Biochemical characteristics of 130 recent isolates from Haemophilus influenzae meningitis

Characterization of Serotypes and Molecular Drug Resistance Patterns of Haemophilus influenzae in Kunming Children

The present study aimed to determine the capsular serotype distribution and antimicrobial drug resistance patterns of Haemophilus influenzae from children in the Kunming region of China. This information could guide policymakers in clinical treatment. In the present study, H. influenzae isolates were tested for their serotypes, antimicrobial susceptibility pattern, and presence of β-lactamases. One-hundred forty-eight H. influenzae strains isolated from children 0-2 years old were investigated for capsular types by glass slide agglutination and molecular methods, and biotyped by the biochemical reactions. The drug resistance-encoding genes TEM-1, ROB-1, and the ftsI gene mutations PBP3-3, and PBP3-BLN were detected with real-time quantitative polymerase chain reaction (qPCR). The prevalence of β-lactamase-producing strains (60.3%) was significantly higher (p < 0.05) than non-enzyme-producing strains. β-Lactamase-producing strains were multidrug resistant to various antibiotics such as ampicillin, tetracycline, sulfamethoxazole/trimethoprim, chloramphenicol, cefuroxime, and cefaclor. Among β-lactamase-producing strains, the detection rates of the TEM-1, PBP3-BLN, PBP3-s, and ROB-1 were 54.1%, 18.9%, 11.8%, and 6.9%, respectively. The biotyping results show that most H. influenzae strains were of type II and III. Non-typeable H. influenzae (NTHi) accounted for 89.3% of the strains. NTHi strains were the most prevalent in this region; most belonged to biological types II and III. β-Lactamase-positive ampi-cillin-resistant (BLPAR) strains were prevalent among H. influenzae isolates in this region.

Evaluation of molecular typing for national surveillance of invasive clinical Haemophilus influenzae isolates from Denmark

Haemophilus influenzae is a gram-negative coccobacillus known to cause respiratory and invasive infections. It can possess a polysaccharide capsule that can be categorized into six different serotypes (i.e., Hia, Hib, Hic, Hid, Hie, and Hif) and non-encapsulated strains that are defined as non-typeable. Furthermore, H. influenzae can be characterized into eight biotypes (I-VIII). Traditionally, isolates have been serotyped and biotyped using phenotypic methods; however, these methods are not always reliable. In this study, we evaluate the use of whole-genome sequencing (WGS) for national surveillance and characterization of clinical Danish H. influenzae isolates. In Denmark, all clinical invasive isolates between 2014 and 2021 have been serotyped using a traditional phenotypic latex agglutination test as well as in silico serotyped using the in silico programs "hinfluenzae_capsule_characterization" and "hicap" to compare the subsequent serotypes. Moreover, isolates were also biotyped using a phenotypic enzyme test and the genomic data for the detection of the genes encoding ornithine, tryptophan, and urease. The results showed a 99-100% concordance between the two genotypic approaches and the phenotypic serotyping, respectively. The biotyping showed a 95% concordance between genotyping and phenotyping. In conclusion, our results show that in a clinical surveillance setting, in silico serotyping and WGS-based biotyping are a robust and reliable approach for typing clinical H. influenzae isolates.

A ZnO–CNT nanocomposite based electrochemical DNA biosensor for meningitis detection

The article focuses on the synthesis of ZnO and CNTs based electrochemical DNA biosensor and its application towards meningitis DNA detection with high sensitivity as well as selectivity.

Classification, identification, and clinical significance of Haemophilus and Aggregatibacter species with host specificity for humans

The aim of this review is to provide a comprehensive update on the current classification and identification of Haemophilus and Aggregatibacter species with exclusive or predominant host specificity for humans. Haemophilus influenzae and some of the other Haemophilus species are commonly encountered in the clinical microbiology laboratory and demonstrate a wide range of pathogenicity, from life-threatening invasive disease to respiratory infections to a nonpathogenic, commensal lifestyle. New species of Haemophilus have been described (Haemophilus pittmaniae and Haemophilus sputorum), and the new genus Aggregatibacter was created to accommodate some former Haemophilus and Actinobacillus species (Aggregatibacter aphrophilus, Aggregatibacter segnis, and Aggregatibacter actinomycetemcomitans). Aggregatibacter species are now a dominant etiology of infective endocarditis caused by fastidious organisms (HACEK endocarditis), and A. aphrophilus has emerged as an important cause of brain abscesses. Correct identification of Haemophilus and Aggregatibacter species based on phenotypic characterization can be challenging. It has become clear that 15 to 20% of presumptive H. influenzae isolates from the respiratory tracts of healthy individuals do not belong to this species but represent nonhemolytic variants of Haemophilus haemolyticus. Due to the limited pathogenicity of H. haemolyticus, the proportion of misidentified strains may be lower in clinical samples, but even among invasive strains, a misidentification rate of 0.5 to 2% can be found. Several methods have been investigated for differentiation of H. influenzae from its less pathogenic relatives, but a simple method for reliable discrimination is not available. With the implementation of identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry, the more rarely encountered species of Haemophilus and Aggregatibacter will increasingly be identified in clinical microbiology practice. However, identification of some strains will still be problematic, necessitating DNA sequencing of multiple housekeeping gene fragments or full-length 16S rRNA genes.

