scholarly journals Effect of Simulated Gastrointestinal Conditions on Biofilm Formation bySalmonella1,4,[5],12:i:-

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
R. Seixas ◽  
M. Gabriel ◽  
J. Machado ◽  
L. Tavares ◽  
F. Bernardo ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Biofilm Formation ◽  
Contributing Factors ◽  
Biofilm Growth ◽  
Biofilm Production ◽  
Gastrointestinal Conditions ◽  
Mueller Hinton ◽  
Mueller Hinton Broth

SalmonellaTyphimurium 1,4,[5],12:i:- is a major serovar responsible for human salmonellosis whose biofilm-forming ability, influenced by environmental conditions like those found in the gastrointestinal tract, is one of the main contributing factors to its ability to persist in the host and thus one of the main causes of chronic relapsing infections. Most studies to evaluate biofilm formation are performed in microtiter assays using standard media. However, no reports are available on the ability of this serovar to produce biofilm underin vitrosimulated gastrointestinal conditions which better correlate with the environment found in the gastrointestinal tract. To address this, a modified biofilm assay simulating intestinal fluid was conceived to assess the biofilm formation of 133SalmonellaTyphimurium 1,4,[5],12:i:- isolates with and without agitation and at three different time points (24 h, 48 h, and 72 h). The results were then compared to the existing microtiter method using conventional biofilm growth medium (Mueller Hinton Broth). Statistical analysis revealed significant differences in the results obtained between the three protocols used. The simulated human intestinal environment impaired biofilm production demonstrating that conditions like pH, agitation or the presence of enzymes can influence biofilm production. Therefore, results fromin vitrosimulation ofin vivoconditions may contribute to unravelling factors relating to biofilm formation and persistence in the context of the human host.

scholarly journals Role of Sialic Acid and Complex Carbohydrate Biosynthesis in Biofilm Formation by Nontypeable Haemophilus influenzae in the Chinchilla Middle Ear

2005 ◽  
Vol 73 (6) ◽  
pp. 3210-3218 ◽  
Author(s):  
Joseph Jurcisek ◽  
Laura Greiner ◽  
Hiroshi Watanabe ◽  
Anthony Zaleski ◽  
Michael A. Apicella ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Haemophilus Influenzae ◽  
Middle Ear ◽  
Biofilm Formation ◽  
Mammalian Host ◽  
Nontypeable Haemophilus Influenzae ◽  
Biofilm Production ◽  
Tract Infections

ABSTRACT Nontypeable Haemophilus influenzae (NTHI) is an important pathogen in respiratory tract infections, including otitis media (OM). NTHI forms biofilms in vitro as well as in the chinchilla middle ear, suggesting that biofilm formation in vivo might play an important role in the pathogenesis and chronicity of OM. We've previously shown that SiaA, SiaB, and WecA are involved in biofilm production by NTHI in vitro. To investigate whether these gene products were also involved in biofilm production in vivo, NTHI strain 2019 and five isogenic mutants with deletions in genes involved in carbohydrate biosynthesis were inoculated into the middle ears of chinchillas. The wild-type strain formed a large, well-organized, and viable biofilm; however, the wecA, lsgB, siaA, pgm, and siaB mutants were either unable to form biofilms or formed biofilms of markedly reduced mass, organization, and viability. Despite their compromised ability to form a biofilm in vivo, wecA, lsgB, and siaA mutants survived in the chinchilla, inducing culture-positive middle ear effusions, whereas pgm and siaB mutants were extremely sensitive to the bactericidal activity of chinchilla serum and thus did not survive. Lectin analysis indicated that sialic acid was an important component of the NTHI 2019 biofilm produced in vivo. Our data suggested that genes involved in carbohydrate biosynthesis and assembly play an important role in the ability of NTHI to form a biofilm in vivo. Collectively, we found that when modeled in a mammalian host, whereas biofilm formation was not essential for survivability of NTHI in vivo, lipooligosaccharide sialylation was indispensable.

