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BackgroundLivestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported.ObjectivesTo determine the prevalence of Staphylococcus aureus (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates.MethodsOne thousand twenty-two SA isolates (761 MSSA, 261 MRSA) recovered from blood cultures during 6–12 months in 17 Spanish hospitals (2018–2019) were studied. CC398 lineage identification, detection of spa-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing.ResultsForty-four CC398-MSSA isolates (4.3% of SA; 5.8% of MSSA) and 10 CC398-MRSA isolates (1% of SA; 3.8% of MRSA) were detected. Eleven spa-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent spa-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin–inducible-resistant/erm(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km2) (p = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately spa-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (p < 0.005).ConclusionCC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers.

Aims To determine the Staphylococcus aureus carriage rate in wild mammals in Aragon, northern Spain, to analyse their antimicrobial resistance phenotype/genotype and to characterize the recovered isolates. Methods and Results Nasal and rectal swabs of 103 mammals were collected in Aragón during the period 2012–2015. Antimicrobial susceptibility, the presence of antimicrobial resistance genes and virulence factors were investigated. Molecular characterization was carried out by spa, MLST, agr and SCCmec. Staphylococcus aureus were recovered from 23 animals (22%). Four of the 23 S. aureus were methicillin‐resistant S. aureus (MRSA). Three MRSA were mecC‐positive and were isolated from European rabbits and were typed as t843 (ascribed to CC130). The remaining MRSA was a mecA‐carrying isolate from European hedgehog, typed as ST1‐t386‐SCCmecIVa‐agrIII and it harboured the blaZ, erm(C), ant(6)‐Ia and aph(3´)‐IIIa resistance genes. A high diversity of spa‐types was detected among the 19 methicillin‐susceptible S. aureus isolates, which showed high susceptibility to the antimicrobials tested. The tst gene and different combinations of staphylococcal enterotoxins were found. Conclusions Staphylococcus aureus were detected in nasal and rectal samples of wild mammals. Wild rabbits could be a reservoir of mecC‐MRSA. Significance and Impact of the Study This work provides information on the presence and characteristics of S. aureus from mammals in a defined geographic region in Spain.

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This study evaluated the occurrence of extended-spectrum β-lactamases (ESBL) and associated resistance genes, integrons, and plasmid types as well as the genetic relatedness of enterobacterial isolates in the wastewater treatment plant (WWTP) of La Charguia, Tunis City (Tunisia). One-hundred water samples were collected at different points of the sewage treatment process during 2017–2019. Antimicrobial susceptibility was conducted by disc-diffusion method. blaCTX-M, blaTEM and blaSHV genes as well as those encoding non-β-lactam resistance, the plasmid types, occurrence of class1 integrons and phylogenetic groups of Escherichia coli isolates were determined by PCR/sequencing. Genomic relatedness was determined by MLST for selected isolates. Fifty-seven ESBL-producer isolates were recovered (47 E. coli, eight Klebsiella pneumoniae, one of the Citrobacter freundii complex and one of the Enterobacter cloacae complex). CTX-M-15 was the most frequently detected ESBL, followed by CTX-M-27, CTX-M-55 and SHV-12. One E. coli isolate harboured the mcr-1 gene. The following phylogroups/STs were identified among ESBL-producing E. coli isolates: B2/ST131 (subclade-C1), A/ST3221, A/ST8900, D/ST69, D/ST2142, D/ST38, B1/ST2460 and B1/ST6448. High number of isolates harboured the class 1 integrons with various gene cassette arrays as well as IncP-1 and IncFIB plasmids. Our findings confirm the importance of WWTPs as hotspot collectors of ESBL-producing Enterobacteriaceae with high likelihood spread to human and natural environment.

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