Molecular characterization of Staphylococcus aureus isolates from southwest of Iran using spa and SCCmec typing methods

Epidemiological characterization of clinical isolates of meticillin resistant Staphylococcus aureus through multilocus sequence typing and staphylococcal cassette chromosome mec typing in Northwest Iran

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA), is considered a potential and aggressive nosocomial pathogen. It accounts for 50% of S. aureus isolates in tertiary hospitals in Iran, however, there is no sufficient evolutionary and epidemiological investigation about this medically important bacterium. We aimed to study the lineage and evolution of MRSA in Northwest Iran during 2021-2022 based on the obtained phenotypic and genotypic characteristics.

MATERIALS AND METHODS

Seventy-two non-duplicate MRSA isolates were collected from 3 referral hospitals in Tabriz, Ardebil, and Urmia cities. The antimicrobial susceptibility patterns were determined by disk diffusion test and micro broth dilution methods. Thereafter 4 virulence genes (eta, etb, pvl, tst) and 5 types of staphylococcal cassette chromosome mec (SCCmec) were detected by PCR. In the final step, representative isolates were selected to be studied by Multilocus sequence typing (MLST).

RESULTS

The highest resistance was observed to erythromycin and clindamycin at a rate of 76.4%, followed by ciprofloxacin (61.1%), gentamicin (54.2%), rifampin (38.9%), and co-trimoxazole (27.8%). All isolates were susceptible to vancomycin. The virulence genes of etb, pvl, tst, and eta were detected in 50%, 29.2%, 21.8%, and 13.9% of isolates, respectively. SCCmec types III and I were the most prevalent types, followed by types IV, II, and V. MLST analysis revealed 6 sequence types: ST6854, ST5282, ST127, ST7804, ST1607, and ST7784. Two MLST-based clonal complexes (CC8, and CC97) were identified as well.

CONCLUSION

The ST numbers were non-repetitive. CC8 as a pandemic clone and an individual lineage and clinically significant clade was reported as the most prevalent clonal complex. It is essential periodic evaluations of antibiotic susceptibility patterns and study the evolutionary characteristics of medical-challenging microorganisms in particular MRSA to effectively treat and restrict the outbreaks.

New update on molecular diversity of clinical Staphylococcus aureus isolates in Iran: antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing

BACKGROUND

Staphylococcus aureus is often considered as a potential pathogen and resistant to a wide range of antibiotics. The pathogenicity of this bacterium is due to the presence of multiple virulence factors and the ability to form biofilm. SCCmec types I, II and III are mainly attributed to HA-MRSA, while SCCmec types IV and V have usually been reported in CA-MRSA infections.

METHODS AND RESULTS

In this study, we performed a cross-sectional study to determine the antimicrobial resistance, adhesion and virulence factors, biofilm formation and SCCmec typing of clinical S. aureus isolates in Iran. S. aureus isolates were identified using microbiological standard methods and antibiotic susceptibility tests were performed as described by the Clinical and Laboratory Standards Institute (CLSI) guidelines. Inducible resistance phenotype and biofilm formation were determined using D-test and tissue culture plate methods, respectively. Multiplex-PCRs were performed to detect adhesion and virulence factors, antibiotic resistance genes, biofilm formation and SCCmec typing by specific primers. Among 143 clinical samples, 67.8% were identified as MRSA. All isolates were susceptible to vancomycin. The prevalence of cMLS_B, iMLS_B and MS phenotypes were 61.1%, 22.2% and 14.8%, respectively. The TCP method revealed that 71.3% of isolates were able to form biofilm. The predominant virulence and inducible resistance genes in both MRSA and MSSA isolates were related to sea and ermC respectively. SCCmec type III was the predominant type.

CONCLUSIONS

Data show the high prevalence rates of virulence elements among S. aureus isolates, especially MRSA strains. This result might be attributed to antibiotic pressure, facilitating clonal selection.

