Invasive pectoral abscess and costal osteomyelitis with bloodstream infection caused by methicillin-resistant Staphylococcus aureus after nasal septoplasty in an immunocompetent adult patient.

There are few reports of multilocus sequence type (ST) 5/staphylococcal cassette chromosome (SCC) mec type IVc/toxic shock syndrome toxin (TSST)-1- positive methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections. We report a case of community-onset MRSA (CO-MRSA) bloodstream infection in a healthy 41-year-old Japanese man after nasal septoplasty, followed by pectoral abscess and costal osteomyelitis. The patient presented with right anterior chest pain and fever. After admission, MRSA was isolated from two sets of blood cultures, and vancomycin was administered. On the fifth day, contrast-enhanced computed tomography (CT) scan and contrast-enhanced magnetic resonance imaging (MRI) scan showed an abscess in the right anterior chest to the right subpleural region. The dosage of vancomycin (4 g/day) did not reach the effective blood concentration; therefore, there was a switch to daptomycin. On the 23rd day, contrast-enhanced MRI revealed osteomyelitis of the right first rib, and as a result, linezolid was initiated. Two weeks later, contrast-enhanced CT of the chest showed improvement in the abscess. The patient was treated for 6 weeks during hospitalization and then switched to minocycline for 10 weeks. Molecular characterization of this isolate showed that it was ST5/SCCmec type IVc/TSST-1-positive/Panton-Valentine leucocidin (PVL)-negative. PVL-negative CO-MRSA can lead to hematogenous osteomyelitis and abscess even if the patient is immunocompetent, and if isolated from blood cultures, it is important to repeat imaging studies, even if the initial imaging studies were normal. It is possible that this strain contributes to the pathogenesis of invasive CO-MRSA, but further case accumulation is needed.

High prevalence of t895 and t9364 spa types of methicillin-resistant Staphylococcus aureus in a tertiary-care hospital in Mexico: different lineages of clonal complex 5.

BACKGROUND: Staphylococcus aureus is a leading cause of broad-spectrum infections both in the community and within healthcare settings. Methicillin-resistant Staphylococcus aureus (MRSA) has become a global public health issue. The aim of this study was to examine the clinical and molecular characteristics of Staphylococcus aureus isolates and to define the population structure and distribution of major MRSA clones isolated in a tertiary-care hospital in Mexico. RESULTS: From April 2017 to April 2018, 191 Staphylococcus aureus isolates were collected. The frequency of MRSA was 26.7%; these strains exhibited resistance to clindamycin (84.3%), erythromycin (86.2%), levofloxacin (80.3%), and ciprofloxacin (86.3%). The majority of MRSA strains harbored the SCCmec type II (76.4%) and t895 (56.8%) and t9364 (11.7%) were the most common spa types in both hospital-associated MRSA and community-associated MRSA isolates. ST5-MRSA-II-t895 (New York /Japan clone) and ST1011-MRSA-II-t9364 (New York /Japan-Mexican Variant clone) were the most frequently identified clones. Furthermore, different lineages of Clonal Complexes 5 (85.4%) and 8 (8.3%) were predominantly identified in this study. CONCLUSION: Our study provides valuable information about the epidemiology of MRSA in a city of the central region of Mexico, and this is the first report on the association between t895 and t9364 spa types and ST5 and ST1011 lineages, respectively. These findings support the importance of permanent surveillance of MRSA aimed to detect the evolutionary changes of the endemic clones and the emergence of new strains.

Antimicrobial resistance and virulence genes profiling of methicillin-resistant Staphylococcus aureus isolates in a burn center: A 5-year study.

