In this study, we examined the association between antimicrobial resistance, CRISPR/Cas systems and virulence with phage susceptibility in Acinetobacter baumannii and investigated draft genomes of ...phage susceptible multidrug resistant A. baumannii strains from Thailand. We investigated 230 A. baumannii strains using 17 lytic A. baumannii phages and the phage susceptibility was 46.5% (107/230). Phage susceptibility was also associated with resistance to numerous antibiotics (p-value < 0.05). We also found association between biofilm formation and the presence of ompA gene among phage susceptible A. baumannii strains (p-value < 0.05). A. baumannii isolates carrying cas5 or combinations of two or three other cas genes, showed a significant increase in phage resistance. Whole-genome sequences of seven phage susceptible A. baumannii isolates revealed that six groups of antibiotic resistance genes were carried by all seven phage susceptible A. baumannii. All strains carried biofilm associated genes and two strains harbored complete prophages, acquired copper tolerance genes, and CRISPR-associated (cas) genes. In conclusion, our data exhibits an association between virulence determinants and biofilm formation among phage susceptible A. baumannii strains. These data help to understand the bacterial co-evolution with phages.
Background Staphylococcus aureus is one of the most common pathogens responsible for food poisoning due to its ability to produce staphylococcal enterotoxin (SE). S. aureus can form biofilms on the ...surfaces of food processing devices, enabling the distribution of SE on foods through cross-contamination events. Thailand is known for its exotic cuisine, but there is no data on the prevalence of SE-harboring S. aureus in restaurants in Thailand. Methods In this study, we conducted surface swabs on surfaces of kitchen utensil that come into contact with food and on the hands of food handlers working in restaurants in the north part of Thailand. Isolated S. aureus was investigated for biofilm formation, virulence, and SE genes. Results Two hundred S. aureus were isolated from 650 samples. The highest prevalence of S. aureus contamination was detected on the hands of food handlers (78%), followed by chopping boards (26%), plates (23%), knives (16%), spoons (13%), and glasses (5%). All of them were methicillin-sensitive S. aureus (MSSA) and the mecA gene was not present in any strains. Biofilm formation was detected using the CRA method, and 49 (24.5%) were identified as biofilm-producing strains, with the hands of food handlers identified as the primary source of biofilm-producing strains. The prevelence of biofilm-related adhesion genes detected were: icaAD (13%), fnbA (14.5%), cna (6.5%), and bap (0.5%). Two classical enterotoxin genes, sec and sed, were also found in four and six of the S. aureus isolates, respectively, from hands and utensils. Conclusion The highest prevelence of S. aureus was detected on the hands of food handlers. S. aureus strains with biofilm and enterotoxin production abilities were discovered on food contact surfaces and the hands of food handlers, implying significant risk of food contamination from these sources that could be harmful to consumers. To avoid cross-contamination of food with food contact items, the food handlers' hands should be properly washed, and all food preparation equipment should be thoroughly cleaned.
This study utilized integrative bioinformatics’ tools together with phenotypic assays to understand the whole-genome features of a carbapenem-resistant international clone II Acinetobacter baumannii ...AB073. Overall, we found the isolate to be resistant to seven antibiotic classes, penicillins, β-lactam/β-lactamase inhibitor combinations, cephalosporins, carbapenems, aminoglycosides, fluoroquinolones, and folate pathway antagonists. These resistance phenotypes are related to various chromosomal-located antibiotic resistance determinants involved in different mechanisms such as reduced permeability, antibiotic target protection, antibiotic target alteration, antibiotic inactivation, and antibiotic efflux. IC2 A. baumannii AB073 could not transfer antibiotic resistance by conjugation experiments. Likewise, mobilome analysis found that AB073 did not carry genetic determinants involving horizontal gene transfer. Moreover, this isolate also carried multiple genes associated with the ability of iron uptake, biofilm formation, immune invasion, virulence regulations, and serum resistance. In addition, the genomic epidemiological study showed that AB073-like strains were successful pathogens widespread in various geographic locations and clinical sources. In conclusion, the comprehensive analysis demonstrated that AB073 contained multiple genomic determinants which were important characteristics to classify this isolate as a successful international clone II obtained from Thailand.