Haemophilus influenzae serotype a as a cause of serious invasive infections

Haemophilus influenzae, particularly H influenzae serotype b (Hib), is an important pathogen that causes serious diseases like meningitis and septicaemia. Since the introduction of Hib conjugate vaccines in the 1990s, the epidemiology of invasive H influenzae disease has changed substantially, with most infections now caused by non-Hib strains. We discuss the importance of H influenzae serotype a (Hia) as a cause of serious morbidity and mortality and its global epidemiology, clinical presentation, microbiology, immunology, prevention, and control. Much like Hib, the capsule of Hia is an important virulence factor contributing to the development of invasive disease. Molecular typing of Hia has identified distinct clonal groups, with some linked to severe disease and high case-fatality rates. Similarities between Hia and Hib capsules, their clinical presentation, and immunology of infection suggest that a bivalent Hia-Hib capsular polysaccharide-protein conjugate vaccine could offer protection against these two important serotypes of H influenzae.

Haemophilus influenzae as an airborne contamination in child day care centers

BACKGROUND

The aim of this study was to assess the exposure of children to airborne Haemophilus influenzae in day care centers.

METHODS

Air samples were taken using an Andersen impactor in 32 rooms designed for children stay. The concentrations of airborne bacteria were calculated as colony forming units (CFU) (growing on trypticase soy agar) per cubic meter of air (CFU/m(3)). The compositions of bioaerosol were determined on blood trypticase soy agar and Haemophilus selective agar. Isolated strains were identified using API NH strips and apiweb software. The antibiotic resistance of H influenzae strains was determined by the disk diffusion method.

RESULTS

Compared with the proposed criteria for microbiologic quality of indoor air, the rooms were characterized by the very high bacterial contamination of the air. The prevailing component of bacterial aerosol was gram-positive cocci. Airborne H influenzae strains were found in 25% of the investigated rooms and were mostly classified as biotype II (33%).

CONCLUSION

It may be accepted that the exposure to airborne H influenzae is typical of child day care centers in contrast to indoor environments with older population. Child day care center contribute to the expansion of H influenzae in human population via air. Generally, airborne H influenzae isolates from the investigated child day care centers were susceptible to older antibiotics such as ampicillin and amoxicillin-clavulanic acid.

Molecular typing methods for outbreak detection and surveillance of invasive disease caused by Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae, a review

Invasive disease caused by the encapsulated bacteria Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae remains an important cause of morbidity and mortality worldwide, despite the introduction of successful conjugate polysaccharide vaccines that target disease-associated strains. In addition, resistance, or more accurately reduced susceptibility, to therapeutic antibiotics is spreading in populations of these organisms. There is therefore a continuing requirement for the surveillance of vaccine and non-vaccine antigens and antibiotic susceptibilities among isolates from invasive disease, which is only partially met by conventional methods. This need can be met with molecular and especially nucleotide sequence-based typing methods, which are fully developed in the case of N. meningitidis and which could be more widely deployed in clinical laboratories for S. pneumoniae and H. influenzae.

Association of IS1016 with the hia adhesin gene and biotypes V and I in invasive nontypeable Haemophilus influenzae

A subset of invasive nontypeable Haemophilus influenzae (NTHI) strains has evidence of IS1016, an insertion element associated with division I H. influenzae capsule serotypes. We examined IS1016-positive invasive NTHI isolates collected as part of Active Bacterial Core Surveillance within the Georgia Emerging Infections Program for the presence or absence of hmw1 and hmw2 (two related adhesin genes that are common in NTHI but absent in encapsulated H. influenzae) and hia (homologue of hsf, an encapsulated H. influenzae adhesin gene). Isolates were serotyped using slide agglutination, confirmed as NTHI strains using PCR capsule typing, and biotyped. Two hundred twenty-nine invasive NTHI isolates collected between August 1998 and December 2006 were screened for IS1016; 22/229 (9.6%) were positive. Nineteen of 201 previously identified IS1016-positive invasive NTHI isolates collected between January 1989 and July 1998 were also examined. Forty-one IS1016-positive and 56 randomly selected IS1016-negative invasive NTHI strains were examined. The hia adhesin was present in 39 of 41 (95%) IS1016-positive NTHI strains and 1 of 56 (1.8%) IS1016-negative NTHI strains tested; hmw (hmw1, hmw2, or both) was present in 50 of 56 (89%) IS1016-negative NTHI isolates but in only 5 of 41 (12%; all hmw2) IS1016-positive NTHI isolates. IS1016-positive NTHI strains were more often biotype V (P < 0.001) or biotype I (P = 0.04) than IS1016-negative NTHI strains, which were most often biotype II. Pulsed-field gel electrophoresis revealed the expected genetic diversity of NTHI with some clustering based on IS1016, hmw or hia, and biotypes. A significant association of IS1016 with biotypes V and I and the presence of hia adhesins was found among invasive NTHI. IS1016-positive NTHI strains may represent a unique subset of NTHI strains, with characteristics more closely resembling those of encapsulated H. influenzae.

