Register now or log in to join your professional community.
Hi all,
Pseudomonas infections are diseases caused by a bacterium from the genus Pseudomonas. The bacteria are found widely in the environment, such as in soil, water, and plants. They usually do not cause infection in healthy people. If an infection does occur in a healthy person, it is generally mild.
More severe infections occur in people who are already hospitalized with another illness or condition. Pseudomonades are one of the most common pathogens involved in hospital infections. A pathogen is a microorganism that causes disease. Infections acquired in a hospital are called nosocomial infections.
Pseudomonas aeruginosa is a convenient model organism with which to investigate the roles of oxygen limitation and anaerobiosis in protecting biofilm cells from antibiotics. This bacterium is commonly isolated from infections thought to involve biofilm formation, including those associated with burn wounds, keratitis, urinary catheters, otitis media, and pneumonia in patients with cystic fibrosis.
= It has recently been demonstrated that oxygen is locally depleted in the infected mucus of individuals with cystic fibrosis, underscoring the potential relevance of anaerobiosis in vivo. Oxygen gradients and local anaerobic conditions have also been measured in P. aeruginosa biofilms grown in vitro.
= In addition to slow growth, some of the other factors that have been implicated in P. aeruginosa biofilm protection from killing by antibiotics include specific genetic determinants phenotypic variation, the formation of specialized persister cells, quorum sensing, and overproduction of the matrix polysaccharide alginate.
= Several earlier studies have also investigated aspects of biofilm susceptibility as a function of growth rate. None of those studies, however, focused on the role of oxygen limitation in particular in the protection of P. aeruginosa biofilms
= There is a very limited literature that addresses the antibiotic sensitivity of P. aeruginosa under anaerobic conditions. It was found that the MICs and minimal bactericidal concentrations (MBCs) of Ciprofloxacin, Gentamicin, and Imipenem for P. aeruginosa in vitro under aerobic and anaerobic growth occurred in the Mueller-Hinton broth.
n Under anaerobic conditions, the MIC and MBC of Ciprofloxacin were slightly reduced;
n Those of Gentamicin were increased8-fold,
n While those of Imipenem were increased1.5- fold.
n It was suggested that Gentamicin may be less effective against P. aeruginosa under anaerobic conditions.
= In another study, it was found that anaerobic conditions are significantly reduced the efficacies of the following antibiotics tested against P. aeruginosa, which are Ciprofloxacin, Tobramycin, and Carbenicillin, Ceftazidime, Chloramphenicol, or Tetracycline.
- The protection from bacterial killing by Ciprofloxacin and Tobramycin afforded by an anaerobic environment was enhanced by the addition of nitrate, because nitrate supplementation under anaerobic conditions promoted the growth of the untreated control.
- This shows that antibiotic susceptibility is not strictly a function of the growth state but is determined by the specific nutrients present.
- The reduced efficacies of antibiotics for the killing of P. aeruginosa in the presence of nitrate and the absence of oxygen could help to explain the failure of antibiotic chemotherapy to control many infections associated with this microorganism.
Others recognized that the in vitro activity of Tobramycin in comparison to six other antimicrobial agents against Pseudomonas aeruginosa isolates collected from patients with cystic fibrosis during pretreatment with Tobramycin solution for inhalation.
n Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to Tobramycin than to Ceftazidime, Aztreonam, Amikacin, Ticarcillin, Gentamicin, or Ciprofloxacin.
n For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. The resistance mechanism is due to bacteria that are possessing aminoglycoside- modifying enzymes; the remaining was presumably resistant by an incompletely understood mechanism often referred to as “impermeability.
n Increased exposure to antibiotics raises concern regarding the potential for emergence of resistant P. aeruginosa isolates.
n Investigators have observed a correlation between resistance of P. aeruginosa and antibiotic administration.
= Pseudomonas infections are treated with antibiotics. Unfortunately, many hospital infections are becoming more difficult to treat. These bacteria have developed the ability to adapt and overcome antibiotics in their environment. This is called antibiotic resistance.
= The increase in antibiotic resistance has made treating infections much more challenging. Pseudomonas can often develop resistance to multiple types of antibiotics. It can even sometimes develop resistance during the course of treatment.
= It is important that a doctor select an effective antibiotic. A doctor may send a specimen from the patient to a laboratory first for testing in order to be more certain. The laboratory will then test the specimen to find out which antibiotic will work the best.
= Treatment may involve one or more of the following types of antibiotics:
Ceftazidime
Ciprofloxacin
Aminoglycosides
Cefepime
Aztreonam
Carbapenems
Ticarcillin
Ureidopenicillins
Notes:
- Mild skin infections may resolve on their own without treatment.
- Only a few antibiotics are effective against Pseudomonas, including Fluoroquinolones, Gentamicin and Imipenem, and even these antibiotics are not effective against all strains. The futility of treating Pseudomonas infections with antibiotics is most dramatically illustrated in cystic fibrosis patients, virtually all of whom eventually become infected with a strain that is so resistant that it cannot be treated.
- Dual antibiotic treatment (usually with a Beta-lactam and an aminoglycoside) is now standard for the intravenous treatment of CF lung exacerbations, and combination therapy is increasingly utilized for out-of-hospital maintenance. However, selection of effective combination therapy can present many challenges.
thanks,
Lubna
Pseudomonas has more than one type here i mention fore the antibiotic that is use for P. aeruginosa
Because P. aeruginosa is commonly resistant to antibiotics, infections are usually treated with two antibiotics at once. Pseudomonas infections may be treated with combinations of ceftazidime (Ceftaz, Fortraz, Tazicef), ciprofloxacin (Cipro), imipenem (Primaxin), gentamicin (Garamycin), tobramycin (Nebcin), ticarcillin-clavulanate (Timentin), or piper-acillin-tazobactam (Zosyn). Most antibiotics are administered intravenously or orally for two to six weeks. Treatment of an eye infection requires local application of antibiotic drops
Most isolates were sensitive to ofloxacin (77.6%), cefuroxime (76.6%), ciprofloxacin (75.3%), perfloxacin (66.0%), streptomycin (64.0%) and gentamicin (59.8%). Appreciable resistance to ceftazidime (50.7%) and increasing resistance to gentamicin (40.2%) than is previously known, were recorded
Ciprofloxacin
Chlorophenicol is one of the best antibiotic that can act against Pseudomnas whether isolated from any samples
well i was unfortunate to isolate pseudomonas in the laboratory and the routine sensitive discs i used proved to all be resistant to the isolate and upon my search i came across combination therapy ,which prompt me to make varying strength of anti sensitivity disc with combined antibiotics and just like magic, i got lots of zone of inhibition with combined ciprofloxacin and meroneme.
so in conclusion ,i think combination therapy is the best for inhibiting or stoping the growth of pseudomonas as demonstrated invitro in my place of work
