Differences in genotype and virulence among four multidrug-resistant <i>Streptococcus pneumoniae</i> isolates belonging to the PMEN1 clone

We report on the comparative genomics and characterization of the virulence phenotypes of four &lt;i&gt;S. pneumoniae&lt;/i&gt; strains that belong to the multidrug resistant clone PMEN1 (Spain&lt;sup&gt;23F&lt;/sup&gt; ST81). Strains SV35-T23 and SV36-T3 were recovered in 1996 from the nasopharynx of patients at an AIDS hospice in New York. Strain SV36-T3 expressed capsule type 3 which is unusual for this clone and represents the product of an in vivo capsular switch event. A third PMEN1 isolate - PN4595-T23 - was recovered in 1996 from the nasopharynx of a child attending day care in Portugal, and a fourth strain - ATCC700669 - was originally isolated from a patient with pneumococcal disease in Spain in 1984. We compared the genomes among four PMEN1 strains and 47 previously sequenced pneumococcal isolates for gene possession differences and allelic variations within core genes. In contrast to the 47 strains - representing a variety of clonal types - the four PMEN1 strains grouped closely together, demonstrating high genomic conservation within this lineage relative to the rest of the species. In the four PMEN1 strains allelic and gene possession differences were clustered into 18 genomic regions including the capsule, the blp bacteriocins, erythromycin resistance, the MM1-2008 prophage and multiple cell wall anchored proteins. In spite of their genomic similarity, the high resolution chinchilla model was able to detect variations in virulence properties of the PMEN1 strains highlighting how small genic or allelic variation can lead to significant changes in pathogenicity and making this set of strains ideal for the identification of novel virulence determinant

Virulence phenotypes of low-passage clinical isolates of Nontypeable Haemophilus influenzae assessed using the chinchilla laniger model of otitis media

<p>Abstract</p> <p>Background</p> <p>The nontypeable Haemophilus influenzae (NTHi) are associated with a spectrum of respiratory mucosal infections including: acute otitis media (AOM); chronic otitis media with effusion (COME); otorrhea; locally invasive diseases such as mastoiditis; as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. These diverse clinical and genotypic findings suggest that each NTHi strain possesses a unique set of virulence factors that contributes to the course of the disease.</p> <p>Results</p> <p>The local and systemic virulence patterns of ten genomically characterized low-passage clinical NTHi strains (PittAA – PittJJ) obtained from children with COME or otorrhea were stratified using the chinchilla model of otitis media (OM). Each isolate was used to bilaterally inoculate six animals and thereafter clinical assessments were carried out daily for 8 days by blinded observers. There was no statistical difference in the time it took for any of the 10 NTHi strains to induce otologic (local) disease with respect to any or all of the other strains, however the differences in time to maximal local disease and the severity of local disease were both significant between the strains. Parameters of systemic disease indicated that the strains were not all equivalent: time to development of the systemic disease, maximal systemic scores and mortality were all statistically different among the strains. PittGG induced 100% mortality while PittBB, PittCC, and PittEE produced no mortality. Overall Pitt GG, PittII, and Pitt FF produced the most rapid and most severe local and systemic disease. A post hoc determination of the clinical origins of the 10 NTHi strains revealed that these three strains were of otorrheic origin, whereas the other 7 were from patients with COME.</p> <p>Conclusion</p> <p>Collectively these data suggest that the chinchilla OM model is useful for discriminating between otorrheic and COME NTHi strains as to their disease-producing potential in humans, and combined with whole genome analyses, point the way towards identifying classes of virulence genes.</p

Strain-specific virulence phenotypes of Streptococcus pneumoniae assessed using the Chinchilla laniger model of otitis media.

Streptococcus pneumoniae [Sp] infection is associated with local and systemic disease. Our current understanding of the differential contributions of genetic strain variation, serotype, and host response to disease phenotype is incomplete. Using the chinchilla model of otitis media [OM] we investigated the disease phenotype generated by the laboratory strain TIGR4 and each of thirteen clinical strains (BS68-75, BS290, BS291, BS293, BS436 and BS437); eleven of the thirteen strains have been genomically sequenced.For each strain 100 colony forming units were injected bilaterally into the tympanic bullae of 6 young adult chinchillas under general anesthesia. All animals were examined daily for local and systemic disease by a blinded observer. Pneumatic otoscopy was used to evaluate local disease, and behavioral assessments served as the measure of systemic disease. Virulence scoring was performed using a 4-point scale to assess four clinical parameters [severity and rapidity of local disease onset; and severity and rapidity of systemic disease onset] during a 10-day evaluation period. Highly significant variation was observed among the strains in their ability to cause disease and moribundity.As expected, there was a significant correlation between the rapidity of systemic disease onset and severity of systemic disease; however, there was little correlation between the severity of otoscopic changes and severity of systemic disease. Importantly, it was observed that different strains of the same serotype produced as broad an array of disease phenotypes as did strains of different serotypes. We attribute these phenotypic differences among the strains to the high degree of genomic plasticity that we have previously documented

Virulence phenotypes of low-passage clinical isolates of nontypeable Haemophilus influenzae assessed using the chinchilla laniger model of otitis media.

