scholarly journals Heterogeneous Antimicrobial Susceptibility Characteristics inPseudomonas aeruginosaIsolates from Cystic Fibrosis Patients

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Xuan Qin ◽  
Chuan Zhou ◽  
Danielle M. Zerr ◽  
Amanda Adler ◽  
Amin Addetia ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Genomic Sequence ◽  
Sequence Data ◽  
Parental Origin ◽  
Adaptive Mutations ◽  
Wide Range ◽  
Susceptibility Patterns

ABSTRACTClinical isolates ofPseudomonas aeruginosafrom patients with cystic fibrosis (CF) are known to differ from those associated with non-CF hosts by colony morphology, drug susceptibility patterns, and genomic hypermutability.Pseudomonas aeruginosaisolates from CF patients have long been recognized for their overall reduced rate of antimicrobial susceptibility, but their intraclonal MIC heterogeneity has long been overlooked. Using two distinct cohorts of clinical strains (n= 224 from 56 CF patients,n= 130 from 68 non-CF patients) isolated in 2013, we demonstrated profound Etest MIC heterogeneity in CFP. aeruginosaisolates in comparison to non-CFP. aeruginosaisolates. On the basis of whole-genome sequencing of 19 CFP. aeruginosaisolates from 9 patients with heterogeneous MICs, the core genome phylogenetic tree confirmed the within-patient CFP. aeruginosaclonal lineage along with considerable coding sequence variability. No extrachromosomal DNA elements or previously characterized antibiotic resistance mutations could account for the wide divergence in antimicrobial MICs betweenP. aeruginosacoisolates, though many heterogeneous mutations in efflux and porin genes and their regulators were present. A unique OprD sequence was conserved among the majority of isolates of CFP. aeruginosaanalyzed, suggesting a pseudomonal response to selective pressure that is common to the isolates. Genomic sequence data also suggested that CF pseudomonal hypermutability was not entirely due to mutations inmutL,mutS, anduvr. We conclude that the net effect of hundreds of adaptive mutations, both shared between clonally related isolate pairs and unshared, accounts for their highly heterogeneous MIC variances. We hypothesize that this heterogeneity is indicative of the pseudomonal syntrophic-like lifestyle under conditions of being “locked” inside a host focal airway environment for prolonged periods.IMPORTANCEPatients with cystic fibrosis endure “chronic focal infections” with a variety of microorganisms. One microorganism,Pseudomonas aeruginosa, adapts to the host and develops resistance to a wide range of antimicrobials. Interestingly, as the infection progresses, multiple isogenic strains ofP. aeruginosaemerge and coexist within the airways of these patients. Despite a common parental origin, the multiple strains ofP. aeruginosadevelop vastly different susceptibility patterns to actively used antimicrobial agents—a phenomenon we define as “heterogeneous MICs.” By sequencing pairs ofP. aeruginosaisolates displaying heterogeneous MICs, we observed widespread isogenic gene lesions in drug transporters, DNA mismatch repair machinery, and many other structural or cellular functions. Coupled with the heterogeneous MICs, these genetic lesions demonstrated a symbiotic response to host selection and suggested evolution of a multicellular syntrophic bacterial lifestyle. Current laboratory standard interpretive criteria do not address the emergence of heterogeneous growth and susceptibilitiesin vitrowith treatment implications.

scholarly journals Pseudomonas aeruginosa PA14 Enhances the Efficacy of Norfloxacin against Staphylococcus aureus Newman Biofilms

2020 ◽  
Vol 202 (18) ◽  
Author(s):  
Giulia Orazi ◽  
Fabrice Jean-Pierre ◽  
George A. O’Toole
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Respiratory Infections ◽  
Multiple Infection ◽  
Bacterial Biofilms ◽  
Interspecies Interactions ◽  
Chronic Infections ◽  
Content Type

