Further use of deoxyribonuclease in a screening test forSerratia

Abstract

SYNOPSISThe deoxyribonuclease (DNase) test is useful in classifying Serratia bacilli and in differentiating it from the Hafnia group, E. cloacae, and E. liquefaciens. It is recommended as a differential test in enteric bacteriology because of its specificity, the convenience of its use, and the rapidity with which it can be performed.Although the deoxyribonuclease (DNase) test has been used primarily as a test to determine potentially pathogenic staphylococci (Elston and Fitch, 1964;Fusillo and Weiss, 1959; Weckman and Catlin, 1957) it shows potential as a diagnostic tool in identifying Serratia species. This is particularly true of nonpigmented strains. Production of DNase has been associated mainly with pathogenic cocci (Brown, 1950;Cunningham, 1959;Fusillo and Weiss, 1959;Potter and Laskowski, 1959; Wannamaker, 1958; Weckman and Catlin, 1957) but a wide variety of microorganisms has been found to produce this enzyme. These have included Bacillus subtilis, Clostridium septicum, Corynebacterium, Pasteurella pestis, Pseudomonas, Achromobacter, Escherchia coli, and Serratia marcescens. In recent years, DNase production in Enterobacteriaceae has been investigated in greater detail (Lehman and Richardson, 1964;Rothberg and Swartz, 1965; Valu, 1966).From time to time reports have appeared in the literature of the isolation of Serratia from such clinical sources as abscesses, blood, sputa, urine, and wounds. Many of the Serratia strains recovered today are without pigmentation (pigments) and are late or nonlactose fermenters making cultural differentiation from some of the other enterobacteria difficult. Serratia are closely allied in their physiological behaviour with Hafnia species (Paracolobactrum aerogenoides) and some members of the Enterobacter (Aerobacter) group which may make a long series of biochemical procedures necessary to identify these organisms. A short set of routine tests, which includes DNase as a major differentiating factor, would be especially useful as a screening Received for publication 3 July 1967. procedure in characterizing Serratia in a short period of time.The present work was undertaken to explore further this potential. MATERIALS AND METHODSNinety-three different strains (isolates) were used. These strains consisted of 51 determined species of Serratia, 33 determined species of Hafnia, six Enterobacter cloacae, and three Enterobacter liquefaciens organisms. Eighty-seven strains were fresh isolates obtained by the authors, while four were received from other laboratories, and one E. cloacae, and one E. liquefaciens strain were from the American Type Culture Company.Routinely, Gram-negative bacilli isolated in our laboratory are subjected to six routine tests which form a basic combination helpful in determining other biochemical tests to be used in further identification of these organisms. These tests included: Kligler iron agar (Difco) used to determine the production of hydrogen sulphide, and the fermentation reaction on the slant (lactose) and in the butt (glucose) of the ...

Evaluation of three methods using deoxyribonuclease production as a screening test forSerratia marcescens

“…95, more sensitive but less specific than the two modifications. Once again, the production of weak positive reactions by Proteus and Alkaligenes species is relatively unimportant but it was surprising to find this type of reaction given by both Enterobacter liquefacienis strains tested as this has not been mentioned by other workers (Rothberg and Swartz, 1965;Elston and Elston, 1968). These weak positive reactions were, however, easily distinguishable from those given by Serratia marcescens.…”

“…In practice, this differentiation is usually made on the ability of Serratia marcescens to liquefy gelatin rapidly, and on its inability to ferment arabinose, raffinose, or rhamnose (Edwards and Ewing, 1962). The demonstration, however, that deoxyribonuclease (DNase) production is a characteristic of Serratia marcescens but not of the other members of the K-E-S division (Rothberg and Swartz, 1965;Elston and Elston, 1968) represented a major advance in the biochemical identification of this group since it meant that, for the first time, there was available a test which was sufficiently specific and straightforward to be of value as a screening procedure. Recently some modifications of the original test have been suggested (Schreier, 1969;Smith, Hancock, and Rhoden, 1969), and, since in this laboratory for the past few months we have been engaged in determining the exact incidence of Serratia marcescens in our clinical material (Black and Hodgson, 1970), it was thought that this presented an ideal opportunity for comparing the usefulness of the original test and these two modifications in the bacteriological identification of Serratia marcescens.…”

A new, simple, rapid test for detection of DNase activity of microorganisms: DNase Tube test

“…The DNase test aids in the differentiation of closely-related genera within the Klebsiella Enterobacter Serratia division of Enterobacteriaceae and several other pathogens, including P. aeruginosa, Aeromonas spp., Clostridium spp. and M. catarrhalis (Elston and Elston, 1968;Fusillo and Weiss, 1959;MacFaddin, 2000). A short set of routine tests, which includes DNase as a major differentiating factor, would be especially useful as a screening of microorganisms including Corynebacterium species (Pimenta et al, 2008).…”

Degradation of Nuclease-Stabilized RNA Oligonucleotides in Mycoplasma-Contaminated Cell Culture Media

“…DNase activity has in fact been used to differentiate among various bacterial pathogens, including the identification of coagulase-positive staphylococci, such as Staphylococcus aureus, in bovine milk samples (Elston and Elston, 1968;Boerlin et al, 2003). Such assays depend on the isolation of the bacteria from biological fluids and tissues that also contain DNases, which would otherwise generate background; isolation and culture of the bacteria can consume valuable time.…”