**5. Discussion**

*Staphylococcus aureus* is one of the most important and adaptable human pathogens, causing most often skin and soft tissue infections, although it can cause any organ and organic system infection as well as infections related to toxin production [29]. Colonisation is important step in pathogenesis of infections caused by *S. aureus*. Approximately 20–30% of overall population is persistently colonised by *S. aureus*, with verified colonisation at nasal mucosa [30]. This study microbiologically analyses 4341 different biological specimens from out of hospital respondents. *Staphylococcus aureus* is isolated in 2279 specimens, with prevalence of 52,5%. Out of 2279 identified *Staphylococcus aureus*, methicillin resistance was shown in 653 isolates proved by use of phenotype methods, thus MRSA prevalence was 28,7%. Considering the use of MRSA prevalence as an indicator of success in conducting infection control programme, there are series of data from various geographical areas that point to high variability of MRSA prevalence in the whole world. European research show high variability in MRSA prevalence results. Thus, percentage of MRSA in Scandinavian countries and Netherlands is less than 1%, while prevalence in Spain is more than 50% [31]. At latest, growth of bacterial isolates number resistant to methicillin becomes serious clinical and epidemiological problem. Introducing methicillin into clinical practice in 1961, MRSA soon becomes one of the main intra-hospital problems around the world. Nowadays, MRSA still holds primate in hospital environment, and in the last few years in out of hospital environments as well. Namely, in the nineties of the last century, the problem of out of hospital MRSA (Community-acquired methicillin-resistant *Staphylococcus* 

#### *Distribution and Molecular Detection of Methicilin-Resistant* Staphylococcus aureus *DOI: http://dx.doi.org/10.5772/intechopen.98655*

*aureus* or CA-MRSA) arises, in many features different from hospital MRSA strains. *Staphylococcus aureus* resistant to methicillin is placed highly in modern microbiology and infection control procedures. Recent studies show change in microbiology of MRSA as well as its limitation to hospital environment so the infection can appear in general population [29]. CA-MRSA strains become important health issue connected with high morbidity and mortality in general population [32].

In our study, we selected representative sample of 100 MRSA strains, eliminating "copy" strains (strains of the same patient from different places and those repeated ones), by random choice method, trying to follow the dynamics and equal representation through individual months of research period. In our study, 41% cases confirmed presence of the pathogen in the nasal, and 35% samples isolated *S.aureus* in skin smear. Creech et al. confirmed colonisation of nasal mucosa in paediatric cases with *S.aureus* in 35% cases, and in 9% cases they bore nasal MRSA [33]. Male sex was positive to MRSA in 49%, while females were positive in 51% of analysed MRSA specimens. In Farr et al. study [34] has shown that females were highly represented in verified CA-MRSA infections. The same study shows the greatest number of out of hospital infections in females aged 18–44. In our study average age was 10,9 (±18,7). Those results could be explained by high number of new-borns analysed in our research. Anamnestic data in epidemiology questionnaire about eventual hospitalisation within a year prior to beginning of the study has shown that 59% of respondents had been hospitalised at some clinical department, while the greatest percentage had been hospitalised at maternity department of the clinic (86.4%), adding to the data of high new-borns representation in the research. However, the German study done at in-hospital and out-of-hospital patients showed high prevalence of CA-MRSA in patients with hospitalisation data or prolonged stay at special purpose facilities (nursing homes) [35]. According to the definition of CDC, as well as numerous modifications of the definition, there are epidemiological circumstances among risk factors in appearance of out-of-hospital MRSA infection. Having that in mind, we analysed series of general prior data and the analysis followed the criteria for differentiating in-hospital from out-of-hospital MRSA. The data showed that only 6% of respondents had undergone surgeries in the prior year, while 2% of positive respondents have used some invasive apparatus. Pets had earlier been identified as the source and transmitters of MRSA infections to humans in contact [36].

Analysing data of epidemiological questionnaire it shows that 10% of the respondents keep a pet, 3% have had documented MRSA infection before, 8% have had contact with MRSA carrier, while 13% practiced collective sports. Resistance development becomes issue of priority, and the follow up system for resistance measurement in relevant data, according to which antibiotics would be given by recommendations to lower the resistance, e.g. try to stop or slow down the development of new resistance, has been established.

Data on resistance in the close by environment have to be basis for empirical therapy development, so it can be more successful in every single patient treatment, as well as efficient in spreading resistant types in the community.

