Journal of Microbiology

Reviews

Membrane Proteins as a Regulator for Antibiotic Persistence in Gram‑Negative Bacteria: Jia Xin Yee , Juhyun Kim , Jinki Yeom; J. Microbiol. 2023;61(3):331-341. Published online February 17, 2023; DOI: https://doi.org/10.1007/s12275-023-00024-w

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Abstract: Antibiotic treatment failure threatens our ability to control bacterial infections that can cause chronic diseases. Persister bacteria are a subpopulation of physiological variants that becomes highly tolerant to antibiotics. Membrane proteins play crucial roles in all living organisms to regulate cellular physiology. Although a diverse membrane component involved in persistence can result in antibiotic treatment failure, the regulations of antibiotic persistence by membrane proteins has not been fully understood. In this review, we summarize the recent advances in our understanding with regards to membrane proteins in Gram-negative bacteria as a regulator for antibiotic persistence, highlighting various physiological mechanisms in bacteria.

REVIEW] Ribosome dependence of persister cell formation and resuscitation: Thomas K. Wood , Sooyeon Song , Ryota Yamasaki; J. Microbiol. 2019;57(3):213-219. Published online February 26, 2019; DOI: https://doi.org/10.1007/s12275-019-8629-2

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Abstract: Since most bacterial cells are starving, they must enter a resting stage. Persister is the term used for metabolically-dormant cells that are not spores, and these cells arise from stress such as that from antibiotics as well as that from starvation. Because of their lack of metabolism, persister cells survive exposure to multiple stresses without undergoing genetic change; i.e., they have no inherited phenotype and behave as wild-type cells once the stress is removed and nutrients are presented. In contrast, mutations allow resistant bacteria to grow in the presence of antibiotics and slow growth allows tolerant cells to withstand higher concentrations of antibiotics; hence, there are three closely-related phenotypes: persistent, resistant, and tolerant. In addition, since dormancy is so prevalent, persister cells must have a means for resuscitating (since so many cells should obtain this resting state). In this review, we focus on what is known about the formation and resuscitation of persister cells.

Journal Article

Identification and Methicillin Resistance of Coagulase-Negative Staphylococci Isolated from Nasal Cavity of Healthy Horses: Jolanta Karakulska , Karol Fijałkowski , Paweł Nawrotek , Anna Pobucewicz , Filip Poszumski , Danuta Czernomysy-Furowicz; J. Microbiol. 2012;50(3):444-451. Published online June 30, 2012; DOI: https://doi.org/10.1007/s12275-012-1550-6

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Abstract: The aim of this study was an analysis of the staphylococcal flora of the nasal cavity of 42 healthy horses from 4 farms, along with species identification of CoNS isolates and determination of resistance to 18 antimicrobial agents, particularly phenotypic and genotypic methicillin resistance. From the 81 swabs, 87 staphylococci were isolated. All isolates possessed the gap gene but the coa gene was not detected in any of these isolates. Using PCR-RFLP of the gap gene, 82.8% of CoNS were identified: S. equorum (14.9%), S. warneri (14.9%), S. sciuri (12.6%), S. vitulinus (12.6%), S. xylosus (11.5% ), S. felis (5.7%), S. haemolyticus (3.4%), S. simulans(3.4%), S. capitis (1.1%), S. chromogenes (1.1%), and S. cohnii subsp. urealyticus (1.1%). To our knowledge, this was the first isolation of S. felis from a horse. The species identity of the remaining Staphylococcus spp. isolates (17.2%) could not be determined from the gap gene PCR-RFLP analysis and 16S rRNA gene sequencing data. Based on 16S-23S intergenic transcribed spacer PCR, 11 different ITS-PCR profiles were identified for the 87 analyzed isolates. Results of API Staph were consistent with molecular identification of 17 (19.5%) isolates. Resistance was detected to only 1 or 2 of the 18 antimicrobial agents tested in the 17.2% CoNS isolates, including 6.9% MRCoNS. The mecA gene was detected in each of the 5 (5.7%) phenotypically cefoxitin-resistant isolates and in 12 (13.8%) isolates susceptible to cefoxitin. In total, from 12 horses (28.6%), 17 (19.5%) MRCoNS were isolated. The highest percentage of MRCoNS was noted among S. sciuri isolates (100%).

Iron Increases Susceptibilities of Pseudomonas aeruginosa to Ofloxacin by Increasing the Permeability: Sookyoung Kim , Jinsook Kim , Hyeran Nam , Yusun Jung , Yeonhee Lee; J. Microbiol. 2000;38(4):265-269.

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Abstract: Iron increased the susceptibilities of clinical isolates of Pseudomonas aeruginosa to quinolones. In the presence of iron, increased susceptibilities to ofloxacin were observed in twenty-six out of thirty isolates and with no change in four isolates. In the case of norfloxacin, iron increased susceptibilities of twelve isolates but did not render any change in eighteen isolates. In the case of ciprofloxacin, iron decreased the MICs (Minimal Inhibitory Concentration) of twenty isolates, increased the MIC of one isolate, and did not change the MICs of nine isolates. To find out how iron increased susceptibility to ofloxacin, bacterial cells were grown in Muller Hinton (MH) media and succinate minimal media (SMM) to induce iron acquisition systems and the intracellular ofloxacin concentrations were assayed in the presence of iron. The addition of iron to the media decreased the MICs of cells whether they were grown in MH or SMM. Siderophores, carbonyl cyanide m-chlorophenylhydrazone (an inhibitor of proton motive force), and ouabain (an inhibitor of ATPase) did not decrease the effect of iron. Results suggested that the increase in the intracellular ofloxacin concentration by iron is accomplished not by decreasing the efflux but by increasing the ofloxacin permeability.

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