Antimicrobial Susceptibility Testing of Pneumococci: Determination of Kirby-Bauer Breakpoints for Penicillin G, Erythromycin, Clindamycin, Tetracycline, Chloramphenicol, and Rifampin

Jacobs, Michael; Mithal, Y.; Robins-Browne, R. M.; Gaspar, Miklos; Koornhof, H. J.

doi:10.1128/aac.16.2.190

Cited by 55 publications

(25 citation statements)

References 9 publications

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“…After the agar surface was dry, antimicrobial disks were applied, and the plates were incubated aerobically at 37°C for 18 h. The following disks (Difco Laboratories) containing antibiotics were used: penicillin, 2 U; tetracycline, 30 ,ug; erythromycin, 15 p.g; and chloramphenicol, 30 ,ug. The limits of the diameter of the halo for considering a strain susceptible were: penicillin, 30 mm; tetracycline, 20 mm; erythromycin, 20 mm; and chloramphenicol, 19 mm (7,8). When the sizes of the inhibiting halos were lower, determinations of the minimal inhibitory concentrations (MICs) were made for these antibiotics.…”

Section: Methodsmentioning

confidence: 99%

“…The inoculum was spread onto the agar by streaking in four directions with a sterile cotton swab previously soaked in the inoculum. After the agar surface was dry, antimicrobial disks were applied, and the plates were incubated aerobically at 37°C for 18 h. The following disks (Difco Laboratories) containing antibiotics were used: penicillin, 2 U; tetracycline, 30 ,ug; erythromycin, 15 by .6.2 iag/ml (7,8).…”

Section: Methodsmentioning

confidence: 99%

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Antimicrobial susceptibility of Streptococcus pneumoniae: serotype distribution of penicillin-resistant strains in Spain

Casal¹

1982

Antimicrob Agents Chemother

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This study examined the resistance to penicillin, tetracycline, erythromycin, and chloramphenicol of 318 pneumococcal strains isolated in Spanish hospitals from blood or cerebrospinal fluid of patients during 1979 to 1981. The serotypes of these strains were determined to discover whether a correlation between serotype and patterns of antibiotic resistance could be found. Seven and nine patterns of resistance were found in strains isolated from blood and cerebrospinal fluid, respectively; tetracycline was the most frequent pattern, followed by tetracycline associated with chloramphenicol. A random distribution of serotypes which was similar to the general distribution of serotypes was found for resistance to tetracycline and chloramphenicol, but penicillin-resistant strains were confined to seven serotypes. Thirty-six strains of penicillin-resistant pneumococci isolated from sources other than blood or cerebrospinal fluid were also serotyped. They represented the same serotypes, suggesting that serotype distribution among penicillin-resistant strains could be a manifestation of local epidemiological factors.Pneumococci have long been considered as naturally penicillin-susceptible microorganisms, such as group A hemolytic streptococci or meningococci. However, since 1965 (9), strains with a degree of resistance to penicillin have been isolated in many parts of the world (2, 5, 12); in some instances, these strains became resistant in the clinic (3, 11). The resistance to penicillin was frequently associated with resistance to other antibiotics, presenting new problems for clinicians. The South African outbreak in 1979 (1), where multiresistant strains were responsible for many cases of empyema and bacteremia together with pneumonia or meningitis, is perhaps the best example of these problems.In this paper, I examined the resistance to antibiotics of 318 pneumococcal strains isolated in Spanish hospitals from blood or cerebrospinal fluid (CSF) of patients during 1979 to 1981. The serotypes of these strains were identified to determine whether a correlation between serotype and the patterns of antibiotic resistance could be found. MATERIALS AND METHODSPneumococcal strains. A total of 318 pneumococcal strains were studied: 272 isolated from the blood of patients with symptoms of pneumonia and 46 from the blood or CSF of patients with meningitis. These strains were sent to my laboratory from 20 hospitals throughout Spain. Thirty-six pneumococcal strains isolated from other sources (pleural fluid and exudates from otitis, appendicitis, conjunctiva, or the pharynx) were also studied. When these strains arrived in the laboratory, they were immediately subcultured on Mueller-Hinton medium plates (Difco Laboratories, Detroit, Mich.) supplemented with 5% sheep blood and incubated at 37°C for 18 h in a 5% CO2 atmosphere. An optochin disk was placed in the upper part of the streaked area.Susceptibility testing. A disk agar diffusion test and an agar dilution assay were both performed in MuellerHinton medium supplemented with...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Antimicrobial susceptibility of Streptococcus pneumoniae: serotype distribution of penicillin-resistant strains in Spain

