Epidemiological Fingerprinting of Pseudomonas aeruginosa by the Production of and Sensitivity to Pyocin and Bacteriophage

Abstract

A new method has been devised to trace cross-infection by Pseudomonas aeruginosa . Unknown strains growing logarithmically in liquid media were treated with mitomycin C to induce the liberation of pyocin and phage. The lysates were then tested against 27 selected indicator strains, and the zones of clearing were differentiated as to killing by pyocin or lysis by phage. Twenty-four standard pyocin-phage lysates were then applied to each of the unknowns, and the sensitivity pattern was recorded. Thus, an “epidemiological fingerprint” consisting of 51 operational characteristics was established for each isolate. Organisms from the same source had identical or similar fingerprints, but organisms from different origins could easily be distinguished. Pyocin production, pyocin sensitivity, and phage production were found to be stable genetic characters; however, spontaneous mutations in phage sensitivity were frequently encountered. The epidemiological fingerprint has proven to be a sensitive tool in establishing the identity or dissimilarity of unknown strains. This method has been of great value in tracing the epidemiology of P. aeruginosa in the hospital environment. Each of the 157 P. aeruginosa strains tested has been typable by this method.

Epidemiology of Pseudomonas aeruginosa infections: determination by pyocin typing

“…Our modified method tnat utilized 18 indicator strains was satisfactory for use in an epidemiological study. Certain pyocin zones were difficult to interpret, which has also been observed by others (11,23). Bergan noted that calcium supplements resulted in inhibition of more indicator strains and inhibition reactions that were easier to read (2).…”

“…Many methods have been proposed for typing P. aeruginosa. Bacteriophage typing is limited because of changes in lytic patterns due to mutation and dissociation (11,24). Serological typing has been proposed, but the method usually is not sensitive enough when used 'Present address: Ulleval Hospital, Oslo, Norway.…”

“…There have been studies using two or more methods (2,3). Various methods have been proposed based on either pyocin production or pyocin sensitivity of isolates (7,11,12,24). In the present investigations, a modification of the procedure of Farmer and Herman (11), which tests the pyocin production of P. aeruginosa cultures against a set of 27 indicator strains of P. aeruginosa, was utilized.…”

“…Typing by pyocin production. The method of Farmer and Herman (11) was used with the following exceptions. Trypticase soy broth cultures of organisms to be typed were grown with constant shaking at 32 C. After 1 h, 1 ml of filter-sterilized mitomycin C, 10 ,mg/ml, (Sigma Chemical Co., St. Louis, Mo.)…”

Ερευνα Επι Της Τυποποιησεως Της Pseudomonas Aeruginosa Δια Πυοσινοτυπιας - Οροτυπιας

“…Ή αξία της πυοσινοτυπίας ως μεθόδου τυποποιήσεως, ανεξαρτήτως της χρησιμοποιούμενης τεχνικής μεθόδου (Darreil and Wahba 1964, Gillies and Govan 1966), περιορίζεται έν μέρει καθ' δσον δι' αυτής άπομονοϋται διάφορον ποσοστόν στελεχών, κυμαινόμενον από 3,3 (Bergan 1973γ) εως 43% (Adler and Finland 1971), τα όποια χαρακτηρίζονται ως άτυποποίητα, ήτοι ώς μη άναστέλλοντα ούδένα των στελεχών-δεικτών. Παρά ταΰτα ή α δυναμία τής μεθόδου αυτής σχεδόν εκμηδενίζεται πλήρως δια τής χρήσεως περισσοτέρων των συνήθως χρησιμοποιουμένων προτύπων στελεχων-δει κτων (Paterson 1965, Farmer andHerman 1969). Ή παραγωγή βλεννώδους έξωκυτταρίου ουσίας (slime) ύπό των στελεχων-δεικτων προστατεύει ταύτα έκ τής δράσεως των πυοσινων μέ αποτέλεσμα τήν άποτυχίαν τής τυποποι ήσεως (Wahba 1963).…”