API QuadFERM+ with rapid DNase for identification of Neisseria spp. and Branhamella catarrhalis

Abstract

The QuadFERM+ system (Analytab Products, Plainview, N.Y.), a 2-h carbohydrate degradation method for the identification of Neisseria spp., was evaluated along with a rapid DNase test for confirmation of Branhamella catarrhalis. QuadFERM+ identified 100% of 82 N. gonorrhoeae and 96% of 54 N. meningitidis strains. The two misidentified meningococcal strains were biochemically atypical and were also misidentified by the conventional method. Of 26 N. lactamica strains, 25 (96%) were correctly identified. Of 21 Neisseria spp., 14 (67%) produced carbohydrate reactions in agreement with the conventional procedure, and 7 strains produced detectable acid in the QuadFERM + from maltose and sucrose but not glucose. All 9 N. cinerea and 30 B. catarrhalis strains were asaccharolytic by QuadFERM+. The rapid DNase test was positive for all B. catarrhalis strains and negative for all other organisms. Two beta-lactamase-positive N. gonorrhoeae strains and 25 (93%) of 27 beta-lactamase-positive B. catarrhalis strains were detected by the 2-h acidometric beta-lactamase test on the strip. QuadFERM+ with rapid DNase is a simple and easily interpretable method for identification of these organisms in the clinical laboratory.

Branhamella catarrhalis: an organism gaining respect as a pathogen.

“…The potentially confusing coccobacillary cells of Moraxella and Acinetobacter species elongate into snakelike cells when division is blocked by sublethal concentrations of penicillins or certain other antibacterial agents. Since elongation does not occur with B. catarrhalis or Neisseria species, this is an easy way to distinguish them from nonsaccharolytic, short paired rods (63 155,185), Gonobio-Test (94), and API QuadFERM+ (109,156). Minitek test reactions were correct in some instances (94), but not all (233).…”

“…The results obtained with these methods are not equally reliable (101,156,234). For example, one B. catarrhalis strain that produces a low level of P-lactamase was sent to laboratories as part of the 1983 proficiency survey by the College of American Pathologists.…”

Historical perspectives and identification of Neisseria and related species.

“…Commensal Neisseria spp. rarely grow on media selective for the gonococcus (55,59). Thus, the oropharyngeal carriage rate of the colistin-susceptible commensal species must be determined on a colistin-free medium.…”

“…The prevalence of some species may vary geographically, however. Strains of colistin-resistant N. subflava biovar perflava have been isolated repeatedly in Chicago (54,55) and infrequently in DeKalb County (60) but not in Seattle (59). In contrast, K. denitrificans strains were isolated from 16% of patients in DeKalb County 60 (95).…”

“…subflava biovar perfiava and B. catarrhalis are colistin resistant and also grow on this medium (33,54,55). It should be noted at the same time, however, that some strains of N. gonorrhoeae may not be isolated on selective media if they are vancomycin susceptible (71); chocolate agar or media containing lower concentrations of vancomycin must be used to isolate these strains.…”