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Fulltext Integrating multiple genomic technologies to investigate an outbreak of carbapenemase-producing Enterobacter hormaechei

Roberts LW, Harris PNA, Forde BM, Ben Zakour NL, Catchpoole E, Stanton-Cook M, et al.

Nat Commun, 2020 01 24;11(1):466.
PMID: 31980604 DOI: 10.1038/s41467-019-14139-5

Carbapenem-resistant Enterobacteriaceae (CRE) represent an urgent threat to human health. Here we report the application of several complementary whole-genome sequencing (WGS) technologies to characterise a hospital outbreak of blaIMP-4 carbapenemase-producing E. hormaechei. Using Illumina sequencing, we determined that all outbreak strains were sequence type 90 (ST90) and near-identical. Comparison to publicly available data linked all outbreak isolates to a 2013 isolate from the same ward, suggesting an environmental source in the hospital. Using Pacific Biosciences sequencing, we resolved the complete context of the blaIMP-4 gene on a large IncHI2 plasmid carried by all IMP-4-producing strains across different hospitals. Shotgun metagenomic sequencing of environmental samples also found evidence of ST90 E. hormaechei and the IncHI2 plasmid within the hospital plumbing. Finally, Oxford Nanopore sequencing rapidly resolved the true relationship of subsequent isolates to the initial outbreak. Overall, our strategic application of three WGS technologies provided an in-depth analysis of the outbreak.

Matched MeSH terms: Bacterial Proteins/genetics*
Fulltext High Prevalence of Toxigenic and Nontoxigenic Clostridium difficile Strains in Malaysia

Riley TV, Collins DA, Karunakaran R, Kahar MA, Adnan A, Hassan SA, et al.

J Clin Microbiol, 2018 Jun;56(6).
PMID: 29563206 DOI: 10.1128/JCM.00170-18

Accumulating evidence shows a high prevalence of Clostridium difficile in Southeast Asia associated with a range of clinical presentations. However, severe infections are rarely reported. We investigated C. difficile infection (CDI) across four hospitals in Kuala Lumpur and Kota Bharu, Malaysia. Enzyme immunoassays for glutamate dehydrogenase (GDH) and toxin A or B were performed on diarrheal stool specimens collected from patients in 2015 and 2016. Specimens were also cultured and isolates of C. difficile characterized by PCR ribotyping and detection of toxin genes. In total, 437 specimens were collected and fecal toxin was detected in 3.0%. A further 16.2% of specimens were GDH positive and toxin negative. After culture, toxigenic strains were isolated from 10.3% and nontoxigenic strains from 12.4% of specimens. The most prevalent PCR ribotypes (RTs) were RT 017 (20.0%) and RT 043 (10.0%). The high prevalence of RT 017 and nontoxigenic strains in Malaysia and in neighboring Thailand and Indonesia suggests that they localize to the region of Southeast Asia, with an implication that they may mediate the burden of CDI in the region.

Matched MeSH terms: Bacterial Proteins/genetics*
Fulltext Protein engineering of selected residues from conserved sequence regions of a novel Anoxybacillus α-amylase

Ranjani V, Janeček S, Chai KP, Shahir S, Abdul Rahman RN, Chan KG, et al.

Sci Rep, 2014 Jul 28;4:5850.
PMID: 25069018 DOI: 10.1038/srep05850

The α-amylases from Anoxybacillus species (ASKA and ADTA), Bacillus aquimaris (BaqA) and Geobacillus thermoleovorans (GTA, Pizzo and GtamyII) were proposed as a novel group of the α-amylase family GH13. An ASKA yielding a high percentage of maltose upon its reaction on starch was chosen as a model to study the residues responsible for the biochemical properties. Four residues from conserved sequence regions (CSRs) were thus selected, and the mutants F113V (CSR-I), Y187F and L189I (CSR-II) and A161D (CSR-V) were characterised. Few changes in the optimum reaction temperature and pH were observed for all mutants. Whereas the Y187F (t1/2 43 h) and L189I (t1/2 36 h) mutants had a lower thermostability at 65°C than the native ASKA (t1/2 48 h), the mutants F113V and A161D exhibited an improved t1/2 of 51 h and 53 h, respectively. Among the mutants, only the A161D had a specific activity, k(cat) and k(cat)/K(m) higher (1.23-, 1.17- and 2.88-times, respectively) than the values determined for the ASKA. The replacement of the Ala-161 in the CSR-V with an aspartic acid also caused a significant reduction in the ratio of maltose formed. This finding suggests the Ala-161 may contribute to the high maltose production of the ASKA.

