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Background: Identification of monosodium urate (MSU) and calcium pyrophosphate dehydrate (CPPD) crystals in synovial fluid samples is diagnostic of gout and CPPD crystal related arthropathy. Various studies have shown poor consistency in results of crystal analysis. Objective: To determine whether training of the analysts increases the consistency. Methods: An expert rheumatologist gave a course on crystal detection and identification. The four trained observers then blindly and independently examined synovial fluid samples previously classified by the expert which had been obtained from patients with both crystal arthropathies and other non-crystal related inflammatory joint conditions. Results: 194 observations were made on 64 synovial fluid samples: 96 without crystals (49.4%), 55 with CPPD crystal (28.4%), and 43 with MSU crystals (22.2%). For crystal detection (presence or absence of crystals), sensitivity was 95.9% and specificity 86.5%. For identification of MSU crystals, sensitivity was 95.3% and specificity 97.2%. For identification of CPPD crystals, sensitivity was 92.7% and specificity 92.1%. The k index of agreement with the reference standard between the observers was 0.84 for any crystal detection, 0.93 for MSU crystal sample identification, and 0.79 for CPPD crystal sample identification. Conclusions: For trained observers, the detection and identification of crystals in synovial fluid is a consistent procedure.

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Background The aim of this study is to evaluate the risk factors for colonisation by multidrug resistant (MDR) K. pneumoniae in a critical care unit and the relationship between colonisation and the antibiotic pressure exerted by the antimicrobial treatments received by patients. Methods A prospective observational was designed. Patients admitted for more than 48 h to an intensive care unit were included. Samples for surveillance cultures were obtained from all the patients upon admission and once a week. The association between risk factors and colonisation by MDR K. pneumoniae was determined by logistic regression. A Cox regression model was used to evaluate the effect of the use of antimicrobials on the colonisation rate. An ARMIA model was used to investigate the association between the incidence of colonisation by MDR strains and the global consumption of antimicrobials in the unit. Results One thousand seven hundred twenty-five patients were included, from which 308 (17.9%) were positive for MDR K. pneumoniae . In the multivariate analysis, hospitalisation for longer than 7 days together with respiratory infection and administration of any antibiotic was associated with increased MR K. pneumoniae colonisation. Patients who received antibiotics for more than 48 h were colonised earlier than patients who did not receive antibiotic treatment [HR: 2.16 (95%CI:1.55–3.03)]. The ARIMA model found a significant association between the monthly colonisation rate for MR K. pneumoniae and the consumption of cephalosporins and carbapenems in the previous month. Conclusion Individual antibiotic administration and the global antibiotic pressure of cephalosporins and carbapenems are associated to an increased colonisation by MDR K. pneumoniae strains.

Implementing an AS focusing on critical care patients is a long-term cost-effective tool. Implementation costs are amortized by reducing antimicrobial consumption to prevent infection by multidrug-resistant pathogens.