Comparison of three commercial test systems for biotyping Haemophilus influenzae and Haemophilus parainfluenzae

The biotypes of Haemophilus influenzae and Haemophilus parainfluenzae isolates were determined with three commercially available biochemical test kits: the IDS RapID NH system, the Neisseria-Haemophilus identification test (NHI card), and the API NH strip. The API NH strip performed best, correctly classifying the biotypes of 371 of 380 (97.6%) different challenge strains.

High ampicillin resistance in different biotypes and serotypes of Haemophilus influenzae colonizing the nasopharynx of healthy school-going Indian children

Haemophilus influenzaeis one of the main causes of otitis media, sinusitis, meningitis, pneumonia and septicaemia in children, and the development of ampicillin resistance inH. influenzaeis a cause of serious concern. The aim of the present study was to determine the prevalence of ampicillin resistance inH. influenzaecolonizing the nasopharynx of school-going healthy North Indian children, and to compare the distribution of different biotypes and serotype b in this population. A total of 2400 school-going healthy children from 45 rural and 45 urban schools were enrolled. Nasopharyngeal swabs were collected from the children and cultured.H. influenzaewas isolated from 1001 (41·7 %) of the 2400 nasopharyngeal swabs collected. All theseH. influenzaeisolates were biotyped and serotyped, and their antibiotic susceptibility tested. All eight biotypes were present in this population. The most prevalent biotypes were I (19·6 %), II (16·8 %) and III (25·0 %). Of the 1001 isolates, 316 (31·6 %) wereH. influenzaetype b and 685 (68·4 %) were non-type bH. influenzae, and 22·9 % were resistant to ampicillin, 41·9 % to chloramphenicol, 27·5 % to erythromycin and 67·3 % to co-trimoxazole. Of the 316H. influenzaetype b isolates, 44·0 % were ampicillin resistant, while only 13·1 % non-type bH. influenzaeisolates were ampicillin resistant. Of the 229 ampicillin-resistantH. influenzaeisolates, 196 (85·6 %) were positive forβ-lactamase; 93·4 % (214/229) were biotypes I, II and III, of which 49 % were biotype I, 27·9 % were type II and 16·6 % were type III. Most of the strains belonging to biotypes III–VIII were ampicillin sensitive. Ampicillin resistance is significantly more common in biotype I and serotype b than in other biotypes and serotypes.

[Haemophilus influenzae: phenotype characteristics of strains isolated in 12 Catalan hospitals over one year]

INTRODUCTION

The purpose of this study was to investigate the antigenic and biochemical characteristics, antibiotic susceptibility, and mechanisms for acquiring resistance of Haemophilus influenzae strains isolated in several Catalan hospitals, to determine the current situation regarding this microorganism in our area.

METHODS

Serotype, biotype and betalactamase production, as well as susceptibility to eight antimicrobial agents (ampicillin, cefuroxime, cefotaxime, cefixime, clarithromycin, co-trimoxazole, chloramphenicol and ciprofloxacin) were determined in 497 H. influenzae strains isolated from 1 May 1999 to 30 April 2000 in 12 Catalan hospitals.

RESULTS

Among the total, 97.5% of strains were nontypable and 50% of the encapsulated strains were serotype b (all isolated from children under 5 years old). There was a predominance of biotype II, though no age or pathologic tropism was found among any of the biotypes. Our series confirms the previously reported trend to decreasing betalactamase mediated ampicillin resistance in our area, mainly in strains from pediatric patients. More betalactamase negative ampicillin-resistant strains (BLNAR) were isolated in children than in adults. One ciprofloxacin-resistant strain was detected.

CONCLUSIONS

Infections caused by encapsulated H. influenzae strains are infrequent in our area and the relative importance of serotype b is decreasing. Mechanisms for acquiring ampicillin resistance other than betalactamase production are emerging. Surveillance of ciprofloxacin susceptibility is required to predict therapeutic failures with this quinolone.

Limited genetic diversity of recent invasive isolates of non-serotype b encapsulated Haemophilus influenzae

Invasive infections caused by non-type b encapsulated Haemophilus influenzae have increased in frequency in the last decade. This change prompted us to characterize the genetic relationships of 48 recently isolated invasive H. influenzae type a (Hia), e (Hie), and f (Hif) strains by comparison of restriction digest patterns (RDPs). Recent Hia isolates exhibited moderate genetic diversity, with the majority segregating into two major clonotypes. Recent Hie and, especially, Hif strains displayed considerably restricted genetic diversity. In particular, all but one Hif strain segregated into a single clonotype, and half of these isolates had identical RDPs. These results are consistent with the hypothesis that the increased incidence of disease due to non-type b encapsulated H. influenzae reflects the emergence of hypervirulent clones, especially in the case of Hif. Alternatively, it is possible that non-type b encapsulated H. influenzae strains have limited overall genetic diversity.

Biotypes and serotypes of Haemophilus influenzae from patients with meningitis in the city of São Paulo, Brazil

A total of 1,094 Haemophilus influenzae isolates from cerebrospinal fluid were examined by biochemical and serological means. Most of them belonged to biotype I (70.9%) and to serotype b (99.4%). The relationship of biotypes I and II to the ages of the patients was shown to be significant (P < 0.001).

