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The sensitivity of periprosthetic tissue culture is inadequate for the diagnosis of prosthetic joint infection (PJI). We investigated and compared the values of sonication fluid culture and periprosthetic tissue culture for diagnosing PJI.Included were patients whose joint prosthesis had been removed for any reason. The resulting sonication fluid and periprosthetic tissues were cultured for 14 days.Of 231 explanted prostheses, aseptic failure was diagnosed in 162 cases (70%) and PJI in 69 (30%). In PJI cases, sonication fluid culture detected 62 microorganisms and periprosthetic tissue culture detected 45. Tissue and sonication fluid cultures showed sensitivities of 61% and 81%, respectively (p0.01), with specificity of 100% and 99%, respectively. On day 1, tissue and sonication fluid cultures were positive in 13% and 28% (p = 0.013) of PJI cases respectively, and on day 2, in 26% and 48% (p = 0.002) of cases. Four anaerobes grew in sonication fluid culture after 7-13 days incubation, whereas tissue culture missed 3 of these. Prolonged incubation of sonication fluid did not detect any organisms in the cases of aseptic failure.Sonication fluid culture provides a more rapid diagnosis and detects about 30% more pathogens, although anaerobic organisms require up to 2 weeks of incubation.

The outcome of revision surgery depends on accurate determination of the cause of prosthesis failure because treatment differs profoundly among aseptic loosening, mechanical failure, and prosthetic joint infections (PJI).We sought to determine (1) the predictive role of the interval from primary to revision surgery in determining the reason for prosthesis failure of a hip, knee, shoulder, or elbow arthroplasty, and (2) whether positive cultures during revision surgery for aseptic loosening were associated with shorter event-free survival of the prosthesis.All patients undergoing revision surgery between July 2010 and January 2012 were included in a prospective cohort of 112 patients, and were classified as having had failure from aseptic loosening (56%), mechanical failure (15%), or PJI (29%). To make the diagnosis of PJI, at surgery we used a standardized enhanced diagnostic approach in all patients including sampling of five periprosthetic tissue specimens, sonication of removed prosthetic components, prolonged incubation of aerobic and anaerobic cultures, and multiplex PCR of sonication fluid in aseptic loosening cases. Kaplan-Meier survival and Cox proportional hazards regression analysis were performed.The median time from primary to revision surgery was (p0.001) longer for patients with aseptic loosening (7.8 years) than for patients with mechanical failure (1.6 years) or PJI (2 years). No difference in the time to revision was observed for patients with aseptic loosening with positive or negative microbiological cultures (p = 0.594). Propionibacterium acnes was cultured below the established microbiological criteria for positivity in 12 (19%) procedures that had been presumed to have been revisions for aseptic loosening.PJI should be considered in all revisions performed within 2 years of implantation even in the absence of clinical or laboratory findings suggestive for infection. However, the growth of low-virulence microorganisms below the cut-off in revisions for apparent aseptic loosening is not associated with early prosthesis failure.

Biofilm removal efficacy of vortexing alone was compared with the standard vortexing-sonication procedure. Among 135 removed prostheses, 35 were diagnosed with infection and 100 with aseptic failure. At a cutoff of ≥50 CFU/ml, sonication was more sensitive than vortexing (60% versus 40%, P = 0.151), while the specificity was 99% for both methods.

The purpose of this study was to compare the diagnostic accuracy for the detection of infection between the culture of fluid obtained by sonication (SFC) and the culture of peri-implant tissues (PITC) in patients with early and delayed implant failure, and those with unsuspected and suspected septic failure. It was hypothesised that SFC increases the diagnostic accuracy for infection in delayed, but not early, implant failure, and in unsuspected septic failure. The diagnostic accuracy for infection of all consecutive implants (hardware or prostheses) that were removed for failure was compared between SFC and PITC. This prospective study included 317 patients with a mean age of 62.7 years (9 to 97). The sensitivity for detection of infection using SFC was higher than using PITC in an overall comparison (89.9% versus 67%, respectively; p < 0.001), in unsuspected septic failure (100% versus 48.5%, respectively; p < 0.001), and in delayed implant failure (88% versus 58%, respectively; p < 0.001). PITC sensitivity dropped significantly in unsuspected compared with suspected septic failure (p = 0.007), and in delayed compared with early failure (p = 0.013). There were no differences in specificity. Sonication is mainly recommended when there is implant failure with no clear signs of infection and in patients with delayed implant failure. In early failure, SFC is not superior to PITC for the diagnosis of infection and, therefore, is not recommended as a routine diagnostic test in these patients. Cite this article: Bone Joint J 2013;95-B:244–9.

