! NATURE, FORMATION, AND ACTIVITIES 



Table 31 

 Comparison of antibiotic sensitivity of three series of strains of Pseudonionas (Wright et al., 1954) 



* Series A = All strains isolated in 1949 and earlier. Series B = L>()])hilize(l strains isolated in 1949, 

 studied in 1954. Series C = Current strains, isolated December 1953 to May 1954. 



neamine was least active. There was much 

 variation among the different species and 

 strains. 



The increased use of antibiotics in clinical 

 practice leads to an increase in resistance of 

 bacteria. This is well illustrated in Table 34. 

 There is a difference, however, between 

 different organisms. Klebsiella, for example, 

 develops greater resistance than Escherichia. 

 The correlation between antibiotic sensi- 

 tivity tests and clinical results was examined 

 by Abboud and Waisbren (1959). 



Antibiotics have been grouped on the 

 basis of their antistaphylococcal properties 

 by Waisbren and St relit zer (1960) (Table 

 35). A detailed study of the behavior of new 

 antistaphylococcal agents has been made by 

 Garrod and Waterworth (195(3). 



Considerable work has been done and a 

 most extensive literature has accumulated on 



the sensitivity of the tuberculosis organism 

 Alycohacferium tuberculosis, to various anti- 

 biotics and other antimycobacterial agents. 

 Waksman and Lechevalier (1953) have 

 shown that the human and bovine forms of 

 M. tuberculosis are highly sensitive to iso- 

 niazid, the avian form is less sensitive, the 

 nonpathogenic mycobacteria are still less 

 sensitive, and the Nocardia and Streptomy- 

 ces species are fairly resistant. Pollak (1956) 

 reported that atypical acid-fast mycobac- 

 teria are sensitive to streptomycin and par- 

 tially or totally resistant to the synthetic 

 chemotherapeutic agents p-aminosalicylic 

 acid and isoniazid. 



IVIicrobiostatic versus Microbicidal Ac- 

 tivity of Antibiotics 



Antibiotics can kill microbial cells, or they 

 may simply prevent their multiplication. 