Methicillin-resistant S. aureus (MRSA) has attracted more and more attention in recent years, especially in burn medical centers. Here we conducted a 5-year period study to evaluate the MRSA infection in our burn center. The staphylococcal chromosomal cassette mec (SCCmec) typing, antimicrobials susceptibility and virulence profiles were also performed among the MRSA isolates. Of the 259 S. aureus isolates, 239 (92.28%) isolates were identified as MRSA. A decreased trend of MRSA isolation rate over time was found (P = 0.0063). Majority of MRSA isolates in our center belonged to SCCmec type III (230/239, 96.23%). Antimicrobials susceptibility tests of the MRSA isolates revealed significantly decreased resistance to clindamycin (P = 0.0183), and increased resistance to chloramphenicol (P = 0.0020) and minocycline (P < 0.0001) over time. Trimethoprim/sulfamethoxazole, clindamycin, vancomycin, teicoplanin and linezolid were suggested to be good choice for MRSA infection in our center. Virulence factors profiling showed that most of MRSA isolates in our center carried the virulence factor pattern of cna-clfA-clfB-eno-fib-icaA-icaD-sea-psmα-lukED-hlg-hlgv-hla-hld (214/239, 89.54%). In conclusion, our study suggests that MRSA infection is serious in our burn center, but presented decreased trend over time. Most of MRSA isolates in our center presented the same virulence factor profile. More attention should be attached to nosocomial infection in burn medical center. Antimicrobials susceptibility changing over time was observed. Antimicrobials susceptibility monitoring is necessary and helps to select appropriate drugs against MRSA infections.

Genetic diversity of methicillin resistant Staphylococcus aureus strains isolated from burn patients in Iran: ST239-SCCmec III/t037 emerges as the major clone.

Methicillin-resistant Staphylococcus aureus (MRSA) as a major cause of infection in health care, hospital and community settings is a global health concern. The purpose of this study was to determine the antibiotic susceptibility pattern and distribution of circulating molecular types of MRSA in a burn hospital in Tehran, the capital of Iran. During a 10-month study period, 106 Staphylococcus aureus isolates were assessed. Isolates were subjected to susceptibility testing using the disk diffusion method and Polymerase Chain Reaction (PCR) for detection of mecA, fem and nuc genes. The presence of PVL and tst encoding genes were determined by PCR method. All the MRSA isolates were genotyped by multilocus sequence typing (MLST), spa typing, SCCmec typing and agr typing. The presence of mecA gene was confirmed in all the Staphylococcus aureus isolates. Antimicrobial susceptibility testing revealed a high resistance rate (90.6%) to ampicillin, tetracycline, and erythromycin. The rates of resistance to remaining antibiotics tested varied between 18.9% and 84.9%. The high- level of resistance to mupirocin was confirmed in 19.8% of MRSA strains isolated from burn patients. Multi-drug resistance was observed in 90.6% of isolates. Sixteen of the 106 MRSA isolates (15.1%) harbored PVL-encoding genes. The majority of our MRSA strains carried SCCmec III (71.7%). ST239-SCCmec III/t037 (34%) was the most common genotype followed by ST239-SCCmec III/t030 (24.5%), ST15-SCCmec IV/t084 (15.1%), ST22-SCCmec IV/t790 (13.2%), and ST239-SCCmec III/t631 (13.2%). Mupirocin resistant MRSA isolates belonged to ST15-SCCmec IV/t084 (40%), ST22-SCCmec IV/t790 (23.3%), ST239-SCCmec III/t631 (20%), and ST239-SCCmec III/t030 (16.7%) clones. The results showed that genetically diverse strains of MRSA are circulating in our burn hospitals with relatively high prevalence of ST239-SCCmec III/t037 clone. The findings support the need for regular surveillance of MRSA to determine the distribution of existing MRSA clones and to detect the emergence of new MRSA clones.

Clinical and pathogenic features of SCCmec type II and IV methicillin-resistant Staphylococcus aureus in Japan.

Staphylococcal chromosomal cassette mec (SCCmec) type IV methicillin-resistant Staphylococcus aureus (MRSA) has rapidly disseminated in healthcare settings, and its characteristics in the United States and Europe are well known. Because Japanese SCCmec type IV MRSA clones are different and less well documented, this retrospective, single center study was done to determine and compare the characteristics of SCCmec type II and IV MRSA in Japan. For the analysis, 55 SCCmec type II and 101 type IV MRSA samples were collected from lower respiratory tract specimens or from skin or soft tissue. The patients of the SCCmec type IV group were significantly younger than those of the type II group (P < 0.001). The rate of MRSA pneumonia was significantly lower for SCCmec type IV than for type II (7.8% vs 29.0%, P = 0.026). In contrast, the rate of skin and soft tissue infection was not significantly different (66.0% vs 61.9%, P = 0.788). The distribution of MRSA pathogenic genes (sea, seb, sem, seo) was significantly different between SCCmec types II and IV (P < 0.001), which indicates that their clonal complex may be completely different. Interestingly, all SCCmec type II MRSA that caused MRSA pneumonia had seb and egc and lacked tst that belonged to sequence type (ST) 764. This is the first study to reveal and compare the characteristics of Japanese SCCmec type II and type IV MRSA. The information from this study will be helpful for the management of Japanese MRSA infection.

