Multicenter Evaluation of the New Vitek 2 Neisseria - Haemophilus Identification Card

Abstract

The new Neisseria-Haemophilus identification (NH) card for Vitek 2 was compared with 16S rRNA gene sequencing (16S) as the reference method for accurate identification of Neisseria spp., Haemophilus spp., and other fastidious gram-negative bacteria. Testing was performed on the Vitek 2 XL system with modified software at three clinical trial laboratories. Reproducibility was determined with nine ATCC quality control strains tested 20 times over a minimum of 10 days at all three sites. A challenge set of 30 strains with known identifications and 371 recent fresh and frozen clinical isolates were also tested. Expected positive and negative biochemical reactions were also evaluated for substrate reproducibility. All microorganisms were tested on the NH card, and all clinical and stock isolates were saved for 16S testing. All reproducibility tests yielded expected results within a 95% confidence interval. For challenge microorganisms, there was 98% overall correct identification, including 8% low discrimination, 2% incorrect identification, and 0% unidentified. For clinical strains, there was 96.5% overall correct identification, including 10.2% low discrimination, 2.7% incorrect identification, and 0.8% unidentified. The 2.7% (10/371) of clinical isolates that gave an incorrect identification consisted of 7 isolates correct to genus and 3 strains incorrect to genus. There were an additional 27 strains (primarily Neisseria species) for which the 16S identification result was different from the NH card result. These were all unclaimed species by the system. The new NH card met all performance criteria within a 95% confidence interval compared to identification of clinical isolates by 16S.In the diagnostic clinical microbiology laboratory, rapid and accurate identification of bacterial pathogens is essential for prompt and appropriate management of infected patients. This is important for bacterial pathogens within the genera Haemophilus and Neisseria.The science has evolved over many years. Classical methods gave way to substrate-based identification of these microorganisms involving overnight and then shorter incubation. More recently molecularly based identification has started to change the landscape (2,5,7,8,12), but for most laboratories that lack such sophisticated technical capabilities, the ability to use either a manual or automated system that will give a high level of correct identifications is sufficient for most purposes.For identification of Haemophilus and Neisseria species, a variety of commercial methods have been available on the market for many years. For Neisseria species these have included Neisseria-Kwik, Gonogen, Gonochek II, RIM-N, API QuadFERM-Plus, Minitek, Identicult-Neisseria, and several others (1,6,16,18). All of these are based on colorimetric changes in miniaturized substrates, with either enzymatic or growth end points. The ability to identify and separate Haemophilus species from nonpathogenic Neisseria species, particularly those from the respiratory tract, then led to the addition ...

Prevalence of Thermotolerant Campylobacter spp. in Chicken Meat in Croatia and Multilocus Sequence Typing of a Small Subset of Campylobacter jejuni and Campylobacter coli Isolates

“…Namely, these cultures are recommended to be readily submitt ed to biochemical testing upon exposure to aerobic atmosphere. During clinical strain testing by the VITEK2 system, Rennie et al (29) reported the 96.5 % rate of correct identifi cation, including 10.2 % of low discrimination of strains of undeterminable species diff erence, 2.7 % of incorrect identifi cation and 0.8 % of the results classifi ed as unidentifi ed, which is con sistent with our study. Thermotolerant bacteria of the genus Campylobacter were identifi ed in 100 % of cases by the PCR/REA method, whereby identifi cation at the species level failed in 14 (7.87 %) isolates (positive PCR, negative REA).…”

Classification, Identification, and Clinical Significance of Haemophilus and Aggregatibacter Species with Host Specificity for Humans

“…Phenotypic characteristics can be determined by conventional testing in single tubes (15,28,48,130) or by a number of semi-or fully automated systems (129,(131)(132)(133)(134)(135)(136)(137). The use of automated systems is feasible and cost-effective, and they usually perform well when challenged with strains of species that are included in their databases (135)(136)(137).…”

“…The use of automated systems is feasible and cost-effective, and they usually perform well when challenged with strains of species that are included in their databases (135)(136)(137). However, attempts to identify species that are not included in the identification database may lead to misidentifications (14,138), which is highly unsatisfactory.…”

Difficult identification ofHaemophilus influenzae, a typical cause of upper respiratory tract infections, in the microbiological diagnostic routine

“…Biochemical assays have been shown to lack reliability [6,17,[20][21][22][23][24][25][26][27][28]. Complex multiplex PCR-approaches [38] or sequence-based approaches [5] are hardly realistic for the routine setting because such procedures are both expensive and demanding regarding hands-on time of technical laboratory assistants.…”

“…As recently shown, traditional differentiation systems for the identifi cation of Haemophilus spp. like api-NH (bioMérieux, Nürtingen, Germany) or VITEK-NH cards (bioMérieux) show misidentifi cations in 1-10% of the samples [21,[26][27][28].…”