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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The tonsils of 97 children undergoing tonsillectomy were studied to determine the correlation between surface culture swab and culture of tonsillar core. In many cases, pathogenic organisms were found in the tonsil core, despite the fact that surface cultures revealed only normal respiratory flora. The tonsil core cultures showed a high incidence of Hemophilus influenzae and Staphylococcus aureus, which was rarely reflected on surface culture. The study indicates that pharyngeal swab cultures do not reliably reflect the presence of pathogens in the tonsil core. The value of parameters such as history of recurrent bouts of tonsillitis and presence of erythema or cryptic debris on physical examination for predicting the differential bacteriology of the tonsil is studied. The implications for treatment of children with adenotonsillar hypertrophy are discussed.
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PMID:Bacteriology of tonsil surface and core in children. 264 91

Fifty-nine percent of unselected strains of Haemophilus parainfluenzae were found to carry small, phenotypically cryptic plasmid DNA species. Using filter blot hybridization, we found several plasmids which were homologous to the small beta-lactamase-specifying plasmids pJB1 and pFA7, which were originally isolated from Haemophilus ducreyi and Neisseria gonorrhoeae, respectively. Detailed filter hybridization studies combined with electron microscope heteroduplex analysis suggested that three cryptic plasmids are completely homologous to the non-TnA sequences of pJB1. One cryptic plasmid was found to be highly homologous to pJB603, a small beta-lactamase plasmid previously found in two isolates of H. influenzae. A second group of plasmids were found to carry sequences homologous to pJB1 and other sequences homologous to pJB603. These results strongly suggest that small beta-lactamase plasmids found in Haemophilus species and N. gonorrhoeae may have arisen by insertion of the transposable beta-lactamase-specifying element TnA into small, phenotypically cryptic replicons resident in H. parainfluenzae. Attempts to reproduce such a recombination event in the laboratory were not successful.
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PMID:Origin of small beta-lactamase-specifying plasmids in Haemophilus species and Neisseria gonorrhoeae. 302 2

Ampicillin resistance in Haemophilus influenzae and Neisseria gonorrhoeae is most commonly due to plasmid-mediated production of the TEM beta-lactamase. The H. influenzae plasmids may have evolved by insertion of various antibiotic resistance transposons into a phenotypically cryptic plasmid found in one of 699 isolates of H. influenzae examined. The small, nonconjugative, beta-lactamase-specifying plasmids of N. gonorrhoeae and Haemophilus species are highly related. Phenotypically cryptic plasmids found in several epidemiologically distinct isolates of Haemophilus parainfluenzae are highly related to the beta-lactamase plasmids but carry no transposon A (TnA) sequences. This evidence strongly favors the hypothesis that the beta-lactamase plasmids evolved by the insertion of TnA (possibly introduced from enteric bacteria) into cryptic plasmids resident in H. parainfluenzae.
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PMID:Molecular epidemiology of antibiotic resistance plasmids of Haemophilus species and Neisseria gonorrhoeae. 302 90

A clinical isolate of Haemophilus ducreyi was found to harbor three plasmids: a 23.5-megadalton (Mdal) phenotypically cryptic plasmid, a 7.0-Mdal ampicillin resistance plasmid, and a 4.0-Mdal sulfonamide resistance plasmid. The two smaller plasmids were transferable by conjugation to Haemophilus recipients, but only if the donor cell harbored the 23.5-Mdal plasmid as well, indicating that this large plasmid had mobilizing capabilities. Transfer was also possible to Escherichia coli recipients. Haemophilus influenzae transconjugants which had acquired both the 23.5-Mdal plasmid and one of the R-plasmids could subsequently retransfer the R-plasmid to other Haemophilus recipients at higher frequencies. A derivative of the 23.5 Mdal plasmid was isolated which was shown by restriction endonuclease analysis to contain an ampicillin resistance transposon and to have retained its conjugative ability.
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PMID:Mobilization of nonconjugative antibiotic resistance plasmids in Haemophilus ducreyi. 627 68

