Identification of AbaR4 Acinetobacter baumannii resistance island in clinical isolates of blaOXA-23-positive Proteus mirabilis.

OBJECTIVES: bla OXA-23 is a class D carbapenemase-encoding gene typical of the Acinetobacter genus. However, its occurrence in the Enterobacteriaceae is uncommon. Here we provide the genome characterization of blaOXA-23-positive Proteus mirabilis. METHODS: In Singapore, a national surveillance of carbapenem non-susceptible clinical Enterobacteriaceae has enabled the collection of OXA-23 bearing isolates. Three clinical P. mirabilis were whole-genome sequenced using Oxford Nanopore MinION and Illumina platforms. The sequence accuracy of MinION long-read contigs was enhanced by polishing with Illumina-derived short-read data. RESULTS: In two P. mirabilis genomes, blaOXA-23 was detected as two copies, present on the chromosome and on a 60018 bp plasmid. blaOXA-23 was associated with the classic Acinetobacter composite transposon Tn2006, bounded by two copies of ISAba1 bracketing the carbapenemase gene. The Tn2006 itself was embedded within an Acinetobacter baumannii AbaR4 resistance island. In the chromosome, the AbaR4 was found integrated into the comM gene, which is also the preferred 'hotspot' in A. baumannii. In the plasmid, AbaR4 integrated into a putative colicin gene. CONCLUSIONS: Our description of an A. baumannii AbaR4 encoding blaOXA-23 in P. mirabilis is to our knowledge the first description of an Acinetobacter resistance island in Proteus and suggests that P. mirabilis may be a reservoir for this class D carbapenemase gene.

Challenge of drug resistance in Pseudomonas aeruginosa: clonal spread of NDM-1-positive ST-308 within a tertiary hospital.

OBJECTIVES: MDR Pseudomonas aeruginosa is a serious global threat to healthcare institutions. The mechanism by which drug resistance can be acquired is variable, but acquired carbapenemase production has been reported in P. aeruginosa. An investigation was performed to determine the rate and genomic epidemiology of New Delhi MBL (NDM) in ß-lactam-non-susceptible isolates. METHODS: P. aeruginosa isolates from a tertiary hospital in Singapore between January 2015 and February 2018 were investigated for the presence of NDM genes. RESULTS: Out of 298 pan-ß-lactam-non-susceptible isolates, 31 were found to be NDM positive (10.4%). WGS demonstrated that all 31 NDM-positive isolates were clonal, belonging to ST-308. blaNDM was chromosomally inserted within an integrative and conjugative element (ICE), ICETn43716385. The NDM-P. aeruginosa isolates possessed an extensive repertoire of both cell-associated [flagella, pili, alginate/biofilm, LPS, type III secretion system (T3SS) and type VI secretion system (T6SS)] and secreted virulence factors. Antibiograms revealed higher rates of drug resistance in NDM-positive isolates compared with their non-NDM counterparts. The NDM isolates remained 100% susceptible only to colistin. CONCLUSIONS: The combination of chromosomal mutations, acquired resistance genes and virulence factors likely facilitated the persistent and ongoing spread of the ST-308 clade of P. aeruginosa within the hospital. Our study illustrates the particular threat of NDM-positive P. aeruginosa in a tertiary hospital setting in the era of antimicrobial resistance.

Klebsiella pneumoniae and Klebsiella quasipneumoniae define the population structure of blaKPC-2Klebsiella: a 5 year retrospective genomic study in Singapore.

OBJECTIVES: To describe the population structure, molecular epidemiology and genetic context of blaKPC-2-bearing Klebsiella pneumoniae. METHODS: Isolates (n = 157) were retrospective, phenotypically carbapenem-resistant blaKPC-positive K. pneumoniae, collected from public hospitals. WGS was performed on the Illumina platform. Phylogenomic analysis, screening of resistance and virulence genes, and comparison of the genetic environment of blaKPC were carried out. RESULTS: Based on core-tree phylogeny, 67.5% of the isolates were K. pneumoniae and the remainder comprised Klebsiella quasipneumoniae. No Klebsiella variicola strains were observed. Only a single K. pneumoniae carbapenemase (KPC) variant type, blaKPC-2, was seen. MLSTs were diverse and did not comprise the 'traditional' KPC clonal group (CG) 258. blaKPC-2 was associated with a non-Tn4401 element (NTE) in >99% of genomes. Screening for four key virulence loci: yersiniabactin (ybt), aerobactin (iuc), salmochelin (iro) and colibactin (clb) as well as ICEKp (virulence-associated integrative conjugative element of K. pneumoniae), revealed the lack of virulence factors and ICEKp within K. quasipneumoniae. Amongst the K. pneumoniae, there were 32 ybt+ isolates (32/106, 30.2%) and, of these, 8 isolates were also clb+ (7.5%). K. pneumoniae serotypes K1 and K2, the majority of capsular serotype seen in patients with invasive liver abscess syndrome, were detected at 4.5% (7/157). CONCLUSIONS: Results suggest that dissemination of blaKPC-2 is driven by NTEKPC in non-ST258 isolates. The detection of blaKPC-2K. pneumoniae serotypes K1/K2 carrying virulence factors, albeit in low numbers, reflects the worrisome convergence of carbapenem resistance and hypervirulence in K. pneumoniae.

