The parasporal crystals ofBacillus pumilusstrain 15.1: a potential virulence factor?

ABSTRACT Nontypeable Haemophilus influenzae is an important respiratory pathogen, causing otitis media in children and lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). Immunoglobulin A1 (IgA1) protease is a well-described protein and potential virulence factor in this organism as well as other respiratory pathogens. IgA1 proteases cleave human IgA1, are involved in invasion, and display immunomodulatory effects. We have identified a second IgA1 protease gene, igaB, in H. influenzae that is present in addition to the previously described IgA1 protease gene, iga. Reverse transcriptase PCR and IgA1 protease assays indicated that the gene is transcribed, expressed, and enzymatically active in H. influenzae. The product of this gene is a type 2 IgA1 protease with homology to the iga gene of Neisseria species. Mutants that were deficient in iga, igaB, and both genes were constructed in H. influenzae strain 11P6H, a strain isolated from a patient with COPD who was experiencing an exacerbation. Analysis of these mutants indicated that igaB is the primary mediator of IgA1 protease activity in this strain. IgA1 protease activity assays on 20 clinical isolates indicated that the igaB gene is associated with increased levels of IgA1 protease activity. Approximately one-third of 297 strains of H. influenzae of diverse clinical and geographic origin contained igaB. Significant differences in the prevalence of igaB were observed among isolates from different sites of isolation (sputum > middle ear > nasopharynx). These data support the hypothesis that the newly discovered igaB gene is a potential virulence factor in nontypeable H. influenzae.

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Cytolethal Distending Toxin Gene Cluster in Enterohemorrhagic Escherichiacoli O157:H− and O157:H7: Characterization and Evolutionary Considerations

Infection and Immunity ◽

10.1128/iai.71.6.3634-3638.2003 ◽

2003 ◽

Vol 71 (6) ◽

pp. 3634-3638 ◽

Cited By ~ 89

Author(s):

Andreas Janka ◽

Martina Bielaszewska ◽

Ulrich Dobrindt ◽

Lilo Greune ◽

M. Alexander Schmidt ◽

...

Keyword(s):

Gene Cluster ◽

Virulence Factor ◽

Toxin Gene ◽

Cytolethal Distending Toxin ◽

Wild Type ◽

Potential Virulence Factor

ABSTRACT We identified a cytolethal distending toxin (cdt) gene cluster in 87, 6, and 0% of sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:H−, EHEC O157:H7, and E. coli O55:H7/H− strains, respectively. The toxin was expressed by the wild-type EHEC O157 strains and by a cdt-containing cosmid from a library of SF EHEC O157:H− strain 493/89. The cdt flanks in strain 493/89 were homologous to bacteriophages P2 and lambda. Our data demonstrate that cdt, encoding a potential virulence factor, is present in the EHEC O157 complex and suggest that cdt may have been acquired by phage transduction.

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Investigation of the antibiotic resistance and biofilm formation of Staphylococcus aureus strains isolated from gangrenous mastitis of ewes

Acta Veterinaria Hungarica ◽

10.1556/avet.2012.016 ◽

2012 ◽

Vol 60 (2) ◽

pp. 189-197 ◽

Cited By ~ 7

Author(s):

Osman Tel ◽

Özkan Aslantaş ◽

Oktay Keskin ◽

Ebru Yilmaz ◽

Cemil Demir

Keyword(s):

Staphylococcus Aureus ◽

Antibiotic Resistance ◽

Virulence Factor ◽

Resistance Genes ◽

Biofilm Formation ◽

Antibiotic Resistance Genes ◽

Penicillin G ◽

Beta Lactamase ◽

Potential Virulence Factor ◽

Amoxicillin Clavulanic Acid

In this study,Staphylococcus aureusstrains (n = 110) isolated from seven ewe flocks in Sanliurfa, Turkey were screened for antibiotic resistance and biofilmforming ability as well as for genes associated with antibiotic resistance and biofilm-forming ability. All isolates were found to be susceptible to oxacillin, gentamicin, clindamycin, cefoxitin, tetracycline, vancomycin, amoxicillin-clavulanic acid, ciprofloxacin and sulphamethoxazole-trimethoprim. The percent proportions of strains resistant to penicillin G, ampicillin and erythromycin were 27.2% (n = 30), 25.4% (n = 28) and 6.3% (n = 7), respectively. Regarding the antibiotic resistance genes, 32 (29%) isolates carried theblaZ and 8 (7.2%) theermC gene. Other resistance genes were not detected in the isolates. All isolates showed biofilm-forming ability on Congo red agar (CRA), while 108 (98.18%) and 101 (91.81%) of them were identified as biofilm producers by the use of standard tube (ST) and microplate (MP) methods, respectively. All isolates carried theicaA andicaD genes but none of them harboured thebapgene. The results demonstrated thatS. aureusisolates from gangrenous mastitis were mainly resistant to penicillins (which are susceptible to the staphylococcal beta-lactamase enzyme), and less frequently to erythromycin. Furthermore, all of theS. aureusisolates produced biofilm which was considered a potential virulence factor in the pathogenesis of staphylococcal mastitis.

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