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Sun Y, Wang L, Zhang M, Jie J, Guan Q, Fu J, Chu X, Chen D, Li C, Song L, Luo ZQ. Acinetobacter nosocomialis utilizes a unique type VI secretion system to promote its survival in niches with prey bacteria. mBio 2024; 15:e0146824. [PMID: 38916378 PMCID: PMC11253628 DOI: 10.1128/mbio.01468-24] [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: 05/20/2024] [Accepted: 06/10/2024] [Indexed: 06/26/2024] Open
Abstract
Pathogenic bacteria of the Acinetobacter genus pose a severe threat to human health worldwide due to their strong adaptability, tolerance, and antibiotic resistance. Most isolates of these bacteria harbor a type VI secretion system (T6SS) that allows them to outcompete co-residing microorganisms, but whether this system is involved in acquiring nutrients from preys remains less studied. In this study, we found that Ab25, a clinical isolate of Acinetobacter nosocomialis, utilizes a T6SS to kill taxonomically diverse microorganisms, including bacteria and fungi. The T6SS of Ab25 is constitutively expressed, and among the three predicted effectors, T6e1, a member of the RHS effector family, contributes the most for its antimicrobial activity. T6e1 undergoes self-cleavage, and a short carboxyl fragment with nuclease activity is sufficient to kill target cells via T6SS injection. Interestingly, strain Ab25 encodes an orphan VgrG protein, which when overexpressed blocks the firing of its T6SS. In niches such as dry plastic surfaces, the T6SS promotes prey microorganism-dependent survival of Ab25. These results reveal that A. nosocomialis employs T6SSs that are highly diverse in their regulation and effector composition to gain a competitive advantage in environments with scarce nutrient supply and competing microbes.IMPORTANCEThe type VI secretion system (T6SS) plays an important role in bacterial adaptation to environmental challenges. Members of the Acinetobacter genus, particularly A. baumannii and A. nosocomialis, are notorious for their multidrug resistance and their ability to survive in harsh environments. In contrast to A. baumannii, whose T6SS has been well-studied, few research works have focused on A. nosocomialis. In this study, we found that an A. nosocomialis strain utilizes a contitutively active T6SS to kill diverse microorganisms, including bacteria and fungi. Although T6SS structural proteins of A. nosocomialis are similar to those of A. baumannii, the effector repertoire differs greatly. Interestingly, the T6SS of the A. nosocomialis strain codes for an ophan VgrG protein, which blocks the firing of the system when overexpressed, suggesting the existence of a new regulatory mechanism for the T6SS. Importantly, although the T6SS does not provide an advantage when the bacterium is grown in nutrient-rich medium, it allows A. nosocomialis to survive better in dry surfaces that contain co-existing bacteria. Our results suggest that killing of co-residing microorganisms may increase the effectiveness of strategies designed to reduce the fitness of Acinetobacter bacteria by targeting their T6SS.
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Affiliation(s)
- Yu Sun
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
- Department of Gastroenterology, Endoscopy center, The First Hospital of Jilin University, Changchun, China
| | - Lidong Wang
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Ming Zhang
- Department of Ultrasound, The First Hospital of Jilin University, Changchun, China
| | - Jing Jie
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Qingtian Guan
- Bioinformatics Laboratory, The First Hospital of Jilin University, Changchun, China
| | - Jiaqi Fu
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Xiao Chu
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Dong Chen
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Chunxiuli Li
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Lei Song
- Department of Respiratory Medicine, Center of Infectious Diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, The First Hospital of Jilin University, Changchun, China
| | - Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
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Ham SY, Chun JY, Song KH, Kang CK, Park JS, Jo HB, Ryu CM, Choi Y, Choi SJ, Lee E, Choe PG, Moon SM, Park WB, Bang J, Park SW, Park KU, Kim NJ, Oh MD, Kim ES, Kim HB. Limited impact of bacterial virulence on early mortality risk factors in Acinetobacter baumannii bacteremia observed in a Galleria mellonella model. Sci Rep 2024; 14:14960. [PMID: 38942780 PMCID: PMC11213897 DOI: 10.1038/s41598-024-65940-2] [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: 04/02/2024] [Accepted: 06/25/2024] [Indexed: 06/30/2024] Open
Abstract
Acinetobacter baumannii (AB) has emerged as a major pathogen in vulnerable and severely ill patients. It remains unclear whether early mortality (EM) due to AB bacteremia is because of worse clinical characteristics of the infected patients or the virulence of the pathogen. In this study, we aimed to investigate the effect of AB virulence on EM due to bacteremia. This retrospective study included 138 patients with AB bacteremia (age: ≥ 18 years) who were admitted to a tertiary care teaching hospital in South Korea between 2015 and 2019. EM was defined as death occurring within 7 days of bacteremia onset. The AB clinical isolates obtained from the patients' blood cultures were injected into 15 Galleria mellonella larvae each, which were incubated for 5 days. Clinical isolates were classified into high- and low-virulence groups based on the number of dead larvae. Patients' clinical data were combined and subjected to multivariate Cox regression analyses to identify the risk factors for EM. In total, 48/138 (34.8%) patients died within 7 days of bacteremia onset. The Pitt bacteremia score was the only risk factor associated with EM. In conclusion, AB virulence had no independent effect on EM in patients with AB bacteremia.