Comparative study of Staphylococcus aureus from burn patients and healthcare workers in a burn center, Yazd, Iran

Healthcare workers (HCWs) are proposed as the potential source of transmission of Staphylococcus aureus to hospitalized patients, especially in burn units. This study aimed to investigate S. aureus from burn wound infections and those from the nose of HCWs in terms of antibiotic resistance, the presence of Panton-Valentine leucocidin-encoding gene (pvl) and the arginine catabolic mobile element (ACME), and the ability for biofilm formation. Also, the genetic diversity of isolates was assessed using staphylococcal protein A (spa) typing and staphylococcal cassette chromosome mec (SCCmec) typing. Overall, regarding the studied factors, significant differences were found neither between isolates from patients and HCWs nor between methicillin-resistant and methicillin-susceptible isolates (except for multidrug resistance which was significantly higher in MRSA). The most frequent SCCmec types were type I and III. ACME-arcA was only detected in isolates from patients and similarly the presence of ACME-opp3 was the most prevalent in this group. The presence of common clonal complexes among patient isolates and more importantly between isolates from patients and HCWs is warning. The high prevalence of virulence factors, both in MRSA and MSSA, emphasizes the importance of MSSA in burn centers. Finding no significant difference in the presence of virulence-associated factors between isolates from patients and HCWs demonstrates the need to take HCWs into account as important reservoirs.

Molecular Evaluation of Traditional Chicken Farm-Associated Bioaerosols for Methicillin-Resistant Staphylococcus aureus Shedding

The outbreak of airborne pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) through bioaerosol, and their molecular characterization around domestic poultry farming areas, was not completely understood. This imposes risk of a MRSA-associated health threat for the relevant livestock food production units. To address this issue, the present study investigated the role of bioaerosol in transmitting MRSA strains in poultry house settings by combining molecular typing, phylogenetic classification, antibiotic susceptibility, and virulence gene distribution patterns. The present study highlights that all 18 bioaerosol and stool samples collected were MRSA positive, with a unique set of virulence factors. Out of 57 isolated MRSA isolates, 68.4% and 19.3% consisted of SCCmec I and IV elements, respectively, which are commonly linked with hospital-acquired and livestock-associated MRSA strains. It is worth noting that the exfoliative toxin eta and etb genes were carried by 100% and 70.2% of all isolates, respectively. Only 17.5% of strains showed the presence of enterotoxin entC. These MRSA isolates were resistant to chloramphenicol (C), ciprofloxacin (CIP), clindamycin (DA), erythromycin (E), and tetracycline (T), signifying their multi-drug resistance traits. A cluster of phylogenetic analysis described that 80.7% and 15.8% of total isolates belonged to Staphylococcus aureus protein A (spa) type t002 and t548. Whereas 3.5% were reflected as a new spa type. Additionally, as per the chi-squared test score value, these two spa types (t002 and t548) have a distribution correlation with HA-MRSA and LA-MRSA in all the samples (p < 0.005, chi-squared test; degree of freedom = 1). Ultimately, this study highlights the prevalence of MRSA colonization in the conventional poultry farm environment, showing the risk of bioaerosol transmission, which needs epidemiological attention and prevention strategies.

Genomic Insights into Methicillin-Resistant Staphylococcus aureus spa Type t899 Isolates Belonging to Different Sequence Types

This study showed the genetic diversity and population structure of S. aureus presenting the same spa type, t899, but belonging to different STs. Our findings revealed that these isolates vary deeply in their core and accessory genomes, contrary to what is regularly inferred from studies using spa typing only.

Methicillin-resistant Staphylococcus aureus (MRSA) presenting spa type t899 is commonly associated with sequence type 9 (ST9) but is also increasingly linked to ST398. This study provides genomic insight into the diversity of t899 isolates using core genome multilocus sequence typing (cgMLST), single nucleotide polymorphism (SNP)-based phylogeny, and the description of selected antimicrobial resistance and virulence markers. The SNP-based phylogenic tree showed that isolates sharing the same spa type (t899) but different STs highly diverged in their core and accessory genomes, revealing discriminant antimicrobial resistance (AMR) and virulence markers. Our results highlighted the idea that in a surveillance context where only spa typing is used, an additional multiplex PCR for the detection of the tet(M), sak, and seg genes would be valuable in helping distinguish ST9 from ST398 isolates on a routine basis.

IMPORTANCE This study showed the genetic diversity and population structure of S. aureus presenting the same spa type, t899, but belonging to different STs. Our findings revealed that these isolates vary deeply in their core and accessory genomes, contrary to what is regularly inferred from studies using spa typing only. Given that identical spa types can be associated with different STs and that spa typing only is not appropriate for S. aureus isolates that have undergone major recombination events which include the passage of the spa gene (such as in t899-positive MRSA), the combination of both MLST and spa typing methods is recommended. However, spa typing alone is still largely used in surveillance studies and basic characterization. Our data suggest that additional markers, such as tet(M), sak, and seg genes, could be implemented in an easy and inexpensive manner in order to identify S. aureus lineages with a higher accuracy.

