ORCID Profile
0000-0001-5625-1317
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Griffith University
,
Menzies School of Health Research
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Publisher: American Society for Microbiology
Date: 30-05-2019
DOI: 10.1128/MRA.00009-19
Abstract: Aeromonas hydrophila and Aeromonas dhakensis are ubiquitous in marine and aquatic environments. Both species, which cause significant skin and soft tissue infection, are often associated with water activities and floods.
Publisher: Oxford University Press (OUP)
Date: 13-03-2008
DOI: 10.1093/JAC/DKN109
Publisher: Microbiology Society
Date: 08-2006
Abstract: Multidrug-resistant Escherichia coli (MDREC) expressing AmpC β -lactamases have emerged as a cause of opportunistic infections in dogs. Following a cluster of extraintestinal infections caused by two distinct clonal groups (CGs) of bla CMY -producing MDREC, a 12-month infection control study was undertaken at a veterinary teaching hospital in Brisbane, Australia. Swabs from the rectum of hospitalized dogs ( n =780), hospital staff ( n =16) and the hospital environment ( n =220) were plated onto selective agar to obtain multidrug-resistant (MDR) coliforms. These were then tested by multiplex PCR for E. coli uspA , bla CMY and the class 1 integron-associated dfrA17-aadA5 gene cassette for rapid identification of MDREC CG 1 (positive for all three genes) and CG 2 (positive for uspA and bla CMY only). A total of 16.5 % of the dog rectal swabs and 4.1 % of the hospital environmental swabs yielded MDREC, and on the basis of multiplex PCR, PFGE and plasmid profiling, these were confirmed to belong to either CG 1 or CG 2. Both CG 1 and CG 2 isolates were obtained from clinical cases of extraintestinal infection and rectal swabs from hospitalized dogs over the same period of time, whereas only CG 1 isolates were obtained from the hospital environment. Both CGs were prevalent during the first 6 months, but only CG 2 was isolated during the second 6 months of the study. Two isolates obtained from rectal swabs of staff working in the hospital belonged to CG 2, with one of the isolates possessing the same REDP as nine isolates from dogs, including six isolates associated with cases of extraintestinal infection. CG 1 isolates belonged to E. coli serotypes O162 : H−, OR : H− or Ont : H−, whereas CG 2 isolates belonged to O153 : HR, OR : HR or OR : H34. These results confirm that in this particular outbreak, canine MDREC were highly clonal and CG 2 MDREC may colonize both humans and dogs.
Publisher: Hindawi Limited
Date: 30-09-2022
DOI: 10.1155/2022/3191285
Abstract: Objective. SARS-CoV-2 infection may cause multiple organ failure. However, scarce information can be found on the impact on the endocrine system. This study was conducted to determine plasma Adrenocorticotropic hormone (ACTH) and plasma cortisol levels in a cohort of COVID-19 patients with Acute Respiratory Distress Syndrome (ARDS). Methods. A prospective cohort study was conducted on COVID-19 patients who manifested ARDS and were admitted to the ICU of Dr. Soetomo Tertiary Hospital, Surabaya, Indonesia. Morning plasma ACTH and plasma total cortisol were measured on 45 recruited patients. The outcome of the patient was justified based on the survivance on days 7th and 30th during the follow-up with groupings of surviving for survived patients and nonsurvive for deceased patients. Results. The ACTH and cortisol median were 1.06 (0.5–64.57) pg/mL and 17.61 (0.78–75) μg/dL, respectively. Both parameters were assembled to allow the allocation of the 45 subjects into the survive and nonsurvive groups. There was a moderate correlation between ACTH and cortisol levels in all groups ( r = 0.46 , p 0.002 ) and particularly ACTH and cortisol levels in COVID-19 patients who survived on the 7th-day and 30th-day follow-up ( r = 0.518 and r = 0.568 , respectively, with p 0.05 ). It is important to note that there was no correlation for an in idual parameter, either ACTH only or cortisol only, compared to the outcome among patients with various comorbid. Conclusion. ACTH or cortisol alone has no correlation to the outcome of these patients. Therefore, further study of the potential use of corticosteroid treatments guided by ACTH and cortisol levels in reducing the risk of ARDS warrants further investigation.
Publisher: American Society for Microbiology
Date: 13-04-2017
Abstract: Roseomonas mucosa is an opportunistic pathogen that causes infections in humans and is often associated with vascular catheter-related bacteremia. Here, we report the draft genome sequence of Roseomonas mucosa strain AU37, isolated from a peripheral intravenous catheter tip.