ABSTRACT The thick mucus within the airways of individuals with cystic fibrosis (CF) promotes frequent respiratory infections that are often polymicrobial. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent pathogens that cause CF pulmonary infections, and both are among the most common etiologic agents of chronic wound infections. Furthermore, the ability of P. aeruginosa and S. aureus to form biofilms promotes the establishment of chronic infections that are often difficult to eradicate using antimicrobial agents. In this study, we found that multiple LasR-regulated exoproducts of P. aeruginosa, including 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), siderophores, phenazines, and rhamnolipids, likely contribute to the ability of P. aeruginosa PA14 to shift S. aureus Newman norfloxacin susceptibility profiles. Here, we observe that exposure to P. aeruginosa exoproducts leads to an increase in intracellular norfloxacin accumulation by S. aureus. We previously showed that P. aeruginosa supernatant dissipates the S. aureus membrane potential, and furthermore, depletion of the S. aureus proton motive force recapitulates the effect of the P. aeruginosa PA14 supernatant on shifting norfloxacin sensitivity profiles of biofilm-grown S. aureus Newman. From these results, we hypothesize that exposure to P. aeruginosa PA14 exoproducts leads to increased uptake of the drug and/or an impaired ability of S. aureus Newman to efflux norfloxacin. Surprisingly, the effect observed here of P. aeruginosa PA14 exoproducts on S. aureus Newman susceptibility to norfloxacin seemed to be specific to these strains and this antibiotic. Our results illustrate that microbially derived products can alter the ability of antimicrobial agents to kill bacterial biofilms. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from multiple infection sites, including the lungs of individuals with cystic fibrosis (CF) and nonhealing diabetic foot ulcers. Coinfection with P. aeruginosa and S. aureus has been shown to produce worse outcomes compared to infection with either organism alone. Furthermore, the ability of these pathogens to form biofilms enables them to cause persistent infection and withstand antimicrobial therapy. In this study, we found that P. aeruginosa-secreted products dramatically increase the ability of the antibiotic norfloxacin to kill S. aureus biofilms. Understanding how interspecies interactions alter the antibiotic susceptibility of bacterial biofilms may inform treatment decisions and inspire the development of new therapeutic strategies.

scholarly journals Pseudomonas aeruginosa PA80 is a cystic fibrosis isolate deficient in RhlRI quorum sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Syed A. K. Shifat Ahmed ◽  
Michelle Rudden ◽  
Sabrina M. Elias ◽  
Thomas J. Smyth ◽  
Roger Marchant ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Genomic Islands ◽  
Clinical Strain ◽  
Whole Genome ◽  
Synonymous Mutations ◽  
Wide Range

AbstractPseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in P. aeruginosa is complex, intricate and is dominated by two main N-acyl-homoserine lactone circuits, LasRI and RhlRI. These two QS systems work in a hierarchical fashion with LasRI at the top, directly regulating RhlRI. Together these QS circuits regulate several virulence associated genes, metabolites, and enzymes in P. aeruginosa. Paradoxically, LasR mutants are frequently isolated from chronic P. aeruginosa infections, typically among cystic fibrosis (CF) patients. This suggests P. aeruginosa can undergo significant evolutionary pathoadaptation to persist in long term chronic infections. In contrast, mutations in the RhlRI system are less common. Here, we have isolated a clinical strain of P. aeruginosa from a CF patient that has deleted the transcriptional regulator RhlR entirely. Whole genome sequencing shows the rhlR locus is deleted in PA80 alongside a few non-synonymous mutations in virulence factors including protease lasA and rhamnolipid rhlA, rhlB, rhlC. Importantly we did not observe any mutations in the LasRI QS system. PA80 does not appear to have an accumulation of mutations typically associated with several hallmark pathoadaptive genes (i.e., mexT, mucA, algR, rpoN, exsS, ampR). Whole genome comparisons show that P. aeruginosa strain PA80 is closely related to the hypervirulent Liverpool epidemic strain (LES) LESB58. PA80 also contains several genomic islands (GI’s) encoding virulence and/or resistance determinants homologous to LESB58. To further understand the effect of these mutations in PA80 QS regulatory and virulence associated genes, we compared transcriptional expression of genes and phenotypic effects with isogenic mutants in the genetic reference strain PAO1. In PAO1, we show that deletion of rhlR has a much more significant impact on the expression of a wide range of virulence associated factors rather than deletion of lasR. In PA80, no QS regulatory genes were expressed, which we attribute to the inactivation of the RhlRI QS system by deletion of rhlR and mutation of rhlI. This study demonstrates that inactivation of the LasRI system does not impact RhlRI regulated virulence factors. PA80 has bypassed the common pathoadaptive mutations observed in LasR by targeting the RhlRI system. This suggests that RhlRI is a significant target for the long-term persistence of P. aeruginosa in chronic CF patients. This raises important questions in targeting QS systems for therapeutic interventions.