Prevalence and molecular epidemiology of ceftaroline non-susceptible methicillin-resistant Staphylococcus aureus isolates, first clinical report from Iran

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major pathogens in Iran with a high prevalence and a high level of antibiotic resistance. Ceftaroline is a fifth generation cephalosporin binding and inhibiting penicillin binding protein (PBP2a).

METHODS

In the present study, 228 clinical MRSA isolates were collected from four cities of Iran and their susceptibility to ceftaroline was evaluated by E-test and the disk diffusion method.

RESULTS

Our results showed a high susceptibility rate (97.3%) to ceftaroline in MRSA strains from Iran. Six isolates were found to be ceftaroline non-susceptible (CPT-NS) with Minimum inhibitory concentration (MIC) ≥2 µg/mL. All CPT-NS isolates were isolated from blood and tracheal aspirate and belonged to SCCmec type III as well as agr type I and were all susceptible to vancomycin. Out of six isolates, three, two and one belonged to spa type t030, t4864, and t969, respectively. Vancomycin, quinupristin/dalfopristin, linezolid, chloramphenicol, and tigecycline were the most active agents against CPT-NS isolates.

CONCLUSION

Due to the broad-spectrum activity and low toxicity of ceftaroline as well as the increased rate of vancomycin resistance among MRSA strains in recent years, ceftaroline can be considered as a novel approach to treat MRSA-induced infections.

Evaluation of high-resolution melting analysis for spa-typing of methicillin-resistant and -susceptible Staphylococcus aureus isolates

Molecular characterization of Staphylococcus aureus isolates from nosocomial and community-acquired infections using accurate, reproducible, and rapid typing methods is essential for the fast identification of prevalent and epidemic strains. Although sequence-based spa typing is highly effective, PCR-based techniques (such as high-resolution melting curve analysis, HRM) are simpler, less expensive, faster, and can be performed in a single and closed-tube assay format, thereby reducing the risk of contamination. A total of 51 methicillin-resistant S. aureus (MRSA) (n = 26) and methicillin-sensitive S. aureus (MSSA) (n = 25) isolates from Karaj (n = 10) and Yasuj (n = 41), Iran, were subjected to HRM. All selected isolates were identified by the standard spa-typing method. Among the 51 tested isolates, 11 genotype profiles were distinguished from 12 spa types. Strains t1077 and t1816 exhibited the highest and lowest melting temperatures (81.8°C and 79.4°C), with 46.7% and 39.8% G + C contents, respectively. Strains t706 and t1816, with almost identical G + C contents, had the same HRM genotypes, but their curves differed due to different G + C distributions. Four standard spa types (strains t030, t037, t701 and t5598) were differentiated correctly and their melting temperatures were 81.2°C, 81.4°C, 80.4°C and 80.1°C, respectively. We demonstrated that HRM profiling is a rapid method which enables the accurate screening of certain strains (especially the endemic ones), and may be used for bacterial surveillance. However, it cannot replace sequence-based spa typing, especially for newly emerging spa types, and therefore cannot be used as a standardized global method.

The global prevalence of Daptomycin, Tigecycline, Quinupristin/Dalfopristin, and Linezolid-resistant Staphylococcus aureus and coagulase-negative staphylococci strains: a systematic review and meta-analysis

Objective

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCoNS) are among the main causes of nosocomial infections, which have caused major problems in recent years due to continuously increasing spread of various antibiotic resistance features. Apparently, vancomycin is still an effective antibiotic for treatment of infections caused by these bacteria but in recent years, additional resistance phenotypes have led to the accelerated introduction of newer agents such as linezolid, tigecycline, daptomycin, and quinupristin/dalfopristin (Q/D). Due to limited data availability on the global rate of resistance to these antibiotics, in the present study, the resistance rates of S. aureus, Methicillin-resistant S. aureus (MRSA), and CoNS to these antibiotics were collected.

Method

Several databases including web of science, EMBASE, and Medline (via PubMed), were searched (September 2018) to identify those studies that address MRSA, and CONS resistance to linezolid, tigecycline, daptomycin, and Q/D around the world.