Publisher: Wiley
Date: 07-2008
DOI: 10.1111/J.1939-1676.2008.00124.X
Abstract: Extraintestinal infections caused by multidrug-resistant (MDR) Escherichia coli and Enterobacter are becoming more common in veterinary medicine. To generate hypotheses for risk factors for dogs acquiring extraintestinal infection caused by MDR E. coli and Enterobacter, describe antimicrobial resistance profiles and analyze treatment and clinical outcomes. Thirty-seven dogs diagnosed with extraintestinal infection caused by MDR E. coli and Enterobacter spp. between October 1999 and June 2006. Retrospective case series assembled from hospital records data, including clinical history before 1st MDR isolation and treatment outcome. Identity and antimicrobial susceptibility profiles were confirmed by standard microbiological techniques for 57 isolates. Most dogs had an underlying disease condition (97%), received prior antimicrobial treatment (87%), were hospitalized for >or =3 days (82%), and had a surgical intervention (57%). The urinary tract was the most common infection site (62%), and urinary catheterization, bladder stasis, or both were common among dogs (24%). Some dogs were treated with high doses of co-amoxyclavulanate (n = 14) and subsequently recovered even though the isolates showed in vitro resistance to this antimicrobial. Other dogs were successfully treated with chlor henicol (n = 11) and imipenem (n = 2). Predisposing disease condition, any prior antimicrobial use rather than a specific class of antimicrobial, duration of hospitalization, and type of surgical procedure might be risk factors for acquiring MDR extraintestinal infections. Whereas culture and sensitivity results can indicate use of last-resort antimicrobials such as imipenem for MDR infections, some affected dogs can recover after administration of high doses of co-amoxyclavulanate.
Publisher: Microbiology Society
Date: 03-2007
Abstract: The genetic determinants involved in reduced susceptibility to third-generation cephalosporins and aztreonam were identified in ten canine Enterobacter isolates associated with opportunistic infections in three veterinary hospitals in Brisbane, Australia. All isolates were evaluated by a combination of phenotypic (broth microdilution and disc susceptibility, modified disc diffusion and IEF) and genotypic (PFGE, plasmid analysis, Southern blot hybridization, bacterial conjugation, PCR and sequencing) methods to investigate genetic relatedness and to identify plasmid-mediated resistance genes, in particular beta-lactamase genes responsible for extended-spectrum cephalosporin resistance. The ten canine isolates were genotypically erse based on PFGE and belonged to either Enterobacter cloacae or Enterobacter hormaechei on the basis of 16S rRNA gene sequence analysis. Plasmid profiles were also erse. Nine isolates contained a transmissible blaSHV-12-carrying plasmid (approximately 140 kb) that also conferred resistance to chlor henicol, gentamicin, spectinomycin, tetracycline, trimethoprim and sulfonamides. In all plasmid-mediated extended-spectrum beta-lactamase (ESBL)-producing isolates including transconjugants, blaSHV-12 was shown to reside in a approximately 6.5 kb plasmid fragment. The remaining isolate that was not an ESBL producer possessed an AmpC beta-lactamase gene (blaCMY-2) on a approximately 93 kb transmissible plasmid. This plasmid did not contain any other antimicrobial resistance genes. Additional plasmid-mediated beta-lactamases identified in some isolates included bla(TEM) and blaOXA-10. This is the first report of canine Enterobacter isolates containing transmissible plasmid-mediated blaSHV-12 and blaCMY-2 resistance genes. Therefore, Enterobacter isolated from opportunistic infections in dogs may be an important reservoir of plasmid-mediated resistance genes, which could potentially be spread to other members of the Enterobacteriaceae.
Publisher: Microbiology Society
Date: 04-2017
DOI: 10.1099/JMM.0.000463
Abstract: Dressings containing chlorhexidine gluconate (CHG) are increasingly used in clinical environments for prevention of infection at central venous catheter insertion sites. Increased tolerance to this biocide in staphylococci is primarily associated with the presence of qacA/B and smr genes. We used a culture-independent method to assess the prevalence of these genes in 78 DNA specimens recovered from the skin of 43 patients at catheter insertion sites in the arm that were covered with CHG dressings. Of the 78 DNA specimens analysed, 52 (67 %) possessed qacA/B and 14 (18 %) possessed smr all s les positive for smr were also positive for qacA/B. These prevalence rates were not statistically greater than those observed in a subs le of specimens taken from non-CHG treated contralateral arms and non-CHG-dressing exposed arms. A statistically greater proportion of specimens with greater than 72 h exposure to CHG dressings were qac-positive (P=0.04), suggesting that the patients were contaminated with bacteria or DNA containing qacA/B during their hospital stay. The presence of qac genes was not positively associated with the presence of DNA specific for Staphylococcusepidermidis and Staphylococcusaureus in these specimens. Our results show that CHG genes are highly prevalent on hospital patients' skin, even in the absence of viable bacteria.
