Oral health status and behaviours of preschool children in Hong Kong.

published_or_final_versio

Simple color tuning of phosphorescent dendrimer light emitting diodes

Published versio

Prevalence and characterization of hybrid blaCTX-M among Escherichia coli isolates from livestock and other animals

This study investigated 248 extended-spectrum β-lactamase-producing Escherichia coli isolates from 2012 to 2013 for hybrid blaCTX-M genes. blaCTX-M genes were detected in 228 isolates of which 14 isolates were hybrid blaCTX-M positive (6 blaCTX-M-123, 6 blaCTX-M-64, and 2 blaCTX-M-132). The 14 hybrid blaCTX-M–carrying isolates (8 from chickens, 2 each from pigs and cattle, 1 each from dog and rodent) were genetically diverse. All but 2 hybrid blaCTX-M were carried on IncI1 (5 blaCTX-M-123) and IncI2 (6 blaCTX-M-64 and one blaCTX-M-132) plasmids. Our IncI1 and IncI2 plasmids had pHNAH4-1–like and pHN1122-1–like restriction fragment length polymorphism patterns, respectively. Genetic relatedness of the plasmids to pHNAH4-1 and pHN1122-1 were confirmed by complete sequencing of 3 plasmids, pCTXM123_C0996, pCTXM64_C0967, and pCTXM132_P0421. Plasmids closely related to pHNAH4-1 and pHN1122-1 and carrying different blaCTX-M alleles have been reported from multiple geographic areas in China previously. The findings highlighted the wide dissemination of hybrid blaCTX-M variants in different parts of China.postprin

Plasmid-mediated fosfomycin resistance in Escherichia coli isolated from pig.

Previous studies have reported plasmid-mediated fosA3 among Escherichia coli originating from human and companion animals. In this study, the plasmid, designated pHK23a originating from a multidrug-resistant E. coli isolate recovered from a slaughter pig in December 2008 in Hong Kong, China was sequenced. In conjugation, the plasmid readily transferred to E. coli J53 at high frequencies. It belongs to the narrow host range IncFII incompatibility group and is 73,607bp in length. Sequence alignment showed that pHK23a has a 59.1kb backbone which shares high homology with the prototype R100 plasmid and a 14.5kb variable region. The variable region includes three genes mediating antimicrobial resistance (fosA3, ΔblaTEM-1, blaCTX-M-3), ten mobile genetic elements (four copies of IS26, insA, ΔinsB, ΔTn2, IS1, ΔISEcp1, Δintl1), the tir transfer inhibition protein, the pemI/pemK addiction system and eight ORFs of unknown functions (orf1, orf2, Δorf3, orf20, orf23, orf24, ycdA and ycdB). The three resistance genes were organized in a novel IS26-composite transposon-like structure. In conclusion, this is the first report of fosA3 containing plasmid in an isolate of pig origin. Since IncFII plasmids spread efficiently in Enterobacteriaceae, the detection of fosA3 with blaCTX-M is worrisome and might become a public health concern. © 2012 Elsevier B.V..postprin

Molecular Characterization of an Atypical IncX3 Plasmid pKPC-NY79 Carrying blaKPC-2 in a Klebsiella pneumoniae

The IncX family of plasmids has recently been expanded to include at least four subtypes, IncX1-IncX4. The revised classification provides an opportunity for improving our understanding of the sequence diversity of the IncX plasmids and the resistance genes they carried. We described the complete nucleotide sequence of a novel IncX3 plasmid, pKPC-NY79 (42,447 bp) from a sequence-type 258 Klebsiella pneumoniae strain that was isolated from a patient who was hospitalized in New York, United States. In pKPC-NY79, the plasmid scaffold and genetic load region were highly similar to homologous regions in pIncX-SHV (IncX3, JN247852) and the bla KPC carrying pKpQIL (IncFII k, GU595196), respectively, indicating that it has possibly arisen through recombination of plasmids. The bla KPC-2 gene, as part of a transposon Tn4401a, was found within the genetic load region. The backbone of pKPC-NY79 differs from pIncX-SHV by a deletion involving the gene tandem hns-topB (encoding H-NS protein and topoisomerase III, respectively) and a putative ATPase gene. Unexpectedly, the impact of the hns-topB deletion on host fitness and plasmid stability was found to be small. In conclusion, the findings contribute to a better understanding of the plasmid platforms carrying bla KPC and of variations in the backbone of the IncX3 plasmids. © 2013 Springer Science+Business Media New York.postprin

Carriage niches and molecular epidemiology of Staphylococcus lugdunensis and methicillin-resistant S. lugdunensis among patients undergoing long-term renal replacement therapy

