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Rao RSP, Ghate SD, Shastry RP, Kurthkoti K, Suravajhala P, Patil P, Shetty P. Prevalence and heterogeneity of antibiotic resistance genes in Orientia tsutsugamushi and other rickettsial genomes. Microb Pathog 2023; 174:105953. [PMID: 36529286 DOI: 10.1016/j.micpath.2022.105953] [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: 10/22/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 12/16/2022]
Abstract
Despite a million infections every year and an estimated one billion people at risk, scrub typhus is regarded as a neglected tropical disease. The causative bacterium Orientia tsutsugamushi, a member of rickettsiae, seems to be intrinsically resistant to several classes of antibiotics. The emergence of antibiotic-resistant scrub typhus is likely to become a global public health concern. Yet, it is unknown as to how common antibiotic resistance genes are in O. tsutsugamushi, and how variable these loci are among the genomes of rickettsiae. By using the comprehensive antibiotic resistance database, we explored 79 complete genomes from 24 species of rickettsiae for antibiotic resistance loci. There were 244 unique antibiotic resistance genes in rickettsiae. Both the total and unique antibiotic resistance genes in O. tsutsugamushi were significantly less compared to other members of rickettsiae. However, antibiotic resistance genes in O. tsutsugamushi genomes were more unique and highly variable. Many genes such as resistant variants of evgS, and vanS A/G were present in numerous copies. These results will have important implications in the context of antibiotic-resistant scrub typhus.
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Affiliation(s)
- R Shyama Prasad Rao
- Center for Bioinformatics, NITTE deemed to be University, Mangaluru, 575018, India.
| | - Sudeep D Ghate
- Center for Bioinformatics, NITTE deemed to be University, Mangaluru, 575018, India
| | - Rajesh P Shastry
- Division of Microbiology and Biotechnology, Yenepoya Research Center, Yenepoya deemed to be University, Mangaluru, 575018, India
| | - Krishna Kurthkoti
- Mycobacterium Research Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, 695014, India
| | - Prashanth Suravajhala
- Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Clappana PO, 690525, Kerala, India
| | - Prakash Patil
- Central Research Laboratory, KS Hegde Medical Academy (KSHEMA), NITTE deemed to be University, Mangaluru, 575018, India
| | - Praveenkumar Shetty
- Central Research Laboratory, KS Hegde Medical Academy (KSHEMA), NITTE deemed to be University, Mangaluru, 575018, India; Department of Biochemistry, KS Hegde Medical Academy (KSHEMA), NITTE deemed to be University, Mangaluru, 575018, India
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Orientia tsutsugamushi Is Highly Susceptible to the RNA Polymerase Switch Region Inhibitor Corallopyronin A In Vitro and In Vivo. Antimicrob Agents Chemother 2018; 62:AAC.01732-17. [PMID: 29358295 DOI: 10.1128/aac.01732-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/12/2018] [Indexed: 01/19/2023] Open
Abstract
Scrub typhus is a potentially lethal infection caused by the obligate intracellular bacterium Orientia tsutsugamushi Reports on the emergence of doxycycline-resistant strains highlight the urgent need to develop novel antiinfectives against scrub typhus. Corallopyronin A (CorA) is a novel α-pyrone compound synthesized by the myxobacterium Corallococcus coralloides that was characterized as a noncompetitive inhibitor of the switch region of the bacterial RNA polymerase (RNAP). We investigated the antimicrobial action of CorA against the human-pathogenic Karp strain of O. tsutsugamushiin vitro and in vivo The MIC of CorA against O. tsutsugamushi was remarkably low (0.0078 μg/ml), 16-fold lower than that against Rickettsia typhi In the lethal intraperitoneal O. tsutsugamushi mouse infection model, a minimum daily dose of 100 μg CorA protected 100% of infected mice. Two days of treatment were sufficient to confer protection. In contrast to BALB/c mice, SCID mice succumbed to the infection despite treatment with CorA or tetracycline, suggesting that antimicrobial treatment required synergistic action of the adaptive immune response. Similar to tetracycline, CorA did not prevent latent infection of O. tsutsugamushiin vivo However, latency was not caused by acquisition of antimicrobial resistance, since O. tsutsugamushi reisolated from latently infected BALB/c mice remained fully susceptible to CorA. No mutations were found in the CorA-binding regions of the β and β' RNAP subunit genes rpoB and rpoC Inhibition of the RNAP switch region of O. tsutsugamushi by CorA is therefore a novel and highly potent target for antimicrobial therapy for scrub typhus.
