Journal of Microbiology

Journal Articles

Antimicrobial Efficacy of Allium cepa and Zingiber officinale Against the Milk‑Borne Pathogen Listeria monocytogenes: Abirami Arasu , Nagaram Prabha , Durga Devi , Praveen Kumar Issac , Khaloud Mohammed Alarjani , Dunia A. Al Farraj , Reem A. Aljeidi , Dina S. Hussein , Magesh Mohan , Jehad Zuhair Tayyeb , Ajay Guru , Jesu Arockiaraj; J. Microbiol. 2023;61(11):993-1011. Published online December 4, 2023; DOI: https://doi.org/10.1007/s12275-023-00086-w

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Abstract: Listeria monocytogenes is an important food-borne pathogen that causes listeriosis and has a high case fatality rate despite its low incidence. Medicinal plants and their secondary metabolites have been identified as potential antibacterial substances, serving as replacements for synthetic chemical compounds. The present studies emphasize two significant medicinal plants, Allium cepa and Zingiber officinale, and their efficacy against L. monocytogenes. Firstly, a bacterial isolate was obtained from milk and identified through morphology and biochemical reactions. The species of the isolate were further confirmed through 16S rRNA analysis. Furthermore, polar solvents such as methanol and ethanol were used for the extraction of secondary metabolites from A. cepa and Z. officinale. Crude phytochemical components were identified using phytochemical tests, FTIR, and GC–MS. Moreover, the antibacterial activity of the crude extract and its various concentrations were tested against L. monocytogenes. Among all, A. cepa in methanolic extracts showed significant inhibitory activity. Since, the A. cepa for methanolic crude extract was used to perform autography to assess its bactericidal activity. Subsequently, molecular docking was performed to determine the specific compound inhibition. The docking results revealed that four compounds displayed strong binding affinity with the virulence factor Listeriolysin-O of L. monocytogenes. Based on the above results, it can be concluded that the medicinal plant A. cepa has potential antibacterial effects against L. monocytogenes, particularly targeting its virulence.

Tubulysins are Essential for the Preying of Ciliates by Myxobacteria: Uisang Yu , Jiha Kim , Seohui Park , Kyungyun Cho; J. Microbiol. 2023;61(6):627-632. Published online June 14, 2023; DOI: https://doi.org/10.1007/s12275-023-00056-2

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4 Citations

Abstract: Tubulysins are bioactive secondary metabolites produced by myxobacteria that promote microtubule disassembly. Microtubules are required for protozoa such as Tetrahymena to form cilia and flagella. To study the role of tubulysins in myxobacteria, we co-cultured myxobacteria and Tetrahymena. When 4000 Tetrahymena thermophila and 5.0 × 108 myxobacteria were added to 1 ml of CYSE medium and co-cultured for 48 h, the population of T. thermophila increased to more than 75,000. However, co-culturing tubulysin-producing myxobacteria, including Archangium gephyra KYC5002, with T. thermophila caused the population of T. thermophila to decrease from 4000 to less than 83 within 48 h. Almost no dead bodies of T. thermophila were observed in the culture medium. Co-culturing of T. thermophila and the A. gephyra KYC5002 strain with inactivation of the tubulysin biosynthesis gene led to the population of T. thermophila increasing to 46,667. These results show that in nature, most myxobacteria are preyed upon by T. thermophila, but some myxobacteria prey on and kill T. thermophila using tubulysins. Adding purified tubulysin A to T. thermophila changed the cell shape from ovoid to spherical and caused cell surface cilia to disappear.