Matched MeSH terms: Bacterial Proteins/genetics
Improvement of cyclodextrin glycosyltransferase gene expression in Escherichia coli by insertion of regulatory sequences involved in the promotion of RNA transcription

Ramli N, Abd-Aziz S, Alitheen NB, Hassan MA, Maeda T

Mol Biotechnol, 2013 Jul;54(3):961-8.
PMID: 23338983 DOI: 10.1007/s12033-013-9647-7

Regulation of RNA transcription in controlling the expression of genes at promoter and terminator regions is crucial as the interaction of RNA polymerase occurred at both sites. Gene encoding cyclodextrin glycosyltransferase (CGTase) from Bacillus sp. NR5 UPM isolated in the previous study was used for further construction of pTZCGT-SS, pTZCGT-BS and pTZCGT-BT expression systems for enhancement of CGTase production. The putative promoter regions, -35 and -10 sequences were found in the upstream of the mature gene start codon. Whereas, long inverted repeats sequences which can form a stable stem and loop structure was found downstream of the open reading frame (ORF) of Bacillus sp. NR5 UPM CGTase. The construction of E. coli strain harbouring pTZCGT-BS showed increment of 3.2-fold in CGTase activity compared to the wild type producer. However, insertion of terminator downstream of CGTase gene in E. coli strain harbouring pTZCGT-BT only resulted in 4.42 % increment of CGTase production compared to E. coli strain containing pTZCGT-BS, perhaps due to low intrinsic termination efficiency. Thus, it is suggested that the insertion of the putative promoter regions upstream of the coding sequence for the construction of CGTase expression system will further enhance in the recombinant enzyme production.

Matched MeSH terms: Bacterial Proteins/genetics*
Sequence and structural investigation of a novel psychrophilic α-amylase from Glaciozyma antarctica PI12 for cold-adaptation analysis

Ramli AN, Azhar MA, Shamsir MS, Rabu A, Murad AM, Mahadi NM, et al.

J Mol Model, 2013 Aug;19(8):3369-83.
PMID: 23686283 DOI: 10.1007/s00894-013-1861-5

A novel α-amylase was isolated successfully from Glaciozyma antarctica PI12 using DNA walking and reverse transcription-polymerase chain reaction (RT-PCR) methods. The structure of this psychrophilic α-amylase (AmyPI12) from G. antarctica PI12 has yet to be studied in detail. A 3D model of AmyPI12 was built using a homology modelling approach to search for a suitable template and to generate an optimum target-template alignment, followed by model building using MODELLER9.9. Analysis of the AmyPI12 model revealed the presence of binding sites for a conserved calcium ion (CaI), non-conserved calcium ions (CaII and CaIII) and a sodium ion (Na). Compared with its template-the thermostable α-amylase from Bacillus stearothermophilus (BSTA)-the binding of CaII, CaIII and Na ions in AmyPI12 was observed to be looser, which suggests that the low stability of AmyPI12 allows the protein to work at different temperature scales. The AmyPI12 amino acid sequence and model were compared with thermophilic α-amylases from Bacillus species that provided the highest structural similarities with AmyPI12. These comparative studies will enable identification of possible determinants of cold adaptation.

Matched MeSH terms: Bacterial Proteins/genetics
cagA gene variants in Malaysian Helicobacter pylori strains isolated from patients of different ethnic groups

Ramelah M, Aminuddin A, Alfizah H, Isa MR, Jasmi AY, Tan HJ, et al.

FEMS Immunol. Med. Microbiol., 2005 May 1;44(2):239-42.
PMID: 15866222

Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3' region of cagA gene were examined among 192 Malaysian H. pylori cagA-positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621-651bp), type B (732-735bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p>0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific-cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p<0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p<0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection.

Matched MeSH terms: Bacterial Proteins/genetics*
Helicobacter pylori, ethnicity, and the gastroesophageal reflux disease spectrum: a study from the East

Rajendra S, Ackroyd R, Robertson IK, Ho JJ, Karim N, Kutty KM

Helicobacter, 2007 Apr;12(2):177-83.
PMID: 17309756

Ethnic differences in gastroesophageal reflux disease (GERD) and its complications as well as racial variations in the prevalence of Helicobacter pylori infection are well documented. Nevertheless, the association between reflux disease, H. pylori, and race has not been adequately explored.