To analyze the characteristics of infection, adequacy of empirical treatment and outcome of patients with community-onset healthcare-associated (HCA) urinary tract infections (UTI) and compare them with hospital (HA) and community-acquired (CA) UTI.Prospective observational cohort study performed at a university 600-bed hospital between July 2009 and February 2010. Patients with UTI requiring hospital admission were included. Epidemiological, clinical and outcome data were recorded.251 patients were included. Patients with community-onset HCA UTI were older, had more co-morbidities and had received previous antimicrobial treatment more frequently than CA UTI (p = 0.02, p = 0.01 and p0.01). ESBL-Escherichia coli and Pseudomonas aeruginosa infections were more frequent in HCA than in CA UTI (p = 0.03 and p0.01). Inadequate empirical treatment was not significantly different between community-onset HCA and CA. Factors related to mortality were P. aeruginosa infection (OR 6.51; 95%CI: 1.01-41.73), diabetes mellitus (OR 22.66; 95%CI: 3.61-142.21), solid neoplasia (OR 22.48; 95%CI: 3.38-149.49) and age (OR 1.15; 95%CI 1.03-1.28).Epidemiological, clinical and microbiological features suggest that community-onset HCA UTI is different from CA and similar to HA UTI. However, in our series inadequate empirical antimicrobial therapy and mortality were not significantly higher in community-onset HCA than in CA UTI.

The aim of this study was to evaluate the reliability of the VersaTREK system for Mycobacterium tuberculosis drug susceptibility testing compared with results obtained with the Bactec MGIT 960 system. A total of 67 strains were evaluated. Overall agreement was at 98.5%. Kappa indexes were 1.0 for isoniazid, rifampin, and ethambutol, 0.937 for pyrazinamide, and 0.907 for streptomycin. The VersaTREK system is validated for M. tuberculosis drug susceptibility testing.

Objectives To determine whether the incidence of bacteremia after transrectal ultrasound-guided prostate biopsy (TRUSGPB) significantly diminishes with the setting up of a new preventive protocol. This protocol was set up after detecting an augmented incidence of bacteremia after TRUSGPB with a high prevalence of antibiotic-resistant microorganisms. Methods Retrospective descriptive and prospective intervention study performed at a University Hospital. Participants: Patients undergoing TRUSGPB under the old preventive protocol (January 2006-February 2007), that is, amoxicillin-clavulanate 500 mg tid the day before, the day of the procedure, and 1 day after the procedure, and after setting up a new protocol (March 2007-April 2008), that is, 2 g cefoxitin 1 hour before the procedure and ciprofloxacin 750 mg p.o. bid the day before, the day of the procedure, and 3 days after the procedure; dipstick urinalysis was performed before the procedure, and patients with positive results were not biopsied. Results Incidence of bacteremia with old and new protocols: 9 of 204 procedures (4.4%) vs 2 of 207 (0.9%), (P = .03). Four isolates (44.4%) under the old protocol produced extended-spectrum beta-lactamase (ESBL). With the new protocol, 2 (0.9%) cases of non-ESBL Escherichia coli bacteremia were observed. Sixty-five (23.8%) cases were not biopsied because of positive result of dipstick urinalysis, lack of antibiotic prophylaxis adherence, or altered coagulation parameters. Conclusions Antibiotic prophylaxis for TRUSGPB should take into account local resistance patterns. Cefoxitin could be used as prophylaxis in centers with high prevalence of ESBL enterobacteriaceae. Before TRUSGPB, excluding patients with positive results of dipstick urinalysis is an advisable practice.

