Emergence of colistin resistant Acinetobacter baumannii clonal complex 2 (CC2) among hospitalized patients in Iran.

Acinetobacter baumannii is a major causative agent of serious nosocomial infections. This study was carried out to investigate the molecular characterization of colistin resistant isolates of A. baumannii from hospitalized patients, based on multilocus sequence typing (MLST). A cross-sectional study was conducted to collect A. baumannii from clinical samples in Isfahan from 2021 to 2022. Isolates were identified as A. baumannii using biochemical tests and PCR of blaOXA-51. Antibiotic susceptibility testing was carried out using the Kirby-Bauer method and minimum inhibitory concentration (MIC) values were determined for colistin. Additionally, MLST was performed according to the Pasteur scheme to assess the relationship between colistin resistant A. baumannii. A total of 70 non-repetitive A. baumannii isolates were obtained from different clinical samples. MIC results showed that seven A. baumannii isolates were resistant to colistin. The antibiotic susceptibility pattern revealed that all seven colistin resistant strains were resistant to all tested antibiotics. Based on MLST analysis, the colistin resistant isolates were assigned to five unique STs namely, ST2 (3; 42.9%) followed by ST78 (1; 14.3%), ST1077 (1; 14.3%), ST415 (1; 14.3%) and ST391 (1; 14.3%). Among them ST2, ST391 and ST415 belong to clonal complex 2. Colistin resistant A. baumannii ST2 is the main circulating clone in clinical settings in Iran, but additionally ST415, ST391, and ST1077 are found for the first time in our country. Intensive control procedures and strict adherence to surveillance programs are recommended to decrease the spread of carbapenem and colistin resistant A. baumannii strain.

Real-Time Assay as A Tool for Detecting lytA Gene in Streptococcus pneumoniae Isolates.

OBJECTIVE: In-time diagnosis of Streptococcus pneumoniae (S. pneumonia) can play a significant role in decreasing morbidity and mortality rate. Applying molecular methods has gained popularity due to the existing limits of routine diagnostic methods. Examining the expression of different genes of this bacterium through different molecular methods suggests that lytA gene has a higher sensitivity and specificity in diagnosis of Streptococcus pneumoniae. The aim of this study was to evalutate lytA gene expression in diagnosis of invasive S. pneumonia in culture positive specimens by real-time polymerase chain reaction (PCR). MATERIALS AND METHODS: IIn this a descriptive study, All received specimens were isolated to identify S. pneumoniae. DNA was then extracted and after optimizing the test and determining the detection limit, samples were tested by real-time PCR using lytA gene primers. RESULTS: Twenty seven isolates were diagnosed as S. pneumoniae. In all, the extracted DNA was positive in real-time method. The electrophoresis of the products also confirmed the presence of single product b along with the 53 base pair fragment. The detection limit of the test was less 6 colony forming unit (CFU). CONCLUSION: Real-Time PCR seems to provide reliable and rapid results. We suggest that this test should be conducted on the preliminary isolated specimens, since applying various biochemical tests need one extra working day.