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Azimi L, Hasani H, Karimi A, Fahimzad SA, Fallah F, Fatehi S, Armin S, Sadr M. Characterization of genes involved in the iron acquisition system of multidrug-resistant Acinetobacter baumannii. GMS HYGIENE AND INFECTION CONTROL 2024; 19:Doc25. [PMID: 38883402 PMCID: PMC11177110 DOI: 10.3205/dgkh000480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Background The high prevalence of virulence-associated genes observed in Acinetobacter baumannii isolates underscores the pathogenic potential of this bacterium. The presence of these genes confers enhanced survival, evasion of host defenses, and increased virulence. In this study, we investigate the presence and distribution of genes associated with virulence and assess the antimicrobial susceptibility patterns in clinical isolates of A. baumannii. Materials and method This research focused on examining the 50 multi-drugs resistant (MDR) strains that were included in this investigation. The identification of these strains was validated using Oxa-51. The presence of the BauA and BasD genes was determined through conventional PCR techniques. Results The results derived from Oxa-51 PCR confirmed the identification of all 50 selected strains of A. baumannii. Additionally, both the BauA and BasD genes were successfully identified in 82% of the MDR strains. Conclusion Moreover, the varying antibiotic resistance patterns highlight the challenge in treating A. baumannii infections effectively. Strategies such as combination therapy, antimicrobial stewardship, and infection control measures should be considered to combat this multidrug-resistant pathogen.
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Affiliation(s)
- Leila Azimi
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hadi Hasani
- Department of Medical Surgical Nursing, Jovein School of Nursing, Sabzevar University of Medical Sciences, Sabzevar, Iran
| | - Abdollah Karimi
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Alireza Fahimzad
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Fallah
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shima Fatehi
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahnaz Armin
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammadreza Sadr
- Department of Pediatrics, School of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran
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Zheng C, Li D, Wang Y, Wang L, Huang Y, Yao J. Risk factors and genetic characteristics of the carriage of hypervirulent and carbapenem-resistant Acinetobacter baumannii among pregnant women. Front Microbiol 2024; 15:1351722. [PMID: 38572236 PMCID: PMC10987950 DOI: 10.3389/fmicb.2024.1351722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/16/2024] [Indexed: 04/05/2024] Open
Abstract
Background Carbapenem-resistant Acinetobacter baumannii (CRAB) and its emerging evolutionary branch toward hypervirulence have been neglected in pregnancy. Methods From September 2020 to August 2021, an active surveillance culture program encompassed 138 randomly selected pregnant women, with five subjected to sample collection at two different time points. The clinical characterization was explored through statistical analysis. Whole-genome sequencing, a Galleria mellonella infection model, and a global database were used to investigate the genetic characterization, pathogenicity, evolutionary history, and phylogenetic relationships of the isolates. Results Of the 41 CRAB isolates obtained, they were divided into four ClustersRS and an orphan pattern. ClusterRS 1 (n = 31), with eight complex types in pregnancy, was also the dominant ClusterRS globally, followed by ClusterRS 13 (n = 5), identified as hypervirulent KL49 CRAB, exhibiting phylogeographical specificity to Guangdong. A maternal carriage CRAB rate of 26.09% (36/138) was revealed, with half of the isolates representing novel complex types, prominently including CT3071, as the first KL7 isolates identified in Shenzhen. Both KL49 and KL7 isolates were most commonly found in the same participant, suggesting potential intraspecific competition as a possible reason for CRAB infection without carriers during pregnancy. The independent risk factors for carriers were revealed for the first time, including advanced maternal age, gestational diabetes mellitus, and Group B Streptococcus infection. Conclusion The significant carriage rate and enhanced virulence of CRAB during pregnancy emphasize the imperative for routine surveillance to forestall dissemination within this high-risk group, especially in Guangdong for ClusterRS 13 isolates.