Evaluation of four commercial methods for identification and biotyping of genital and neonatal strains of Haemophilus species

Four commercial methods for identification of Haemophilus species were evaluated in comparison to conventional methods using 188 genital and neonatal Haemophilus strains. In the case of discrepancies between results obtained by the different methods, DNA-DNA hybridization was performed. The four commercial systems and conventional methods showed excellent correlation of results in 167 strains (88%). DNA-DNA hybridization was performed in 8 strains with discrepant identification results and 13 strains with discrepant biotyping results. In 15 cases discrepancies could be explained by the fact that the strains belonged to a newly recognised species of Haemophilus.

Evaluation of two rapid methods for identifying and biotyping Haemophilus influenzae

Several rapid method kits (one to four hours) have become available for the identification of Haemophilus and related genera. Two kits (the "Rapid NH" system and the "RIM Haemophilus" system), which include the identification and biotyping of H influenzae, were investigated for the rapid identification and biotyping of 193 isolates of H influenzae and the results compared with those obtained by more standard overnight methods. The kits were convenient to use and gave reliable and rapid speciation of all isolates. Both test systems were unreliable for biotyping: 42 isolates were wrongly biotyped by the RIM kit and 40 isolates wrongly biotyped by the rapid NH kit. It is concluded that the test kits may be useful for the rapid identification of H influenzae but that they are not reliable for the biotyping of this species.

Characterization of Haemophilus influenzae isolated from patients with otitis media

Two hundred and twenty-three Haemophilus influenzae strains isolated from patients with otitis media throughout France were characterized by biotype, serotype, antibiotic susceptibility, type of beta-lactamase production and human erythrocyte agglutination properties. All strains fell in one of two groups. One group consisted of encapsulated type b strains, 50% of which were biotype I, often resistant to ampicillin (38.5% of beta-lactamase producing strains) and seldom positive for haemagglutination (3.8%). The second group was composed of non-encapsulated strains, 42% of which were of biotype II, 10.6% beta-lactamase producers and 10.5% positive for haemagglutination.

Limited diversity of the immunoglobulin A1 protease gene (iga) among Haemophilus influenzae serotype b strains

Immunoglobulin A1 (IgA1) proteases are thought to be important virulence factors in certain bacterial infections, including meningitis, and may have potential usage in vaccines. In this study, we compared the locations of EcoRI, BamHI, and PstI restriction endonuclease sites in the IgA1 protease gene (iga) region of whole-cell DNA from 76 Haemophilus influenzae strains. The analysis was performed by using isolated fragments of the cloned iga gene, which encodes the IgA1 protease originating from a H. influenzae serotype d strain, as probes in Southern blot experiments. All strains, including three without detectable IgA1 protease activity, had DNA sequences with a high degree of homology to the iga probes. The numbers and sizes of the DNA fragments hybridizing with the probes indicated that only three strains, none of which was of serotype b, had more than one iga gene. The iga restriction fragment length patterns of 60 clinical isolates of serotype b were of only four distinct types, which correlated with previously observed clusters of multilocus genotypes (electrophoretic types). This correlation supports the concept of the clonal population structure of H. influenzae. Three of the iga gene restriction types, which appear to represent 98% of the H. influenzae serotype b population, encode IgA1 proteases that were inhibited by antisera to any one of these types and therefore could form the basis for the development of a vaccine against H. influenzae meningitis.

Types and subtypes of 73 strains of Haemophilus influenzae isolated from patients more than 6 years of age with meningitis in The Netherlands

Strains of Haemophilus influenzae isolated in The Netherlands between 1975 and 1984 from patients with meningitis were analysed in order to determine whether older patients are infected with particular types or subtypes of the organism. Of 1154 patients with H. influenzae meningitis 73 (6.3%) were more than 6 years of age. Thirty-one strains (42%) were of serotype b, one strain was of serotyped, one strain was of serotype f and 40 strains (55%) were non-typable. Twenty-eight type b strains were available for subtyping by analysis of the major outer-membrane proteins by sodium dodecylsulphate (SDS)-polyacrylamide gel electrophoresis (PAGE), by serotyping of their lipopolysaccharides and by biotyping. Twenty-one strains were outer-membrane protein subtype 1,24-lipopolysaccharide serotype 1 and 24 biotype I. Seventeen strains (61%) combined these characteristics. This percentage did not differ significantly from the percentage found for strains isolated from patients of all age groups (80%). The 32 non-typable H. influenzae strains analysed had different outer-membrane protein patterns as seen by SDS-PAGE. Five biotypes were found, among which biotype II was predominant (21/32). The results indicated that (i) patients more than 6 years of age were infected by subtypes of H. influenzae b strains which were not significantly different from the strains isolated from younger patients, (ii) non-typable strains of H. influenzae were much more common (55%) in the older age group than in the younger (1.2%) and (iii) that these non-typable strains were not of a particular subtype.

Lipopolysaccharide gel profiles of Haemophilus influenzae type b are not stable epidemiologic markers

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of lipopolysaccharide (LPS) was performed to assess the usefulness of this technique for the epidemiologic analysis of Haemophilus influenzae type b isolates. LPS samples were prepared from isolates which had been passaged either in vitro or in infant rats. Preparations from paired isolates from a number of epidemiologically related clinical situations also were examined. The gel patterns of LPS prepared on different occasions from an individual isolate were stable. However, the LPS gel patterns changed in 5 of 14 (36%) of the passaged isolates, and differences in gel patterns also were observed among epidemiologically related isolates. The variability in LPS electrophoretic patterns of individual isolates indicated that this technique is not useful for the epidemiologic analysis of H. influenzae type b disease.

