Journal of Antimicrobial Chemotherapy (1976) 2, 55-59
Antibacterial activity of eight cephalosporins against Haemophilus influenzae and Streptococcus pneumoniae E. Yourassowsky, E. Schoutens and M. P. Vanderlinden
Two hundred recent clinical isolates of Haemophilus and Pneumococcus were tested in vitro against eight cephalosporins by means of disc diffusion and agar dilution tests. In the case of Haemophilus, the most active drug (cefamandole) was 100 times as active as the least effective one (cephalexin). Many strains were resistant to cephradine and cephalexin. The most active cephalosporins against Streptococcus pneumoniae were cephaloridine, cephapirin, cefazolin, cefamandole and cephalothin. Cefoxitin, cephradine and cephalexin were clearly less active. Nevertheless, none of the strains were clearly resistant to these drugs. Introduction
Although changing prevalence of pathogenic bacteria in several infections is a widely accepted notion (Finland, 1970) by far the commonest bacterial pathogens in chronic bronchitis still remain Haemophilus influenzae and Streptococcus pneumoniae (May, 1968). Until recently, the remarkable sensitivity patterns of these two bacteria (Sabath, Stumpf, Wallace & Finland, 1970; Yourassowsky, Schoutens, Vanderlinden & Prudhomme, 1975) were considered sufficiently constant to justify blind chemotherapy with ampicillin in the routine management of chronic bronchitis. Unfortunately, ampicillin resistant Haemophilus are now encountered (Schiffer, McLowry, Schneerson & Robbins, 1974) which makes this therapeutic option hazardous. Moreover this drug cannot be used in patients hypersensitive to penicillin. As cephalosporins could be an alternative choice in such cases, the present study was undertaken to compare the in vitro activity of several examples of this group of antibiotics against recent clinical isolates of Strept. pneumoniae and Haemophilus influenzae. Materials and methods
The strains were mostly isolated from transtracheal aspirations, sputum and throat swabs. They were preserved in liquid nitrogen until sensitivity testing. Included in the survey were 100 strains of Strept. pneumoniae and 100 strains of Haemophilus influenzae. Antibiotics were furnished as follows: cefamandole, cephalexin, cephaloridine and cephalothin, Lilly; cefazolin, Bristol; cefoxitin, Merck, Sharp and Dohme; cephapirin, 55
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Hopital Universitaire Brugmann, 1020-Bruxelles, Belgium
56
E. Yourassowsky, E. Schoutens and M. P. Vanderlinden
Results MIC values of the Haemophilus strains are summarized in Figure 1. Of the eight cephalosporins tested, cefamandole is the most active with 97 % of the strains inhibited by 0-78 ug/ml. In order of decreasing bacteriostatic effectiveness, the 100 -
90 g 80
s § 8
70
60 •8
i
50
40 H. Influenzas o cepbololhin
f 3°
• ceptaiortdine A cephalexln
9 • o • x
20
ceptapirin cefozolin cefoxitin cephrodine cefomandols
10 I
I . I
I
1
I
I
I
0024 0 0 9 0-39 156 6-25 25 100 Minimum inhibitory concentration (^ig/ml) Figure 1. Activity of eight cephalosporins against 100 strains of Haemophilus.
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Mead-Johnson and cephradine, Squibb. Minimum inhibitory concentrations (MIC) were determined by an agar plate dilution method using trypticase soy agar supplemented with 2% Fildes enrichment for Haemophilus strains, and Mueller Hinton agar supplemented with 5 % horse blood for Pneumococcus strains. Overnight broth cultures in Mueller Hinton broth supplemented with 5% Fildes enrichment were diluted to contain 10s organisms per ml. The plates were inoculated with an automatic multipoint inoculator (Dynatech, Billingshurst, Sussex, England). Results were read after 18 h incubation in an atmosphere of 10% CO2. The MIC was determined as the lowest concentration yielding no growth. Antibiotic sensitivity testing was also performed by the filter-paper-disc method using 30 ug discs and the same media as in MIC determinations. Diameters of the inhibition zones were measured with calipers after overnight incubation in a CO2 enriched atmosphere.
