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Bain W, Ahn B, Peñaloza HF, McElheny CL, Tolman N, van der Geest R, Gonzalez-Ferrer S, Chen N, An X, Hosuru R, Tabary M, Papke E, Kohli N, Farooq N, Bachman W, Olonisakin TF, Xiong Z, Griffith MP, Sullivan M, Franks J, Mustapha MM, Iovleva A, Suber T, Shanks RQ, Ferreira VP, Stolz DB, Van Tyne D, Doi Y, Lee JS. In Vivo Evolution of a Klebsiella pneumoniae Capsule Defect With wcaJ Mutation Promotes Complement-Mediated Opsonophagocytosis During Recurrent Infection. J Infect Dis 2024; 230:209-220. [PMID: 39052750 PMCID: PMC11272070 DOI: 10.1093/infdis/jiae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/17/2023] [Accepted: 01/03/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Klebsiella pneumoniae carbapenemase-producing K pneumoniae (KPC-Kp) bloodstream infections are associated with high mortality. We studied clinical bloodstream KPC-Kp isolates to investigate mechanisms of resistance to complement, a key host defense against bloodstream infection. METHODS We tested growth of KPC-Kp isolates in human serum. In serial isolates from a single patient, we performed whole genome sequencing and tested for complement resistance and binding by mixing study, direct enzyme-linked immunosorbent assay, flow cytometry, and electron microscopy. We utilized an isogenic deletion mutant in phagocytosis assays and an acute lung infection model. RESULTS We found serum resistance in 16 of 59 (27%) KPC-Kp clinical bloodstream isolates. In 5 genetically related bloodstream isolates from a single patient, we noted a loss-of-function mutation in the capsule biosynthesis gene, wcaJ. Disruption of wcaJ was associated with decreased polysaccharide capsule, resistance to complement-mediated killing, and surprisingly, increased binding of complement proteins. Furthermore, an isogenic wcaJ deletion mutant exhibited increased opsonophagocytosis in vitro and impaired in vivo control in the lung after airspace macrophage depletion in mice. CONCLUSIONS Loss of function in wcaJ led to increased complement resistance, complement binding, and opsonophagocytosis, which may promote KPC-Kp persistence by enabling coexistence of increased bloodstream fitness and reduced tissue virulence.
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Affiliation(s)
- William Bain
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
- Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania
| | - Brian Ahn
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus School of Medicine, Denver
| | - Hernán F Peñaloza
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | | | - Nathanial Tolman
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Rick van der Geest
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Shekina Gonzalez-Ferrer
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Nathalie Chen
- Division of Infectious Diseases, Department of Medicine
| | - Xiaojing An
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Ria Hosuru
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Mohammadreza Tabary
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Erin Papke
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Naina Kohli
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | | | | | - Tolani F Olonisakin
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Zeyu Xiong
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | | | - Mara Sullivan
- Center for Biologic Imaging, Department of Cell Biology
| | | | | | - Alina Iovleva
- Division of Infectious Diseases, Department of Medicine
| | - Tomeka Suber
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
| | - Robert Q Shanks
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Ohio
| | - Donna B Stolz
- Center for Biologic Imaging, Department of Cell Biology
| | | | - Yohei Doi
- Division of Infectious Diseases, Department of Medicine
| | - Janet S Lee
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh
- Division of Pulmonary and Critical Care Medicine, Washington University in St Louis, Missouri
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2
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Heinz E, Pearse O, Zuza A, Bilima S, Msefula C, Musicha P, Siyabu P, Tewesa E, Graf FE, Lester R, Lissauer S, Cornick J, Lewis JM, Kawaza K, Thomson NR, Feasey NA. Longitudinal analysis within one hospital in sub-Saharan Africa over 20 years reveals repeated replacements of dominant clones of Klebsiella pneumoniae and stresses the importance to include temporal patterns for vaccine design considerations. Genome Med 2024; 16:67. [PMID: 38711148 PMCID: PMC11073982 DOI: 10.1186/s13073-024-01342-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 04/30/2024] [Indexed: 05/08/2024] Open
Abstract
BACKGROUND Infections caused by multidrug-resistant gram-negative bacteria present a severe threat to global public health. The WHO defines drug-resistant Klebsiella pneumoniae as a priority pathogen for which alternative treatments are needed given the limited treatment options and the rapid acquisition of novel resistance mechanisms by this species. Longitudinal descriptions of genomic epidemiology of Klebsiella pneumoniae can inform management strategies but data from sub-Saharan Africa are lacking. METHODS We present a longitudinal analysis of all invasive K. pneumoniae isolates from a single hospital in Blantyre, Malawi, southern Africa, from 1998 to 2020, combining clinical data with genome sequence analysis of the isolates. RESULTS We show that after a dramatic increase in the number of infections from 2016 K. pneumoniae becomes hyperendemic, driven by an increase in neonatal infections. Genomic data show repeated waves of clonal expansion of different, often ward-restricted, lineages, suggestive of hospital-associated transmission. We describe temporal trends in resistance and surface antigens, of relevance for vaccine development. CONCLUSIONS Our data highlight a clear need for new interventions to prevent rather than treat K. pneumoniae infections in our setting. Whilst one option may be a vaccine, the majority of cases could be avoided by an increased focus on and investment in infection prevention and control measures, which would reduce all healthcare-associated infections and not just one.