Publisher: American Society for Microbiology
Date: 11-2009
DOI: 10.1128/AAC.00533-09
Abstract: A combination of phenotypic and genotypic methods was used to investigate 70 unique Escherichia coli clinical isolates identified as producing extended-spectrum β-lactamases (ESBLs) at a medical center in Pittsburgh, PA, between 2007 and 2008. Fifty-seven isolates (81%) produced CTX-M-type ESBLs, among which CTX-M-15 was predominant ( n = 46). Isolates producing CTX-M-2, -9, -14, and -65 were also identified. One CTX-M-producing isolate coproduced CMY-2 cephalosporinase. Ten isolates (14%) produced SHV-type ESBLs, either SHV-5 or SHV-7. Two isolates produced only CMY-2 or -32. Pulsed-field gel electrophoresis revealed the presence of two major clusters of CTX-M-15-producing E. coli isolates, one in phylotype B2 ( n = 15) and the other in phylotype A ( n = 19). Of four phylotype B2 isolates that were able to transfer the bla CTX-M-15 -carrying plasmids, three showed fingerprints related ( %) to those of plasmids from phylotype A isolates. In phylotype B2, all CTX-M-15-producing isolates, as well as three isolates producing CTX-M-14, two producing SHV-5, and one producing SHV-7, belonged to the international epidemic clone defined by serotype O25:H4 and sequence type 131. The plasmids from eight of nine CTX-M-15-producing E. coli isolates of phylotype A that were examined were highly related to each other and were also found in two isolates belonging to phylotype D, suggesting horizontal transfer of this bla CTX-M-15 -carrying plasmid between phylotypes. Our findings underscore the need to further investigate the epidemiology and virulence of CTX-M-producing E. coli in the United States.
Publisher: American Society for Microbiology
Date: 02-2018
DOI: 10.1128/AAC.02280-17
Abstract: Carbapenem-resistant Enterobacteriaceae are urgent threats to global human health. These organisms produce β-lactamases with carbapenemase activity, such as the metallo-β-lactamase NDM-1, which is notable due to its association with mobile genetic elements and the lack of a clinically useful inhibitor. Here we examined the ability of copper to inhibit the activity of NDM-1 and explored the potential of a copper coordination complex as a mechanism to efficiently deliver copper as an adjuvant in clinical therapeutics. An NDM-positive Escherichia coli isolate, MS6192, was cultured from the urine of a patient with a urinary tract infection. MS6192 was resistant to antibiotics from multiple classes, including erse β-lactams (penicillins, cephalosporins, and carbapenems), aminoglycosides, and fluoroquinolones. In the presence of copper (range, 0 to 2 mM), however, the susceptibility of MS6192 to the carbapenems ertapenem and meropenem increased markedly. In standard checkerboard assays, copper decreased the MICs of ertapenem and meropenem against MS6192 in a dose-dependent manner, suggesting a synergistic mode of action. To examine the inhibitory effect of copper in the absence of other β-lactamases, the bla NDM-1 gene from MS6192 was cloned and expressed in a recombinant E. coli K-12 strain. Analysis of cell extracts prepared from this strain revealed that copper directly inhibited NDM-1 activity, which was confirmed using purified recombinant NDM-1. Finally, delivery of copper at a low concentration of 10 μM by using the FDA-approved coordination complex copper-pyrithione sensitized MS6192 to ertapenem and meropenem in a synergistic manner. Overall, this work demonstrates the potential use of copper coordination complexes as novel carbapenemase adjuvants.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2020
DOI: 10.1038/S41467-019-14139-5
Abstract: 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 bla IMP-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 bla IMP-4 gene on a large IncHI2 plasmid carried by all IMP-4-producing strains across different hospitals. Shotgun metagenomic sequencing of environmental s les 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.