Casal¹

1982

Antimicrob Agents Chemother

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“…Fewer errors were made with 1-, 2-, or 5-Iug erythromycin disks than with 10-or 15-[Lg disks; with 1-, 5-, or 10-pug tetracycline disks than with 25-, 35-, or 50-p>g disks; and with 2-, 5-, or 10-,ug chloramphenicol disks than with 25-, 30-, or 50-j±g disks (244). Although NCCLS standards include 15-pig erythromycin disks and 30-pug tetracycline and chloramphenicol disks (201), these data, based on errors in either direction and using divergent laboratory methods, cannot be used as a basis for changing the recommended disk concentrations for susceptibility testing of pneumococci against these agents, but suggest that this potential problem be addressed by laboratories that use the Stokes method, as these problems were not encountered with the NCCLS method (129).…”

Section: Disk Susceptibility Testingmentioning

confidence: 99%

Pneumococcal resistance to antibiotics

1990

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The geographic distribution of pneumococci resistant to one or more of the antibiotics penicillin, erythromycin, trimethoprim-sulfamethoxazole, and tetracycline appears to be expanding, and there exist foci of resistance to chloramphenicol and rifampin. Multiply resistant pneumococci are being encountered more commonly and are more often community acquired. Factors associated with infection caused by resistant pneumococci include young age, duration of hospitalization, infection with a pneumococcus of serogroup 6, 19, or 23 or serotype 14, and exposure to antibiotics to which the strain is resistant. At present, the most useful drugs for the management of resistant pneumococcal infections are cefotaxime, ceftriaxone, vancomycin, and rifampin. If the strains are susceptible, chloramphenicol may be useful as an alternative, less expensive agent. Appropriate interventions for the control of resistant pneumococcal outbreaks include investigation of the prevalence of resistant strains, isolation of patients, possible treatment of carriers, and reduction of usage of antibiotics to which the strain is resistant. The molecular mechanisms of penicillin resistance are related to the structure and function of penicillin-binding proteins, and the mechanisms of resistance to other agents involved in multiple resistance are being elucidated. Recognition is increasing of the standard screening procedure for penicillin resistance, using a 1-microgram oxacillin disk.

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“…Antibiotic susceptibility testing was routinely performed by the disk diffusion technique in Mueller-Hinton agar supplemented with 5% horse blood (13). An oxacillin disk of 1 ,ug correctly identified all strains with decreased susceptibility to penicillin.…”

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confidence: 99%

Evaluation of vancomycin for therapy of adult pneumococcal meningitis

Viladrich

Gudiol

Liñares

et al. 1991

Antimicrob Agents Chemother

238

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The emergence of pneumococci resistant to penicillin and other agents prompted us to evaluate intravenous vancomycin for the therapy of pneumococcal meningitis, which has an overall mortality of 30%. Eleven consecutive adult patients with cerebrospinal fluid (CSF)-culture-proven pneumococcal meningitis and positive initial CSF Gram stain were given intravenous vancomycin (usual dosage, 7.5 mg/kg every 6 h for 10 days). The MBCs of vancomycin ranged from 0.25 to 0.5 micrograms/ml. Early adjunctive therapy with intravenous dexamethasone, mannitol, and sodium phenytoin was also instituted. After 48 h of therapy, all 11 patients showed a satisfactory clinical response, although the CSF culture remained positive in one case; median trough CSF and serum vancomycin levels were 2 and 5.1 micrograms/ml, respectively, and trough CSF bactericidal titers ranged from less than 1:2 to 1:16. On day 3, one patient died of acute heart failure. Four patients had clinical failure at on days 4 (two patients), 7 (one), and 8 (one) of therapy; they all immediately responded to a change in antibiotic therapy. The remaining six patients were cured after 10 days of vancomycin therapy. At this point, median peak CSF and serum vancomycin levels were 1.9 and 18.5 micrograms/ml, respectively. A transient alteration of renal function occurred in two patients, and persistent slight hypoacusia occurred in three patients. In summary, 11 adults with pneumococcal meningitis were treated with vancomycin and early adjunctive therapy including dexamethasone. All patients initially improved, and 10 were ultimately cured of the infection. However, four patients experienced a therapeutic failure, which led to a change in vancomycin therapy.

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Antimicrobial Susceptibility Testing of Pneumococci: Determination of Kirby-Bauer Breakpoints for Penicillin G, Erythromycin, Clindamycin, Tetracycline, Chloramphenicol, and Rifampin

Cited by 55 publications

References 9 publications

Antimicrobial susceptibility of Streptococcus pneumoniae: serotype distribution of penicillin-resistant strains in Spain

Antimicrobial susceptibility of Streptococcus pneumoniae: serotype distribution of penicillin-resistant strains in Spain

Pneumococcal resistance to antibiotics

Evaluation of vancomycin for therapy of adult pneumococcal meningitis

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