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In order to optimize the identification of molds with MALDI-TOF MS, three protein extraction-methodologies were evaluated against 44 isolates: water extraction (WE), zirconium extraction (ZE) and the provider's recommended method (PRM). Two data bases were compared, Bruker (BK) and Bruker+National Institutes of Health. Considering both databases, results were respectively as follows: correct identification (CI) at gender level, 10 and 16 by WE; 27 and 32 by ZE and 18 and 23 by PRM; CI at species level, 5 and 7 by WE; 17 and 20 by ZE and 11 and 14 by PRM; non-reliable identification, 18 and 12 by WE; 9 and 4 by ZE and by PRM. No peaks were observed in 16 by WE, 8 by ZE and 17 by PRM. ZE showed the best perfomance (p<0.05).

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Introduction: Mycoplasma genitalium (MG) is responsible for 15%-20% nongonococcal urethritis in men. In Argentina, the diagnosis is only performed by few laboratories. Single-dose 1 g azithromycin (AZM1D) treatment leads to emergence of macrolide resistance (mutations at 23S rRNA gene, region V, position 2058 or 2059). Recommendations include 5-day AZM (AZM5D) regimen, moxifloxacin as second-line therapy. Doxycycline is only 30% effective. Test of Cure (ToC) is advisable. Objective: The aim of this study was to describe the first two clinical cases of persistent and recurrent urethritis due to macrolide-resistant MG in Argentina. Methods: End point polymerase chain reaction (PCR) for diagnosis and ToC. Sanger sequencing analysis of mutations. Results: Case 1: A 26-year-old male patient with occasional heterosexual contacts and no history of sexually transmitted infections (STIs) complained urethral thick purulent discharge and dysuria (January 2018), with negative microbiological cultures and Chlamydia trachomatis PCR. The patient received ceftriaxone/AZM1D. However, symptoms persisted (April 2018). Later, doxycycline was prescribed for 1 month. Five days after treatment, the sample was referred to the STI national reference laboratory (NRL) and results were found positive for MG. The patient was given AZM5D. As a result, symptoms disappeared, posterior ToC was found negative, and retrospectively, sequencing 23S rRNA gene showed A2058G transition. Case 2: An 18-year-old male patient with stable heterosexual relationship complained of previous gonococcal urethritis and urethral serous exudate with inflammatory reaction (September 2017), with negative microbiological cultures. The patient received ceftriaxone and AZM1D as initial treatment. Later, he was given doxycycline for 10 days. On February 2018, symptoms reappeared and sample referred to the NRL was positive for MG (negative for other STIs). With AZM1D treatment, symptoms disappeared. After 1 month, the symptoms recurred. Results showed a new MG-positive sample (April 2018). AZM5D administration induced 2 weeks symptoms free and recurrence, requiring moxifloxacin treatment. Symptoms disappeared completely. Posterior ToC is negative. Subsequently, sequencing both samples referred to the NRL showed A2059G transition. Conclusion: The clinical cases presented notified the importance of early and accurate diagnosis of MG infections and use of adequate treatment schemes. We emphasized the relevance of monitoring and surveillance prevalence of macrolide-resistant MG in Argentina.