Haemophilus Parahaemolyticus Research Articles

Comparison of the sputum microbiome between patients with stable nontuberculous mycobacterial pulmonary disease and patients requiring treatment.

We evaluated whether the sputum bacterial microbiome differs between nontuberculous mycobacteria pulmonary disease (NTM-PD) patients with stable disease not requiring antibiotic treatment and those requiring antibiotics. We collected sputum samples from 21 clinically stable NTM-PD patients (stable group) and 14 NTM-PD patients needing antibiotic treatment (treatment group). We also obtained 13 follow-up samples from the stable group. We analyzed the 48 samples using 16S rRNA gene sequencing (V3-V4 region) and compared the groups. In the linear discriminant analysis effect size (LEfSe) analysis, the species Porphyromonas pasteri, Haemophilus parahaemolyticus, Prevotella nanceiensis, and Gemella haemolysans were significantly more prevalent in the sputum of the stable group compared to the treatment group. No taxa showed significant differences in alpha-/beta-diversity or LEfSe between the 21 baseline and 13 follow-up sputum samples in the stable group. In the stable group, the genus Bergeyella and species Prevotella oris were less common in patients who achieved spontaneous culture conversion (n = 9) compared to those with persistent NTM positivity (n = 12) (effect size 3.04, p = 0.039 for Bergeyella; effect size 3.64, p = 0.033 for P. oris). In the treatment group, H. parainfluenzae was more common in patients with treatment success (n = 7) than in treatment-refractory patients (n = 7) (effect size 4.74, p = 0.013). Our study identified distinct bacterial taxa in the sputum of NTM-PD patients based on disease status. These results suggest the presence of a microbial environment that helps maintain disease stability.

Comparative analysis of microbial composition and functional characteristics in dental plaque and saliva of oral cancer patients

BackgroundThe oral cavity is home to various ecological niches, each with its own unique microbial composition. Understanding the microbial communities and gene composition in different ecological niches within the oral cavity of oral cancer (OC) patients is crucial for determining how these microbial populations contribute to disease progression.MethodsIn this study, saliva and dental plaque samples were collected from patients with OC. Metagenomic sequencing was employed to analyze the microbial community classification and functional composition of the different sample groups.ResultsThe results of the study revealed significant differences in both the function and classification of microbial communities between saliva and dental plaque samples. The diversity of microbial species in saliva was found to be higher compared to that in plaque samples. Notably, Actinobacteria were enriched in the dental plaque of OC patients. Furthermore, the study identified several inter-group differential marker species, including Prevotella intermedia, Haemophilus parahaemolyticus, Actinomyces radius, Corynebacterium matruchitii, and Veillonella atypica. Additionally, 1,353 differential genes were annotated into 23 functional pathways. Interestingly, a significant correlation was observed between differentially labeled species and Herpes simplex virus 1 (HSV-1) infection, which may be related to the occurrence and development of cancer.ConclusionsSignificant differences in the microbial and genetic composition of saliva and dental plaque samples were observed in OC patients. Furthermore, pathogenic bacteria associated with oral diseases were predominantly enriched in saliva. The identification of inter-group differential biomarkers and pathways provide insights into the relationship between oral microbiota and the occurrence and development of OC.

Diagnostic strategy of metagenomic next-generation sequencing for gram negative bacteria in respiratory infections

ObjectiveThis study aims to identify the most effective diagnostic method for distinguishing pathogenic and non-pathogenic Gram-negative bacteria (GNB) in suspected pneumonia cases using metagenomic next-generation sequencing (mNGS) on bronchoalveolar lavage fluid (BALF) samples.MethodsThe effectiveness of mNGS was assessed on BALF samples collected from 583 patients, and the results were compared with those from microbiological culture and final clinical diagnosis. Three interpretational approaches were evaluated for diagnostic accuracy.ResultsmNGS outperformed culture significantly. Among the interpretational approaches, Clinical Interpretation (CI) demonstrated the best diagnostic performance with a sensitivity of 87.3%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 98.3%. CI’s specificity was significantly higher than Simple Interpretation (SI) at 37.9%. Additionally, CI excluded some microorganisms identified as putative pathogens by SI, including Haemophilus parainfluenzae, Haemophilus parahaemolyticus, and Klebsiella aerogenes.ConclusionProper interpretation of mNGS data is crucial for accurately diagnosing respiratory infections caused by GNB. CI is recommended for this purpose.

