Hospital clones of Panton-Valentine leukocidin-positive and methicillin-resistant Staphylococcus aureus circulating in the Tehran community

Methicillin-resistant Staphylococcus aureus colonization of infectious and non-infectious skin and soft tissue lesions in patients in Tehran

Background

The most common clinical manifestations of Staphylococcus aureus strains in the community are skin and soft-tissue infections. S. aureus could colonize the body sites and complicate the pathogenesis of skin diseases. S. aureus colonization is a risk factor for severe conditions such as bone and joint infections, pneumonia, bacteremia, and endocarditis. This study aimed to investigate the prevalence of S. aureus strains in skin and soft tissue infections and other skin disorders in patients referring to dermatology clinics and to evaluate the antibiotic resistance pattern and molecular characteristics of S. aureus isolates.

Methods

Skin swabs were collected from the lesional sites in 234 outpatients referring to dermatology clinics in three hospitals in Tehran. Antibiotic susceptibility, biofilm formation, and hemolysis tests were performed for isolates. PCR was done for SCCmec typing, agr grouping, and virulence genes detecting.

Results

The prevalence of S. aureus strains among patients with skin and soft-tissue infections and other skin lesions was 44.77% (30/67) and 44.91% (75/167), respectively. Also, 59 (56.19%) isolates were MRSA, 35.57% were HA-MRSA, and 30.5% were CA-MRSA. The psmα gene was more prevalent (62.8%) among isolates, followed by hlaα (56.1%), tsst-1 (15.2%) eta (13.3%), etb (6.6%), and pvl (2.8%). The agr specificity groups I, II, III, and IV were identified in 49.5, 21.9, 11.4, and 14.2% of S. aureus isolates, respectively. Most (56%) S. aureus isolates produced a moderate biofilm, and 23.8% of them produced strong biofilms. α-hemolysin (46.6%), β-hemolysin (25.7%), γ-hemolysin (19%), and both α and β-hemolysin (5.7%) were also produced by isolates.

Conclusion

The present study results indicated high colonization of skin lesions by HA-MRSA and CA-MRSA clones; MRSA strains were more resistant to antibiotics, contained various toxin genes, and were able to form biofilms. Therefore, they could play a vital role in the pathogenesis of various skin diseases; also, they could spread and cause infections in other body sites. Eradication and decolonization strategies could prevent recurrent infections and the spread of resistant strains and improve skin conditions.

Genetic diversity of healthcare-associated methicillin-resistant Staphylococcus aureus isolates from Southern Iran

Staphylococcus aureus is a common pathogen causing hospital infections. The increasing rate of healthcare-associated infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in developing countries has led to many public health problems. This study aimed to investigate the molecular epidemiology as well as the antibiotic resistance pattern of clinical isolates of MRSA from Southern Iran. A total of 135 S. aureus isolates were collected from the patients referred to three hospitals in South Iran. The phenotypic and genotypic diagnosis of MRSA isolates was performed by disk diffusion and PCR methods, respectively. The antibiotic resistance pattern for MRSA isolates was performed using Kirby-Bauer method. The molecular epidemiology of isolates was performed by MLST, Spa typing and SCCmec typing. From 135 S. aureus isolates, 50 (37%) MRSA strains were detected from which two different sequence types including ST239 and ST605 were identified. SCCmec type III was the most common profile (50%) and t030 was the predominant spa type (48%) among the strains. The MRSA isolates had the highest resistance to penicillin (100%), tetracycline (88%), levofloxacin (86%), ciprofloxacin (84%), erythromycin (82%), gentamicin (80%), and clindamycin (78%). The results of this study show that the most common genetic type among the MRSA isolates was ST239-SCCmec III/t030. The rapid and timely detection of MRSA and the administration of appropriate antibiotics according to the published antibiotic resistance patterns are essential. Furthermore, the continuous and nationwide MRSA surveillance studies are necessary to investigate clonal distribution and spreading of MRSA from community to hospitals.

Clonal diversity and genomic characterization of Panton-valentine Leukocidin (PVL)-positive Staphylococcus aureus in Tehran, Iran

Background

Some Staphylococcus aureus strains produce Panton-Valentine leukocidin (PVL), a bi-component pore-forming toxin, which causes leukocyte lysis and tissue necrosis. Currently, there is very limited information on the molecular epidemiology of PVL-encoding S. aureus strains in Iran. This study aimed to determine the molecular epidemiology and genetic background of PVL-positive S. aureus clinical strains isolated from Iranian patients.

Methods

A total of 28 PVL-positive S. aureus strains were detected from 600 S. aureus isolates between February 2015 and March 2018 from different hospitals in Tehran, Iran. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Molecular genotyping was performed using SCCmec and accessory gene regulator (agr) typing, PVL haplotyping, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE).

