Background: COVID-19 is known as a new viral infection. Viral-bacterial co-infections are one of the biggest medical concerns, resulting in increased mortality rates. To date, few studies have investigated bacterial superinfections in COVID-19 patients. Hence, we designed the current study on COVID-19 patients admitted to ICUs. Methods: Nineteen patients admitted to our ICUs were enrolled in this study. To detect COVID-19, reverse transcription real-time polymerase chain reaction was performed. Endotracheal aspirate samples were also collected and cultured on different media to support the growth of the bacteria. After incubation, formed colonies on the media were identified using Gram staining and other biochemical tests. Antimicrobial susceptibility testing was carried out based on the CLSI recommendations. Results: Of nineteen COVID-19 patients, 11 (58%) patients were male and 8 (42%) were female, with a mean age of 67 years old. The average ICU length of stay was~15 days and at the end of the study, 18 cases (95%) expired and only was 1 case (5%) discharged. In total, all patients were found positive for bacterial infections, including seventeen Acinetobacter baumannii (90%) and two Staphylococcus aureus (10%) strains. There was no difference in the bacteria species detected in any of the sampling points. Seventeen of 17 strains of Acinetobacter baumannii were resistant to the evaluated antibiotics. No metallo-beta-lactamases-producing Acinetobacter baumannii strain was found. One of the Staphylococcus aureus isolates was detected as methicillin-resistant Staphylococcus aureus and isolated from the patient who died, while another Staphylococcus aureus strain was susceptible to tested drugs and identified as methicillin-sensitive Staphylococcus aureus. Conclusions: Our findings emphasize the concern of superinfection in COVID-19 patients due to Acinetobacter baumannii and Staphylococcus aureus. Consequently, it is important to pay attention to bacterial co-infections in critical patients positive for COVID-19.
In this study, we report the insertion sequence ISPpu21 in the oprD porin gene of carbapenem-resistant Pseudomonas aeruginosa isolates from burn patients in Tehran, Iran. Antibiotic susceptibility tests for P. aeruginosa isolates were determined. Production of metallo-β-lactamases (MBLs) and carbapenemase was evaluated and the β-lactamase-encoding and aminoglycoside-modifying enzyme genes were investigated by PCR and sequencing methods. The mRNA transcription level of oprD and mex efflux pump genes were evaluated by real-time PCR. The outer membrane protein profile was determined by SDS–PAGE. The genetic relationship between the P. aeruginosa isolates was assessed by random amplified polymorphic DNA PCR. In all, 10.52% (10/95) of clinical isolates of P. aeruginosa harboured the ISPpu21 insertion element in the oprD gene. The extended-spectrum β-lactamase-encoding gene in ISPpu21-carrying isolates was blaTEM. PCR assays targeting MBL and carbapenemase-encoding genes were also negative in all ten isolates. The rmtA, aadA, aadB and armA genes were positive in all ISPpu21 harbouring isolates. The relative expression levels of the mexX, mexB, mexT and mexD genes in ten isolates ranged from 0.1- to 1.4-fold, 1.1- to 3.68-fold, 0.3- to 8.22-fold and 1.7- to 35.17-fold, respectively. The relative expression levels of the oprD in ten isolates ranged from 0.57- to 35.01-fold, which was much higher than those in the control strain P. aeruginosa PAO1. Evaluation of the outer membrane protein by SDS–PAGE suggested that oprD was produced at very low levels by all isolates. Using random amplified polymorphic DNA PCR genotyping, eight of the ten isolates containing ISPpu21 were shown to be clonally related. The present study describes a novel molecular mechanism, ISPpu21 insertion of the oprD gene, associated with carbapenem resistance in clinical P. aeruginosa isolates.
Stenotrophomonas maltophilia is an environmental Gram-negative bacterium that has rapidly emerged as an important nosocomial pathogen in hospitalized patients. Treatment of S. maltophilia infections is difficult due to increasing resistance to multiple antibacterial agents. The purpose of this study was to determine the phenotypic and genotypic characterization of S. maltophilia isolates recovered from patients referred to several hospitals. A total of 164 clinical isolates of S. maltophilia were collected from hospitals in various regions in Iran between 2016 and 2017. Antibiotic susceptibility testing was performed by disc diffusion method and E-test assay according to the Clinical and Laboratory Standards Institute (CLSI) guideline. The ability of biofilm formation was assessed with crystal violet staining and then, biofilm-associated genes were investigated by PCR-sequencing method. The presence of L1 (a metallo-β-lactamase), L2 (a clavulanic acid-sensitive cephalosporinase), sul1 and sul2 (resistance to Trimethoprim/Sulfamethoxazole), Sm qnr (intrinsic resistance to quinolones), and dfrA genes (dihydrofolate reductase enzyme that contributes to trimethoprim resistance) was also examined by PCR-sequencing. Relative gene expression of smeDEF efflux pump was assessed by real-time PCR. Genotyping was performed using the multi-locus sequencing typing (MLST) and repetitive extragenic palindromic-PCR (Rep-PCR). Isolates were resistant to imipenem (100%), meropenem (96%), doripenem (96%), and ceftazidime (36.58%). Notably, 5 (3.04%) isolates showed resistant to trimethoprim-sulfamethoxazole (TMP-SMX), an alarming trend of decreased susceptibility to TMP-SMX in Iran. Minocycline and levofloxacin exhibited the highest susceptibility of 91.46 and 99.39%, respectively. Using the crystal violet staining, 157 (95.73%) isolates had biofilm phenotype: 49 (29.87%), 63 (38.41%), and 45 (27.43%) isolates were categorized as strong-, moderate- and weak-biofilm producer while 7 isolates (4.26%) were identified a non-biofilm producer. Biofilm genes had an overall prevalence of 145 (88.41%), 137 (83.53%), and 164 (100%) of rmlA , rpfF , and spgM , respectively. L1 , L2 , Smqnr , sul1 , and sul2 resistance genes were detected in 145 (88.41%), 156 (96.12%), 103 (62.80%), 89 (54.26%), and 92 (56.09%) isolates, respectively. None of the S. maltophilia isolates were positive for dfrA12 , dfrA17 , and dfrA27 genes. Gene expression analysis showed that smeD efflux system was overexpressed in two out ...
Aim: The aim of this study was designing a LAMP method for the rapid detection of Brucella and development of a sensitive quantitative-LAMP (Q-LAMP) assay for quantification of brucellosis. Methods and Results: In this study for the LAMP detection of the causative agent of brucellosis, we used specifically designed primers to target the omp25 conserved gene of Brucella spp. The sensitivity of the LAMP method was evaluated by preparing serial tenfold dilution of omp25 gene containing plasmid followed by performing the LAMP reaction. To improve the assay as a quantitative test, LAMP products in the serial dilution were evaluated by Loopamp real-time turbidimeter system and then standard curve was generated by plotting time threshold values against log of copy number. The assay specificity was evaluated using Brucella genomic DNA and a panel containing genomes of 11 gram-positive and gramnegative organisms. The LAMP assay was highly specific and no amplification products were observed from the non-Brucella organisms. The test sensitivity for visual detection of turbidity or fluorescent colour change and also agarose gel electrophoresis was 560 ng and 5Á6 ng, respectively. The lower limit of detection was 17 copies of the gene that could be detected in 50 min. Conclusions: The results of this study indicated that the LAMP assay is a simple, rapid, sensitive and specific technique for detection of Brucella spp. that may improve diagnostic potential in clinical laboratories. Significance and Impact of the Study: The LAMP assay because of the simplicity and low cost can be preferred to other molecular methods in the diagnosis of infectious diseases.
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