scholarly journals Ciprofloxacin-induced persister-cells in Campylobacter jejuni

Microbiology ◽  
2020 ◽  
Vol 166 (9) ◽  
pp. 849-853 ◽  
Author(s):  
Armen Ovsepian ◽  
Marianne Halberg Larsen ◽  
Christina Skovgaard Vegge ◽  
Hanne Ingmer
Keyword(s):  
Campylobacter Jejuni ◽  
Type Species ◽  
Bacterial Infections ◽  
Bacterial Species ◽  
Cell Formation ◽  
Fluoroquinolone Resistance ◽  
Persister Cells ◽  
Content Type ◽  
Link Type ◽  
Persister Cell

Campylobacter jejuni is a major bacterial foodborne-pathogen. Ciprofloxacin is an important antibiotic for the treatment of C. jejuni , albeit high rates of fluoroquinolone resistance have limited its usefulness. Persister-cells are transiently antibiotic-tolerant fractions of bacterial populations and their occurrence has been associated with recalcitrant and persistent bacterial infections. Here, time-kill assays with ciprofloxacin (200×MIC, 25 µg ml−1) were performed in C. jejuni strains 81–176 and RM1221 and persister-cells were found. The frequency of survivors after 8 h of ciprofloxacin exposure was approx. 10−3 for both strains, while after 22 h the frequency was between 10−5–10−7, depending on the strain and growth-phase. Interestingly, the stationary-phase cultures did not display more persister-cells compared to exponential-phase cultures, in contrast to what has been observed in other bacterial species. Persister-cells after ampicillin exposure (100×MIC, 200 µg ml−1) were not detected, implying that persister-cell formation in C. jejuni is antibiotic-specific. In attempts to identify the mechanism of ciprofloxacin persister-cell formation, stringent or SOS responses were not found to play major roles. Overall, this study reports ciprofloxacin persister-cells in C. jejuni and challenges the notion of persister-cells as plainly dormant non-growing cells.

scholarly journals ClpP is required for proteolytic regulation of type II toxin–antitoxin systems and persister cell formation in Streptococcus mutans

2019 ◽  
Vol 1 (8) ◽  
Author(s):  
Xiao-Lin Tian ◽  
Miao Li ◽  
Zachariah Scinocca ◽  
Heather Rutherford ◽  
Yung-Hua Li
Keyword(s):  
Streptococcus Mutans ◽  
Type Species ◽  
Critical Role ◽  
Cell Formation ◽  
Type Ii ◽  
Wild Type ◽  
Content Type ◽  
Link Type ◽  
Viability Assay ◽  
Persister Cell

The type II toxin–antitoxin (TA) modules, mazEF and relBE, in Streptococcus mutans have been implicated in stress response, antibiotic tolerance and persister cell formation. However, how S. mutans regulates these systems to prevent unwanted toxin activation and persister cell formation is unclear. In this study, we provide evidence that ClpP is required for the proteolytic regulation of these TA systems and persister cell formation in S. mutans following antibiotic challenge. A persister viability assay showed that S. mutans UA159 (WT) formed a larger quantity of persister cells than its isogenic mutant ΔclpP following antibiotic challenge. However, the lux reporter assay revealed that clpP deletion did not affect the transcriptional levels of mazEF and relBE, since no significant differences (P>0.05) in the reporter activities were detected between the wild-type and ΔclpP background. Instead, all antibiotics tested at a sub-minimum inhibitory concentration (sub-MIC) induced transcriptional levels of mazEF and relBE operons. We then examined the protein profiles of His-tagged MazE and RelB proteins in the UA159 and ΔclpP backgrounds by Western blotting analysis. The results showed that S. mutans strains grown under non-stress conditions expressed very low but detectable levels of MazE and RelB antitoxin proteins. Antibiotics at sub-MICs induced the levels of the MazE and RelB proteins, but the protein levels decreased rapidly in the wild-type background. In contrast, a stable level of MazE and RelB proteins could be detected in the ΔclpP mutant background, suggesting that both proteins accumulated in the ΔclpP mutant. We conclude that ClpP is required for the proteolytic regulation of cellular levels of the MazE and RelB antitoxins in S. mutans , which may play a critical role in modulating the TA activities and persister cell formation of this organism following antibiotic challenge.

scholarly journals High persister cell formation by clinical Staphylococcus aureus strains belonging to clonal complex 30

