Evaluation of the E test for the assessment of synergy of antibiotic combinations against multiresistant Pseudomonas aeruginosa isolates from cystic fibrosis patients

The determination of synergistic effects of antimicrobial drug combinations can lead to improved therapeutic options in the antibiotic treatment of cystic fibrosis patients who are chronically infected with multiresistant Pseudomonas aeruginosa isolates. The aim of this study was to evaluate the performance of the E test versus the standard agar dilution checkerboard susceptibility test in the assessment of synergy and, in addition, to determine the activity of two antimicrobial combinations against 163 multiresistant P. aeruginosa isolates from cystic fibrosis patients. The agreement between the checkerboard method and the E test was excellent (>90%) for nonmucoid as well as mucoid isolates from cystic fibrosis patients. The rate of synergy was higher for the antibiotic combination of ceftazidime and tobramycin (28.8% of the cystic fibrosis strains) than for the combination of meropenem and tobramycin (19.0%). However, the probability of synergy for the second antibiotic combination increased significantly when the synergy of the first antibiotic combination had already been demonstrated (Fischer’s exact test, p=0.049). The results show that the E test is a valuable and practical method for routine microbiological diagnostics and can aid in the selection of improved antibiotic options in the treatment of cystic fibrosis patients chronically infected with P. aeruginosa.     

Myogenic and neurogenic regulation of myosin gene expression in cat jaw-closing muscles regenerating in fast and slow limb muscle beds

Summary Immunocytochemical techniques were used to study changes in myosin gene expression during the regeneration of the cat posterior temporalis muscle transplanted into the bed of either the fast extensor digitorum longus (EDL) or the slow soleus muscle. Strips of the posterior temporalis, a homogeneously superfast muscle, were treated with Marcaine and then transplanted into limb muscle beds which had been completely cleared of host muscle fibres. The regenerates were examined 6 to 224 days after surgery. Early regenerates in both muscle beds reacted with antibodies against the heavy chain of foetal, slow and superfast myosins, but not with antibodies against fast myosin. In the long-term, regenerates innervated by the EDL nerve expressed only superfast myosin whereas in the regenerates innervated by the soleus nerve most fibres expressed only slow myosin and only a few fibres reacted exclusively with the anti-superfast myosin antibody even after 210 days. In contrast, EDL and soleus muscles regenerating in their own beds expressed foetal, slow and fast myosin, but did not express superfast myosin. The isometric contraction times of the various types of regenerates reflected the types of myosin synthesized. It is concluded that jaw and limb muscle cells exist as two distinct allotypes, each having a distinct repertoire for the expression of adult isomyosins, and that within that repertoire isomyosin gene expression can be modulated by the nerve. Thus, myosin gene expression in skeletal muscle fibres is regulated by both myogenic and neurogenic mechanisms.     

Adverse reactions to an absorbable shoulder fixation device

Bioabsorbable implants have been advocated for use in repair of a torn glenoid labrum to correct shoulder instability. These implants have been thought to be safe and to have little toxicity, antigenicity, or adverse side effects. However, similar implants have been shown to cause nonspecific granulomatous reactions when implanted into bone or soft tissues in studies in both animals and human beings. This article reports the adverse effects of these implants in six shoulders of five patients who had repair of a damaged glenoid labrum. All patients reported increasing pain and loss of shoulder motion after insertion of these devices. All required a further arthroscopic lavage and debridement to reduce the inlracapsular synovitis. Granulomatous reactions were identified histologically in all cases. No long-term side effects were encountered, and all patients recovered satisfactorily.