Authors:Azar Dokht Khosravi, Mohammad Reza Tabandeh, Fatemeh Shahi, and Shokrollah Salmanzadeh
The management of multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) presents a main challenge and the drug options for treating these infections are very limited. Linezolid (LNZ) has recently been approved for the treatment of MDR and XDR-TB. But, there are narrow data on genotypic and phenotypic LNZ resistance in clinical isolates. So, we aimed to determine the prevalence of LNZ resistance and to identify the mutations associated with LNZ resistance among clinical MDR-TB isolates. The minimum inhibitory concentration (MIC) values of LNZ for 22 MDR-TB isolates were determined by broth microdilution method. All MDR-TB isolates were sequenced in the rrl and rplC genes conferring LNZ resistance. LNZ resistance was found in 3 (13.6%) of 22 MDR-TB isolates. The MICs of LNZ were 8 μg/mL for two isolates and 16 μg/mL for one isolate. The 421 (A/G) and 449 (T/A) mutations in rplC gene were detected in one of the LNZ-resistant isolates. There was no mutation in rrl gene. The results reveal that the prevalence of LNZ-resistant isolates is 13.6% among MDR-TB isolates and drug susceptibility testing (DST) against LNZ is useful in the management of complicated and drug-resistant cases. However, further studies could identify other possible genetic mechanism of resistance in TB.
Authors:Saeed Khoshnood, Fatemeh Shahi, Nabi Jomehzadeh, Effat Abbasi Montazeri, Morteza Saki, Seyed Mojtaba Mortazavi, and Leila Maghsoumi-Norouzabad
The increasing resistance to macrolide, lincosamide, and streptogramin B agents among methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem for the health community. This study aimed to investigate the prevalence of ermA, ermB, ermC, and msrA in MRSA strains isolated from burn patients in Ahvaz, southwest of Iran. A total of 76 isolates of S. aureus were collected from January to May 2017 from Taleghani Burn Hospital in Ahvaz. Among 76 S. aureus strains collected, 60 (78.9%) isolates were MRSA. The antimicrobial susceptibility testing for MRSA showed extreme high resistance rate to clarithromycin (100%) and azithromycin (100%), followed by erythromycin (98.3%). The PCR assay revealed that the frequency rates of msrA, ermA, and ermC genes were 23 (38.3%), 28 (46.7%), and 22 (36.7%), respectively. In addition, none of the MRSA isolates had the ermB gene. Because of the high prevalence of macrolide and lincosamide resistance found in MRSA isolates from infections of burn patients in Ahvaz, southwest of Iran, it is recommended that local periodic survey be performed for controlling the dissemination of antimicrobial resistance.
Shigella spp. are a major cause of bacillary dysentery, particularly among children in developing countries such as Iran. This study aimed to investigate the presence of two important Shigella enterotoxins (ShET-1 and ShET-2), encoded by the set and sen genes, respectively, by polymerase chain reaction (PCR) assay among Shigella species isolated from children affected by shigellosis in Ahvaz, southwest of Iran. In this cross-sectional study, from June 2016 to April 2017, altogether 117 Shigella isolates were collected from fecal specimens of children aged <15 years with diarrhea in Ahvaz, southwest Iran. All isolates were identified by standard microbiological and molecular methods. The presence of enterotoxin genes was determined by PCR. The most prevalent isolate was Shigella flexneri (47.9%), followed by Shigella sonnei (41%) and Shigella boydii (11.1%), respectively. Shigella dysenteriae was not detected in patients’ samples. The frequencies of set1A, set1B, and sen genes were 5.1% (6/117), 15.4% (18/117), and 76.9% (90/117), respectively. This study provides initial background on the prevalence and distribution of the Shigella enterotoxin genes in Shigella isolates in southwest of Iran. In addition, this study revealed a high prevalence of sen enterotoxin gene in Shigella species.