Microbiology ◽  
2020 ◽  
Vol 166 (7) ◽  
pp. 654-658 ◽  
Author(s):  
Liping Liu ◽  
Ying Wang ◽  
Martin Saxtorph Bojer ◽  
Paal Skytt Andersen ◽  
Hanne Ingmer
Keyword(s):  
Staphylococcus Aureus ◽  
Membrane Potential ◽  
Type Species ◽  
Cell Formation ◽  
Susceptible Population ◽  
Content Type ◽  
Clinical Strains ◽  
Link Type ◽  
Persister Cell

Bacterial persisters form a subpopulation of cells that survive lethal concentrations of antibiotics without being genetically different from the susceptible population. They are generally considered to be phenotypic variants that spontaneously have entered a dormant state with low ATP levels or reduced membrane potential. In Staphylococcus aureus , a serious opportunistic human pathogen, persisters are believed to contribute to chronic infections that are a major global healthcare problem. While S. aureus persisters have mostly been studied in laboratory strains, we have here investigated the ability of clinical strains to form persisters. For 44 clinical strains belonging to the major clonal complexes CC5, CC8, CC30 or CC45, we examined persister cell formation in stationary phase when exposed to 100 times the MIC of ciprofloxacin, an antibiotic that targets DNA replication. We find that while all strains are able to form persisters, those belonging to CC30 displayed on average 100-fold higher persister cell frequencies when compared to strains of other CCs. Importantly, there was no correlation between persister formation and the cellular ATP content of the individual strains, but the group of CC30 strains displayed slightly lower membrane potential compared to the non-CC30 group. CC30 strains have previously been associated with chronic and reoccuring infections and we hypothesize that there could be a correlation between lineage-specific characteristics displayed via in vitro persister assays and the observed clinical spectrum of disease.

Adaptation of gltA and ssrA assays for diversity profiling by Illumina sequencing to identify Bartonella henselae, B. clarridgeiae and B. koehlerae

2021 ◽  
Vol 70 (7) ◽  
Author(s):  
Rosemonde Isabella Power ◽  
Nichola Elisa Davies Calvani ◽  
Yaarit Nachum-Biala ◽  
Harold Salant ◽  
Shimon Harrus ◽  
...  
Keyword(s):  
Illumina Sequencing ◽  
Type Species ◽  
Bacterial Infections ◽  
Sanger Sequencing ◽  
Bartonella Henselae ◽  
Diagnostic Methods ◽  
Mixed Infections ◽  
Accurate Identification ◽  
Content Type ◽  
Link Type

Introduction. Bartonellosis is an emerging zoonotic disease caused by bacteria of the genus Bartonella . Mixed Bartonella infections are a well-documented phenomenon in mammals and their ectoparasites. The accurate identification of Bartonella species in single and mixed infections is valuable, as different Bartonella species have varying impacts on infected hosts. Gap Statement. Current diagnostic methods are inadequate at identifying the Bartonella species present in mixed infections. Aim. The aim of this study was to adopt a Next Generation Sequencing (NGS) approach using Illumina sequencing technology to identify Bartonella species and demonstrate that this approach can resolve mixed Bartonella infections. Methodology. We used Illumina PCR amplicon NGS to target the ssrA and gltA genes of Bartonella in fleas collected from cats, dogs and a hedgehog in Israel. We included artificially mixed Bartonella samples to demonstrate the ability for NGS to resolve mixed infections and we compared NGS to traditional Sanger sequencing. Results. In total, we identified 74 Ctenocephalides felis, two Ctenocephalides canis, two Pulex irritans and three Archaeopsylla e. erinacei fleas. Real-time PCR of a subset of 48 fleas revealed that twelve were positive for Bartonella , all of which were cat fleas. Sanger sequencing of the ssrA and gltA genes confirmed the presence of Bartonella henselae , Bartonella clarridgeiae and Bartonella koehlerae . Illumina NGS of ssrA and gltA amplicons further confirmed the Bartonella species identity in all 12 flea samples and unambiguously resolved the artificially mixed Bartonella samples. Conclusion. The adaptation and multiplexing of existing PCR assays for diversity profiling via NGS is a feasible approach that is superior to traditional Sanger sequencing for Bartonella speciation and resolving mixed Bartonella infections. The adaptation of other PCR primers for Illumina NGS will be useful in future studies where mixed bacterial infections may be present.