For those reasons it is necessary to have local epidemiological data on sensitivity of out-of-hospital strains and specific hospital close at hand, due to variation of bacterial resistance level between hospital centres in different countries, between centres of the same country, as well as between hospital wards and departments of the same centre.

*Staphylococcus aureus* is a microorganism that developed resistance mechanisms to all antibiotics available for treating infections caused by staphylococci. The most important among those antibiotics that *S. aureus* developed resistance to, are the ones indispensable in therapy schemata for infection caused by staphylococci treatment and resistance mechanisms that mark antibiotics era. Penicillin as the

medicine of first choice for staphylococci infection treatment is almost abandoned, while the remaining number of isolates sensitive to penicillin activity is 20% by some studies [37].

According to the data extracted by isolate testing in disc – diffusion method, resistance to penicillin, methicillin (oxacilin) and cefoxitin showed all MRSA strains. Among isolates of the collection, resistance to vancomycin, linezolid, rifampicin, sulfamectasole – trimethoprim and fusidine acid was not shown. For vancomycin the sensitivity out of inhibition zone less than 14 mm in disc – diffusion method according to CLSI standards was not confirmed [38].

Resistance to macrolides is 68%, while to clindamycin it is significantly less and in amount of only 5%.

Resistance to gentamicin is 5% while to ciproflaxcin is 4%.

It is well-known that great percentage of hospital MRSA strains is resistant to quinolone, in total 90%. Similar results are gathered in in the research in the area of Republic of Croatia (91%), where the progressive test to quinolone has been followed in the last 20 years [39].

In the world resistance phenomenon among *S.aureus* strains context, exact and early assessment of resistance is of key importance in infection caused by *S.aureus* prognosis.

Although many phenotype methods have been developed to achieve fast methicillin resistance detection, lack of these methods is lessened sensitivity, which in the end cannot ensure appropriate and timely treatment of all patients infected by MRSA.

Several studies have shown that revelation of *mec*A gene is the "golden standard" method for diagnosing MRSA in microbiological laboratories [40].

However, not all laboratories, especially in transition countries such as ours is, have the necessary equipment and educated stuff for establishing molecular techniques. Thus, the need for fast, exact and economically profitable identifying MRSA strains by phenotype methods appeared [41].

As for disc diffusion tests for MRSA detection, sensitivity of oxacilin disc diffusion test and cefoxitin disc diffusion test was 100%, while specificity was 96% and 98%.

Rao Venkatakrishna et al. also found high sensitivity and specificity of oxacilin DD and DD Cefoxitin test in MRSA detection [42].

Chromogenic surface use (ChromID) has shown 100% specificity and sensitivity. Morris et al. in their study compared chromogenic surfaces and showed sensitivity for ChromID 93% [43].

In some authors' studies [44] E-test in MRSA detection has been used as the golden standard and its advantages in the sense of conducting, as well as precision that approaches those of molecular methods PCR, *mec*A detection, have been proven. In our study we have also shown 100% sensitivity and specificity for E-test. Also, for latex agglutination test we have confirmed identical results. Ahmad has proven superiority of the test as the alternative method MRSA detection in his study [45].

After conducting phenotype methods, we have examined MRSA strains by molecular typing methods, and by analysis of data gathered in that way, we have come to interesting clinical and epidemiological findings.

With all isolates included in the research after detecting methicillin resistance by phenotype methods, they were subjected to molecular methods by which the presence *mec*Agene was tested. All examined isolates were positive to *mec*Agene, according to the claim that for *mec*Agene identification, polymerase chain reaction (PCR) is considered the golden standard [40].

*Distribution and Molecular Detection of Methicilin-Resistant* Staphylococcus aureus *DOI: http://dx.doi.org/10.5772/intechopen.98655*

By method *spa*-typing, developed by Freney et al. [46], based on sequencing polymorph region X gene protein A *Staphylococcus aureus* (*spa*), we typed 29 out of our 100 types. We had seven various *spa*-types, from which the most represented t008 16/29 (52,2%), t1179 5/29 (17,2%), t10807 3/29 (10,3), t2674 2/29 (69%), t041 1/29 (3,4%), t919 1/29 (3,4%), t2187 1/29 (3,4%). If we compare it with relative global frequency of appearance for single *spa*-types by Ridom Spa Basa, we can notice that t008 is globally represented in 6,32%. Spa t008 is present in the countries such as Australia, Austria, Bulgaria, Canada, Croatia, Check Republic, Denmark, Estonia, Finland, Germany, Hungary, Israel, Norway, Poland, Portugal, Spain, Great Britain, Switzerland and Sweden. The *spa* type is found in sequence types ST-8, ST-247, ST-250 and ST-254, and placed in CC8, Northern German MRSA, USA300 ORSA IV and Archaic/Iberian clonal complex.

