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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

Growth curve analysis of Staphylococcus aureus SA113 in the presence of nisin A (A), nisin V (V), and nisin I4V (I4V) peptides (0.937 μM; 3.0 μg/ml) and in combination with 1.5 μg/ml chloramphenicol (Cm), 5.0 μg/ml vancomycin (Van) and 0.005 μg/ml penicillin (Pen). The means and standard deviations of three independent determinations are presented.
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Figure 1: Growth curve analysis of Staphylococcus aureus SA113 in the presence of nisin A (A), nisin V (V), and nisin I4V (I4V) peptides (0.937 μM; 3.0 μg/ml) and in combination with 1.5 μg/ml chloramphenicol (Cm), 5.0 μg/ml vancomycin (Van) and 0.005 μg/ml penicillin (Pen). The means and standard deviations of three independent determinations are presented.

Mentions: Having established the MIC values for a range of antibiotics against the representative staphylococci, growth curves were performed in order to reveal more subtle features of the impact of sub-lethal concentrations of nisin A, nisin V, and nisin I4V alone, but also in combination with a selection of antibiotics on bacterial growth. The final concentration of nisin used for each organism was determined on the basis of MIC results obtained previously against these indicator strains (Field et al., 2010, 2015b). One microorganism was chosen from each group to represent drug sensitive strains (SA113), animal associated pathogens (S. pseudintermedius DSM21284) and drug-resistant human clinical organisms (MRSA ST528). It was decided that penicillin and chloramphenicol should be included for combinatorial analysis given previous reports of synergism between these antibiotics and nisin A (Lebel et al., 2013; Tong et al., 2014). Indeed, in our studies, a slight increase in lag time was evident when S. aureus SA113 was grown in the presence of sub-lethal concentrations of nisin (0.937μM; 3.0 μg/ml) and chloramphenicol (1.5 μg/ml) combined, compared to either compounds used alone (Figure 1A). However, a greatly extended lag time was evident in the case of the nisin derivative I4V + chloramphenicol and nisin V + chloramphenicol combinations. In contrast, when nisin and nisin derivatives were combined with vancomycin (0.5μg/ml), no enhanced antimicrobial effect was apparent since the combinations produced a shorter lag time than when vancomycin was used alone (Figure 1B). The nisin (0.937 μM; 3 μg/ml) and penicillin (0.005 μg/ml) and nisin derivative/penicillin combinations had little to no effect on the growth of SA113 at the concentrations used (Figure 1C).


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)

Growth curve analysis of Staphylococcus aureus SA113 in the presence of nisin A (A), nisin V (V), and nisin I4V (I4V) peptides (0.937 μM; 3.0 μg/ml) and in combination with 1.5 μg/ml chloramphenicol (Cm), 5.0 μg/ml vancomycin (Van) and 0.005 μg/ml penicillin (Pen). The means and standard deviations of three independent determinations are presented.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Growth curve analysis of Staphylococcus aureus SA113 in the presence of nisin A (A), nisin V (V), and nisin I4V (I4V) peptides (0.937 μM; 3.0 μg/ml) and in combination with 1.5 μg/ml chloramphenicol (Cm), 5.0 μg/ml vancomycin (Van) and 0.005 μg/ml penicillin (Pen). The means and standard deviations of three independent determinations are presented.
Mentions: Having established the MIC values for a range of antibiotics against the representative staphylococci, growth curves were performed in order to reveal more subtle features of the impact of sub-lethal concentrations of nisin A, nisin V, and nisin I4V alone, but also in combination with a selection of antibiotics on bacterial growth. The final concentration of nisin used for each organism was determined on the basis of MIC results obtained previously against these indicator strains (Field et al., 2010, 2015b). One microorganism was chosen from each group to represent drug sensitive strains (SA113), animal associated pathogens (S. pseudintermedius DSM21284) and drug-resistant human clinical organisms (MRSA ST528). It was decided that penicillin and chloramphenicol should be included for combinatorial analysis given previous reports of synergism between these antibiotics and nisin A (Lebel et al., 2013; Tong et al., 2014). Indeed, in our studies, a slight increase in lag time was evident when S. aureus SA113 was grown in the presence of sub-lethal concentrations of nisin (0.937μM; 3.0 μg/ml) and chloramphenicol (1.5 μg/ml) combined, compared to either compounds used alone (Figure 1A). However, a greatly extended lag time was evident in the case of the nisin derivative I4V + chloramphenicol and nisin V + chloramphenicol combinations. In contrast, when nisin and nisin derivatives were combined with vancomycin (0.5μg/ml), no enhanced antimicrobial effect was apparent since the combinations produced a shorter lag time than when vancomycin was used alone (Figure 1B). The nisin (0.937 μM; 3 μg/ml) and penicillin (0.005 μg/ml) and nisin derivative/penicillin combinations had little to no effect on the growth of SA113 at the concentrations used (Figure 1C).

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