Matched MeSH terms: Bacterial Proteins/genetics
Fulltext Role of α-helical structure in organic solvent-activated homodimer of elastase strain K

Rahman RN, Salleh AB, Basri M, Wong CF

Int J Mol Sci, 2011;12(9):5797-814.
PMID: 22016627 DOI: 10.3390/ijms12095797

Recombinant elastase strain K overexpressed from E. coli KRX/pCon2(3) was purified to homogeneity by a combination of hydrophobic interaction chromatography and ion exchange chromatography, with a final yield of 48% and a 25-fold increase in specific activity. The purified protein had exhibited a first ever reported homodimer size of 65 kDa by SDS-PAGE and MALDI-TOF, a size which is totally distinct from that of typically reported 33 kDa monomer from P. aeruginosa. The organic solvent stability experiment had demonstrated a stability pattern which completely opposed the rules laid out in previous reports in which activity stability and enhancement were observed in hydrophilic organic solvents such as DMSO, methanol, ethanol and 1-propanol. The high stability and enhancement of the enzyme in hydrophilic solvents were explained from the view of alteration in secondary structures. Elastinolytic activation and stability were observed in 25 and 50% of methanol, respectively, despite slight reduction in α-helical structure caused upon the addition of the solvent. Further characterization experiments had postulated great stability and enhancement of elastase strain K in broad range of temperatures, pHs, metal ions, surfactants, denaturing agents and substrate specificity, indicating its potential application in detergent formulation.

Matched MeSH terms: Bacterial Proteins/genetics
Fulltext Expression of an organic solvent stable lipase from Staphylococcus epidermidis AT2

Rahman RN, Kamarudin NH, Yunus J, Salleh AB, Basri M

Int J Mol Sci, 2010;11(9):3195-208.
PMID: 20957088 DOI: 10.3390/ijms11093195

An organic solvent tolerant lipase gene from Staphylococcus epidermidis AT2 was successfully cloned and expressed with pTrcHis2 in E. coli TOP10. Sequence analysis revealed an open reading frame (ORF) of 1,933 bp in length which coded for a polypeptide of 643 amino acid residues. The polypeptide comprised of a signal peptide (37 amino acids), pro-peptide and a mature protein of 390 amino acids. Expression of AT2 lipase resulted in an 18-fold increase in activity, upon the induction of 0.6 mM IPTG after a 10 h incubation period. Interestingly, this lipase was stable in various organic solvents (25% (v/v), mainly toluene, octanol, p-xylene and n-hexane). Literature shows that most of the organic solvent stable bacterial lipases were produced by Pseudomonas sp. and Bacillus sp., but very few from Staphylococcus sp. This lipase demonstrates great potential to be employed in various industrial applications.

Matched MeSH terms: Bacterial Proteins/genetics
A new organic solvent tolerant protease from Bacillus pumilus 115b

Rahman RN, Mahamad S, Salleh AB, Basri M

J Ind Microbiol Biotechnol, 2007 Jul;34(7):509-17.
PMID: 17492323

Five out of the nine benzene-toulene-ethylbenzene-xylene (BTEX) tolerant bacteria that demonstrated high protease activity on skim milk agar were isolated. Among them, isolate 115b identified as Bacillus pumilus exhibited the highest protease production. The protease produced was stable in 25% (v/v) benzene and toluene and it was activated 1.7 and 2.5- fold by n-dodecane and n-tetradecane, respectively. The gene encoding the organic solvent tolerant protease was cloned and its nucleotide sequence determined. Sequence analysis revealed an open reading frame (ORF) of 1,149 bp that encoded a polypeptide of 383 amino acid residues. The polypeptide composed of 29 residues of signal peptide, a propeptide of 79 residues and a mature protein of 275 amino acids with a calculated molecular mass of 27,846 Da. This is the only report available to date on organic solvent tolerant protease from B. pumilus.