In this study t041 was represented 3,4%, while globally it is less represented with only 0,31% (Austria, Belgium, B&H, Croatia, Check Republic, Denmark, France, Germany, Hungary, Island, Ireland, Italy, Netherlands, Norway, Slovenia, Sweden and Switzerland), in sequence types ST-111 i ST-228, placed in CC5 and Southern German MRSA clonal complexes.

Representation of t919 in our study is the same as t041 (3,4%), and it appears in Austria, Germany, Norway and Sweden, with globally significantly less representation of 0,01%.

In our study we had four, so far unknown, *spa* types, and it can be explained by polymorph region X consisting of 24 base pairs of repeating fragments.

In our analysis the SCC*mec* results of typification have shown dominance of SCC*mec* type IV (86%), typical for out-of-hospital population. It is necessary to emphasize there is appearance trend for SCC*mec* type IV inside hospital population, with the tendency of shifting SCC*mec* type I and dominant Iberian clone so far characteristic for in-hospital environment. SCC*mec* typing of strains included in our research we have proven that da SCC*mec* type I is seen in total of 4% strains, while SCC*mec* type V is seen in very small percentage (1%) in the examined strains. Valsesia et al. [47] have recently confirmed that SCC*mec* type IV and V was registered in examined population in the amount of 87% cases, while SCC*mec* type I and II appeared only sporadically, and SCC*mec* type III was completely absent in out-ofhospital population. In our analysis we have not confirmed any case of SCC*mec* type II or III. Those results are in accordance with our results, except that SCC typing of strains included in the study has not shown presence of SCC*mec* type V types.

Previous studies have indicated that HA-MRSA infections are mainly caused by multiresistant strains carrying SCC*mec* type I, II or III, but rarely SCC mec type IV. On the other hand, CA-MRSA strains carrying SCC*mec* type IV, V or VII, are usually sensitive to majority of un-β-lactam antibiotics, although series of studies indicate spreading CA-MRSA strains in hospital centres and consequently taking place of traditional HA-MRSA strains [48, 49].

Our study indicates possible existence of new combinations of SCC*mec* fragments and ccr genes evolving by recombining already described segments, and by completely new SCC*mec* types, due to genome *S.aureus* susceptibility to dynamic changes, changes of genetic parts inside the species as well as species typical for *S.aureus.* This conclusion is based on presence of 9% atypical strains.

In our collection of strains subjected to molecular analysis, all MRSA isolates have been tested to presence Panton-Velentine leukocidin (PVL) toxin. Number of PVL-positive MRSA was 23 isolates, while one isolate was atypical.

Some studies in which virulence factors with PVL of in-hospital and out-ofhospital MRSA were examined at the same time and it is discovered that less than 5% MRSA isolates are SCCmec I, II and III PVL positive, while 40–90% MRSA

SCCmec type IV contains PVL gene. [50]. CA-MRSA can represent serious problem for public health due to distribution of strains with potential to produce PVL toxin. Presence of genes coding Panton-Valentine leukocidin is important marker of virulence as well as determinant of clinical consequences of infections caused by PVL positive types which are far heavier than PVL negative *S. aureus* infections. Cocchi et al. [51] in their study showed the transmission of PVL -positive CA-MRSA, member of Southwest Pacific clone (SWP) with epidemic capacity. The same study shows transmission from father with recurrent skin and subcutaneous tissue infections, over mother with nasal colonisation, to their child with symptoms of necrotising pneumonia. These data indicated that recurrent skin infections, usually not given great clinical importance, can represent serious threat in development of severe clinical picture of the carrier with possibility of further transmission PVL positive causer.

However, the role of positive MRSA strains in predicting possible severe clinical manifestations for the carrier still remains undefined.

CA-MRSA is linked to the production of Panton-Valentin leukocidin. Probably the PVL is direct virulence factor in staphylococci necrotising pneumonia [52], while its role in skin and soft tissues infection remains controversy.