Biofilm characterization of Fusarium solani keratitis isolate: increased resistance to antifungals and UV light: Itzel Margarita Córdova-Alcántara , Diana Laura Venegas-Cortés , María Ángeles Martínez-Rivera , Néstor Octavio Pérez , Aida Verónica Rodriguez-Tovar; J. Microbiol. 2019;57(6):485-497. Published online May 27, 2019; DOI: https://doi.org/10.1007/s12275-019-8637-2

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42 Citations

Abstract: Fusarium solani has drawn phytopathogenic, biotechnological, and medical interest. In humans, it is associated with localized infections, such as onychomycosis and keratomycosis, as well as invasive infections in immunocompromised patients. One pathogenicity factor of filamentous fungi is biofilm formation. There is still only scarce information about the in vitro mechanism of the formation and composition of F. solani biofilm. In this work, we describe the biofilm formed by a clinical keratomycosis isolate in terms of its development, composition and susceptibility to different antifungals and ultraviolet light (UV) at different biofilm formation stages. We found five biofilm formation stages using scanning electron microscopy: adherence, germination, hyphal development, maturation, and cell detachment. Using epifluorescence microscopy with specific fluorochromes, it was elucidated that the extracellular matrix consists of carbohydrates, proteins, and extracellular DNA. Specific inhibitors for these molecules showed significant biofilm reductions. The antifungal susceptibility against natamycin, voriconazole, caspofungin, and amphotericin B was evaluated by metabolic activity and crystal violet assay, with the F. solani biofilm preformation to 24 h increased in resistance to natamycin, voriconazole, and caspofungin, while the biofilm preformation to 48 h increased in resistance to amphotericin B. The preformed biofilm at 24 h protected and reduced UV light mortality. F. solani isolate could produce a highly structured extra biofilm; its cellular matrix consists of carbohydrate polymers, proteins, and eDNA. Biofilm confers antifungal resistance and decreases its susceptibility to UV light. The fungal biofilm functions as a survival strategy against antifungals and environmental factors.

Increased susceptibility against Cryptococcus neoformans of lupus mouse models (pristane-induction and FcGRIIb deficiency) is associated with activated macrophage, regardless of genetic background: Saowapha Surawut , Jiradej Makjaroen , Arthid Thim-uam , Jutamas Wongphoom , Tanapat Palaga , Prapaporn Pisitkun , Ariya Chindamporn , Asada Leelahavanichkul; J. Microbiol. 2019;57(1):45-53. Published online November 19, 2018; DOI: https://doi.org/10.1007/s12275-019-8311-8

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13 Citations

Abstract: The severity of cryptococcosis in lupus from varying geneticbackgrounds might be different due to the heterogeneity of lupus-pathogenesis. This study explored cryptococcosis in lupus mouse models of pristane-induction (normal geneticbackground) and FcGRIIb deficiency (genetic defect). Because the severity of lupus nephritis, as determined by proteinuria and serum creatinine, between pristane and FcGRIIb-/- mice were similar at 6-month-old, Cryptococcus neoformans was intravenously administered in 6-month-old mice and were age-matched with wild-type. Indeed, the cryptococcosis disease severity, as evaluated by mortality rate, internal-organ fungal burdens and serum cytokines, between pristane and FcGRIIb-/- mice was not different. However, the severity of cryptococcosis in wild-type was less severe than the lupus mice. On the other hand, phagocytosis activity of peritoneal macrophages from lupus mice (pristane and FcGRIIb-/-) was more predominant than the wild-type without the difference in macrophage killing-activity among these groups. In addition, the number of active T helper cells (Th-cell) in the spleen, including Th-cells with intracellular IFN-γ, from lupus mice (pristane and FcGRIIb-/-) was higher than wildtype. Moreover, these active Th-cells were even higher after 2 weeks of cryptococcal infection. These data support enhanced macrophage activation through prominent Th-cells in both lupus models. In conclusion, an increased susceptibility of cryptococcosis in both lupus models was independent to genetic background. This might due to Th-cell enhanced macrophage phagocytosis with the interference of macrophage killing activity from Cryptococcal immune-evasion properties.

