Clinical, epidemiologic and bacteriologic observations of an outbreak of methicillin-resistant staphylococcus aureus at a large community hospital

A rabbit model for methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis was used to compare treatment with daptomycin, a new peptolide, and vancomycin. Daptomycin (4 mg/kg) and vancomycin (40 mg/kg) were injected subcutaneously every 12 and 6 h, respectively. After treatment, MRSA was found in bone cultures from 18 of 18 control rabbits, 10 of 17 animals treated with daptomycin, and 11 of 18 animals treated with vancomycin. Drug concentrations were measured in serum, uninfected bone, and infected bone 1 h after daptomycin or vancomycin was injected in a group of rabbits that had been infected for 3 to 4 weeks. Vancomycin was present at the highest concentrations in infected and uninfected bone. The results of this study suggest that daptomycin was similar to vancomycin in the eradication of MRSA from infected bone in an experimental model of osteomyelitis.

Section: Discussionmentioning

confidence: 99%

“…Methicillin-resistant Staphylococcus aureus (MRSA) causes a variety of infections, including osteomyelitis (8)(9)(10)(11)(16)(17)(18). Heretofore, vancomycin has been the only reliable antibiotic available for treating MRSA infections (16,17).…”

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confidence: 99%

Comparative evaluation of daptomycin (LY146032) and vancomycin in the treatment of experimental methicillin-resistant Staphylococcus aureus osteomyelitis in rabbits

Mader

Adams

1989

“…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.…”

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confidence: 98%

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

Cleary

Maurer

1978

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

“…The increased incidence of methicillin-resistant (Metr) Staphylococcus aureuis infections in the last 15 years has been well documented (7,11,18). Although the highest incidences have been confined to large teaching hospitals, small community hospitals have not completely escaped and actually may have higher incidences of Metr S. aureu.s infections than reported because of the lack of ongoing infection control programs (4,5).…”

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confidence: 99%

Comparison of the activities of coumermycin, ciprofloxacin, teicoplanin, and other non-beta-lactam antibiotics against clinical isolates of methicillin-resistant Staphylococcus aureus from various geographical locations

Aldridge¹,

Janney²,

Sanders³

1985

One hundred clinical isolates of methicillin-resistant (Metr) Staphylococcus aureus from five different geographical origins were tested for their susceptibility to 12 non-li-lactam antibiotics by the broth microdilution technique recommended by the National Committee for Clinical Laboratory Standards.Coumermycin and rifampin showed the highest activity with of MIC90s of 0.032 jig/ml for each compound. No resistance was found to coumermycin, whereas a single Metr S. aureus strain was found to be resistant to rifampin. Ciprofloxacin, vancomycin, and teicoplanin were the next most active compounds with MIC90s of 0.25, 0.5, and 0.5 ,ug/ml, respectively. Norfloxacin was less active, with an MIC90 of 1.0 ,ug/ml. Amikacin was the most active aminoglycoside tested, whereas high levels of resistance were found to tobramycin and gentamicin. Doxycycline and chloramphenicol showed variable results. Geographical variations in results were seen with doxycycline, chloramphenicol, and aminoglycosides. Kill-curve studies showed that coumermycin, ciprofloxacin, teicoplanin, vancomycin, and rifampin were highly bactericidal; more than 90% of the inoculum was killed within 8 h.