Growth and Metabolism of Live Vaccine Strain of Pasteurella tularensis

Abstract

The growth and metabolism of the live vaccine strain of Pasteurella tularensis in different media were investigated. Maximal growth was observed in a medium containing a sulfuric acid digest of casein as amino acid source. Amino acid metabolism produced considerable ammonia, and the rate of ammonia evolution was directly proportional to the growth rate. The most likely route for amino acid breakdown is nonspecific oxidative deamination. Most studies on nutritional requirements of Pasteurella tularensis have been restricted to the virulent strains. Early research on the virulent strain was conducted in peptone-blood medium with cysteine enrichment (7). In blood-free medium, the organism required a generous supply of other amino acids in addition to cysteine. This requirement was satisfied by the incorporation of hydrolysates of gelatin or casein acid digest (9, 14; R. C. Mills et al., Bacteriol. Proc., p. 37, 1949) into the medium. Systematic study of amino acid requirement started with the development of chemically defined media. The first such medium was reported by J. T. Tamura and D. E. Fleming (Bacteriol.

Antimicrobial susceptibility testing of Francisella tularensis with a modified Mueller-Hinton broth

“…The combination which gave adequate growth of F. tularensis within 24 h was Mueller-Hinton broth supplemented with Ca2" and Mg2+ (15), 2% IsoVitaleX, 0.1% glucose, and 0.025% ferric pyrophosphate. Blood, cysteine, peptone, and glucose have been reported to be required for growth of the organism (1, 5,7,9,13,16,19,20,23). We used ferric pyrophosphate because two of these organisms were isolated or grew on charcoal-yeast extract agar (6).…”

“…In vitro susceptibility testing of F. tularensis has not been routinely or systematically performed because the bacterium is difficult to grow on conventional laboratory medium and because of the danger of laboratory workers acquiring laboratory infections. Some nutrients required for growth of the organisms tend to inactivate some antimicrobial agents (1, 5,7,23). In addition, the organism produces ammonia, which changes the pH of the medium and may result in changes in the in vitro susceptibility to some antimicrobial agents and may cause the growth in the medium to become self-limiting (23).…”

“…Some nutrients required for growth of the organisms tend to inactivate some antimicrobial agents (1, 5,7,23). In addition, the organism produces ammonia, which changes the pH of the medium and may result in changes in the in vitro susceptibility to some antimicrobial agents and may cause the growth in the medium to become self-limiting (23). This study was done to: (i) develop a medium that would support the growth of F. tularensis and would be acceptable for antimicrobial susceptibility testing, (ii) determine the susceptibility of F. tularensis to a variety of antimicrobial * Corresponding author.…”

Francisella tularensis does not manifest virulence in viable but non-culturable state

“…For growth of F. tularensis LVS in liquid, Scharer medium [16] or Chamberlain medium [17] was used. Modified Thayer‐Martin agar plates containing Gc medium base (36 g l −1 ; Difco Laboratories, Detroit, MI, USA), hemoglobin (10 g l −1 ; Difco), and IsoVitaleX (10 mg l −1 ; BBL Microbiology Systems, Cockeysville, MD, USA) were used for viable counts.…”

Francisella tularensis does not manifest virulence in viable but non-culturable state

“…For growth of F. tularensis LVS in liquid, Scharer medium [16] or Chamberlain medium [17] was used. Modi¢ed Thayer-Martin agar plates containing Gc medium base (36 g l 31 ; Difco Laboratories, Detroit, MI, USA), hemoglobin (10 g l 31 ; Difco), and IsoVitaleX (10 mg l 31 ; BBL Microbiology Systems, Cockeysville, MD, USA) were used for viable counts.…”