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Affiliation(s)
- Chao Zheng
- Department of Gastroenterology, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
- Bacteriology and Antibacterial Resistance Surveillance Laboratory, Shenzhen Institute of Respiratory Disease, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
- Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, China
- School of Materials and Environmental Engineering, Shenzhen Polytechnic University, Shenzhen, China
| | - Defeng Li
- Department of Gastroenterology, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
| | - Yinglan Wang
- Department of Obstetrics and Gynecology, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
| | - Lisheng Wang
- Department of Gastroenterology, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
| | - Yuting Huang
- Bacteriology and Antibacterial Resistance Surveillance Laboratory, Shenzhen Institute of Respiratory Disease, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
- Department of Head and Neck Surgery, Cancer Hospital Chinese Academy of Medical Sciences Shenzhen Center, Shenzhen, China
| | - Jun Yao
- Department of Gastroenterology, Shenzhen People’s Hospital (The Second Clinical Medical College of Jinan University, The First Affiliated Hospital of Southern University of Science and Technology), Shenzhen, China
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Zhou J, Feng D, Li X, Chen Y, Zhang M, Wu W, Zhu J, Li H, Peng X, Zhang T. L-Serine enables reducing the virulence of Acinetobacter baumannii and modulating the SIRT1 pathway to eliminate the pathogen. Microbiol Spectr 2024; 12:e0322623. [PMID: 38240573 PMCID: PMC10913490 DOI: 10.1128/spectrum.03226-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 11/14/2023] [Indexed: 03/07/2024] Open
Abstract
The emergence of high-virulent Acinetobacter baumannii strains increases the mortality of patients and seriously affects their prognosis, which motivates us to explore novel ways to control such infections. In this study, gas chromatography-mass spectrometry was adopted to explore the metabolic difference between high- and low-virulent A. baumannii strains, and the decreased L-serine levels were identified as the most crucial biomarker in low-virulent A. baumannii strains. In vitro, L-serine reduced the virulence of A. baumannii to Beas 2B cells and inhibited the activation of NLRP3 inflammasome via decreasing the generation of ROS and mtROS and the release of inflammatory cytokines (IL-18 and IL-1β) through upregulating SIRT1. In vivo, the Galleria mellonella model was adopted. L-serine downregulated the levels of virulence genes (ompA, carO, and omp33-36), reduced the mortality of A. baumannii to G. mellonella, and decreased the blacking speed as well as the degree of G. mellonella after infection. Taken together, we found that L-serine can reduce the virulence of A. baumannii and enhance the host's defense against the pathogen, providing a novel strategy for the treatment of infections caused by A. baumannii.IMPORTANCEAcinetobacter baumannii has become one of the most common and severe opportunistic pathogens in hospitals. The high-virulent A. baumannii strains pose a great threat to patients and increase the risk of nosocomial infection. However, the mechanism of virulence in A. baumannii is still not well understood. In the present study, we identified potential biomarkers in low-virulent A. baumannii strains. Our analysis revealed the effect of L-serine on reducing the virulence of A.baumannii. This discovery suggests that targeting L-serine could be a promising strategy for the treatment or adjunctive treatment of A. baumannii infections. The development of treatments targeting virulence may provide a substitute for the increasingly failed traditional antibacterial treatment.
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Affiliation(s)
- Jianxia Zhou
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Dingyun Feng
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Xia Li
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Yuetao Chen
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Min Zhang
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Wenbin Wu
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Jiaxin Zhu
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Hui Li
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Xuanxian Peng
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Tiantuo Zhang
- Department of Pulmonary and Critical Care Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Institute of Respiratory Disease of Sun Yat-Sen University, Guangzhou, People's Republic of China
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Pai L, Patil S, Liu S, Wen F. A growing battlefield in the war against biofilm-induced antimicrobial resistance: insights from reviews on antibiotic resistance. Front Cell Infect Microbiol 2023; 13:1327069. [PMID: 38188636 PMCID: PMC10770264 DOI: 10.3389/fcimb.2023.1327069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 11/20/2023] [Indexed: 01/09/2024] Open
Abstract
Biofilms are a common survival strategy employed by bacteria in healthcare settings, which enhances their resistance to antimicrobial and biocidal agents making infections difficult to treat. Mechanisms of biofilm-induced antimicrobial resistance involve reduced penetration of antimicrobial agents, increased expression of efflux pumps, altered microbial physiology, and genetic changes in the bacterial population. Factors contributing to the formation of biofilms include nutrient availability, temperature, pH, surface properties, and microbial interactions. Biofilm-associated infections can have serious consequences for patient outcomes, and standard antimicrobial therapies are often ineffective against biofilm-associated bacteria, making diagnosis and treatment challenging. Novel strategies, including antibiotics combination therapies (such as daptomycin and vancomycin, colistin and azithromycin), biofilm-targeted agents (such as small molecules (LP3134, LP3145, LP4010, LP1062) target c-di-GMP), and immunomodulatory therapies (such as the anti-PcrV IgY antibodies which target Type IIIsecretion system), are being developed to combat biofilm-induced antimicrobial resistance. A multifaceted approach to diagnosis, treatment, and prevention is necessary to address this emerging problem in healthcare settings.