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Affiliation(s)
- Sin Young Ham
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
- Department of Internal Medicine, Korea Veterans Hospital, Seoul, Republic of Korea
| | - June Young Chun
- Department of Internal Medicine, National Cancer Center, Goyang, Republic of Korea
| | - Kyoung-Ho Song
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chang Kyung Kang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jeong Su Park
- Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Hee Bum Jo
- Division of Infectious Diseases, Department of Internal Medicine, Incheon Sejong Hospital, Incheon, Republic of Korea
| | - Choong-Min Ryu
- Infection Disease Research Center, KRIBB, Daejeon, Republic of Korea
| | - Yunsang Choi
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
| | - Seong Jin Choi
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
| | - Eunyoung Lee
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Internal Medicine, Seoul Metropolitan Boramae Hospital, Seoul, Republic of Korea
| | - Pyoeng Gyun Choe
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Song Mi Moon
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Wan Beom Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jihwan Bang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Internal Medicine, Seoul Metropolitan Boramae Hospital, Seoul, Republic of Korea
| | - Sang-Won Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Internal Medicine, Seoul Metropolitan Boramae Hospital, Seoul, Republic of Korea
| | - Kyoung Un Park
- Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Nam Joong Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Myoung-Don Oh
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Eu Suk Kim
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea.
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
| | - Hong Bin Kim
- Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
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Manbenmad V, So-Ngern A, Chetchotisakd P, Faksri K, Ato M, Nithichanon A, Lertmemongkolchai G. Evaluating anti-GPL-core IgA as a diagnostic tool for non-tuberculous mycobacterial infections in Thai patients with high antibody background. Sci Rep 2023; 13:18883. [PMID: 37919326 PMCID: PMC10622420 DOI: 10.1038/s41598-023-45893-8] [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: 07/25/2023] [Accepted: 10/25/2023] [Indexed: 11/04/2023] Open
Abstract
Diagnosis of non-tuberculous mycobacterial (NTM) infection is difficult due to low sensitivity and time-consuming laboratory tests. Current serological assays fail in tropical countries due to high antibody background. This study aimed to investigate an appropriate method for detecting anti-glycopeptidolipid (GPL)-core antibodies to diagnose NTM infection in Thailand. Heparinized plasma samples were collected from 20 patients with NTM-pulmonary disease (NTM-PD) and 22 patients with disseminated NTM (dNTM) for antibody detection by ELISA. The results were compared with those from patients with tuberculosis, other bacterial pulmonary infections and healthy controls. Among the different antibody isotypes, anti-GPL-core IgA exhibited the highest suitability. Therefore, anti-GPL-core IgA and its subclass IgA2 were further investigated. A significant increase in antibody levels was observed during the active infection stage, whereas NTM-PD with culture conversion at the 6-month follow-up showed reduced IgA levels. The diagnostic cut-off for IgA and IgA2 was newly defined as 1.4 and 1.0 U/ml, respectively. Using our IgA cut-off, the sensitivity and specificity for diagnosing NTM-PD were 77.3% and 81.4%, respectively. The new IgA cut-off demonstrated significantly improved specificity compared to the manufacturer's cut-off. Thus, serological detection of anti-GPL-core IgA, with a cut-off of 1.4 U/ml, can be a valuable tool for supporting NTM diagnosis in Thailand.
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Affiliation(s)
- Varis Manbenmad
- Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Apichart So-Ngern
- Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | | | - Kiatichai Faksri
- Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Manabu Ato
- Department of Mycobacteriology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Arnone Nithichanon
- Research and Diagnostic Center for Emerging Infectious Diseases (RCEID), Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
| | - Ganjana Lertmemongkolchai
- Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
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Barrientos-Yong RS, Hinojosa-Salas BA, Salas-Ponce PG, Angles E, Ruiz J, Pons MJ. High rates of extensively drug-resistant Acinetobacter baumannii in a Peruvian hospital 2013–2019. Trop Doct 2022; 53:248-255. [PMID: 36518018 DOI: 10.1177/00494755221142939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Multidrug-resistant (MDR) Acinetobacter baumannii has become a major concern of hospital care. The objective of the study was to evaluate the evolution of antimicrobial resistance of A. baumannii in a Peruvian hospital from 2013 to 2019. A total of 993 A. baumannii clinical isolates were recovered. Antimicrobial resistance levels were extremely high, except for colistin. Among the remaining antibacterial agents, ampicillin plus sulbactam (AMS) was the most active (71.4% of resistance), with resistance levels to the remaining agents ranging from 75.9% to amikacin to 99.2% to ertapenem. The presence of significant differences was observed in extensively drug-resistant (XDR) A. baumannii according to samples origin. No association was observed between MDR or XDR isolates and seasonality. An impressive rate of XDR A. baumannii isolates was found, including a growing number of only-colistin-susceptible isolates highlighting the urgent need for new therapeutic alternatives.
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Affiliation(s)
| | | | - Percy Genaro Salas-Ponce
- Escuela de Medicina, Universidad Científica del Sur, Lima, Perú
- Hospital Nacional Arzobispo Loayza, Lima, Perú
| | | | - Joaquim Ruiz
- Laboratorio de Genética Molecular y Bioquímica, Universidad Científica del Sur, Lima, Perú
| | - Maria J Pons
- Laboratorio de Genética Molecular y Bioquímica, Universidad Científica del Sur, Lima, Perú
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