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Affiliation(s)
- Munegowda C Koralur
- 1 Lecturer, Department of Microbiology, Kasturba Medical College, Manipal University, Manipal, India.,2 Present address: Biotechnology Applications Laboratory, Division of Vector Borne Diseases, NCEZID, CDC, Atlanta, GA, USA
| | - Rahul Singh
- 3 Student, Kasturba Medical College, Manipal, India
| | - Muralidhar Varma
- 4 Associate Professor, Department of Medicine, Kasturba Medical College, Manipal University, Manipal, India
| | - John Stenos
- 5 Associate Professor/Director, Australian Rickettsial Reference Laboratory, Geelong, VIC, Australia
| | - Indira Bairy
- 6 Professor, Department of Microbiology, Melaka Manipal Medical College, Manipal Campus, Manipal University, Manipal, India
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Bonell A, Lubell Y, Newton PN, Crump JA, Paris DH. Estimating the burden of scrub typhus: A systematic review. PLoS Negl Trop Dis 2017; 11:e0005838. [PMID: 28945755 PMCID: PMC5634655 DOI: 10.1371/journal.pntd.0005838] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 10/10/2017] [Accepted: 07/28/2017] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Scrub typhus is a vector-borne zoonotic disease that can be life-threatening. There are no licensed vaccines, or vector control efforts in place. Despite increasing awareness in endemic regions, the public health burden and global distribution of scrub typhus remains poorly known. METHODS We systematically reviewed all literature from public health records, fever studies and reports available on the Ovid MEDLINE, Embase Classic + Embase and EconLit databases, to estimate the burden of scrub typhus since the year 2000. FINDINGS In prospective fever studies from Asia, scrub typhus is a leading cause of treatable non-malarial febrile illness. Sero-epidemiological data also suggest that Orientia tsutsugamushi infection is common across Asia, with seroprevalence ranging from 9.3%-27.9% (median 22.2% IQR 18.6-25.7). A substantial apparent rise in minimum disease incidence (median 4.6/100,000/10 years, highest in China with 11.2/100,000/10 years) was reported through passive national surveillance systems in South Korea, Japan, China, and Thailand. Case fatality risks from areas of reduced drug-susceptibility are reported at 12.2% and 13.6% for South India and northern Thailand, respectively. Mortality reports vary widely around a median mortality of 6.0% for untreated and 1.4% for treated scrub typhus. Limited evidence suggests high mortality in complicated scrub typhus with CNS involvement (13.6% mortality), multi-organ dysfunction (24.1%) and high pregnancy miscarriage rates with poor neonatal outcomes. INTERPRETATION Scrub typhus appears to be a truly neglected tropical disease mainly affecting rural populations, but increasingly also metropolitan areas. Rising minimum incidence rates have been reported over the past 8-10 years from countries with an established surveillance system. A wider distribution of scrub typhus beyond Asia is likely, based on reports from South America and Africa. Unfortunately, the quality and quantity of the available data on scrub typhus epidemiology is currently too limited for any economical, mathematical modeling or mapping approaches.
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Affiliation(s)
- Ana Bonell
- Oxford University Clinical Research Unit, National Hospital of Tropical Diseases, Hanoi, Vietnam
| | - Yoel Lubell
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Paul N. Newton
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - John A. Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Daniel H. Paris
- Mahidol Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Faculty of Medicine, University Basel, Basel, Switzerland
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Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is responsible for more than one million cases of scrub typhus annually throughout the Asia-Pacific region. Human infection occurs via the bite of the larval form (chigger) of several species of trombiculid mites. While in some patients the result of infection is a mild, febrile illness, others experience severe complications, which may even be fatal. This review discusses the genome and biology of the causative agent, the changing epidemiology of scrub typhus, the challenges of its diagnosis, and current treatment recommendations.
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Affiliation(s)
- Sunil Thomas
- Lankenau Institute for Medical Research, Wynnewood, Pennsylvania USA
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Petrova ES. Injured Nerve Regeneration using Cell-Based Therapies: Current Challenges. Acta Naturae 2015; 7:38-47. [PMID: 26483958 PMCID: PMC4610163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This paper reviews the recent research progress in the past several years on promoting peripheral nerve recovery using stem and progenitory cells. The emphasis is placed on studies aimed at assessing various stem cells capable of expressing neurotrophic and growth factors and surviving after implantation in the nerve or a conduit. Approaches to improving nerve conduit design are summarized. The contribution of stem cells to axonal regeneration and neural repair is discussed. The side effects associated with cell-based treatment are highlighted. From the studies reviewed, it is concluded that the fate of transplanted stem cells needs further elucidation in a microenvironment-dependent manner.