Cephalosporins and respiratory programme
57
other drugs can be classified as follows: cephapirin, cephalothin, cefoxitin, cephaloridine, cefazolin, cephradine and cephalexin. Mean values and standard deviations of the zone diameters obtained with the Haemophilus strains are: cephalothin: 29-73 (±5-77) mm cephapirin: 29-38 (±5-60) mm, cefoxitin: 2816 (±5-40) mm, cephaloridine: 27-39 (±518) mm,cefamandole: 25-91 (±3-63) mm,cefazolin: 25-35 (±5-42) mm, cephradine: 23-49 (±3-86) mm, cephalexin: 2316 (±4-85) mm. Cephalexin and cephradine are the least effective drugs with many resistant strains (MIC >25 ug/ml, zone diameter o
6-25
i
1 56
I §
0 39
o £• 0097 o 5 0024 ,.nrmnn..n,,
0 006
R
10
14
18 24 28 32 36 40 44 48 52 Zone diameter (mm) Figure 4. Comparison of agar dilution with disk diffusion susceptibility tests for 100 Strept. pneumoniae strains against cephalondine and cephalexin. G, cephaloridine; • , cephalexin.'
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
1 1 11 1 lI l l1l \il J
? %
I
Cephalosporins and respiratory programme
59
Discussion and conclusions
Acknowledgements The technical assistance of J. Schoonjans and her colleagues is gratefully acknowledged. References Bauer, A. W., Kirby, W. M. M., Sherris, J. C. & Turck, M. Antibiotic susceptibility testing by a standardized single disk method. American Journal of Clinical Pathology 45: 493-6 (1966). Finland, M. Changing ecology of bacterial infections as related to antibacterial therapy. Journal of Infectious Diseases 122: 419-31 (1970). Hamilton-Miller, J. M. T. & Brumfitt, W. Whither the cephalosporins? Journal of Infectious Diseases 130: 81-3 (1974). May, J. R. The Chemotherapy of Chronic Bronchitis and Allied Disorders. The English Universities Press Ltd, London (1968). Sabath, L. D., Stumpf, L. L., Wallace, S. J. & Finland, M. Susceptibility of Diplococcus pneutnoniae, Haemophilus influenzae, and Neisseria meningitidis to 23 antibiotics. Antimicrobial Agents and Chemotherapy 1970: 53-6. Schiffer, M. S., MacLowry, J., Schneerson, R. & Robbins, J. B. Clinical, bacteriological and immunological characterization of ampicillin-resistant Haemophilus influenzae type B. Lancet ii: 257-9 (1974). Williams, J. D. & Andrews, J. Sensitivity of Haemophilus influenzae to antibiotics. British Medical Journal 1: 134-7 (1974). Yourassowsky, E., Schoutens, E., Vanderlinden, M. P. & Prudhomme, M. R. Susceptibility of Haemophilus to antibiotics: present status. Infection 3: 15-8 (1975). (Manuscript accepted 12 November 1975)
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Striking differences in in vitro effectiveness are demonstrated among cephalosporins against two common respiratory pathogens: in the case of Pneumococcus, these drugs can be divided into two categories, the less effective including cefoxitin, cephradine and cephalexin. However, no resistant strains are encountered. In the case of Haemophilus, the most active drug (cefamandole) is 100 times as active as the least effective one (cephalexin), the other antibiotics of this group being evenly distributed between these two extremes. Many strains are resistant to cephradine and cephalexin. These data correlate well with those previously published by Williams & Andrews (1974). Clinical laboratories most often use the disk agar diffusion method (Bauer, Kirby, Sherris & Turck, 1966) as a routine technique for susceptibility testing. The present study suggests that prediction of the sensitivity of Pneumococcus strains to all cephalosporins on the basis of one drug of this group being tested alone (generally cephalothin) is a suitable procedure as each strain exhibits comparable sensitivities to the different antibiotics of this group. This is not true for Haemophilus, strains being encountered which are resistant to cephradine and cephalexin, although sensitive to cephalothin. It is difficult to extrapolate from laboratory results to clinical indications for therapy and that is not the purpose of the present paper. Cases in which cephalosporins would be the outstanding drugs of choice are still to be denned (Hamilton-Miller & Brumfitt, 1974). The eventual role of these antibiotics in the chemotherapy of pulmonary tract infections is likely to depend on further comparative trials of efficacy, toxicity and cost.