There is epidemiological connection between MRSA and PVL, especially in the USA where USA300 clone dominates which is PVL positive. But counterargument to the attitude, at the same time confirming still undefined role of PVL as virulence marker in prediction of clinical infection manifestations, is the fact that there are several types PVL negative with the same clinical outcome that this toxin cannot be taken as universal marker of CA-MRSA. In the conducted analysis on 100 MRSA isolates, it is confirmed that 23 isolates SCCmec type IV containing gene z PVL, one atypical isolate while there were 76 PVL negative isolates of various SCCmec types, but with dominance of type IV. By examining isolates origin we established that 11 PVL positive PVL isolates were from skin area, 8 from nasal mucosa, 2 from pustule smear, while others were represented by 1 PVL positive isolates from different corporal regions (sound conductor, wound smear).

In Great Britain, according to the National Reference Laboratory data, genes coding PVL are present in less than 2% of clinical isolates *S. aureusa*, whether MSSA or MRSA [52]. While PVL is currently accepted as important factor for *S. aureus* virulence, the latest research give preference to alternative virulence factors such as arginine catabolic mobile element (ACME), α toxin, regulatory genes coding expression, and newly described peptides.

PVL role is still very important, primarily due to fact it represents important marker in screening virulent *S.aureus* strains.

PFGE is genetic typing method used as means of molecular – epidemiological study of genetic variants of *S. aureus* and other numerous bacterial pathogens. For its highly discriminating capacity PFGE is considered golden standard for local epidemics of bacterial infections [53]. Combination of molecular typing methods (PFGE, mecA, SCC*mec* and MLST) with epidemiological and clinical data enable revelation of MRSA groups and their appearance, thus ensuring application of rational, appropriate, infection control measures [54]. Also, this study has enabled detection of MRSA groups in limited geographical area by applying methods of molecular typing so it can represent basis for similar studies on broad area and enable application of this region into European MRSA infection control network.

Comparing PFGE analysis results, by criteria of Tenover et al.(28), applying cutoff similarities 80%, our study has shown that most of the isolates is classified into two larger groups, indicating clonal connection and genetic similarity of isolates. Dendogram contains 5 groups, marked alphabetically from A to E.

#### *Distribution and Molecular Detection of Methicilin-Resistant* Staphylococcus aureus *DOI: http://dx.doi.org/10.5772/intechopen.98655*

PFGE analysis of profile isolates by computer system GelCompar isolates are grouped in similarity groups, inside which similarity between isolates is 80% and more. Thus we had results in five groups, marked alphabetically from A to E. Most of the isolates fell into two most numerous groups, C and D.

Group A contains 3 isolates, falling into SCC*mec* type IV. This group had no PVL positive isolates.

Group B contains four isolates, with 3 isolates belonging to SCCmec type I, while one belongs SCC*mec* type IV. This group does not have PVL positive isolates.

Group C contains 60 isolates, and represents the most numerous group in our PFGE analysis. All isolates of the group belong to SCC*mec* type IV. This group had 28,33% (17) PVL positive isolates.

Group D has had 27 isolates, three of them atypical and the rest of them also fall into SCC*mec* type IV. In this group only two isolates were PVL positive.

Group E has had 3 isolates, belonging to SCC*mec* type I, IV and V. These three isolates were not PVL positive.

Three PFGE types are single genotypes, with two of them SCC*mec* IV, while one is atypical.

Among mostly used definitions CA-MRSA that take into account epidemiological data, as well as genetic origin of isolates are modified definitions of the CDC. In cases of suspicion to CA-MRSA the first step is to eliminate any connection to hospitals and hospital system, because the connection for such isolates places them into HA-MRSA species [55].

Due to the fact it is necessary to have molecular analysis for the types aiming to avoid classifying MRSA strains into CA or HA MRSA strains based on epidemiological data, for it might lead to possibility of crosswise mistakes.

Concerning the received results indicating presence of isolates SCC*mec* type IV and with respondents of paediatric age with positive epidemiological data of hospital environment contact, traditional division to in-hospital and out-of-hospital MRSA is questionable and demands further revision.

Prevalence of "real" CA MRSA strains in general population broadly varies in different geographical areas. In meta analysis, Salgado et al. [56], showed prevalence in amount of 1,3% for MRSA colonisation in community. However, it must be pointed out that most of the people colonised by MRSA strains, had risk factors connected to hospitalisation.

After excluding these patients prevalence of "real" CA-MRSA colonised was 0,2%, responding to the prevalence of the study (0,13%).