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Affiliation(s)
- Eva Heinz
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK.
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK.
| | - Oliver Pearse
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Allan Zuza
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Sithembile Bilima
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Patrick Musicha
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Edith Tewesa
- Queen Elizabeth Central Hospital, Blantyre, Malawi
| | - Fabrice E Graf
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK
| | - Rebecca Lester
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Division of Infection & Immunity, University College London, London, UK
| | - Samantha Lissauer
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Jennifer Cornick
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Joseph M Lewis
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Kondwani Kawaza
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Nicholas R Thomson
- Parasites and Microbes Program, Wellcome Sanger Institute, Hinxton, UK
- London School of Hygiene and Tropical Medicine, London, UK
| | - Nicholas A Feasey
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke PlaceLiverpool, L3 5QA, UK.
- Malawi Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi.
- School of Medicine, St Andrews University, St Andrews, UK.
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3
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Shen Z, Qin J, Xiang G, Chen T, Nurxat N, Gao Q, Wang C, Zhang H, Liu Y, Li M. Outer membrane vesicles mediating horizontal transfer of the epidemic blaOXA-232 carbapenemase gene among Enterobacterales. Emerg Microbes Infect 2023; 13:2290840. [PMID: 38044873 PMCID: PMC10810626 DOI: 10.1080/22221751.2023.2290840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
OXA-232 is one of the most common OXA-48-like carbapenemase derivatives and is widely disseminated in nosocomial settings across countries. The blaOXA-232 gene is located on a 6-kb non-conjugative ColKP3-type plasmid, while the dissemination of blaOXA-232 into different Enterobacterales species and the polyclonal dissemination of OXA-232-producing K. pneumoniae revealed the horizontal transfer of blaOXA-232. However, it's still unclear how this non-conjugative ColKP3 plasmid could facilitate the mobilization of blaOXA-232. Here, we observed the in vivo intraspecies transfer of blaOXA-232 during a nosocomial outbreak of OXA-232-producing K. pneumoniae. We demonstrated the presence of ColKP3 OXA-232 plasmid in the outer membrane vesicles (OMVs) derived from clinical isolates, and OMVs could facilitate the horizontal transfer of blaOXA-232 among Enterobacterales. In contrast, for the most prevalent carbapenemase genes, including blaKPC-2 and blaNDM-1, though the presence of carbapenemase genes and plasmid backbones in the vesicular lumen was observed, OMVs couldn't promote effective transformation, probably due to the low copy number of plasmids in clinical isolates and the low number of plasmids loaded into vesicles. Conjugation assay revealed that the epidemic IncX3 NDM-1 and IncFII(pHN7A8)/IncR KPC-2 plasmids were conjugative and could be horizontally transferred via independent conjugation or with the help of a co-existent conjugative plasmid. For the large-size and low-copy number conjugative plasmids carrying carbapenemase genes, OMVs-mediated gene exchange may only serve as an alternative pathway for horizontal transfer. In conclusion, diverse mobilization strategies were employed by plasmids harboring carbapenemase genes, and plasmids display a proper choice of mobility pathway due to their individual properties.
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Affiliation(s)
- Zhen Shen
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Juanxiu Qin
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Guoxiu Xiang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Tianchi Chen
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Nadira Nurxat
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Qianqian Gao
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Chen Wang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Haomin Zhang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Yao Liu
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, US National Institutes of Health, Bethesda, MD, USA
| | - Min Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
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Huang JM, Sung KC, Lin WC, Lai HY, Wang YJ. Enhancement of capsular hypermucoviscosity in Klebsiella pneumoniae by Acanthamoeba. PLoS Negl Trop Dis 2023; 17:e0011541. [PMID: 37566587 PMCID: PMC10495012 DOI: 10.1371/journal.pntd.0011541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 09/11/2023] [Accepted: 07/18/2023] [Indexed: 08/13/2023] Open
Abstract
BACKGROUND Acanthamoeba and Klebsiella pneumoniae are both environmental commensals. Recently, clinical harm caused by hypermucoviscous K. pneumoniae has been observed. However, the interaction between these microbes and the origin of hypermucoviscous K. pneumoniae have not been reported. METHODOLOGY/PRINCIPAL FINDINGS Here, we report that the bacterial capsule is enlarged when co-cultured with Acanthamoeba using India ink staining, and this effect depends on the number of parasites present. This interaction results in an enhancement of capsular polysaccharide production in the subsequent generations of K. pneumoniae, even without co-culturing with Acanthamoeba. The hypermucoviscosity of the capsule was examined using the sedimentation assay and string test. We also screened other K. pneumoniae serotypes, including K1, K2, K5, and K20, for interaction with Acanthamoeba using India ink staining, and found the same interaction effect. CONCLUSIONS/SIGNIFICANCE These findings suggest that the interaction between Acanthamoeba and K. pneumoniae could lead to harmful consequences in public health and nosocomial disease control, particularly hypermucoviscous K. pneumoniae infections.