Antibacterial activity of eight cephalosporins against Haemophilus influenzae and Streptococcus pneumoniae E. Yourassowsky, E. Schoutens and M. P. Vanderlinden
Two hundred recent clinical isolates of Haemophilus and Pneumococcus were tested in vitro against eight cephalosporins by means of disc diffusion and agar dilution tests. In the case of Haemophilus, the most active drug (cefamandole) was 100 times as active as the least effective one (cephalexin). Many strains were resistant to cephradine and cephalexin. The most active cephalosporins against Streptococcus pneumoniae were cephaloridine, cephapirin, cefazolin, cefamandole and cephalothin. Cefoxitin, cephradine and cephalexin were clearly less active. Nevertheless, none of the strains were clearly resistant to these drugs. Introduction
Although changing prevalence of pathogenic bacteria in several infections is a widely accepted notion (Finland, 1970) by far the commonest bacterial pathogens in chronic bronchitis still remain Haemophilus influenzae and Streptococcus pneumoniae (May, 1968). Until recently, the remarkable sensitivity patterns of these two bacteria (Sabath, Stumpf, Wallace & Finland, 1970; Yourassowsky, Schoutens, Vanderlinden & Prudhomme, 1975) were considered sufficiently constant to justify blind chemotherapy with ampicillin in the routine management of chronic bronchitis. Unfortunately, ampicillin resistant Haemophilus are now encountered (Schiffer, McLowry, Schneerson & Robbins, 1974) which makes this therapeutic option hazardous. Moreover this drug cannot be used in patients hypersensitive to penicillin. As cephalosporins could be an alternative choice in such cases, the present study was undertaken to compare the in vitro activity of several examples of this group of antibiotics against recent clinical isolates of Strept. pneumoniae and Haemophilus influenzae. Materials and methods
The strains were mostly isolated from transtracheal aspirations, sputum and throat swabs. They were preserved in liquid nitrogen until sensitivity testing. Included in the survey were 100 strains of Strept. pneumoniae and 100 strains of Haemophilus influenzae. Antibiotics were furnished as follows: cefamandole, cephalexin, cephaloridine and cephalothin, Lilly; cefazolin, Bristol; cefoxitin, Merck, Sharp and Dohme; cephapirin, 55
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Hopital Universitaire Brugmann, 1020-Bruxelles, Belgium
56
E. Yourassowsky, E. Schoutens and M. P. Vanderlinden
Results MIC values of the Haemophilus strains are summarized in Figure 1. Of the eight cephalosporins tested, cefamandole is the most active with 97 % of the strains inhibited by 0-78 ug/ml. In order of decreasing bacteriostatic effectiveness, the 100 -
90 g 80
s § 8
70
60 •8
i
50
40 H. Influenzas o cepbololhin
f 3°
• ceptaiortdine A cephalexln
9 • o • x
20
ceptapirin cefozolin cefoxitin cephrodine cefomandols
10 I
I . I
I
1
I
I
I
0024 0 0 9 0-39 156 6-25 25 100 Minimum inhibitory concentration (^ig/ml) Figure 1. Activity of eight cephalosporins against 100 strains of Haemophilus.
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Mead-Johnson and cephradine, Squibb. Minimum inhibitory concentrations (MIC) were determined by an agar plate dilution method using trypticase soy agar supplemented with 2% Fildes enrichment for Haemophilus strains, and Mueller Hinton agar supplemented with 5 % horse blood for Pneumococcus strains. Overnight broth cultures in Mueller Hinton broth supplemented with 5% Fildes enrichment were diluted to contain 10s organisms per ml. The plates were inoculated with an automatic multipoint inoculator (Dynatech, Billingshurst, Sussex, England). Results were read after 18 h incubation in an atmosphere of 10% CO2. The MIC was determined as the lowest concentration yielding no growth. Antibiotic sensitivity testing was also performed by the filter-paper-disc method using 30 ug discs and the same media as in MIC determinations. Diameters of the inhibition zones were measured with calipers after overnight incubation in a CO2 enriched atmosphere.