Changes in the airway microbiome in patients with bronchiectasis.

This study used metagenomic next-generation sequencing (mNGS) technology to explore the changes of the microbial characteristics in the lower respiratory tract in patients with acute exacerbations of bronchiectasis (noncystic fibrosis) to guide clinical treatment and improve patients' quality of life and prognosis. This prospective study included 54 patients with acute exacerbation and 46 clinically stable patients admitted to the Respiratory and Critical Care Medicine Center of the People's Hospital of Xinjiang Uygur Autonomous Region from January 2020 to July 2022. Sputum was subjected to routine microbiological tests, and bronchoalveolar lavage fluid (BALF) samples were subjected to microbiological tests and mNGS of BALF before empirical antibiotic therapy. Serum inflammatory markers (white blood cell count, interleukin-6, procalcitonin, and C-reactive protein) were measured. In addition, we evaluated the pathogen of mNGS and compared the airway microbiome composition of patients with acute exacerbation and control patients. The mean age of our cohort was 56 ± 15.2 years. Eighty-nine patients had positive results by mNGS. There was a significant difference in the detection of viruses between the groups (χ2 = 6.954, P < .01). The fungal species Candida albicans, Pneumocystis jirovecii, and Aspergillus fumigatus were significantly more common in patients with acute exacerbations (χ2 = 5.98, P = .014). The bacterial species Acinetobacter baumannii, Mycobacterium tuberculosis, Haemophilus influenzae, Haemophilus parahaemolyticus, Abiotrophia defectiva, and Micromonas micros were significantly more prevalent in patients with acute exacerbations (χ2 = 4.065, P = .044). The most common bacterial species isolated from the sputum and BALF samples of patients with acute exacerbation was A. baumannii. Chlamydia psittaci was found in 4 patients. In addition, of 77 patients with negative sputum culture, 66 had positive results by mNGS, demonstrating the increased sensitivity and accuracy of mNGS. Patients with acute exacerbation of bronchiectasis tend to have mixed infections in the lower respiratory tract. The frequency of viruses, fungi, and Mycoplasma was higher in these patients. Our findings suggest that mNGS could be used to identify pathogenic microorganisms in these patients, increasing the effectiveness of antibiotic therapy.

Microbial communities of the upper respiratory tract in mild and severe COVID-19 patients: a possible link with the disease course

The microbiota of the respiratory tract remains a relatively poorly studied subject. At the same time, it is involved in modulating the immune response to infectious agents in the host organism, just like the intestinal microbiota. A relationship between the composition of the respiratory microbiota and the likelihood of development and the severity of COVID-19 may be assumed. In this study, we applied the 16S rRNA metagenomic sequencing to analyze the oropharyngeal swabs from 120 COVID-19 patients collected during the first and the second waves of the COVID-19 epidemic in Russia. Differential abundance analysis with respect to comorbidities suggested association of Neisseria oralis, Neisseria mucosa, unidentified Veillonella spp., Lautropia mirabilis species with more severe lung damage, and Streptococcus salivarius, Capnocytophaga sputigena and Haemophilus parahaemolyticus with a milder course of the disease. We hypothesize that the latter bacteria (or some of them) might be beneficial for the respiratory tract and might be able to alleviate the course of the COVID-19 disease.

PathogenTrack and Yeskit: tools for identifying intracellular pathogens from single-cell RNA-sequencing datasets as illustrated by application to COVID-19.

Pathogenic microbes can induce cellular dysfunction, immune response, and cause infectious disease and other diseases including cancers. However, the cellular distributions of pathogens and their impact on host cells remain rarely explored due to the limited methods. Taking advantage of single-cell RNA-sequencing (scRNA-seq) analysis, we can assess the transcriptomic features at the single-cell level. Still, the tools used to interpret pathogens (such as viruses, bacteria, and fungi) at the single-cell level remain to be explored. Here, we introduced PathogenTrack, a python-based computational pipeline that uses unmapped scRNA-seq data to identify intracellular pathogens at the single-cell level. In addition, we established an R package named Yeskit to import, integrate, analyze, and interpret pathogen abundance and transcriptomic features in host cells. Robustness of these tools has been tested on various real and simulated scRNA-seq datasets. PathogenTrack is competitive to the state-of-the-art tools such as Viral-Track, and the first tools for identifying bacteria at the single-cell level. Using the raw data of bronchoalveolar lavage fluid samples (BALF) from COVID-19 patients in the SRA database, we found the SARS-CoV-2 virus exists in multiple cell types including epithelial cells and macrophages. SARS-CoV-2-positive neutrophils showed increased expression of genes related to type I interferon pathway and antigen presenting module. Additionally, we observed the Haemophilus parahaemolyticus in some macrophage and epithelial cells, indicating a co-infection of the bacterium in some severe cases of COVID-19. The PathogenTrack pipeline and the Yeskit package are publicly available at GitHub.Electronic Supplementary MaterialSupplementary material is available in the online version of this article at 10.1007/s11684-021-0915-9 and is accessible for authorized users.