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Affiliation(s)
- Liu Pai
- Department of Hematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, China
- Pediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, China
| | - Sandip Patil
- Department of Hematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, China
- Pediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, China
| | - Sixi Liu
- Department of Hematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, China
| | - Feiqiu Wen
- Department of Hematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, China
- Pediatric Research Institute, Shenzhen Children’s Hospital, Shenzhen, China
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Wei C, Chen J, Anwar TM, Huang L, Yang W, Dong X, Chen Q, Yue M, Yu D. Genomic Determinants of Pathogenicity and Antimicrobial Resistance of Nosocomial Acinetobacter baumannii Clinical Isolates of Hospitalized Patients (2019-2021) from a Sentinel Hospital in Hangzhou, China. Infect Drug Resist 2023; 16:2939-2952. [PMID: 37201122 PMCID: PMC10187652 DOI: 10.2147/idr.s407577] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/29/2023] [Indexed: 05/20/2023] Open
Abstract
Purpose Acinetobacter baumannii (A. baumannii or AB) is one of the most opportunistic, nosocomial pathogens threatening public healthcare across countries. A. baumannii has become a primary growing concern due to its exceptional ability to acquire antimicrobial resistance (AMR) to multiple antimicrobial agents which is increasingly reported and more prevalent every year. Therefore, there is an urgent need to evaluate the AMR knowledge of A. baumannii for effective clinical treatment of nosocomial infections. This study aimed to investigate the clinical distribution AMR phenotypes and genotypes, and genomic characteristics of A. baumannii isolates recovered from hospitalized patients of different clinical departments of a sentinel hospital to improve clinical practices. Methods A total of 123 clinical isolates were recovered from hospitalized patients of different clinical departments during 2019-2021 to analyze AMR patterns, and further subjected to whole-genome sequencing (WGS) investigations. Multi-locus sequence typing (MLST), as well as the presence of antimicrobial-resistant genes (ARGs), virulence factor genes (VFGs) and insertion sequences (ISs) were also investigated from WGS data. Results The results highlighted that A. baumannii clinical isolates had shown a high AMR rate, particularly from the intensive care unit (ICU), towards routinely used antimicrobials, ie, β-lactams and fluoroquinolones. ST2 was the most prevalent ST in the clinical isolates, it was strongly associated to the resistance of cephalosporins and carbapenems, with blaOXA-23 and blaOXA-66 being the most frequent determinants; moreover, high carrier rate of VFGs was also observed such as all strains containing the ompA, adeF, pgaC, lpsB, and bfmR genes. Conclusion Acinetobacter baumannii clinical isolates are mostly ST2 with high rates of drug resistance and carrier of virulence factors. Therefore, it requires measurements to control its transmission and infection.