Publisher: Hindawi Limited
Date: 27-05-2022
DOI: 10.1155/2022/9555121
Abstract: Background. Rapid and reliable tests are essential for the diagnostic laboratory confirmation of urinary tract infections (UTIs). Until now, UTI has been confirmed by the microbiology culture of urine, requiring at least 48-hour turnaround time (TAT), with a standardized microscopic method being widely favored. Automated urine flow cytometry, however, has recently been used to improve the rapid TAT by analyzing the urine sediment. This study therefore aimed to compare the diagnostic value of the Shih-Yung conventional microscopic and urine flow cytometry methods in the detection of leukocyte and bacterial parameters of patients with UTIs in an outpatient clinic. Methods. A cross-sectional study was conducted on a total of 100 patients. Seventy urine s les were positive for leukocytes and nitrite chemistry, and 30 were negative for both. The measurements of urine leukocytes and bacteria were compared between Sysmex UF-5000 urine flow cytometry and the Shih-Yung method. The diagnostic value was obtained from ROC analysis of urine flow cytometry and the culture. Results. A leukocyte cutoff value of 87.2/μL had a sensitivity and specificity of 98.33% and 95%, respectively, and 98.33% sensitivity and 75% specificity at a bacterial cutoff of 582.22/μL. Interestingly, our study identified strong and consistent agreement of leukocyte and bacterial parameters between urine flow cytometry and Shih-Yung (k = 0.959, p 0.001 and k = 0.939, p 0.001 , respectively). Furthermore, through analyzing the dominance angle of the scattergram, a strong agreement was obtained with the culture result (k = 0.880, p 0.001 ). Conclusions. The Shih-Yung method showed consistent agreement with urine flow cytometry for the detection of leukocytes and bacteria. The use of certain cutoffs for bacterial and leukocyte parameters in urine flow cytometry demonstrated very good performance in detecting acquired symptomatic UTIs.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.VETMIC.2009.11.031
Abstract: Fluoroquinolone resistance is becoming more common in veterinary medicine. Resistance is due to a combination of chromosomal and plasmid-mediated fluoroquinolone resistance (PMQR) mechanisms. The aim of the present study was to screen 17 multidrug-resistant Enterobacter isolates obtained from opportunistic infections in companion animals for chromosomal and plasmid-mediated fluoroquinolone resistance determinants and to determine if they are co-located with other antimicrobial resistance genes including beta-lactamases. Phenotypic tests (biochemical identification, organic solvent tolerance testing) were combined with genotypic analysis (PCR, pulsed field gel electrophoresis, sequencing, plasmid isolation and southern blot hybridization) to characterize the molecular basis for fluoroquinolone resistance. Antimicrobial susceptibility was determined by broth microdilution for fluoroquinolone antimicrobials (enrofloxacin, ciprofloxacin, moxifloxacin, marbofloxacin and pradofloxacin) and by disk diffusion for other antimicrobials. Sixteen isolates were resistant to at least one of the five fluoroquinolones tested. Fourteen isolates possessed PMQR determinants which were identified as qnrA1 (n=3) or qnrB2 (n=11), often in combination with aac(6')-1b-cr (n=6). The PMQR genes were localized to large, transferable MDR plasmids often associated with an extended-spectrum beta-lactamase and quinolone resistance was co-transferred with bla(SHV-12) for 10 of the 14 qnr-positive strains. Three isolates had wild-type topoisomerases, 11 had a single point mutation in gyrA (Ser83Phe or Tyr), and three had two mutations one in gyrA (Ser83Ile) and one in parC (Ser80Ile). PMQR genes in clinical veterinary Enterobacter isolates are co-located with beta-lactamases and other resistance genes on large transferable plasmids. PMQR genes contribute to fluoroquinolone resistance when combined with topoisomerase mutations and efflux.
Publisher: Institution of Engineering and Technology (IET)
Date: 02-06-2023
DOI: 10.1049/GTD2.12855
Abstract: The access of large‐scale distributed generation (DG) easily leads to energy imbalance in distribution network. To deal with this issue, this paper proposes an energy optimal schedule method for distribution network considering the participation of source‐load‐storage aggregation groups (SAGs). Firstly, the system model consisting of distribution network layer and SAGs layer is established, and the schedule objectives and constraints of each layer are also given. Secondly, considering the fluctuation on the load side, a forecasting method based on Adaboost integrated convolutional neural networks and bidirectional long‐short term memory is proposed. Then, the improved sparrow search algorithm (ISSA) is proposed by using the tent map and Levy flight on the original sparrow search algorithm. At the same time, by introducing Pareto dominance relation and adaptive grid algorithm, the multi‐objective sparrow search algorithm (MOSSA) is derived. After that, a two‐layer optimization framework (ISSA–MOSSA) is proposed to solve the studied system. The simulation results verify the accuracy of the proposed load forecasting model, the superiority of ISSA as well as MOSSA, and the effectiveness of ISSA–MOSSA in solving the energy optimal schedule problem of the distribution system with the access of DG.