Meta-analysis of the lung microbiota in pulmonary tuberculosis

The lung microbiota has received less attention compared to other body sites, in part because its study carries special technological difficulties related to obtaining reliable samples as compared to other body niches. The limited number of studies on the sputum microbiota on TB patients and controls available so far have reported inconsistent, and sometimes, contradictory results. Aiming to clarify if changes in the lung microbiota composition are associated with pulmonary TB, we performed a meta-analysis of available data on microbiota of the lower respiratory tract in TB patients and healthy controls. Re-processing next generation sequencing data under uniform parameters and utilizing state-of-the-art bioinformatics analysis, we obtained distinct clusterings of microbiota between TB cases vs. controls across multiple studies. We identified Tumebacillus ginsengisoli, Propionibacterium acnes, Haemophilus parahaemolyticus as differentially abundant species signature in healthy controls while Caulobacter henricii, Actinomyces graevenitzii, Rothia mucilaginosa, in addition to Mycobacterium tuberculosis as differentially abundant species signature in TB cases, and described R. mucilaginosa as the anchoring species in a network of bacteria co-occurring with Mycobacterium tuberculosis (Mtb) infection.

Difficulties in species identification within the genus Haemophilus - A pilot study addressing a significant problem for routine diagnostics.

Diagnostic misidentifications of commensalic Haemophilus haemolyticus as pathogenic Haemophilus influenzae are frequent. This pilot study evaluates whether isolations of H. haemolyticus are frequent enough in Germany to cause a relevant diagnostic problem, considering the fact that even H. influenzae is a mere colonizer in about 30% of isolations. In microbiological laboratories of two hospitals located in Northern and Southern Germany, the distribution of Haemophilus spp. was analyzed during a six-month-period. Site of infection, sex, and age of the patients was taken into consideration. A total of 77 Haemophilus spp. isolates was acquired and discriminated on species level, comprising: 48 H. influenzae, 25 Haemophilus parainfluenzae, 3 H. haemolyticus, and 1 Haemophilus parahaemolyticus. The proportion of H. haemolyticus was calculated to range between 1.2% and 16.2 % within the 95% confidence limits. Commensalic Haemophilus spp. were isolated from oropharynx-associated sites only. H. influenzae, in contrast, was detected in clinically relevant materials like lower respiratory materials and conjunctiva swabs. Altogether, there was a low proportion of clinical H. haemolyticus isolates. Accordingly, the problem of unnecessary antibiotic therapies due to misidentifications of H. haemolyticus as H. influenzae is quantitatively negligible compared with the risk of confusing H. influenzae colonizations with infections.

Antimicrobial efficacy and phytochemical analysis of &lt;i&gt;Indigofera trita&lt;/i&gt; Linn

An in vitro antimicrobial activity and phytochemical analysis of various extracts of Indigofera trita L. viz. petroleum ether, chloroform, acetone, ethanol and aqueous extracts were carried out. A total of 21 microorganisms (19 bacteria and 2 fungal strains) were used for antimicrobial activity by disc diffusion method and a standard procedure was used to identify the phytochemical constituents. Petroleum ether extract showed moderate inhibitory activity against Staphylococcus aureus (14.40 mm), S. epidermidis (14.20 mm), Salmonella paratyphi A (12.80 mm), Streptococcus mutans (12.20 mm), Escherichia coli, Proteus vulgaris, S. typhi and Burkholderia cepacia (12.00 mm). The chloroform extract also showed antimicrobial activity against S. epidermidis (14.20 mm), S. typhimurium (12.60 mm), S. paratyphi A, S. brunei and Yersinia enterocolitica (12.00 mm). The acetone extract of I. trita showed considerable inhibitory activity against S. epidermidis (18.20 mm), S. typhimurium (14.60 mm), S. infantis (13.80 mm), S. aureus (13.40 mm), Y. enterocolitica (13.00 mm) and Enterobacter aerogenes (12.00 mm) were documented. Ethanol extract showed significant antimicrobial activity against S. epidermidis (18.60 mm), S. paratyphi A (14.60 mm), Y. enterocolitica (13.40 mm), S. typhi (12.40 mm), S. aureus, E. aerogenes, S. typhimurium and S. infantis (12.00 mm). Aqueous extract of I. trita considerably inhibited S. epidermidis (13.80 mm), S. paratyphi A and Y. enterocolitica (12.20 mm), E. aerogenes and Haemophilus parahaemolyticus (12.00 mm). All the five extracts showed a minimal antifungal activity when compared to antibacterial activity. The result revealed that the antimicrobial properties of I. trita might be associated with the presence of phenolic compounds, flavonoids, tannins, glycosides, saponins, phytosterols and alkaloids.

