Almudena Burillo

Criteria used when initiating antifungal therapy against Candida spp. in the intensive care unit

Invasive candidiasis is a life threatening complication for intensive care unit (ICU) patients. The infection is difficult to recognise so that treatment may be delayed or even not given. Risk factors for candidiasis include the use of antimicrobial agents, central intravascular devices (mainly Hickmann catheters), recurrent gastrointestinal perforations, surgery for acute pancreatitis or splenectomy and renal dysfunction or haemodialysis. Therapy against Candida spp is recommended in ICU patients with endophthalmitis or chorioretinitis possibly caused by Candida spp., in symptomatic patients with risk factors for invasive candidiasis especially if two or more anatomical sites are colonised and for asymptomatic high-risk surgical patients (with recent abdominal surgery or recurrent gastrointestinal perforations or anastomotic leakages). The isolation of Candida from any site poses an increased risk but there are a few microbiological data that might help to establish the predictive value of a particular isolate. These include the site of isolation, the number of culture positive, noncontigous sites, the density of colonisation and the species isolated. Antifungals should be started when Candida spp. are recovered from blood cultures or from usually sterile body fluids, abscesses or wounds in burns patients. They should also be considered in patients with a colonisation index >0.5 or a corrected colonization index >0.4 or when the isolate is identified as Candida tropicalis.

Rhodococcus equi infection in transplant recipients: case report and review of the literature.

BACKGROUND Rhodococcus equi is an opportunistic pathogen that usually causes infection in immunocompromised hosts, mainly human immunodeficiency virus-positive patients, yet solid organ transplant recipients may be affected as well. Infections in this group of patients have not been sufficiently analyzed. METHODS We report an R equi pneumonia in a heart transplant recipient and review another 11 cases. RESULTS Infection appeared a mean of 49 months (range 1-180) after transplantation. Lung was primarily involved in 10 cases (83.3%). The remaining two cases presented with a paravertebral abscess and a purulent pericarditis. Invasive techniques were necessary to reach the diagnosis in nine cases. One patient healed with surgical resection of the lesion; the remaining 11 received antimicrobial agents. Six of them required additional surgical treatment. Three patients died. CONCLUSIONS Clinicians should consider R equi when evaluating a solid organ recipient with an asymptomatic lung nodule. Microbiology laboratories should be alerted in these cases because it could be mistaken for a contaminant diphtheroid and will not respond to the standard empirical therapy.

Gram-Stain Plus MALDI-TOF MS (Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry) for a Rapid Diagnosis of Urinary Tract Infection

Microbiological confirmation of a urinary tract infection (UTI) takes 24–48 h. In the meantime, patients are usually given empirical antibiotics, sometimes inappropriately. We assessed the feasibility of sequentially performing a Gram stain and MALDI-TOF MS mass spectrometry (MS) on urine samples to anticipate clinically useful information. In May-June 2012, we randomly selected 1000 urine samples from patients with suspected UTI. All were Gram stained and those yielding bacteria of a single morphotype were processed for MALDI-TOF MS. Our sequential algorithm was correlated with the standard semiquantitative urine culture result as follows: Match, the information provided was anticipative of culture result; Minor error, the information provided was partially anticipative of culture result; Major error, the information provided was incorrect, potentially leading to inappropriate changes in antimicrobial therapy. A positive culture was obtained in 242/1000 samples. The Gram stain revealed a single morphotype in 207 samples, which were subjected to MALDI-TOF MS. The diagnostic performance of the Gram stain was: sensitivity (Se) 81.3%, specificity (Sp) 93.2%, positive predictive value (PPV) 81.3%, negative predictive value (NPV) 93.2%, positive likelihood ratio (+LR) 11.91, negative likelihood ratio (−LR) 0.20 and accuracy 90.0% while that of MALDI-TOF MS was: Se 79.2%, Sp 73.5, +LR 2.99, −LR 0.28 and accuracy 78.3%. The use of both techniques provided information anticipative of the culture result in 82.7% of cases, information with minor errors in 13.4% and information with major errors in 3.9%. Results were available within 1 h. Our serial algorithm provided information that was consistent or showed minor errors for 96.1% of urine samples from patients with suspected UTI. The clinical impacts of this rapid UTI diagnosis strategy need to be assessed through indicators of adequacy of treatment such as a reduced time to appropriate empirical treatment or earlier withdrawal of unnecessary antibiotics.

