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    The Characterisation of Carbapenem-Resistant Acinetobacter baumannii and Klebsiella pneumoniae in a Teaching Hospital in Malaysia.
    (MDPI (Basel, Switzerland), 2024-11-20) Lau MY; Ponnampalavanar S; Chong CW; Dwiyanto J; Lee YQ; Woon JJ; Kong ZX; Jasni AS; Lee MCC; Obaidellah UH; Teh CSJ; Christodoulides M
    Background/Objectives: The emergence and dissemination of carbapenem-resistant organisms, particularly Acinetobacter baumannii and Klebsiella pneumoniae, pose a significant threat to healthcare systems worldwide. This retrospective study aims to characterise carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Klebsiella pneumoniae (CRKP) strains in a teaching hospital and to determine the risk factors associated with patients' in-hospital mortality. Methods: A total of 90 CRAB and 63 CRKP were included in this study. Carbapenemase genes and MLST types of CRAB and CRKP were determined using specific primers. Risk factors associated with in-hospital mortality were analysed with collected data. Results: All the CRAB strains consisted of OXA carbapenemase genes, with 98% of the strains co-harbouring blaOXA-23-like and blaOXA-51-like carbapenemase genes. Conversely, blaNDM is the predominant carbapenemase gene in CRKP, followed by blaOXA-48-like carbapenemase genes. ST2 and ST20 are the dominant MLST types in CRAB and CRKP, respectively. In CRAB, multivariate analysis identified age, ethnicity, the presence of a mechanical ventilator, and patients who experienced previous exposure to clindamycin in the last 90 days as associated with an increased risk of in-hospital mortality. In contrast, older age, male, ICU admission, and the presence of an indwelling urinary catheter were significantly associated with an increased risk of mortality for patients with CRKP. Conclusions: Both CRAB and CRKP lead to high rates of mortality. The MLST profile showed that the genomic patterns of CRKP were highly diverse, whereas CRAB strains had low genetic diversity. To tackle these challenging pathogens, robust surveillance and an in-depth understanding of molecular epidemiology and genomics studies are needed to tailor infection control strategies and individualise treatment approaches.
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    Clinical parameters of hypervirulent Klebsiella pneumoniae disease and ivermectin treatment in New Zealand sea lion (Phocarctos hookeri) pups
    (PLOS, 2022-03-03) Michael SA; Hayman DTS; Gray R; Roe WD; Raverty S
    Hypervirulent Klebsiella pneumoniae infection causes significant mortality of endangered New Zealand sea lion pups at Enderby Island, Auckland Islands. Gross necropsy and histopathology findings are well reported, but little is known about the clinical course of disease in affected pups. To determine factors feasible as clinical screening tools for hypervirulent K. pneumoniae in live pups, 150 pups over two field seasons (2016-18) were recruited shortly after birth for a prospective cohort study. A randomised controlled clinical treatment trial with the anthelmintic ivermectin was conducted concurrently and risk factor data and biological samples were collected approximately fortnightly. Treatment with ivermectin has been demonstrated to reduce the risk of hypervirulent K. pneumoniae mortality in pups, so effects on clinical parameters between the treated and control cohorts were also investigated. A broader sample of pups were monitored for clinical signs to investigate the course of disease in affected pups. Clinical signs, haematology and oral and rectal swabs to detect gastrointestinal carriage of hypervirulent K. pneumoniae were not useful for detection of disease prior to death. Of those pups that died due to hypervirulent K. pneumoniae, only 26.1% (18/69) had any clinical signs prior, likely a reflection of the peracute course of disease. On comparison of haematological parameters between ivermectin-treated and control pups, significantly lower total plasma protein and higher eosinophil counts were seen in control versus treated pups, however standard length as a surrogate for age was a more important influence on parameters overall than ivermectin treatment. This study also highlighted a cohort of pups with severe clinical signs suggestive of hypervirulent K. pneumoniae infection were lost to follow up at the end of the monitored season, which could be contributing to cryptic juvenile mortality.