Identification of haemolytic Haemophilus species isolated from human clinical specimens and description of Haemophilus sputorum sp. nov

Haemolytic Haemophilus strains with no requirement for X factor are regularly isolated from sputum and throat swabs and occasionally from invasive infections, but the classification of such strains is not clear. We characterized 56 strains with a phenotype concordant with Haemophilus parahaemolyticus (V, but not X factor-dependent; urease-positive; tryptophanase-negative; ornithine decarboxylase-negative) by extended phenotypic testing and 16S rRNA gene sequencing. In addition, 31 of the strains and representative type strains were investigated by multilocus sequence analysis based on 3 housekeeping gene fragments. Most strains could be assigned to H. parahaemolyticus and were characterized by expression of IgA1 protease and a negative test for β-galactosidase. Isolation of H. parahaemolyticus from various infections and its absence among more than 300 commensal Haemophilus isolates suggests a pathogenic potential of this organism. The majority of haemolytic strains with β-galactosidase activity did not cluster with the type strain of H. paraphrohaemolyticus, but constituted a distinct and coherent novel taxon. Ten strains of this new taxon proved to be genetically and phenotypically homogeneous. Few biochemical characters discriminate the new taxon from related Haemophilus species, but identification is easily accomplished by routine matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Genetic, biochemical, and spectrometry data show that the taxon merits recognition as a novel species of Haemophilus. The name Haemophilus sputorum is proposed, with CCUG 13788T (=DSM 24472T=NCTC 13537T) as the type strain.

The micro-flora of the small bowel in health and disease

The micro-flora of the proximal jejunum in healthy volunteers was compared with the micro-flora in patients with gastrointestinal symptoms suggestive of spontaneous bacterial overgrowth in the small intestine. Biopsies were taken distally to the ligament of Treitz with a Watson capsule. The samples were diluted and inoculated on selective and non-selective agar plates that were incubated aerobically and anaerobically. No major differences were found in the small jejunum micro-flora in healthy persons or in a heterogenous group of patients with gastrointestinal disorders. Oropharyngeal micro-organisms dominated the micro-flora in all subjects and colonic micro-organisms were found in low numbers in a few subjects from both groups. Streptococcus intermedius and Haemophilus parahaemolyticus were only found in the micro-flora of healthy subjects while Lactobacillus spp. was more frequently found in the samples from patients. Eight of 20 healthy subjects and five of 18 patients met the criterion of small intestinal overgrowth. Emerging evidence suggests that other factors are involved in the pathogenesis of the irritable bowel syndrome complex. There is a need for better understanding of the complicated interactions between the host and the endogenous micro-flora.

Cloning and Analysis of the Genes Encoding the Type IIS Restriction-Modification System HphI from Haemophilus Parahaemolyticus

The genomic region encoding the type IIS restriction-modification (R-M) system HphI (enzymes recognizing the asymmetric sequence 5'-GGTGA-3'/5'-TCACC-3') from Haemophilus parahaemolyticus were cloned into Escherichia coli and sequenced. Sequence analysis of the R-M HphI system revealed three adjacent genes aligned in the same orientation: a cytosine 5 methyltransferase (gene hphIMC), an adenine N6 methyltransferase (hphIMA) and the HphI restriction endonuclease (gene hphIR). Either methyltransferase is capable of protecting plasmid DNA in vivo against the action of the cognate restriction endonuclease. hphIMA methylation renders plasmid DNA resistant to R.Hindill at overlapping sites, suggesting that the adenine methyltransferase modifies the 3'-terminal A residue on the GGTGA strand. Strong homology was found between the N-terminal part of the m6A methyltransferasease and an unidentified reading frame interrupted by an incomplete gaIE gene of Neisseria meningitidis. The HphI R-M genes are flanked by a copy of a 56 bp direct nucleotide repeat on each side. Similar sequences have also been identified in the non-coding regions of H.influenzae Rd DNA. Possible involvement of the repeat sequences in the mobility of the HphI R-M system is discussed.