Emergence of a plasmid-borne tigecycline resistance in Klebsiella pneumoniae in Vietnam

2021 ◽  
Author(s):  
Aki Hirabayashi ◽  
Van Thi Thu Ha ◽  
An Van Nguyen ◽  
Son Thai Nguyen ◽  
Keigo Shibayama ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Gene Cluster ◽  
Type Species ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Whole Genome Sequence ◽  
High Sequence Identity ◽  
Pump System ◽  
Content Type ◽  
Link Type

Tigecycline is a last-resort antimicrobial used to treat multidrug-resistant Gram-negative bacterial infections. One of the common antimicrobial resistance mechanisms is the efflux pump system composed of membrane protein complexes to excrete xenobiotic substrates. Recently, a novel gene cluster, tmexCD1-toprJ1, encoding the resistance–nodulation–cell division (RND) efflux pump was identified on plasmids in Klebsiella pneumoniae isolates in China. TMexCD1-TOprJ1 was found to be capable of excreting multiple antimicrobials, including tigecycline, which contributed to the strain's resistance. In this study, we identified K. pneumoniae isolates harbouring the tmexCD1-toprJ1 genes outside of China for the first time. Two tigecycline-resistant K. pneumoniae isolates belonging to ST273 by multilocus sequence typing were collected from different patients in a medical institution in Hanoi, Vietnam, in 2015. Whole-genome sequence analysis revealed that these isolates harboured a 288.0 kb tmexCD1-toprJ1–carrying plasmid with IncFIB and IncHI1B replicons. The tmexCD1-toprJ1 gene cluster was surrounded by several mobile gene elements, including IS26, and the plasmids had high sequence identity with that of K. pneumoniae isolated in China. Our finding suggests that the horizontal spread of tigecycline resistance mediated by tmexCD1-toprJ1–carrying plasmids has occurred in Vietnam and other countries, and raises concern about the further global dissemination.

Nocardioides donggukensis sp. nov. and Hyunsoonleella aquatilis sp. nov., isolated from Jeongbang Waterfall on Jeju Island

2021 ◽  
Vol 71 (12) ◽  
Author(s):  
Inhyup Kim ◽  
Geeta Chhetri ◽  
Jiyoun Kim ◽  
Minchung Kang ◽  
Yoonseop So ◽  
...  
Keyword(s):  
Type Strain ◽  
Type Species ◽  
Bacterial Species ◽  
Jeju Island ◽  
Nucleotide Identity ◽  
Rrna Gene ◽  
Average Nucleotide Identity ◽  
Phenotypic Data ◽  
Content Type ◽  
Link Type

Two bacterial strains, designated MJB4T and SJ7T, were isolated from water samples collected from Jeongbang Falls on Jeju Island, Republic of Korea. Phylogenetic analysis of 16S rRNA gene sequences indicated that the two strains belonged to the genera Nocardioides and Hyunsoonleella , owing to their high similarities to Nocardioides jensenii DSM 29641T (97.5 %) and Hyunsoonleella rubra FA042 T (96.3 %), respectively. These values are much lower than the gold standard for bacterial species (98.7 %). The average nucleotide identity values between strains MJB4T, SJ7T and the reference strains, Nocardioides jensenii DSM 29641T, Nocardioides daejeonensis MJ31T and Hyunsoonleella flava T58T were 77.2, 75.9 and 75.4 %, respectively. Strains MJB4T and SJ7T and the type strains of the species involved in system incidence have average nucleotide identity and average amino acid threshold values of 60.1–82.6 % for the species boundary (95–96 %), which confirms that strains MJB4T and SJ7T represent two new species of genus Nocardioides and Hyunsoonleella , respectively. Based on phylogenetic and phenotypic data, strains MJB4T and SJ7T are considered to represent novel species of the genus Nocardioides and Hyunsoonleella , respectively, for which the names Nocardioides donggukensis sp. nov. (type strain MJB4T=KACC 21724T=NBRC 114402T) and Hyunsoonleella aquatilis sp. nov., (type strain SJ7T=KACC 21715T=NBRC 114486T) have been proposed.

Pseudoalteromonas ostreae sp. nov., a new bacterial species harboured by the flat oyster Ostrea edulis

2021 ◽  
Vol 71 (11) ◽  
Author(s):  
Héléna Cuny ◽  
Clément Offret ◽  
Amine M. Boukerb ◽  
Leila Parizadeh ◽  
Olivier Lesouhaitier ◽  
...  
Keyword(s):  
Type Species ◽  
Bacterial Species ◽  
Acid Methyl Ester ◽  
Phenotypic Traits ◽  
Rrna Gene ◽  
Ostrea Edulis ◽  
Content Type ◽  
Link Type ◽  
A Genome ◽  
Flat Oyster