scholarly journals In vitro Antimicrobial Potency of Lemon Fruit (Citrus limon) Extract on Salmonella typhi

2020 ◽  
Vol 11 (2) ◽  
pp. 69
Author(s):  
Farhan Haidar Fazlur Rahman ◽  
Lindawati Alimsardjono ◽  
Sunarni Zakaria
Keyword(s):  
Agar Plate ◽  
Antimicrobial Effect ◽  
Salmonella Typhi ◽  
Citrus Limon ◽  
Lemon Fruit ◽  
Mueller Hinton ◽  
Antibacterial Spectrum ◽  
Mueller Hinton Broth

Introduction: This study aimed to evaluate minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of lemon fruit (Citrus limon) extract in inhibiting Salmonella typhi growth in vitro.Methods: This research was categorized as a laboratory experimental study. Lemon fruit (Citrus limon) extract was prepared with concentration as follows: 100.000 ppm, 50.000 ppm, 25.000 ppm, 12.500 ppm, 6.250 ppm, 3.125 ppm, 1.562 ppm, 781 ppm, and 390 ppm. Dilution tests with Mueller-Hinton broth medium were performed to determine the MIC. After 24 hours of incubation, isolated Salmonella typhi inside the tube was inoculated back in MacConkey agar plate medium to determine the MBC. Replications were conducted 3 times according to Federer’s formula.Results: MIC of lemon fruit (Citrus limon) extract to Salmonella typhi was determined at 3.125 ppm. Meanwhile, MBC was determined at 6.250 ppm.Conclusion: This study showed the potential antimicrobial effect of lemon fruit (Citrus limon) extract against Salmonella typhi in-vitro. Further studies are still needed to determine its efficacy and safety in vivo and also its full antibacterial spectrum. 

The paradoxical in vivo activity of β-lactams against metallo-β-lactamase-producing Enterobacterales is not restricted to carbapenems

2020 ◽  
Author(s):  
Kamilia Abdelraouf ◽  
Sergio Reyes ◽  
David P Nicolau
Keyword(s):  
Infection Model ◽  
Murine Models ◽  
Mueller Hinton ◽  
Fold Reduction ◽  
Testing Medium ◽  
Zinc Concentrations ◽  
Mueller Hinton Broth ◽  
Positive Controls

Abstract Background Using murine models of infection, we previously reported the potent in vivo activity of carbapenems against MBL-producing Enterobacterales despite the observed resistance in vitro. In the current study, we examined the in vivo activity of a cefepime human-simulated regimen against MBL-producing Enterobacterales in a murine thigh infection model. Methods A population of clinical isolates and isogenic engineered MBL-producing Enterobacterales transformants expressing MBLs but no detectable cefepime-hydrolysing serine β-lactamases were utilized. KPC-producing isolates were included as positive controls. Cefepime, piperacillin/tazobactam and meropenem MICs were determined using broth microdilution in conventional CAMHB and EDTA-supplemented (zinc-limited) broth. In vivo efficacy of a cefepime human-simulated regimen (2 g q8h as a 2 h infusion) was determined in the neutropenic murine thigh infection model against the test strains. Efficacy was measured as the change in log10 cfu/thigh at 24 h compared with 0 h controls. Results MBL-producing Enterobacterales strains were found to be cefepime, piperacillin/tazobactam and meropenem non-susceptible in conventional broth. Supplementation with EDTA at a concentration of 300 mg/L resulted in multi-fold reduction in the MICs and restoration of susceptibility. In accordance with the MICs generated in zinc-limited broth, administration of a cefepime human-simulated regimen was associated with substantial bacterial reductions among mice infected with MBL-producing Enterobacterales. Absence of MIC reduction in zinc-limited broth and lack of efficacy among mice infected with KPC-producing isolates were observed. Conclusions For MBL-producing Enterobacterales, susceptibility testing with Mueller–Hinton broth, a zinc-rich testing medium, is flawed since it does not recapitulate the host environment, in which zinc concentrations are low.

