Bensal HP (BHP-410), a Novel Antimicrobial Agent with Activity against MRSA, VRE, Gram-negative MDROs, Yeasts, and Dermatophytic Fungi K. S. Thomson1, G. K. Thomson2, J. Biehle3, A. Deeb1, J. Crawford1, R. Herrera1, I. Robledo4 and G. Vázquez4 TM 1. Bensal HP has an extremely broad spectrum of activity that is not compromised by mechanisms of antibiotic resistance occurring in contemporary multidrug resistant bacteria. 2. All gram-positive and gram-negative bacteria, yeasts, and filamentous fungi in this study were susceptible to the clinically used concentration of Bensal HP (i.e. inhibited by undiluted ointment). 3. No resistance to Bensal HP was detected. 4. Bensal HP was rapidly bactericidal in time-kill studies with an isolate of Pseudomonas aeruginosa and an isolate of MRSA. 5. Further study is warranted to investigate its full clinical utility. 1 Creighton University, Omaha, NE, 2 University of Louisville Hospital, Louisville, KY, 3 Alegent Creighton Hospital, Omaha, NE, 4 University of Puerto Rico, San Juan, Puerto Rico References 1. Moland, E. S., N. D. Hanson, J. A. Black, A. Hossain, W. Song, and K. S. Thomson. 2006. Prevalence of newer β- lactamases in gram-negative clinical isolates collected in the United States from 2001 to 2 0 0 2 . J C l i n M i c r o b i o l 44:3318-24. 2. Barry, A. L. 1991. Procedures and Theoretical Considerations f o r Te s t i n g A n t i m i c r o b i a l Agents in Agar Media, p. 1-16. In V. Lorian (ed.), Antibiotics in Laboratory Medicine, 3rd ed. Williams & Wilkins, Baltimore. 3. Clinical and Laboratory Standards Institute. 2013. Performance standards for antimicrobial susceptibility testing; twenty-third infor- mational supplement M100- S23. Clinical and Laboratory Standards Institute, Wayne, PA. Background Background: Increasing multidrug resistance and a dwindling antibiotic pipeline have created a major global health crisis. Little is known about the activity of topical agents against multidrug resistant organisms (MDROs) or about their therapeutic or infection control relevance in meeting this challenge. With this in mind, a study was designed to assess the activity of a novel topical antimicrobial BHP-410 containing salicylic acid, benzoic acid and QRB-7 (oak bark extract) against a broad range of MDRO's including MRSA, VRE, ESBL and carbapenemase-producing isolates. In addition its activity against selected isolates of Mycobacterium fortuitum, Nocardia brasiliensis, yeasts and filamentous fungi was also assessed. Materials and Methods: Activity against 181 isolates comprising 12 bacterial species (5 gram- negative, 7 gram-positive), 3 yeast species, and 3 dermatophyte species was assessed. The 129 bacterial isolates included well characterized non-MDRO and MDRO isolates of Enterobacteriaceae P. aeruginosa, A. baumannii, S. aureus, and Enterococcus faecalis a n d r o u t i n e c l i n i c a l i s o l a t e s o f G r o u p A s t r e p t o c o c c i , Propionibacterium acnes, M. fortuitum and N. brasiliensis. Twenty one isolates of Candida albicans, C. glabrata, Cryptococcus neoformans and 30 isolates of Trichophyton rubrum, T. tonsurans, and T. mentagrophytes were also tested. Susceptibility to BHP-410 was determined by the cylinder diffusion and CLSI agar dilution methods. Bactericidal activity was assessed by time-kill methodology. Results: In cylinder diffusion tests, all bacterial and fungal isolates were inhibited by BHP-410 and no resistance was detected. There was no apparent reduction in inhibition zone when comparing MDRO-isolates to non-MDRO (wild type) isolates. In MIC tests non-MDRO and MDRO isolates were equally susceptible with all gram-positive isolates (including MRSA) inhibited by an 80-fold dilution of BHP-410. Gram-negative isolates were all susceptible within a range of 40 to 80-fold dilutions. BHP-410 was rapidly bactericidal against P. aeruginosa and MRSA. Conclusion: BHP-410 has an extremely broad spectrum of antimicrobial activity and is unaffected by the resistance mechanisms of MDROs. Further study is warranted to investigate its full clinical utility. The combination of increasing multidrug resistance and a dwindling antibiotic pipeline has created a major global health crisis in which there are few or no effective agents to treat bacterial infections. Little is known about the activity of topical agents against multidrug resistant organisms (MDROs) or about the therapeutic or infection control potential of topical agents in meeting this challenge. Bensal HP (BHP-410) is a broad spectrum topical antimicrobial