Three bacterial strains, named hOe-66T, hOe-124 and hOe-125, were isolated from the haemolymph of different specimens of the flat oyster Ostrea edulis collected in Concarneau bay (Finistère, France). These strains were characterized by a polyphasic approach, including (i) whole genome analyses with 16S rRNA gene sequence alignment and pangenome analysis, determination of the G+C content, average nucleotide identity (ANI), and in silico DNA–DNA hybridization (isDDH), and (ii) fatty acid methyl ester and other phenotypic analyses. Strains hOe-66T, hOe-124 and hOe-125 were closely related to both type strains Pseudoalteromonas rhizosphaerae RA15T and Pseudoalteromonas neustonica PAMC 28425T with less than 93.3% ANI and 52.3% isDDH values. Regarding their phenotypic traits, the three strains were Gram-negative, 1–2 µm rod-shaped, aerobic, motile and non-spore-forming bacteria. Cells grew optimally at 25 °C in 2.5% NaCl and at 7–8 pH. The most abundant fatty acids were summed feature 3 (C16:1 ω7c/C16:1 ω6c), C16:0 and C17:1 ω8c. The strains carried a genome average size of 4.64 Mb and a G+C content of 40.28 mol%. The genetic and phenotypic results suggested that strains hOe-66T, hOe-124 and hOe-125 belong to a new species of the genus Pseudoalteromonas . In this context, we propose the name Pseudoalteromonas ostreae sp. nov. The type strain is hOe-66T (=CECT 30303T=CIP 111911T).

scholarly journals Pseudomonas granadensis sp. nov., a new bacterial species isolated from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain

2015 ◽  
Vol 65 (Pt_2) ◽  
pp. 625-632 ◽  
Author(s):  
Javier Pascual ◽  
Marina García-López ◽  
Gerald F. Bills ◽  
Olga Genilloud
Keyword(s):  
Dna Hybridization ◽  
Type Species ◽  
Novel Species ◽  
Bacterial Species ◽  
Phenotypic Traits ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Link Type ◽  
Natural Park ◽  
Fatty Acid Compositions

During the course of screening bacterial isolates as sources of as-yet unknown bioactive compounds with pharmaceutical applications, a chemo-organotrophic, Gram-negative bacterium was isolated from a soil sample taken from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain. Strain F-278,770T was oxidase- and catalase-positive, aerobic, with a respiratory type of metabolism with oxygen as the terminal electron acceptor, non-spore-forming and motile by one polar flagellum, although some cells had two polar flagella. Phylogenetic analysis of the 16S rRNA, gyrB, rpoB and rpoD genes revealed that strain F-278,770T belongs to the Pseudomonas koreensis subgroup (Pseudomonas fluorescens lineage), with Pseudomonas moraviensis , P. koreensis , P. baetica and P. helmanticensis as its closest relatives. Chemotaxonomic traits such as polar lipid and fatty acid compositions and G+C content of genomic DNA corroborated the placement of strain F-278,770T in the genus Pseudomonas . DNA–DNA hybridization assays and phenotypic traits confirmed that this strain represents a novel species of the genus Pseudomonas , for which the name Pseudomonas granadensis sp. nov. is proposed. The type strain is F-278,770T ( = DSM 28040T = LMG 27940T).

scholarly journals Prevalence of Mycoplasma genitalium fluoroquinolone-resistance markers, and dual-class-resistance markers, in asymptomatic men who have sex with men

2021 ◽  
Vol 70 (9) ◽  
Author(s):  
Teck-Phui Chua ◽  
Kaveesha Bodiyabadu ◽  
Dorothy A. Machalek ◽  
Suzanne M. Garland ◽  
Catriona S. Bradshaw ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Type Species ◽  
Health Centre ◽  
Mycoplasma Genitalium ◽  
Fluoroquinolone Resistance ◽  
Content Type ◽  
Link Type ◽  
Resistance Markers ◽  
Sex With Men ◽  
Dual Class