To compare clinical and microbiological characteristics, treatment and outcomes of MRSA bacteraemia among elderly and younger patients.Prospective study conducted at 21 Spanish hospitals including patients with MRSA bacteraemia diagnosed between June/2008 and December/2009. Episodes diagnosed in patients aged 75 or more years old (≥75) were compared with the rest of them (75).Out of 579 episodes of MRSA bacteraemia, 231 (39.9%) occurred in patients ≥75. Comorbidity was significantly higher in older patients (Charlson score ≥4: 52.8 vs. 44%; p = .037) as was the severity of the underlying disease (McCabe ≥1: 61.9 vs. 43.4%; p.001). In this group the acquisition was more frequently health-care related (43.3 vs. 33.9%, p = .023), mostly from long-term care centers (12.1 vs. 3.7%, p.001). An unknown focus was more frequent among ≥75 (19.9 vs. 13.8%; p = .050) while severity at presentation was similar between groups (Pitt score ≥3: 31.2 vs. 27.6%; p = .352). The prevalence of vancomycin resistant isolates was similar between groups, as was the appropriateness of empirical antibiotic therapy. Early (EM) and overall mortality (OM) were significantly more frequent in the ≥75 group (EM: 12.1 vs. 6%; p = .010 OM: 42.9 vs. 23%; p.001). In multivariate analysis age ≥75 was an independent risk factor for overall mortality (aOR: 2.47, CI: 1.63-3.74; p.001).MRSA bacteraemia was frequent in patients aged ≥75 of our cohort. This group had higher comorbidity rates and the source of infection was more likely to be unknown. Although no differences were seen in severity or adequacy of empiric therapy, elderly patients showed a higher overall mortality.

Sonication improved the diagnosis of orthopedic implant-associated infections (OIAI). We investigated the diagnostic performance of sonication fluid inoculated into blood culture bottles in comparison with that of intraoperative tissue and sonication fluid cultures. Consecutive patients with removed orthopedic hardware were prospectively included and classified as having OIAI or aseptic failure (AF) according to standardized criteria. The diagnostic procedure included the collection of five intraoperative tissue cultures and sonication of the removed device, followed by conventional culture of the sonication fluid. Cultures were incubated for 7 days (aerobic) or 14 days (anaerobic). In addition, 10 ml of sonication fluid was inoculated into each aerobic and anaerobic BacT/Alert FAN blood culture bottle and incubated in the automated blood culture system for 5 days. Of 75 included patients, 39 had OIAI and 36 AF. The sensitivity of sonication fluid inoculated into blood culture bottles (100%) was higher than that of conventional sonication fluid (87%; P = 0.05) or intraoperative tissue cultures (59%; P < 0.01). Previous antibiotic therapy reduced the culture sensitivity of conventional sonication fluid to 77% and that of intraoperative tissue to 55%, while it remained 100% for blood culture-inoculated sonication fluid. The time to positivity was shorter in blood culture-inoculated sonication fluid, with detection of 72% of microorganisms after 1 day of incubation, than for intraoperative tissue and conventional sonication fluid cultures, with detection of 18% and 28% of microorganisms, respectively. In conclusion, compared to conventional sonication fluid and intraoperative tissue cultures, sonication fluid inoculated into blood culture bottles improved the diagnosis of OIAI and considerably reduced the time to culture positivity.

An unexplained resurgence of Group A streptococci (GAS) infections has been observed since the mid-1980s in the United States and Europe, particularly among intravenous drug users (IDUs). Several risk factors have been identified. Mutations in the capsule synthesis regulator genes (csrRS) have been associated with an increase in virulence. From January 1998 to December 2003, we conducted a prospective and retrospective descriptive analysis of invasive GAS soft-tissue infections in IDUs in Barcelona, Spain. Clinical features were collected, and we conducted a surveillance study to identify risk factors associated with GAS soft-tissue infections. We analyzed chromosomal DNA by low cleavage restriction enzymes and used pulsed-field gel electrophoresis (PFGE) and variable gene sequence typing (VGST) of the emm gene to disclose the epidemiologic relationship between the strains. We analyzed the influence of clonality (M-type) and mutations in csrRS genes of these strains on clinical features. We identified 44 cases, all of which were grouped in 3 clusters: fall 2000, fall 2002, and fall 2003. Cellulitis with or without abscesses (75%) and fever (90.9%) were the most common clinical manifestations. Distant septic complications were infrequent (18.2%). Although all patients had severe infections (mainly bacteremic needle abscesses), their outcome with antibiotic therapy, usually beta-lactam, was successful in all cases. However, surgery was needed in 40.9% of patients. Through the surveillance study we found that infected patients had a higher number of drug injections per day (odds ratio [OR], 18.84; 95% confidence interval [CI], 4.83-79.4; p

