptiFast detected genetic material from potentially multiresistant microorganisms in patients whose blood cultures showed no growth at all. CONCLUSIONS: The SeptiFast test provided quicker microbiological diagnosis and identified significantly more microorganisms than blood cultures did, particularly when samples were collected after antibiotic therapy had started or infections were due to resistant bacteria and yeast.

Methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia in haemodialysis patients.

BACKGROUND: The aim of the study was to determine clinical and microbiological differences between patients with methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia (CRB) undergoing or not undergoing haemodialysis, and to compare outcomes. METHODS: Prospective multicentre study conducted at 21 Spanish hospitals of patients with MRSA bacteraemia diagnosed between June 2008 and December 2009. Patients with MRSA-CRB were selected. Data of patients on haemodialysis (HD-CRB) and those not on haemodialysis (non-HD-CRB) were compared. RESULTS: Among 579 episodes of MRSA bacteraemia, 218 (37.7%) were CRB. Thirty-four (15.6%) were HD-CRB and 184 (84.4%) non-HD-CRB. All HD-CRB patients acquired the infection at dialysis centres, while in 85.3% of the non-HD-CRB group the infection was nosocomial (p < .001). There were no differences in age, gender or severity of bacteraemia (Pitt score); comorbidities (Charlson score ≥ 4) were higher in the HD-CRB group than in the non-HD-CRB group (73.5% vs. 46.2%, p = .003). Although there were no differences in VAN-MIC ≥ 1.5 mg/L according to microdilution, using the E-test a higher rate of VAN-MIC ≥ 1.5 mg/L was observed in HD-CRB than in non-HD-CRB patients (63.3% vs. 44.1%, p = .051). Vancomycin was more frequently administered in the HD-CRB group than in the non-HD-CRB group (82.3% vs. 42.4%, p = <.001) and therefore the appropriate empirical therapy was significantly higher in HD-CRB group (91.2% vs. 73.9%, p = .029). There were no differences with regard to catheter removal (79.4% vs. 84.2%, p = .555, respectively). No significant differences in mortality rate were observed between both groups (Overall mortality: 11.8% vs. 27.2%, p = .081, respectively), but there was a trend towards a higher recurrence rate in HD-CRB group (8.8% vs. 2.2%, p = .076). CONCLUSIONS: In our multicentre study, ambulatory patients in chronic haemodialysis represented a significant proportion of cases of MRSA catheter-related bacteraemia. Although haemodialysis patients with MRSA catheter-related bacteraemia had significantly more comorbidities and higher proportion of strains with reduced vancomycin susceptibility than non-haemodialysis patients, overall mortality between both groups was similar.

Tsukamurella pulmonis bloodstream infection identified by secA1 gene sequencing.

Recurrent bloodstream infections caused by a Gram-positive bacterium affected an immunocompromised child. Tsukamurella pulmonis was the microorganism identified by secA1 gene sequencing. Antibiotic treatment in combination with removal of the subcutaneous port healed the patient.

Risk factors and prognosis of nosocomial bloodstream infections caused by extended-spectrum-beta-lactamase-producing Escherichia coli.

Extended-spectrum-beta-lactamase (ESBL)-producing Escherichia coli (ESBLEC) is an increasing cause of community and nosocomial infections worldwide. However, there is scarce clinical information about nosocomial bloodstream infections (BSIs) caused by these pathogens. We performed a study to investigate the risk factors for and prognosis of nosocomial BSIs due to ESBLEC in 13 Spanish hospitals. Risk factors were assessed by using a case-control-control study; 96 cases (2 to 16% of all nosocomial BSIs due to E. coli in the participating centers) were included; the most frequent ESBL was CTX-M-14 (48% of the isolates). We found CTX-M-15 in 10% of the isolates, which means that this enzyme is emerging as a cause of invasive infections in Spain. By repetitive extragenic palindromic sequence-PCR, most isolates were found to be clonally unrelated. By multivariate analysis, the risk factors for nosocomial BSIs due to ESBLEC were found to be organ transplant (odds ratio [OR]=4.8; 95% confidence interval [CI]=1.4 to 15.7), the previous use of oxyimino-beta-lactams (OR=6.0; 95% CI=3.0 to 11.8), and unknown BSI source (protective; OR=0.4; 95% CI=0.2 to 0.9), and duration of hospital stay (OR=1.02; 95% CI=1.00 to 1.03). The variables independently associated with mortality were a Pitt score of >1 (OR=3.9; 95% CI=1.2 to 12.9), a high-risk source (OR=5.5; 95% CI=1.4 to 21.9), and resistance to more than three antibiotics, apart from penicillins and cephalosporins (OR=6.5; 95% CI=1.4 to 30.0). Inappropriate empirical therapy was not associated with mortality. We conclude that ESBLEC is an important cause of nosocomial BSIs. The previous use of oxyimino-beta-lactams was the only modifiable risk factor found. Resistance to drugs other than penicillins and cephalosporins was associated with increased mortality.

Bacteriemia y sepsis por Leuconostoc mesenteroides / Bacteremia and sepsis due to Leuconostoc mesenteroides

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High concentrations of manganese in Mueller-Hinton agar increase MICs of tigecycline determined by Etest.

MICs of tigecycline determined by Etest were 4 to 12 times (three ATCC strains) and 2 to 8 times (50 clinical isolates) higher in Mueller-Hinton agar from Merck than in Mueller-Hinton agar from either Oxoid or Difco. This was related to a much higher concentration of manganese in the medium from Merck.