Spreading of genes encoding enterotoxins, haemolysins, adhesin and biofilm among methicillin resistant Staphylococcus aureus strains with staphylococcal cassette chromosome mec type IIIA isolated from burn patients.

The emergence of antibiotic-resistant Staphylococcus aureus in particular methicillin-resistant S. aureus (MRSA) is an important concern in burn medical centers either in Iran or worldwide. A total of 128 S. aureus isolates were collected from wound infection of burn patients during June 2013 to June 2014. Multiplex-polymerase chain reaction (MPCR) assay was performed for the characterization of the staphylococcal cassette chromosome mec (SCCmec). Genes encoding virulence factors and biofilm were targeted by PCR. Of 128 S. aureus isolates, 77 (60.1%) isolates were MRSA. Fifty four (70.1%) isolates were identified as SCCmec type IIIA. The most frequently detected toxin genes among MRSA isolates with SCCmec type IIIA were sea (64.1%) and hla (51.8%). The rate of coexistence of sea with hla and sea with hla and hlb was 37% and12.9%, respectively. The sec, eta, tst, pvl, hla and hlb genes were not detected in any of the MRSA isolates. The most prevalent genes encoding biofilm was eno, found in 61.1% of isolates, followed by fib and icaA found in 48.1% and 38.8% of the isolates, respectively. The rate of coexistence of fib + eno + icaA + icaD and fib + eno was 20.3% and 9.2%, respectively. The ebps gene was not detected in any of the isolates. In conclusion, our study indicated that the sea, hla, fib and icaA were most frequent genes encoding virulence factors among MRSA with SCCmec type IIIA isolated from burn wound infection. Moreover, the results of this study shows that the rate of coexistence of genes encoding different virulence factor were high.

Antimicrobial susceptibility and molecular characteristics of methicillin-resistant Staphylococcus aureus in a Japanese secondary care facility.

Methicillin-resistant Staphylococcus aureus (MRSA) is prevalent in Japan, and the Staphylococcus cassette chromosome mec (SCCmec) type II is common among hospital-acquired MRSA isolates. Information pertaining to MRSA characteristics is limited, including SCCmec types, in primary or secondary care facilities. A total of 128 MRSA isolates (90 skin and soft tissue isolates and 38 blood isolates) were collected at a secondary care facility, Kawatana Medical Center, from 2005 to 2011. Antimicrobial susceptibility testing for anti-MRSA antibiotics and molecular testing for SCCmec and virulence genes (tst, sec, etb, lukS/F-PV) were performed. Strains positive for lukS/F-PV were analyzed by multilocus sequence typing and phage open-reading frame typing. SCCmec typing in skin and soft tissue isolates revealed that 65.6% had type IV, 22.2% had type II, 8.9% had type I, and 3.3% had type III. In blood isolates, 50.0% had type IV, 47.4% had type II, and 2.6% had type III. Minimum inhibitory concentrations, MIC(50)/MIC(90), against vancomycin, teicoplanin, linezolid, and arbekacin increased slightly in SCCmec II isolates from skin and soft tissue. MICs against daptomycin were similar between sites of isolation. SCCmec type II isolates possess tst and sec genes at a greater frequently than SCCmec type IV isolates. Four lukS/F-PV-positive isolates were divided into two clonal patterns and USA300 was not included. In conclusion, SCCmec type IV was dominant in blood, skin, and soft tissue isolates in a secondary care facility in Japan. Because antimicrobial susceptibility varies with the SCCmec type, SCCmec typing of clinical isolates should be monitored in primary or secondary care facilities.

Characterization of Staphylococcal Cassette Chromosome mec (SCCmec) in Methicillin-Resistant Staphylococcus epidermidis Strains Isolated from Biomaterial-Associated Infections and their Antibiotic Resistance Patterns.

This work aims to provide an insight into staphylococcal cassette chromosome mec elements and antibiotic resistance in clinical isolates of Staphylococcus epidermidis. The dominating type was SCCmec - IV. Fifteen isolates were assigned to SCCmec type III, two isolates to SCCmec type II. Most isolates were resistant to at least three of the non-ß-lactam antibiotics tested. None of the strains exhibited resistance to new generation antibiotics, such as daptomycin and linezolid. Also, none of these strains showed resistance to tigecycline and only four strains were resistant to rifampin i.e. antibiotics which are very efficient in treating biofilm-associated infections.