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Affiliation(s)
- Chenxing Wei
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
| | - Jian Chen
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
| | - Tanveer Muhammad Anwar
- Department of Veterinary Medicine, Institute of Preventive Veterinary Sciences, Zhejiang University College of Animal Sciences, Hangzhou, 310058, People’s Republic of China
| | - Lingling Huang
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
| | - Wenjie Yang
- Department of Medical Laboratory, The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, People’s Republic of China
| | - Xueyan Dong
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
| | - Qiong Chen
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
| | - Min Yue
- Department of Veterinary Medicine, Institute of Preventive Veterinary Sciences, Zhejiang University College of Animal Sciences, Hangzhou, 310058, People’s Republic of China
- Hainan Institute, Zhejiang University, Sanya, 572025, People’s Republic of China
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, National Medical Center for Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, People’s Republic of China
- Correspondence: Min Yue; Daojun Yu, Email ;
| | - Daojun Yu
- Department of Medical Laboratory, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, People’s Republic of China
- Department of Medical Laboratory, The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, 310053, People’s Republic of China
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Kim SE, Choi SM, Yu Y, Shin SU, Oh TH, Kang SJ, Park KH, Shin JH, Kim UJ, Jung SI. Replacement of the Dominant ST191 Clone by ST369 Among Carbapenem-Resistant Acinetobacter baumannii Bloodstream Isolates at a Tertiary Care Hospital in South Korea. Front Microbiol 2022; 13:949060. [PMID: 35910596 PMCID: PMC9335038 DOI: 10.3389/fmicb.2022.949060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
The clonal dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia is a serious clinical problem worldwide. However, the factors related to the emergence and replacement of predominant CRAB clones in nosocomial settings are unclear. By multilocus sequence typing (MLST), we evaluated the genetic relatedness of CRAB bloodstream isolates at a tertiary care hospital over a 3.5-year period and investigated the clinical and microbiologic characteristics of the predominant sequence types (STs). One hundred and seventy-nine CRAB bloodstream isolates were collected from June 2016 to December 2019, and their MLSTs according to Oxford scheme and clinical data were obtained. The predominant STs were assessed for in vitro growth, competitive growth, and virulence in a mouse model of intraperitoneal infection. Two dominant clones—ST369 (n = 98) and ST191 (n = 48)—belonging to international clone 2 (IC2) were recovered from patients admitted to intensive care units (ICUs) or wards. ST191 predominated (61%, 27/43) from June 2016 to July 2017, whereas ST369 (72%, 98/136), which was first isolated from a patient admitted to the emergency room, replaced ST191 (15%, 21/136) after August 2017. In a multivariate analysis, leukopenia (OR = 3.62, 95% CI 1.04–12.6, p = 0.04) and ST191 or 369 (OR = 5.32, 95% CI 1.25–22.65, p = 0.02) were independent risk factors for 7-day mortality. Compared with non-ST369, ST369 was associated with a shorter time to bacteremia from ICU admission (7 vs. 11 days, p = 0.01), pneumonia as an origin of bacteremia (67 vs. 52%, p = 0.04), leukopenia (28 vs. 11%, p < 0.01), and a lower 7-day survival rate (41 vs. 70%, p < 0.01). In vitro, ST 369 isolates had significantly higher growth rates and enhanced competitive growth compared to ST191. Finally, ST369 had greater virulence and a higher mortality rate than other STs in a mouse infection model. We report almost-complete replacement of the predominant ST191 clone by ST369 within an 8-month period at our hospital. ST369 had a high incidence density rate of CRAB bacteremia, a short time to bacteremia after ICU admission, and a high early mortality rate, which may be in part explained by its faster competitive growth rate and higher virulence than ST191.
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Affiliation(s)
- Seong Eun Kim
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Su-Mi Choi
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Yohan Yu
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Sung Un Shin
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Tae Hoon Oh
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Seung-Ji Kang
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Kyung-Hwa Park
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
| | - Jong Hee Shin
- Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, South Korea
| | - Uh Jin Kim
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
- Uh Jin Kim,
| | - Sook In Jung
- Department of Infectious Diseases, Chonnam National University Medical School, Gwangju, South Korea
- *Correspondence: Sook In Jung,
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Ding Z, Li Z, Zhao Y, Hao J, Li T, Liu Y, Zeng Z, Liu J. Phenotypic and Genotypic Characteristics of a Tigecycline-Resistant Acinetobacter pittii Isolate Carrying bla NDM-1 and the Novel bla OXA Allelic Variant bla OXA-1045. Front Microbiol 2022; 13:868152. [PMID: 35602052 PMCID: PMC9116503 DOI: 10.3389/fmicb.2022.868152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/30/2022] [Indexed: 11/13/2022] Open
Abstract
A tigecycline-resistant Acinetobacter pittii clinical strain from pleural fluid carrying a blaNDM–1 gene and a novel blaOXA gene, blaOXA–1045, was isolated and characterized. The AP2044 strain acquired two copies of the blaNDM–1 gene and six antibiotic resistance genes (ARGs) from other pathogens. According to the whole-genome investigation, the GC ratios of ARGs (50–60%) were greater than those of the chromosomal backbone (39.46%), indicating that ARGs were horizontally transferred. OXA-1045 belonged to the OXA-213 subfamily and the amino acid sequence of OXA-1045 showed 89% similarity to the amino acid sequences of OXA-213. Then, blaOXA–1045 and blaOXA–213 were cloned and the minimum inhibitory concentrations (MICs) of β-lactams in the transformants were determined using the broth microdilution method. OXA-1045 was able to confer a reduced susceptibility to piperacillin and piperacillin-tazobactam compared to OXA-213. AP2044 strain exhibited low pathogenicity in Galleria mellonella infection models. The observation of condensed biofilm using the crystal violet staining method and scanning electron microscopy (SEM) suggested that the AP2044 strain was a weak biofilm producer. Quantitative reverse transcription-PCR (qRT-PCR) was used to detect the expression of resistance-nodulation-cell division (RND) efflux pump-related genes. The transcription level of adeB and adeJ genes increased significantly and was correlated with tigecycline resistance. Therefore, our genomic and phenotypic investigations revealed that the AP2044 strain had significant genome plasticity and natural transformation potential, and the emergence of antibiotic resistance in these unusual bacteria should be a concern for future investigations.