Results

The highest antibiotic resistance rate was found to be against erythromycin (57.1%), followed by ciprofloxacin (42.8%) and clindamycin (35.7%). Moreover, 19 (67.9%) out of 28 S. aureus isolates were identified as MRSA, including CA-MRSA (14/19, 73.7%) and HA-MRSA (5/19, 26.3%). SCCmec type IVa was detected as the predominant type (10/19, 52.6%), followed by type III (5/19, 26.3%) and type V (4/19, 21.1%). The agr type I was identified as the most common type (14/28, 50%), and H and R haplotype groups were observed at frequencies of 67.9 and 32.1%, respectively. Among H variants, the predominant variant was H2 (78/9%). The isolates encompassed 21 different sequence types (STs), including 16 new STs (ST5147 to ST5162). Based on eBURST analysis, the isolates were clustered into five CCs, including CC30, CC22, CC1, CC8, and CC5 (ST5160), and nine singletons. PFGE typing showed that 24 isolates were clustered into A (4 pulsotypes), B (9 pulsotypes), and C (11 pulsotypes) clusters.

Conclusions

A high prevalence of PVL-positive CA-MRSA strains was detected in Iran. The majority of PVL-positive isolates were of H (mostly H2) variant, while R variant was harbored by 100% of PVL-positive MRSA strains. Also, CC8, CC22, and CC30 were identified as the dominant clones among PVL-encoding S. aureus strains. This study promotes a better understanding of the molecular epidemiology and evolution of PVL-positive S. aureus strains in Iran.

Reduced Susceptibility to Chlorhexidine among Staphylococcus aureus Isolates in Israel: Phenotypic and Genotypic Tolerance

Antiseptic use for body decolonization is the main activity applied to prevent healthcare-associated infections, including those caused by S. aureus. Consequentially, tolerance to several antiseptics such as chlorhexidine gluconate (CHG) has developed. This study aimed to estimate the prevalence of CHG tolerance among S. aureus strains in Israel and to evaluate factors that may affect this tolerance. Furthermore, it tested the associations between phenotypic and genotypic CHG tolerance. S. aureus strains (n = 190) were isolated from clinical samples of patients admitted to various medical institutions in Israel. Phenotypic susceptibility to CHG was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Genotypic tolerance was detected using real-time PCR for detection of qac A/B genes. MIC for the antibiotic mupirocin was determined using the Etest method. Presence of the Panton-Valentine Leucocidin (pvl) toxin, mecA and mecC genes was detected using an eazyplex^® MRSAplus kit (AmplexDiagnostics GmbH, Gars, Germany). CHG tolerance was observed in 13.15% of the isolates. An association between phenotypic and genotypic tolerance to CHG was observed. Phenotypic tolerance to CHG was associated with methicillin resistance but not with mupirocin resistance. Additionally, most of the CHG-tolerant strains were isolated from blood cultures. In conclusion, this work shed light on the prevalence of reduced susceptibility to CHG among S. aureus strains in Israel and on the characteristics of tolerant strains. CHG-tolerant strains were more common than methicillin-resistant ones in samples from invasive infections. Further research should be performed to evaluate risk factors for the development of CHG tolerance.

Constellation of methicillin-resistant genomic islands (SCCmec) among nasal meticillin-resistant Staphylococcus aureus isolates

The apprehensiveness for the knowledge vacuum on existential threat of nasal carriage of pvl+ healthcare-acquired meticillin-resistant Staphylococcus aureus (HA-MRSA) strains amongst subjects in hospitals have led us to pursue a grasp on the constellation of staphylococcal cassette chromosome mec (SCCmec) types and pvl gene among mecA positive MRSA nasal strains. This was accomplished by phenotypic (catalase, coagulase, Microgen staph ID, ORSAB) and genotypic (polymerase chain reaction) biotyping techniques. All the mecA+ strains harboured the SCCmec gene; SCCmec type I prevailed in 43.75% and pvl was found in 42.1% of the isolates. Dual carriage of mecA and pvl genes occurred in six (37.5%, n = 6/16) strains. Overall, majority of the mecA+ MRSA strains documented in this study carried SCCmec elements of the HA genotype with a hint of community-acquired (CA)genotype suggesting a possible coexistence of both HA-MRSA and community-acquiredhealthcare-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) strains. Consequently, the implementation of methodical surveillance is needed for the evaluation of potential shifts in directionality of (HA-MRSA/CA-MRSA) pvl+ MRSA clones in our hospitals for effective and prudent antimicrobial stewardship.