Matched MeSH terms: Bacterial Proteins/genetics
Molecular investigation of a gene encoding organic solvent-tolerant alkaline protease from Pseudomonas aeruginosa strain K

Rahman RN, Geok LP, Wong CF, Basri M, Salleh AB

J Basic Microbiol, 2010 Apr;50(2):143-9.
PMID: 20082370 DOI: 10.1002/jobm.200900133

A gene encoding an organic solvent-stable protease was amplified from Pseudomonas aeruginosa strain K by polymerase chain reaction using consensus primers based on multiple sequence alignment of alkaline and metalloprotease genes from Pseudomonas species. The gene, which consisted of 1440 bp nucleotides and deduced 479 amino acid residues, was successfully expressed in pGEX-4T-1 expression system in the presence of 1.0 mM IPTG, after an incubation of 6 h at 37 degrees C. Under these conditions, the recombinant strain K protease was, subsequently, released into the periplasm of E. coli BL21 (DE3) with an optimum proteolytic activity detected at 1.0112 U/ml. To date, this is the first reported expression of alkaline protease (aprA) with such remarkable property in Escherichia coli.

Matched MeSH terms: Bacterial Proteins/genetics*
Secretory expression of thermostable T1 lipase through bacteriocin release protein

Rahman RN, Leow TC, Basri M, Salleh AB

Protein Expr Purif, 2005 Apr;40(2):411-6.
PMID: 15766884

The extracellular production of T1 lipase was performed by co-expression of pJL3 vector encoding bacteriocin release protein in prokaryotic system. Secretory expression was optimized by considering several parameters, including host strains, inducer (IPTG) concentration, media, induction at A(600 nm), temperature, and time of induction. Among the host strains tested, Origami B excreted out 18,100 U/ml of lipase activity into culture medium when induced with 50 microM IPTG for 12 h. The Origami B harboring recombinant plasmid pGEX/T1S and pJL3 vector was chosen for further study. IPTG at 0.05 mM, YT medium, induction at A(600 nm) of 1.25, 30 degrees C, and 32 h of induction time were best condition for T1 lipase secretion with Origami B as a host.

Matched MeSH terms: Bacterial Proteins/genetics
Occurrence of the vanA and vanC2/C3 genes in Enterococcus species isolated from poultry sources in Malaysia

Radu S, Toosa H, Rahim RA, Reezal A, Ahmad M, Hamid AN, et al.

Diagn Microbiol Infect Dis, 2001 Mar;39(3):145-53.
PMID: 11337180

Enterococcus species isolated from poultry sources were characterized for their resistance to antibiotics, plasmid content, presence of van genes and their diversity by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). The results showed that all isolates were multi-resistance to the antibiotics tested. Ampicillin (15/70) followed by chloramphenicol (37/70) were the most active antibiotics tested against the Enterococcus spp. isolates, while the overall resistant rates against the other antibiotics were between 64.3% to 100%. All vancomycin-resistant E. faecalis, E. durans, E. hirae and E. faecium isolates tested by the disk diffusion assay were positive in PCR detection for presence of vanA gene. All E. casseliflavus isolates were positive for vanC2/C3 gene. However, none of the Enterococcus spp. isolates were positive for vanB and vanC1 genes. Plasmids ranging in sizes between 1.1 to ca. 35.8 MDa were detected in 38/70 of the Enterococcus isolates. When the genetic relationship among all isolates of the individual species were tested by RAPD-PCR, genetic differences detected suggested a high genetic polymorphisms of isolates in each individual species. Our results indicates that further epidemiological studies are necessary to elucidate the role of food animals as reservoir of VRE and the public health significance of infections caused by Enterococcus spp.

Matched MeSH terms: Bacterial Proteins/genetics*
The FloR master regulator controls flotation, virulence and antibiotic production in Serratia sp. ATCC 39006

Quintero-Yanes A, Lee CM, Monson R, Salmond G

Environ Microbiol, 2020 07;22(7):2921-2938.
PMID: 32352190 DOI: 10.1111/1462-2920.15048

Serratia sp. ATCC 39006 produces intracellular gas vesicles to enable upward flotation in water columns. It also uses flagellar rotation to swim through liquid and swarm across semi-solid surfaces. Flotation and motility can be co-regulated with production of a β-lactam antibiotic (carbapenem carboxylate) and a linear tripyrrole red antibiotic, prodigiosin. Production of gas vesicles, carbapenem and prodigiosin antibiotics, and motility are controlled by master transcriptional and post-transcriptional regulators, including the SmaI/SmaR-based quorum sensing system and the mRNA binding protein, RsmA. Recently, the ribose operon repressor, RbsR, was also defined as a pleiotropic regulator of flotation and virulence factor elaboration in this strain. Here, we report the discovery of a new global regulator (FloR; a DeoR family transcription factor) that modulates flotation through control of gas vesicle morphogenesis. The floR mutation is highly pleiotropic, down-regulating production of gas vesicles, carbapenem and prodigiosin antibiotics, and infection in Caenorhabditis elegans, but up-regulating flagellar motility. Detailed proteomic analysis using TMT peptide labelling and LC-MS/MS revealed that FloR is a physiological master regulator that operates through subordinate pleiotropic regulators including Rap, RpoS, RsmA, PigU, PstS and PigT.