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Affiliation(s)
- Jian-Ming Huang
- School of Medicine, National Tsing Hua University, Hsinchu, Taiwan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Ko-Chiang Sung
- Department of Clinical Laboratory, Chest Hospital, Ministry of Health and Welfare, Tainan, Taiwan
| | - Wei-Chen Lin
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Parasitology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Hong-Yue Lai
- Department of Pharmacology, School of Medicine, China Medical University, Taichung, Taiwan
| | - Yu-Jen Wang
- Department of Parasitology, School of Medicine, China Medical University, Taichung, Taiwan
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5
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Hallal Ferreira Raro O, Nordmann P, Dominguez Pino M, Findlay J, Poirel L. Emergence of Carbapenemase-Producing Hypervirulent Klebsiella pneumoniae in Switzerland. Antimicrob Agents Chemother 2023; 67:e0142422. [PMID: 36853006 PMCID: PMC10019205 DOI: 10.1128/aac.01424-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/19/2023] [Indexed: 03/01/2023] Open
Abstract
Increasing occurrence of multidrug-resistant (MDR) and hypervirulent (hv) Klebsiella pneumoniae (MDR-hvKp) convergent clones is being observed. Those strains have the potential of causing difficult-to-treat infections in healthy adults with an increased capacity for mortality. It is therefore crucial to track their dissemination to prevent their further spread. The aim of our study was to investigate the occurrence of carbapenemase-producing hvKp isolates in Switzerland and to determine their genetic profile. A total of 279 MDR carbapenemase-producing K. pneumoniae from patients hospitalized all over Switzerland was investigated, and a rate of 9.0% K. pneumoniae presenting a virulence genotype was identified. Those isolates produced either KPC, NDM, or OXA-48 and had been either recovered from rectal swabs, urine, and blood. A series of previously reported K. pneumoniae clones such as ST23-K1, ST395-K2, and ST147-K20 or ST147-K64 were identified. All the isolates defined as MDR-hvKp (4.7%) possessed the aerobactin and the yersiniabactin clusters. The ST23-K1s were the only isolates presenting the colibactin cluster and achieved higher virulence scores. This study highlights the occurrence and circulation of worrisome MDR-hvKp and MDR nonhypervirulent K. pneumoniae (MDR-nhv-Kp) isolates in Switzerland. Our findings raise an alert regarding the need for active surveillance networks to track and monitor the spread of such successful hybrid clones representing a public health threat worldwide.
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Affiliation(s)
- Otávio Hallal Ferreira Raro
- Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Patrice Nordmann
- Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
- Swiss National Reference Center for Emerging Antibiotic Resistance (NARA), University of Fribourg, Fribourg, Switzerland
- Institute for Microbiology, University Hospital, Lausanne, Switzerland
| | - Manuel Dominguez Pino
- Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Jacqueline Findlay
- Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Laurent Poirel
- Medical and Molecular Microbiology, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
- Swiss National Reference Center for Emerging Antibiotic Resistance (NARA), University of Fribourg, Fribourg, Switzerland
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6
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Spadar A, Perdigão J, Campino S, Clark TG. Large-scale genomic analysis of global Klebsiella pneumoniae plasmids reveals multiple simultaneous clusters of carbapenem-resistant hypervirulent strains. Genome Med 2023; 15:3. [PMID: 36658655 PMCID: PMC9850321 DOI: 10.1186/s13073-023-01153-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/05/2023] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Klebsiella pneumoniae (Kp) Gram-negative bacteria cause nosocomial infections and rapidly acquire antimicrobial resistance (AMR), which makes it a global threat to human health. It also has a comparatively rare hypervirulent phenotype that can lead to severe disease in otherwise healthy individuals. Unlike classic Kp, canonical hypervirulent strains usually have limited AMR. However, after initial case reports in 2015, carbapenem-resistant hypervirulent Kp has increased in prevalence, including in China, but there is limited understanding of its burden in other geographical regions. METHODS Here, we examined the largest collection of publicly available sequenced Kp isolates (n=13,178), containing 1603 different sequence types (e.g. ST11 15.0%, ST258 9.5%), and 2174 (16.5%) hypervirulent strains. We analysed the plasmid replicons and carbapenemase and siderophore encoding genes to understand the movement of hypervirulence and AMR genes located on plasmids, and their convergence in carbapenem-resistant hypervirulent Kp. RESULTS We identified and analysed 3034 unique plasmid replicons to inform the epidemiology and transmission dynamics of carbapenem-resistant hypervirulent Kp (n=1028, 7.8%). We found several outbreaks globally, including one involving ST11 strains in China and another of ST231 in Asia centred on India, Thailand, and Pakistan. There was evidence of global flow of Kp, including across multiple continents. In most cases, clusters of Kp isolates are the result of hypervirulence genes entering classic strains, instead of carbapenem resistance genes entering canonical hypervirulent ones. CONCLUSIONS Our analysis demonstrates the importance of plasmid analysis in the monitoring of carbapenem-resistant and hypervirulent strains of Kp. With the growing adoption of omics-based technologies for clinical and surveillance applications, including in geographical regions with gaps in data and knowledge (e.g. sub-Saharan Africa), the identification of the spread of AMR will inform infection control globally.