Introduction. Failure of fluoroquinolones, the principal treatment option for macrolide-resistant Mycoplasma genitalium infections, has recently emerged. This is of particular concern for men who have sex with men (MSM), who have high proportions of macrolide-resistant M. genitalium infections. Treatment failure with moxifloxacin is likely the result of single nucleotide polymorphisms (SNPs) in parC, whilst concurrent gyrA mutations may play a role. Gap Statement. The levels of fluoroquinolone resistance and dual-class (i.e. macrolide and fluoroquinolone) resistance in M. genitalium among asymptomatic MSM is unknown. Aim. To (i) determine the proportion of fluoroquinolone resistance and dual-class resistance in M. genitalium infections among asymptomatic MSM, (ii) explore any clinical and behavioural associations with fluoroquinolone resistance, and (iii) determine the distribution of antibiotic resistance among M. genitalium mgpB sequence types (STs). Methodology. M. genitalium positive samples (N=94) were obtained from 1001 asymptomatic MSM enrolled in a study at Melbourne Sexual Health Centre (Carlton, Australia) between August 2016 and September 2017. Sanger sequencing was performed to determine the proportion of M. genitalium infections with SNPs in parC that have previously been associated with failure of moxifloxacin (corresponding to amino changes S83I, D83R, D87Y and D87N) and in gyrA (corresponding to amino acid changes M95I, D99N, D99Y and D99G). Associations between clinical/behavioural factors and parC SNPs were examined. Strain typing was performed by sequencing a portion of the mgpB gene. Results. The proportion of MSM with infections harbouring parC and gyrA SNPs was 13.0 % [95 % confidence interval (CI): 6.8–23.2 %] and 4.7 % (95 % CI: 1.1–13.4 %), respectively; dual-class resistance was 13.0 %. No significant clinical/behavioural associations were found. Antibiotic resistance was not restricted to specific mgpB STs. Conclusion. One in eight (13 %) of asymptomatic MSM with M. genitalium had an infection with dual-class-resistance mutations. Typing by mgpB sequence suggested fluoroquinolone resistance is arising from independent mutation events. This study illustrates that asymptomatic MSM may act as a reservoir for antibiotic-resistant M. genitalium .

scholarly journals Genome analysis-based reclassification of Pseudomonas fuscovaginae and Pseudomonas shirazica as later heterotypic synonyms of Pseudomonas asplenii and Pseudomonas asiatica, respectively

2020 ◽  
Vol 70 (5) ◽  
pp. 3547-3552 ◽  
Author(s):  
Mari Tohya ◽  
Shin Watanabe ◽  
Tatsuya Tada ◽  
Htay Htay Tin ◽  
Teruo Kirikae
Keyword(s):  
Dna Hybridization ◽  
Type Species ◽  
Bacterial Species ◽  
Taxonomic Status ◽  
Species Delineation ◽  
Genome Sequences ◽  
Content Type ◽  
Link Type ◽  
Type Strains ◽  
Group Species

This study was conducted to clarify the taxonomic status of the species Pseudomonas fuscovaginae and Pseudomonas shirazica . Whole genome sequences for the type strains of P. fuscovaginae and P. shirazica were compared against the closely related type strains of the Pseudomonas putida group and the Pseudomonas fluorescens group species. Average nucleotide identity and digital DNA–DNA hybridization values between P. fuscovaginae LMG 2158T and Pseudomonas asplenii ATCC 23835T were 98.4 and 85.5 %, and between P. shirazica VM14T and Pseudomonas asiatica RYU5T were 99.3 and 95.3 %. These values were greater than recognized thresholds for bacterial species delineation, indicating that they belong to the same genomospecies, respectively. Therefore, P. fuscovaginae and P. shirazica should be reclassified as later heterotypic synonyms of P. asplenii and P. asiatica , respectively.

scholarly journals Reclassification of the biocontrol agents Bacillus subtilis BY-2 and Tu-100 as Bacillus velezensis and insights into the genomic and specialized metabolite diversity of the species

Microbiology ◽  
2020 ◽  
Vol 166 (12) ◽  
pp. 1121-1128 ◽  
Author(s):  
Alex J. Mullins ◽  
Yinshui Li ◽  
Lu Qin ◽  
Xiaojia Hu ◽  
Lihua Xie ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Natural Product ◽  
Type Species ◽  
Bacterial Species ◽  
Gene Clusters ◽  
Core Gene ◽  
Biocontrol Agents ◽  
Bacillus Velezensis ◽  
Content Type ◽  
Link Type

The genomes of two historical Bacillus species strains isolated from the roots of oilseed rape and used routinely in PR China as biocontrol agents to suppress Sclerotinia disease were sequenced. Average nucleotide identity (ANI) and digital DNA–DNA hybridization analyses demonstrated that they were originally misclassified as Bacillus subtilis and now belong to the bacterial species Bacillus velezensis . A broader ANI analysis of available Bacillus genomes identified 292 B. velezensis genomes that were then subjected to core gene analysis and phylogenomics. Prediction and dereplication of specialized metabolite biosynthetic gene clusters (BGCs) defined the prevalence of multiple antimicrobial-associated BGCs and highlighted the natural product potential of B. velezensis . By defining the core and accessory antimicrobial biosynthetic capacity of the species, we offer an in-depth understanding of B. velezensis natural product capacity to facilitate the selection and testing of B. velezensis strains for use as biological control agents.

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