Matched MeSH terms: Bacterial Proteins/genetics
Fulltext Molecular characterization of clinical isolates of Aeromonas species from Malaysia

Puthucheary SD, Puah SM, Chua KH

PLoS One, 2012;7(2):e30205.
PMID: 22383958 DOI: 10.1371/journal.pone.0030205

BACKGROUND: Aeromonas species are common inhabitants of aquatic environments giving rise to infections in both fish and humans. Identification of aeromonads to the species level is problematic and complex due to their phenotypic and genotypic heterogeneity.
METHODOLOGY/PRINCIPAL FINDINGS: Aeromonas hydrophila or Aeromonas sp were genetically re-identified using a combination of previously published methods targeting GCAT, 16S rDNA and rpoD genes. Characterization based on the genus specific GCAT-PCR showed that 94 (96%) of the 98 strains belonged to the genus Aeromonas. Considering the patterns obtained for the 94 isolates with the 16S rDNA-RFLP identification method, 3 clusters were recognised, i.e. A. caviae (61%), A. hydrophila (17%) and an unknown group (22%) with atypical RFLP restriction patterns. However, the phylogenetic tree constructed with the obtained rpoD sequences showed that 47 strains (50%) clustered with the sequence of the type strain of A. aquariorum, 18 (19%) with A. caviae, 16 (17%) with A. hydrophila, 12 (13%) with A. veronii and one strain (1%) with the type strain of A. trota. PCR investigation revealed the presence of 10 virulence genes in the 94 isolates as: lip (91%), exu (87%), ela (86%), alt (79%), ser (77%), fla (74%), aer (72%), act (43%), aexT (24%) and ast (23%).
CONCLUSIONS/SIGNIFICANCE: This study emphasizes the importance of using more than one method for the correct identification of Aeromonas strains. The sequences of the rpoD gene enabled the unambiguous identication of the 94 Aeromonas isolates in accordance with results of other recent studies. Aeromonas aquariorum showed to be the most prevalent species (50%) containing an important subset of virulence genes lip/alt/ser/fla/aer. Different combinations of the virulence genes present in the isolates indicate their probable role in the pathogenesis of Aeromonas infections.

Matched MeSH terms: Bacterial Proteins/genetics
Fulltext Potential immunogenic polypeptides of Burkholderia pseudomallei identified by shotgun expression library and evaluation of their efficacy for serodiagnosis of melioidosis

Puah SM, Puthucheary SD, Chua KH

Int J Med Sci, 2013;10(5):539-47.
PMID: 23532805 DOI: 10.7150/ijms.5516

The search for novel immunogenic polypeptides to improve the accuracy and reliability of serologic diagnostic methods for Burkholderia pseudomallei infection is ongoing. We employed a rapid and efficient approach to identify such polypeptides with sera from melioidosis patients using a small insert genomic expression library created from clinically confirmed local virulent isolates of B. pseudomallei. After 2 rounds of immunoscreening, 6 sero-positive clones expressing immunogenic peptides were sequenced and their identities were: benzoate 1,2-dioxygenase beta subunit, a putative 200 kDa antigen p200, phosphotransferase enzyme family protein, short chain dehydrogenase and 2 hypothetical proteins. These immunogens were then transferred to an ELISA platform for further large scale screening. By combining shotgun expression library and ELISA assays, we identified 2 polypeptides BPSS1904 (benzoate 1,2-dioxygenase beta subunit) and BPSL3130 (hypothetical protein), which had sensitivities of 78.9% and 79.4% and specificities of 88.1% and 94.8%, respectively in ELISA test, thus suggesting that both are potential candidate antigens for the serodiagnosis of infections caused by B. pseudomallei.

