Search Results (5)

Background/Objectives: Achromobacter xylosoxidans and Achromobacter insuavis are emerging opportunistic pathogens. Several Resistance-Nodulation-cell Division (RND) efflux systems are involved in intrinsic or acquired antibiotic resistance (AxyABM, AxyXY-OprZ, and AxyEF-OprN). The aim of this study was to explore the resistance mechanisms in one-step mutants in which the efflux systems described to date are not involved: one mutant of A. insuavis AXX-A (AXX-A-Do1) and two mutants of A. xylosoxidans CIP102236 (CIP102236-El9 and CIP102236-Eo4) selected on fluoroquinolones. Methods: In vitro mutants were compared to parental isolates by WGS. RT–qPCR and gene inactivation were used to explore the role of the new efflux systems detected. Results: In the A. insuavis AXX-A mutant (AXX-A-Do1), WGS showed a substitution in the putative regulator of the new RND efflux system AinCDJ. The transporter gene ainD was 79-fold overexpressed in AXX-A-Do1, compared to its parental strain. The inactivation of ainD in AXX-A-Do1 led to a decrease in MICs of ciprofloxacin (8-fold), levofloxacin (8-fold), cefepime (≥8-fold), meropenem (4-fold), doripenem (4-fold), doxycycline (4-fold), minocycline (4-fold), tigecycline (4-fold) and chloramphenicol (≥8-fold). The MICs values obtained were similar to those of the parental strain AXX-A. The same approach allowed the detection of the new efflux system AxySUV in A. xylosoxidans CIP102236 mutants, in which substitutions in the putative AxySUV regulator were associated with the overexpression of the transporter gene axyU. axyU inactivation in the mutants led to a decrease in MICs of ciprofloxacin (8- to 16-fold), levofloxacin (4- to 8-fold), doripenem (4-fold), doxycycline (4-fold), minocycline (4-fold), and chloramphenicol (≥4-fold). Interestingly, axySUV is present in only about 50% of available A. xylosoxidans genomes, whereas ainCDJ is detected in all A. insuavis genomes. Conclusions: This study demonstrated that AinCDJ overproduction is involved in the acquired resistance of A. insuavis to cefepime, meropenem, doripenem, fluoroquinolones, minocycline, doxycycline, tigecycline, and chloramphenicol and that AxySUV overproduction is involved in the acquired resistance of A. xylosoxidans to meropenem, fluoroquinolones, minocycline, doxycycline, and chloramphenicol. Full article

The Achromobacter genus comprises 22 species and various genogroups. Some species with higher virulence or antibiotic resistance are more likely to cause chronic infections in people with cystic fibrosis (CF). Current identification methods often fail to accurately distinguish between the species or result in misidentifications due to biochemical similarities. This study aims to develop an accurate qPCR protocol for species-level identification that is applicable in clinical diagnostic laboratories. Whole-genome sequencing of clinical isolates from different Achromobacter species identified species-specific single-nucleotide polymorphisms (SNPs) in two 16S gene regions. Based on these SNPs, two sets of primers and qPCR probes were designed to generate unique identification profiles. Thermal profiles were optimized, and qPCR was performed on serial bacterial DNA dilutions to determine the detection limit (LOD). Four probes successfully identified three species: A. xylosoxidans, A. dolens, and A. insuavis. Two additional probes were designed for novel genotypes unrelated to publicly available sequences. The LOD ranged from 0.005 pg/µL to 1 pg/µL. Combined probes achieved 100% sensitivity, with specificity ranging from 97.95% to 100%. This qPCR protocol enables accurate species identification, overcoming the limitations of current methods, and represents a reliable tool for clinical diagnostics. Full article