Piliated, competent gonococci are known to preferentially take up homologous transforming DNA into the cell. We examined the mechanism for DNA uptake with pFA10, a hybrid 11.5-kilobase (kb) penicillin-resistant (Pcr) plasmid composed of heterologous DNA from a 7.2-kb Pcr plasmid and homologous DNA from a 4.2-kb gonococcal cryptic plasmid. The presence of the gonococcal cryptic plasmid DNA in the hybrid resulted in markedly increased transformation efficiencies in isogenic crosses as compared with the parent 7.2-kb Pcr plasmid. Uptake of 32P-end-labeled MspI or TaqI restriction fragments of the hybrid was limited to fragments entirely derived from the 4.2-kb gonococcal cryptic plasmid, indicating that DNA uptake was probably dependent on the presence of a specific DNA sequence. Since Haemophilus DNA did not inhibit transformation by the hybrid Pcr plasmid, the gonococcal DNA uptake sequence is different from the known sequence involved in homologous DNA uptake by Haemophilus spp.
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PMID:Sequence-specific DNA uptake in transformation of Neisseria gonorrhoeae. 629 60

The emergence of beta-lactamase producing strains of Haemophilus influenzae and Neisseria gonorrhoeae has required fundamental changes in the antimicrobial therapy of disease caused by these organisms. Ampicillin resistance in both organisms is caused by plasmid mediated production of TEM beta-lactamase. This enzyme is specified by a sequence of mol. wt 3.2 X 10(6) which is capable of inserting itself at multiple sites in DNA replicons without the requirement for significant base sequence homology between donor and recipient replicon. Further, it does so without requirement for conventional recombination enzymes. Analysis of beta-lactamase specifying plasmids of H. influenzae show that they generally have a molecular mass in the order of 30 X 10(6) and contain the complete TnA sequence. They are conjugative but are incapable of mobilizing smaller beta-lactamase plasmids. Previous studies have presented evidence suggesting that these plasmids may have evolved by insertion of the TnA sequence (perhaps introduced from enteric bacteria) into a phenotypically cryptic plasmid of mol. wt 27 X 10(6) resident in rare strains of H. influenzae. In this study, we review data showing a high degree of homology between the small (3--7 X 10(6) mol. wt), nonconjugative beta-lactamase specifying plasmids of N. gonorrhoeae, H. parainfluenzae and H. ducreyl and present new evidence that cryptic plasmids highly homologous to the beta-lactamase plasmids are present in many strains of H. parainfluenzae. This suggests that the small beta-lactamase specifying plasmids of H. parainfluenzae, H. ducreyi and N. gonorrhoeae may have arisen by insertion of TnA into phenotypically cryptic plasmids present in H. parainfluenzae.
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PMID:Evolution of antibiotic resistance plasmids in Neisseria gonorrhoeae and Haemophilus species. 631 45

Penicillinase-producing Neisseria gonorrhoeae strains were isolated in the Netherlands with increasing frequency during the period of 1976 to 1979. About 3% of the gonococci isolated in the first half of 1979 produced penicillinase. In contrast to the period of 1976 to 1977, most penicillinase-producing N. gonorrhoeae infections during the period of 1978 to 1979 were contracted in the Netherlands. The results of genetic and molecular studies on 80 penicillinase-producing N. gonorrhoeae strains were similar to earlier observations of others: resistance plasmids of only two sizes, 4.5 and 3.3 megadaltons (Md), occurred in penicillinase-producing N. gonorrhoeae strains, and these encoded for the TEM-1 enzyme. The 4.5-Md plasmid could be transferred to Escherichia coli when it coexisted with a plasmid of 24 Md. The latter plasmid was present in the vast majority of the strains carrying the 4.5-Md plasmid. One strain carried a cryptic 7.5-Md plasmid in addition to the commonly found 2.5-Md plasmid. Two penicillinase-producing strains of Haemophilus parainfluenzae isolated were found to carry a 3.3-Md plasmid species which was indistinguishable from the 3.3-Md gonococcal resistance plasmids. No plasmid deoxyribonucleic acid was found in two strains of penicillinase-producing Branhamella catarrhalis, and these strains produced a penicillinase different from the TEM-1 enzyme.
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PMID:Penicillinase-producing Neisseria gonorrhoeae in the Netherlands: epidemiology and genetic and molecular characterization of their plasmids. 677 87