Publisher: American Society for Microbiology
Date: 30-04-2015
Abstract: We report here the draft genome sequence of uropathogenic Escherichia coli sequence type 648 (ST648) possessing bla NDM-5 from a 55-year-old female in Australia with a history of travel to India. The plasmid-mediated bla NDM-5 was in a genetic context nearly identical to that of the GenBank entry of an IncX3 bla NDM-5 plasmid previously reported from India ( Klebsiella pneumoniae MGR-K194).
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.MICINF.2008.10.014
Abstract: The study established the virulence potential of multidrug-resistant Escherichia coli (MDREC) isolates from nosocomial infections in hospitalised dogs. The isolates were resistant to fluoroquinolones, belonged to two distinct clonal groups (CG1 and CG2) and contained a plasmid-mediated AmpC (CMY-7) beta-lactamase. CG1 isolates (n=14) possessed two of 36 assayed extraintestinal virulence genes (iutA and traT) and belonged to phylogenetic group A, whereas CG2 isolates (n=19) contained four such genes (iutA, ibeA, fimH and kpsMT K5) and belonged to group D. In a mouse gastrointestinal tract colonisation model, colonisation by index CG1 strain C1 was transient, in contrast to the index CG2 strain C2b, which persisted up to 40days post-inoculation. In a mouse subcutaneous challenge model, both strains were less virulent than archetypal group B2 extraintestinal pathogenic E. coli (ExPEC) strain CFT073 strain C1 caused no systemic signs and strain C2b was lethal to only one of six mice. In a mouse urinary tract infection model, strain C2b colonised the mouse bladder over 2 logs higher compared to strain C1. Whilst both groups of canine MDREC appear less virulent than a reference human ExPEC strain, CG2 strains have greater capacity for colonisation and virulence.
Publisher: Oxford University Press (OUP)
Date: 15-03-2009
DOI: 10.1086/597037
Publisher: American Society for Microbiology
Date: 25-02-2016
Abstract: We report the draft genome sequence of the oral commensal Streptococcus oralis 89a isolated from the throat of a healthy child during a streptococcal tonsillitis outbreak in Umeå, Sweden. S. oralis 89a was known to have interference activity against respiratory pathogens in which the colicin V was the potential bacteriocin-encoding gene.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.JINORGBIO.2016.11.028
Abstract: Alternative solutions need to be developed to overcome the growing problem of multi-drug resistant bacteria. This study explored the possibility of creating complexes of antibiotics with metal ions, thereby increasing their activity. Analytical techniques such as isothermal titration calorimetry and nuclear magnetic resonance were used to examine the structure and interactions between Cu(II), Ag(I) or Zn(II) and β-lactam antibiotics. The metal-β-lactam complexes were also tested for antimicrobial activity, by micro-broth dilution and disk diffusion methods, showing a synergistic increase in the activity of the drugs, and enzymatic inhibition assays confirming inhibition of β-lactamases responsible for resistance. The metal-antibiotic complex concept was proven to be successful with the activity of the drugs enhanced against β-lactamase-producing bacteria. The highest synergistic effects were observed for complexes formed with Ag(I).
Publisher: Microbiology Society
Date: 06-2018
DOI: 10.1099/JMM.0.000730
Abstract: The molecular epidemiology and resistance mechanisms of carbapenem-resistant Pseudomonas aeruginosa (CRPA) were determined in hospitals in the countries of the Gulf Cooperation Council (GCC), namely, Saudi Arabia, the United Arab Emirates, Oman, Qatar, Bahrain and Kuwait. Isolates were screened for common carbapenem-resistance genes by PCR. Relatedness between isolates was assessed using previously described genotyping methods: an informative-single nucleotide polymorphism MassARRAY iPLEX assay (iPLEX20SNP) and the enterobacterial repetitive intergenic consensus (ERIC)-PCR assay, with selected isolates being subjected to multilocus sequence typing (MLST). Ninety-five non-repetitive isolates that were found to be resistant to carbapenems were subjected to further investigation.Results/Key findings. The most prevalent carbapenemase-encoding gene, blaVIM-type, was found in 37/95 (39 %) isolates, while only 1 isolate (from UAE) was found to have blaIMP-type. None of the CRPA were found to have blaNDM-type or blaKPC-type. We found a total of 14 sequence type (ST) clusters, with 4 of these clusters being observed in more than 1 country. Several clusters belonged to the previously recognized internationally disseminated high-risk clones ST357, ST235, ST111, ST233 and ST654. We also found the less predominant ST316, ST308 and ST823 clones, and novel MLST types (ST2010, ST2011, ST2012 and ST2013), in our collection. Overall our data show that 'high-risk' CRPA clones are now detected in the region and highlight the need for strategies to limit further spread of such organisms, including enhanced surveillance, infection control precautions and further promotion of antibiotic stewardship programmes.