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Affiliation(s)
- Anton Spadar
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - João Perdigão
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Susana Campino
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Taane G Clark
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
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7
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Opstrup KV, Bennike TB, Christiansen G, Birkelund S. Complement killing of clinical Klebsiella pneumoniae isolates is serum concentration dependent. Microbes Infect 2022; 25:105074. [PMID: 36336240 DOI: 10.1016/j.micinf.2022.105074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
Klebsiella pneumoniae is an opportunistic gram-negative pathogen causing serious infections, including sepsis. In plasma, activation of the complement cascades is important for killing bacteria. Thirty clinical Klebsiella spp. blood isolates were analyzed for serum susceptibility in 75% normal human serum (NHS). Twenty-two were serum resistant and eight were serum sensitive, and subsequently tested in 5-75% NHS. Two isolates were killed in 5% and the remaining six in 50%-75% NHS. The two 5% sensitive isolates showed binding of complement (C)4 and C3 in 5% NHS with formation of membrane attack complex (MAC). Inhibition of the classical/lectin mediated pathways (CP/LP) using a C4 specific nanobody, hC4Nb8, led to survival of both isolates in 5% NHS. Using nanobody hC3Nb1, inhibiting the alternative pathway (AP), the isolates were killed in 5% NHS, and amplification of the CP/LP by AP was not necessary for killing. Sole AP killing of these isolates when inhibiting CP/LP with hC4Nb8 was observed in 50% NHS, stressing the concentration dependent functionality of AP. For the less sensitive isolates, killing required activation of CP/LP and AP demonstrated by inhibition with nanobodies. AP inhibition resulted in no C3 deposition on the serum resistant isolate, supporting that AP was the sole activation pathway.
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Affiliation(s)
- Katharina V Opstrup
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Tue B Bennike
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Gunna Christiansen
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Svend Birkelund
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark.
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8
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Mackel JJ, Morffy Smith C, Wasbotten RK, Twentyman J, Rosen DA. Classical and γδ T cells are each independently sufficient to establish protection against a classical strain of Klebsiella pneumoniae. Front Cell Infect Microbiol 2022; 12:974175. [PMID: 36118033 PMCID: PMC9471189 DOI: 10.3389/fcimb.2022.974175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/11/2022] [Indexed: 11/20/2022] Open
Abstract
Infections with classical strains of the Gram-negative bacterium Klebsiella pneumoniae pose a significant clinical challenge due to rising antibiotic resistance. We previously established a lung inoculation plus challenge model using live, classical K. pneumoniae in order to study host protection. Here, we employ this model to dissect adaptive immune responses to this critical pathogen. First, we performed convalescent serum transfers from inoculated mice to naïve recipients and found that classical K. pneumoniae infection outcomes, unlike hypervirulent K. pneumoniae infection outcomes, were not improved. This suggests that circulating antibody responses alone are not sufficient to mediate protection against this classical strain. Hence, we evaluated the role of T cells in protection against classical K. pneumoniae reinfection and demonstrated that mice lacking T cells are unable to establish a protective response. However, mice individually deficient in either of the major T cell subsets, γδ or αβ (classical T cells), effectively mount a protective response, indicating either subset alone is sufficient to mediate protection. Sequestration of T cells in secondary lymphoid organs during the challenge infection did not ablate protection, indicating the circulating T cell pool is not required for the protective phenotype. Finally, we demonstrate that depletion of T cells during initial infection eliminates protection against challenge. Collectively, these experiments demonstrate the imperative contribution of T cells to protective immunity against classical K. pneumoniae and will guide further inquiries into host effector responses required to control this infection.