scholarly journals High Levels of Genetic Recombination during Nasopharyngeal Carriage and Biofilm Formation in Streptococcus pneumoniae

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Laura R. Marks ◽  
Ryan M. Reddinger ◽  
Anders P. Hakansson
Keyword(s):  
Biofilm Formation ◽  
Transformation Efficiency ◽  
Genetic Exchange ◽  
Biofilm Growth ◽  
High Transformation ◽  
Lower Temperature ◽  
Multiple Strains

ABSTRACTTransformation of genetic material between bacteria was first observed in the 1920s usingStreptococcus pneumoniaeas a model organism. Since then, the mechanism of competence induction and transformation has been well characterized, mainly using planktonic bacteria or septic infection models. However, epidemiological evidence suggests that genetic exchange occurs primarily during pneumococcal nasopharyngeal carriage, which we have recently shown is associated with biofilm growth, and is associated with cocolonization with multiple strains. However, no studies to date have comprehensively investigated genetic exchange during cocolonizationin vitroandin vivoor the role of the nasopharyngeal environment in these processes. In this study, we show that genetic exchange during dual-strain carriagein vivois extremely efficient (10−2) and approximately 10,000,000-fold higher than that measured during septic infection (10−9). This high transformation efficiency was associated with environmental conditions exclusive to the nasopharynx, including the lower temperature of the nasopharynx (32 to 34°C), limited nutrient availability, and interactions with epithelial cells, which were modeled in a novel biofilm modelin vitrothat showed similarly high transformation efficiencies. The nasopharyngeal environmental factors, combined, were critical for biofilm formation and induced constitutive upregulation of competence genes and downregulation of capsule that promoted transformation. In addition, we show that dual-strain carriagein vivoand biofilms formedin vitrocan be transformed during colonization to increase their pneumococcal fitness and also, importantly, that bacteria with lower colonization ability can be protected by strains with higher colonization efficiency, a process unrelated to genetic exchange.IMPORTANCEAlthough genetic exchange between pneumococcal strains is known to occur primarily during colonization of the nasopharynx and colonization is associated with biofilm growth, this is the first study to comprehensively investigate transformation in this environment and to analyze the role of environmental and bacterial factors in this process. We show that transformation efficiency during cocolonization by multiple strains is very high (around 10−2). Furthermore, we provide novel evidence that specific aspects of the nasopharyngeal environment, including lower temperature, limited nutrient availability, and epithelial cell interaction, are critical for optimal biofilm formation and transformation efficiency and result in bacterial protein expression changes that promote transformation and fitness of colonization-deficient strains. The results suggest that cocolonization in biofilm communities may have important clinical consequences by facilitating the spread of antibiotic resistance and enabling serotype switching and vaccine escape as well as protecting and retaining poorly colonizing strains in the pneumococcal strain pool.

scholarly journals 607. Scope and Predictive Genetic/Phenotypic Signatures of “Bicarbonate [NaHCO3]-Responsivity” and β-Lactam Sensitization among Methicillin-Resistant Staphylococcus aureus (MRSA)

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S284-S284
Author(s):  
Selvi Ceren. Ersoy ◽  
Brianne Zapata-Davila ◽  
Mariam Otmishi ◽  
Vanessa Milan ◽  
Liang Li ◽  
...  
Keyword(s):  
Methicillin Resistant Staphylococcus Aureus ◽  
Clonal Complex ◽  
Broth Microdilution ◽  
Standard Medium ◽  
Mueller Hinton ◽  
Solid Foundation ◽  
Mrsa Strains ◽  
Mueller Hinton Broth