Objective:To investigate the prevalence of Candida spp.and the virulence factors of Candida albicans(C.albicans) isolated from external surfaces of blow flies collected from Mae Sot,Tak ...Province,Thailand.Methods:The blow flies were collected by sterile sweep nets from three areas in Mae Sot.Yeast isolation was first performed on Sabouraud dextrose agar(SDA) supplemented with chloramphenicol and cycloheximide.The yeast isolates were then identified by using chromogenic agar,a yeast identification test kit,a germ tube formation test and a carbohydrate utilization test.The β-hemolysis was determined on 7% sheep blood agar,while phospholipase activity was measured on SDA agar supplemented with 10% egg yolk suspension.Antifungal susceptibility testing was determined by broth micro-dilution testing against ketoconazole and amphotericin B.Results:The prevalence rate of Candida spp.on the external surfaces of the blow flies was 78.1%.All C.albicans isolated from the blow fly demonstrated b-hemolysin and potent phospholipase activities and 47.1% of C.albicans were resistant to ketoconazole with MIC values 128 mg/m L.Conclusions:The results indicate that blow flies could play an essential role in the transmission of potentially pathogenic and antifungal resistant C.albicans into the environment.Further investigation on other virulence factors and genetic relatedness among isolates from the blow flies,the environment and clinical specimens is required to confirm this role.
Molecular chaperone Hsp104, also known as heat shock protein in yeast Saccharomyces cerevisiae, plays an essential role in thermotorelance response enabling yeast cell survival at high temperature. ...Hsp104 mediates the misfolding and the aggregation of denatured proteins to refold to their native forms. In addition, it has also reported that Hsp104 protein is required to maintain and propagate the prion state within yeast cells. A prion is an unusual form of protein or misfolded protein and prone to aggregate as large protein polymers. Yeast prion can be transmitted from cell to cell like prions found in humans but does not cause disease. Several studies have revealed that Hsp104 is involved in yeast PSI+ prion propagation by dissolving prion polymer into the smaller molecules needed to generate a new round of propagation via the same mechanism of Hsp104 in promoting proteins refolding. Interestingly, over-expression of Hsp104, results in elimination of the PSI+ prion from yeast cells but the mechanism remains unclear. Therefore, it is necessary to gain insight into the mechanism of how elevated Hsp104 induces PSI+ loss. Furthermore, this information might lead to further treatment of human neurodegenerative diseases caused by misfolding and accumulation of abnormal proteins in the brain.
Summary
The ability of a yeast cell to propagate PSI+, the prion form of the Sup35 protein, is dependent on the molecular chaperone Hsp104. Inhibition of Hsp104 function in yeast cells leads to a ...failure to generate new propagons, the molecular entities necessary for PSI+ propagation in dividing cells and they get diluted out as cells multiply. Over‐expression of Hsp104 also leads to PSI+ prion loss and this has been assumed to arise from the complete disaggregation of the Sup35 prion polymers. However, in conditions of Hsp104 over‐expression in PSI+ cells we find no release of monomers from Sup35 polymers, no monomerization of aggregated Sup35 which is not accounted for by the proportion of prion‐free psi‐ cells present, no change in the molecular weight of Sup35‐containing SDS‐resistant polymers and no significant decrease in average propagon numbers in the population as a whole. Furthermore, they show that over‐expression of Hsp104 does not interfere with the incorporation of newly synthesised Sup35 into polymers, nor with the multiplication of propagons following their depletion in numbers while growing in the presence of guanidine hydrochloride. Rather, they present evidence that over‐expression of Hsp104 causes malpartition of PSI+ propagons between mother and daughter cells in a sub‐population of cells during cell division thereby generating prion‐free psi− cells.