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Affiliation(s)
- Joseph J. Mackel
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - Catherine Morffy Smith
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - Rachel K. Wasbotten
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - Joy Twentyman
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
| | - David A. Rosen
- Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO, United States
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO, United States
- *Correspondence: David A. Rosen,
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9
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Spadar A, Perdigão J, Campino S, Clark TG. Genomic analysis of hypervirulent Klebsiella pneumoniae reveals potential genetic markers for differentiation from classical strains. Sci Rep 2022; 12:13671. [PMID: 35953553 PMCID: PMC9372168 DOI: 10.1038/s41598-022-17995-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 08/03/2022] [Indexed: 11/23/2022] Open
Abstract
The majority of Klebsiella pneumoniae (Kp) infections are nosocomial, but a growing number of community-acquired infections are caused by hypervirulent strains (hvKp) characterised by liver invasion and rapid metastasis. Unlike nosocomial Kp infections, hvKp are generally susceptible to antibiotics. Due to the rapid progression of hvKp infections, timely and accurate diagnosis is required for effective treatment. To identify potential drivers of the hypervirulent phenotype, we performed a genome-wide association study (GWAS) analysis on single nucleotide variants and accessory genome loci across 79 publicly available Kp isolates collected from patients’ liver and a diverse global Kp dataset (n = 646). The GWAS analysis revealed 29 putative genes (P < 10–10) associated with higher risk of liver phenotype, including hypervirulence linked salmochelin iro (odds ratio (OR): 29.8) and aerobactin iuc (OR: 14.1) loci. A minority of liver isolates (n = 15, 19%) had neither of these siderophores nor any other shared biomarker, suggesting possible unknown drivers of hypervirulence and an intrinsic ability of Kp to invade the liver. Despite identifying potential novel loci linked to a liver invasive Kp phenotype, our work highlights the need for large-scale studies involving more sequence types to identify further hypervirulence biomarkers to assist clinical decision making.
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Affiliation(s)
- Anton Spadar
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - João Perdigão
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Susana Campino
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Taane G Clark
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK. .,Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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10
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Leangapichart T, Lunha K, Jiwakanon J, Angkititrakul S, Järhult JD, Magnusson U, Sunde M. Characterization of Klebsiella pneumoniae complex isolates from pigs and humans in farms in Thailand: population genomic structure, antibiotic resistance and virulence genes. J Antimicrob Chemother 2021; 76:2012-2016. [PMID: 33829268 PMCID: PMC8283727 DOI: 10.1093/jac/dkab118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/14/2021] [Indexed: 11/15/2022] Open
Abstract
Objectives To define characteristics of Klebsiella pneumoniae complex (hereafter KP) isolates from healthy pigs, farm workers and their household members in Thailand. Methods A total of 839 individual rectal swabs from pigs on 164 farms and 271 faecal samples of humans working on pig farms and persons living in the same household in Khon Kaen, Thailand were screened for gut colonization by KP. Genomic sequences were investigated for antibiotic resistance and virulence genes. Phylogenetic analyses were performed in addition to comparison with isolates from previous studies from Thailand. Results KP was detected in approximately 50% of pig and human samples. In total, 253 KP isolates were obtained: 39% from pigs, 34% from farmers and 26% from individuals living on the same farm but without animal contact. MLST revealed high genetic diversity with 196 different STs distributed over four phylogroups (Kp1 to Kp4). Low prevalence of ESBL-KP (7.5%) and colistin-resistant KP (3.2%) was observed among pigs and humans. Remarkably, four convergent MDR and hypervirulent strains were observed: one from pigs (ST290) and three from humans [ST35, ST3415 (strain 90CP1), ST17 (strain 90CM2)]. Sharing of KP clones among pigs and humans was identified for some STs including ST4788, ST661, ST3541 and ST29. Conclusions The study indicated a low prevalence of ESBL and mcr genes among KP isolated from pigs and healthy humans in Thailand and suggested the possibility of zoonotic transmission for a subset of circulating KP clones.
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Affiliation(s)
- Thongpan Leangapichart
- Section for Food Safety and Animal Health Research, Department of Animal Health, Welfare and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
| | - Kamonwan Lunha
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jatesada Jiwakanon
- Research Group for Animal Health Technology, Khon Kaen University, Khon Kaen, Thailand
| | | | - Josef D Järhult
- Zoonosis Science Centre, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Ulf Magnusson
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Marianne Sunde
- Section for Food Safety and Animal Health Research, Department of Animal Health, Welfare and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
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11
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Blundell-Hunter G, Enright MC, Negus D, Dorman MJ, Beecham GE, Pickard DJ, Wintachai P, Voravuthikunchai SP, Thomson NR, Taylor PW. Characterisation of Bacteriophage-Encoded Depolymerases Selective for Key Klebsiella pneumoniae Capsular Exopolysaccharides. Front Cell Infect Microbiol 2021; 11:686090. [PMID: 34222050 PMCID: PMC8253255 DOI: 10.3389/fcimb.2021.686090] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/30/2021] [Indexed: 01/12/2023] Open
Abstract
Capsular polysaccharides enable clinically important clones of Klebsiella pneumoniae to cause severe systemic infections in susceptible hosts. Phage-encoded capsule depolymerases have the potential to provide an alternative treatment paradigm in patients when multiple drug resistance has eroded the efficacy of conventional antibiotic chemotherapy. An investigation of 164 K. pneumoniae from intensive care patients in Thailand revealed a large number of distinct K types in low abundance but four (K2, K51, K1, K10) with a frequency of at least 5%. To identify depolymerases with the capacity to degrade capsules associated with these common K-types, 62 lytic phage were isolated from Thai hospital sewage water using K1, K2 and K51 isolates as hosts; phage plaques, without exception, displayed halos indicative of the presence of capsule-degrading enzymes. Phage genomes ranged in size from 41-348 kb with between 50 and 535 predicted coding sequences (CDSs). Using a custom phage protein database we were successful in applying annotation to 30 - 70% (mean = 58%) of these CDSs. The largest genomes, of so-called jumbo phage, carried multiple tRNAs as well as CRISPR repeat and spacer sequences. One of the smaller phage genomes was found to contain a putative Cas type 1E gene, indicating a history of host DNA acquisition in these obligate lytic phage. Whole-genome sequencing (WGS) indicated that some phage displayed an extended host range due to the presence of multiple depolymerase genes; in total, 42 candidate depolymerase genes were identified with up to eight in a single genome. Seven distinct virions were selected for further investigation on the basis of host range, phage morphology and WGS. Candidate genes for K1, K2 and K51 depolymerases were expressed and purified as his6-tagged soluble protein and enzymatic activity demonstrated against K. pneumoniae capsular polysaccharides by gel electrophoresis and Anton-Paar rolling ball viscometry. Depolymerases completely removed the capsule in K-type-specific fashion from K. pneumoniae cells. We conclude that broad-host range phage carry multiple enzymes, each with the capacity to degrade a single K-type, and any future use of these enzymes as therapeutic agents will require enzyme cocktails for utility against a range of K. pneumoniae infections.