Binding of human hemoglobin by Haemophilus influenzae

Binding of biotinylated human hemoglobin to Haemophilus influenzae was detected when organisms were grown in heme-deplete, but not heme-replete, conditions. Hemoglobin binding was completely inhibited by a 100-fold excess of unlabelled human hemoglobin or human hemoglobin complexed with human haptoglobin. Binding was only partially inhibited by rat hemoglobin, bovine hemoglobin, human globin, and bovine globin, and not at all by heme, human serum albumin, bovine serum albumin, human transferrin, or myoglobin. Hemoglobin binding was saturable at 16–20 ng of hemoglobin per 109 cfu. Binding of human hemoglobin was detected in serotypes a-f and serologically non-typable strains of H. influenzae, as well as Haemophilus haemolyticus but not Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus parahaemolyticus, or Escherichia coli.

Binding of human hemoglobin by Haemophilus influenzae.

Binding of biotinylated human hemoglobin to Haemophilus influenzae was detected when organisms were grown in heme-deplete, but not heme-replete, conditions. Hemoglobin binding was completely inhibited by a 100-fold excess of unlabelled human hemoglobin or human hemoglobin complexed with human haptoglobin. Binding was only partially inhibited by rat hemoglobin, bovine hemoglobin, human globin, and bovine globin, and not at all by heme, human serum albumin, bovine serum albumin, human transferrin, or myoglobin. Hemoglobin binding was saturable at 16-20 ng of hemoglobin per 10(9) cfu. Binding of human hemoglobin was detected in serotypes a-f and serologically non-typable strains of H. influenzae, as well as Haemophilus haemolyticus but not Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus parahaemolyticus, or Escherichia coli.

Comparison of the RIM-H rapid identification kit with conventional tests for the identification of Haemophilus spp

A commercially available system, the RIM-H system (Austin Biological Laboratories, Austin, Tex.), was evaluated for its ability to rapidly and accurately identify various Haemophilus spp. A total of 110 clinical isolates were tested by both the RIM and conventional identification procedures. The RIM agreed with the standard identification for 100% of the Haemophilus influenzae (76 of 76) and 92.0% of the Haemophilus parainfluenzae (23 of 25) isolates tested. The identifications of Haemophilus parahaemolyticus, Haemophilus aphrophilus, and Haemophilus haemolyticus also correlated with those obtained by conventional methods. The RIM was found to be rapid and easy to use and was considered a suitable alternative to conventional identification procedures.

Characterisation of Histophilus ovis and related organisms by restriction endonuclease analysis

The banding profiles generated by Bam H1 restriction endonuclease cleavage of bacterial DNA from clinical and reference isolates of Histophilus ovis, Haemophilus somnus and related bacteria were compared. H. ovis, H. somnus and Haemophilus agni isolates were found to have distinct similarities in banding profiles characterised by 10 common bands between 2.0 and 9.6 kilobases (kb). The close taxonomic relationship of these isolates was reinforced by these findings. The reference isolates examined in this study--Actinobacillus lignieresii, Actinobacillus seminis, H. agni, H. somnus, H. ovis, Haemophilus influenzae, Haemophilus parainfluenzae, Haemophilus parahaemolyticus--could be distinguished from each other on the basis of their characteristic banding profiles. Actinobacillus sp were observed to have more bands between 2 and 23 kb compared with the H. ovis and Haemophilus sp isolates studied. Analysis of isolates from an experimental infection trial illustrated the potential of restriction endonuclease analysis in molecular epidemiological applications. It was possible to demonstrate by this means that the post-challenge isolates had identical banding profiles to the challenge (or infecting) isolate which had a distinctly different banding profile from that of pre-challenge H. ovis isolates. Furthermore, restriction endonuclease analysis of H. ovis isolates obtained from follow-up investigations of a recurrent problem of epididymitis in unmated rams, indicated that the H. ovis isolates implicated in epididymitis, were present as a single strain in a number of sheep over a period of time. This suggested that the mechanism of transmission was by perinatal perputial contamination.