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Affiliation(s)
- Zixuan Ding
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Zhaoyinqian Li
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Yuanqing Zhao
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Jingchen Hao
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Tingting Li
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Yao Liu
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Zhangrui Zeng
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Jinbo Liu
- Department of Laboratory Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou, China
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Synergistic Inhibitory Effect of Polymyxin B in Combination with Ceftazidime against Robust Biofilm Formed by Acinetobacter baumannii with Genetic Deficiency in AbaI/AbaR Quorum Sensing. Microbiol Spectr 2022; 10:e0176821. [PMID: 35196792 PMCID: PMC8865539 DOI: 10.1128/spectrum.01768-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Carbapenem resistance of Acinetobacter baumannii poses challenges to public health. Biofilm contributes to the persistence of A. baumannii cells. This study was designed to investigate the genetic relationships among carbapenem resistance, polymyxin resistance, multidrug resistance, biofilm formation, and surface-associated motility and evaluate the antibiofilm effect of polymyxin in combination with other antibiotics. A total of 103 clinical A. baumannii strains were used to determine antibiotic susceptibility, biofilm formation capacity, and motility. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting was used to determine the genetic variation among strains. The distribution of 17 genes related to the resistance-nodulation-cell division (RND)-type efflux, autoinducer-receptor (AbaI/AbaR) quorum sensing, oxacillinases (OXA)-23, and insertion sequence of ISAba1 element was investigated. The representative strains were chosen to evaluate the gene transcription and the antibiofilm activity by polymyxin B (PB) in combination with merapenem, levofloxacin, and ceftazidime, respectively. ERIC-PCR-dependent fingerprints were found to be associated with carbapenem resistance and multidrug resistance. The presence of blaOXA-23 was found to correlate with genes involved in ISAba1 insertion, AbaI/AbaR quorum sensing, and AdeABC efflux. Carbapenem resistance was observed to be negatively correlated with biofilm formation and positively correlated with motility. PB in combination with ceftazidime displayed a synergistic antibiofilm effect against robust biofilm formed by an A. baumannii strain with deficiency in AbaI/AbaR quorum sensing. Our results not only clarify the genetic correlation among carbapenem resistance, biofilm formation, and pathogenicity in a certain level but also provide a theoretical basis for clinical applications of polymyxin-based combination of antibiotics in antibiofilm therapy. IMPORTANCE Deeper explorations of molecular correlation among antibiotic resistance, biofilm formation, and pathogenicity could provide novel insights that would facilitate the development of therapeutics and prevention against A. baumannii biofilm-related infections. The major finding that polymyxin B in combination with ceftazidime displayed a synergistic antibiofilm effect against robust biofilm formed by an A. baumannii strain with genetic deficiency in AbaI/AbaR quorum sensing further provides a theoretical basis for clinical applications of antibiotics in combination with quorum quenching in antibiofilm therapy.