Peru is one of the leading countries that produce and export specialty coffees, favorably positioned in the international markets for its physical and organoleptic cup qualities. In recent years, yellow coffee rust caused by the phytopathogenic fungus Hemileia vastatrix stands out as one of the main phytosanitary diseases that affect coffee culture yields. Many studies have demonstrated bacteria antagonistic activity against a number of phytopathogen fungi. In this context, the aim of this work was to select and characterize phyllospheric bacteria isolated from Coffea arabica with antagonistic features against coffee rust to obtain biocontrollers. For that purpose, a total of 82 phyllospheric bacteria were isolated from two coffee leaf rust-susceptible varieties, typica and caturra roja, and one tolerant variety, catimor. Of all the isolates, 15% were endophytic and 85% were epiphytes. Among all the isolates, 14 were capable of inhibiting the mycelial radial growth of Mycena citricolor, and Colletotrichum sp. 16S rRNA gene sequence-based analysis showed that 9 isolates were related to Achromobacter insuavis, 2 were related to Luteibacter anthropi and 1 was related to Rodococcus ceridiohylli, Achromobacter marplatensis and Pseudomonas parafulva. A total of 7 representative bacteria of each group were selected based on their antagonistic activity and tested in germination inhibition assays of coffee rust uredinospores. The CRRFLT7 and TRFLT8 isolates showed a high inhibition percentage of urediniospores germination (81% and 82%, respectively), similar to that obtained with the chemical control (91%). An experimental field assay showed a good performance of both strains against rust damage too, making them a promising alternative for coffee leaf rust biocontrol. Full article

Achromobacter species are emerging pathogens in cystic fibrosis with inherent resistance to several classes of antimicrobial agents. We exposed strains with wild-type antimicrobial susceptibility to ticarcillin and generated mutants with broad β-lactam resistance. Within the detection limit of the assay, the capability to develop mutational resistance was strain-specific and reproducible. Mutational resistance was observed for all three tested strains of Achromobacter ruhlandii, for one of seven strains of Achromobacter xylosoxidans, and for none of five strains of Achromobacter insuavis. All mutants were resistant to piperacillin-tazobactam, while minimal inhibitory concentration of several other β-lactams increased 4–32-fold. Whole genome sequencing identified 1–4 non-synonymous mutations in known genes per mutant. All mutants encoded amino acid substitutions in cell wall recycling proteins, primarily Mpl, and the observed resistance is probably caused by hyperproduction of OXA-114-like β-lactamases. Related, but not identical substitutions were detected in clinical strains expressing acquired antimicrobial resistance. Full article

Non-communicable diseases (NCDs) are the leading global cause of death. The World Health Organization (WHO) has endorsed the consumption of fruits and vegetables because they are rich in phytochemicals that sustainably ameliorate the occurrence of NCDs. Thai food contains many spices and vegetables with recognized health benefits. Quality control of plant samples encountered a bottleneck in the field and comparative studies of plant control origins including species or cultivar identification, growing area and appropriate harvesting time are limited. To address this issue, all plant samples used in this study were cultivated and controlled by the Department of Agriculture, Ministry of Agriculture and Cooperatives, Thailand. The samples were phytochemically screened and determined their health-promoting bioactivities via antioxidant activities and inhibition of NCD-related enzymes including lipase (obesity), α-amylase and α-glucosidase (diabetes), angiotensin-converting enzyme (hypertension), as well as acetylcholinesterase, butyrylcholinesterase and β-secretase (Alzheimer’s disease). The non-enzymatic reaction toward glycation was also evaluated. The results showed that Senegalia pennata subsp. insuavis (Lace) Maslin, Seigler & Ebinger, Citrus hystrix DC. and Solanum melongena ‘Kermit’ extracts exhibited high antioxidant activities. Moreover, Citrus hystrix DC. extract was a potent inhibitor against lipase, angiotensin-converting enzyme and butyrylcholinesterase, while Coriandrum sativum L. and Psophocarpus tetragonolobus (L.) DC. were potent anti-diabetic agents and Senegalia pennata subsp. insuavis (Lace) Maslin, and Seigler & Ebinger was a potent anti-glycation agent. Our data provide a comparative analysis of ten vegetables to encourage healthy food consumption and development to control NCDs in Thailand in the future. Full article