agent containing salicylic acid (30 mg/gm), benzoic acid (60 mg/gm), QRB-7 (oak bark extract, 30 mg/gm) and vehicle polyethylene glycol 400 and polyethylene glycol 3350. The current study was designed to assess its activity against a broad range of contemporary pathogens including MDROs such as MRSA, vancomycin-resistant Enterococcus (VRE), MDR producers of AmpC, extended spectrum β- lactamase (ESBL) and carbapenemase β -lactamases, Mycobacterium fortuitum, Nocardia brasiliensis, yeasts and filamentous fungi. Abstract Materials & Methods Test Agent: Bensal HP PDUNHWHG�E\�(3,�+HDOWK (&KDUOHVWRQ�6&) Organisms: In vitro activity was investigated against 184 bacterial and fungal isolates from the culture collections of Creighton University, Omaha, NE, the Alegent Creighton Hospital Microbiology Laboratory, Omaha, NE, and the University of Louisville Hospital Microbiology Lab, Louisville, KY. The isolates were from U.S. and international sources and included well characterized non-MDRO and MDRO isolates of Enterobacteriaceae (n=40), Pseudomonas aeruginosa (n=11), Acinetobacter baumannii (n=13), Staphylococcus aureus (n=23) including MRSA and methicillin-susceptible S. aureus (MSSA), and Enterococcus faecalis (n=11) including VRE. Also tested were routine clinical isolates of Group A Streptococcus (S. pyogenes, n=12), Propionibacterium acnes (n=1), Mycobacterium fortuitum (n=10) and Nocardia brasiliensis (n=10). The fungal isolates included Candida albicans (n=10), C. glabrata (n=10), Cryptococcus neoformans (n=1), Trichophyton rubrum (n=12), T. tonsurans (n=10), and T. mentagrophytes (n=10). The MDROs were previously characterized for resistance mechanisms by phenotypic, biochemical and molecular methods (1) and included isolates producing the ESBLs TEM-52, SHV ESBLs, OXA-45, CTX-M-1, CTX- M-9, CTX-M-12, CTX-M-14, CTX-M-15, CTX-M-17, CTX-M-18, and CTX-M-19, chromosomal and plasmid-mediated AmpC β-lactamases that included FOX-like and CMY-2 enzymes, and carbapenemases of the IMP, VIM, KPC, and NDM families. Especially challenging MDROs included carbapenemase-producing isolates of P. aeruginosa and A. baumannii and P. aeruginosa isolates with upregulated MexAB, MexEF, and MexXY efflux pumps, and down-regulation of the OprD porin. Investigations Susceptibility was determined by the cylinder diffusion (2) and CLSI agar dilution (3) methods. Examples of cylinder diffusion tests are shown in Figure 1. Bactericidal activity was assessed by time-kill methodology following exposure of P. aeruginosa ATCC 27853 and MRSA SA179 to concentrations of 1x and 4x the MIC. Results All isolates, bacterial and fungal, were inhibited by Bensal HP. No resistance was detected. No MDRO isolates exhibited cross resistance to Bensal HP. That is, susceptibility was unaffected by the innate or acquired resistance mechanisms of the isolates. Zone diameters were generally larger for gram-positive bacteria and filamentous fungi than for gram-negative bacteria (Table 1). Some MDROs had larger inhibition zones than their wild type counterparts. Representative isolates exhibiting this trend are shown in Table 2. In MIC tests with 73 selected isolates that included both MDROs and non-MDROs in each species tested, all gram-positive isolates were inhibited by an 80-fold dilution of Bensal HP (MIC = 0.375/ 0.75/ 0.375 mg/gm of salicylic acid/benzoic acid/QRB-7 respectively) and the gram-negative isolates were all susceptible to a 40-fold dilution (MIC = 0.75/ 1.5/ 0.75 mg/gm of salicylic acid/benzoic acid/QRB-7 respectively), with most gram-negatives being susceptible to an 80-fold dilution (0.375/ 0.75/ 0.375 mg/gm). In time-kill tests, BHP-410 was rapidly bactericidal against P. aeruginosa ATCC 27853 and MRSA SA179 at 4x the MIC (1:20 dilution) with no regrowth occurring in the 24 hour incubation period (Figures 2 and 3). Results Conclusions Figure 1: Representative Cylinder Diffusion Tests Figure 3: Time-Kill Curves – Pseudomonas aeruginosa Figure 2: Time-Kill Curves - MRSA Table 1: Summary of Cylinder Diffusion Tests Table 2: Representative Examples of Wild Type Strains with Smaller Inhibition Zones than MDROs Methicillin-Resistant Staph. aureus Pseudomonas aeruginosa Escherichia coli Common Bacterial Isolates Common Yeast & Fungal Isolates Candida albicans Trichophyton tonsurans Trichophyton rubrum Trichophyton mentagrophytes Clinical Resistance Challenges Select Isolates Enterococcus faecalis (VRE) Klebsiella pneumoniae (MDRO) Acinetobacter baumannii (KPC +) Candida glabrata FC17PosterEPIHealthThomsonBensalHP.pdf