The genus Staphylococcus is currently composed of more than 84 recognized species and 30 subspecies [1]. Recently the genus has been reassessed and some species have been transferred to a new genus, Mammaliicoccus, which contains 5 former Staphylococcus species (Table 1) [2]. Staphylococcus sciuri, Staphylococcus fleurettii, Staphylococcus lentus, Staphylococcus stepanovicii and Staphylococcus vitulinus have been transferred to the novel genus Mammaliicoccus with Mammaliicoccus sciuri as the type species [2]. The staphylococci are divided into two distinct groups: the coagulase-positive staphylococci (CPS), such as Staphylococcus aureus and six other species, and the coagulase-negative staphylococci (CNS) ^[2][3][2,3]. They generally are part of the normal flora of mammals and birds [4], though, upon predisposing factors, they can cause mild to serious life-threatening diseases [5]. Some species are recognized as human and facultative animal pathogens, especially the coagulase-positive species though also some coagulase-negative species such as Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus lugdunensis, and Staphylococcus saprophyticus are well known facultative pathogens ^[6][7][6,7], generally implicated in nosocomial infections [8].

Antimicrobial resistance (AMR) has become a global public health issue, presenting a significant risk because it severely limits treatment options. Almost all countries, irrespective of their wealth, are facing this threat ^[9][10][9,10]. Methicillin-resistant staphylococci (MRS) pose a specific problem, as they may cause serious human and animal infections, eventually resulting in death [11]. Methicillin-resistant S. aureus (MRSA) emerged within two years after the introduction of staphylococcal beta-lactamases resistant beta-lactams, with methicillin being the first introduced [12]. Acquisition of methicillin resistance is due to integration of the staphylococcal cassette chromosome mec (SCCmec), which contains the mecA gene conferring resistance to β-lactams [13]. In 2011, A divergent mecA homologue, mecA_LGA251, later named mecC, was discovered and located in a novel staphylococcal cassette chromosome mec element, designated SCCmec type-XI [14]. The mecC was 70% identical to the mecA gene and was initially detected in 15 S. aureus isolates from dairy cattle in England [14].

Apart from S. aureus, methicillin resistance has also been discovered in many staphylococci and are named methicillin-resistant non-aureus staphylococci (MRNaS) ^[15][16][17][15,16,17]. MRNaS have been isolated from humans [18] and animals ^[17][19][17,19], and are proposed to be a potential reservoir of SCCmec elements for S. aureus [20].

The infections caused by MRSA were initially confined to hospitals and healthcare facilities and were named hospital-acquired MRSA (HA-MRSA), with sporadic infections in the community related to direct exposure to the healthcare system [21]. During the mid-1990s, new MRSA lineages emerged, which were, in general, quite susceptible to different antimicrobials and possessed the SCCmecIV [22]. The first infections with these new clones were found in native people in Australia and North America, as well as in people involved in contact sports [23]. These strains spread in the community and were likewise named community-acquired MRSA (CA-MRSA) [24]. During their evolution, they became dominant in hospitals [25]. In 2005, a new MSRA clone, ST398, was found in livestock [26], and was subsequently named LA-MRSA [27]. This clone was shown to have originated from humans and seemed to have lost host specificity while acquiring methicillin resistance [28]. Further studies showed the increasing diversity of LA-MRSA [29]. Humans in contact with livestock, mostly pigs, could be temporarily infected with these strains, suggesting a zoonotic transmission [30]; however, those clones represented little pathogenicity for humans in general [31].

There is no doubt that AMR is one of the most dangerous threats to public health in the world and it seems that the Arab countries present an ideal environment for the spread of resistant strains ^[31][32][31,36]. This could be related to several reasons, including the over/misuse of antibiotics in humans and animals, and the high mobility of animals and herders in some countries. Next to that, by large, infection control measures are absent. From a sociological standpoint, the continuous population mobilization due to socioeconomic conflicts and multiple war crises are to be taken into account ^[33][34][34,37]. Other factors involved may be the specific environmental conditions, with large deserts and limited places with water where people cluster together with their animals, as well as the intensification of animal production ^[35][38]. These specific regional characteristics may have a relevant impact on the epidemiology of MRS. The problem with methicillin resistance in staphylococci in the Arab countries, as in other parts of the world, has grown steadily ^[36]. However, its extent is currently not clear since surveillance of drug resistance is only carried out in a few Arab countries ^[34][37].