We collected nasal, axilla, and groin swabs from 252 adult patients from 2 nephrology centers in Hong Kong. Staphylococcus lugdunensis carriage was detected in 51.6% patients (groin, 39.3%; axilla, 19.8%; nose, 17.9%). The carriage rates of methicillin-sensitive S. lugdunensis and methicillin-resistant S. lugdunensis (MRSL) were 46.0% and 8.3%, respectively. Independent risk factors for S. lugdunensis carriage included male sex (odds ratio [OR], 4.4), hemodialysis (OR, 2.2), and aged 18–50 years (OR, 2.4). The isolates belonged to 10 pulsotype clusters (n = 129) and 8 singletons (n = 8). All MRSL and most gentamicin- and tetracycline-resistant strains were found in a predominating sequence type 3 clone, designated HKU1, which accounted for 51.8% of all colonizing S. lugdunensis strains. The 21 MRSL isolates had SCCmec type V (n = 18), type IV (n = 2), and type I (n = 1). The finding highlights the potential for dissemination of multidrug resistance through successful S. lugdunensis clones.postprin

Identification and characterization of a novel incompatibility group X3 plasmid carrying blaNDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China

postprin

Decolonization of gastrointestinal carriage of vancomycin-resistant Enterococcus faecium: case series and review of literature

Background: Prolonged asymptomatic carriage of vancomycin-resistant enterococci (VRE) in the gastrointestinal tract and the lack of effective decolonization regimen perpetuate the endemicity of VRE in the healthcare settings.Case presentation: We report a regimen for decolonization of gastrointestinal carriage of VRE by a combination of environmental disinfection, patient isolation, bowel preparation to wash-out the fecal bacterial population using polyethylene glycol, a five-day course of oral absorbable linezolid and non-absorbable daptomycin to suppress any remaining VRE, and subsequent oral Lactobacillus rhamnosus GG to maintain the colonization resistance in four patients, including two patients with end-stage liver cirrhosis, one patient with complication post liver transplant, and one patient with complicated infective endocarditis. All patients had clearance of VRE immediately after decolonization, and 3 of them remained VRE-free for 23 to 137 days of hospitalization, despite subsequent use of intravenous broad-spectrum antibiotics without anti-VRE activity.Conclusion: This strategy should be further studied in settings of low VRE endemicity with limited isolation facilities. © 2014 Cheng et al.; licensee BioMed Central Ltd.published_or_final_versio

Predominance of pHK01-like incompatibility group FII plasmids encoding CTX-M-14 among extended-spectrum beta-lactamase-producing Escherichia coli in Hong Kong, 1996-2008

This study assessed the temporal changes in the molecular epidemiology of bacteremic Escherichia coli isolates producing CTX-M-14 in Hong Kong. Blood isolates from 1996 to 1998 (period 1, n = 50) and 2007 to 2008 (period 2, n = 117) were investigated by molecular methods. CTX-M-type ESBL was carried by 98.2% (164/167) of the isolates. In both periods, the CTX-M-9 group and CTX-M-14 allele were the predominant ESBL type. The major clones were found to change from ST68 and ST405 in period 1 to ST131, ST69, and ST12 in period 2. Among 65 CTX-M-14-producing plasmids investigated further, 54 had the FII replicon. Replicon sequence typing and plasmid polymerase chain reaction-restriction fragment length polymorphism showed that 79.6% (43/54) of the FII plasmid subset was similar to the completely sequenced plasmid, pHK01 (human urine, Hong Kong, 2004). These pHK01-like plasmids were found to have spread to the major clones (ST68, ST405, and ST131) and multiple singleton isolates of all 4 phylogenetic groups. © 2012 Elsevier Inc.postprin

High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients

Previous work on the subclones within Escherichia coli ST131 predominantly involved isolates from Western countries. This study assessed the prevalence and antimicrobial resistance attributed to this clonal group. A total of 340 consecutive, non-duplicated urinary E. coli isolates originating from four clinical laboratories in Hong Kong in 2013 were tested. ST131 prevalence among the total isolates was 18.5 % (63/340) and was higher among inpatient isolates (23.0 %) than outpatient isolates (11.8 %, P<0.001), and higher among isolates from patients aged ≥65 years than from patients aged 18–50 years and 51–64 years (25.4 vs 3.4 and 4.0 %, respectively, P<0.001). Of the 63 ST131 isolates, 43 (68.3 %) isolates belonged to the H30 subclone, whereas the remaining isolates belonged to H41 (n = 17), H54 (n = 2) and H22 (n = 1). All H30 isolates were ciprofloxacin-resistant, of which 18.6 % (8/43) belonged to the H30-Rx subclone. Twenty-six (41.3 %) ST131 isolates were ESBL-producers, of which 19 had bla CTX-M-14 (12 non-H30-Rx, two H30-Rx and five H41), six had bla CTX-M-15 (five non-H30-Rx and one H30-Rx) and one was bla CTX-M-negative (H30). In conclusion, ST131 accounts for a large share of the antimicrobial-resistant E. coli isolates from geriatric patients. Unlike previous reports, ESBL-producing ST131 strains mainly belonged to non-H30-Rx rather than the H30-Rx subclone, with bla CTX-M-14 as the dominant enzyme type.postprin