Pre-operative intravenous steroid improves pain and joint mobility after total knee arthroplasty in Chinese population: a double-blind randomized controlled trial.

INTRODUCTION: This study aims to investigate the effect of pre-operative intravenous methylprednisolone on post-operative pain control and joint mobility in Chinese patients undergoing single primary total knee arthroplasty. METHODS: This is a prospective, randomized, double-blinded, placebo-controlled single-centre trial. Sixty subjects were randomized into intervention and control group. The peri-operative anaesthetic and analgesic regimes were standardized. The intervention group received 125 mg methylprednisolone intravenously on the induction of anaesthesia. Subjects were assessed at 24, 30 and 48 h after surgery and upon discharge for pain scores and range of movement from the operated knee. Change in C-reactive protein level was calculated. Patient's satisfaction was recorded. Adverse reactions were documented. Subjects were followed up at 6 weeks, 4 months and 1 year. RESULTS: Rest pain and pain on movement were significantly reduced in the methylprednisolone group at 24 and 30 h after surgery (ANOVA p = 0.030, p = 0.003, p = 0.032, p = 0.010). The methylprednisolone group demonstrated a greater range of movement from the operated knee up to 30 h after surgery (ANOVA p = 0.031). Post-operative C-reactive protein level was significantly less in the methylprednisolone group (p < 0.001). Methylprednisolone group had a higher patient's satisfaction than the control group (p < 0.01). No adverse effects were noted at the 1-year follow-up. CONCLUSION: Pre-operative intravenous methylprednisolone improves post-operative pain and joint mobility after total knee arthroplasty up to 30 h after operation. It results in a higher patients' satisfaction. It can act as an effective adjunct in the multimodal analgesic regime. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT03082092.

Manipulating turn residues on de novo designed ß-hairpin peptides for selectivity against drug-resistant bacteria.

Synthetic ß-hairpin antimicrobial peptides (AMPs) offer a useful source for the development of novel antimicrobial agents. ß-hairpin peptides generally consist of two side strands bridged by a reverse turn. In literature, most studies focused on the modifications of the side strands to manipulate the stability and activity of ß-hairpin peptides, and much less is known about the impact of the turn region. By designing a series of de novo ß-hairpin peptides with identical side strands but varied turns, we demonstrated that mutations of only 2 to 4 amino acids at the turn region could impart a wide range of antimicrobial profiles among synthetic ß-hairpin AMPs. BTT2-4 and BTT6 displayed selective potency against Gram-negative bacteria, with minimum inhibitory concentrations (MICs) of 4-8 µM. In contrast, BTT1 exhibited broad-spectrum activity, with MICs of 4-8 µM against both Gram-positive and Gram-negative strains. Additionally, BTT1 was potent against methicillin-resistant Staphylococcus aureus (MRSA) and colistin-resistant Enterobacterales. The antimicrobial potency of BTT1 persisted after 14 days of serial passage. Mechanistic studies revealed that interactions between lipopolysaccharide (LPS) and the peptides were critical to their membranolytic activity against the bacterial inner membrane. Aside from folding stability, we observed that a degree of conformational flexibility was required for disruptive membrane interactions. STATEMENT OF SIGNIFICANCE: By examining the significance of the turn region of ß-hairpin peptides, we present valuable knowledge to the design toolkit of novel antimicrobial peptides as alternative therapeutics to overcome antibiotic resistance. Our de novo designed synthetic peptides displayed selective activity against Gram-negative bacteria and potent activity against clinically relevant antibiotic-resistant strains (e.g. colistin-resistant Enterobacterales and methicillin-resistant Staphylococcus aureus). The bactericidal activity of our peptides was shown to be robust in the presence of proteolytic trypsin and saline, conditions that could suppress peptide activity. Our peptides were also determined to be non-cytotoxic against a human cell line.

Prevalence of Flexor Carpi Radialis Brevis in Chinese Patients with Volar Wrist Plating Performed for Distal Radius Fracture.