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Virulence Characteristics of Biofilm-Forming Acinetobacter baumannii in Clinical Isolates Using a Galleria mellonella Model. Microorganisms 2021; 9:microorganisms9112365. [PMID: 34835490 PMCID: PMC8625498 DOI: 10.3390/microorganisms9112365] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 12/15/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative coccobacillus responsible for severe hospital-acquired infections, particularly in intensive care units (ICUs). The current study was designed to characterize the virulence traits of biofilm-forming carbapenem-resistant A. baumannii causing pneumonia in ICU patients using a Galleria mellonella model. Two hundred and thirty patients with hospital-acquired or ventilator-associated pneumonia were included in our study. Among the total isolates, A. baumannii was the most frequently isolated etiological agent in ICU patients with pneumonia (54/165, 32.7%). All A. baumannii isolates were subjected to antimicrobial susceptibility testing by the Kirby–Bauer disk diffusion method, while the minimum inhibitory concentrations of imipenem and colistin were estimated using the broth microdilution technique. The biofilm formation activity of the isolates was tested using the microtiter plate technique. Biofilm quantification showed that 61.1% (33/54) of the isolates were strong biofilm producers, while 27.7% (15/54) and 11.1% (6/54) showed moderate or weak biofilm production. By studying the prevalence of carbapenemases-encoding genes among isolates, blaOXA-23-like was positive in 88.9% of the isolates (48/54). The BlaNDM gene was found in 27.7% of the isolates (15/54 isolates). BlaOXA-23-like and blaNDM genes coexisted in 25.9% (14/54 isolates). Bap and blaPER-1 genes, the biofilm-associated genes, coexisted in 5.6% (3/54) of the isolates. For in vivo assessment of A. baumannii pathogenicity, a Galleria mellonella survival assay was used. G. mellonella survival was statistically different between moderate and poor biofilm producers (p < 0.0001). The killing effect of the strong biofilm-producing group was significantly higher than that of the moderate and poor biofilm producers (p < 0.0001 for each comparison). These findings highlight the role of biofilm formation as a powerful virulence factor for carbapenem-resistant A. baumannii that causes pneumonia in the ICU.
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Bian X, Liu X, Zhang X, Li X, Zhang J, Zheng H, Song S, Li X, Feng M. Epidemiological and genomic characteristics of Acinetobacter baumannii from different infection sites using comparative genomics. BMC Genomics 2021; 22:530. [PMID: 34247587 PMCID: PMC8272988 DOI: 10.1186/s12864-021-07842-5] [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: 10/02/2020] [Accepted: 06/24/2021] [Indexed: 01/31/2023] Open
Abstract
Background Acinetobacter baumannii is a common nosocomial pathogen that poses a huge threat to global health. Owing to the severity of A. baumannii infections, it became necessary to investigate the epidemiological characteristics of A. baumannii in Chinese hospitals and find the reasons for the high antibiotic resistance rate and mortality. This study aimed to investigate the epidemiologic and genetic characteristics of A. baumannii isolated from patients with hospital acquired pneumonia (HAP), bloodstream infection (BSI) and urinary tract infection (UTI) in China and uncover potential mechanisms for multi-drug resistance and virulence characteristics of A. baumannii isolates. Results All isolates were classified into two primary clades in core gene-based phylogenetic relationship. Clonal complex 208 (CC208) mainly consisted of ST195 (32 %) and ST208 (24.6 %). CC208 and non-CC208 isolates had carbapenem resistance rates of 96.2 and 9.1 %, respectively. Core genes were enriched in ‘Amino acid transport and metabolism’, ‘Translation’, ‘Energy production and conversion’, ‘Transcription’, ‘Inorganic ion transport and metabolism’ and ‘Cell wall/membrane/envelope synthesis’. Most isolates possessed virulence factors related to polysaccharide biosynthesis, capsular polysaccharide synthesis and motility. Eleven isolates belong to ST369 or ST191 (oxford scheme) all had the virulence factor cap8E and it had a higher positive rate in UTI (35.3 %) than in BSI (18.9 %) and HAP (12.9 %). ABGRI1 antibiotic resistance islands were responsible for streptomycin, tetracycline and sulfonate resistance. The blaOXA−23 gene was the most probable cause for carbapenem resistance, although the blaOXA−66 gene with nonsynonymous SNPs (F82L, I129L) was not. Conclusions A. baumannii is a genomically variable pathogen that has the potential to cause a range of infectious diseases. There is high proportion of carbapenem resistance in isolates from all three infection sites (HAP, BSI and UTI), which can be attributed to the blaOXA−23 gene. CC208 is the predominant clone in blaOXA−23-carrying A. baumannii that should be monitored. Virulence factors involving bacteria motility and polysaccharide biosynthesis which are widespread in clinical A. baumannii strains deserve our attention. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07842-5.
