Specialized metabolites are of great interest due to their possible industrial and clinical applications. The increasing number of antimicrobial resistant infectious agents is a major health threat and therefore, the discovery of chemical diversity and new antimicrobials is crucial. Extensive genomic data from Streptomyces spp. confirm their production potential and great importance. Genome sequencing of the same species strains indicates that specialized metabolite biosynthetic gene cluster (SMBGC) diversity is not exhausted, and instead, a pool of novel specialized metabolites still exists. Here, we analyze the genome sequence data from six phylogenetically close Streptomyces strains. The results reveal that the closer strains are phylogenetically, the number of shared gene clusters is higher. Eight specialized metabolites comprise the core metabolome, although some strains have only six core gene clusters. The number of conserved gene clusters common between the isolated strains and their closest phylogenetic counterparts varies from nine to 23 SMBGCs. However, the analysis of these phylogenetic relationships is not affected by the acquisition of gene clusters, probably by horizontal gene transfer events, as each strain also harbors strain-specific SMBGCs. Between one and 15 strain-specific gene clusters were identified, of which up to six gene clusters in a single strain are unknown and have no identifiable orthologs in other species, attesting to the existing SMBGC novelty at the strain level.

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Here we report the isolation of extended-spectrum ␤-lactamase (ESBL)-and carbapenemase-producing Enterobacteriaceae from German cockroaches caught in the burn unit of Batna University Hospital in Algeria. Nine of 12 isolates harbored the bla CTX-M-15 ESBL gene. One Enterobacter cloacae isolate belonging to sequence type 528 coexpressed the bla OXA-48 , bla CTX-M-15 , and bla TEM genes. Our findings indicate that cockroaches may be one of the most dangerous reservoirs for ESBL and carbapenemase producers in hospitals.T he emergence of multidrug-resistant Enterobacteriaceae (MDRE) and their dissemination in hospitals have become a major health concern worldwide (1). The production of ␤-lactamases such as extended-spectrum ␤-lactamase (ESBL) and carbapenemase remains the main mechanism of resistance in Enterobacteriaceae (2). Algeria is now feaures among the Mediterranean countries known to be affected by the spread of CTX-M-15 type ESBL and the emergence of the phantom menace OXA-48 type carbapenemase (3, 4). Indeed, the transmission and dissemination of MDRE in hospitals are usually related to hand contact (5) and poorly sterilized instruments (6). However, cockroaches which colonize these environments may also act as potential mechanical vectors of antibiotic-resistant bacteria (7). Cockroaches are among the most prevalent pests in hospitals, where they are attracted by moisture, food, and suitable temperatures (8, 9). The medical significance of cockroaches has been largely overlooked, but it has been proven that they can harbor a number of pathogenic microorganisms with different levels of antibiotic resistance (10). Blattella germanica is the most abundant cockroach species (11), and the external surfaces and excrement of these cockroaches can contaminate food, human habitats, and hospital equipment; therefore, these insects can present a threat to human health (12).The aim of our study was to screen for broad-spectrum-cephalosporin-and carbapenem-resistant Enterobacteriaceae in B. germanica cockroaches collected from the burn unit of Batna University Hospital in Algeria and then to investigate the molecular support of ESBL and carbapenemase production.In March 2015, 10 cockroaches were randomly captured from different parts of the burn unit, including the kitchen and the guard, treatment, and patient rooms, directly in sterile containers. Samples were immobilized by freezing at 0°C for 10 min (8). Each cockroach was soaked in 5 ml of Tween 80 solution at 0.05% and vortexed vigorously for 2 min. The resulting wash was used as an external-body-homogenate sample. To remove the external body contamination, cockroaches were immersed in bleach for 2 min, in sterile physiological saline for 2 min, and then in 70% ethanol for 5 min (12). Then, each sample was washed with sterile physiological saline. Subsequently, the insect was soaked in a sterile bottle containing 5 ml of Tween 80 solution at 0.05% and then crushed inside using a sterile pestle. The triturate was then vortexed vigorously for 2 min. The resulting s...

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