Publisher: Springer Science and Business Media LLC
Date: 02-01-2018
DOI: 10.1038/S41467-017-02123-W
Abstract: The public health threat posed by a looming ‘post-antibiotic’ era necessitates new approaches to antibiotic discovery. Drug development has typically avoided exploitation of membrane-binding properties, in contrast to nature’s control of biological pathways via modulation of membrane-associated proteins and membrane lipid composition. Here, we describe the rejuvenation of the glycopeptide antibiotic vancomycin via selective targeting of bacterial membranes. Peptide libraries based on positively charged electrostatic effector sequences are ligated to N -terminal lipophilic membrane-insertive elements and then conjugated to vancomycin. These modified lipoglycopeptides, the ‘vancapticins’, possess enhanced membrane affinity and activity against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive bacteria, and retain activity against glycopeptide-resistant strains. Optimised antibiotics show in vivo efficacy in multiple models of bacterial infection. This membrane-targeting strategy has potential to ‘revitalise’ antibiotics that have lost effectiveness against recalcitrant bacteria, or enhance the activity of other intravenous-administered drugs that target membrane-associated receptors.
Publisher: Oxford University Press (OUP)
Date: 12-2009
DOI: 10.1086/648077
Abstract: Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae, Escherichia coli, and Serratia marcescens were sequentially identified in a patient who underwent small bowel transplantation. Molecular typing and plasmid analysis suggested that the KPC gene was acquired by E. coli, most likely from K. pneumoniae, and was subsequently transferred to S. marcescens.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.EJMECH.2017.05.061
Abstract: A SAR study on derivatives of 2-amino-1-benzyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile 5a revealed that the 3-carbonitrile group, vicinal 4,5-diphenyl and N-benzyl side chains of the pyrrole are important for the inhibitory potencies of these compounds against members representing the three main subclasses of metallo-β-lactamases (MBLs), i.e. IMP-1 (representing the B1 subgroup), CphA (B2) and AIM-1 (B3). Coupling of 5a with a series of acyl chlorides and anhydrides led to the discovery of two N-acylamide derivatives, 10 and 11, as the two most potent IMP-1 inhibitors in this series. However, these compounds are less effective towards CphA and AIM-1. The N-benzoyl derivative of 5a retained potent in vitro activity against each of MBLs tested (with inhibition constants in the low μM range). Importantly, this compound also significantly enhanced the sensitivity of IMP-1, CphA- or AIM-1-producing cell cultures towards meropenem. This compound presents a promising starting point for the development of a universal MBL inhibitor, targeting members of each of the major subgroups of this family of enzymes.
Publisher: American Society for Microbiology
Date: 11-2008
DOI: 10.1128/AAC.00570-08
Abstract: A total of 49 unique clinical isolates of multidrug-resistant (MDR) Acinetobacter baumannii identified at a tertiary medical center in Pittsburgh, Pennsylvania, between August 2006 and September 2007 were studied for the genetic basis of their MDR phenotype. Approximately half of all A. baumannii clinical isolates identified during this period qualified as MDR, defined by nonsusceptibility to three or more of the antimicrobials routinely tested in the clinical microbiology laboratory. Among the MDR isolates, 18.4% were resistant to imipenem. The frequencies of resistance to amikacin and ciprofloxacin were high at 36.7% and 95.9%, respectively. None of the isolates was resistant to colistin or tigecycline. The presence of the carbapenemase gene bla OXA-23 and the 16S rRNA methylase gene armA predicted high-level resistance to imipenem and amikacin, respectively. bla OXA-23 was preceded by insertion sequence IS Aba1 , which likely provided a potent promoter activity for the expression of the carbapenemase gene. The structure of the transposon defined by IS Aba1 differed from those reported in Europe, suggesting that IS Aba1 -mediated acquisition of bla OXA-23 may occur as an independent event. Typical substitutions in the quinolone resistance-determining regions of the gyrA and parC genes were observed in the ciprofloxacin-resistant isolates. Plasmid-mediated quinolone resistance genes, including the qnr genes, were not identified. Fifty-nine percent of the MDR isolates belonged to a single clonal group over the course of the study period, as demonstrated by pulsed-field gel electrophoresis.