The clinical characteristics and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) among very elderly people in Japan.

AIM: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial infection-causing pathogen. The clonal shift from staphylococcal cassette chromosome mec (SCCmec) type II MRSA to SCCmec type IV MRSA has occurred rapidly in acute-care hospitals. However, the epidemiology and clinical impacts of MRSA in geriatric hospitals are poorly documented. We performed a molecular epidemiological analysis of the clinical isolates and retrospectively investigated the clinical characteristics of SCCmec type IV MRSA in elderly individuals. METHODS: MRSA isolates were grouped according to the SCCmec type and virulence genes (tst, sea, seb, sec, and lukS/F-PV), and multi-locus sequence typing (MLST) was performed. RESULTS: Of the 145 MRSA isolates obtained from patients with a median age of 85 years, 100 (69.0%) were obtained from sputum samples, 22 (15.2%) from skin and soft tissues, and seven (4.8%) from blood samples. The most prevalent clone was SCCmec type IV/clonal complex (CC)1/sea+ (59.3%), followed by SCCmec type I/sequence type (ST) 8 (17.3%). Of the 17 (11.7%) strains to which an anti-MRSA drug was administered by a physician, only three were SCCmec type IV/CC1/sea+ (17.6%) and five were SCCmec type I/ST8 (29.4%). SCCmec type IV/CC1/sea+ MRSA was more frequently isolated in long-term care wards than were SCCmec type I/ST8 strains (odds ratio: 2.85, 95% confidence interval: 1.08-7.54) and was less frequently treated as the cause of MRSA infections (odds ratio: 0.15, 95% confidence interval: 0.03-0.73). CONCLUSIONS: SCCmec type IV/CC1/sea+ MRSA was the predominant clone and could be easily transmissible and be capable of colonization. Geriatr Gerontol Int 2023; 23: 744-749.

The Occurrence and Characteristics of Methicillin-Resistant Staphylococcal Isolates from Foods and Containers.

Antimicrobial resistance (AMR) has emerged as an urgent global public health issue that requires immediate attention. Methicillin-resistant staphylococci (MRS) is a major problem, as it may cause serious human and animal infections, eventually resulting in death. This study determined the proportional distribution, genetic characteristics, and antimicrobial susceptibility of mecA- or mecC-carrying staphylococci isolated from food chain products. A total of 230 samples were taken from meat, food, fermented food, and food containers. Overall, 13.9% (32/230) of the samples were identified to have Staphylococcus aureus isolates; of those, 3.9% (9/230) were MRS, with eight mecA-positive and one mecC-positive samples, and 1.3% (3/230) methicillin-resistant Staphylococcus aureus (MRSA). MRSA strains belonging to three sequence types (ST9, ST22, and a newly identified ST), three different spa types (T005, t526, and a newly identified type), and three different SCCmec types (IV, V, and an unidentified SCCmec) were detected. Additionally, eight mecA-positive staphylococcal isolates were identified as S. haemolyticus, S. sciuri, S. simulans, and S. warneri, while the mecC-harboring isolate was S. xylosus. The enterotoxin gene, SEm, was detected at 1.56% in S. aureus, whereas SEq was detected at 0.31%, and SEi was also found in MRSA. Our study emphasizes the importance of enhanced hygiene standards in reducing the risk of occupational and foodborne MRSA infections associated with the handling or consumption of meat, food, and preserved food products.

An Endogenous Staphylococcus aureus CRISPR-Cas System Limits Phage Proliferation and Is Efficiently Excised from the Genome as Part of the SCCmec Cassette.

