Fig. 1 The effect of N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide compound on biofilms formation by Haemophilus spp. on the basis of MBIC/MIC ratio Figure 2 shows the activity of N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide on the growth or biofilm formation by penicillinase-negative (S85Pen−) and penicillinase-positive (S86Pen+) H. parainfluenzae. In the case of penicillinase-positive isolate, the activity of the compound was significantly higher both on the growth and on the biofilm formation. Fig. 2 The effect of N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide compound

and ampicillin on the penicillinase-negative (filled diamond S85Pen−) and penicillinase-positive selleckchem (filled square S86Pen+) Haemophilus parainfluenzae planktonic or RAD001 price biofilm-forming cells (broth without bacteria: OD570 = 0.09–0.11) The in vitro cytotoxicity of the tested N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide compound was presented as percentage viability of vero cells used as an experimental model. According to the results shown in Table 2, after 48 h of incubation, no cytotoxic effect was observed up to 200 μg ml−1 concentration of the tested compound. The most widely used as a measurement of compound’s toxicity is the half maximal effective concentration (EC50), as the concentration of the GKT137831 research buy compound where

Unoprostone 50 % of its maximal effect is observed; in case of the tested compound EC50 = 278.8 μg ml−1. This means that this compound was not toxic to eukaryotic cells at concentrations exerting inhibitory effect against Haemophilus spp., including anti-biofilm activity. Table 2 The effect of N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide on vero cells line viability Compound concentration (μg ml−1)

Cell viability (in %) ± SD x 500 37.95 ± 7.7 200 82.15 ± 5.7 100 89 ± 6.6 50 93.55 ± 4.2 25 97.4 ± 1.7 12.5 98.05 ± 1.8 6.25 98.75 ± 2.0 3.15 100 ± 0.0 0 (control) 100 ± 0.0 Although the control of bacterial infections has been effective since the discovery of antimicrobial drugs, widespread drug resistance among bacteria has led to a search for new antibacterial agents. However, the finding of biofilm phenotype bacteria, showing usually intrinsic insensitivity to available drugs at standard dosing effective against planktonic cells, has created a necessity to pay more attention to targeted anti-biofilm agents. In this work, we have found that the N-ethyl-3-amino-5-oxo-4-phenyl-2,5-dihydro-1H-pyrazole-1-carbothioamide possessed good in vitro activity either against free-floating (planktonic) or biofilm-forming cells of Haemophilus spp. Haemophili rods, e.g., pathogenic H. influenzae or opportunistic H. parainfluenzae are found to be a part of proper microflora of the upper respiratory tract (Kilian, 2007; Murphy et al., 2007).