Antimicrobial activity of mul-1867, a novel antimicrobial compound, against multidrug-resistant Pseudomonas aeruginosa.

BACKGROUND: There is an urgent need for new antimicrobial compounds to treat various lung infections caused by multidrug-resistant Pseudomonas aeruginosa (MDR-PA). METHODS: We studied the potency of Mul-1867 against MDR-PA isolates from patients with cystic fibrosis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia. The minimal inhibitory concentrations (MICs) and minimum biofilm eliminating concentrations (MBECs), defined as the concentrations of drug that kill 50 % (MBEC50), 90 % (MBEC90), and 100 % (MBEC100) of the bacteria in preformed biofilms, were determined by using the broth macrodilution method. RESULTS: Mul-1867 exhibited significant activity against MDR-PA and susceptible control strains, with MICs ranging from 1.0 to 8.0 µg/mL. Mul-1867 also possesses anti-biofilm activity against mucoid and non-mucoid 24-h-old MDR-PA biofilms. The MBEC50 value was equal to onefold the MIC. The MBEC90 value ranged from two to fourfold the MIC. Moreover, Mul-1867 completely eradicated mature biofilms at the concentrations tested, with MBEC100 values ranging between 16- and 32-fold the MIC. Mul-1867 was non-toxic to Madin-Darby canine kidney (MDCK) cells at concentrations up to 256 µg/mL. CONCLUSION: Overall, these data indicate that Mul-1867 is a promising locally acting antimicrobial for the treatment and prevention of P. aeruginosa infections.

Antimicrobial susceptibility differences among mucoid and non-mucoid Pseudomonas aeruginosa isolates.

Pseudomonas aeruginosa is one of the most important opportunistic bacteria, causing a wide variety of infections particularly in immunocompromised patients. The extracellular glycocalyx is produced in copious amounts by mucoid strains of P. aeruginosa. Mucoid and non-mucoid P. aeruginosa strains show some differences in their antimicrobial susceptibility pattern. The aim of this study was to investigate the frequency of mucoid and non-mucoid types and their antimicrobial susceptibility patterns isolated from Milad and Mostafa Khomeini Hospital in Tehran, Iran. One hundred P. aeruginosa isolates were collected which all were confirmed by conventional biochemical tests and PCR assay using specific primers for oprI and oprL lipoproteins. Mucoid and non-mucoid types of isolates were determined by culturing isolates on BHI agar containing Congo red and Muir mordant staining method. The susceptibility pattern of isolates against 23 different antibiotics was assessed using MIC sensititre susceptibility plates. Fifty of 100 of isolates were mucoid type, of which 14 isolates were from Mostafa Khomeini Hospital. Frequency of mucoid type of P. aeruginosa in Mostafa Khomeini hospital (70%) was higher than that seen in Milad hospital (45%). The statistical analysis of MICs results showed significant differences in antimicrobial resistance among mucoid and non-mucoid types (non mucoid strains showed more resistance against tested antibiotics). This may be due to the tendency of some antibiotics to attach to extracellular glycocalyx of mucoid strains.

Comparison of drug resistance between mucoid and non-mucoid Pseudomonas aeruginosa / 中华临床感染病杂志

Objective To compare the drug resistance of mucoid Pseudomonas aeFagillosa with that of non-mucoid.Methods All specimens isolated and cultured from patients were identified and the antibiotic sensitivity was tested by automatic microorganism analyzer VITEK-32,GNI+,GNS-448,E-teat and K-B.Results Drug resistant rates of mucoid Pseudomonas aeruginosa to imipenem.levofloxacin.meropenem,cefepime,cefoperazone/sulbactam,amikacin,gentamicin,piperacillin.tazobactam,ceftazidime and cefotaxime were 5.3%, 16.1%, 5.6%, 20.6%, 1.1%, 10.5%,26.9%,5.3%.31.5% and 60.2%,respectively.The drug resistant rates of mucoid Pseudomonas aeruginosa were lower than those of non-mucoid except to ceftazidime.Conclusion Compared with non-mucoid Pseudomonas aeruginosa,antibiotic resistance of mucoid Pseudomonas aeruginosa is weaker in vitro.