Oligopeptide-binding protein (OppA) is the periplasmic component of the major oligopeptide transport system of enteric bacteria. Genetic and biochemical evidence suggests that OppA plays a role in the uptake of aminoglycoside antibiotics in Escherichia coli K-12. Forty-six (82%) of 56 aminoglycoside-resistant mutants of E. coli K-12 selected in vitro had reduced or undetectable OppA levels, as compared with their parent strain. Moreover, nine (36%) of 25 aminoglycoside-resistant clinical isolates of E. coli expressed reduced or undetectable levels of OppA. No decrease in OppA expression was observed among aminoglycoside-sensitive E. coli strains from patients. Twenty-three (42%) of 56 aminoglycoside-resistant mutants of E. coli K-12 and six (24%) of 25 clinical isolates also were de®cient for expression of ornithine or arginine decarboxylases, or both, and these de®ciencies might negatively affect OppA expression by reducing polyamine synthesis. These results support the view that reduced OppA expression is associated with aminoglycoside resistance in E. coli strains.

The role of intracellular free polyamine (putrescine and spermidine)

Food and beverages products sold in street are a growing global trend. In natura products have recognized nutritional and functional proprieties; on the other hand, its sanitary aspects are a crucial concern because of the risk of food‐borne diseases, due to the lack of minimal structure at manipulating the foods.ObjectiveTo evaluate the microbiological quality of in natura beverages: juice, coffee and sugar cane produced and sold in streets.MethodsIt has been collected four samples of each product (orange juice, coffee and sugar cane) in the streets near the subway downtown Sao Paulo, Brazil. It has been immediately analyzed for microbial burden, fungi and yeasts, fecal and thermotolerant coliforms, and Enterobacteriaceae Salmonella and Shigella.ResultsTotal coliforms have been shown in all samples, in contrast to fecal ones. Staphylococcus aureus have been observed in sugar cane. Streptococci beta‐haemolytic were absence in all samples, but alpha‐haemolytic were in sugar cane and in orange juice. In all cases the count of aerobic mesophilic was bigger then 106.ConclusionThese results indicate the unsatisfactory microbiological quality for human intake, that denotes the lack of basic knowledge about manipulation of food and the relevant application of that.