Publisher: American Society for Microbiology
Date: 06-2009
DOI: 10.1128/AAC.00290-09
Publisher: Oxford University Press (OUP)
Date: 08-03-2006
DOI: 10.1093/JAC/DKL057
Abstract: To determine clonality and identify plasmid-mediated resistance genes in 11 multidrug-resistant Escherichia coli (MDREC) isolates associated with opportunistic infections in hospitalized dogs in Australia. Phenotypic (MIC determinations, modified double-disc diffusion and isoelectric focusing) and genotypic methods (PFGE, plasmid analysis, PCR, sequencing, Southern hybridization, bacterial conjugation and transformation) were used to characterize, investigate the genetic relatedness of, and identify selected plasmid-mediated antimicrobial resistance genes, in the canine MDREC. Canine MDRECs were ided into two clonal groups (CG 1 and 2) with distinct restriction endonuclease digestion and plasmid profiles. All isolates possessed bla(CMY-7) on an approximately 93 kb plasmid. In CG 1 isolates, bla(TEM), catA1 and class 1 integron-associated dfrA17-aadA5 genes were located on an approximately 170 kb plasmid. In CG 2 isolates, a second approximately 93 kb plasmid contained bla(TEM) and unidentified class 1 integron genes, although a single CG 2 strain carried dfrA5. Antimicrobial susceptibility profiling of E. coli K12 transformed with CG 2 large plasmids confirmed that the bla(CMY-7)-carrying plasmid did not carry any other antimicrobial resistance genes, whereas the bla(TEM)/class 1 integron-carrying plasmid carried genes conferring resistance to tetracycline and streptomycin also. This is the first report on the detection of plasmid-mediated bla(CMY-7) in animal isolates in Australia. MDREC isolated from extraintestinal infections in dogs may be an important reservoir of plasmid-mediated resistance genes.
Publisher: American Society for Microbiology
Date: 27-08-2015
Abstract: We report the draft genome sequences of two unrelated cases of Escherichia coli sequence type 131 (ST131) possessing the carbapenemase gene bla IMP-4 . The E. coli ST131 SN5 isolate also possessed bla SHV-12 and plasmid-mediated quinolone-resistance genes. Wider dissemination of bla IMP-4 may occur due to the bla IMP-4 -carrying L/M or HI2 plasmids among E. coli ST131 isolates.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.MIMET.2016.10.005
Abstract: It has been described that the sensitivity of the Carba NP test may be low in the case of OXA-48-like carbapenamases and mass spectrometry based methods as well as a colorimetry based method have been described as alternatives. We evaluated 84 Enterobacteriaceae isolates including 31 OXA-48-like producing isolates and 13 isolates that produced either an imipenemase (IMP n=8), New Delhi metallo-β-lactamase (NDM n=3), or Klebsiella pneumoniae carbapenemase (KPC n=2), as well as 40 carbapenemase negative Enterobacteriaceae isolates. We used the Neo-Rapid CARB kit, assessing the results with the unaided eye and compared it with a colorimetric approach. Furthermore, we incubated the isolates in growth media with meropenem and measured the remaining meropenem after one and 2h of incubation, respectively, using liquid chromatography tandem mass spectrometry (LC-MS/MS). Whilst all carbapenemase producing isolates with the exception of the OXA-244 producer tested positive for both the Neo-rapid CARB test using the unaided eye or colorimetry, and the 13 isolates producing either IMP, NDM or KPC hydrolysed the meropenem in the media almost completely after 2h of incubation, the 31 OXA-48-like producing isolates exhibited very variable hydrolytic activity when incubated in growth media with meropenem. In our study, the Neo-Rapid CARB test yielded a sensitivity of 98% for both the traditional and the colorimetric approach with a specificity of 95% and 100% respectively. Our results indicate that the Neo-Rapid CARB test may have use for the detection of OXA-48 type carbapenemases and that it may be particularly important to ensure bacterial lysis for the detection of these weaker hydrolysers.
Publisher: American Society for Microbiology
Date: 29-10-2015
Abstract: Here, we report the draft genome sequences of Burkholderia pseudomallei and Staphylococcus aureus causing chronic rhinosinusitis. Whole-genome sequencing determined the B. pseudomallei as sequence type (ST) 1381 and the S. aureus as ST8. B. pseudomallei possessed the bla OXA-59 gene. This study illustrates the potential emergence of B. pseudomallei in cases of chronic rhinosinusitis.
Publisher: American Society for Microbiology
Date: 12-2008
DOI: 10.1128/JCM.01408-08
Abstract: A disk potentiation method using carbapenems as substrates and 3-aminophenyl boronic acid as an inhibitor was evaluated for the detection of Klebsiella pneumoniae carbapenemase (KPC)-type β-lactamases. When combined with nonsusceptibility to ertapenem, the method was easy to perform and reliably differentiated isolates producing KPC-type β-lactamases from those producing other types of β-lactamases.