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Affiliation(s)
| | - Mark C. Enright
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
| | - David Negus
- School of Science & Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Matthew J. Dorman
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Gemma E. Beecham
- School of Pharmacy, University College London, London, United Kingdom
| | - Derek J. Pickard
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | | | | | - Nicholas R. Thomson
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, United Kingdom
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Peter W. Taylor
- School of Pharmacy, University College London, London, United Kingdom
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12
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Walker SS, Black TA. Are outer-membrane targets the solution for MDR Gram-negative bacteria? Drug Discov Today 2021; 26:2152-2158. [PMID: 33798647 DOI: 10.1016/j.drudis.2021.03.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/27/2021] [Accepted: 03/23/2021] [Indexed: 01/17/2023]
Abstract
The outer membrane (OM) of Gram-negative bacteria confers a significant barrier to many antibacterial agents targeting periplasmic and cytosolic functions. 'Synergist' approaches to disrupt the OM have been hampered by poor specificity and accompanying toxicities. The OM contains proteins required for optimal growth and pathogenesis, including lipopolysaccharide (LPS) and capsular polysaccharide (CPS) transport, porins for uptake of macromolecules, and transporters for essential elements (such as iron). Does the external proximity of these proteins offer an enhanced potential to identify effective therapies? Here, we review recent experiences in exploiting Gram-negative OM proteins (OMPs) to address the calamity of exploding antimicrobial resistance. Teaser: Multidrug-resistant (MDR) Gram-negative bacteria are a growing crisis. Few new antimicrobial chemotypes or targets have been identified after decades of screening. Are OMP targets a solution to MDR Gram-negative bacteria?
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Affiliation(s)
- Scott S Walker
- Infectious Diseases and Vaccines Basic Research, Merck & Co., Inc, 770 Sumneytown Pike, West Point, PA 19486, USA
| | - Todd A Black
- Infectious Diseases and Vaccines Basic Research, Merck & Co., Inc, 770 Sumneytown Pike, West Point, PA 19486, USA.
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13
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Majkowska-Skrobek G, Markwitz P, Sosnowska E, Lood C, Lavigne R, Drulis-Kawa Z. The evolutionary trade-offs in phage-resistant Klebsiella pneumoniae entail cross-phage sensitization and loss of multidrug resistance. Environ Microbiol 2021; 23:7723-7740. [PMID: 33754440 DOI: 10.1111/1462-2920.15476] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 03/11/2021] [Accepted: 03/18/2021] [Indexed: 12/18/2022]
Abstract
Bacteriophage therapy is currently being evaluated as a critical complement to traditional antibiotic treatment. However, the emergence of phage resistance is perceived as a major hurdle to the sustainable implementation of this antimicrobial strategy. By combining comprehensive genomics and microbiological assessment, we show that the receptor-modification resistance to capsule-targeting phages involves either escape mutation(s) in the capsule biosynthesis cluster or qualitative changes in exopolysaccharides, converting clones to mucoid variants. These variants introduce cross-resistance to phages specific to the same receptor yet sensitize to phages utilizing alternative ones. The loss/modification of capsule, the main Klebsiella pneumoniae virulence factor, did not dramatically impact population fitness, nor the ability to protect bacteria against the innate immune response. Nevertheless, the introduction of phage drives bacteria to expel multidrug resistance clusters, as observed by the large deletion in K. pneumoniae 77 plasmid containing blaCTX-M , ant(3″), sul2, folA, mph(E)/mph(G) genes. The emerging bacterial resistance to viral infection steers evolution towards desired population attributes and highlights the synergistic potential for combined antibiotic-phage therapy against K. pneumoniae.
