Are Commercial Systems Used for the Identification of Yeasts Enough Alone?: A Case Report

Infections developing due to Trichosporon species especially in immunosuppressed patients have started to increase also in our country as well as in the world. Some difficulties have been encountered in identification and treatment of Trichosporon spp. which are relatively more resistant to antifungal treatment. Accurate and rapid identification of yeast species is very important to ensure determination of the appropriate antifungal agent in treating these infections. Due to long time span and intense effort required, determination using conventional methods has recently been replaced by common use of commercial systems allowing rapid identification. However, the commercial systems used to determine yeasts are reported to have higher correct identification rates for frequently isolated species, whereas lower rates for rarer species. In this report, we aimed to address that the commercial systems are enough alone for identification by evaluating a case of urinary tract infection with a positive urine culture yielding yeasts. A urine culture revealed dry, wrinkled, waxy, pink, yeast-like colonies on blood agar and eosin-methylene blue agar after a 24-hour incubation. These colonies were identified as Cryptococcus sp. using VITEK (R) 2 (bioMerieux, Marcy l'Etoile, France) system. On the other hand, this isolate had been demonstrated as Trichosporon asahii by microscopic and macroscopic appearance, carbohydrate assimilation test results and urease positivity. Additionally, antifungal susceptibility of isolate was determined using microdilution (amphotericin B, voriconazole, fluconazole) and Etest (R) (AB Biodisk, Solna, Sweden) methods (caspofungin, anidulafungin) according to Clinical Laboratory Standards Institute M27-A3 standard. In conclusion, this case report demonstrated that there is a need for confirmation of results with conventional methods for determination of rare species such as Trichosporon spp. identified with commercial systems based on biochemical properties, and antifungal susceptibility tests should be performed in clinical microbiology laboratories

Time-dependent surgical instrument contamination begins earlier in the uncovered table than in the covered table

Purpose Time-dependent surgical instrument contamination and the effect of covering during arthroplasty have not been investigated. This study aimed to evaluate time-dependent contamination of surgical instruments and the effect of covering on contamination as well as to perform bacterial typing of contaminated samples. The hypothesis was that covering the surgical instruments would decrease contamination rates. Methods Sixty patients who underwent total knee arthroplasty were randomized and divided into two groups: surgical instruments covered with a sterile towel or surgical instruments left uncovered. K-wires were used to extract microbiological samples. The K-wires were placed in a liquid culture medium at 0, 15, 30, 60, 90, and 120 min. After 24-h incubation period, samples from liquid cultures were cultured on blood agar using swabs. Samples with growth after 48 h were considered contaminated. Microscopic, staining, and biochemical properties were used for bacterial typing. Results Bacterial growth started after 30 and 60 min in the uncovered and covered groups, respectively. An increase in the number of K-wires contaminated with time was detected. At least 10,000 CFU/mL bacterial load was observed in the culture samples. Contamination was more significant in the uncovered group. A statistically significant difference in contamination was found between the uncovered and covered groups at 30-, 60-, 90-, and 120 min (p = 0.035, p = 0.012, p = 0.024, and p = 0.037, respectively). The most common bacteria on the contaminated instruments were coagulase-negative Staphylococci (60.4%), Staphylococcus aureus (22.9%), and Streptococcus agalactia (16.7%), respectively. Conclusion The risk of contamination increases with time. However, it may decrease if surgical instruments are covered. In the clinical practice, empiric antibiotic regimens based on the type of identified microorganisms in this study may be developed for postoperative periprosthetic joint infection prophylaxis