CRISPR-Cas is an adaptive immune system that allows bacteria to inactivate mobile genetic elements. Approximately 50% of bacteria harbor CRISPR-Cas; however, in the human pathogen Staphylococcus aureus, CRISPR-Cas loci are less common and often studied in heterologous systems. We analyzed the prevalence of CRISPR-Cas in genomes of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in Denmark. Only 2.9% of the strains carried CRISPR-Cas systems, but for strains of sequence type ST630, over half were positive. All CRISPR-Cas loci were type III-A and located within the staphylococcal cassette chromosome mec (SCCmec) type V(5C2&5), conferring ß-lactam resistance. Curiously, only 23 different CRISPR spacers were identified in 69 CRISPR-Cas positive strains, and almost identical SCCmec cassettes, CRISPR arrays, and cas genes are present in staphylococcal species other than S. aureus, suggesting that these were transferred horizontally. For the ST630 strain 110900, we demonstrate that the SCCmec cassette containing CRISPR-Cas is excised from the chromosome at high frequency. However, the cassette was not transferable under the conditions investigated. One of the CRISPR spacers targets a late gene in the lytic bacteriophage phiIPLA-RODI, and we show that the system protects against phage infection by reducing phage burst size. However, CRISPR-Cas can be overloaded or circumvented by CRISPR escape mutants. Our results imply that the endogenous type III-A CRISPR-Cas system in S. aureus is active against targeted phages, albeit with low efficacy. This suggests that native S. aureus CRISPR-Cas offers only partial immunity and in nature may work in tandem with other defense systems. IMPORTANCE CRISPR-Cas is an adaptive immune system protecting bacteria and archaea against mobile genetic elements such as phages. In strains of Staphylococcus aureus, CRISPR-Cas is rare, but when present, it is located within the SCCmec element, which encodes resistance to methicillin and other ß-lactam antibiotics. We show that the element is excisable, suggesting that the CRISPR-Cas locus is transferable. In support of this, we found almost identical CRISPR-Cas-carrying SCCmec elements in different species of non-S. aureus staphylococci, indicating that the system is mobile but only rarely acquires new spacers in S. aureus. Additionally, we show that in its endogenous form, the S. aureus CRISPR-Cas is active but inefficient against lytic phages that can overload the system or form escape mutants. Thus, we propose that CRISPR-Cas in S. aureus offers only partial immunity in native systems and so may work with other defense systems to prevent phage-mediated killing.

Genetic Characteristics of Methicillin-Resistant Staphylococcus argenteus Isolates Collected in the Dutch National MRSA Surveillance from 2008 to 2021.

Staphylococcus argenteus is a recently described member of the Staphylococcus aureus complex (SAC) and is associated with human disease. The frequency and intensity of infections caused by S. argenteus are similar to those of Staphylococcus aureus. S. argenteus can harbor antibiotic resistance genes and a variety of virulence factors analogous to methicillin-resistant S. aureus (MRSA). The aim of our study was to analyze a collection of isolates in the Dutch national MRSA surveillance from January 2008 until March 2021 that were nontypeable by multilocus variable-number tandem-repeat analysis (MLVA). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS) was used for identifying the S. argenteus isolates, and whole-genome sequencing and SeqSphere were used to generate an in-house whole-genome multilocus sequence typing (wgMLST) scheme for typing the isolates. Furthermore, the presence of antibiotic resistance genes, replicons, and virulence genes was determined. Of 52,467 isolates submitted as MRSA from January 2008 until March 2021, 64 isolates (0.12%) were nontypeable with MLVA, and 54 of them were identified with mass spectrometry (MALDI-ToF MS) as S. argenteus. It appeared in retrospect that the first methicillin-resistant S. argenteus (MRSArg) was already submitted in 2008. An in-house-developed S. argenteus wgMLST scheme revealed that S. argenteus isolates clustered in 5 genomic groups which were characterized by distinct MLST types, resistomes, plasmid replicon families, and virulence factors. All but one isolate carried the staphylococcal chromosomal cassette mec (SCCmec) type IV harboring the methicillin resistance gene mecA and represent MRSArg. Most of the isolates with SCCmec subtype IVc(2B) had a trimethoprim resistance gene, dfrG, and harbored a blaZ-carrying plasmid, and most MRSArg isolates have the immune-modulating genes scn and sak. Nine of the 47 isolates carried enterotoxin-encoding genes seg, sei, sem, seo, and seu, which might be able to cause food poisoning. In some persons there was long-term persistence of MRSArg, and there were several genetically related MRSArg isolates in people living in close proximity, suggesting direct human-human transmission. IMPORTANCE We show that MRSArg has been circulating in the Netherlands since at least 2008. Although MRSArg is distinct from MRSA, it has a comparable population structure and carries similar resistance and virulence genes. The Dutch national MRSA surveillance has been expanded to include other methicillin-resistant members of the S. aureus complex, such as S. argenteus and Staphylococcus schweitzeri.