Rapid Detection of Staphylococcus aureus in Lower Respiratory Tract Secretions from Patients with Suspected Ventilator-Associated Pneumonia: Evaluation of the Cepheid Xpert MRSA/SA SSTI Assay

ABSTRACT A preclinical evaluation was conducted to evaluate the performance of the Cepheid Xpert assay on 135 lower respiratory tract secretions for detection of methicillin-resistant Staphylococcus aureus and S. aureus. Compared with the quantitative culture, the sensitivity, specificity, and positive and negative predictive values were 99.0%, 72.2%, 90.7%, and 96.3%, respectively.

Advances in the prevention and management of ventilator-associated pneumonia.

Purpose of review Despite copious literature on ventilator-associated pneumonia (VAP), several aspects of this subject remain controversial. We review the current state of the prevention, diagnosis, and treatment of VAP, paying special attention to data reported over the past year. Recent findings The latest recommendations for VAP prevention stress the importance of implementing ventilator bundles and VAP-specific process measures such as hand hygiene in healthcare workers and regular oral care with a chlorhexidine antiseptic in patients. Isolated interventions such as aspirating subglottic secretions or the use of silver-coated endotracheal tubes have also achieved a reduction in the incidence of VAP. Improvement should be confirmed by active surveillance. Summary There is still no consensus as to the best microbiological diagnostic method for VAP, although an early, rapid, and accurate diagnosis should be pursued. Most recent improvements include the direct antibiogram using E-test strips. There is much clinical assessment work pending before biomarkers and molecular techniques become routine practice. The best treatment strategy consists of immediate antimicrobial treatment deescalated later according to clinical progress and culture results. Emphasis is placed on the need for timely short treatment courses to avoid the emergence of resistance.

Mixed bloodstream infections involving bacteria and Candida spp.

OBJECTIVES Polymicrobial bloodstream infection (BSI) is an imprecisely defined entity purportedly associated with a worse outcome than monomicrobial BSI. This study examines trends in BSI episodes caused by bacteria and Candida spp. (mixed-BSI) in a large teaching hospital. METHODS All episodes of BSI from January 2000 to December 2010 were reviewed. Three groups (n = 54 each) of patients were compared: all adults with mixed-BSI from January 2006 to December 2010 (cases) and randomly selected patients with polybacterial BSI (polyB-BSI) (Control 1) or Candida spp. BSI (Candida-BSI) (Control 2) in this same period. RESULTS A total of 139 episodes of mixed-BSI were recorded (0.7% of all BSI, 6.9% of all poly-BSI and 18.0% of all Candida-BSI episodes). The incidence of mixed-BSI was 0.21 cases/1000 admissions, increasing from 0.08 (2000) to 0.34 (2010) cases/1000 admissions (P = 0.007). Mixed-BSI represented 11.8% and 22.9% of all episodes of candidaemia in 2000 and 2010, respectively (P = 0.011). Compared with polyB-BSI, mixed-BSI patients showed fewer malignancies, more frequent nosocomial or intravenous catheter BSI source and less frequent intra-abdominal origin, were more frequently admitted to an intensive care unit (ICU), received more antimicrobials and showed a longer hospital stay and higher mortality. Compared with Candida-BSI, mixed-BSI patients showed more severe underlying diseases, were more frequently admitted to an ICU or oncology-haematology unit, showed a higher APACHE II score, more often progressed to septic shock or multiorgan failure and received more antimicrobials. Mortality was similar. CONCLUSIONS Mixed-BSI is a rare, distinct infection with a worse prognosis than polyB-BSI. We were unable to detect differences in the prognosis of mixed-BSI when compared with Candida-BSI.

Oritavancin: a novel lipoglycopeptide active against Gram-positive pathogens including multiresistant strains