Matched MeSH terms: Bacterial Proteins/genetics
Development of a species-specific PCR-RFLP targeting rpoD gene fragment for discrimination of Aeromonas species

Puah SM, Khor WC, Kee BP, Tan JAMA, Puthucheary SD, Chua KH

J Med Microbiol, 2018 Sep;67(9):1271-1278.
PMID: 30024365 DOI: 10.1099/jmm.0.000796

PURPOSE: The taxonomy of Aeromonas keeps expanding and their identification remains problematic due to their phenotypic and genotypic heterogeneity. In this study, we aimed to develop a rapid and reliable polymerase chain reaction-restriction fragment length polymorphism assay targeting the rpoD gene to enable the differentiation of aeromonads into 27 distinct species using microfluidic capillary electrophoresis.
METHODOLOGY: A pair of degenerate primers (Aero F: 5'-YGARATCGAYATCGCCAARCGB-3' and Aero R: 5'-GRCCDATGCTCATRCGRCGGTT-3') was designed that amplified the rpoD gene of 27 Aeromonas species. Subsequently, in silico analysis enabled the differentiation of 25 species using the single restriction endonuclease AluI, while 2 species, A. sanarelli and A. taiwanensis, required an additional restriction endonuclease, HpyCH4IV. Twelve type strains (A. hydrophila ATCC7966T, A. caviae ATCC15468T, A. veronii ATCC9071T, A. media DSM4881T, A. allosaccharophila DSM11576T, A. dhakensis DSM17689T, A. enteropelogens DSM7312T, A. jandaei DSM7311T, A. rivuli DSM22539T, A. salmonicida ATCC33658T, A. taiwanensis DSM24096T and A. sanarelli DSM24094T) were randomly selected from the 27 Aeromonas species for experimental validation.Results/key findings. The twelve type strains demonstrated distinctive RFLP patterns and supported the in silico digestion. Subsequently, 60 clinical and environmental strains from our collection, comprising nine Aeromonas species, were used for screening examinations, and the results were in agreement.
CONCLUSION: This method provides an alternative method for laboratory identification, surveillance and epidemiological investigations of clinical and environmental specimens.

Matched MeSH terms: Bacterial Proteins/genetics*
Diverse Profiles of Biofilm and Adhesion Genes in Staphylococcus Aureus Food Strains Isolated from Sushi and Sashimi

Puah SM, Tan JAMA, Chew CH, Chua KH

J Food Sci, 2018 Sep;83(9):2337-2342.
PMID: 30101982 DOI: 10.1111/1750-3841.14300

Staphylococcus aureus is able to form multilayer biofilms embedded within a glycocalyx or slime layer. Biofilm formation poses food contamination risks and can subsequently increase the risk of food poisoning. Identification of food-related S. aureus strains will provide additional data on staphylococcal food poisoning involved in biofilm formation. A total of 52 S. aureus strains isolated from sushi and sashimi was investigated to study their ability for biofilm formation using crystal violet staining. The presence of accessory gene regulator (agr) groups and 15 adhesion genes was screened and their associations in biofilm formation were studied. All 52 S. aureus strains showed biofilm production on the tested hydrophobic surface with 44% (23/52) strains classified as strong, 33% (17/52) as moderate, and 23% (12/52) as weak biofilm producers. The frequency of agr-positive strains was 71% (agr group 1 = 21 strains; agr group 2 = 2 strains; agr group 3 = 12 strains; agr group 4 = 2 strains) whereas agr-negative strains were 29% (15/52). Twelve adhesion genes were detected and 98% of the S. aureus strains carried at least one adhesion gene. The ebps was significantly (p < .05) associated with strong biofilm producing strains. In addition, eno, clfA, icaAD, sasG, fnbB, cna, and sasC were significantly higher in the agr-positive group compared to the agr-negative group. The results of this study suggest that the presence of ebps, eno, clfA, icaAD, sasG, fnbB, cna, and sasC may play an important role in enhancing the stage of biofilm-related infections and warrants further investigation.
PRACTICAL APPLICATION: This work contributes to the knowledge on the biofilm formation and the distribution of agr groups in S. aureus strains as well as microbial surface components in recognizing adherence matrix molecules of organisms isolated from ready-to-eat sushi and sashimi. The findings provide valuable information to further study the roles of specific genes in causing biofilm-related infections.

Matched MeSH terms: Bacterial Proteins/genetics*
Vibrio coralliirubri sp. nov., a new species isolated from mucus of red coral (Corallium rubrum) collected at Procida island, Italy

Poli A, Romano I, Mastascusa V, Buono L, Orlando P, Nicolaus B, et al.