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Affiliation(s)
- Xingchen Bian
- School of Pharmacy & Minhang Hospital, Fudan University, 826 Zhang Heng Rd, 201203, Shanghai, China.,Institute of Antibiotics, Huashan Hospital, Fudan University, 200040, Shanghai, China.,Key Laboratory of Clinical Pharmacology of Antibiotics, 200040, Shanghai, China.,Huashan Hospital, National Health Commission & National Clinical Research Center for Aging and Medicine, Fudan University, 200040, Shanghai, China
| | - Xiaofen Liu
- Institute of Antibiotics, Huashan Hospital, Fudan University, 200040, Shanghai, China.,Key Laboratory of Clinical Pharmacology of Antibiotics, 200040, Shanghai, China.,Huashan Hospital, National Health Commission & National Clinical Research Center for Aging and Medicine, Fudan University, 200040, Shanghai, China
| | - Xuefei Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, 200040, Shanghai, China
| | - Xin Li
- Institute of Antibiotics, Huashan Hospital, Fudan University, 200040, Shanghai, China.,Key Laboratory of Clinical Pharmacology of Antibiotics, 200040, Shanghai, China.,Huashan Hospital, National Health Commission & National Clinical Research Center for Aging and Medicine, Fudan University, 200040, Shanghai, China
| | - Jing Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, 200040, Shanghai, China.,Key Laboratory of Clinical Pharmacology of Antibiotics, 200040, Shanghai, China.,Huashan Hospital, National Health Commission & National Clinical Research Center for Aging and Medicine, Fudan University, 200040, Shanghai, China.,Phase I Unit, Huashan Hospital, Fudan University, 200040, Shanghai, China
| | - Huajun Zheng
- Chinese National Human Genome Center, 201203, Shanghai, China
| | - Sichao Song
- Chinese National Human Genome Center, 201203, Shanghai, China
| | - Xiang Li
- School of Pharmacy & Minhang Hospital, Fudan University, 826 Zhang Heng Rd, 201203, Shanghai, China.
| | - Meiqing Feng
- School of Pharmacy & Minhang Hospital, Fudan University, 826 Zhang Heng Rd, 201203, Shanghai, China.
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Ilsan NA, Lee YJ, Kuo SC, Lee IH, Huang TW. Antimicrobial Resistance Mechanisms and Virulence of Colistin- and Carbapenem-Resistant Acinetobacter baumannii Isolated from a Teaching Hospital in Taiwan. Microorganisms 2021; 9:microorganisms9061295. [PMID: 34198665 PMCID: PMC8232278 DOI: 10.3390/microorganisms9061295] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 01/01/2023] Open
Abstract
Acinetobacter baumannii, a Gram-negative bacterium, is an important nosocomial pathogen. Colistin-resistant A. baumannii is becoming a new concern, since colistin is one of the last-line antibiotics for infections by carbapenem-resistant A. baumannii. From 452 carbapenem-resistant isolates collected in a teaching hospital in Taipei, Taiwan, we identified seven that were resistant to colistin. Carbapenem resistance in these isolates is attributed to the presence of carbapenemase gene blaOXA-23 in their genomes. Colistin resistance is presumably conferred by mutations in the sensor kinase domain of PmrB found in these isolates, which are known to result in modification of colistin target lipid A via the PmrB-PmrA-PmrC signal transduction pathway. Overexpression of pmrC, eptA, and naxD was observed in all seven isolates. Colistin resistance mediated by pmrB mutations has never been reported in Taiwan. One of the seven isolates contained three mutations in lpxD and exhibited an altered lipopolysaccharide profile, which may contribute to its colistin resistance. No significant difference in growth rates was observed between the isolates and the reference strain, suggesting no fitness cost of colistin resistance. Biofilm formation abilities of the isolates were lower than that of the reference. Interestingly, one of the isolates was heteroresistant to colistin. Four of the isolates were significantly more virulent to wax moth larvae than the reference.
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Affiliation(s)
- Noor Andryan Ilsan
- International Master/Ph.D. Program in Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
| | - Yuarn-Jang Lee
- Department of Internal Medicine, Division of Infectious Diseases, Taipei Medical University Hospital, Taipei 11031, Taiwan;
- Department of Internal Medicine, Division of Infectious Diseases, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Shu-Chen Kuo
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan 35053, Taiwan;
| | - I-Hui Lee
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Tzu-Wen Huang
- Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Correspondence: ; Tel./Fax: +886-2-2736-1661 (ext. 3925); (ext. 3921)
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