2021, Sarkhoo, Eiman, Udo, Edet E., Boswihi, Samar S., Monecke, Stefan, Mueller, Elke, Ehricht, Ralf

Methicillin-resistant Staphylococcus aureus (MRSA) belonging to clonal complex 361 (CC361-MRSA) is rare among patients' populations globally. However, CC361-MRSA has been isolated with an increasing trend among patients in Kuwait hospitals since 2010. This study investigated the molecular characteristics of CC361-MRSA isolated from patients in Kuwait hospitals in 2016-2018 to understand their genetic relatedness and virulence determinants. Of 5,223 MRSA isolates investigated by DNA microarray, 182 (3.4%) isolates obtained in 2016 (N = 55), 2017 (N = 56), and 2018 (N = 71) were identified as CC361-MRSA. The CC361-MRSA isolates were analyzed further using antibiogram, spa typing and multi locus sequence typing (MLST). Most of the isolates were resistant to fusidic acid (64.8%), kanamycin (43.4%), erythromycin (36.3%), and clindamycin (14.3%) encoded by fusC, aphA3, and erm(B)/erm(C) respectively. Nine isolates (4.9%) were resistant to linezolid mediated by cfr. The isolates belonged to 22 spa types with t3841 (N = 113), t315 (N = 16), t1309 (N = 14), and t3175 (N = 5) constituting 81.3% of the spa types, four genotypes (strain types), CC361-MRSA-[V/VT + fus] (N = 112), CC361-MRSA-IV, WA MRSA-29 (N = 36), CC361-MRSA-V, WA MRSA-70/110 (N = 33) and CC361-MRSA-[V + fus] variant (N = 1). MLST conducted on 69 representative isolates yielded two sequence types: ST361 (11/69) and ST672 (58/69). All CC361-MRSA isolates were positive for cap8, agr1, and the enterotoxin egc gene cluster (seg, sei, selm, seln, selo, and selu). The tst1 was detected in 19 isolates. The immune evasion cluster (IEC) genes type B (scn, chp, and sak) and type E (scn and sak) were detected in 20 and 152 isolates, respectively. The CC361-MRSA circulating in Kuwait hospitals consisted of two closely related sequence types, ST361 and ST672 with ST672-MRSA [V/VT + fus] as the dominant genotype. The dissemination of these newly emerged clones and the emergence of linezolid resistance limits therapeutic options, as well as present significant challenges for the control of MRSA infections in Kuwait hospitals.

2021, Monecke, Stefan, Müller, Elke, Braun, Sascha D., Armengol-Porta, Marc, Bes, Michèle, Boswihi, Samar, El-Ashker, Maged, Engelmann, Ines, Gawlik, Darius, Gwida, Mayada, Hotzel, Helmut, Nassar, Rania, Reissig, Annett, Ruppelt-Lorz, Antje, Senok, Abiola, Somily, Ali M., Udo, Edet E., Ehricht, Ralf

While many data on molecular epidemiology of MRSA are available for North America, Western Europe and Australia, much less is known on the distribution of MRSA clones elsewhere. Here, we describe a poorly known lineage from the Middle East, CC1153, to which several strains from humans and livestock belong. Isolates were characterised using DNA microarrays and one isolate from the United Arab Emirates was sequenced using Nanopore technology. CC1153 carries agr II and capsule type 5 genes. Enterotoxin genes are rarely present, but PVL is common. Associated spa types include t504, t903 and t13507. PVL-positive CC1153-MSSA were found in Egyptian cattle suffering from mastitis. It was also identified among humans with skin and soft tissue infections in Saudi Arabia, France and Germany. CC1153-MRSA were mainly observed in Arabian Gulf countries. Some isolates presented with a previously unknown SCCmec/SCCfus chimeric element in which a mec B complex was found together with the fusidic acid resistance gene fusC and accompanying genes including ccrA/B-1 recombinase genes. Other isolates carried SCCmec V elements that usually also included fusC. Distribution and emergence of CC1153-MRSA show the necessity of molecular characterization of MRSA that are resistant to fusidic acid. These strains pose a public health threat as they combine resistance to beta-lactams used in hospitals as well as to fusidic acid used in the community. Because of the high prevalence of fusC-positive MRSA in the Middle East, sequences and descriptions of SCC elements harbouring fusC and/or mecA are reviewed. When comparing fusC and its surrounding regions from the CC1153 strain to available published sequences, it became obvious that there are four fusC alleles and five distinct types of fusC gene complexes reminiscent to the mec complexes in SCCmec elements. Likewise, they are associated with different sets of ccrA/B recombinase genes and additional payload that might include entire mec complexes or SCCmec elements.