Result

Most studies that reported resistant staphylococci were from the United States, Canada, and the European continent, while African and Asian countries reported the least resistance to these antibiotics. Our results showed that linezolid had the best inhibitory effect on S. aureus. Although resistances to this antibiotic have been reported from different countries, however, due to the high volume of the samples and the low number of resistance, in terms of statistical analyzes, the resistance to this antibiotic is zero. Moreover, linezolid, daptomycin and tigecycline effectively (99.9%) inhibit MRSA. Studies have shown that CoNS with 0.3% show the lowest resistance to linezolid and daptomycin, while analyzes introduced tigecycline with 1.6% resistance as the least effective antibiotic for these bacteria. Finally, MRSA and CoNS had a greater resistance to Q/D with 0.7 and 0.6%, respectively and due to its significant side effects and drug-drug interactions; it appears that its use is subject to limitations.

Conclusion

The present study shows that resistance to new agents is low in staphylococci and these antibiotics can still be used for treatment of staphylococcal infections in the world.

Determining spa-type of methicillin-resistant Staphylococcus aureus (MRSA) via high-resolution melting (HRM) analysis, Shiraz, Iran

OBJECTIVES

Molecular typing methods are useful for rapid detection and control of a disease. Recently, the use of high-resolution melting (HRM) for spa typing of MRSA isolates were reported. This technique is rapid, inexpensive and simple for genotyping and mutation screening in DNA sequence. The aim of this study was to evaluate the ability of HRM-PCR to analysis spa genes amongst MRSA isolates.

RESULTS

A total of 50 MRSA isolates were collected from two teaching hospitals in Shiraz, Iran. The isolates were confirmed as MRSA by susceptibility to cefoxitin and detection of mecA gene using PCR. We used HRM analysis and PCR-sequencing method for spa typing of MRSA isolates. In total, 15 different spa types were discriminate by HRM and sequencing method. The melting temperature of the 15 spa types, using HRM genotyping were between 82.16 and 85.66 °C. The rate of GC % content was 39.4-46.3. According to the results, spa typing of 50 clinical isolates via PCR-sequencing and HRM methods were 100% similar. Consequently, HRM method can easily identify and rapidly differentiate alleles of spa genes. This method is faster, less laborious and more suitable for high sample at lower cost and risk of contamination.

Characterization of SCCmec, spa types and Multi Drug Resistant of methicillin-resistant Staphylococcus aureus isolates among inpatients and outpatients in a referral hospital in Shiraz, Iran

Objectives

Molecular typing such as spa typing is used to control and prevent Staphylococcus aureus widespread in hospitals and communities. Hence, the aim of this study was to find the most common types of S. aureus strain circulating in Shiraz via spa and SCCmec typing methods.

Results

Total of 159 S. aureus isolates were collected from two tertiary hospitals in Shiraz. Isolates were identified by biochemical tests. Antimicrobial susceptibility tests were performed by standard disk diffusion method and then genetic analysis of bacteria was performed using SCCmec and spa typing. In this study 31.4% of the isolates were methicillin-resistant S. aureus. The majority of isolates were SSCmec type III. Spa type t030 was the most prominent type among MRSA strains. For the first time in Iran, spa003, t386, t1877, t314, t186, t1816, t304, t325, t345 were reported in this study. It was shown that there is a possibility that these spa types are native to this region. Our findings showed that SCCmec II, III and IV disseminate from hospital to community and vice versa. Thus, effective monitoring of MRSA in hospital and community is necessary.

Genotype Distribution of Panton-Valentine Leukocidin (PVL)-Positive Staphylococcus aureus Strains Isolated from Wound-Related Infections: a Three-Year Multi-Center Study in Tehran, Iran

