Effect of Antibacterial Agents on the Autoplaque Phenomenon of Pseudomonas Aeruginosa

Abstract

A survey of 75 cultures of Psezrdomonas nerztgi~zosa containing only one discernible phenotype indicated that 68 routinely eshibited spontaneous lysis, resulting in the appearance of turbid erosions or autoplaques (AP+) when grown on a tryptone-glucose agar nlediun~. Single supplements of 11011-inhibitory levels of chloromycetin, aureomyclll, tetracycline, declomycin, and streptomycin increased the degree of lysis of AP+ strains, but were without effect on APstrams. Enhancement of lysis was also obtained with sulfadiazine, sulfathiazole, s u l f a~l~e t h o s )~p y r i d a z i~~e , elkosin, gantrisin, and triple sulfa, while little or no effect was observed with sulfamerizine and thiosulfil. On the other hand, low conce~ltrations of either acriflavine or proflavine retarded the rate and degree of lysis, while single supplenlents of the active antibiotics overcame the suppressive effects of the dyes.One of the common cultural characteristics associated with many strains of Pseudomonas aeruginosa is the spontaneous production of turbid plaque-like erosions on themselves when cultivated on tryptone agar media (7, 17). As an expression of this self-lysis the term autoplaque (AP+) has been adopted t o differentiate this lytic phenomenon from the plaques noted when phage is plated on a sensitive indicator strain. Some of the unusual properties of the lytic systelu are manifested in the following way: size and numbers of autoplaques increase with time; lysis in many strains is accompanied by a metallic iridescence; AP+ strains remain permanently autolytic although they are never completely destroyed; and the system is highly variable in appearance from culture t o culture, as well a s within a given culture from day t o day. The mechanism by which lysis occurs is a t present unknown, although phage, bacteriocines, and enzymes have been previously investigated (2) ; however, no one has been able t o duplicate the phenomenon with any of the above preparations. Consequently, a nutritional approach t o the study is presently underway in a n effort t o clarify and better characterize the lytic phenomenon. Previous studies by Berk (1) attempted t o discern the nutritional requirements necessary for support of growth in the presence and absence of self-lysis. Growth in a minimal tryptone medium could be obtained without lysis if the tryptone concentration was reduced t o 0.1 t o 0.5yo. Lytic activity was restored by single supplements of asparagine or arginine. The present paper deals with the stimulatory effect of certain antibiotics and sulfa drugs, and the suppressive effect of acridine dyes when supplemented t o AP+ cells cultivated on media nutritionally adequate for support of growth and lysis. Materials and MethodsOrganisms.-The cultures of P. aerzlginosa used in this study were obtained from various clinical sources and the departmental stock culture collection. Each culture was streaked for isolated colonies and a pure culture of each Canadian Journal of Microbiology. Volume 11 (1965) Can. J. Microbiol. Downloaded f...

Prevalence of Autoplaque Phenomenon in Bacterial Communities from Spatially Heterogeneous Environment of an Abandoned Mine

“…But the isolates failed to show autoplaque phenomenon without any sub-culturing. In another study, 90.66% of P.aeruginosa isolates showed autolysis when grown in specifically in tryptone-glucose agar medium (Berk, 1965). Similarly, 92% of P. aeruginosaisolates (46 out of 50 isolates) showed spontaneous lysis and produced turbid, iridescent auto-plaques (AP + ) (Berk and Gonkowski, 1964).…”

“…Further, a bacterial species also sustainably varies in the level and type of autoplaque depending on the culture conditions and environmental source of bacteria. For example, 90% of Pseudomonas arugenosa isolates (18 out of 20 isolates) showed autoplaque that too only after several sub-culturing (Berk, 1963). But the isolates failed to show autoplaque phenomenon without any sub-culturing.…”

“…However, Berk (1966) also showed that the self-lysis becomes more obvious when the bacteria are cultivated on complex growth media. Also, the synthetic chemicals (antibiotics, antiseptics, disinfectants) in low concentration (noninhibitory levels) also increased the degree of lysis but a low concentration of antiseptic and disinfectant bacteriostatic retarded the rate and degree of lysis (Berk, 1965). Similarly, Breyen and Dworkin (1984) showed elevated temperature, and light condition failed to induce this phenomenon.…”

“…As compared with the bacterial community associated with low particle size fraction (clay).Different studies have shown contradictory views on the role of nutrient and environmental factors to drive autoplaque phenomenon in bacteria. For examples, the classical studies from Berk (1963Berk ( , 1965 suggested an influence of nutrient on autoplaque production; however, Heurlier et al, (2005) suggested the lack of any effect of nutrients on autoplaque production (Heurlier et al, 2005). However, Berk (1966) also showed that the self-lysis becomes more obvious when the bacteria are cultivated on complex growth media.…”

“…The autoplaquephenomenon has been intriguing microbiologists for more than five decades (Berk, 1963;Krylov et al, 2016). The autoplaquephenomenon is characterized by the spontaneous appearance of plaques on the bacterial lawn without exposure to any external phage.…”