Research Support, Non-U.S. Gov't

Pregnancy - associated human listeriosis: Virulence and genotypic analysis of Listeria monocytogenes from clinical samples: Dharmendra Kumar Soni , Durg Vijai Singh , Suresh Kumar Dubey; J. Microbiol. 2015;53(9):653-660. Published online August 1, 2015; DOI: https://doi.org/10.1007/s12275-015-5243-9

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30 Citations

Abstract: Listeria monocytogenes, a life-threatening pathogen, poses severe risk during pregnancy, may cause abortion, fetal death or neonatal morbidity in terms of septicemia and meningitis. The present study aimed at characterizing L. monocytogenes isolated from pregnant women based on serotyping, antibiotic susceptibility, virulence genes, in vivo pathogenicity test and ERIC- and REP-PCR fingerprint analyses. The results revealed that out of 3700 human clinical samples, a total of 30 (0.81%) isolates [12 (0.80%) from placental bit (1500), 18 (0.81%) from vaginal swab (2200)] were positive for L. monocytogenes. All the isolates belonged to serogroup 4b, and were + ve for virulence genes tested i.e. inlA, inlC, inlJ, plcA, prfA, actA, hlyA, and iap. Based on the mice inoculation tests, 20 isolates showed 100% and 4 isolates 60% relative virulence while 6 isolates were non-pathogenic. Moreover, 2 and 10 isolates were resistant to ciprofloxacin and cefoxitin, respectively, while the rest susceptible to other antibiotics used in this study. ERIC- and REP-PCR collectively depicted that the isolates from placental bit and vaginal swab had distinct PCR fingerprints except a few isolates with identical patterns. This study demonstrates prevalence of pathogenic strains mostly resistant to cefoxitin and/or ciprofloxacin. The results indicate the importance of isolating and characterizing the pathogen from human clinical samples as the pre-requisite for accurate epidemiological investigations.

Review

Minireview] The molecular mechanism of azole resistance in Aspergillus fumigatus: from bedside to bench and back: Xiaolei Wei , Yuanwei Zhang Zhang , Ling Lu; J. Microbiol. 2015;53(2):91-99. Published online January 28, 2015; DOI: https://doi.org/10.1007/s12275-015-5014-7

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26 Citations

Abstract: The growing use of immunosuppressive therapies has resulted in a dramatic increased incidence of invasive fungal infections (IFIs) caused by Aspergillus fumigatus, a common pathogen, and is also associated with a high mortality rate. Azoles are the primary guideline-recommended therapy agents for first-line treatment and prevention of IFIs. However, increased azole usage in medicinal and agricultural settings has caused azole-resistant isolates to repeatedly emerge in the environment, resulting in a significant threat to human health. In this review, we present and summarize current research on the resistance mechanisms of azoles in A. fumigatus as well as efficient susceptibility testing methods. Moreover, we analyze and discuss the putative clinical (bedside) indication of these findings from bench work.

Research Support, Non-U.S. Gov'ts

Candida albicans ENO1 Null Mutants Exhibit Altered Drug Susceptibility, Hyphal Formation, and Virulence: Hui-Ching Ko , Ting-Yin Hsiao , Chiung-Tong Chen , Yun-Liang Yang; J. Microbiol. 2013;51(3):345-351. Published online June 28, 2013; DOI: https://doi.org/10.1007/s12275-013-2577-z

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40 Citations

Abstract: We previously showed that the expression of ENO1 (enolase) in the fungal pathogen Candida albicans is critical for cell growth. In this study, we investigate the contribution of the ENO1 gene to virulence. We conducted our functional study of ENO1 in C. albicans by constructing an eno1/eno1 null mutant strain in which both ENO1 alleles in the genome were knockouted with the SAT1 flipper cassette that contains the nourseothricin-resistance marker. Although the null mutant failed to grow on synthetic media containing glucose, it was capable of growth on media containing yeast extract, peptone, and non-fermentable carbon sources. The null mutant was more susceptible to certain antifungal drugs. It also exhibited defective hyphal formation, and was avirulent in BALB/c mice.