Oritavancin is a lipoglycopeptide antibiotic under investigation for the treatment of serious infections caused by Gram-positive bacteria. Oritavancin has demonstrated rapid dose-dependent bactericidal activity towards vancomycin-susceptible and -resistant enterococci, meticillin-susceptible and -resistant Staphylococcus aureus, vancomycin-intermediate S. aureus (VISA), heteroresistant VISA (hVISA), vancomycin-resistant S. aureus (VRSA) and small-colony variants of S. aureus. It is also active against Clostridium difficile. Upon intravenous administration, oritavancin displays a three-compartment pharmacokinetic model, dose proportionality, a distribution volume of ca. 110 L, a terminal elimination half-life in excess of 2 weeks and it is not metabolised. Its pharmacodynamic properties make it an ideal antibiotic for a once-daily or even single-dose regimen. Oritavancin is currently under review by the US Food and Drug Administration. So far, oritavancin has demonstrated efficacy in two pivotal Phase III trials conducted in patients with complicated skin and skin-structure infections in which oritavancin was compared with vancomycin plus cefalexin. In both trials, the primary endpoint (clinical cure in clinically evaluable patients at first follow-up with a 10% non-inferiority margin) was met, with the advantages of shorter duration of therapy and fewer adverse events. Further results indicating its activity against bacteria growing in biofilms as well as stationary-phase bacteria open the way for its use to treat prosthetic device infections, which is to be investigated in upcoming trials.

Diagnóstico microbiológico de las infecciones de piel y tejidos blandos

Las infecciones de piel y tejidos blandos son uno de los procesos infecciosos mas frecuentes en la practica clinica, y su diagnostico microbiologico constituye una de las tareas de mas compleja valoracion dentro del laboratorio. El diagnostico de infeccion de piel y tejidos blandos es clinico y no microbiologico. El diagnostico microbiologico se reserva para los casos en que se precisa conocer la etiologia de la infeccion, bien porque sean de particular gravedad, se sospechen microorganismos menos frecuentes (como en enfermos inmunodeprimidos), haya habido mala respuesta a tratamientos antimicrobianos previos, o se trate de heridas de larga evolucion que no cicatrizan dentro de un periodo de tiempo razonable. Se describen las indicaciones, la tecnica de obtencion y de procesamiento y los criterios de interpretacion de diferentes tipos de cultivos, tales como los cultivos cuantitativos de biopsias y tejidos, y los cultivos semicuantitativos y cualitativos de todo tipo de muestras. En muestras no invasivas de heridas abiertas, la aplicacion del “indice Q” a la tincion de Gram permite estandarizar la evaluacion de la calidad de la muestra y la interpretacion de la implicacion patogena de los diferentes microorganismos aislados en el cultivo de una manera coste-eficaz. El desarrollo de todos estos aspectos se puede consultar en el procedimiento microbiologico SEIMC numero 22: “Diagnostico microbiologico de las infecciones de piel y tejidos blandos” (2.a ed., 2006) ( www.seimc.org/protocolos/microbiologia ).

Soft Tissue Infections Caused by Actinomyces neuii, a Rare Pathogen

Actinomyces neuii rarely causes disease in humans. First described in 1985 in two patients with postcataract endophthalmitis ([4][1]), A. neuii represents 17% of all clinical Actinomyces isolates ([8][2]), with some 132 cases of infection caused by this microorganism reported to date. The

Susceptibility of 228 Non-fermenting Gram-Negative Rods to Tigecycline and Six Other Antimicrobial Drugs

Abstract The aim of the study was to determine the in vitro activity of tigecycline and 6 other antimicrobial drugs used in clinical practice against 228 clinical isolates of nonfermenting Gram-negative rods (NFGNRs) including Acinetobacter spp. Stenotrophomonas maltophilia, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MICs) were determined according to the recommendations of the Clinical and laboratory Standards institute. For tigecycline, we used the criteria approved by the FDA. Almost 50% of the clinical isolates of Acinetobacter spp. were resistant to piperacillin/tazobactam, ciprofloxacin, gentamicin, and ceftazidime. Strains of this microorganism were more susceptible to imipenem, and even more susceptible to colistin and tigecycline; no strains were resistant to tigecycline. Stenotrophomonas maltophilia showed even greater resistance to the drugs tested. Thus, all strains were resistant to imipenem and a large percentage (82.6%) were resistant to piperacillin/tazobactam. Resistance to the other agents tested was also high, with the exception of tigecycline, with only 3 resistant strains (MIC <8 mg/ml). Tigecycline, on the other hand, was scarcely active against Pseudomonas aeruginosa, which bears efflux pump systems such as MexXY-OprM. Almost 90% of strains were resistant to ciprofloxacin; only 8% were resistant to gentamicin; over half were colistin-intermediate or -resistant, and finally, approximately half of the strains were susceptible to the 3 beta-lactams studied. In conclusion, NFGNRs present variable susceptibility patterns, although they are generally highly resistant to antimicrobial agents including those considered more specific. Tigecycline, which showed good activity against most of the strains examined, broadens the spectrum of drugs available for the treatment of infections caused by these complex microorganisms.