About presence of CA MRSA in Bosnia and Herzegovina there is not enough data. There are several genotyping isolate methods *S.aureus* for epidemiological research. However, Harbarth et al. [57] still give advantage to molecular methods of MRSA identification comparing to standard cultivation methods. Anyway, length of the procedure and the need for specialised laboratories still represents limiting factor for broad use of molecular analysis.

Earlier reports on CA-MRSA strains describes appearance of new strains in patients with the lack of traditional epidemiological risk factors for MRSA infection and/or colonisation. Those patients with CA-MRSA infection are very often of younger age, with minimum comorbidities and negative epidemiological data of hospital environment contact, comparing to patients with infections caused by HA-MRSA strains. Furthermore, different socio-economic characteristics related to CA-MRSA infections, including ethnical background and socio-economic status.

Recently, [58] however, with the growth of CA-MRSA prevalence, epidemiological difference between these and HA-MRSA types became less defined, concerning numerous reports of hospital epidemics caused by CA-MRSA types.

CA-MRSA is more often defined as cause of infections arising at hospital environment and infections connected to hospital environment. On the other hand, hospital clones are described as cause of infections in general population, indicating the fact that some clones are capable of successful barrier crossing between hospitals and general population [59].

In spite of its clinical importance, multicentric research of the entire area of Bosnia and Herzegovina for prevalence and epidemiology of MRSA as the cause of infections in general population, has not been conducted. This imposes the necessity for national monitoring of spreading and presence of these types.

### **6. Proposal for algorithm of treatment CA-MRSA infection**

The first choice for empirical antimicrobial medication depends on MRSA prevalence in the community, type and severity of infection. Vancomycin should be prescribed in cases of severe infections [60], while microbiological data is available, in areas where similar infections of outpatient MRSA strains were documented. Also, it is necessary to prescribe vancomycin in cases when it is known that patient had been colonised by MRSA strain, or is intravenous addict or when MRSA infection risk factors are included. In the last ten years skin and soft tissue infections caused by CA-MRSA have reached epidemic level. The key in their treatment is surgical care, incision and drainage, in avoiding further tissue destruction; with empirical application of antibiotics modified according to microbiological findings. In the areas of low prevalence CA-MRSA and in treatment of mild infections therapy should be started with some penicillin antibiotics resistant to penicillinase or the first generation of cephalosporins [61]. The carrier selection, if undertaken, is important in process of hospitalisation, in the open community it is impossible to be carried out. However, the follow up for discharged patients and control of their laboratory diagnostics with MRSA sensitivity examination, is more important than ever before. Screening can reduce MRSA incidence during hospitalisation admission process. MRSA eradication or decolonisation by topical application of mupirocin or cotrimaxazole are used with various success, and some studies show that sulfamethoxazole-trimethoprim in available oral antibiotics has the fastest bacteria impact [62]. Due to fast resistance development, decolonisation of all known carriers is not recommended [63].

Due to high morbidity and mortality connected to staphylococci isolates coding PVL, the selection of carriers and decolonisation by muciprocin is recommended with people having recurring abscesses despite antimicrobial therapy and their contacts if they have MRSA isolated in nasal vestibule.

PVL toxin and better understanding of toxin role in pathogenesis of CA-MRSA infections can have therapy implications. Some studies have shown that intravenous immunoglobulin use has benefits in positive treatment outcomes in shock therapy [64]. PVL neutralisation as well as other toxins by intravenous immunoglobulin is shown in vitro [65]. Based on the prevalence CA-MRSA of 0,13%, where none of the isolates caused severe infection, we estimate that empirical therapy for outpatient pneumonia treatment does not need any modification by adding antibiotics with impact on MRSA isolate, such as vancomycin.

#### **6.1 Detection algorithm/treatment of outpatient MRSA**

Having in mind the fact that in the world and Europe number of outpatient MRSA increases, in diagnostic and therapeutic approach it must be taken into account that it is MRSA strain.

#### *Distribution and Molecular Detection of Methicilin-Resistant* Staphylococcus aureus *DOI: http://dx.doi.org/10.5772/intechopen.98655*

Good sampling and choice for microbiological testing, (smear, wound aspirate in the case of localised infection and blood in the case of system infection), fast detection of MRSA in microbiological laboratory, as well as the result of sensitivity to adequate nonbetalactam antibiotics may contribute to adequate infection treatment and timely measure taking in infection control, aiming at reducing spreading of very adaptable outpatient MRSA strains in ambulances and hospital environment.

