Synergistic activity of 1-(1-naphthylmethyl)-piperazine with ciprofloxacin against clinically resistant Staphylococcus aureus, as determined by different methods

Abstract

Aims: To evaluate the interaction of 1-(1-naphthylmethyl)-piperazine (NMP) and ciprofloxacin (CPFX) in vitro against fluoroquinolone (FQ)-resistant clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). Methods and Results: The in vitro interaction of NMP and CPFX in 12 FQresistant clinical isolates of MRSA was assessed using a checkerboard microdilution method. In the study, a synergistic antimicrobial effect between NMP and CPFX was observed in all 12 FQ-resistant strains tested, as determined by the fractional inhibitory concentration index (FICI), and in 10 strains using DE models. No antagonistic activity was observed in any of the strains tested. These positive interactions were also confirmed using the time-killing test and agar diffusion assay for the selected strain, MRSA 1862; synergistic activity was observed when NMP was combined with the first-line antimicrobial agent CPFX against Staph. aureus. Conclusions: Synergistic activity between NMP and CPFX against clinical isolates of FQ-resistant Staph. aureus was observed in vitro. Significance and Impact of the Study: This report might provide alternative methods to reduce the resistance of Staph. aureus to CPFX.

Coriander essential oil and linalool - interactions with antibiotics against Gram-positive and Gram-negative bacteria

“…The ∑ SYN and ∑ ANT were calculated only for the statistically significant synergism and antagonism separately by summing up the ΔE values (Li et al . ; Segatore et al . ).…”

“…Antagonism is represented by the points of the response surface (DE) below zero (statistical significance if DE < 0 and 95% confidence interval overlaps 0). The ∑SYN and ∑ANT were calculated only for the statistically significant synergism and antagonism separately by summing up the DE values (Li et al 2011;Segatore et al 2012).…”

Contribution of target alteration, protection and efflux pump in achieving high ciprofloxacin resistance in Enterobacteriaceae

“…Mutations within the regulatory proteins were studied after sequencing by bioinformatics analysis of the deduced amino acid sequences (Akter et al 2012). PCR positive isolates were subjected to MIC CIP determination by microdilution broth checkerboard technique in the presence and absence of an efflux pump inhibitor 1-(1-naphthylmethyl) piperazine (NMP) (SIGMA-ALDRICH, USA) in 96-well microtiter plates (Li et al 2011). The checkerboard plates were inoculated with 10 5 –10 6  CFU/mL each of bacterial culture and the final concentrations of NMP and CIP ranged from 512–4 µg/mL and 512–2 µg/mL respectively and bacterial growth was monitored after 24–36 h. The OD 600 nm of the plate was taken and the background OD was subtracted from the OD of each well.…”

“…The checkerboard plates were inoculated with 10 5 –10 6  CFU/mL each of bacterial culture and the final concentrations of NMP and CIP ranged from 512–4 µg/mL and 512–2 µg/mL respectively and bacterial growth was monitored after 24–36 h. The OD 600 nm of the plate was taken and the background OD was subtracted from the OD of each well. The interaction between the antibiotic and the inhibitor was interpreted on the basis of fractional inhibitory concentration (FIC) index where FIC indices of <0.5, 0.5 to <4.0 and >4.0 usually refer to synergism, additive and antagonism respectively (Braga et al 2005; Li et al 2011; Odds 2003). …”

“…Among these mechanisms, target alteration has been reported to be responsible for a high level of resistance to CIP whereas efflux pump and Qnr protein mediated mechanisms attributed to a low level of resistance (Jacoby 2005; Strahilevitz et al 2009). Most of the previous studies focused on either single mechanism in many organisms or all three mechanisms in a single type (Kuo et al 2009; Li et al 2011; Lindgren et al 2003; Tran and Jacoby 2002; Tran et al 2005; Vanni et al 2014). However, high resistance to this drug is emerging swiftly among Enterobacteriaceae leaving this drug ineffective against many infections and increasing the cost of treatment.…”