We investigated the antimicrobial activity of four polymyxin B components, B1, B2, B3, and isoleucine (Ile)-B1, individually and in combination. B3 was the most active agent against all organisms tested except Acinetobacter baumannii, for which Ile-B1 was most active. One combination met the criteria for synergy, B3 plus Ile-B1. No combinations exhibited antagonism. The dominant components of p...

The acquisition of blaNDM-1 gene by Gram negative bacteria has emerged as critical threat to human health as these organisms display high resistance to available antibiotics. The presence of this gene has been observed in both clinical as well as environmental settings. The present study was carried out to evaluate the prevalence of blaNDM-1 containing microorganisms in water sources. A total o...

This work reports the identification of the first case of a KΡC-2-producing Pseudomonas putida isolate (PP36) in Brazil. The PP36 isolate was resistant to all the antimicrobials tested except polymyxin B. In addition to the discovered bla(KPC-2) gene, genetic analysis showed the presence of a class 1 integron containing the dhfrXVb gene and the new allele arr-6, which codes for resistance to ri...

Polymyxin B is increasingly used as a treatment of last resort for multidrug-resistant Gram-negative infections. Despite being available as a mixture of several structurally related analogues, the properties are commonly reported as an aggregate of the individual components. We compared the pharmacokinetics of individual polymyxin B components in an animal model and in humans. There were no con...

A commercially available antibiotic mixture effectively decreased overgrowth of Sabouraud medium by gram-negative flora frequently found in the sputum of hospitalized patients.

Acinetobacter baumannii has emerged as a troublesome nosocomial pathogen worldwide. We report here the draft genome sequence of polymyxin B-resistant sequence type 195 (ST195) A. baumannii strain GU71, isolated from a tertiary care hospital in the city of Guwahati, Assam, India.

A polymyxin B-resistant strain of Proteus mirabilis was converted into L forms and spheroplasts in the presence of penicillin G. This treatment caused a 400-fold increase in polymyxin B susceptibility. The acquired susceptibility was in the range of the natural susceptibility reported for susceptible gram-negative bacteria ( approximately 1 mug/ml). The high susceptibility to polymyxin B was lo...