Endocarditis caused by Haemophilus aegyptius

Endocarditis due to Haemophilus is uncommon. This is the first reported case caused by Haemophilus aegyptius. The course of the disease was complicated by pericarditis, congestive heart failure, and myocardial abscess formation. Surgical removal of the damaged aortic valve was not beneficial. The biologic properties of the organism included urea degradation, absence of indole metabolism, and absence of the enzyme ornithine decarboxylase.

Application of multilocus enzyme gel electrophoresis to Haemophilus influenzae

Multilocus enzyme electrophoresis was adapted to the study of Haemophilus influenzae. Protein extracts from sonicated whole bacteria were subjected to starch gel electrophoresis. After staining with substrates, the position of each isoenzyme (electromorph) was registered. Each isolate was assigned an electrophoretic type (ET) by the combination of electromorphs for the enzymes stained. Twenty-seven enzymes were tested; 12 were expressed in H. influenzae. Six enzymes were selected for subsequent study: malate dehydrogenase (MDH), phenylalanylleucine peptidase (PE2), 6-phosphogluconate dehydrogenase (6PG), adenylate kinase (AK), glucose 6-phosphate dehydrogenase (G6P), and phosphoglucose isomerase (PGI). They were polymorphic and occurred in all isolates. Six electromorphs were found for PE2, G6P, and PGI, five for MDH, four for 6PG, and three for AK. PE2, G6P, and PGI contributed most of the ET resolution (48 of 49 ETs). Multilocus enzyme electrophoresis showed several advantages over previous typing techniques. An ET could be assigned to both typable and nontypable (NT) isolates. The technique was powerful in resolving differences among isolates. The 94 isolates comprised 49 ETs, five biotypes, and six capsular types and NT isolates. Strains known to be related expressed the same ET, e.g., RAB b+ and b-, ET12; Ma a+ and a-, ET1. ET variability among type b isolates was low; 26 of 28 clinical isolates expressed ET14; 2 of 28 expressed ET13 and ET15, differing from ET14 by one electromorph each. In contrast, the 47 NT isolates comprised 38 different ETs. No ETs were shared between non-type b capsulated strains and type b or NT strains. Interestingly, five NT isolates expressed the same ET as type b strains. (iv) Strains of the same capsular type but different biotypes expressed different ETs. ET determinations will thus be useful in studying the epidemiology and evolution of H. influenzae.

Difference in structure between type b and nontypable Haemophilus influenzae populations

The extent of chromosomal genetic variability and the genetic structure of Haemophilus influenzae populations was analyzed. A total of 119 isolates from humans in Göteborg, Sweden, and Birmingham, Ala., and 16 strains from a type culture collection were characterized for capsular type, biotype, outer membrane protein profile, and enzyme electrophoretic type (ET). The results of this study indicate that the bacteria identified as H. influenzae are a genetically extremely variable array of organisms. For the six enzymes studied, the estimated mean genetic diversity was 0.57 (approximately 20% higher than the corresponding estimate for Escherichia coli). Two lines of evidence indicate that despite its ability to recombine by transformation, H. influenzae maintains a largely clonal population structure. Although there is considerable potential for generating different genotypes, there were only 88 distinct ETs among the 135 strains, and isolates of the same ET and biotype were recovered at frequencies greater than would be anticipated at random. This evidence for a clonal population structure holds for uncapsulated as well as capsulated strains. However, these data also suggest that the stability of H. influenzae clones (clone persistence time) may be less than that of the nontransforming species E. coli. The ET data indicate that there is somewhat less variability among H. influenzae strains that express the same capsular antigens, biotype, and outer membrane proteins than among randomly chosen isolates. Nevertheless, there is substantial genetic variation among isolates within each of these classes and combinations thereof. There is also variation in these typing characteristics among strains of the same ET. These observations and those on genetic variability and population structures have implications for the characterization of H. influenzae isolates in clinical and epidemiological studies.

The etiology of lobar pneumonia in the Gambia

Sixty-four patients who had been admitted to hospital in the Gambia with acute lobar pneumonia were investigated. Lung aspiration proved to be the most effective method of establishing a bacterial etiology, and Streptococcus pneumoniae was the pathogen isolated most frequently from patients irrespective of age. Among children, Haemophilus influenzae, either singly or in combination with another bacterial agent, was an important cause of pneumonia. Of 13 isolates of H. influenzae two were of serotype a, while four others were non-capsulated. All isolates of S. pneumoniae and H. influenzae were sensitive to penicillin.