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Affiliation(s)
- Grazyna Majkowska-Skrobek
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Wroclaw, Poland
| | - Pawel Markwitz
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Wroclaw, Poland
| | - Ewelina Sosnowska
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Wroclaw, Poland
| | - Cédric Lood
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, 3001 Heverlee, Belgium.,Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Laboratory of Computational Systems Biology, KU Leuven, 3000 Leuven, Belgium
| | - Rob Lavigne
- Department of Biosystems, Laboratory of Gene Technology, KU Leuven, 3001 Heverlee, Belgium
| | - Zuzanna Drulis-Kawa
- Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, University of Wroclaw, Wroclaw, Poland
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14
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Abstract
Klebsiella pneumoniae are Gram-negative facultative anaerobes that are found within host-associated commensal microbiomes, but they can also cause a wide range of infections that are often difficult to treat. These infections are caused by different pathotypes of K. pneumoniae, called either classical or hypervirulent strains. Klebsiella pneumoniae are Gram-negative facultative anaerobes that are found within host-associated commensal microbiomes, but they can also cause a wide range of infections that are often difficult to treat. These infections are caused by different pathotypes of K. pneumoniae, called either classical or hypervirulent strains. These two groups are genetically distinct, inhabit nonoverlapping geographies, and cause different types of harmful infections in humans. These distinct bacterial groups have also been found to interact differently with the host immune system. Initial innate immune defenses against K. pneumoniae infection include complement, macrophages, neutrophils, and monocytes; these defenses are primary strategies employed by the host to clear infections. K. pneumoniae pathogenesis depends upon the interactions between the microbe and each of these host defenses, and it is becoming increasingly apparent that bacterial genetic diversity impacts the outcomes of these interactions. Here, we highlight recent advances in our understanding of K. pneumoniae pathogenesis, with a focus on how bacterial evolution and diversity impact K. pneumoniae interactions with mammalian innate immune host defenses. We also discuss outstanding questions regarding how K. pneumoniae can frustrate normal immune responses, capitalize upon states of immunocompromise, and cause infections with high mortality.
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15
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Interplay between ESKAPE Pathogens and Immunity in Skin Infections: An Overview of the Major Determinants of Virulence and Antibiotic Resistance. Pathogens 2021; 10:pathogens10020148. [PMID: 33540588 PMCID: PMC7912840 DOI: 10.3390/pathogens10020148] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/16/2022] Open
Abstract
The skin is the largest organ in the human body, acting as a physical and immunological barrier against pathogenic microorganisms. The cutaneous lesions constitute a gateway for microbial contamination that can lead to chronic wounds and other invasive infections. Chronic wounds are considered as serious public health problems due the related social, psychological and economic consequences. The group of bacteria known as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) are among the most prevalent bacteria in cutaneous infections. These pathogens have a high level of incidence in hospital environments and several strains present phenotypes of multidrug resistance. In this review, we discuss some important aspects of skin immunology and the involvement of ESKAPE in wound infections. First, we introduce some fundamental aspects of skin physiology and immunology related to cutaneous infections. Following this, the major virulence factors involved in colonization and tissue damage are highlighted, as well as the most frequently detected antimicrobial resistance genes. ESKAPE pathogens express several virulence determinants that overcome the skin's physical and immunological barriers, enabling them to cause severe wound infections. The high ability these bacteria to acquire resistance is alarming, particularly in the hospital settings where immunocompromised individuals are exposed to these pathogens. Knowledge about the virulence and resistance markers of these species is important in order to develop new strategies to detect and treat their associated infections.
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16
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Innate Immune Effectors Play Essential Roles in Acute Respiratory Infection Caused by Klebsiella pneumoniae. J Immunol Res 2020; 2020:5291714. [PMID: 33163539 PMCID: PMC7607282 DOI: 10.1155/2020/5291714] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/16/2020] [Accepted: 10/12/2020] [Indexed: 12/24/2022] Open
Abstract
Innate immune effectors constitute the first line of host defense against pathogens. However, the roles of these effectors are not clearly defined during Klebsiella pneumoniae (K. pneumoniae) respiratory infection. In the current study, we established an acute pneumonia model of K. pneumoniae respiratory infection in mice and confirmed that the injury was most severe 48 h post infection. Flow cytometric assay demonstrated that alveolar macrophages were the predominant cells in BALF before infection, and neutrophils were quickly recruited after infection, and this was in consistent with the kinetics of chemokine expression. Further, we depleted neutrophils, macrophages, and complement pathways in vivo and challenged these mice with a sublethal dose of K. pneumonia, the result showed that 80%, 60%, and 40% of mice were died in these groups, respectively, while no deaths occurred in the control group. Besides, innate immune effector depleted mice showed higher bacterial burdens in lungs and blood, companied with more severe lung damage and increased levels of cytokine/chemokine expression. These results demonstrated that the innate immune effectors are critical in the early controlling of K. pneumoniae infection, and neutrophils are the most important. Thus, alternative strategies targeting these innate immune effectors may be effective in controlling of K. pneumoniae respiratory infection.