Haemophilus influenzae isolates recovered from the genitourinary (GU) tract were shown to have a significantly different biotype distribution compared with respiratory tract isolates. Biotype IV strains were recovered more commonly from the GU tract, and most strains were non-serotypable. Antibiotic-susceptible strains isolated from the GU tract more frequently harbored plasmids of less than 10 megadaltons than did antibiotic-susceptible respiratory tract strains. One 2.8-megadalton plasmid resident in a GU tract isolate and one 1.8-megadalton plasmid resident in a respiratory tract isolate were shown to be related to the small ampicillin resistance plasmids previously described in H. influenzae, Haemophilus parainfluenzae, Haemophilus ducreyi, and Neisseria gonorrhoeae. This supports the suggestion that these ampicillin resistance plasmids originated by transposition or recombination of the ampicillin transposon (TnA) with cryptic endogenous Haemophilus plasmids.
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PMID:Haemophilus influenzae: comparison of respiratory tract isolates with genitourinary tract isolates. 698 48

Haemophilus influenzae has the ability to obtain iron from human transferrin via two bacterial cell surface transferrin binding proteins, Tbp1 and Tbp2. Although a wide array of strains have been shown to express these receptor proteins, two studies have recently identified a series of isolates which appeared to lack the ability to bind transferrin. Included in this group were the members of a cryptic genospecies of nontypeable biotype IV strains which appear to possess a tropism for female urogenital tissues and are major etiologic agents of neonatal and postpartum bacteremia due to H. influenzae. The present study employed oligonucleotide primers specific for genes encoding the Tbp proteins of a type b biotype I strain of H. influenzae to probe the genomic DNAs of isolates from the previous studies. The tbpA and tbpB genes which encode Tbp1 and Tbp2, respectively, were detected in all of the strains tested either by PCR amplification directly or by Southern hybridization analysis. All of the strains displayed a transferrin binding phenotype, and affinity isolation of receptor proteins with transferrin-conjugated Sepharose recovered Tbp1 and/or Tbp2 from 11 of 14 strains, including 2 of the nontypeable biotype IV strains. In addition, all of the strains were capable of growing on human transferrin specifically, indicating that the mechanism of iron assimilation from transferrin is functional and is not siderophore mediated. These results confirm the presence of tbp genes in all of the invasive H. influenzae isolates characterized to date, suggesting that Tbp-mediated iron acquisition is important in disease which initiates from either the respiratory or urogenital mucosa.
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PMID:Characterization of transferrin binding proteins 1 and 2 in invasive type b and nontypeable strains of Haemophilus influenzae. 755 84

In recent years, reports originating from several areas of the world have identified biotype IV strains of Haemophilus influenzae as a cause of serious urogenital, neonatal, and mother-infant infections. Preliminary analysis of a sample of biotype IV isolates found evidence for a cryptic genospecies of Haemophilus (R. Quentin, A. Goudeau, R. J. Wallace, Jr., A. L. Smith, R. K. Selander, and J. M. Musser. J. Gen. Microbiol. 136:1203-1209, 1990). Eighteen biotype IV strains assigned to the cryptic genospecies were further characterized by their rDNA restriction fragment length polymorphism patterns and genomic DNA-DNA hybridization. Isolates of the cryptic genospecies have distinctive rDNA restriction fragment length polymorphisms that differ from those of Haemophilus haemolyticus and H. influenzae. Genomic hybridization studies show that these organisms are allied with H. influenzae and H. haemolyticus and suggest a distant trifurcation of H. influenzae, H. haemolyticus, and the cryptic genospecies.
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PMID:Genetic characterization of a cryptic genospecies of Haemophilus causing urogenital and neonatal infections. 809 82


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