Curing a prion by over‐expressing Hsp104, a disaggregase‐chaperone, does not involve detectable disaggregation of the prion amyloid aggregates, but does cause their retention in mother cells at cell division. Chart: Retention of hereditary prions of Sup35 (eRF3) in mother cells (red box) after over‐expression of Hsp104. Inset: PRION+ (white) and prion‐ colonies and sectors seen after 3 generations of Hsp104 over‐expression. White sectors derive from the mother cell of a dividing pair.
Acinetobacter baumannii
is an important opportunistic pathogen, usually associated with immunocompromised individuals with a prolonged period of stay in a hospital. Currently, the incidence of ...multi-drug resistant
A. baumannii
(MDR-AB) and extensively drug-resistant
A. baumannii
(XDR-AB) is increasing rapidly in Thailand, mirroring the trend worldwide. Novel therapeutic approaches for the treatment of
A. baumannii
infection using bacteriophages are being evaluated, and the use of phage-derived peptides is being tested as alternative approach to fighting infection. In this study, we isolated and determined the biological features of a lytic
A. baumannii
phage called vB_AbaAut_ChT04 (vChT04). The vChT04 phage was classified as a member of the family
Autographiviridae
of the class
Caudoviricetes
. It showed a short latent period (10 min) and a large burst size (280 PFU cell
−1
), and it was able to infect 52 out of 150 clinical MDR-AB strains tested (34.67%). Most of the phage-sensitive strains were
A. baumannii
strains that had been isolated during the same year that the phage was isolated. The phage showed activity across a broad pH (pH 5.0–8.0) and temperature (4–37°C) range. Whole-genome analysis revealed that the vChT04 genome comprises 41,158 bp with a 39.3% GC content and contains 48 open reading frames (ORFs), 28 of which were assigned putative functions based on homology to previously identified phage genes. Comparative genomic analysis demonstrated that vChT04 had the highest similarity to phage vB_AbaP_WU2001, which was isolated in the southern part of Thailand. An endolysin gene found in the vChT04 genome was used to synthesize an antimicrobial peptide (designated as PLysChT04) and its antimicrobial activity was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. The MIC and MBC values of peptide PLysChT04 against MDR-AB and XDR-AB were 312.5–625 µg/mL, and it was able to inhibit both phage-susceptible and phage-resistant isolates collected over different time periods. PLysChT04 showed good efficacy in killing drug-resistant
A. baumannii
and other bacterial strains, and it is a promising candidate for development as an alternative therapeutic agent targeting
A. baumannii
infections.
Summary
The ability of a yeast cell to propagate
PSI
+
, the prion form of the Sup35 protein, is dependent on the molecular chaperone Hsp104. Inhibition of Hsp104 function in yeast cells leads to a ...failure to generate new propagons, the molecular entities necessary for
PSI
+
propagation in dividing cells and they get diluted out as cells multiply. Over‐expression of Hsp104 also leads to
PSI
+
prion loss and this has been assumed to arise from the complete disaggregation of the Sup35 prion polymers. However, in conditions of Hsp104 over‐expression in
PSI
+
cells we find no release of monomers from Sup35 polymers, no monomerization of aggregated Sup35 which is not accounted for by the proportion of prion‐free
psi
‐
cells present, no change in the molecular weight of Sup35‐containing SDS‐resistant polymers and no significant decrease in average propagon numbers in the population as a whole. Furthermore, they show that over‐expression of Hsp104 does not interfere with the incorporation of newly synthesised Sup35 into polymers, nor with the multiplication of propagons following their depletion in numbers while growing in the presence of guanidine hydrochloride. Rather, they present evidence that over‐expression of Hsp104 causes malpartition of
PSI
+
propagons between mother and daughter cells in a sub‐population of cells during cell division thereby generating prion‐free
psi
−
cells.
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