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17
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Genomic Profiling Reveals Distinct Routes To Complement Resistance in Klebsiella pneumoniae. Infect Immun 2020; 88:IAI.00043-20. [PMID: 32513855 PMCID: PMC7375759 DOI: 10.1128/iai.00043-20] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/28/2020] [Indexed: 12/19/2022] Open
Abstract
The serum complement system is a first line of defense against bacterial invaders. Resistance to killing by serum enhances the capacity of Klebsiella pneumoniae to cause infection, but it is an incompletely understood virulence trait. Identifying and characterizing the factors responsible for preventing activation of, and killing by, serum complement could inform new approaches to treatment of K. pneumoniae infections. Here, we used functional genomic profiling to define the genetic basis of complement resistance in four diverse serum-resistant K. pneumoniae strains (NTUH-K2044, B5055, ATCC 43816, and RH201207), and explored their recognition by key complement components. The serum complement system is a first line of defense against bacterial invaders. Resistance to killing by serum enhances the capacity of Klebsiella pneumoniae to cause infection, but it is an incompletely understood virulence trait. Identifying and characterizing the factors responsible for preventing activation of, and killing by, serum complement could inform new approaches to treatment of K. pneumoniae infections. Here, we used functional genomic profiling to define the genetic basis of complement resistance in four diverse serum-resistant K. pneumoniae strains (NTUH-K2044, B5055, ATCC 43816, and RH201207), and explored their recognition by key complement components. More than 90 genes contributed to resistance in one or more strains, but only three, rfaH, lpp, and arnD, were common to all four strains. Deletion of the antiterminator rfaH, which controls the expression of capsule and O side chains, resulted in dramatic complement resistance reductions in all strains. The murein lipoprotein gene lpp promoted capsule retention through a mechanism dependent on its C-terminal lysine residue; its deletion led to modest reductions in complement resistance. Binding experiments with the complement components C3b and C5b-9 showed that the underlying mechanism of evasion varied in the four strains: B5055 and NTUH-K2044 appeared to bypass recognition by complement entirely, while ATCC 43816 and RH201207 were able to resist killing despite being associated with substantial levels of C5b-9. All rfaH and lpp mutants bound C3b and C5b-9 in large quantities. Our findings show that, even among this small selection of isolates, K. pneumoniae adopts differing mechanisms and utilizes distinct gene sets to avoid complement attack.
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18
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Loraine J, Heinz E, Soontarach R, Blackwell GA, Stabler RA, Voravuthikunchai SP, Srimanote P, Kiratisin P, Thomson NR, Taylor PW. Genomic and Phenotypic Analyses of Acinetobacter baumannii Isolates From Three Tertiary Care Hospitals in Thailand. Front Microbiol 2020; 11:548. [PMID: 32328045 PMCID: PMC7153491 DOI: 10.3389/fmicb.2020.00548] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/13/2020] [Indexed: 12/24/2022] Open
Abstract
Antibiotic resistant strains of Acinetobacter baumannii are responsible for a large and increasing burden of nosocomial infections in Thailand and other countries of Southeast Asia. New approaches to their control and treatment are urgently needed and an attractive strategy is to remove the bacterial polysaccharide capsule, and thus the protection from the host's immune system. To examine phylogenetic relationships, distribution of capsule chemotypes, acquired antibiotic resistance determinants, susceptibility to complement and other traits associated with systemic infection, we sequenced 191 isolates from three tertiary referral hospitals in Thailand and used phenotypic assays to characterize key aspects of infectivity. Several distinct lineages were circulating in three hospitals and the majority belonged to global clonal group 2 (GC2). Very high levels of resistance to carbapenems and other front-line antibiotics were found, as were a number of widespread plasmid replicons. A high diversity of capsule genotypes was encountered, with only three of these (KL6, KL10, and KL47) showing more than 10% frequency. Almost 90% of GC2 isolates belonged to the most common capsule genotypes and were fully resistant to the bactericidal action of human serum complement, most likely protected by their polysaccharide capsule, which represents a key determinant of virulence for systemic infection. Our study further highlights the importance to develop therapeutic strategies to remove the polysaccharide capsule from extensively drug-resistant A. baumanii during the course of systemic infection.
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Affiliation(s)
- Jessica Loraine
- School of Pharmacy, University College London, London, United Kingdom
| | - Eva Heinz
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom.,Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom
| | | | - Grace A Blackwell
- Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom.,European Bioinformatics Institute, European Molecular Biology Laboratory, Hinxton, Cambridge, United Kingdom
| | - Richard A Stabler
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Potjanee Srimanote
- Faculty of Allied Health Sciences, Thammasat University, Pathumtanee, Thailand
| | | | - Nicholas R Thomson
- Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom.,London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Peter W Taylor
- School of Pharmacy, University College London, London, United Kingdom
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