In-Vitro Study the Antibacterial Activity of Bacteriocin against Stenotrophomonas Maltophilia and Evaluation its Synergism with some Antibiotics

Abstract

The core of the study is to screen the inhibitory effect of bacteriocin producing Lactobacillus acidophilus against isolated S. maltophilia and examine whether the combination of bacteriocin with antibiotics showed synergistic or antagonistic interaction. The majority of isolates were resistant to two antibiotics and the isolate coded S19 was resistant to the three antibiotics used, which is consider as multi-drugs resistant isolate and used for the synergy test. Initially, minimum inhibitory concentrations (MICs) of Ceftazidime (CAZ), Imipenem (IMP) and Minocycline (MIN) were determined using exponentially growing cultures of S. maltophilia. The MICs of antimicrobial were 64, 32 and 128μg/ml, respectively. When antimicrobial and bacteriocin combined in the checkerboard microtiter test, a synergistic effect was observed and the MICs decreased dramatically. All of the three antimicrobials with bacteiocin combinations showed synergy against the resistant S. maltophilia isolate (S19).A combination of Imipenem plus bacteiocin showed the highest syner gistic effect among the combinations. FIC index of a combination of Imipenem, Ceftazidime and Minocyclin with bacteriocin, were 0.249, 0.093 and 0.312 for S. malto philia isolate respectively. Antagonistic activity was not found in any of the combinations. In conclusion in the presence of bacteriocin, a lower Ceftazidime, Imipenem and Monocycline concentrations were needed to fully inhibit S. maltophilia .Checkerboard assay was appropriate method to calculate the MIC and combination testing of the bacteriocin and antibiotic as well as the fractional inhibitory concentration index (FICI) was applicable to aid in an interpretation of the combination testing results.

Synergistic antibacterial activity of silver nanoparticles biosynthesized by carbapenem-resistant Gram-negative bacilli

“…MIC of the clinical pathogens to antibacterial agents was determined by using broth microdilution method 25 . In this study, imipenem from ChemCruz-USA, ceftazidime, ceftriaxone, and cefepime from Awamedica-Iraq were used as antimicrobials.…”

“…The MICs of the antibiotics and Ag NP in combination were determined after 24 h of incubation at 37 °C, and the FIC was calculated as follows: Antibiotic A FIC = MIC of antibiotic A in combination/MIC of antibiotic A alone; antibiotic B FIC = MIC of antibiotic B in combination/the MIC of antibiotic B alone; the FICI = FIC of antibiotic A plus the FIC of antibiotic B. The FICI calculated was defined as follows: FICI ≤ 0.5 synergistic effect, 0.5 < FICI < 1 partial synergistic effect, FICI = 1 additive, 2 ≤ FICI < 4 indifferent, and 4 < FICI antagonism 25 , 27 , 28 .…”

“…The MICs of the antibiotics and Ag NP in combination were determined after 24 h of incubation at 37 °C, and the FIC was calculated as follows: Antibiotic A Vol:. ( 1234567890 The FICI calculated was defined as follows: FICI ≤ 0.5 synergistic effect, 0.5 < FICI < 1 partial synergistic effect, FICI = 1 additive, 2 ≤ FICI < 4 indifferent, and 4 < FICI antagonism 25,27,28 .…”

Broadening and Enhancing Bacteriocins Activities by Association with Bioactive Substances

“…Furthermore, Danesh et al [42] showed that haloduracin, a lantibiotic bacteriocin, associated with chloramphenicol displayed a wide spectrum of activity against pathogens such as Enterococcus faecalis, E. faecium, S. aureus and even against different strains of Streptococcus [42]. Recently, the combination of a bacteriocin, produced by Lactobacillus acidophilus, with ceftazidime, imipenem and minocycline antibiotics decreased the required minimal inhibitory concentrations (MICs) values of these antibiotics against a strain of Stenotrophomonas maltophila S19, which was previously shown to be resistant to these three aforementioned molecules [43]. Similarly, Al Atya et al [27] demonstrated the synergetic activities of two class IIb bacteriocins, enterocins DD28 and DD93, associated with kanamycin and erythromycin against a clinical strain of MRSA.…”