Abstract Background Selected MRSA strains become susceptible to β-lactams (e.g., oxacillin [OX]; cefazolin [CFZ]) in vitro when tested in a standard medium (cation-adjusted Mueller–Hinton Broth; CA-MHB) supplemented with NaHCO3 (“NaHCO3-responsivity”). In vivo activity of β-lactams was demonstrated for MRSA strains with this phenotype in a rabbit endocarditis model (Ersoy et al Antimicrob Agents Chemother 2019). The current study was designed to: (i) determine the prevalence of the NaHCO3-responsive phenotype in a large collection of clinical MRSA isolates; and (ii) identify genetic and phenotypic predictors of this phenotype. Methods. 58 recent MRSA bloodstream isolates representing contemporary clonal complex (CC) genotypes were screened for the NaHCO3-responsive phenotype by broth microdilution MICs in CA-MHB, with or without NaHCO3 supplementation (25–44 mM). Methods 58 recent MRSA bloodstream isolates representing contemporary clonal complex (CC) genotypes were screened for the NaHCO3-responsive phenotype by broth microdilution MICs in CA-MHB, with or without NaHCO3 supplementation (25–44 mM). Results 43/58 (74.1%) and 21/58 (36.2%) were rendered susceptible to CFZ and OX, respectively, in the presence of NaHCO3; 20 of the 21 OX-susceptible strains were also susceptible to CFZ in the presence of NaHCO3. High baseline β-lactam MICs (i.e., MICs in CA-MHB alone ≥64 µg/mL) was not predictive of NaHCO3 responsivity. The CC8 genotype was correlated with NaHCO3 responsivity for OX, but not CFZ (P < 0.05). Conclusion The NaHCO3-responsive phenotype is relatively common for both OX and especially CFZ among clinical MRSA isolates. Identification of specific genetic factors linked to this phenotype remains ongoing. Confirmation in relevant animal models that this phenotype is predictive of β-lactam efficacy in vivo could provide a solid foundation for a paradigm shift in antimicrobial susceptibility testing of MRSA. Disclosures All authors: No reported disclosures.

scholarly journals Assessment of Ceragenins in Prevention of Damage to Voice Prostheses Caused by Candida Biofilm Formation

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1371
Author(s):  
Jakub Spałek ◽  
Tamara Daniluk ◽  
Adrian Godlewski ◽  
Piotr Deptuła ◽  
Urszula Wnorowska ◽  
...  
Keyword(s):  
Candida Species ◽  
Biofilm Formation ◽  
Significant Proportion ◽  
Life Quality ◽  
Ethanol Solution ◽  
In Vivo Studies ◽  
Biofilm Growth ◽  
Voice Prostheses

This study aimed to investigate the potential application of ceragenins (CSAs) as new candidacidal agents to prevent biofilm formation on voice prostheses (VPs). The deterioration of the silicone material of VPs is caused by biofilm growth on the device which leads to frequent replacement procedures and sometimes serious complications. A significant proportion of these failures is caused by Candida species. We found that CSAs have significant candidacidal activities in vitro (MIC; MFC; MBIC), and they effectively eradicate species of yeast responsible for VP failure. Additionally, in our in vitro experimental setting, when different Candida species were subjected to CSA-13 and CSA-131 during 25 passages, no tested Candida strain showed the significant development of resistance. Using liquid chromatography–mass spectrometry (LC-MS), we found that VP immersion in an ethanol solution containing CSA-131 results in silicon impregnation with CSA-131 molecules, and in vitro testing revealed that fungal biofilm formation on such VP surfaces was inhibited by embedded ceragenins. Future in vivo studies will validate the use of ceragenin-coated VP for improvement in the life quality and safety of patients after a total laryngectomy.

scholarly journals Pharmacodynamic Profiling of a Siderophore-Conjugated Monocarbam in Pseudomonas aeruginosa: Assessing the Risk for Resistance and Attenuated Efficacy

2015 ◽  
Vol 59 (12) ◽  
pp. 7743-7752 ◽  
Author(s):  
Aryun Kim ◽  
Amy Kutschke ◽  
David E. Ehmann ◽  
Sara A. Patey ◽  
Jared L. Crandon ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Body Weight ◽  
Iron Uptake ◽  
Threshold Concentration ◽  
Content Type ◽  
Adaptive Resistance ◽  
Mueller Hinton ◽  
Mueller Hinton Broth

