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Mozhgan Kheirandish,1 Behrooz Motlagh,2 Davoud Afshar1 1Department of Microbiology and Virology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran; 2Department of Clinical Biochemistry, School of Medicine, Zanjan University of Medical Sciences, Zanjan, IranCorrespondence: Davoud AfsharDepartment of Microbiology and Virology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, IranTel +98 2433140297Email afshar.d@zums.ac.irPurpose: Iron is a necessary element for the growth of bacteria; however, there are limited iron sources known for these microorganisms yet. Intracellular iron is stored as ferritin from, which releases iron in a gradual and controlled manner. The present study aimed to characterize ferritin-binding proteins (FBPs) of Streptococcus pneumoniae.Material and Methods: S. pneumoniae species were cultured in BHI broth containing ferritin (1094 ng/mL) for 4h at 37°C. Ferritin level was measured using ELISA assay. Bacterial proteome was electrophoresed on SDS-PAGE and then transferred on PVDF nitrocellulose membrane. Afterward, the PVDF membranes were incubated with a ferritin solution. Identification of ferritin binding proteins was performed using anti-ferritin monoclonal antibody conjugated with HRP enzyme. Molecular docking was used to assess the interaction between pneumococcal proteases and FBPs applying phenylmethylsulfonyl fluoride (PMSF) as a protease inhibitor.Results: No FBPs were identified in S. pneumoniae proteome. Moreover, ferritin levels have significantly (p< 0.05) decreased following the growth of S. pneumoniae in ferritin-rich BHI medium. Also, molecular docking showed that RadA protease, ClpP hydrolase, and HtrA protease can potentially interact with PMSF protease inhibitors. On the other hand, the addition of the PMSF to the culture of S. pneumoniae prevented the reduction of ferritin, which indicates a potential role of RadA, ClpP, and HtrA proteases in ferritin degradation.Conclusion: Our results suggest that S. pneumoniae produces no FBPs and also cannot directly use ferritin as an iron source. However, ferritin may be degraded through a protease-mediated mode.Keywords: Streptococcus pneumoniae, ferritin-binding proteins, proteome, iron

Solmaz Ohadian Moghadam,1 Davoud Afshar,2 Mohammad Reza Nowroozi,1 Amir Behnamfar,1 Amirreza Farzin1 1Uro-Oncology Research Center, Tehran University of Medical Sciences, Tehran, Iran; 2Department of Microbiology and Virology, Zanjan University of Medical Sciences, Zanjan, IranCorrespondence: Solmaz Ohadian MoghadamUro-Oncology Research Center, Tehran University of Medical Sciences, Tehran, IranTel/ Fax +98 21 66 43 77 25Email s-ohadian@sina.tums.ac.irPurpose: Given the importance of treatment failure due to multidrug-resistant (MDR) strains, studies on population structure of these organisms are necessary to improve control strategies. Accordingly, the current study aimed to determine the prevalence of carbapenem-resistant P. aeruginosa (CRPA) at a teaching referral hospital in Iran and to analyze their molecular clonality by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) for epidemiological purposes.Methods: In this study, modified Hodge test (MHT) and double-disk synergy test (DDST) were used for carbapenemase production and metallo-β-lactamases (MBLs) screening, respectively. All P. aeruginosa isolates were tested for antimicrobial resistance. Moreover, MBL genes (blaIMP, blaVIM, blaSPM, blaNDM) were detected by multiplex PCR assay.Results: Among 68 P. aeruginosa clinical isolates, 38 (55.88%) isolates were CRPA. Antibiotic susceptibility testing revealed that most of these isolates were MDR. PFGE analyses showed 5 common types and 27 single types among CRPA isolates. MLST analysis revealed three major clusters (MLST-sequence types (STs): 235, 357, and 861) among them. The 30 non-CRPA isolates corresponded mainly to MLST-STs 253, 360, and 446.Conclusion: Our results showed that internationally distributed MLST-STs with widely genomic diversity have spread in our hospital, and clonal expansion of MDR strains of P. aeruginosa was described as well.Keywords: carbapenem-resistant P. aeruginosa, CRPA, carbapenemase, metallo-β-lactamases, MBLs, multidrug-resistant, MDR, Pseudomonas aeruginosa, multilocus sequence typing, MLST, pulsed-field gel electrophoresis, PFGE