Differentiation of Kingella denitrificans from Neisseria gonorrhoeae by growth on a semisolid medium and sensitivity to amylase

Odugbemi, T; Arko, R J

doi:10.1128/jcm.17.2.389-391.1983

Cited by 8 publications

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1. The results with purified human amylase thus confirmed previous reports of the effects of saliva and crude pancreatic amylase on the growth of N. gonorrhoeae (9). Amylase disks applied to GC agar plates without organ-isms produced clear zones (25to 30-mm diameter) in the agar, whereas heat-inactivated amylase or buffer did not.…”

Section: Resultssupporting

confidence: 88%

Amylase inhibits Neisseria gonorrhoeae by degrading starch in the growth medium

Gregory¹,

Gregory²,

Bruns³

et al. 1983

J Clin Microbiol

View full text Add to dashboard Cite

Highly purified salivary a-amylase inhibited the growth of fresh isolates of Neisseria gonorrhoeae on GC agar base medium supplemented with 2% IsoVitaleX (BBL Microbiology Systems). Hydrolysis of starch in the medium by amylase resulted in a negative starch-iodine test. However, purified amylase did not inhibit gonococcal growth on agar plates that contained hemoglobin (chocolate agar). This effect was not caused by inhibition of amylase, since amylase activity was the same in the presence or absence of blood products. Moreover, survival of N. gonorrhoeae in buffered saline was not affected by amylase. These results suggest that amylase inhibited the growth of N. gonorrhoeae on GC agar base plates by hydrolyzing starch. Recent reports (6, 9) have suggested that amylase inhibits the growth of Neisseria gonorrhoeae. This conclusion has been based on the finding that crude pancreatic ot-amylase and whole saliva inhibit the growth of N. gonorrhoeae in liquid medium and on some semisolid media. If amylase does have direct antigonococcal activity, this might predict a natural barrier to gonococcal infection at anatomic sites rich in amylase, e.g., the oral cavity. Alternatively, the observed effect may be due to in vitro test conditions. An earlier communication (9) showed that blood products in chocolate agar plates interfered with the inhibitory effect of amylase. The mechanism of this latter finding is unclear because blood does not usually contain amylase inhibitors (2). Previous studies of amylase inhibition of N. gonorrhoeae were performed with impure preparations of amylase, so we reexamined this phenomenon by using highly purified human salivary ot-amylase to eliminate possible effects due to impurities in the enzyme preparation. Our results suggest that ot-amylase inhibits growth of fresh isolates of N. gonorrhoeae by degrading starch in the growth medium but has no direct effect on the survival of the gonococcal organisms themselves. Since both starch and blood products are known to protect N. gonorrhoeae from inhibitory factors (3), gonococcal growth on chocolate agar plates in the presence of otamylase appears to be attributable to the ability of blood to substitute for starch as a scavenger of growth inhibitors.

show abstract

Section: Resultssupporting

confidence: 88%

Amylase inhibits Neisseria gonorrhoeae by degrading starch in the growth medium

Gregory¹,

Gregory²,

Bruns³

et al. 1983

J Clin Microbiol

View full text Add to dashboard Cite

show abstract

“…It appears that the inhibitory effects produced by exposing media to amylase result from the degradation of starch, which otherwise provides a detoxifying effect by neutralizing fatty acids and possibly other inhibitors in the medium. Serum and other blood products (hemoglobin) may have similar detoxifying effects and can interfere with the effects produced by amylase (8). In this study, translucent, hemoglobin-free medium was used exclusively for performing the amylase test.…”

Section: N Gonorrhoeae Incubated For 72 H and Showing Positivementioning

confidence: 99%

Superoxol and amylase inhibition tests for distinguishing gonococcal and nongonococcal cultures growing on selective media

Arko¹,

Odugbemi²

1984

J Clin Microbiol

Self Cite

View full text Add to dashboard Cite

Two inexpensive screening tests were evaluated singly and in tandem for distinguishing Neisseria gonorrhoeae from other oxidase-positive microorganisms growing on selective gonococcal media. In tests of 728 cultures, including 460 N. gonorrhoeae, 4 Neisseria lactamica, 257 Neisseria meningitidis, and 7 Branhamella catarrhalis, both Superoxol (30% H202; J. T. Baker Chemical Co., Phillipsburg, N.J.) and amylase inhibition tests were 100% sensitive (positive) for 20-h cultures of N. gonorrhoeae. Singly, the Superoxol test was 92.7% specific for N. gonorrhoeae, compared with a specificity of 82.3% for the amylase inhibition test. By using tandem screening tests to distinguish gonococci, we achieved an overall specificity of 98.6%. Group A meningococci were the primary source of error in the Superoxol test, with 97% (37 of 38) strains producing gonococcal like reactions for catalase. From 5 to 20% of N. meningitidis serogroups X, Y, Z, and Z' and nontypable strains, as well as about 50% of B. catarrhalis and N. lactamica strains, were also strong catalase producers.

show abstract