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In Vitro Activities of Nisin and Nisin Derivatives Alone and In Combination with Antibiotics against Staphylococcus Biofilms.

Field D, O' Connor R, Cotter PD, Ross RP, Hill C - Front Microbiol (2016)

Bottom Line: Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone.Furthermore, the metabolic activity of established biofilms treated with nisin V + chloramphenicol and nisin I4V + chloramphenicol combinations revealed a significant decrease in S. aureus SA113 and S. pseudintermedius DSM21284 biofilm viability, respectively, compared to the nisin A + antibiotic combinations as determined by the rapid colorimetric XTT assay.The results indicate that the activities of the nisin derivative and antibiotic combinations represent a significant improvement over that of the wild-type nisin and antibiotic combination and merit further investigation with a view to their use as anti-biofilm agents.

View Article: PubMed Central - PubMed

Affiliation: School of Microbiology, University College Cork Cork, Ireland.

ABSTRACT
The development and spread of pathogenic bacteria that are resistant to the existing catalog of antibiotics is a major public health threat. Biofilms are complex, sessile communities of bacteria embedded in an organic polymer matrix which serve to further enhance antimicrobial resistance. Consequently, novel compounds and innovative methods are urgently required to arrest the proliferation of drug-resistant infections in both nosocomial and community environments. Accordingly, it has been suggested that antimicrobial peptides could be used as novel natural inhibitors that can be used in formulations with synergistically acting antibiotics. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many Gram-positive bacteria. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, staphylococci, and streptococci associated with bovine mastitis. We have also identified nisin derivatives with an enhanced ability to impair biofilm formation and to reduce the density of established biofilms of methicillin resistant S. pseudintermedius. The present study was aimed at evaluating the potential of nisin and nisin derivatives to increase the efficacy of conventional antibiotics and to assess the possibility of killing and/or eradicating biofilm-associated cells of a variety of staphylococcal targets. Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone. Furthermore, the metabolic activity of established biofilms treated with nisin V + chloramphenicol and nisin I4V + chloramphenicol combinations revealed a significant decrease in S. aureus SA113 and S. pseudintermedius DSM21284 biofilm viability, respectively, compared to the nisin A + antibiotic combinations as determined by the rapid colorimetric XTT assay. The results indicate that the activities of the nisin derivative and antibiotic combinations represent a significant improvement over that of the wild-type nisin and antibiotic combination and merit further investigation with a view to their use as anti-biofilm agents.

No MeSH data available.


Related in: MedlinePlus

Viability of biofilms of (A)S. aureus SA113 untreated, and treated with 6X MIC (15μM) of nisin A, nisin V (M21V), and nisin I4V and peptides alone and in combination with 2X MIC chloramphenicol for 24 h and (B)S. pseudintermedius DSM 21284 treated with 4X MIC (1.25 μM) of nisin A, nisin V (M21V), and nisin I4V peptides alone and in combination with 1X MIC chloramphenicol for 24 h as evaluated by XTT (2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) assay measured using a microtiter plate reader. The means and standard deviations of triplicate determinations are presented. Asterisks indicate statistically significant differences (Student’s t-test) between peptide and antibiotic combinations used at similar concentration (∗∗∗p < 0.001).
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Figure 4: Viability of biofilms of (A)S. aureus SA113 untreated, and treated with 6X MIC (15μM) of nisin A, nisin V (M21V), and nisin I4V and peptides alone and in combination with 2X MIC chloramphenicol for 24 h and (B)S. pseudintermedius DSM 21284 treated with 4X MIC (1.25 μM) of nisin A, nisin V (M21V), and nisin I4V peptides alone and in combination with 1X MIC chloramphenicol for 24 h as evaluated by XTT (2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) assay measured using a microtiter plate reader. The means and standard deviations of triplicate determinations are presented. Asterisks indicate statistically significant differences (Student’s t-test) between peptide and antibiotic combinations used at similar concentration (∗∗∗p < 0.001).

Mentions: In view of the enhanced inhibitory effect of nisin, nisin V, and nisin I4V derivatives + chloramphenicol combinations against vegetative cells of S. aureus SA113 (Figure 1A), we sought to determine if these combinations could also be effective against pre-formed biofilms. Following preliminary experiments with 1X, 2X, 4X, and 6X MIC of nisin and chloramphenicol alone (data not shown), biofilms of S. aureus SA113 formed on a 96-well plate were incubated with nisin and nisin derivative peptides at a concentration of 6X MIC (15 μM; 50.2 μg/ml), chloramphenicol at 2X MIC (8 μg/ml) and combinations thereof for 24 h. The results revealed that while chloramphenicol alone had no significant effect (p = 0.2156) compared to the untreated control, nisin, and nisin variants as well as the peptide/antibiotic combinations did result in a significant decrease in biofilm viability compared to the untreated control (Figure 4A). Notably, the metabolic activity of biofilms treated with nisin V + chloramphenicol and I4V + chloramphenicol combinations was significantly diminished (p = 0.0002 and p = 0.0005, respectively) compared to the nisin A + chloramphenicol treatment. Indeed, this result was in agreement with the observed enhanced effect with similar peptide/antibiotic combinations in growth curve analysis against vegetative cells of S. aureus SA113 (Figure 1A).