We aimed to assess the incidence, demographic data, clinical features, and outcome of peritoneal infections due to Listeria monocytogenes in individuals with cirrhosis.During a 10-yr study period, 153 cases of invasive listeriosis were recorded in a prospective population-based surveillance project carried out in Barcelona, Spain.Thirteen cases were of spontaneous bacterial peritonitis by L. monocytogenes. Ages of the patients ranged between 29 and 85 yr. In addition to cirrhosis, underlying conditions included diabetes mellitus in four and malignancy in three. Bacteremia was present in six cases (46%). Only one patient with bacteremia developed meningitis. Analysis of the peritoneal fluid showed a mean (SD) protein content of 21.5 (9.6) g/L and leukocyte count of 7,273 (9,171) cells/ml. L. monocytogenes serotype 4b was the serogroup predominantly isolated (61%). The mortality rate was 30.7%. Eight patients received empirical antibiotic treatment with cephalosporins.In geographical areas with a high incidence of listeriosis, L. monocytogenes should be suspected as a causative pathogen of spontaneous bacterial peritonitis in cirrhosis. Early adjustment of antibiotic therapy is essential to reduce mortality.

Fundamento El objetivo fue conocer, mediante un estudio multicentrico y con la colaboracion de clinicos, microbiologos y epidemiologos, el nivel de resistencias de Mycobacterium tuberculosis en el area de Barcelona y su relacion con datos clinicos de los pacientes para establecer posibles grupos de riesgo. Pacientes y metodo Se incluyeron las cepas de M. tuberculosis aisladas de los pacientes diagnosticados bacteriologicamente desde octubre de 1995 a septiembre de 1997, revisandose su historial clinico. Se estudio la resistencia a isoniacida, rifampicina, estreptomicina, etambutol y pirazinamida mediante el sistema Bactec 460. Los factores asociados a resistencia se analizaron mediante regresion logistica. Resultados El total de pacientes fue de 1.749 (1.535 iniciales y 214 tratados anteriormente). La resistencia primaria fue 5,7% (isoniacida, 3,8%; rifampicina, 1,0%, estreptomicina, 2,1%, etambutol, 0,3% y pirazinamida, 1,0%). La resistencia adquirida alcanzo el 20,5% (isoniacidas, 17,3%, rifampi-cina, 9,8%, etambutol, 1,9%, estreptomicina, 4,7% y pirazinamida, 6,5%). La multirresistencia primaria fue 0,9%, y la adquirida 9,3%. Las resistencias primarias totales, a isoniacida y a pirazinamida se asociaron con inmigracion y se objetivaron algunas diferencias entre laboratorios atribuibles a diferencias de poblacion. Las resistencias adquiridas totales y a isoniacida se asociaron a mas de 60 anos y al sexo femenino. Conclusiones El bajo nivel de resistencias primarias a isoniacida permite tratar los casos iniciales con 3 farmacos, salvo en determinados grupos de inmigrantes. Se recomienda realizar pruebas de sensibilidad en todas las cepas aisladas y realizar estudios de farmacorresistencia en tuberculosis basados en trabajos coordinados para evitar sesgos de poblacion.