A population genetic framework for the study of invasive diseases caused by serotype b strains of Haemophilus influenzae

One hundred seventy-seven isolates of serotype b Haemophilus influenzae recovered largely from children with invasive disease in the United States were characterized by the electrophoretic mobilities of 16 metabolic enzymes, the NaDodSO4/PAGE pattern of outer-membrane proteins (OMP), and biotype. Thirty-two distinctive multilocus genotypes (electrophoretic types, ETs) were distinguished on the basis of allele profiles at the enzyme loci. Twenty-eight OMP types and five biotypes were identified, but only 55 distinctive combinations of ET, OMP type, and biotype were represented. The strong nonrandom associations of characters and the recovery of isolates with identical properties in widely separated geographic regions and over a 40-year period suggest that the population structure of H. influenzae is basically clonal. Examination of nonserotype b isolates indicated that clones of serotype b are a restricted subset of the genotypes in the species as a whole. Currently, most of the invasive H. influenzae disease in the United States is caused by serotype b strains of two related ETs, and, more specifically, much of it is attributable to two subclones marked by OMP type. There is evidence that the frequency of the ET-1/OMP 1H/biotype I subclone has increased dramatically in the United States since the 1939-1954 period. The hypothesis that populations of H. influenzae are subject to marked temporal variation in clonal composition is supported by evidence of major differences in the genetic structure of populations in the United States and the Netherlands.

Distribution of biotypes of Haemophilus influenzae and H parainfluenzae in patients with cystic fibrosis

One hundred and eighty eight isolates of Haemophilus influenzae and 187 isolates of H parainfluenzae from patients with cystic fibrosis, patients with respiratory infections but without cystic fibrosis, and patients with neither cystic fibrosis nor respiratory infections were biotyped. Biotype I of H influenzae were found significantly more often in patients with cystic fibrosis compared with those with normal respiratory tracts. On the other hand, biotype II strains of H influenzae were found less often in the cystic fibrosis group. Half of the biotype V strains produced beta-lactamase.

Subtyping of Danish Haemophilus influenzae type B by their 45000 and 46000 molecular weight proteins

In order to obtain a way of subtyping Haemophilus influenzae type b strains, outer-membrane protein patterns were investigated. Outer-membrane proteins from 45 different Haemophilus influenzae type b strains were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The non-heated sarkosyl insoluble outer-membrane preparations all contained four major proteins with molecular weights (Mr) of 39,000, 33,000, 30,000, and 28,000, except for one strain which possessed a protein weighing approximately 32,000. After heating the samples a 45,000 Mr protein appeared in 43 of the strains, and a 46,000 Mr in two. The 39,000 Mr protein remained unchanged, whereas the 33,000 Mr protein disappeared. The 30,000 and the 28,000 Mr proteins became more clearly separated. A faint 16,000 Mr band was observed in both heated and non-heated samples. 42 strains with the light heat-modified protein band had identical protein patterns and could not be subdivided by the methods used and may therefore constitute a clone. The remaining strains had individual patterns.

Haemophilus influenzae biotype VIII

Six Haemophilus influenzae strains could not be classified as biotypes I through VII. The strains were indole, urease, and ornithine decarboxylase negative. We propose that they be classified as biotype VIII, a previously unreported biotype.

Laboratory identification of Haemophilus influenzae: effects of basal media on the results of the satellitism test and evaluation of the RapID NH system

The effects of four different basal media, tryptic soy agar, brain heart infusion agar, nutrient agar, and Mueller-Hinton agar, were investigated with respect to the identification of Haemophilus influenzae with a satellitism test in which X and V growth factors were supplied by factor-impregnated filter paper strips. A total of 187 recent clinical isolates of H. influenzae were examined. Of these, 179 strains (95.7%) were correctly identified with tryptic soy agar, 173 (92.5%) with brain heart infusion agar, 105 (56.1%) with nutrient agar, and 133 (71.1%) with Mueller-Hinton agar. Failure to obtain a correct identification was usually the result of satelliting growth around V factor-containing strips, possibly due to the presence of trace amounts of hemin in the basal media, or was because of an absence of growth due to nutritional deficiencies in the basal media. All 187 H. influenzae strains were also examined with a new biochemical and chromogenic substrate micromethod, the RapID NH system (Innovative Diagnostics Systems, Inc., Decatur, Ga.). A total of 168 (89.8%) strains were correctly identified with this system.

Lipopolysaccharide subtypes of Haemophilus influenzae type b from an outbreak of invasive disease

Thirty isolates of Haemophilus influenzae type b were obtained during an outbreak of invasive H. influenzae type b disease and were classified by the electrophoretic profile of their lipopolysaccharide (LPS). The LPS was extracted by a rapid micromethod and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. The isolates could be divided into 1 of 14 subtypes based on the profile of two to four bands. No subtype was predominant. However, all isolates obtained from duplicate sites of the same individual were of the same subtype. Isolates obtained from two patients (6 weeks apart) who attended the same day-care center differed in LPS subtype but were identical in their major outer membrane protein electrophoretic profile. Nasopharyngeal cultures were obtained from healthy children, their immediate families, and employees of the day-care center. Of 13 H. influenzae isolates examined from these contacts, only 1 was type b, which was obtained from a day-care worker and had the same LPS subtype and major outer membrane protein electrophoretic profile as one of the disease isolates. The remaining nasopharyngeal isolates were untypable, and most, but not all, were different in LPS pattern. Thus, LPS subtyping of H. influenzae type b may be useful in examining the predominance or transmission of a strain during an outbreak and may distinguish some strains not differentiated by outer membrane protein pattern.