Cephalosporins and respiratory programme
57
other drugs can be classified as follows: cephapirin, cephalothin, cefoxitin, cephaloridine, cefazolin, cephradine and cephalexin. Mean values and standard deviations of the zone diameters obtained with the Haemophilus strains are: cephalothin: 29-73 (±5-77) mm cephapirin: 29-38 (±5-60) mm, cefoxitin: 2816 (±5-40) mm, cephaloridine: 27-39 (±518) mm,cefamandole: 25-91 (±3-63) mm,cefazolin: 25-35 (±5-42) mm, cephradine: 23-49 (±3-86) mm, cephalexin: 2316 (±4-85) mm. Cephalexin and cephradine are the least effective drugs with many resistant strains (MIC >25 ug/ml, zone diameter o
6-25
i
1 56
I §
0 39
o £• 0097 o 5 0024 ,.nrmnn..n,,
0 006
R
10
14
18 24 28 32 36 40 44 48 52 Zone diameter (mm) Figure 4. Comparison of agar dilution with disk diffusion susceptibility tests for 100 Strept. pneumoniae strains against cephalondine and cephalexin. G, cephaloridine; • , cephalexin.'
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
1 1 11 1 lI l l1l \il J
? %
I
Cephalosporins and respiratory programme
59
Discussion and conclusions
Acknowledgements The technical assistance of J. Schoonjans and her colleagues is gratefully acknowledged. References Bauer, A. W., Kirby, W. M. M., Sherris, J. C. & Turck, M. Antibiotic susceptibility testing by a standardized single disk method. American Journal of Clinical Pathology 45: 493-6 (1966). Finland, M. Changing ecology of bacterial infections as related to antibacterial therapy. Journal of Infectious Diseases 122: 419-31 (1970). Hamilton-Miller, J. M. T. & Brumfitt, W. Whither the cephalosporins? Journal of Infectious Diseases 130: 81-3 (1974). May, J. R. The Chemotherapy of Chronic Bronchitis and Allied Disorders. The English Universities Press Ltd, London (1968). Sabath, L. D., Stumpf, L. L., Wallace, S. J. & Finland, M. Susceptibility of Diplococcus pneutnoniae, Haemophilus influenzae, and Neisseria meningitidis to 23 antibiotics. Antimicrobial Agents and Chemotherapy 1970: 53-6. Schiffer, M. S., MacLowry, J., Schneerson, R. & Robbins, J. B. Clinical, bacteriological and immunological characterization of ampicillin-resistant Haemophilus influenzae type B. Lancet ii: 257-9 (1974). Williams, J. D. & Andrews, J. Sensitivity of Haemophilus influenzae to antibiotics. British Medical Journal 1: 134-7 (1974). Yourassowsky, E., Schoutens, E., Vanderlinden, M. P. & Prudhomme, M. R. Susceptibility of Haemophilus to antibiotics: present status. Infection 3: 15-8 (1975). (Manuscript accepted 12 November 1975)
Downloaded from http://jac.oxfordjournals.org/ at University of Birmingham on June 9, 2015
Striking differences in in vitro effectiveness are demonstrated among cephalosporins against two common respiratory pathogens: in the case of Pneumococcus, these drugs can be divided into two categories, the less effective including cefoxitin, cephradine and cephalexin. However, no resistant strains are encountered. In the case of Haemophilus, the most active drug (cefamandole) is 100 times as active as the least effective one (cephalexin), the other antibiotics of this group being evenly distributed between these two extremes. Many strains are resistant to cephradine and cephalexin. These data correlate well with those previously published by Williams & Andrews (1974). Clinical laboratories most often use the disk agar diffusion method (Bauer, Kirby, Sherris & Turck, 1966) as a routine technique for susceptibility testing. The present study suggests that prediction of the sensitivity of Pneumococcus strains to all cephalosporins on the basis of one drug of this group being tested alone (generally cephalothin) is a suitable procedure as each strain exhibits comparable sensitivities to the different antibiotics of this group. This is not true for Haemophilus, strains being encountered which are resistant to cephradine and cephalexin, although sensitive to cephalothin. It is difficult to extrapolate from laboratory results to clinical indications for therapy and that is not the purpose of the present paper. Cases in which cephalosporins would be the outstanding drugs of choice are still to be denned (Hamilton-Miller & Brumfitt, 1974). The eventual role of these antibiotics in the chemotherapy of pulmonary tract infections is likely to depend on further comparative trials of efficacy, toxicity and cost.