Relatedness within the Family Pasteurellaceae as Determined by Genetic Transformation

Genetic transformation studies were used to determine relatedness within the family Pasteurellaceae. Among strains with &lt; 60% relatedness to Haemophilus influenzae based on deoxyribonucleic acid hybridization, two groups were identified; one, showing competition for homospecific transformation with H. influenzae, contained Haemophilus parainfluenzae, Haemophilus parasuis, Haemophilus aphrophilus, Haemophilus paraphrophilus, Pasteurella pneumotropica, Pasteurella multocida, and Actinobacillus actinomycetemcomitans, and the other, showing little or no competition for homospecific transformation with H. influenzae, contained Haemophilus ducreyi, Haemophilus parahaemolyticus, Actinobacillus lignieresii, Actinobacillus equuli, Actinobacillus pleuropneumoniae, and Pasteurella ureae. Such groupings support existing studies which have used only deoxyribonucleic acid hybridization or numerical analysis.

Reassignment of Actinobacillus actinomycetemcomitans to the Genus Haemophilus as Haemophilus actinomycetemcomitans comb. nov.

Serological techniques were used to assess the relationships among the following species: Actinobacillus equuli, Actinobacillus lignieresii, Actinobacillus pleuropneumoniae, “Actinobacillus seminis”, Actinobacillus suis, Actinobacillus actinomycetemcomitans Haemophilus aphrophilus, Haemophilus paraphrophilus, Haemophilus segnis, Haemophilus parainfluenzae, Haemophilus influenzae, Haemophilus parahaemolyticus, Haemophilus aegyptius, and Gardnerella vaginalis. Deoxyribonucleic acid-deoxyribonucleic acid hybridization analyses of A. actinomycetemcomitans, H. segnis, H. aphrophilus, and H. paraphrophilus showed that these four species have measurable deoxyribonucleic acid relatedness of 28% or greater, consistent with their placement in a single genus. These bacterial species also demonstrated common antigens by immunodiffusion. In view of these genetic and serological relationships and previous inclusion of X- and V-factor-independent bacterial species in the genus Haemophilus, reassignment of A. actinomycetemcomitans to the genus as Haemophilus actinomycetemcomitans comb. nov. is proposed.

Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization Analysis of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

Deoxyribonucleic acids (DNAs) were isolated and purified from 20 strains of Actinobacillus actinomycetemcomitans, 6 strains of Haemophilus aphrophilus, 2 strains of Haemophilus paraphrophilus, 2 strains of Haemophilus pleuropneumoniae, 2 strains of Haemophilus paraphrohaemolyticus, 2 strains of Haemophilus influenzae, and 1 strain each of Actinobacillus lignieresii, Actinobacillus suis, Haemophilus aegyptius, Haemophilus parainfluenzae, and Haemophilus parahaemolyticus. The guanine-plus-cytosine contents of the DNAs were determined, and they agreed closely with previous estimates. DNA-DNA hybridization analyses revealed that all of the strains identified as A. actinomycetemcomitans were at least 69% homologous to DNA probes from two A. actinomycetemcomitans strains (strains NCTC 9710T [T = type strain] and Y4). The H. aphrophilus and H. paraphrophilus strains were homologous to the two A. actinomycetemcomitans probes at levels of 25 to 37%. The DNAs of all A. actinomycetemcomitans strains were homologous to a DNA probe from H. aphrophilus strain NCTC 5906 at levels of 30 to 39%. The two strains of H. paraphrophilus tested were homologous to the H. aphrophilus probe at levels of 73 and 77%, indicating a very close relationship between these groups of organisms. H. parainfluenzae strain ATCC 9796 DNA seemed to be homologous to the H. aphrophilus and A. actinomycetemcomitans probes at low but significant levels (12 to 16%). All of the other strains of haemophili and actinobacilli tested gave 10% or less homology with the three test probes.

Field testing of a killed Haemophilus parahaemolyticus vaccine in pigs.

SUMMARY Piglets immunised with a formalin inactivated alum precipitated vaccine prepared from Haemophilus parahaemolyticus serotype 1 and born to sows treated before farrowing with an alum hydroxide adjuvant vaccine had a lower mortality rate and death rate from pleuropneumonia than control piglets.