ABSTRACTThe objective of this study was to investigate the risk of attenuated efficacy due to adaptive resistance for the siderophore-conjugated monocarbam SMC-3176 inPseudomonas aeruginosaby using a pharmacokinetic/pharmacodynamic (PK/PD) approach. MICs were determined in cation-adjusted Mueller-Hinton broth (MHB) and in Chelex-treated, dialyzed MHB (CDMHB). Spontaneous resistance was assessed at 2× to 16× the MIC and the resulting mutants sequenced. Efficacy was evaluated in a neutropenic mouse thigh model at 3.13 to 400 mg/kg of body weight every 3 h for 24 h and analyzed for association with free time above the MIC (fT>MIC). To closer emulate the conditions of thein vivomodel, we developed a novel assay testing activity mouse whole blood (WB). All mutations were found in genes related to iron uptake:piuA,piuC,pirR,fecI, andpvdS. Against fourP. aeruginosaisolates, SMC-3176 displayed predictable efficacy corresponding to thefT>MIC using the MIC in CDMHB (R2= 0.968 to 0.985), with stasis to 2-log kill achieved at 59.4 to 81.1%. Efficacy did not translate forP. aeruginosaisolate JJ 4-36, as thein vivoresponses were inconsistent withfT>MIC exposures and implied a threshold concentration that was greater than the MIC. The results of the mouse WB assay indicated that efficacy was not predictable using the MIC for JJ 4-36 and four additional isolates, against whichin vivofailures of another siderophore-conjugated β-lactam were previously reported. SMC-3176 carries a risk of attenuated efficacy inP. aeruginosadue to rapid adaptive resistance preventing entry via the siderophore-mediated iron uptake systems. Substantialin vivotesting is warranted for compounds using the siderophore approach to thoroughly screen for thisin vitro-in vivodisconnect inP. aeruginosa.

Biofilm-formation by Staphylococcus aureus and Staphylococcus epidermidis isolates from subclinical mastitis in conditions mimicking the udder environment

2015 ◽  
Vol 18 (4) ◽  
pp. 787-792 ◽  
Author(s):  
R. Seixas ◽  
D. Varanda ◽  
R. Bexiga ◽  
L. Tavares ◽  
M. Oliveira
Keyword(s):  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Bovine Mastitis ◽  
Subclinical Mastitis ◽  
Protective Role ◽  
Dynamic Conditions ◽  
Biofilm Production ◽  
Static Conditions

AbstractStaphylococcusis the genus most commonly isolated from bovine mastitis in many countries. It may express several virulence factors including biofilm formation, which may protect the bacterial community from antimicrobials’ action, preventing these compounds from reaching its interior, where they reach subinhibitory concentrations (subMIC).Most biofilm production assays are performed in static conditions, while studies regarding antimicrobial resistance usually do not resemble the udder environment because they are performed at high concentrations. In this study we evaluated the influence of dynamic conditions and media, including Mueller Hinton Broth (MHB) and UHT whole milk (WM), as well as the effect of subMIC concentrations of five different antimicrobial agents on biofilm formation by staphylococci isolated from subclinical mastitis. Results suggest that dynamic conditions and media may influence biofilm formation and revealed that milking simulation may significantly increase biofilm production. Sub-MIC concentrations decrease biofilm formation in MHB but increase in WM, suggesting a protective role of milk against antimicrobial compounds’ action. Therefore,in vitroconditions that simulate the udder environment andin vivoconditions should be included as one of the parameters in evaluation of biofilm producing strains, in order to provide more reliable results.

scholarly journals Sinefungin, a Natural Nucleoside Analogue of S-Adenosylmethionine, InhibitsStreptococcus pneumoniaeBiofilm Growth

