Correlation of gyr Mutations with the Minimum Inhibitory Concentrations of Fluoroquinolones among Multidrug-Resistant Mycobacterium tuberculosis Isolates in Bangladesh

Fluoroquinolone (FQ) compounds—moxifloxacin (MOX), levofloxacin (LEV), and ofloxacin (OFL)—are used to treat multidrug-resistant tuberculosis (MDR-TB) globally. In this study, we investigated the correlation of gyr mutations among Mtb isolates with the MICs of MOX, LEV, and OFL in Bangladesh. A total of 50 MDR-TB isolates with gyr mutations, detected by the GenoType MTBDRsl assay, were subjected to drug susceptibility testing to determine the MICs of the FQs. Spoligotyping was performed to correlate the genetic diversity of the gyr mutant isolates with different MIC distributions. Among the 50 isolates, 44 (88%) had mutations in the gyrA gene, one (2%) had a mutation in the gyrB gene, and five (10%) isolates had unidentified mutations. The substitutions in the gyrA region were at A90V (n = 19, 38%), D94G (n = 16, 32%), D94A (n = 4, 8%), D94N/D94Y (n = 4, 8%), and S91P (n = 1, 2%), compared to the gyrB gene at N538D (n = 1.2%). D94G mutations showed the highest MICs for MOX, LEV, and OFL, ranging between 4.0 and 8.0 μg/mL, 4.0 and 16.0 μg/mL, and 16.0 and 32.0 μg/mL, respectively; while the most common substitution of A90V showed the lowest ranges of MICs (1.0–4.0 μg/mL, 2.0–8.0 μg/mL, and 4.0–32.0 μg/mL, respectively). Spoligotyping lineages demonstrated no significant differences regarding the prevalence of different gyr mutations. In conclusion, the substitutions of codon A90V and D94G in the gyr genes were mostly responsible for the FQs’ resistance among Mtb isolates in Bangladesh. Low levels of resistance were associated with the substitutions of A90V, while the D94G substitutions were associated with a high level of resistance to all FQs.

Detection and Testing Pathogenicity of Xanthomonas axonopodis pv. punicae Causing Bacterial Blight on Pomegranate

Pomegranate, one of the most important fruit crops, is constantly challenged by Bacterial blight caused by Xanthomonas axonopodispv. punicae, is a prevalent and destructive pomegranate disease. Accurate diagnosis of disease is very important to manage the disease. PCR have been widely used to detect or verify the presence of pathogen in recent decades. These molecular-based methods are rapid, accurate and sensitive for detecting pathogens. In this study, a primer set KKM5 and KKM6 was used and amplification of 491bp of gyrB gene proved the presence of Xap. The pathogenicity of the Xap was confirmed following Koch’s postulates.

DESAIN IN SILICO DNA PROBE PENDETEKSI MUTASI DAERAH RESISTENSI QUINOLON Gen gyrA DAN gyrB Mycobacterium tuberculosis

Fluoroquinolone (FQ) is the main drug used in MDR-TB therapy resistance to FQ can cause death and increase the risk of treatment failure in MDR-TB patients. Mutations in gyrA gene and gyrB gene from Mycobacterium tuberculosis are responsible for the occurrence of FQ resistance. The highest mutation of gyrA gene in QRDR was found in codon 94, while mutations in gyrB gene was found in codon 500. M. Tuberculosis which resistant to FQ can be detected using the Real Time Polymerase Chain Reaction (RT-PCR) method with DNA probe. This study will design the nucleotide sequence of the TaqMan type probe using the Clone Manager Suite 9.2 program. The results of the DNA probe design were then analyzed in two stages, which is based on the probe criteria in general and based on the TaqMan probe labeling criteria. The design of the mutant probe DNA using the program produced 1 probe for Asp94Ala specific mutations in the gyrA gene and 33 probes for Asp500Ala specific mutations in the gyrB gene. After being analyzed by the two criteria, it was obtained the A94MA1 probe with the 5 '-TCGATCTACGCCAGCCTGGT-3' sequence and B500MA12 probe with the order of 5 '-TACCACAAGCTCGTGCTGATGGC-3'. The results of these probes meet both criteria and can be used to detect mutations in codon 94 gyrA genes and codons 500 gyrB genes of Mycobacterium tuberculosis.

Goat Colostrum—Source of Toxigenic Bacillus Cereus

The aim of this study was to evaluate the toxigenic potential of Bacillus cereus strains isolated from frozen goat colostrum. Of the 50 phenotypically suspected B. cereus isolates, 39 (78.0 %) were confirmed as B. cereus by the polymerase chain reaction (PCR) method based on the gyrB gene detection. In these isolates, genes encoding the production of haemolysin BL (Hbl), a complex of non-haemolytic enterotoxins (Nhe) and emetic toxin were detected by the PCR method. In 36 (92.3 %) confirmed B. cereus isolates, genes encoding at least one type of toxins of interest were detected. In all toxigenic isolates, we found the presence of genes for Nhe production, and in 16 (41.0 %) of the isolates, genes encoding both Nhe and haemolysin BL were shown. Eight (20.5 %) of the emetic strains of B. cereus were identified. The emetic toxin production gene was always detected simultaneously with genes encoding non-haemolytic enterotoxin production. The ability to produce BL haemolysin and non-haemolytic enterotoxins were confirmed by the immunochromatographic method. In summary, goat colostrum can be a significant source of toxigenic strains of B. cereus.

Detection of Pseudomonas aeruginosa in Clinical Samples Using PCR Targeting ETA and gyrB Genes

Pseudomonas aeruginosa has variety of virulence factors that contribute to its pathogenicity. Therefore, rapid detection with high accuracy and specificity is very important in the control of this pathogenic bacterium. To evaluate the accuracy and specificity of Polymerase Chain Reaction (PCR) assay, ETA and gyrB genes were targeted to detect pathogenic strains of P. aeruginosa. Seventy swab samples were taken from patients with infected wounds and burns in two hospitals in Erbil and Koya cities in Iraq. The isolates were traditionally identified using phenotypic methods, and DNA was extracted from the positive samples, to apply PCR using the species specific primers targeting ETA, the gene encoding for exotoxin A, and gyrB gene. The results of this study indicate that 100% of P. aeruginosa isolates harbored the gyrB gene, whereas 74% of these isolates harbored ETA gene. However, the specificity of PCR for detection of P. aeruginosa based on the both genes was 100%, since no amplified product obtained using DNA extracted from other bacterial species. Hence by considering the importance of rapid detection of this bacterium due to the presence of problems in biochemical methods, PCR targeting multiple virulence genes is suggested in identification of pathogenic strains of P. aeruginosa isolated from some infections which should speed diagnosis of an antimicrobial therapy.