Pseudomonas antibiotic sensitivity

Ayres HM, Furr JR, Russell AD. Effect of permeabilizers on antibiotic sensitivity of Pseudomonas aeruginosa. Lett Appl Microbiol 1999 28(1) 13-16. 

It is formed by acylases that cleave off the side chain of the penicillins, and can also be obtained by the selective chemical cleavage of the amide, leaving the lactam intact. After this, 6-APA can be easily acylated by any carboxylic acid, and this has yielded literally thousands of semisynthetic penicillins in the past 30 years, many showing improved stability and activity. Some of them are lactamase resistant (methicillin (9.41), oxacillin (9.42) and its halogenated derivatives), whereas others are broad-spectrum antibiotics, like the orally active ampicillin (9.43), which also inhibits Gramnegative bacteria but is sensitive to lactamase. Carbenicillin (9.44) is particularly active against Pseudomonas and Proteus infections, which are unaffected by natural penicillins. Piperacillin (9.45), a broad-spectrum compound, is spectacularly active against Pseudomonas. 

High sensitivity of Staphylococcus spp. to different antibiotics can be explained by its relatively low presence in the general population. This microorganism has been found only in 4.5% of population and its resistance did not develop. Other agents with higher presence have high antibiotic resistance. The mean resistance of Klebsiella pneumoniae to different antibiotics was 74.8 22.5% Pseudomonas aeruginosa - 68.4 26.7% Acinetobacter spp. - 77.9 21.8% and Staphylococcus aureus - 72.0 20.1%. 

Some plant pathogenic bacteria and their phytotoxins have been screened in bioassays that monitor the effects of their toxins (antibiotic and phytotoxic) on other sensitive bacteria. For example, several fluorescent Pseudomonas syringae pvs. produce extracellular phytotoxins.76,106,116 Tabtoxin is produced by P. syringae pv. tabaci and pv. coronafacines, and this natural product inhibits glutamine synthetase.34,46,116 Phaseolotoxin, produced by P. syringae pv. phaseolicola... 

Contact dermatitis due to arbekacin has been reported (122). The risk of sensitization by topically administered gentamicin seems to be smaller. Nevertheless, and in order to avoid resistance, topical use should be restricted to life-endangering thermal burns and to severe skin infections in which strains of Pseudomonas resistant to other antibiotics are involved. 

Many in vitro studies have firmly established a synergism between sulbactam and various P-lactam antibiotics including piperacillin, amdinocillin, ampicillin, and penicillin G. These studies included bacterial strains resistant to ampicillin or penicillin G alone, which became sensitive upon addition of sulbactam. Carbenicillin-resistant Pseudomonas, however, was not potentiated. 

Tateda, K., Hirakata, Y., Furuya, N., Ohno, A., and Yamaguchi, K. (1993). Effects of sub-MlCs of erythromycin and other macrolide antibiotics on serum sensitivity of Pseudomonas aeruginosa. Antimicrob. Agents. Chemother. 37, 675-680. 

Infections of the skin, mucous membranes, eye, and ear due to polymyxin B—sensitive microorganisms respond to local application of the antibiotic in solution or ointment. External otitis, frequently due to Pseudomonas, may be cured by the topical use of the drug. R aeruginosa is a common cause of infection of comeal ulcers local application or subconjunctival injection of polymyxin B often is curative. 

The first report of a specific screening technique designed to search for p-lactam antibiotic-producing cultures was described by Kitano et al. (1975). A mutant of Pseudomonas aeruginosa highly and specifically sensitive to p-lactam antibiotics was isolated. A similar mutant strain of Escherichia coli highly sensitive to p-lactam antibiotics was used in the detection of nocardicins (Aoki et al., 1976). 

Septicaemia from prolonged intravenous infusions is a well-known complication and it has therefore been generally accepted that infusion sets should not be used longer than 24 hours (maximum 48 hours). Intravenous systems used for over 48 hours have been shown to increase the risk of contamination by 15% as compared with systems in use for less than 48 hours (3%) (12 ). Four cases of septicaemia in children receiving Lv. infusion (5% dextrose-saline) have been observed, all caused by Pseudomonas cepacia contamination (13 ). The isolated strains were sensitive to sulfonamides, co-trimoxazole and chloramphenicol,- but resistant to gentamicin, polymyxin B and other antibiotics. One patient died after a long and comphcated post-operative period. The other 3 recovered after chloramphenicol therapy within 2 weeks. 

---