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Imakiire A, Soutome S, Nakamura Y, Nakamatsu M, Miura K, Sakamoto Y, Umeda M. A novel method for determining viable bacteria from a mixture of dead and viable bacteria: Delayed real-time PCR (DR-PCR) method. J Microbiol Methods 2023; 214:106844. [PMID: 37858897 DOI: 10.1016/j.mimet.2023.106844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/16/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023]
Abstract
Aspiration pneumonia can occur in perioperative and older patients, and various oral care methods have been used to prevent it. To validate the effective oral care methods, measuring bacterial counts before and after oral care is necessary. However, isolating and quantifying viable bacteria from those that are inactivated by agents used in oral care is not possible. In this study, we developed a novel method, Delayed real-time PCR (DR-PCR), that can quantify only viable bacteria from mixed samples of viable and dead bacteria. This method takes advantage of the fact that dead bacteria do not grow but viable bacteria do. When the samples were incubated in a liquid medium for 4 hours, the higher the percentage of viable bacteria, the higher the rate of increase in the number of bacteria. This method showed that povidone‑iodine mouthwashing reduced the number of viable bacteria to approximately 1/4 of that before mouthwashing. Although DR-PCR is slightly more time consuming than real-time PCR, it is effective for studying changes in bacterial counts before and after oral care.
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Affiliation(s)
- Akira Imakiire
- Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Sakiko Soutome
- Department of Oral Health, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
| | - Yuichi Nakamura
- Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Moeko Nakamatsu
- Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Keiichiro Miura
- Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yuki Sakamoto
- Department of Dentistry and Oral Surgery, Kansai Medical University Medical Center, Osaka, Japan
| | - Masahiro Umeda
- Department of Clinical Oral Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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Liu W, Xiang P, Ji Y, Chen Z, Lei Z, Huang W, Huang W, Liu D. Response of viable bacteria to antibiotics in aerobic granular sludge: Resistance mechanisms and behaviors, bacterial communities, and driving factors. Water Research 2023; 245:120656. [PMID: 37748345 DOI: 10.1016/j.watres.2023.120656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/31/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023]
Abstract
The assessment of antimicrobial resistance (AMR) risk by DNA-based techniques mainly relies on total bacterial DNA. In this case, AMR risk recognition is restricted to the genotype level, lacking crucial phenotypic information, such as the distribution of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in dead and viable bacteria. This limitation hinders the recognition of AMR behavior. Herein, based on propidium monoazide (PMA) shielding method, this work firstly quantified the intracellular ARGs/MGEs in viable and dead bacteria, and the impact of viable bacteria composition on the formation of intracellular/extracellular polymeric substance-related /cell-free ARGs (i/e/cARGs) and MGEs (i/e/cMGEs) in aerobic granular sludge (AGS). The shielding efficiency of PMA against dead bacteria was optimized to be as high as 97.5% when the MLSS of AGS was 2.0 g/L. Under antibiotic stimulation, 29.0% ∼ 49.0% of iARGs/iMGEs were carried by viable bacteria, and the remaining proportion were carried by dead bacteria. 18 out of the top 20 dominant genera showed a change in abundance by more than 1% after PMA treatment. 29 viable hosts were identified to associate with 52 iARGs, of which 28 and 15 hosts were also linked to 40 eARGs and 26 cARGs. Also, partial least-squares path model and variance partitioning analysis disclosed that viable bacteria and i/e/cMGEs had a positive effect on i/e/cARGs, with both contributing as much as 64.5% to the total ARGs enrichment. These results better visualized the AMR risk carried by viable bacteria and the categories of viable hosts. This work provides a novel insight into analyzing the actual AMR risk and viable hosts, helping to the reduction and control of AMR in wastewater treatment plants.
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Affiliation(s)
- Wenhao Liu
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Peng Xiang
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yuan Ji
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zeyou Chen
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhongfang Lei
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Weiwei Huang
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Hainan University, Renmin Road, Haikou 570228, China
| | - Wenli Huang
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Dongfang Liu
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
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Yuan S, Qi M, Peng Q, Huang G, Liu J, Xu Z, Gong X, Zhang G. Adaptive behaviors of planktonic Pseudomonas aeruginosa in response to the surface-deposited dead siblings. Colloids Surf B Biointerfaces 2020; 197:111408. [PMID: 33099147 DOI: 10.1016/j.colsurfb.2020.111408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/23/2020] [Accepted: 10/08/2020] [Indexed: 11/27/2022]
Abstract
In this study, the 3D motion behaviors and the underlying adaptation mechanism of planktonic Pseudomonas aeruginosa (PAO1) in response to the deposited dead siblings nearby were explored. Utilizing a real-time 3D tracking technique, digital holographic microscopy (DHM), we demonstrate that planktonic cells near the surface covered with dead siblings have a lower density and a reduced 3D velocity compared with those upon viable ones. As a sign of chemosensory responses, bacteria swimming near the dead siblings exhibit increase in frequency of the 'flick' motion. Transcriptomic analysis by RNA-seq reveals an upregulated expression of dgcM and dgcE inhibited the movement of PAO1, accompanied by increased transcriptional levels of the virulence factor-related genes hcp1, clpV1, and vgrG1. Moreover, the decrease in l-glutamate and the increase in succinic acid in the metabolites of the dead bacteria layer promote the dispersion of planktonic bacteria. As a result, the dead siblings on a surface inhibit the bacterial accumulation and activate the adaptive defensive responses of planktonic PAO1 in the vicinity.
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Affiliation(s)
- Shuo Yuan
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Meng Qi
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Qingmei Peng
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Gui Huang
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Jun Liu
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Zhenbo Xu
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Xiangjun Gong
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates (South China University of Technology), PR China.
| | - Guangzhao Zhang
- Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, PR China
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