In Vitro Activities of Nisin and Nisin Derivatives Alone and In Combination with Antibiotics against Staphylococcus Biofilms.

Field D, O' Connor R, Cotter PD, Ross RP, Hill C - Front Microbiol (2016)

Viability of biofilms of (A)S. aureus SA113 untreated, and treated with 6X MIC (15μM) of nisin A, nisin V (M21V), and nisin I4V and peptides alone and in combination with 2X MIC chloramphenicol for 24 h and (B)S. pseudintermedius DSM 21284 treated with 4X MIC (1.25 μM) of nisin A, nisin V (M21V), and nisin I4V peptides alone and in combination with 1X MIC chloramphenicol for 24 h as evaluated by XTT (2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) assay measured using a microtiter plate reader. The means and standard deviations of triplicate determinations are presented. Asterisks indicate statistically significant differences (Student’s t-test) between peptide and antibiotic combinations used at similar concentration (∗∗∗p < 0.001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834297&req=5

Figure 4: Viability of biofilms of (A)S. aureus SA113 untreated, and treated with 6X MIC (15μM) of nisin A, nisin V (M21V), and nisin I4V and peptides alone and in combination with 2X MIC chloramphenicol for 24 h and (B)S. pseudintermedius DSM 21284 treated with 4X MIC (1.25 μM) of nisin A, nisin V (M21V), and nisin I4V peptides alone and in combination with 1X MIC chloramphenicol for 24 h as evaluated by XTT (2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) assay measured using a microtiter plate reader. The means and standard deviations of triplicate determinations are presented. Asterisks indicate statistically significant differences (Student’s t-test) between peptide and antibiotic combinations used at similar concentration (∗∗∗p < 0.001).
Mentions: In view of the enhanced inhibitory effect of nisin, nisin V, and nisin I4V derivatives + chloramphenicol combinations against vegetative cells of S. aureus SA113 (Figure 1A), we sought to determine if these combinations could also be effective against pre-formed biofilms. Following preliminary experiments with 1X, 2X, 4X, and 6X MIC of nisin and chloramphenicol alone (data not shown), biofilms of S. aureus SA113 formed on a 96-well plate were incubated with nisin and nisin derivative peptides at a concentration of 6X MIC (15 μM; 50.2 μg/ml), chloramphenicol at 2X MIC (8 μg/ml) and combinations thereof for 24 h. The results revealed that while chloramphenicol alone had no significant effect (p = 0.2156) compared to the untreated control, nisin, and nisin variants as well as the peptide/antibiotic combinations did result in a significant decrease in biofilm viability compared to the untreated control (Figure 4A). Notably, the metabolic activity of biofilms treated with nisin V + chloramphenicol and I4V + chloramphenicol combinations was significantly diminished (p = 0.0002 and p = 0.0005, respectively) compared to the nisin A + chloramphenicol treatment. Indeed, this result was in agreement with the observed enhanced effect with similar peptide/antibiotic combinations in growth curve analysis against vegetative cells of S. aureus SA113 (Figure 1A).

Bottom Line: Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone.Furthermore, the metabolic activity of established biofilms treated with nisin V + chloramphenicol and nisin I4V + chloramphenicol combinations revealed a significant decrease in S. aureus SA113 and S. pseudintermedius DSM21284 biofilm viability, respectively, compared to the nisin A + antibiotic combinations as determined by the rapid colorimetric XTT assay.The results indicate that the activities of the nisin derivative and antibiotic combinations represent a significant improvement over that of the wild-type nisin and antibiotic combination and merit further investigation with a view to their use as anti-biofilm agents.

View Article: PubMed Central - PubMed

Affiliation: School of Microbiology, University College Cork Cork, Ireland.

ABSTRACT
The development and spread of pathogenic bacteria that are resistant to the existing catalog of antibiotics is a major public health threat. Biofilms are complex, sessile communities of bacteria embedded in an organic polymer matrix which serve to further enhance antimicrobial resistance. Consequently, novel compounds and innovative methods are urgently required to arrest the proliferation of drug-resistant infections in both nosocomial and community environments. Accordingly, it has been suggested that antimicrobial peptides could be used as novel natural inhibitors that can be used in formulations with synergistically acting antibiotics. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many Gram-positive bacteria. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, staphylococci, and streptococci associated with bovine mastitis. We have also identified nisin derivatives with an enhanced ability to impair biofilm formation and to reduce the density of established biofilms of methicillin resistant S. pseudintermedius. The present study was aimed at evaluating the potential of nisin and nisin derivatives to increase the efficacy of conventional antibiotics and to assess the possibility of killing and/or eradicating biofilm-associated cells of a variety of staphylococcal targets. Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone. Furthermore, the metabolic activity of established biofilms treated with nisin V + chloramphenicol and nisin I4V + chloramphenicol combinations revealed a significant decrease in S. aureus SA113 and S. pseudintermedius DSM21284 biofilm viability, respectively, compared to the nisin A + antibiotic combinations as determined by the rapid colorimetric XTT assay. The results indicate that the activities of the nisin derivative and antibiotic combinations represent a significant improvement over that of the wild-type nisin and antibiotic combination and merit further investigation with a view to their use as anti-biofilm agents.

No MeSH data available.


Related in: MedlinePlus