Bacteremia caused by a beta-lactamase producing Haemophilus parainfluenzae strain of a new biotype. A case report

A case of Haemophilus parainfluenzae bacteremia without known infectious focus is reported. Phenotypically, the isolated strain is a typical H. parainfluenzae except for its ability to produce indole and beta-lactamase. Beta-lactamase producing H. parainfluenzae organisms are encountered occasionally, but to the best of our knowledge this is the first reported blood culture isolate with this ability. We propose a new biotype (IV) of H. parainfluenzae to accommodate strains that are indole, urease and ornithine decarboxylase positive.

The nasopharyngeal microflora of otitis-prone children, with emphasis on H. influenzae

The nasopharyngeal microflora was monitored during a prospective study of 52 otitis-prone children and 33 age-matched controls up to the age of 30 months. The relation between nasopharyngeal culture results and corresponding otoscopic findings was investigated. In contrast to pneumococci, the rate of H. influenzae isolation was correlated to the degree of otologic disease, thus it was found more often in connection with AOM than with a normal otologic status, with OME in an intermediate position. Also in contrast to pneumococci, in children with AOM, H. influenzae was commoner in the otitis-prone group than in the control group. H. influenzae biotype II was found in 77% in association with AOM in the control group. In the otitis-prone group the difference in frequency of biotypes I, II and III causing AOM were less pronounced. Turnover of H. influenzae strains as judged by change in biotype was found to occur more often in connection with treatments with penicillin-V than treatments with amoxicillin.

Antigenic heterogeneity of immunoglobulin A1 proteases from encapsulated and non-encapsulated Haemophilus influenzae

Indirect evidence suggests that immunoglobulin A1 (IgA1) proteases may be factors in the pathogenesis of certain infectious diseases, including meningitis, gonorrhoea, and destructive periodontitis. Bacterial IgA1 proteases are therefore potential candidates as vaccines. In this study, IgA1 proteases from 166 clinical isolates and reference strains of Haemophilus influenzae and Haemophilus aegyptius were compared with regard to specific activity and pattern of enzyme inhibition by antisera raised against IgA1 protease from nine selected strains of H. influenzae. A total of 93% of H. influenzae strains and all H. aegyptius strains had detectable IgA1 protease activity. The majority of strains cleaved a prolyl-seryl or a prolyl-threonyl peptide bond in the alpha 1 hinge region, whereas occasional H. influenzae strains possessed two separate IgA1 proteases with these two specific activities. Of the 155 IgA1 protease-producing strains, all except 12 could be assigned to one of 14 IgA1 protease "inhibition types," each defined by a characteristic pattern of inhibition by the nine antisera. There was no correlation between IgA1 protease type and biotype of the strains. However, among 92 encapsulated H. influenzae strains, a close correlation between capsular serotype and IgA1 protease type was observed. With the exception of serotype f, strains of all capsular serotypes produced an exclusive antigenic type of IgA1 protease. All 38 strains of serotype b produced IgA1 protease of inhibition type 1, which was never demonstrated in non-encapsulated H. influenzae strains. These results facilitate the detection of an antibody response against specific IgA1 proteases and are of practical value for a possible future vaccine against H. influenzae serotype b infections.

Novel method of biotyping Haemophilus influenzae that uses API 20e

One hundred Haemophilus influenzae isolates from various body sites were biotyped by conventional methods and by the API 20E system (Analytab Products, Plainview, N.Y.). By using a hemin- and a nicotinamide adenine dinucleotide-enriched saline solution as the inoculating fluid for the API 20E, a 100% correlation of results was obtained between the two methods. Ninety percent of the blood and cerebrospinal fluid isolates were biotype I. Biotype II was the predominant biotype encountered overall. No correlation was observed between beta-lactamase production and biotype. The API 20E is a reliable method and should prove useful for routine biotyping of H. influenzae in the clinical laboratory.

Differentiation of Haemophilus spp. in Respiratory isolate cultures by an indole spot test

Indole spot tests using isolated, nonhemolytic colonies of Haemophilus species were positive for 90 of 151 (60%) respiratory isolates of Haemophilus influenzae, whereas 67 to 72 (93%) isolates of H. influenzae from cerebrospinal fluid and blood specimens were indole positive. Only 4 of 117 (3%) Haemophilus parainfluenzae isolates were positive for indole spot tests. Thus, indole-positive, nonhemolytic Haemophilus isolates in respiratory cultures can be presumptively identified as H. influenzae.

Outer membrane protein subtypes and investigation of recurrent Haemophilus influenzae type b disease

Ten previously healthy patients, ages 3 to 26 months, developed recurrent episodes of deep-tissue Haemophilus influenzae type b infections from 4 to 191 days (median = 28 days) after the last day of antibiotic therapy given for the first episode. None of the patients had a persistent focus of infection and eight were considered to have had adequate therapy for the initial episode. Bacteremia, without evidence of relapse at the site of the original infection, was documented in eight of the ten recurrent episodes. The ampicillin susceptibilities of the HITB isolates changed between episodes in two of the patients. Blood or CSF isolates from both episodes in seven patients were examined for biotypes and outer membrane protein subtypes. Concordance of both biotype and OMP subtype was present for all seven paired isolates, including the two pairs in which the HITB ampicillin sensitivities had changed. These data imply that some patients become reinfected with their original HITB isolates and that OMP and capsular antigens do not always elicit protective immunity, even after natural infection.