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    Risk Factors for New Zealand Sea Lion (Phocarctos hookeri) Pup Mortality: Ivermectin Improves Survival for Conservation Management
    (Frontiers Media S.A., 2021-07-09) Michael SA; Hayman DTS; Gray R; Roe WD; Davis RW
    Septicaemia due to hypervirulent (HV) Klebsiella pneumoniae is the leading cause of neonatal pup mortality in endangered New Zealand sea lions (Phocarctos hookeri) at Enderby Island, in the New Zealand sub-Antarctic. Accounting for approximately 60% of annual pup mortality at this site following an epizootic event in 2001–02, HV K. pneumoniae is also emerging worldwide as a significant community-acquired human pathogen. To facilitate efficient direct mitigation to reduce pup mortality, a case-control study and prospective cohort study were conducted to identify risk factors amenable to active management. Additionally, to investigate impacts of hookworm (Uncinaria spp.), a nested treatment trial with the anthelmintic ivermectin was undertaken concurrently. During two austral summer field seasons (2016–2018), 698 pups were captured for treatment trial recruitment and the collection of morphometric measurements, biological samples and risk factor data. Gastrointestinal carriage of the virulent phenotype of K. pneumoniae was a consistent risk factor, while ivermectin treatment and higher body condition index consistently reduced risk of HV K. pneumoniae mortality. Significantly fewer ivermectin-treated pups were found dead (24.1% control, 11.1% treatment), with a trend towards a higher proportion of HV K. pneumoniae deaths amongst the control group. This study provides evidence to support ivermectin treatment as a pup mortality mitigation strategy in New Zealand sea lions at Enderby Island. If applied to larger colonies where HV K. pneumoniae and hookworm impact pup survival, this intervention could have population-scale benefits for this endangered species. Further work is required to understand how ivermectin prevents HV K. pneumoniae septicaemia, but removal of hookworms before intestinal mucosal damage occurs could limit systemic spread of virulent bacteria from the gastrointestinal tract.
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    Klebsiella pneumoniae in New Zealand sea lions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2018) Pinpimai, Komkiew
    Klebsiella pneumoniae has been circulating in New Zealand sea lions since the outbreaks during the breeding seasons of 2001/02 and 2002/03 in Sandy Bay, on Enderby Island, Auckland Islands. A large number of pups have since died from K. pneumoniae every year during the breeding season. In order to prevent and control this infection, baseline data including bacterial phenotype and genotype, geographic distribution of the pathogen, and the immune response to the pathogen, have to be established. In this study, hypervirulent (HV) K. pneumoniae was isolated from different sources including New Zealand sea lion (NZSL) pups from different breeding sites, and characterised using a combination of biochemical, phenotypic tests, serological analysis and genotyping via whole genome sequencing. Isolates from pups, substrate samples from different breeding sites, a NZSL adult and birds, all had a close genetic relationship. The isolates have the same basic characteristics including a hypermucoviscous phenotype, serotype 2, and sequence type 86. This suggested clonality of this pathogen. The geographic distribution of the pathogen was found to be Enderby Island, Dundas Island, Campbell Island, and the Otago Peninsula (New Zealand mainland). The isolates analysed were all susceptible to commonly used antibiotics, with the exception of ampicillin. The HV isolates from pups were able to utilise a wide panel of carbon and nitrogen sources and had activity in a wide range of pH from 4.5 to 10, supporting the ability of this pathogen to survive in diverse environments. The findings in this thesis also suggest that the environment can be a reservoir for a short time period. For the long term, between breeding seasons, New Zealand sea lion adults and birds that live around the breeding site are potential reservoirs. The HV isolates from pups were resistant to some innate immune responses, including serum killing ability, oxidative killing ability and phagocytosis by neutrophils and monocytes. Overall, this study provided phenotypic and genotypic information on K. pneumoniae isolated from NZSL pups, as well as some information about innate immune responses to this pathogen, which can aid in the prevention and control of this infection.
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    Causes of mortality and characterisation of Mycobacteriosis in adult New Zealand sea lions (Phocarctos Hookeri) at Enderby Island : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science in Wildlife Health at Massey University, Manawatū, Palmerston North, New Zealand
    (Massey University, 2017) Lenting, Baukje Mirjam
    The New Zealand sea lion (Phocarctos hookeri) is classified as endangered and “Nationally Critical” due to a declining population and restricted population range. There have been recent bacterial epizootic events at the breeding colonies of this species, however the role of disease in the population decline is not known. As part of the investigation into the population decline, the species management plan recommends investigation of disease agents affecting this species, their epidemiology and their long-term effects on population dynamics. Since the 1998/1999 breeding season, post mortem examinations have been performed on deceased New Zealand sea lions at the Enderby Island breeding colonies during each breeding season, including the collection of samples for histology and bacteriology. This study describes the causes of mortality in New Zealand sea lions one year of age and older at Enderby Island between the 1998/99 to 2010/11 breeding seasons inclusive, using the archived post mortem reports, histology samples and bacteriology samples. Conspecific trauma was found to be a significant cause of mortality (34.3%), as were various infectious causes (35.7%). The organism Klebsiella pneumoniae was isolated from non-pup New Zealand sea lions both from individuals that died from other causes and individuals that showed apparent morbidity as a result of this bacteria. These findings suggest that older animals may be reservoirs of infection for K. pneumoniae, which causes significant mortality in neonatal New Zealand sea lions. Another important infectious agent that was described in non-pup New Zealand sea lions was Mycobacterium pinnipedii, which caused both subclinical and clinical disease. Mycobacteriosis of the lymph nodes, lungs, pleura, liver, peritoneum and reproductive tract was described in this study. Strain determination of the M. pinnipedii isolates grown show only minor strain variation among isolates, which may reflect the isolated geographic distribution of these animals. There was no apparent association between the individual strains of M. pinnipedii and their pathogenicity as indicated by the pathology present in infected animals.
