Comparative laboratory evaluation of three antigen detection methods for diagnosis of Haemophilus influenzae type b disease

Abstract

Cerebrospinal fluid, urine, serum, and other body fluid specimens from pediatric patients with systemic disease were tested with Bactigen latex agglutination (555 specimens), Phadebact coagglutination (319 specimens), and counterimmunoelectrophoresis (335 specimens) for the presence of Haemophilus influenzae type b antigen. All three methods showed good sensitivity for detecting antigen in the cerebrospinal fluid of patients with culture-positive meningitis (-86% sensitivity). However, coagglutination and counterimmunoelectrophoresis were much less sensitive (c40%) than latex agglutination (96%) for detecting antigen in other body fluid specimens in culture-positive, nonmeningeal H. influenzae disease. Bactigen latex agglutination was also more sensitive than the other procedures for detecting antigen in specimens from patients with culture-negative, presumed H. influenzae disease. Comparative testing of fluids spiked with known quantities of purified H. influenzae b polyribosephosphate capsular polysaccharide revealed an apparent 100-fold greater sensitivity with Bactigen as compared with the other two methods. Although all three methods showed good specificity (>98%), both agglutination methods gave a few false-positive results. In a clinical setting where both meningeal and nonmeningeal H. influenzae b disease are encountered frequently, Bactigen latex agglutination appears to be superior to coagglutination and counterimmunoelectrophoresis for detecting antigen in body fluids.

Haemophilus Influenzae Type B Meningitis Among Children in Hanoi, Vietnam: Epidemiologic Patterns and Estimates of H. Influenzae Type B Disease Burden

“…This finding may be due to a number of factors, including the reported lower sensitivity (86%) of latex agglutination antigen detection relative to bacterial culture. 34,35 One study suggested that Hib latex agglutination may require Ն 1,000 bacteria/mL of CSF to yield a positive test result. 36 The present study provides evidence from populationbased surveillance that Hib is the most common cause of bacterial meningitis among Vietnamese children living in urban and rural settings with high incidence rates observed in children < 24 months of age.…”

Rapid bacterial antigen detection is not clinically useful

“…The LA kits, which have replaced counterimmune electrophoresis, are in many ways ideal assays. They have the potential advantages of being rapid, technologically straightforward, specific, sensitive for detection of nanogram quantities of antigen, and positive despite prior antimicrobial therapy (1,2,8,9,10,13,16,20,30,37,39,41,42,45). Additionally, urine can be used as the sample material, with the advantage that it is simple to collect and contains bacterial antigens concentrated 10-to 50-fold over those found in serum (1).…”

“…Several factors, however, limit the clinical utility of bacterial antigen tests and make their routine use controversial. These factors include a decline in the incidence of Hib invasive disease following the advent of specific vaccination (35), imperfect antigen specificity (4,6,8,11,13,21,23,25,28,30,32), misleading positive results due to detection in urine or CSF of circulating Hib antigen after vaccination (7,15,36,43,44), contamination of urine with skin flora (3,40), and, importantly, the common failure of physicians to respond to rapidly generated diagnostic test results (26). In this review of over 5,000 LA tests, we found no evidence of clinical utility to support their current common use and instead found a high incidence of confounding results.…”

Comparison of a new, rapid enzyme-linked immunosorbent assay with latex particle agglutination for the detection of Haemophilus influenzae type b infections

“…Emphasis has been placed on the sensitivity of these tests, since failure to treat haemophilus infection promptly could have disastrous consequences. Thus, tests such as counterimmunoelectrophoresis, which cannot detect the low concentrations of PRP present in some invasive H. influenzae type b infections (1,5,(9)(10)(11), have largely been abandoned in favor of more sensitive tests, such as latex particle agglutination (LPA). LPA can detect 1 ng or less of PRP per ml in clinical specimens and has been found to identify nearly all culture-documented haemophilus infections (3,(8)(9)(10)(11)(12).…”