Methicillin-Resistant Strains of Staphylococcus aureus Phage Type 92

Abstract

Methicillin-resistant (Mec r ) strains of Staphylococcus aureus received for phage typing from several hospitals in New York City were resistant to the international set of typing phages but susceptible to experimental phage 92. Subsequently, strains of type 92 were detected in two outbreaks with Mec r strains in two other locations in the United States. In all instances, type 92 was predominant among the Mec r strains isolated in each hospital. With the exception of one strain, the methicillin resistance of the Mec r strains investigated was homogeneous. In most instances, isolates from the same hospital were closely similar in their antibiotic resistance patterns. The strains isolated in New York City could be divided into three groups by the host range of their lysogenic phages and by antigenic structure. Transduction experiments indicated that the transfer of chromosomal tetracycline resistance from Mec r strains into a strain susceptible to several international typing phages renders the latter nontypable. However, the acceptor strain remains susceptible to experimental phages 92 and 88. Transduction of methicillin resistance had no effect on the phage susceptibility of the acceptor strain. It is possible that the presence of chromosomal tetracycline resistance is a determining factor in the phage susceptibility of Mec r strains isolated in New York City.

In vitro evaluation of the antimicrobial efficacy of a new silver-triclosan vs a silver collagen-coated polyester vascular graft against methicillin-resistant Staphylococcus aureus

“…Therefore, our conclusions are valid only for Gram-positive cocci, but no statement can be made about Gram-negative and -positive bacteria. However, because S aureus is the most common pathogen causative for vascular graft infection [25][26][27][28][29] and methicillin resistance is rapidly increasing worldwide, 46 preventing S aureus vascular graft infections is of particular relevance.…”

“…For the purpose of the experimental study, the ATCC 33591 (American Type Culture Collection, Manassas, Va) strain of methicillin-resistant Staphylococcus aureus (MRSA) was used because S aureus is the most commonly reported pathogen responsible for vascular graft infection, [25][26][27][28][29] and the presence of a mec A gene counteracts clinical efficacy of perioperative antibiotic prophylaxis with all ␤-lactam antibiotics.…”

Methicillin-resistant Staphylococcus aureus strains in New York City hospitals: inter-hospital spread of resistant strains of type 88

“…A comparison of phage types and resistance patterns of MRSA strains isolated in New York City over a period of 6 years indicated major shifts in jboth the predominant phage types and resistance spectra. The first methicillin-resistant strains received by our laboratory were of experimental phage type 92 (17). The strains of type 92 were predominantly gentamicin susceptible.…”

“…resistance on agar plates with 10 ,ug each of methicillin and gentamicin per ml. Representative MRSA strains and, in some instances, methicillin-susceptible isolates of the same phage type as the MRSA strains were tested in the same manner as in previous surveys (3,16,17) for susceptibility to each of the following: amikacin, chloramphenicol, clindamycin, erythromycin, gentamicin, penicillin, rifampin, tetracycline, trimethoprim-sulfamethoxazole, and vancomycin.…”

“…This survey began in 1977 when the first MRSA strains were received by our laboratory. Initially (1977 to 1978), we received strains of phage type 92 from six hospitals (17), with a relatively large number of isolates at two hospitals. to 1980, the number of hospitals with MRSA strains increased to 10.…”