Fundamento y objetivo Los pacientes con bacteriemia suelen requerir ingreso hospitalario, aunque en ocasiones se les remite a su domicilio por diagnostico inapropiado o rapida mejoria. En el presente estudio se describen la evolucion y las intervenciones realizadas en los pacientes con bacteriemia comunitaria remitidos a domicilio. Pacientes y metodo Estudio prospectivo realizado en un hospital de 450 camas desde marzo de 2000 hasta diciembre de 2003. El centro dispone de un equipo que controla todas las bacteriemias. Se identifico a los pacientes enviados a su domicilio desde urgencias y que recibieron tratamiento antimicrobiano inapropiado. Resultados Se diagnostico a 1.172 pacientes con bacteriemia verdadera, de los que 247 (21,1%) fueron remitidos a su domicilio. En 50 casos (20,2%) se considero necesario revaluar al paciente: 36 por tratamiento antibiotico inapropiado, 12 sin tratamiento antibiotico y 2 por falta de informacion. En 34 pacientes (64%) se instauro o modifico el tratamiento antimicrobiano y 10 (20%) requirieron ingreso hospitalario. Excluyendo a los 66 pacientes que fallecieron en las primeras 48 h, la mortalidad bruta de los pacientes remitidos a domicilio fue inferior (4%) a la de los pacientes ingresados (11,9%). Conclusiones Una quinta parte de las bacteriemias comunitarias fueron tratadas de forma ambulatoria. Con frecuencia el tratamiento antibiotico fue inapropiado. Es necesario garantizar un control adecuado de estos pacientes.

Urinary tract infections (UTI) include a wide range of clinical entities. Starting from this situation, have been differentiated each of the UTI depending on location, age and sex, among other factors. Therefore, UTI have been classified and studied as follows: UTI in women, in men, in elderly people, in catheterized patients and in children. The different pharmacotherapeutic alternatives have been assessed and the classic agents compared with the most recent molecules.

Summary Objective Cultures have limited sensitivity in the diagnosis of prosthetic joint infection (PJI), especially in low-grade infections. We assessed the value of multiplex PCR in differentiating PJI from aseptic failure (AF). Methods Included were patients in whom the joint prosthesis was removed and submitted for sonication. The resulting sonication fluid was cultured and investigated by multiplex PCR, and compared with periprosthetic tissue culture. Results Among 86 explanted prostheses (56 knee, 25 hip, 3 elbow and 2 shoulder prostheses), AF was diagnosed in 62 cases (72%) and PJI in 24 cases (28%). PJI was more common detected by multiplex PCR ( n =23, 96%) than by periprosthetic tissue ( n =17, 71%, p =0.031) or sonication fluid culture ( n =16, 67%, p =0.016). Among 12 patients with PJI who previously received antibiotics, periprosthetic tissue cultures were positive in 8 cases (67%), sonication fluid cultures in 6 cases (50%) and multiplex PCR in 11 cases (92%). In AF cases, periprosthetic tissue grew organisms in 11% and sonication fluid in 10%, whereas multiplex PCR detected no organisms. Conclusions Multiplex PCR of sonication fluid demonstrated high sensitivity (96%) and specificity (100%) for diagnosing PJI, providing good discriminative power towards AF, especially in patients previously receiving antibiotics.

The authors report a case of an inguinal bubo in a young man caused by an anaerobe, Prevotella bivia, which was acquired during oral sexual intercourse. As far as the authors know, this is the first reported case of a sexually transmitted infection by Prevotella. Prevotella spp. inhabit the oral cavity and are highly prevalent in bacterial vaginosis, a polymicrobial syndrome resulting from replacement of the normal vaginal Lactobacillus spp. flora by high concentrations of anaerobic microorganisms such as Prevotella spp., Mobiluncus spp., Gardnerella vaginalis and other uncultivated anaerobes.

Patients with infected arthroplasties are normally treated with a two-stage exchange procedure using polymethylmethacrylate bone cement spacers impregnated with antibiotics. However, spacers may act as a foreign body to which micro-organisms may adhere and grow. In this study it was hypothesised that subclinical infection may be diagnosed with sonication of the surface biofilm of the spacer. The aims were to assess the presence of subclinical infection through sonication of the spacer at the time of a second-stage procedure, and to determine the relationship between subclinical infection and the clinical outcome. Of 55 patients studied, 11 (20%) were diagnosed with subclinical infection. At a mean follow-up of 12 months (interquartile range 6 to 18), clinical failure was found in 18 (32.7%) patients. Of the patients previously diagnosed with subclinical infection, 63% (7 of 11) had failed compared with 25% (11 of 44) of those without subclinical infection (odds ratio 5.25, 95% confidence interval 1.29 to 21.4, p = 0.021). Sonication of the biofilm of the surface of the spacer is useful in order to exclude subclinical infection and therefore contributes to improving the outcome after two-stage procedures.