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    A study of brain injury in New Zealand sea lion pups : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand
    (Massey University, 2011) Roe, Wendi Dianne
    The New Zealand sea lion (Phocarctos hookeri) is a threatened species endemic to New Zealand. The majority of breeding in this species occurs on the Auckland Islands in the sub-Antarctic, and recent population estimates indicate that pup production is declining. Trauma is a significant cause of mortality in New Zealand sea lion pups, and much of this is believed to be caused by adult and subadult males, that bite, crush, shake and throw young pups. In this thesis, a number of techniques are used to determine the role played by traumatic brain injury in the mortality of NZ sea lion pups. The findings of gross necropsy examinations show that pups have numerous lesions indicative of traumatic brain injury, including skull fractures and subdural haemorrhages, and that pups die due to crushing and impact injuries. Although some pups have gross lesions considered in human paediatric medicine to be indicative of shaking injury, detailed histological and microbiological studies of sea lion pups show that most of these are associated with meningitis due to Klebsiella pneumoniae. This bacterium is a common cause of pup mortality. Immunohistochemical techniques are used to demonstrate that axonal injury is common in sea lion pups, but show that shaking is not a common mechanism of this pathological process. Instead, most axonal injury is found to be due to hypoxia-ischaemia, and evidence that raised intracranial pressure has occurred is comparatively common in dead pups. The combined findings of histological and immunohistochemical studies suggest that lesions such as optic sheath haemorrhage, intracranial subdural haemorrhage, spinal sub-meningeal haemorrhage, and optic nerve axonal injury could be caused by pertubations to vascular, intra-ocular, intracranial and subarachnoid pressure rather than being a direct result of trauma as is proposed in shaken baby syndrome.
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    Causes of neonatal mortality in the New Zealand sea lion (Phocarctos Hookeri) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Pathology at Massey University, Palmerston North, New Zealand
    (Massey University, 2006) Castinel, Aurelie
    As part of a health survey of New Zealand sea lions (Phocarctos hookeri) on Enderby Island, Auckland Islands (50°30’S, 166°17’E), neonatal mortality was continuously monitored at the Sandy Bay Beach rookery, from 1998/1999 to 2004/2005. The primary causes of death were categorised as trauma (35%), bacterial (24%) and hookworm (13%) infections, starvation (13%) and stillbirth (4%). During the 2001/2002 and 2002/2003 breeding seasons, bacterial epidemics caused by Klebsiella pneumoniae increased mortality by three times the mean in non-epidemic years. Uncinaria spp. from New Zealand sea lion (NZSL) pups was described for the first time using morphometric criteria. It differed from the two species already described in pinnipeds, Uncinaria lucasi and Uncinaria hamiltoni, suggesting the existence of a different morphotype in NZSLs. A study on the epidemiology of hookworm infection showed that all pups up to at least three months of age harboured adult hookworms in their intestines and transmammary transmission was identified as the route of infection of NZSL pups. Uncinariosis as a primary cause of mortality was generally associated with anaemia, haemorrhagic enteritis and frank blood in the lumen. The relationship between hookworm burden and clinical disease could not be clearly established. The 2001/2002 and 2002/2003 bacterial epidemics at Sandy Bay Beach rookery were caused by a clonal strain of Klebsiella pneumoniae as verified by pulse-field gel electrophoresis and antimicrobial testing. Suppurative arthritis was the most common post-mortem diagnosis during the two epidemic seasons. Internal lesions were consistent with septicaemia, which explained the wide range of organs from which the pathogen was grown in pure culture. A serological test investigating the exposure of NZSLs to Klebsiella spp. showed that the large majority of pups up to two months of age did not have any anti-Klebsiella antibodies, even after the epidemics, but that almost all the adults were seropositive. In addition, passive immunoglobulin (Ig) transfer from lactating females to neonates was examined by measuring IgG levels in pups and was very low compared to terrestrial mammals although similar to other pinniped neonates.