The spread of Panton-Valentine leucocidin (PVL)-carrying S. aureus strains in patients with wound infections in both the community and hospitals is increasing in some areas of Iran. In the present study, we determined the molecular characteristics and distribution of PVL-producing S. aureus strains isolated from wound infections. Genes encoding resistance, toxins, and staphylococcal enterotoxins were analyzed by polymerase chain reaction assays. Genotyping was performed using multi-locus sequence typing. Aminoglycoside resistance genes including ant (4')-Ia (57.4%) and aac (6')-Ie/aph (2″) (45.7%) were the most prevalent genes in isolates. Staphylococcal enterotoxin type A, as the most frequent type, was present in 20.2% of isolates. Strains belonged to seven clonal complexes. The most frequent clonal complex was CC30 (ST30) (29.8%), followed by CC22 (ST22) (21.3%), CC8 (ST8 and ST931) (17%), CC88 (ST88) (10.6%), CC59 (ST59 and ST338) (8.5%), CC1 (ST772 and ST1) (7.5%), and CC15 (ST15) (5.3%). Our findings indicated an increasing trend of CC30, carrying a wide range of resistance and toxin genes, which could present an obstacle in the treatment of patients with wound infections. Further studies are required to investigate the carriage of resistance, the antibiotic susceptibility pattern, and toxins encoding genes in different molecular types.

Genotyping and antimicrobial resistance of Staphylococcus aureus isolates from dairy ruminants: differences in the distribution of clonal types between cattle and small ruminants

Staphylococcus aureus is part of the normal flora of animals, and represents one of the leading causes of contagious mastitis in dairy herds worldwide. Sixty-seven epidemiologically unrelated S. aureus isolates from nasal and mastitis milk samples of dairy-producing animals (32 cows, 25 sheep, and 10 goats) were characterized by antimicrobial susceptibility testing and spa typing followed by multilocus sequence typing (MLST) on representative isolates and SCCmec-typing on methicillin-resistant S. aureus (MRSA) isolates. The highest resistance was observed to penicillin (64.2%, 43/67), followed by tetracycline (23.9%, 16/67), erythromycin (22.4%, 15/67), and streptomycin (17.9%, 12/67). In general, 18 spa types (including newly identified t16958) and 13 sequence types (STs) belonging to 8 clonal complexes (CCs) were detected. The cow-associated isolates were mainly assigned to CC5 (n = 18, related to t267-ST97, t521-ST352, t527-ST97, t304-ST6, and t084-ST15), followed by CC398 (n = 6, t937-ST291), CC45 (n = 3, t230-ST45), CC88 (n = 2, t2526-ST88), CC22 (n = 2, t3680-ST22), and CC522 (n = 1, t3576-ST522). Small ruminant isolates were mostly clustered into CC522 (n = 29, related to t3576, t1534, t16958, t7308, t7311, t7305 [ST522], t1534-ST2057, and t5428-ST2079). Two isolates from cows with mastitis were found to be MRSA, exhibited a composite profile of t937-ST291-SCCmecIV. No isolates carried the PVL and mecC genes. A significant difference in clonal types of S. aureus isolates from cows in comparison with those from small ruminants was found. This study demonstrated the circulation of diverse clones of S. aureus among dairy animals in Iran, with a different clonal composition between cows and small ruminants. The current study also reports MRSA-related mastitis in dairy cows, emphasizing the need for comprehensive surveillance.

Genotypic characterization of Staphylococcus aureus isolated from a burn centre by using agr, spa and SCCmec typing methods

Infections caused by Staphylococcus aureus remain a major global healthcare problem. We aimed to find the common lineages of S. aureus strains circulating in a burn hospital in Tehran. A total of 167 isolates of S. aureus obtained from patients, healthcare workers (HCWs) and environment in Shahid Motahari burn hospital were genotyped by using spa, agr and staphylococcal cassette chromosome mec (SCCmec) typing methods. Antimicrobial susceptibility testing was performed by using the disc diffusion method. The frequency of methicillin-resistant S. aureus (MRSA) was 64.7% (n = 108), with distribution frequencies among patient, HCW and surface isolates of 64.2% (n = 79), 50% (n = 7) and 73.3% (n = 22), respectively. SCCmec type III (75%, n = 81) was found to be the most frequent SCCmec type among MRSA isolates, followed by SCCmec type I (20.4%, n = 22) and SCCmec type IV (1.8%, n = 2). The remaining MRSA isolates (2.8%, n = 3) were nontypeable by this method. About 78.4% (n = 131), 10.2% (n = 17) and 4.8% (n = 8) of all isolates were characterized as agr types I, II and III, respectively, and the other isolates (6.6%) were nontypeable. spa types t030 and t037 constituted the first and second most predominant spa types found in 56.4% (n = 57) and 25.6% (n = 26) of isolates, respectively. We also report here a novel spa type, t16471. The most prevalent genotypes of the isolates found among patient, surface and HCW samples were SCCmec type III/t030, t037/agr type I. Continuous tracking of epidemic isolates and better hospital infection control policies are recommended to efficiently prevent the spread of bacteria to inpatients.