The purpose of this investigation was to compare the risk factors, clinical features and outcomes in cancer patients with bacteraemia caused by vancomycin-susceptible Enterococcus faecalis and E. faecium. A retrospective, observational 7-year study was carried out in a 450-bed, acute-care university-affiliated hospital. We performed univariate comparisons between the two groups and then multivariate analysis to identify patient risk factors for E. faecium isolation. Seventy-three patients were included in the analysis: 54 (74.0%) with bacteraemia caused by E. faecalis and 19 (26.0%) by E. faecium. The Simplified Acute Physiological Score (SAPS) value was significantly greater in E. faecium isolates (40.7 vs. 35.2; p = 0.009). Diabetes mellitus was more frequently diagnosed in patients with E. faecium bacteraemia (52.6% vs. 24.1%; p = 0.021). Prior penicillin exposure was more frequent in patients with E. faecium bacteraemia (68.4% vs. 29.6%; p = 0.003). There was a trend toward higher mortality in E. faecium bacteraemia patients (47.4% vs. 25.9%; p = 0.084). Independent patient risk factors for E. faecium isolation were prior penicillin exposure (odds ratio [OR], 6.479; p = 0.003) and SAPS > 34 (OR, 6.896; p = 0.009). When compared to E. faecalis bacteraemia, E. faecium bacteraemia in cancer patients is independently associated with more severe illness and prior use of penicillins; therefore, empiric treatment which would cover E. faecium should be considered in cancer patients suspected of having bacteraemia.

Multidrug-resistant strains of Pseudomonas aeruginosa(MDRPA) have been increasing in some hospitals [1] andmay become a public health problem [2].The emergence of MDRPA has been related to exposureto antibiotics against P. aeruginosa [3, 4]. Most of thesestudies have focussed on particular environments such asthe intensive care unit (ICU) [5] or particular antibioticresistances, mainly quinolone-resistant P. aeruginosa andcarbapenem-resistant P. aeruginosa or specific infectionsites such ventilator-associated pneumonia or bacteraemia[6, 7]. Most studies have used case–control methodology orhave investigated outbreaks, and the case–control studieshave usually compared susceptibility to resistant micro-organisms. This methodology may overestimate the associ-ation between the resistance-defining antibiotic or may befalsely implicated as a potential risk factor for theacquisition of this pattern of susceptibility [8, 9].The aim of this study was to assess the factors related toMDRPA acquisition, especially previous antibiotic expo-sure, using a double case–control methodology [10],analysing all types of infections and all hospital wardsduring a long period of follow-up.We conducted a double case–control epidemiologicalstudy, exploring the risk factors (host characteristics,invasive procedures and, especially, previous antibioticexposure) associated with the acquisition of MDRPA inhospitalised patients from 1 January 2001 to 31 December2006 in a University Hospital with 450 beds. P. aeruginosawas isolated and identified by the microbiology laboratoryby means of routine techniques. The susceptibility of

During a 2-year period (2003–2004), tuberculosis (TB) transmission in Barcelona and the factors related to transmission among the Spanish- and foreign-born populations were studied by molecular epidemiology. Data were obtained from TB cases and Conventional Contact Tracing registries and genotyping was performed using restriction fragment length polymorphism (RFLP)-IS6110 and MIRU12 as a secondary typing method. Of the 892 TB cases reported, 583 (65.3%) corresponded to Spanish-born and 309 (34.6%) to foreign-born. Six hundred and eighty-seven cases (77%) were confirmed by culture. RFLP typing of 463/687 (67.4%) isolates was performed, revealing 280 (60.5%) unique and 183 (39.5%) shared patterns, which were grouped into 65 clusters. Spanish-born individuals were significantly more clustered than foreign-born individuals (44.6% vs. 28.8%; p 0.016). Clustering in foreign-born individuals was associated with HIV (p 0.051, odds ratio = 3.1, 95% confidence interval 1–10.9) and alcohol abuse (p 0.022), whereas, in the Spanish-born individuals, clustering was associated with age in the range 21–50 years, (p 0.024). Of the total clusters, 36/65 (55.3%) included only Spanish-born patients, whereas 22/65 (33.8%) included individuals from both populations. In mixed clusters, the index case was Spanish-born in 53% and foreign-born in 47%. Among the foreign-born, 2.8% were ill on arrival, 30% developed TB within the first year and 50.3% developed TB within the first 2 years; 58.3% were from South America. In conclusion, half of the foreign-born TB patients developed the disease during the first 2 years after arrival, which, in most cases, was the result of endogenous reactivation. Recent TB transmission among Spanish-born and foreign-born populations, as well as bidirectional transmission between communities, contributed significantly to the burden of TB in Barcelona, suggesting the need to improve Public Health interventions in both populations.