Differential complement resistance mediates virulence of Haemophilus influenzae type b

Studies were undertaken to gain insight into the virulence of type b in contrast to the other Haemophilus influenzae capsular types. A relationship was found between the comparative virulence of H. influenzae types in humans and their resistance to the bactericidal effect of antibody-free complement. Type b was most resistant to the bactericidal effect of complement. The other types could be divided into three groups based upon their susceptibility to complement; this grouping was also related to their structural similarities. No association between virulence and either the biotype, source of isolate, in vitro association with peripheral polymorphonuclear leukocytes, or the total amount of capsular polysaccharide was found. However, among the type b strains, higher levels of cell-associated polysaccharide were associated with increased resistance to complement. The relative virulence of the six H. influenzae types in the infant rat model was generally similar to that in humans. After intraperitoneal challenge, type b and type a strains had the lowest 50% effective doses for bacteremia, removed by several logs from the values of the other types. By intranasal challenge, type b strains produced higher rates and levels of bacteremia than did type a strains. High levels of natural bactericidal antibodies to types c and e were found in adult female rats; this finding alone could not account for the differences in virulence among the H. influenzae types in the infant rat model. We propose that the virulence of type b strains is due to their greater resistance to the bactericidal activity of serum complement alone. Resistance to type b disease requires serum antibody to induce the complement-mediated reaction.

Biochemical characterization of Haemophilus species with the minitek differentiation system

Characterization of 102 Haemophilus strains by the Minitek differentiation system (BBL Microbiology Systems, Cockeysville, Md.) was compared with that by the conventional method. The results obtained by the two methods were in good agreement (P less than 0.001; test of independence). Therefore, this system was found to be applicable for the identification of Haemophilus species in routine clinical bacteriology.

Limited in vitro activity of cefamandole against 100 beta-lactamase- and non-beta-lactamase-producing Haemophilus influenzae strains: comparison of moxalactam, chloramphenicol, and ampicillin

In the present study, the minimal inhibitory concentrations and minimal bactericidal concentrations of moxalactam, cefamandole lithium, ampicillin, and chloramphenicol were determined, both in broth and on solid medium, against 75 non-beta-lactamase-producing and 25 beta-lactamase-producing strains of Haemophilus influenzae. Most of the 75 strains were inhibited or killed by 2 microgram or less of ampicillin, chloramphenicol, or moxalactam per ml, but cefamandole exhibited poor bactericidal activity against 11 non-beta-lactamase-producing strains, of which 9 were non-type B H. influenzae. Most of the 25 beta-lactamase-producing H. influenzae were resistant to 128 microgram of ampicillin per ml. Both moxalactam and chloramphenicol, which had minimal inhibitory concentrations of less than 0.25 and 2 microgram/ml, respectively, were more active than cefamandole, which had a minimal inhibitory concentration ranging from 2 to greater than or equal to 128 microgram/ml.

Biotypes of capsulated and non-capsulated Haemophilus influenzae. Correlation between biotypes and beta-lactamase production

396 Haemophilus influenzae strains were biotyped according to Kilian. 393 of the strains were assigned to biotypes I to V, while 3 strains remained unclassified. Eighty-nine per cent of the capsulated strains produced both urease and ornithine decarboxylase, biotypes I or IV, while 95 per cent of the non-capsulated strains produced only one of the enzymes, biotypes II, III, or V. Of consecutive strains from the upper respiratory tract, the incidence of beta-lactamase-positive strains was higher among capsulated than among non-capsulated strains (p less than 0.025). None of 133 non-capsulated beta-lactamase-positive strains produced both urease and ornithine decarboxylase, in contrast to 15 out of 147 non-capsulated beta-lactamase-negative strains (p less than 0.001). The type e strains were all of biotype IV and 3 of 7 consecutive strains were beta-lactamase-positive.

Rapid biochemical characterization of Haemophilus species by using the micro-ID

Biotyping of Haemophilus influenzae into five type and H. parainfluenzae into three types based on indole production, ornithine decarboxylase, and urease has been reported (M. Kilian, Acta Pathol. Microbiol. Scand. Sect. B 82:835--842, 1976). A commercially available test system designed for the 4-h identification of Enterobacteriaceae. Micro-ID, proved efficacious for the rapid biotyping of these two Haemophilus species. The nitrate reductase, indole production, ornithine decarboxylase, urease, and o-nitrophenyl-beta-D-galactopyranoside hydrolysis tests in Micro-ID correlated over 99% with conventional methodology. By utilizing the indole and o-nitrophenyl-beta-D-galactopyranoside tests it was possible, with 261 of 272 (96.1%) isolates, to distinguish H. influenzae from H. parainfluenzae. Cerebrospinal fluid isolates were over 90% H. influenzae biotype I, and conjunctival isolates were approximately 70% biotype II. Type b H. influenzae were predominantly biotypes I and II; these type b isolates were also overwhelmingly indole producers. Although over 90% of biotypes I and II have been reported to produce beta-lactamase, this was not confirmed by the small number of beta-lactamase producers encountered here. The 4-h Micro-ID should prove a useful mechanism, amenable to the routine clinical laboratory, for the further exploration of the association of Haemophilus with the site of isolation, antigenicity, and antibiotic resistance.