Background: Volar locking plates were increasing popular as treatment of distal radius fractures. Various distal forearm anatomical variants were encountered during surgery. Flexor carpi radialis brevis (FCRB) was one of the most common and relevant anatomical variants because of its close proximity to fracture site. Methods: This is a retrospective single-centre study. In a 3.5-year period from March 2015 to August 2018, 133 patients who suffered from distal radius fracture requiring volar wrist plating were identified. Operation records and clinical photos were reviewed. All patients were followed up for at least 1 year. Any complications were recorded. Results: 9 patients with FCRB variant were identified. The prevalence was 6.8%. Hypoplastic pronator quadratus were found in 5 cases out of the 9 cases. None of these cases had any neurovascular injuries. No complications were noted during follow-up at 1 year. Conclusions: In Chinese population with volar locking plate done for distal radius fracture, the prevalence of flexor carpi radialis brevis was 6.8%. Surgeons should be aware of the possibility of FCRB variant.

The diagnostic and management challenge for concomitant fragility fractures of pelvis and hip - a Case series with literature review.

BACKGROUND: Fragility fractures of hip and pelvis in the elderly population are common. They do co-exist but are frequently missed and undertreated. METHODS AND RESULTS: 3 cases of concomitant fragility fractures of hip and pelvis were identified. Hip fractures were treated with cemented hemiarthroplasty or cephalomedullary nail fixation, while pelvic fractures were treated with percutaneous screw fixation in same general anesthesia session. Anti-osteoporotic treatments were offered. Subjects were followed up for 1 year. CONCLUSION: Surgical treatment of fragility hip and pelvic fractures improves fracture stability, achieves better pain relief and allows earlier mobilization. Anti-osteoporotic treatment is essential as secondary prevention in fragility fractures.

Tedizolid Activity Against Clinical Mycobacterium abscessus Complex Isolates-An in vitro Characterization Study.

Mycobacterium abscessus complex consist of three rapidly growing subspecies: M. abscessus, M. massiliense, and M. bolletii. They are clinically important human pathogens responsible for opportunistic pulmonary and skin and soft tissue infections. Treatment of M. abscessus infections is difficult due to in vitro resistance to most antimicrobial agents. Tedizolid (TZD) is a next-generation oxazolidinone antimicrobial with a wide spectrum of activity even against multidrug resistant Gram-positive bacteria. In this study, the in vitro activity of TZD against the M. abscessus complex (n = 130) was investigated. Susceptibility testing by broth microdilution showed lower TZD minimum inhibitory concentrations (MICs) when compared to linezolid. The MIC50 and MIC90 was 1 mg/L and 4 mg/L, respectively across all M. abscessus complex members, reflecting no difference in subspecies response to TZD. Pre-exposure of M. abscessus complex to subinhibitory concentrations of TZD did not trigger any inducible drug resistance. Single-drug time kill assays and bactericidal activity assays demonstrated bacteriostatic activity of TZD in all three M. abscessus subspecies, even at high drug concentrations of 4 to 8x MIC. Combination testing of TZD with clarithromycin, doxycycline and amikacin using the checkerboard approach showed no antagonistic interactions. TZD may be an effective therapeutic antimicrobial agent for the treatment of M. abscessus infections.

Age and etiology of childhood epidermolysis bullosa mortality.

Epidermolysis bullosa (EB) is a heterogeneous group of congenital blistering diseases that are usually present in the neonatal period. They are characterized by blister formation in response to rubbing or frictional trauma. EB is classified into three major categories, each with many subtypes based on the precise location at which separation or blistering occurs, namely epidermolysis bullosa simplex (EBS), junctional epidermolysis bullosa (JEB), and dystrophic epidermolysis bullosa (DEB). We describe the causes and ages of death of three cases of EB in Hong Kong. A 24-year-old male with EBD diagnosed in the neonatal period lived a withdrawn life after completing secondary school and died of metastaic squamous cell carcinoma. Two neonates of consanguineous Pakistani parents, one with JEB and the other with EB-Pyloric Atresia variant, died of sepsis in infancy. We performed an extensive literature review of the causes and ages of death of these diseases. EB is a heterogeneous inherited blistering skin disease associated with significant morbidity and mortality. EBS is occasionally associated with death at early ages with sepsis. Patients with JEB usually died of sepsis at young age. DEB patients often survive to adulthood and die of cardiopulmonary and renal complications. Squamous cell carcinoma and metastases are unique in DEB.

Septicemia in a Neonate following Therapeutic Hypothermia: The Literature Review of Evidence.

We report a term neonate with hypoxic ischemic encephalopathy who underwent a 72-hour therapeutic hypothermia. He developed unstable body temperature associated with coagulase negative staphylococcus septicemia 2 weeks later which was promptly treated with intravenous antibiotics and made a good recovery. PubMed (a service of the U.S. National Library of Medicine) was searched for the terms "therapeutic hypothermia" and "septicemia," with limits activated (humans, English, age 0-18 years). There were only 6 randomized controlled trials, 1 non-randomized controlled trial, 1 retrospective cohort, and 1 case-control trial, which showed no definite evidence of increased risk of septicemia or neutrophil dysfunction in infants following hypothermia therapy.