In this multicenter study, the reliability of two nonradiometric, fully automated systems, the MB/BacT and BACTEC MGIT 960 systems, for testing the susceptibilities of 82 Mycobacterium tuberculosis strains to isoniazid, rifampin, ethambutol, and streptomycin was evaluated in comparison with the radiometric BACTEC 460TB system. The arbitration of discrepant results was done by the reanalysis of the strain, the determination of the MIC, and the molecular characterization of some resistance determinants. The overall level of agreement with BACTEC 460TB results was 96% with the MB/BacT test and 97.2% with the BACTEC MGIT 960 system. With both methods, the level of agreement with BACTEC 460TB results was 96.3% for isoniazid, 98.8% for rifampin, and 98.8% for ethambutol. The level of agreement for streptomycin was 90.2% with MB/BacT and 97.5% with BACTEC MGIT 960. Overall, there were 11 very major errors and 2 major errors with the MB/BacT method and 5 very major errors and 2 major errors with the BACTEC MGIT 960 system. In general, the MB/BacT and BACTEC MGIT 960 systems showed good performance for susceptibility testing with first-line antituberculosis drugs.

We evaluated the effectiveness and safety of rifampicin addition to clarithromycin in the treatment of Legionnaires' disease. An observational cohort study was conducted on patients assigned to a Legionnaires' disease outbreak. Of 32 patients with confirmed Legionella pneumonia, 11 received clarithromycin monotherapy and 21 received combination therapy of clarithromycin with rifampicin. Both groups had similar baseline characteristics and all patients were cured. Patients who received rifampicin had a 50% longer length of stay (P=0.035) and a trend towards higher bilirubin levels (P=0.053). Length of stay was directly correlated with the duration of rifampicin treatment (P=0.001). Combination therapy of clarithromycin and rifampicin had no additional benefit compared with clarithromycin monotherapy and could prolong the length of stay owing to possible negative drug interactions that could also affect other antibiotics.

9033 Background: The rapid microbiologic diagnosis in the course of fever of unknown origin plays an important role for the appropriate treatment in neutropenic patients. Blood culture helps identi...

Background We aimed to assess the hospital economic costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition. Methods A retrospective study of all hospital admissions between January 1, 2005, and December 31, 2006 was carried out in a 420-bed, urban, tertiary-care teaching hospital in Barcelona (Spain). All patients with a first positive clinical culture for P. aeruginosa more than 48 h after admission were included. Patient and hospitalization characteristics were collected from hospital and microbiology laboratory computerized records. According to antibiotic susceptibility, isolates were classified as non-resistant, resistant and multi-drug resistant. Cost estimation was based on a full-costing cost accounting system and on the criteria of clinical Activity-Based Costing methods. Multivariate analyses were performed using generalized linear models of log-transformed costs. Results Cost estimations were available for 402 nosocomial incident P. aeruginosa positive cultures. Their distribution by antibiotic susceptibility pattern was 37.1% non-resistant, 29.6% resistant and 33.3% multi-drug resistant. The total mean economic cost per admission of patients with multi-drug resistant P. aeruginosa strains was higher than that for non-resistant strains (15,265 vs. 4,933 Euros). In multivariate analysis, resistant and multi-drug resistant strains were independently predictive of an increased hospital total cost in compared with non-resistant strains (the incremental increase in total hospital cost was more than 1.37-fold and 1.77-fold that for non-resistant strains, respectively). Conclusions P. aeruginosa multi-drug resistance independently predicted higher hospital costs with a more than 70% increase per admission compared with non-resistant strains. Prevention of the nosocomial emergence and spread of antimicrobial resistant microorganisms is essential to limit the strong economic impact.