Comparative study of erythromycin, amoxicillin and ampicillin antimicrobial activity against human respiratory tract pathogens.

An in vitro test system was used to compare the antimicrobial activity of erythromycin, amoxicillin and ampicillin against respiratory tract pathogens isolated from man. The minimum inhibitory concentrations (MICs) of fresh clinical isolates of Streptoccus pyogenes, Streptocuccus pneumoniae, Staphylococcus aureus and Haemophilus influenzae to the macrolide and penicillins ranged between 0.01 and 0.9 microgram/ml. The microbes were exposed to each antibiotic for approximately 3 h at 1x,2x and 5x the relevant MIC. Irreversible surface defects and intracellular lesions were resolved by scanning and transmission electron microscopy in all antibiotic-treated bacterial species, irrespective of the antimicrobial used. In each case, inhibition of growth was recorded by turbometric assay; no significant difference was observed among the declining slopes of post-dosing growth curves for either erythromycin-, amoxicillin- or ampicillin-treated pathogens. The experimental observations show that the onset of antimicrobial activity and the bactericidal effectiveness of equipotent concentrations of erythromycin, amoxicillin and ampicillin were comparable in this study. The results complement previous clinical, bacteriologic and ultrastructure studies in vivo and demonstrate the contribution of the combined in vivo/in vitro study design for better understanding of antimicrobial activity in human respiratory tract infections.

[1]  J. Murdoch.  A Short Review of Erythromycin , 1977 .

[2]  J. Gould.  Erythromycin in Respiratory Tract Infection , 1977, Scottish medical journal.

[3]  M. Hayat,et al.  Principles and Techniques of Electron Microscopy: Biological Applications , 1975 .

[4]  J. Strominger,et al.  Interaction of penicillin with the bacterial cell: penicillin-binding proteins and penicillin-sensitive enzymes. , 1974, Bacteriological reviews.

[5]  M. Bergeron,et al.  An in vitro and pharmacological comparison of amoxicillin and ampicillin , 1974, The American journal of the medical sciences.

[6]  A. Weinstein,et al.  The pathophysiology and pathoanatomy of reactions to antimicrobial agents. , 1974, Advances in internal medicine.

[7]  Strominger Jl.  The actions of penicillin and other antibiotics on bacterial cell wall synthesis. , 1973 .

[8]  B. Weisblum,et al.  Antibiotic Inhibitors of the Bacterial Ribosome , 1968, Bacteriological reviews.

[9]  A. Bauer,et al.  Antibiotic susceptibility testing by a standardized single disk method. , 1966, American journal of clinical pathology.

[10]  A. Kisch,et al.  Observations on Bacteriostatic and Bactericidal Action of Erythromycin.∗ , 1958, Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine.

[11]  Sylvester Jc,et al.  Antibiotic bactericidal studies, I. Effect of methods on apparent bactericidal concentrations. , 1958 .

[12]  G. Hobby,et al.  Observations on the mode of action of oleandomycin. , 1958, Antibiotics annual.

[13]  T. Haight,et al.  Observations on Mode of Action of Erythromycin.∗ , 1952, Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine.

[14]  J. Geraci,et al.  Some laboratory and clinical observations on a new antibiotic, erythromycin (ilotycin). , 1952, Proceedings of the staff meetings. Mayo Clinic.

[15]  L. Goodman,et al.  THE PHARMACOLOGICAL BASIS OF THERAPEUTICS , 1966 .