Antonie Van Leeuwenhoek, 2018 Jul;111(7):1105-1115.
PMID: 29299771 DOI: 10.1007/s10482-017-1013-5

Strain Corallo1T was isolated from mucus of red coral (Corallium rubrum) at Punta Pizzaco (Procida island, Naples, Italy). It was characterised as a Gram-stain negative, motile, rod-shaped bacterium. Strain Corallo1T was found to show positive responses for cytochrome-c oxidase, catalase, reduction of nitrate and nitrite, β-galactosidase activity and hydrolysis of starch, xylan, peptone, Tween 40, Tween 80 and casein. Strain Corallo1T was found to be mesophilic, neutrophilic to alkalophilic and slightly halophilic. According to analysis of the almost-complete 16S rRNA gene, strain Corallo1T is closely related to Vibrio celticus (100% sequence similarity), Vibrio gigantis (100%), Vibrio crassostreae (99.7%), Vibrio artabrorum (99.7%) and Vibrio pomeroyi (99.6%). MLSA of five housekeeping genes (atpA, pyrH, recA, rpoA and rpoD) was performed to refine the phylogenetic relationships of strain Corallo1T. A draft genome sequence of strain Corallo1T was obtained. The DNA G+C content of this strain was determined to be 44.5 mol %. The major cellular fatty acids of strain Corallo1T are C16:1, n-C16:0 and C18:1, and the major isoprenoid ubiquinone is Q8. ANI indexes, in silico estimations of DDH values and wet lab DDH values demonstrated that strain Corallo1T represents an independent genomospecies. Based on a polyphasic taxonomic characterisation, strain Corallo1T is concluded to represent a novel species of the genus Vibrio, for which the name Vibrio coralliirubri sp. nov. is proposed. The type strain is Corallo1T (= DSM 27495T = CIP 110630T).

Matched MeSH terms: Bacterial Proteins/genetics
Molecular Characterization of Extended-Spectrum Beta Lactamase- and Carbapenemase-Producing Pseudomonas aeruginosa Strains from a Malaysian Tertiary Hospital

Phoon HYP, Hussin H, Hussain BM, Thong KL

Microb Drug Resist, 2018 Oct;24(8):1108-1116.
PMID: 29437541 DOI: 10.1089/mdr.2017.0258

Pseudomonas aeruginosa infections account for high morbidity and mortality rates worldwide. Increasing resistance toward β-lactams, especially carbapenems, poses a serious therapeutic challenge. However, the multilocus sequence typing (MLST) of extended-spectrum beta lactamase (ESBL)- and carbapenemase-producing clinical P. aeruginosa has not been reported in Malaysia. This study aimed to determine the antibiotic susceptibility profiles, resistance genes, pulsotypes, and sequence types (STs) of clinical P. aeruginosa from a Malaysian tertiary hospital. These characteristics were analyzed by disk diffusion, minimum inhibitory concentration, polymerase chain reaction, pulsed-field gel electrophoresis (PFGE), and MLST for 199 nonreplicate clinical strains. The susceptibility of the strains toward the carbapenems and piperacillin-tazobactam was the lowest (≤90%), while ≥90% of the strains remained susceptible to all other classes of antimicrobial agents tested. The multidrug-resistant strains displayed high level resistance to cephalosporins (48 to ≥256 mg/L) and carbapenems (4-32 mg/L). Eleven strains harbored class 1 integrons containing blaGES-13, blaVIM-2, blaVIM-6, blaOXA-10, aacA(6')-Ib, aacA(6')-II, aadA6, and gcuD gene cassettes. Extra-integron genes, blaGES-20, blaIMP-4, blaVIM-2, and blaVIM-11, were also found. Overall, the maximum likelihood tree showed concordance in the clustering of strains having the same STs and PFGE clusters. ST708 was the predominant antibiotic-susceptible clone detected from the neonatal intensive care unit. The STs 235, 809, and 1076 clonal clusters consisted of multidrug resistant strains. ST235 is a recognized international high-risk clone. This is the first report of blaGES-13 and blaGES-20 ESBL-encoding gene variants and novel STs (STs 2329, 2335, 2337, 2338, 2340, and 2341) of P. aeruginosa in Malaysia.

Matched MeSH terms: Bacterial Proteins/genetics*

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