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mukesh Kumar Yadav ◽  
Seok-Won Park ◽  
Sung-Won Chae ◽  
Jae-Jun Song
Keyword(s):  
Nucleoside Analogue ◽  
Biofilm Formation ◽  
Gene Expressions ◽  
Biofilm Growth ◽  
Autoinducer 2 ◽  
The Matrix ◽  
Pneumococcal Colonization ◽  
Antibiofilm Agents

Pneumococcal colonization and disease is often associated with biofilm formation, in which the bacteria exhibit elevated resistance both to antibiotics and to host defense systems, often resulting in infections that are persistent and difficult to treat. We evaluated the effect of sinefungin, a nucleoside analogue of S-adenosylmethionine, on pneumococcalin vitrobiofilm formation andin vivocolonization. Sinefungin is bacteriostatic to pneumococci and significantly decreased biofilm growth and inhibited proliferation and structure of actively growing biofilms but did not alter growth or the matrix structure of established biofilms. Sinefungin significantly reduced pneumococcal colonization in rat middle ear. The quorum sensing molecule (autoinducer-2) production was significantly reduced by 92% in sinefungin treated samples. TheluxS, pfs, andspeEgenes were downregulated in biofilms grown in the presence of sinefungin. This study shows that sinefungin inhibits pneumococcal biofilm growthin vitroand colonizationin vivo, decreases AI-2 production, and downregulatesluxS,pfs, andspeEgene expressions. Therefore, the S-adenosylmethionine (SAM) inhibitors could be used as lead compounds for the development of novel antibiofilm agents against pneumococci.

scholarly journals Protegrin-1: a broad-spectrum, rapidly microbicidal peptide with in vivo activity.

1997 ◽  
Vol 41 (8) ◽  
pp. 1738-1742 ◽  
Author(s):  
D A Steinberg ◽  
M A Hurst ◽  
C A Fujii ◽  
A H Kung ◽  
J F Ho ◽  
...  
Keyword(s):  
Serial Passage ◽  
Vehicle Control ◽  
Control Group ◽  
Vehicle Control Group ◽  
Mueller Hinton ◽  
Immunocompetent Mice ◽  
Systemic Infections ◽  
Mueller Hinton Broth

Protegrin-1 (PG-1) is a cysteine-rich, 18-residue beta-sheet peptide isolated from porcine leukocytes with antimicrobial activity against a broad range of microorganisms. The MICs of PG-1 against representative gram-positive and gram-negative bacteria ranged from 0.12 to 2 microg/ml. At these levels, PG-1 was rapidly bactericidal in vitro, reducing the number of viable CFU of either methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa by more than three log units in less than 15 min. Resistance to PG-1 did not develop after 11 subculturings of P. aeruginosa or 18 subcultures of MRSA in Mueller-Hinton broth containing PG-1 at one-half the MIC. Under similar conditions of serial passage, the MICs of norfloxacin and gentamicin against P. aeruginosa increased 10 and 190 times, respectively. Similarly, the MIC of norfloxacin against MRSA increased 85 times. Immunocompetent mice inoculated intraperitoneally (i.p.) with P. aeruginosa or S. aureus exhibited 93 to 100% mortality in the vehicle control group compared with 0 to 27% mortality in animals that received a single i.p. injection of PG-1 (0.5 mg/kg of body weight). Mice inoculated with S. aureus by intravenous (i.v.) injection and dosed 0 to 60 min later with a single i.v. injection of PG-1 (5 mg/kg) had a mortality of 7 to 33%, compared to a mortality of 73 to 93% in the vehicle controls. In leukopenic mice inoculated i.v. with vancomycin-resistant Enterococcus faecium, mortality was 87% in the vehicle control group and 33% in animals that received a single i.v. injection of PG-1 (2.5 mg/kg). Taken together, these data indicate that PG-1 has potential for use as an antimicrobial agent in the treatment of local or systemic infections caused by clinically relevant pathogens.

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