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Group B streptococci (GBS) are pathogens of both neonates and adults, with serotype III strains in particular being associated with invasive disease and meningitis. In this study, a novel GBS surface antigen, e, was found to be co-expressed with the previously reported d antigen on an identical subset of serotype III GBS. Expression of d/e on the surface of serotype III GBS was shown to distinguish the restriction digest pattern (RDP) III-3 and multilocus sequence typing (ST)-17 lineage. e-Specific antibodies were reactive with a unique, high-molecular-mass, serine-rich repeat protein (Srr-2) found exclusively in RDP III-3 strains. The gene encoding Srr-2 was located within a putative accessory secretory locus that included secY2 and secA2 homologues and had a genetic organization similar to that of the secY2/A2 locus of staphylococci. In contrast, serotype III d/e-negative strains and strains representative of serotypes Ia, Ib, Ic and II shared a common Srr-encoding gene, srr-1, and an organization of the secY2/A2 locus similar to that of previously reported serotype Ic, d/e-negative serotype III and serotype V GBS strains. Representative serotype III d/e-positive strains had LD 90 values 3-4 logs less than those of serotype III d/e-negative strains in a neonatal mouse model of infection. These results indicate that the RDP III-3/ST-17 lineage expresses Srr-2 and is highly virulent in an in vivo model of neonatal sepsis.

ABSTRACT. Objective. Haemophilus influenzae type b causes severe disease in nonimmune infants and young children; other serotypes are uncommon pathogens and thought to have low virulence. Some have hypothesized that with the virtual elimination of H influenzae type b, other serotypes might acquire virulence traits and emerge as important pathogens of children. We describe the clinical, epidemiologic, and molecular biologic features of 5 cases of severe disease attributable to Haemophilus influenzae type a.Methods. After observing 4 cases of invasive disease caused by H influenzae type a, we reviewed microbiology records at 3 reference laboratories that perform all serotyping in Utah and surveillance databases. Strains of H influenzae type a and control strains were examined by Southern blotting with the use of the cap probe pUO38 and by pulsed-field gel electrophoresis. The putative virulence mutation, the IS1016-bexA deletion, was detected by polymerase chain reaction amplification and sequencing.Results. During a 10-month period, we observed 5 children with severe invasive disease caused by H influenzae type a. No isolates of H influenzae type a had been submitted to the reference laboratories between 1992 and 1998. The median age of patients was 12 months (range: 6 -48 months). Four of 5 had meningitis and bacteremia; 1 had purpura fulminans. Three isolates, representing 1 of 2 pulsed-field gel electrophoresis patterns, contained the IS1016-bexA deletion and were associated with particularly severe disease.Conclusions. We describe an unusual cluster of severe disease caused by H influenzae type a that resembles the clinical and epidemiologic features of H influenzae type b disease. Our data support the hypothesis that the IS1016-bexA deletion may identify more virulent strains of H influenzae. Pediatrics 2001;108(1). URL: http://www. pediatrics.org/cgi/content/full/108/1/e18; Haemophilus influenzae, epidemiology, virulence, serotyping, pathogenicity.

Type III group B streptococci (GBS) isolated from Tokyo and Salt Lake City were classified according to the similarity of HindIII and Sse83871 restriction digest patterns (RDPs) of bacterial DNA. The bacteria were clustered into three RDP types, with excellent correlation between subtyping based on the two enzymes. The majority (91%) of invasive isolates obtained from neonates were RDP type III-3. The mean sialic acid content of the III-3 strains was higher than that of other type III strains. Closely related isolates were concordant for expression of the bacterial enzyme C5a-ase, but invasive strains were no more likely to be C5a-ase positive than were strains isolated from the genitourinary tract of pregnant women. These data indicate that a group of genetically related organisms with increased capsule production causes the majority of invasive type III GBS disease. Group B streptococci (GBS) 3) causes most serotype III neonatal sepsis, suggesting the RDP typing. DNA was extracted from GBS suspended in agarose existence of a genetically related subgroup of serotype III GBS gel plugs (InCert; FMC BioProducts, Rockland, ME) according to that are intrinsically more virulent than other serotype III strains the manufacturer's instructions except that mutanolysin and SDS con- [4]. The purpose of these studies was to determine whether taining proteinase K were used for digestion of the bacteria. DNA in invasive serotype III isolates from Salt Lake City, as well as the agarose gel plugs was digested with HindIII, extracted from the more recently isolated clinical isolates from Japan, are also agarose with phenol, and redigested with HindIII. The DNA sample RDP III-3. We also validated the HindIII typing by typing the was then subjected to electrophoresis in a conventional ethidium bromide-agarose gel. The similarity between densitometric RDPs from individual strains was expressed as a Pearson product moment correlation coefficient (PPMCC) and clustered by the unweighted