Genotypes of Staphylococcus aureus Clinical Isolates Are Associated with Phenol-Soluble Modulin (PSM) Production.

Phenol-soluble modulins (PSMs) are important S. aureus virulence factors that cause cytolysis, mast cell degranulation, and stimulate inflammatory responses. In this study, PSM production by S. aureus clinical isolates was measured by liquid chromatography/mass spectrometry (LC-MS) and correlated with staphylococcal protein A (spa) type and staphylococcal cassette chromosome mec (SCCmec) type. Of 106 S. aureus clinical isolates, 50 (47.2%) corresponded to methicillin-susceptible S. aureus (MSSA) and 56 (52.8%) to methicillin-resistant S. aureus (MRSA). LC-MS analysis revealed no significant difference in average PSMα3, PSMα4, PSMß2, and δ-toxin production between MSSA and MRSA isolates, but PSMα1, PSMα2, and PSMß1 production were higher in MSSA than MRSA. This study demonstrated that average PSMα1-α4, PSMß1-ß2, and δ-toxin production by SCCmec type II strains was significantly lower than the IV, IVA, and V strains. Most of the SCCmec type II strains (n = 17/25; 68.0%) did not produce δ-toxin, suggesting a dysfunctional Agr system. The spa type t111 (except one strain) and t2460 (except one strain producing PSM α1-α4) did not produce PSMα1-α4 and δ-toxin, while average PSM production was higher among the t126 and t1784 strains. This study showed that the genotype of S. aureus, specifically the spa and SCCmec types, is important in characterizing the production of PSMs.

Molecular analysis and the toxin, MSCRAMM, and biofilm genes of methicillin-resistant Staphylococcus aureus strains isolated from pemphigus wounds: A study based on SCCmec and dru typing.

INTRODUCTION: Pemphigus is a chronic autoimmune blistering disease. Pemphigus blisters can damage the natural skin barrier and increase the risk of life-threatening conditions. Colonization of pemphigus wounds with methicillin-resistant Staphylococcus aureus (MRSA) prolongs wound healing and increases mortality rate. Assessing MRSA prevalence, types, and toxin and adhesion genes can facilitate the detection of MRSA strains which cause infections, selection of appropriate treatments, and healing of pemphigus wounds. This study aimed to determine the SCCmec, the direct repeat unit (dru) types (dts), and the toxin, MSCRAMM, and biofilm genes of MRSA strains isolated from pemphigus wounds. METHODS: In this cross-sectional study, 118 S. aureus isolates were gathered from 118 patients with pemphigus. MRSA detection was performed using the mecA gene. Using the polymerase chain reaction method, all MRSA isolates were assessed for the presence of the sea, seb, sec, tst, eta, pvl, hla, hlb, MSCRAMM, and ica genes. Typing and subtyping were performed through respectively SCCmec typing and dru typing methods. The Bionumerics software was used for analyzing the data and drawing the minimum spanning tree. FINDINGS: From 118 S. aureus isolates, 51 were MRSA. SCCmec typing revealed the prevalence of SCCmec II with a prevalence of 64.7% (33 out of 51 isolates) and SCCmec III with a prevalence of 35.3% (18 out of 51 isolates). Dru typing indicated seven dts, namely dts 10a, 10g, 10m, 13i, 8h, 8i, and 9ca in two main clusters. The dt9ca was a new dru type and was registered in the dru-typing database (www.dru-typing.org). The prevalence rates of the hla, sea, and sec genes in MRSA isolates were respectively 54.9%, 27.4%, and 1.9%, while the hlb, seb, eta, and pvl genes were not detected at all. Only one MRSA with SCCmec III and dt10a carried the tst encoding gene. MSCRAMM gene analysis revealed the high prevalence of the eno (31.3%) and the fib (21.5%) genes. The prevalence rates of the icaA and icaD biofilm formation genes were 3.9% and 5.8%, respectively. There were no significant differences between the two detected SCCmec types and between the two detected dts clusters respecting the prevalence of the encoding genes of virulence factors and MSCRAMMs. CONCLUSION: The toxin genes hla and sea are prevalent among MRSA strains with SCCmec II and III isolated from pemphigus wounds. The most prevalent dts are dt10a and dt10g among MRSA with SCCmec III and dt8h and dt8i among MRSA with SCCmec II.

