Abstract
Emergence of multiple drug resistant strains of pathogenic bacteria calls for new initiatives to combat infectious diseases. Gold nanoparticles (AuNPs), because of their non-toxic nature and size/shape dependent optical properties, offer interesting possibility. Here we report the antibacterial efficacy of AuNPs of different size and shape (AuNS10, AuNS100 and AuNR10; the number indicating the diameter in nm; S stands for sphere and R for rod) against the classical (O395) and El Tor (N16961) biotypes of Vibrio cholerae, the etiological agent responsible for cholera. Growth kinetics was monitored by measuring optical density at different time intervals and fitted by non-linear regression of modified Buchanan model. Sigmoidal growth curve for VcO395 indicated the existence of single phenotype population and was affected by AuNR10 only, implying the importance of morphology of AuNP. Growth of VcN16961 was affected by all three AuNPs indicating the vulnerability of El Tor biotype. Interestingly, VcN16961 exhibited the occurrence of two phenotypic subpopulations – one with shorter (vulnerable Type 1) and the other with extended (tolerant Type 2) lag phase. Various assays were conducted to probe the impact of AuNPs on bacterial cells. Apart from AuNR10, antimicrobial efficacy of AuNS10 was better compared to AuNS100.
Highlights
The emergence of multiple drug resistant (MDR) strains of pathogenic bacteria is a potential health threat[1]
The growth kinetics of both biotypes of V. cholerae was monitored by measuring OD at 595 nm at different time intervals
The emergence of MDR strains has added a new dimension in the fight against pathogenic organisms, bolstering our search for developing alternatives to antibiotics[33]
Summary
The emergence of multiple drug resistant (MDR) strains of pathogenic bacteria is a potential health threat[1]. The growth kinetics of VcN16961 was found to be affected by AuNP of different size (AuNS10 and AuNS100) and shape (AuNR10), indicating the vulnerability of the El Tor biotype towards AuNP over the classical one. The maximum growth rate (or the maximum slopes of OD595 of the two subpopulations with time) s1 and s2 for two subpopulations of VcN16961 in presence of AuNS10 as obtained from modified Buchanan model can be represented by eqns 6 and 7 as s1 = 0.00353e−0.0271[AuNS10]
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