Cross-reaction of spontaneous capsule-deficientHaemophilus influenzae type b mutants with type-specific antisera

Falla, Timothy J.; Anderson, E. C.; Chappell, M. M.; Slack, Mary P. E.; Crook, D

doi:10.1007/bf01967598

Cited by 9 publications

(7 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is possibly a typical example of the difficulties of identifying capsular types with serological methods (26, 27), but there is an alternative explanation. Some years ago, Falla and co‐workers described a phenomenon observed among spontaneous capsule‐deficient type b strains: they cross‐reacted with type b and c type‐specific antisera (28). The most frequent cross‐reaction was also with the type c‐specific antiserum in the present study.…”

Section: Discussionmentioning

confidence: 99%

Nontypeable Haemophilus influenzae strains with the capsule‐associated insertion element IS1016 may mimic encapsulated strains

Karlsson

Melhus

2006

APMIS

View full text Add to dashboard Cite

With the elimination of Haemophilus influenzae type b through vaccination, it has been suggested that other types of H. influenzae strains might acquire virulence traits and emerge as important pathogens. The gene sequence IS1016 has been associated with an increased capacity to cause severe infections. It is usually present in encapsulated strains but is sometimes harbored by nontypeable H. influenzae strains. To explore this further, 118 H. influenzae isolates, collected from both patients and healthy carriers, were investigated with PCR with reference to this gene sequence. Isolates positive for the insertion element were bio- and serotyped. The presence of hmw genes for adherence, the genetic profile, and the ability to form biofilm in vitro were investigated. A total of 15 isolates were IS1016-positive, whereof 12 were nontypeable. All 12 nontypeable isolates were obtained from healthy carriers, and 92% of the isolates were biotype I. They cross-reacted to some extent with type-specific antisera or exhibited a restricted genetic diversity like encapsulated strains. Furthermore, they lacked hmw-genes, and their ability to form biofilms was comparable with a capsule-deficient type b strain. Although this subset of strains mimicked traits usually exhibited by encapsulated strains, the isolation frequency did not seem to have been affected by vaccination.

show abstract

Section: Discussionmentioning

confidence: 99%

Nontypeable Haemophilus influenzae strains with the capsule‐associated insertion element IS1016 may mimic encapsulated strains

Karlsson

Melhus

2006

APMIS

View full text Add to dashboard Cite

show abstract

“…As a result public health laboratories have sought to serotype H. influenzae isolated from normally sterile sites (Satola et al , 2007). Comparison of the commercially available slide agglutination to genetic methods identifying the genes involved in the synthesis and export of the capsular polysaccharides had revealed both false-positive and false-negative agglutination reactions (Bokermann et al , 2003; Falla et al , 1993; LaClaire et al , 2003; Sam et al , 2005; Satola et al , 2007). …”

Section: Introductionmentioning

confidence: 99%

Determination of capsulation status in Haemophilus influenzae by multiplex polymerase chain reaction

Nelson

Smith

2010

Diagnostic Microbiology and Infectious Disease

View full text Add to dashboard Cite

Since the introduction of H. influenzae type b conjugate vaccines there have been concerns regarding the emergence of invasive non-type b strains. Serotyping of H. influenzae with commercially available reagents is subjective. Definitive characterization of the capsulation status can be performed by PCR amplification of capsular genes. However, PCR amplification of the conserved export locus in the two known phylogenic lines of type b strains, and detection of serotype conferring genes in each of the six serotypes requires multiple assays. To rapidly screen multiple isolates, we devised a multiplex method using 15 primers which produced a serotype-specific, distinct pattern of amplicons with reference encapsulated H. influenzae. We applied this technique to a panel of 35 clinical isolates which had been serotyped as type a, c, d, e or f by slide agglutination; 15 strains lacked capsular genes. Conversely, of 69 invasive isolates which were not serotypeable, all but 11 contained capsule genes. We conclude that this technique will be useful in screening recently isolated H. influenzae for capsulation status.

show abstract

“…The method most widely used for identifying the capsule serotype of H. influenzae is slide agglutination (SlAg) with polyclonal sera. However, misidentifications of H. influenzae serotypes by this method have been reported (7,22,27) and recently have become a matter of concern (13), attributed to the performance of the assay and difficulties in the interpretation of SlAg reactions. A short time ago, preliminary results during surveillance for H. influenzae from the nasopharynx in a vaccinated population in Brazil showed a high rate of serotype b among colonizing (Col) H. influenzae isolates.…”

mentioning

confidence: 99%

Evaluation of Methodology for Serotyping Invasive and Nasopharyngeal Isolates of Haemophilus influenzae in the Ongoing Surveillance in Brazil

et al. 2003

View full text Add to dashboard Cite

To assess the magnitude of discrepant results obtained by routine Haemophilus influenzae serotyping, 258 isolates, collected by the epidemiological surveillance system in Brazil from individuals with invasive diseases or carriage, were evaluated by two slide agglutination (SlAg) methods: SlAg method 1, by which strains were initially screened with a serotype b-specific antiserum, and SlAg method 2, by which strains were tested against all serotype-specific antisera in parallel. Investigators comparing results of the two SlAg methods with those obtained by capsule type-specific PCR were blinded to the method used. The serotype prevalence rates found by the three methods were significantly different, involving discrepancies mainly between serotype b and noncapsulated (NC) isolates. For invasive isolates (n ‫؍‬ 131), the overall agreement rate between SlAg method 1 or 2 and PCR was 68.0 or 88.3%, respectively, whereas for colonizing isolates (n ‫؍‬ 127) the corresponding rate was 46.5 or 94.2%, respectively. SlAg method 2 improved the ascertainment of serotypes over that obtained with SlAg method 1, demonstrating good correlation with PCR. Use of the polyvalent antiserum as a screening reagent for SlAg for invasive and colonizing isolates showed poor discriminatory power, with a sensitivity of 65.8% and a specificity of 91.7%. We stress the importance of using a well-standardized SlAg methodology and suggest that reference laboratories should utilize PCR routinely to confirm SlAg results and to check all nonspecific SlAg reactions and apparent NC isolates by SlAg in order to provide reliable data on the prevalence of H. influenzae serotypes in the H. influenzae type b vaccine era.

show abstract

Cross-reaction of spontaneous capsule-deficientHaemophilus influenzae type b mutants with type-specific antisera

Cited by 9 publications

References 9 publications

Nontypeable Haemophilus influenzae strains with the capsule‐associated insertion element IS1016 may mimic encapsulated strains

Nontypeable Haemophilus influenzae strains with the capsule‐associated insertion element IS1016 may mimic encapsulated strains

Determination of capsulation status in Haemophilus influenzae by multiplex polymerase chain reaction

Evaluation of Methodology for Serotyping Invasive and Nasopharyngeal Isolates of Haemophilus influenzae in the Ongoing Surveillance in Brazil

Contact Info

Product

Resources

About