Chemical and physical factors influencing methicillin resistance of Staphylococcus aureus and Staphylococcus epidermidis

Sabath, L. D.

doi:10.1093/jac/3.suppl_c.47

Cited by 90 publications

(73 citation statements)

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“…In the other two strains, both the rifampin alone and all antibiotic combinations caused at least a 100-fold reduction in the number of CFU at both 24 and 48 h. DISCUSSION Vancomycin was the most consistently effective of the antibiotics tested against MR S. epidermidis, inhibiting all 100 strains at -3.12 ,ug/ ml. Other investigators (3,11) have also found uniform susceptibility of MR S. epidermidis to vancomycin. In this laboratory, Siebert et al…”

Section: Resultsmentioning

confidence: 79%

Susceptibility and Synergy Studies of Methicillin-Resistant Staphylococcus epidermidis

Ein

Smith

Aruffo

et al. 1979

Antimicrob Agents Chemother

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Methicillin-resistant Staphylococcus epidermidis is an important cause of cerebrospinal fluid shunt infections and prosthetic valve endocarditis. Agar dilution miniimum inhibitory concentrations were determined for 100 strains of methicillin-resistant S. epidermidis which were isolated from clinical specimens. Vancomycin inhibited all 100 strains at s3.12 pug/ml, whereas clindamycin inhibited only 46 strains at <12.5 pg/mL. Methicillin-resistant S. epidermidis strains were resistant to achievable levels of erythromycin, with 90 strains having a minimum inhibitory concentration of 23.12 pg/ml. Of the five cephalosporins and one cephamycin tested, cefamandole was the most active in vitro, inhibiting 97 strains at S25 pug/ml. Antibiotic synergism was examined by a quantitative bacterial time-kill method. Synergism (.102 kill by the combination over the most effective single antibiotic at 24 h) was demonstrated with vancomycin (1.56 pLg/ml) plus cefamandole (6.25 pLg/ml) in 14 of 14 strains, vancomycin plus cephalothin (6.25 pLg/ml) in 14 of 14 strains, vancomycin plus rifampin (0.008 to 0.012 pg/ml) in 6 of 12 strains, rifampin plus cefamandole in 9 of 12 strains, and rifampin plus cephalothin in 10 of 12 strains. The emergence of populations of bacteria resistant to 0.2 pug of rifampin per ml developed in three offive methicillinresistant S. epidermidis strains tested. The addition of either vancomycin, cephalothin, or cefamandole to the rifampin prevented the emergence of resistance in these three strains. Clinical trials of synergistic antibiotic combination therapy for serious methicillin-resistant S. epidermidis infections are indicated.Staphylococcus epidermidis has been well established as a pathogen in the urinary tract (8), wounds (18), and, most importantly, infections involving indwelling artificial devices. S. epidermidis is the most common cause of prosthetic hip infections (10), cerebrospinal fluid shunt infections (1, 12), and prosthetic valve endocarditis (14, 15).The incidence of methicillin resistance in clinical isolates of S. epidermidis has ranged from 10% (11)

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Section: Resultsmentioning

confidence: 79%

Susceptibility and Synergy Studies of Methicillin-Resistant Staphylococcus epidermidis

Ein

Smith

Aruffo

et al. 1979

Antimicrob Agents Chemother

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“…There are, however, several factors that influence the in vitro determination of methicillin-resistance. These include the incubation temperature, the incubation time, the inoculum size, and the salt concentration of the test media (1,11,19,21). Because ofthese factors it was predicted that the determination of methicillin resistance by the automated system Autobac I might not give valid results (22).…”

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confidence: 99%

“…It has been reported that cultures of methicillin-resistant S. aureus represent a heterogeneous population of susceptible and resistant cells (8,19,20). The results of this study suggest that organisms with a lower LSI have a greater population of methicillin-resistant cells in the inoculum.…”

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confidence: 99%

Methicillin-Resistant Staphylococcus aureus Susceptibility Testing by an Automated System, Autobac I

Cleary

Maurer

1978

Antimicrob Agents Chemother

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The Autobac I system was used to evaluate the antibiotic susceptibility pattern of methicillin-resistant Staphylococcus aureus isolates. The results of the Autobac I were compared with the results of the disk diffusion method. The disk diffusion susceptibility pattern showed resistance to methicillin/oxacillin, penicillin, erythromycin, clindamycin, and kanamycin. All isolates were susceptible to cephalothin, chloramphenicol, tetracycline, and gentamicin. There was at least 96% agreement using the Autobac I system with all antibiotics except methicillin and clindamycin. When penicillinase-resistant, semisynthetic penicillins came into general use in the early 1960s, naturally occurring strains of Staphylococcus aureus resistant to these agents were found (12,13,18). Such strains became of epidemiological importance in England, Europe, and Ethiopia (18). However, the expected increased prevalence of these organisms in the United States did not appear. Several small outbreaks have been reported in hospitals in the United States, the first being at Boston City Hospital in 1967-1968 (2). Subsequent outbreaks (14, 17) and sporadic cases (5, 6) have been reported.Resistance to methicillin/oxacillin in S. aureus is poorly understood. It is known that antibiotic inactivation by enzymes is not a mechanism for resistance. There are, however, several factors that influence the in vitro determination of methicillin-resistance. These include the incubation temperature, the incubation time, the inoculum size, and the salt concentration of the test media (1,11,19,21). Because ofthese factors it was predicted that the determination of methicillin resistance by the automated system Autobac I might not give valid results (22).Recently, increased numbers of methicillinresistant S. aureus organisms have been isolated from our in-patient population. These isolates were examined with the Autobac I system, and the results were compared with other antibiotic susceptibility testing methods.MATERIALS

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“…Much more data are available for S. aureus than for the other species of staphylococci (Barry and Badal, 1977;McDougal and Thornsberry, 1984;Sabath, 1977;Thornsberry et al, 1973;Thornsberry and McDougal, 1983). Staphylococcus aureus, which are clearly resistant to nafcillin (or oxacillin or methicillin), also show resistance to cephalosporins by in vitro bactericidal assays and in the clinical setting; it is, however, not clear from published data that the same statements can be made for the coagulase-negative staphylococci (Ein et al, 1979;Frongillo et al, 1984;Hansen, 1983;John and McNeill, 1980;Laverdiere et al, 1978).…”

Section: Discussionmentioning

confidence: 99%

Bactericidal action of nafcillin, vancomycin, and three cephalosporins against nafcillin-susceptible and nafcillin-resistant coagulase-negative staphylococci

Mordenti

Davis

Lammel

et al. 1986

Diagnostic Microbiology and Infectious Disease

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Chemical and physical factors influencing methicillin resistance of Staphylococcus aureus and Staphylococcus epidermidis

Cited by 90 publications

References 0 publications

Susceptibility and Synergy Studies of Methicillin-Resistant Staphylococcus epidermidis

Susceptibility and Synergy Studies of Methicillin-Resistant Staphylococcus epidermidis

Methicillin-Resistant Staphylococcus aureus Susceptibility Testing by an Automated System, Autobac I

Bactericidal action of nafcillin, vancomycin, and three cephalosporins against nafcillin-susceptible and nafcillin-resistant coagulase-negative staphylococci

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