Diagnosis CA-MRSA infection should be considered with seriously ill young people who previously had had symptoms similar to influenza, pneumonia disease with hemoptysis symptoms, high febrility, leucopenic and and hypotensive. Those symptoms are signal to life threatening infection, necrotising pneumonia, and septic shock and, in consequence, even death outcome.

Important ways of presenting CA-MRSA infections are skin infection, with developing abscess, furuncle, carbuncle, without drainage infections progress to fasciitis, deep infections of soft tissues, after which, in case of recovery, tissue deformities are left.

Epidemiological definition and connection to hospital stay lose in importance because it is not unusual for typical CA-MRSA to cause epidemics in hospital wards [66].

As the first step in successful treatment the selection of suitable sample for microbiological testing is recommended. In cases of severe skin and subcutaneous tissue infections taking abscess aspirates or deep subcutaneous change will also have therapeutic effect.

In case of suspicion to necrotic pneumonia, blood sample usually contains cause, while sample from respiratory system is desirable.

For cause diagnostics of mild skin change, it is enough to take skin smear. Depending on sat down of infection, for sampling, standard rules of microbiological testing apply.

For treatment outcome it is important to apply suitable antimicrobial medication and in the case of suspicion to MRSA infection the confirmation is of extreme value.

With application of antistaphylococci antibiotics, penicillin or cephalosporin, skin and subcutaneous tissue infection and fascia it is necessary to surgically treat, incise and debride abscess.

By standard processes of isolation and detection of *S.aureus*, after which the testing is undertaken for isolates sensitivity to oxacilin/cephoxitin and the result due is in 48 hours later.

A lot better time frame is given by molecular MRSA detection based on PCR method. The latest PCR methods do not use amplification mecA as proof for MRSA, because there is a possibility of getting falsely positive results by amplification *mec*A gene coagulaze-negative staphylococci contaminating the sample. IDI-MRSA (Infecto Diagnostic, Canada), GenoType MRSA Direct (Hain Lifescience, Germany), detect part of orfX gene, specific For*s. aureus* and adjacent part of SCC*mec* chromosome region. In that way one PCR reaction detects MRSA in unsterile samples. Results are available in 24 hours.

Small number of routine laboratories in Bosnia and Herzegovina have molecular methods available, and they are limited to great and reference centres.

Also, the method by which MRSA diagnostics time can be significantly shorter, is method of latex agglutination by which PBP2a is detected (BioMerieux, France). Method does not require special equipment and stuff training, antigen extraction is simple, results relevant [67]. The method's purpose is not for detection MRSA coding *mec*A gene, which is not prominent, because such test is falsely negative.

Detection of virulent CA-MRSA strains is also important for application of measures for spreading prevention during admission to hospital [68] of the patient

#### *Infections and Sepsis Development*

with CA MRSA infection and stay with seriously ill patients to which infection can have a fatal outcome. Some authors suggest selection of patients in intensive care units aiming at improving treatment [69]. During patient treatment with infection CA-MRSA, it is necessary to undertake prevention measures for spreading isolates, and avoid using common objects with other patients. It is considered that relatively great number of epidemic infections CA-MRSA is caused just by transmitting pathogens over objects of common use (soaps, towels…).

Transmission of out-of-hospital MRSA to laboratory employees is registered. Wagenvoort et al. [70] as well as to the doctor who resuscitated child with necrotic pneumonia caused by CA-MRSA [71] strain so it takes utmost care in treating this transmissible, more often described pathogen.

At this moment, MRSA strains as causes of epidemic should be typed in single hospitals or reference laboratories to establish whether they are CA-MRSA or HA-MRSA strains, for larger group of patients and stuff can represent risk that could demand new control strategies for CA-MRSA strains. New strategies can include screening the hospital stuff, enhanced follow up for cases with the infection beginning in hospital and out-of-hospital environment and vice versa. They would, also, include improved prevention and infection control measures in general population, focusing on MRSA in contaminated area [72].

Periodical examination of antimicrobial sensitivity profile of MRSA strains (cause of infection), in combination with representative isolate set typing of specific area, is useful to ensure necessary empirical therapy, having in mind that appearance CA-MRSA in certain parts of the world brought changes in empirical therapy of staphylococci infections.

Reference laboratories should periodically continue representative isolate sets typing to ensure adequate follow up of MRSA trends, as well as appearance of new types.

For complete estimation of their epidemiology, MRSA infections should be characterised as:

