Evaluation of antimicrobial susceptibility testing of Nocardia spp. isolates by broth microdilution with resazurin and spectrophotometry.

BACKGROUND: Nocardia species are ubiquitous in natural environments and can cause nocardiosis. In the present study, the use of Resazurin salt and Spectrophotometry were proposed as alternative methods to reduce subjectivity in the interpretation of susceptibility results to antimicrobials by the broth microdilution method for Nocardia spp. RESULTS: The susceptibility of Nocardia spp. isolates to Amikacin, Ciprofloxacin, Minocycline and Trimethoprim-Sulfamethoxazole was evaluated by Minimum Inhibitory Concentration (MIC) determinations by the broth microdilution method. To verify cellular growth, the colour-changing dye Resazurin was applied, the Optical Densities were measured on a spectrophotometer, and both were compared to Clinical and Laboratory Standards Institute (CLSI) Gold Standard method (visual MIC determination). Percentages of essential and categorical agreements and interpretative categorical errors were calculated within each method (intra-reading) and between them (inter-reading). The Gold Standard visual reading demonstrated 100% of essential and categorical intra-reading agreements for Amikacin, and there was no error when compared with the alternative methods. For Ciprofloxacin, the comparison between the Gold Standard and the Spectrophotometric reading showed 91.5% of essential agreement. In the categorical intra-reading analysis for Minocycline, there were 88.1 and 91.7% in the Gold Standard and in the Spectrophotometric readings, respectively, and 86.4% of concordance between them. High rates of categorical agreement were also observed on the Trimethoprim-Sulfamethoxazole analyses, with 93.7% for the Gold Standard, 84.9% for the Resazurin readings, and 80.5% between them. CONCLUSIONS: The alternative methods with Resazurin and Spectrophotometric readings showed high agreement rates with the Gold Standard.

Relationship of glomerular filtration rate and serum CK activity after resistance exercise in women.

The aim of study was to assess the correlation between the changes in serum CK activity after a resistance exercise and renal function measured by glomerular filtration rate (eGFR). Twenty-nine trained women (32 ± 10 years; 157 ± 4 cm; 58.8 ± 6.4 kg) performed a resistance exercise session with 17 exercises with 3 × 12 repetitions in a circuit training fashion. Subjects provided blood samples prior to exercise session (PRE), and at 24, 48, and 72 h following exercise session for creatine kinase (CK) and creatinine. 24-Urine samples were collected before and 72 h after exercises. eGFR was obtained by the three most recommended methods (MDRD; MCQE; Cockcroft-Gault). After the exercise session, serum CK activity increase up 1.68 times (P < 0.01). Serum creatinine increased 25.5% (P = 0.0000) while urinary creatinine decreased on average 6.4% (P = 0.0422). eGFR decreased in all formulas: MDRD by 21.5%, MCQE by 14.2%, and C-G by 17% (all with P < 0.01). Ccr also decreased (-22.9%, P < 0.01). The index of correlation was significant for MDRD (r = -0.924; P < 0.01), C-G (r = -0.884; P < 0.01), and MQCE (r = -0.644; P < 0.05). In conclusion, we observed a significant negative correlation between CK activity and the eGFR indices of renal function.