Activities of Tobramycin and Six Other Antibiotics against Pseudomonas aeruginosa Isolates from Patients with Cystic Fibrosis

1999 ◽  
Vol 43 (12) ◽  
pp. 2877-2880 ◽  
Author(s):  
Ribhi M. Shawar ◽  
David L. MacLeod ◽  
Richard L. Garber ◽  
Jane L. Burns ◽  
Jenny R. Stapp ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Active Drug ◽  
Resistance Mechanisms ◽  
Phase Iii ◽  
In Vitro Activity ◽  
Phase Iii Clinical Trials ◽  
Multiple Antibiotics

ABSTRACT The in vitro activity of tobramycin was compared with those of six other antimicrobial agents against 1,240 Pseudomonas aeruginosa isolates collected from 508 patients with cystic fibrosis during pretreatment visits as part of the phase III clinical trials of tobramycin solution for inhalation. The tobramycin MIC at which 50% of isolates are inhibited (MIC50) and MIC90 were 1 and 8 μg/ml, respectively. Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to tobramycin (5.4%) than to ceftazidime (11.1%), aztreonam (11.9%), amikacin (13.1%), ticarcillin (16.7%), gentamicin (19.3%), or ciprofloxacin (20.7%). For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. Of 56 isolates for which the tobramycin MIC was ≥16 μg/ml and that were investigated for resistance mechanisms, only 7 (12.5%) were shown to possess known aminoglycoside-modifying enzymes; the remaining were presumably resistant by an incompletely understood mechanism often referred to as “impermeability.”

scholarly journals Epidemiology of cystic fibrosis respiratory pathogens isolated at a South African Hospital, 2006–2010

2016 ◽  
Vol 31 (4) ◽  
pp. 106-111
Author(s):  
Vindana Chibabhai ◽  
Warren Lowman
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
South African ◽  
Burkholderia Cepacia ◽  
Stenotrophomonas Maltophilia ◽  
Burkholderia Cepacia Complex ◽  
Respiratory Pathogens ◽  
Academic Hospital ◽  
Cystic Fibrosis Population ◽  
Susceptibility Patterns

Background: The epidemiology of cystic fibrosis (CF) associated pathogens other than Pseudomonas aeruginosa in the South African cystic fibrosis population has not been previously described.Methods: A retrospective review of respiratory cultures taken from cystic fibrosis clinic patients at the Charlotte Maxeke Johannesburg Academic Hospital from 2006 to 2010 was performed.Results: During the study period, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia complex and Candida albicans prevalence remained stable, Aspergillus fumigatus increased from 8% to 20% (p = 0.0132); Staphylococcus aureus decreased from 66% to 50% (p = 0.0243) and Haemophilus influenzae decreased from 13% to 3% (p = 0.0136). There were significant antimicrobial susceptibility changes to meropenem (p  0.0001) amongst P. aeruginosa isolates and cloxacillin (p 0.0001) amongst S. aureus isolates. Prevalence of most bacterial pathogens appeared to increase with increasing age.Conclusion: The findings of this study illustrate the epidemiology of CF associated respiratory pathogens and the trends in prevalence and susceptibility patterns over a 5-year period.

scholarly journals Antimicrobial susceptibility of Pasteurella multocida isolated from sheep and pigs in Spain – Short communication

2019 ◽  
Vol 67 (4) ◽  
pp. 489-498
Author(s):  
Dolores Cid ◽  
José Francisco Fernández-Garayzábal ◽  
Chris Pinto ◽  
Lucas Domínguez ◽  
Ana Isabel Vela
Keyword(s):  
High Resistance ◽  
Antimicrobial Susceptibility ◽  
Pasteurella Multocida ◽  
Antimicrobial Agents ◽  
Empirical Therapy ◽  
Microdilution Method ◽  
Low Levels ◽  
Resistance Rates ◽  
Farming Industry ◽  
Susceptibility Patterns

Pasteurella multocida is responsible for economically important diseases in sheep and pigs. Antimicrobial susceptibility studies are essential for initiating rational and effective empirical therapy of P. multocida infections. In this study we investigated the antimicrobial susceptibility to 18 antimicrobial agents of 156 clinical isolates of P. multocida from sheep (n = 87) and pigs (n = 69) using the microdilution method. Both sheep and pig isolates exhibited low levels of resistance (≤ 15%) to ceftiofur, gentamicin, neomycin, spectinomycin, chlortetracycline, tulathromycin, florfenicol, danofloxacin, and enrofloxacin and trimethoprim/sulphamethoxazole, high resistance rates (> 15% up to 50%) to oxytetracycline, tilmicosin, and tiamulin, and very high resistance rates (> 50%) to tylosin tartrate, clindamycin, and sulphadimethoxine. However, sheep isolates exhibited significantly lower percentages of resistance and lower MIC90 values (P < 0.05) than pig isolates for most of the antimicrobials tested. In addition, sheep isolates exhibited also significantly lower phenotypic antimicrobial resistance diversity (8 resistotypes vs. 30 resistotypes). LAC-LIN-SUL-MAC was the resistotype most frequently detected in sheep (39.1%) and LIN-SUL-MAC in pig isolates (26.1%). The differences in susceptibility patterns could be influenced by the lower use of antimicrobials in the small ruminant industry compared with the pig farming industry.

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