Improved, computer-generated system for pyocin typing of Pseudomonas aeruginosa

Abstract

We applied numerical clustering algorithms to the selection of a new indicator strain set for the pyocin typing of Pseudomonas aeruginosa. The new indicator set is composed of selected indicator strains from the sets described in 1966 by Gillies and Govan (J. Pathol. Bacteriol. 91:339-345) and in 1974 by Jones, Zakanycz, Thomas, and Farmer (Appl. Microbiol. 27:400-406) and is designated the G-F set. This indicator set consists of 14 indicator strains which typed 99.5% of 114 test cultures, has a high degree of discrimination (10 patterns encompass 50% of the test strains), and provides 62.3% reproducibility of the same typing pattern in duplicate tests done on different days. The G-F set of indicator strains provides slightly higher percentages of typable cultures than either of the other two sets, has greater discriminatory capability, and is more reproducible than they are. We recommend that the G-F set of indicator strains be used instead of the two other sets for pyocin typing of P. aeruginosa. We also tested a recently described overlay procedure for pyocin testing of P. aeruginosa and found it to be superior to previous methods in that it is easier to perform, it provides answers in only 24 h instead of 48 h, and it can be used to type mucoid strains (which previous techniques could not readily do). Thus, the application of numerical clustering algorithms and use of a revised typing procedure have produced an improved system for pyocin typing of P. aeruginosa. Similar procedures may be applicable to other typing systems.

Restriction endonuclease analysis of clinical Pseudomonas aeruginosa strains: useful epidemiologic data from a simple and rapid method

“…Classic methods have mostly relied upon phenotypic traits. None of these techniques is capable of typing all strains, and each technique generally yields rather broad categories (4,14,17,19,20,24,32).…”

Arbitrary primed PCR fingerprinting and serotyping of clinicalPseudomonas aeruginosastrains

“…Typing to evaluate the probability of cross‐transmission is commonly advised in epidemiological investigations, and the use of very discriminatory typing methods is recommended for differentiating epidemiologically unrelated isolates. It is widely accepted that traditional phenotypic methods of typing isolates of P. aeruginosa [5, 7, 8]do not permit accurate investigation of nosocomial infections because phenotypic markers are relatively unstable. In contrast, molecular subtyping methods offer high typeability and reproducibility, can define clonal relationships between isolates, and have contributed significantly to a better understanding of the epidemiology of P. aeruginosa infections [9–18, 21, 22, 25, 31].…”

“…This serotyping scheme characterizes most strains of P. aeruginosa possessing smooth LPS, although shows poor discrimination against rough LPS isolates which are common in patients with cystic fibrosis [5, 6]. Other conventional available systems based on phenotypic markers, such as biotyping, pyocin‐typing, phage‐typing, or antimicrobial susceptibility may not give satisfactory answers to basic epidemiological questions as they rely on the analysis of characteristics that are not stably expressed [7, 8].…”

Evolutionary and ecological role of extracellular contractile injection systems: from threat to weapon

“…Importantly, during this period, it was found that R-type pyocins have a more efficient killing activity than headless mutants of a related phage, supporting the hypothesis that these particles are not simply defective prophages but evolved weapons ( Shinomiya and Shiga, 1979 ). Additionally, their advantage for medical use was explored, employing pyocins for P. aeruginosa typing ( Farmer and Herman, 1969 ; Rose et al, 1971 ; Edmonds et al, 1972 ; Lovrekovich et al, 1972 ; Jones et al, 1974 ; Duncan and Booth, 1975 ; Bruun et al, 1976 ; Fyfe et al, 1984 ; Schable et al, 1986 ) as well as a potential treatment against P. aeruginosa infections ( Merrikin and Terry, 1972 ; Haas et al, 1974 ). In addition to all these findings, a new type of phage tail-like pyocin, the F-type, was discovered ( Takeya et al, 1969 ; Govan, 1974b ; Kuroda et al, 1979 ; Kuroda and Kageyama, 1979 , 1981 ; Michel-Briand and Baysse, 2002 ; Saha et al, 2023 ).…”