Phylogenetic relatedness of methicillin-resistant Staphylococcus aureus isolates from the host community and Syrian refugees in Duhok Governorate based on 16S rRNA.

Objectives: The aim of the study was to investigate the genetic relatedness between methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from the host community of Duhok City and Syrian refugees based on the partial sequences of the 16S rRNA gene, and to investigate the prevalence of SCCmec and vancomycin resistance. Methods: Thirty MRSA isolates that had previously been detected and characterized were included. PCR was used for SCCmec typing, vancomycin detection, and amplification of the 16S rRNA gene for sequencing. Results: The MRSA isolates were identical and highly similar to globally published S. aureus strains, especially human nasal cavity strains. The phylogenetic tree showed that the isolates were grouped into two major groups: groups 1 and 2. Group 2 was divergent from group 1 and included isolates from the host community and Syrian refugees (new arrivals). Group 1 included isolates from the three groups, and these were genetically closely related. Most strains in both study groups were SCCmec type IVa and clustered on the same lineage of the tree. The highest rate of vancomycin resistance was found among the isolates from refugees. Conclusions: The close relationship between MRSA strains in the two study groups could be due to the geographical location of neighboring countries, which enhances the spread of MRSA strains between them.

Diversity and characterization of temperate bacteriophages induced in Pasteurella multocida from different host species.

BACKGROUND: Bacteriophages play important roles in the evolution of bacteria and in the emergence of new pathogenic strains by mediating the horizontal transfer of virulence genes. Pasteurella multocida is responsible for different disease syndromes in a wide range of domesticated animal species. However, very little is known about the influence of bacteriophages on disease pathogenesis in this species. RESULTS: Temperate bacteriophage diversity was assessed in 47 P. multocida isolates of avian (9), bovine (8), ovine (10) and porcine (20) origin. Induction of phage particles with mitomycin C identified a diverse range of morphological types representing both Siphoviridae and Myoviridae family-types in 29 isolates. Phage of both morphological types were identified in three isolates indicating that a single bacterial host may harbour multiple prophages. DNA was isolated from bacteriophages recovered from 18 P. multocida isolates and its characterization by restriction endonuclease (RE) analysis identified 10 different RE types. Phage of identical RE types were identified in certain closely-related strains but phage having different RE types were present in other closely-related isolates suggesting possible recent acquisition. The host range of the induced phage particles was explored using plaque assay but only 11 (38%) phage lysates produced signs of infection in a panel of indicator strains comprising all 47 isolates. Notably, the majority (9/11) of phage lysates which caused infection originated from two groups of phylogenetically unrelated ovine and porcine strains that uniquely possessed the toxA gene. CONCLUSIONS: Pasteurella multocida possesses a wide range of Siphoviridae- and Myoviridae-type bacteriophages which likely play key roles in the evolution and virulence of this pathogen.

Phage-inducible chromosomal islands are ubiquitous within the bacterial universe.

Phage-inducible chromosomal islands (PICIs) are a recently discovered family of pathogenicity islands that contribute substantively to horizontal gene transfer, host adaptation and virulence in Gram-positive cocci. Here we report that similar elements also occur widely in Gram-negative bacteria. As with the PICIs from Gram-positive cocci, their uniqueness is defined by a constellation of features: unique and specific attachment sites, exclusive PICI genes, a phage-dependent mechanism of induction, conserved replication origin organization, convergent mechanisms of phage interference, and specific packaging of PICI DNA into phage-like infectious particles, resulting in very high transfer frequencies. We suggest that the PICIs represent two or more distinct lineages, have spread widely throughout the bacterial world, and have diverged much more slowly than their host organisms or their prophage cousins. Overall, these findings represent the discovery of a universal class of mobile genetic elements.