BACKGROUND: The nontypeable Haemophilus influenzae (NTHi) are associated with a spectrum of respiratory mucosal infections including: acute otitis media (AOM); chronic otitis media with effusion (COME); otorrhea; locally invasive diseases such as mastoiditis; as well as a range of systemic disease states, suggesting a wide range of virulence phenotypes. Genomic studies have demonstrated that each clinical strain contains a unique genic distribution from a population-based supragenome, the distributed genome hypothesis. These diverse clinical and genotypic findings suggest that each NTHi strain possesses a unique set of virulence factors that contributes to the course of the disease. RESULTS: The local and systemic virulence patterns of ten genomically characterized low-passage clinical NTHi strains (PittAA - PittJJ) obtained from children with COME or otorrhea were stratified using the chinchilla model of otitis media (OM). Each isolate was used to bilaterally inoculate six animals and thereafter clinical assessments were carried out daily for 8 days by blinded observers. There was no statistical difference in the time it took for any of the 10 NTHi strains to induce otologic (local) disease with respect to any or all of the other strains, however the differences in time to maximal local disease and the severity of local disease were both significant between the strains. Parameters of systemic disease indicated that the strains were not all equivalent: time to development of the systemic disease, maximal systemic scores and mortality were all statistically different among the strains. PittGG induced 100% mortality while PittBB, PittCC, and PittEE produced no mortality. Overall Pitt GG, PittII, and Pitt FF produced the most rapid and most severe local and systemic disease. A post hoc determination of the clinical origins of the 10 NTHi strains revealed that these three strains were of otorrheic origin, whereas the other 7 were from patients with COME. CONCLUSION: Collectively these data suggest that the chinchilla OM model is useful for discriminating between otorrheic and COME NTHi strains as to their disease-producing potential in humans, and combined with whole genome analyses, point the way towards identifying classes of virulence genes.</p

Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media-9

<p><b>Copyright information:</b></p><p>Taken from "Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media"</p><p>http://www.biomedcentral.com/1471-2180/7/56</p><p>BMC Microbiology 2007;7():56-56.</p><p>Published online 14 Jun 2007</p><p>PMCID:PMC1914350.</p><p></p>las inoculated with the 10 clinical NTHi strains. X-axis = the clinical NTHi strains (PittAA-PittJJ, left to right); Y-axis = the otologic clinical score based upon the criteria in Table 1

Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media-5

<p><b>Copyright information:</b></p><p>Taken from "Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media"</p><p>http://www.biomedcentral.com/1471-2180/7/56</p><p>BMC Microbiology 2007;7():56-56.</p><p>Published online 14 Jun 2007</p><p>PMCID:PMC1914350.</p><p></p>= time in days following inoculation; Y-axis percentage of surviving animals

Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media-8

<p><b>Copyright information:</b></p><p>Taken from "Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media"</p><p>http://www.biomedcentral.com/1471-2180/7/56</p><p>BMC Microbiology 2007;7():56-56.</p><p>Published online 14 Jun 2007</p><p>PMCID:PMC1914350.</p><p></p> develop their maximum (most severe) otologic score – regardless of what that score was. X-axis = the clinical NTHi strains (PittAA-PittJJ, left to right); Y-axis = the days post inoculation that moderate or worse local disease developed

Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media-1

<p><b>Copyright information:</b></p><p>Taken from "Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media"</p><p>http://www.biomedcentral.com/1471-2180/7/56</p><p>BMC Microbiology 2007;7():56-56.</p><p>Published online 14 Jun 2007</p><p>PMCID:PMC1914350.</p><p></p> develop their maximum (most severe) otologic score – regardless of what that score was. X-axis = the clinical NTHi strains (PittAA-PittJJ, left to right); Y-axis = the days post inoculation that moderate or worse local disease developed

Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media-6

<p><b>Copyright information:</b></p><p>Taken from "Virulence phenotypes of low-passage clinical isolates of Nontypeable assessed using the model of otitis media"</p><p>http://www.biomedcentral.com/1471-2180/7/56</p><p>BMC Microbiology 2007;7():56-56.</p><p>Published online 14 Jun 2007</p><p>PMCID:PMC1914350.</p><p></p>g of distributed or non-core genes [26,28] which are defined as the set of genes not universally present among all strains of the species. The figure compares 15 NTHi strains, which include 9 of the strains phenotyped in the current study (PittDD was omitted due to incomplete genomic data and PittFF and PittGG collapse to a single strain using this method) and the laboratory strain Rd. The sequence for the 86028NP strain has been previously published [18], and the unannotated sequences for the R2866 and R2846 NTHi strains were obtained from Genbank (accession #s NZ_AADP00000000, and NZ_AADO00000000, respectively) and used with permission of the depositing authors. The X-axis lists the number of genic differences between strains; y-axis lists the strains. Strain 86028NP is a nasopharyngeal (NP) isolate obtained from a patient suffering from OM; R2866 is an invasive strain; CHSHi22121 is an NP isolate from a well child; R2846 is an COME isolate; CGSHiR3021 and CGSHi22421 are NP isolates from healthy children; and CHSHi3655 is an OME strain