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Affiliation(s)
- E. S. Petrova
- Federal State Budgetary Scientific Institution «Institute of Experimental Medicine», St. Petersburg, Akad. Pavlov str.,12, 197376, Russia
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Lee OH, Baek JH, Lee JS, Chung MH, Lee SM, Kang JS. In vitro Antagonism between Cefotaxime and Anti-Rickettsial Antibiotics against Orientia tsutsugamushi. Infect Chemother 2014; 46:189-93. [PMID: 25298908 PMCID: PMC4189142 DOI: 10.3947/ic.2014.46.3.189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 06/18/2014] [Accepted: 06/18/2014] [Indexed: 11/24/2022] Open
Abstract
We have investigated the in vitro antimicrobial effects of antibiotic combinations against Orientia tsutsugamushi, the causative agent of scrub typhus. ECV304 cells were infected with the Boryong strain of O. tsutsugamushi and incubated in a medium containing doxycycline (4 µg/mL), azithromycin (0.5 µg/mL), rifampin (4 µg/mL), ciprofloxacin (25 µg/mL), gentamicin (5 µg/mL), cefotaxime (2 µg/mL), or combinations of these agents for 7 days, after which immunofluorescent staining for O. tsutsugamushi was performed. The percentages of infective foci in cultures containing antibiotics compared to those in cultures without antibiotics were 6.2% for doxycycline, 9.6% for azithromycin, 8.8% for rifampin, 96.6% for cefotaxime, 29.7% for doxycycline plus cefotaxime, 23.6% for azithromycin plus cefotaxime, and 41.4% for rifampin plus cefotaxime. These findings show an in vitro antagonism between anti-rickettsial agents and cefotaxime against O. tsutsugamushi. These results suggest that the efficacy of antibiotic combinations involving cefotaxime for the treatment of patients with scrub typhus, particularly those with severe pneumonia, needs to be investigated.
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Affiliation(s)
- Oh Hyun Lee
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
| | - Ji Hyeon Baek
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
| | - Jin-Soo Lee
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
| | - Moon-Hyun Chung
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
| | - Sun Myoung Lee
- Translation Research Center, Inha University School of Medicine, Incheon, Korea
| | - Jae-Seung Kang
- Department of Microbiology, Inha University School of Medicine, Incheon, Korea
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Son D, Chung MH. In vitro Synergism between Chloroquine and Antibiotics against Orientia tsutsugamushi. Infect Chemother 2014; 46:182-8. [PMID: 25298907 PMCID: PMC4189136 DOI: 10.3947/ic.2014.46.3.182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/12/2014] [Accepted: 09/12/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND To investigate whether chloroquine enhances the effect of antibiotics against Orientia tsutsugamushi, the causative organism of scrub typhus, we compared the effect of antibiotics in combination with chloroquine with the effect of antibiotics alone in vitro. MATERIALS AND METHODS The Boryong or AFSC-4 strain was inoculated into ECV304 cells, and incubated in medium containing doxycycline (4 µg/mL), rifampin (4 µg/mL), azithromycin (0.5 µg/mL), chloroquine (1 µg/mL), and each of these antibiotics in combination with chloroquine for 7 d. Immunofluorescence (IF) staining for O. tsutsugamushi was performed 4 hr and 7 d after inoculation of the bacteria, and IF-positive foci were enumerated. RESULTS Chloroquine inhibited the growth of O. tsutsugamushi by 15.5%. In combination with chloroquine, the antimicrobial effects increased by 4.4% for doxycycline (a 92.9% reduction of bacterial numbers for doxycycline versus a 97.3% reduction for doxycycline plus chloroquine), 4.6% for rifampin (90.0% versus 94.6%), and 8.3% for azithromycin (86.9% versus 95.2%). The antimicrobial effect of the antibiotics alone was significantly different compared to the combined effect of antibiotics and chloroquine (Wilcoxon signed-rank test, P = 0.001). CONCLUSIONS The combined use of chloroquine with an antibiotic for the treatment of O. tsutsugamushi infections may be useful for increasing the efficacy of the antibiotics.
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Affiliation(s)
- Dongwook Son
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
| | - Moon-Hyun Chung
- Department of Internal Medicine, Inha University School of Medicine, Incheon, Korea
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Kim J. Is ambient air pollution another risk factor of tuberculosis? Korean J Intern Med 2014; 29:170-2. [PMID: 24648798 PMCID: PMC3956985 DOI: 10.3904/kjim.2014.29.2.170] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 02/22/2014] [Indexed: 01/26/2023] Open
Affiliation(s)
- Jusang Kim
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea
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