Nontypeable bacteriophage patterns of methicillin-resistant Staphylococcus aureus involved in a hospital outbreak

Abstract

Of 93 strains of Staphylococcus aureus isolated from inpatient wards of Ismailia General Hospital, 48 (51 %) were proven to be methicillin resistant (MR). Of these MR S. aureus strains, 44 were isolated from patients and 4 were isolated from healthy carriers, who were newly arrived interns working in the same wards. Bacteriophage patterns of MR S. aureus were identified by using routine test dilution (RTD) and 100-fold dilutions (100 RTD) of phages. Of these 48 strains, 37 (75%) (33 from patients and 4 from interns) were nontypeable when using RTD and 100 RTD of phages. Of the other 11 strains, 8 were nontypeable by RTD of phages, but 5 of them had the phage pattern D11/1136 when tested by 100 RTD. Three strains had the phage pattern 3A/3C/55/71, and three strains had different phage patterns, 29/81, 96, and 95/D11. The finding of colonization with virulent MR S. aureus strains in interns working on the wards in which these patients were located suggested that new strategies for control of MR S. aureus nosocomial infections must be considered and evaluated.

Investigation of an outbreak caused by methicillin‐resistant Staphylococcus aureus in a cardiovascular surgery unit by ribotyping, randomly amplifed polymorphic DNA and pulsed‐field gel electrophoresis

“…For control of outbreaks, rapid, accurate and reproducible methods are needed for epidemiological typing of MRSA isolates (4). Conventional methods for tracing of transmission, such as antibiogram and phage typing, have limited value in clustering MRSA in a situation of rising prevalence of multiresistant strains of MRSA and limited typeability (4)(5)(6)(7). Several molecular typing methods have been applied, including restriction strains (4)(5)(6)(7).…”

“…Conventional methods for tracing of transmission, such as antibiogram and phage typing, have limited value in clustering MRSA in a situation of rising prevalence of multiresistant strains of MRSA and limited typeability (4)(5)(6)(7). Several molecular typing methods have been applied, including restriction strains (4)(5)(6)(7). Several molecular typing methods have been applied, including restriction endonuclease analysis of plasmid DNA (REAP) (2,5), ribotyping (8), and pulsed-field gel electrophoresis (PFGE) of genomic DNA (9)(10)(11)(12).…”

Combined Use of Ribotyping, PFGE Typing and IS431 Typing in the Discrimination of Nosocomial Strains of Methicillin‐Resistant Staphylococcus aureus

“…Within each hospital, the discrimination of individual clinical MRSA isolates is a basic requirement for the identification of the epidemiologically dominant strain and to trace the transmission route from one patient to another. For this purpose, phage typing has long been used throughout the world (4,22,47), and coagulase typing has been widely used in Japan (28). However, with these phenotypic typing methods, difficulties have been recognized such as the presence of untypable strains or limitations in the discriminatory power (22,47).…”

“…For this purpose, phage typing has long been used throughout the world (4,22,47), and coagulase typing has been widely used in Japan (28). However, with these phenotypic typing methods, difficulties have been recognized such as the presence of untypable strains or limitations in the discriminatory power (22,47). For example, phage typing often gives unsatisfactory results because of its limited typeability (1,22,24,47) and instability (1,22).…”

“…However, with these phenotypic typing methods, difficulties have been recognized such as the presence of untypable strains or limitations in the discriminatory power (22,47). For example, phage typing often gives unsatisfactory results because of its limited typeability (1,22,24,47) and instability (1,22). Coagulase typing also encounters untypable strains besides its limited discriminatory power; there has been a maximum of eight coagulase isotypes detectable with specific antisera so far available (43).…”