Staphylococcal cassette chromosome mec (SCCmec) and characterization of the attachment site (attB) of methicillin resistant Staphylococcus aureus (MRSA) and methicillin susceptible Staphylococcus aureus (MSSA) isolates

This study was designed to screen for SCCmec types and to characterize the attachment site (attB) and universal insertion site (orfX) of SCCmec in a collection of 27 isolates (n = 11) methicillin resistant S. aureus and (n = 16) methicillin susceptible S. aureus isolates in Malaysia. Screening of SCCmec types and characterization of the attachment site was carried out using PCR amplification and Sanger's sequencing method. The result showed that a large proportion of the MRSA isolates carried SCCmec type III 7/11 (63%). Three isolates 3/11 (27%) and 1/11 (9.0%) carried SCCmec type II and IVd respectively. Amplification of the universal insertion site of the SCCmec (orfX) and attachment site (attB) showed that all 16 S. aureus isolates were positive for the orfX gene, while only 7 were positive for the attB gene. Phylogenetic diversity showed that the isolates clustered around strains with features similar to a community acquired MRSA. In conclusion, a high carriage rate of SCCmec type III was observed. The result also showed that all the S. aureus isolates have the orfX structure; however, not all isolates possesses the attB site on the 3' end of the orfX region.

Molecular Characterization of Methicillin-Resistant Staphylococcus aureus Isolates, Isolated from a Burn Hospital in Southwest Iran in 2006 and 2014

OBJECTIVES

Incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing every year, especially in burn patients with a high rate of morbidity and mortality. Molecular and epidemiologic studies are useful practices for understanding the relatedness of isolates in a single patient or a hospital. This study aimed at determining molecular characterizations of isolates collected in 2006 and 2014 using S. aureus-specific staphylococcal protein A (Spa) typing and Multilocus Sequence Typing (MLST) methods.

MATERIALS AND METHODS

Totally, 71 MRSA isolates were collected during the last two studies (2006 and 2014) from burn patients at Taleghani Burn Centre. After confirmation, all isolates were analysed using MLST and Spa typing methods.

RESULTS

We reported the emergence of Spa type t021, ST-30-IV MRSA isolates, which were PVL-positive in 14.6% of the cases and t12366, ST-8-IV isolates, which were PVL-negative in 9.8% of the cases. In 2014 study, Spa typing of MRSA isolates revealed five different spa types. Overall, in two studies, t037, ST-239, SCCmec III, and CC8 were predominant clones and they were reported in 63% of the cases.

CONCLUSION

The predominance of ST-239 in this region during the last eight years is a major concern. It also has a disturbing impact on the management of staphylococcal infections. Moreover, the SCCmec type IV strain is able to disseminate rapidly in hospital environments, demanding an improvement in infection-control policy.

Distribution of the Most Prevalent Spa Types among Clinical Isolates of Methicillin-Resistant and -Susceptible Staphylococcus aureus around the World: A Review

Background:Staphylococcus aureus, a leading cause of community-acquired and nosocomial infections, remains a major health problem worldwide. Molecular typing methods, such as spa typing, are vital for the control and, when typing can be made more timely, prevention of S. aureus spread around healthcare settings. The current study aims to review the literature to report the most common clinical spa types around the world, which is important for epidemiological surveys and nosocomial infection control policies.

Methods: A search via PubMed, Google Scholar, Web of Science, Embase, the Cochrane library, and Scopus was conducted for original articles reporting the most prevalent spa types among S. aureus isolates. The search terms were “Staphylococcus aureus, spa typing.”

Results: The most prevalent spa types were t032, t008 and t002 in Europe; t037 and t002 in Asia; t008, t002, and t242 in America; t037, t084, and t064 in Africa; and t020 in Australia. In Europe, all the isolates related to spa type t032 were MRSA. In addition, spa type t037 in Africa and t037and t437 in Australia also consisted exclusively of MRSA isolates. Given the fact that more than 95% of the papers we studied originated in the past decade there was no option to study the dynamics of regional clone emergence.

Conclusion: This review documents the presence of the most prevalent spa types in countries, continents and worldwide and shows big local differences in clonal distribution.