A New Quorum-Sensing Inhibitor Attenuates Virulence and Decreases Antibiotic Resistance in Pseudomonas aeruginosa: Yu-Xiang Yang , Zhen-Hua Xu , Yu-Qian Zhang , Jing Tian , Li-Xing Weng , Lian-Hui Wang; J. Microbiol. 2012;50(6):987-993. Published online December 30, 2012; DOI: https://doi.org/10.1007/s12275-012-2149-7

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66 Citations

Abstract: Quorum sensing (QS) has been a novel target for the treatment of infectious diseases. Here structural analogs of Pseudomonas aeruginosa autoinducer N-acyl homoserine lactone (AHL) were investigated for QS inhibitor (QSI) activity and a novel QSI was discovered, N-decanoyl-L-homoserine benzyl ester (C2). Virulence assays showed that C2 downregulated total protease and elastase activities, as well as the production of rhamnolipid, that are controlled by QS in P. aeruginosa wild-type strain PAO1 without affecting growth. C2 was also shown to inhibit swarming motility of PAO1. Using a microdilution checkerboard method, we identified synergistic interactions between C2 and several antibiotics, tobramycin, gentamycin, cefepime, and meropenem. Data from real-time RT-PCR suggested that C2 inhibited the expression of lasR (29.67%), lasI (21.57%), rhlR (28.20%), and rhlI (29.03%).

Journal Article

Epidemiological Features and Resistance Pattern in Uropathogens Isolated from Chronic Bacterial Prostatitis: Tommaso Cai , Sandra Mazzoli , Francesca Meacci , Vieri Boddi , Nicola Mondaini , Gianni Malossini , Riccardo Bartoletti; J. Microbiol. 2011;49(3):448-454. Published online June 30, 2011; DOI: https://doi.org/10.1007/s12275-011-0391-z

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44 Citations

Abstract: Chronic bacterial prostatitis (CBP) is, usually, caused by uropathogens, especially gram-negative bacilli, although infection is sometimes due to Gram-positive and atypical microorganisms. A recent increasing in prevalence of Gram-positive strains has been reported. The aim of this study was to explore the epidemiological features and resistance rates in uropathogens isolated from CBP outpatients in last 10 years. All consecutive outpatients with demonstrated CBP attending a single Sexually Transmitted Disease centre from January 1997 and December 2008, were enrolled and underwent microbiological cultures in first void early morning urine, midstream urine, expressed prostatic secretion, and post prostate massage urine. Prevalence of different bacterial strains was stratified in four different periods: 1997-1999, 2000-2002, 2003-2005, 2006-2008. Any changes observed in epidemiological features and resistance rates in uropathogens over the whole study period have been analyzed. The present study has been planned, thus, as in vitro study. From 6,221 patients, 4,601 Gram-positive and 1,620 Gram-negative bacterial strains have been isolated. Enterococcus faecalis and Escherichia coli strains are the first and second frequent pathogens found, respectively. Significant differences between E. faecalis prevalence in the 1997-1999 and 2006-2008 periods were found. E. coli showed a significant difference between prevalence in 1997-1999 and 2006-2008 periods. Gram-positive organisms showed a decreasing of susceptibility to ciprofloxacin as well as Gram-negative strains, while a good susceptibility to the levofloxacin was evidenced. E. faecalis prevalence seemed to be raised in 2006-2008 periods. Moreover, a decreasing of activity of ciprofloxacin and a good activity profile of levofloxacin have been reported.

Research Support, Non-U.S. Gov'ts

A Simple Colorimetric Method for Testing Antimicrobial Susceptibility of Biofilmed Bacteria: Shukho Kim , Mi Jin Kim , Hee Young Kang , Sung Yong Seol , Dong Taek Cho , Jungmin Kim; J. Microbiol. 2010;48(5):709-711. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0299-z

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21 Citations

Abstract: This study introduces a simple colorimetric method which can measure the antimicrobial susceptibility of bacteria in biofilms using trimethyl tetrazolium chloride (TTC) as an indicator of viable bacteria. The new method was utilized for the evaluation of antibiotic susceptibility of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus biofilms.