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Nontypeable Haemophilus influenzae (NTHI) is an important respiratory pathogen. NTHI initiates infection by adhering to the airway epithelium. Here, we report that NTHI interacts with intracellular adhesion molecule 1 (ICAM-1) expressed by respiratory epithelial cells. A fourfold-higher number of NTHI bacteria adhered to Chinese hamster ovary (CHO) cells transfected with human ICAM-1 (CHO-ICAM-1) than to control CHO cells (P < 0.005). Blocking cell surface ICAM-1 with specific antibody reduced the adhesion of NTHI to A549 respiratory epithelial cells by 37% (P ‫؍‬ 0.001) and to CHO-ICAM-1 cells by 69% (P ‫؍‬ 0.005). Preincubating the bacteria with recombinant ICAM-1 reduced adhesion by 69% (P ‫؍‬ 0.003). The adherence to CHO-ICAM-1 cells of NTHI strains deficient in the adhesins P5, P2, HMW1/2, and Hap or expressing a truncated lipooligosaccharide was compared to that of parental strains. Only strain 1128f ؊ , which lacks the outer membrane protein (OMP) P5-homologous adhesin (P5 fimbriae), adhered less well than its parental strain. The numbers of NTHI cells adhering to CHO-ICAM-1 cells were reduced by 67% (P ‫؍‬ 0.009) following preincubation with anti-P5 antisera. Furthermore, recombinant ICAM bound to an OMP preparation from strain 1128f ؉ , which expresses P5, but not to that from its P5-deficient mutant, confirming a specific interaction between ICAM-1 and P5 fimbriae. Incubation of respiratory epithelial cells with NTHI increased ICAM-1 expression fourfold (P ‫؍‬ 0.001). Adhesion of NTHI to the respiratory epithelium, therefore, upregulates the expression of its own receptor. Blocking interactions between NTHI P5 fimbriae and ICAM-1 may reduce respiratory colonization by NTHI and limit the frequency and severity of NTHI infection.Nontypeable Haemophilus influenzae (NTHI) is a gram-negative nonencapsulated coccobacillus. It is the most frequent cause of bacterial exacerbations of chronic obstructive pulmonary disease; a major cause of acute otitis media, sinusitis, and bronchitis; and an occasional cause of serious invasive infections, such as bacteremia and meningitis. Adhesion of NTHI to the respiratory epithelium promotes colonization and subsequent epithelial and endothelial invasion by the bacteria. NTHI binds specifically to a variety of receptors on the host cell membrane, including carcinoembryonic antigen cell adhesion molecule 1 (CEACAM1) and CEACAM3, platelet-activating factor receptor, fibronectin, laminin, and respiratory epithelial mucins (10,14,18,31,42). The importance of NTHI interaction with each of these receptors during human colonization and infection, however, is not yet well understood.Intercellular adhesion molecule 1 (ICAM-1; CD54) is a member of the immunoglobulin (Ig)-like superfamily that contains five Ig domains, a transmembrane domain, and a short cytoplasmic tail (30). ICAM-1 makes possible reversible adhesion and signal transduction between cells, processes critical to normal leukocyte recruitment and to T-cell development, by interacting with specific receptors. As is the c...

To examine the human antibody repertoire generated against a biologically significant antigen we Invest. 1993Invest. .91:2734Invest. -2743

The immune repertoire to Haemophilus influenzae type b capsular polysaccharide (Hib PS)