Calcium-dependent antibiotic

Hojati, Z., Milne, C., Harvey B. et al. (2002) Structure, biosynthetic origin, and engineered biosynthesis of calcium-dependent antibiotics from Streptomyces coelicolor. Chemistry Biology, 9, 1175. 

Jung D, Rozek A, Okon M, Hancock RE. (2004) Structural transitions as determinants of the action of the calcium-dependent antibiotic daptomycin. Chem Biol 11 949-957. 

Ryding NJ, Anderson TB, Champness WC (2002) Regulation of the Streptomyces coelicolor calcium-dependent antibiotic by absA, encoding a cluster-linked two-component system. J Baderiol 184 794-805... 

It is an immunosuppressant macrolide antibiotic produced by Streptomyces tsukubaensis. Like cyclosporine, tacrolimus binds to a cytoplasmic immunophylin and the complex inhibits the activity of the calcium dependent phosphatase known as calcineurin. This in turn, inhibits the translocation of the transcription factor NF-AT into the cell nucleus, blocking the initiation of NF-AT dependent T-cell responses. It is indicated in atopic dermatitis. 

Lakey JH. Ptak M. Fluorescence indicates a calcium-dependent interaction between tipopep-tidt antibiotic LY146032 and phospholipid membranes. Biochem 1988 27 4639-4645. 

A 59-year-old woman presents to an urgent care clinic with a 4-day history of frequent and painful urination. She has had fevers, chills, and flank pain for the last 2 days. Her physician advised her to immediately come to the clinic for evaluation. In the clinic she is febrile (38.5°C [101.3°F]) but otherwise stable and states she is not experiencing any nausea or vomiting. Her urine dipstick test is positive for leukocyte esterase. Urinalysis and urine culture are also ordered. Her past medical history is significant for three urinary tract infections in the past year. Each of these episodes was uncomplicated, treated with trimethoprim-sulfamethoxazole, and promptly resolved. She also has osteoporosis for which she takes a daily calcium supplement. The decision is made to treat her with oral antibiotics for a complicated urinary tract infection with close follow-up. Given her history what would be a reasonable empiric antibiotic choice Depending on the antibiotic choice are there potential drug interactions she should be counseled on ... 

The antimicrobial activity of this class of antibiotics depends on the presence of calcium ions. This group of antibiotics contains the clinically important antimicrobial agent, daptomycin (cubicin). 

Among the enniatin antibiotics, beauvericin is the one characterized in greater detail. This carrier is most interesting with respect to an anion-dependence of its transport properties Moreover, in contrast to valinomycin, it is capable of com-plexing alkaline earth as well as alkali metal ions . A study of the effects of beauvericin on the conductivity of artificial lipid membranes in the presence of both mono- and divalent cations revealed a second-order relationship between conductance and antibiotic concentration Finally, Prince, Crofts, and Steinrauf detected an apparent charge of plus one for calcium in the beauvericin-mediated transport across bacterial chromatophore membranes... 

A retrospective case-control study of the effect of ceftriaxone on the urinary concentration of calcium included 103 patients who were treated for bacterial pneumonia. The patients were divided into groups depending on which antibiotic they received. Calcium and creatinine levels in serum and urine were collected before and after treatment, and the urinary calcium to creatinine ratios (uCa/Cr mg/mg) were calculated. There was a significant difference when comparing the uCa/Cr ratio in the ceftriaxone group to that of the amoxicillin group after treatment. These results showed that ceftriaxone increases the urinary excretion of calcium, and therefore may increase the risk of urolithiasis. The authors suggest that levels of uCa/Cr should be measured in patients in order to prevent this [70 ]. 

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