Diversity of Endophytic Enterobacteria Associated with Different Host Plants: Adalgisa Ribeiro Torres , Welington Luiz Araujo , Luciana Cursino , Mariangela Hungria , Fabio Plotegher , Fabio Luis Mostasso , Joao Lucio Azevedo; J. Microbiol. 2008;46(4):373-379. Published online August 31, 2008; DOI: https://doi.org/10.1007/s12275-007-0165-9

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38 Citations

Abstract: Fifty-three endophytic enterobacteria isolates from citrus, cocoa, eucalyptus, soybean, and sugar cane were evaluated for susceptibility to the antibiotics ampicillin and kanamycin, and cellulase production. Susceptibility was found on both tested antibiotics. However, in the case of ampicillin susceptibility changed according to the host plant, while all isolates were susceptible to kanamycin. Cellulase production also changed according to host plants. The diversity of these isolates was estimated by employing BOX-PCR genomic fingerprints and 16S rDNA sequencing. In total, twenty-three distinct operational taxonomic units (OTUs) were identified by employing a criterion of 60% fingerprint similarity as a surrogate for an OTU. The 23 OTUs belong to the Pantoea and Enterobacter genera, while their high diversity could be an indication of paraphyletic classification. Isolates representing nine different OTUs belong to Pantoea agglomerans, P. ananatis, P. stewartii, Enterobacter sp., and E. homaechei. The results of this study suggest that plant species may select endophytic bacterial genotypes. It has also become apparent that a review of the Pantoea/Enterobacter genera may be necessary.

Propagation of Bombyx mori Nucleopolyhedrovirus in Nonpermissive Insect Cell Lines: Soo-Dong Woo , Jong Yul Roh , Jae Young Choi , Byung Rae Jin; J. Microbiol. 2007;45(2):133-138.; DOI: https://doi.org/2522 [pii]

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Abstract: This study addresses the susceptibility of Spodoptera frugiperda (Sf9 and Sf21), Trichoplusia ni (Hi5), and S. exigua (Se301) cells to the Bombyx mori nucleopolyhedrovirus (BmNPV). Although these cells have classically been considered nonpermissive to BmNPV, the cytopathic effect, an increase in viral yield, and viral DNA synthesis by BmNPV were observed in Sf9, Sf21, and Hi5 cells, but not in Se301 cells. Very late gene expression by BmNPV in these cell lines was also detected via β-galactosidase expression under the control of the polyhedrin promoter. Sf9 cells were most susceptible to BmNPV in all respects, followed by Sf21 and Hi5 cells in decreasing order, while the Se301 cells evidenced no distinct viral replication. This particular difference in viral susceptibility in each of the cell lines can be utilized for our understanding of the mechanisms underlying the host specificity of NPVs.

Prevalence and Antibiotic Susceptibility of Vancomycin-Resistant Enterococci in Chicken Intestines and Fecal Samples from Healthy Young Children and Intensive Care Unit Patients: Shin Moo Kim , Eun Sook Shim , Chi Nam Seong; J. Microbiol. 2001;39(2):116-120.

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Abstract: The prevalence, resistance genotype and antibiotic susceptibility of vancomycin-resistant enterococci (VRE) were determined. Prevalence of VRE in chickens, healthy children and intensive care unit (ICU) patients was 43.0%, 12.7% and 24.1%, respectively. Forty out of 56 isolates from chicken intestines were identified as Enterococcus faecium, and 12 were E. faecalis. All the isolates contained the vanA gene. Nine out of 13 VRE isolates from patients and two out of 21 from healthy young children were identified as E. faecium. The resistance types of E. faecium, E. gallinarium and E. casseliflavus were VanA, VanC1, and VanC2, respectively. The mimimum inhibitory concentrations (MICs) of E. faecium, E. gallinarium, and E. casseliflavus to vancomycin were 512, 8 and 4 g/ml, respectively. Specifically, E. faecium isolates were resistant to most of antibiotics except ampicillin and gentamicin. This is the first report of high VanA type VRE prevalence in nonhospitalized young children in Korea.

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