Publisher: American Society for Microbiology
Date: 11-2010
DOI: 10.1128/JCM.01208-10
Abstract: Multidrug-resistant Acinetobacter baumannii is a worldwide nosocomial menace. We sought to better understand its behavior through studying the molecular epidemiology of this organism at the Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia, over a 10-year period. Multilocus sequence typing (MLST), semiautomated repetitive sequence-based PCR (rep-PCR), and pulsed-field gel electrophoresis (PFGE) were performed on a selection of 31 A. baumannii isolates collected over the 10-year period to determine their relationships to one another. MLST also allowed us to put this information in a global context. The presence or absence of bla OXA-23 was also established. The presence of bla OXA-23 closely correlated with carbapenem resistance in our collection. Sequence type 92 (ST92) was the dominant sequence type and was present in the hospital for 9 years. There was also evidence of the spread of ST69, ST73, and ST125 (novel) within the hospital, but this was not sustained over long periods. There were only single ex les of the novel sequence types ST126 and ST127. The different typing methods clustered the isolates similarly however, PFGE and rep-PCR were more discriminatory than MLST. Worldwide, ST92 and the associated clonal complex 92 represent the most s led and widespread sequence type(s) and are also known as European clone 2 and worldwide clonal lineage 2. Antibiotic susceptibility within ST92 is variable, suggesting a role for mechanisms other than antibiotic resistance in its success.
Publisher: Cambridge University Press (CUP)
Date: 07-2016
DOI: 10.1017/S0022215116008276
Abstract: Melioidosis is a serious infection caused by soil-dwelling Gram-negative bacillus Burkholderia pseudomallei . It is most commonly reported in Northern Australia, Southeast and Southern Asia, China, and Taiwan. A case report and short review of the literature are presented. Presentation, diagnosis including genomic sequencing, and acute and long-term management are discussed. A 58-year-old female presented with chronic rhinosinusitis secondary to melioidosis. This is the third reported incidence of sinusitis secondary to melioidosis, which occurred in an otherwise well female with no risk factors and no apparent cause of exposure. Treatment involved an acute phase in which meropenem was administered parenterally for two weeks, followed by a prolonged oral course of trimethoprim-sulfamethoxazole for three months, as per recommended guidelines. In patients presenting with refractory chronic rhinosinusitis, ENT surgeons should consider the presence of unusual causative pathogens such as B pseudomallei , particularly in those with recent travel history to Northern Queensland and/or Southeast Asia.
Publisher: Springer Science and Business Media LLC
Date: 03-2018
DOI: 10.1038/S41598-018-21984-9
Abstract: Antibiotic resistance associated with the clinically significant carbapenemases KPC, NDM and OXA-48 in Enterobacteriaceae is emerging as worldwide. In Australia, IMP-producing Enterobacteriaceae are the most prevalent carbapenemase-producing Enterobacteriaceae (CPE). Genomic characteristics of such CPE are well described, but the corresponding proteome is poorly characterised. We have thus developed a method to analyse dynamic changes in the proteome of CPE under antibiotic pressure. Specifically, we have investigated the effect of meropenem at sub-lethal concentrations to develop a better understanding of how antibiotic pressure leads to resistance. Escherichia coli strains producing either NDM-, IMP- or KPC-type carbapenemases were included in this study, and their proteomes were analysed in growth conditions with or without meropenem. The most significant difference in the bacterial proteomes upon the addition of meropenem was triggered amongst NDM-producers and to a lower extent amongst KPC-producers. In particular, HU DNA-binding proteins, the GroEL/GroES chaperonin complex and GrpE proteins were overexpressed. These proteins may thus contribute to the better adaptability of NDM- and KPC-producers to meropenem. A significant meropenem-induced increase in the expression of the outer membrane protein A was only observed in IMP-producers, thus demonstrating that carbapenemase-mediated resistance relies on far more complex mechanisms than simple inactivation of the antibiotic.
Publisher: American Society for Microbiology
Date: 07-2009
DOI: 10.1128/AAC.00133-09
Abstract: Here we describe three Escherichia coli clinical isolates with reduced susceptibility to cefepime. Sequencing of the bla CMY genes revealed two novel variants (CMY-33 and -44) with two- to four-amino-acid deletions in the H-10 helix. The deletions were responsible for 12- to 24-fold increases in the MICs of cefepime.
No related grants have been discovered for Hanna Sidjabat.