Increased Incidence and Plasma-Biofilm Formation Ability of SCCmec Type IV Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated From Patients With Bacteremia.

In Japan, Staphylococcal cassette chromosome mec (SCCmec) type IV methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly prominent cause of bacteremia, but the virulence of most of these strains is unclear. We aimed to investigate the relationship between the molecular characteristics and the ability to form biofilms in the presence of blood plasma (plasma-biofilms) of MRSA strains isolated from bloodstream infections. In this study, the molecular characteristics and biofilms of MRSA strains isolated from blood cultures between 2015 and 2017 were analyzed by PCR-based assays, crystal violet staining, and confocal reflection microscopy methods. Among the 90 MRSA isolates, the detection rate of SCCmec type II clones decreased from 60.7 to 20.6%. The SCCmec type IV clone replaced the SCCmec type II clone as the dominant clone, with a detection rate increasing from 32.1 to 73.5%. The plasma-biofilm formation ability of the SCCmec type IV clone was higher than the SCCmec type II clone and even higher in strains harboring the cna or arcA genes. Plasma-biofilms, mainly composed of proteins, were formed quickly and strongly. Our study demonstrated the increased plasma-biofilm formation ability of SCCmec type IV strains.

Antimicrobial Resistance Profiles and Molecular Characteristics of Coagulase-Negative Staphylococci Isolated from Two Tertiary Hospitals Before and 15 Years After Implementation of the Separation of Drug Prescribing and Dispensing Policy of Korea.

This study compared changes in antimicrobial susceptibilities and molecular characteristics of coagulase-negative staphylococci (CNS) between the year 2000 and the year 2014-2015 to evaluate the policy of separating drug prescribing and dispensing in Korea. We obtained 68 CNS clinical isolates from two tertiary general hospitals before (the year 2000; n = 25) and after (the year 2014 - 2015; n = 43) implementation of the separation. Isolates were identified as Staphylococcus capitis, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, and Staphylococcus warneri. When minimal inhibitory concentrations of 14 antimicrobials were applied to isolates, resistance rates to gentamicin and oxacillin in 2000 were significantly higher than in 2014-2015 (p < 0.05). Fifty-seven isolates were methicillin-resistant CNS (MR-CNS), 42 of which were also multidrug resistant; overall, multidrug resistance decreased from 72% in the year 2000 to 55.8% in 2014-2015. Staphylococcal cassette chromosome mec (SCCmec) type III was the dominant type of MR-CNS in the year 2000, while SCCmec type IV was the dominant type in 2014-2015. Twenty-five sequence types (STs) were identified; ST2 appeared most frequently in both periods. After 15 years of implementation of this policy, multidrug resistance as well as methicillin and gentamicin resistance in CNS decreased, but not resistance to other antibiotics. Long-term surveillance at both genotypic and phenotypic levels of various species is necessary for further evaluation of this policy.

Prevalence and molecular characteristics of MRSA nasal carriage among hospital care workers in a tertiary hospital in the Philippines.

BACKGROUND: Hospital-care workers (HCWs) are at risk for MRSA carriage, subsequent infection and potential transmission of nosocomial infection. Epidemiological typing of MRSA among HCWs would provide data that can be used for control measures. METHODS: This is a cross sectional study that involved 92 participants from pediatric and surgery department of a tertiary hospital. Nasal swabs were collected and inoculated onto MRSASelect Chromogenic Media. Samples characterized as MRSA underwent SCCmec typing and detection of Panton Valentine leucocidin (PVL) by PCR. RESULTS: The overall prevalence of MRSA was 13%. Six were from Pediatrics and another six were from Surgery. Seven out of 12 MRSA isolates carried SCCmec type I gene and five isolates carried SCCmec type IV gene. Six samples were found positive for PVL, four of which PVL-SSCmec IV, while the other two isolates were PVL-SCCmec I. The isolates were grouped into four main sequence types (STs) namely ST 1147, ST30, ST5 and ST97. Two samples from both departments were found to be PVL-positive SCCmec I ST 30; PVL-positive SCCmec IV ST 97 was found in two MRSA samples from Pediatrics and PVL-positive SCCmec IV ST 30 from Surgery. CONCLUSION: Data collected from a non-outbreak setting suggest the presence of different clones of MRSA from nasal swabs of HCWs belonging to the Department of Pediatrics and Surgery. The data collected by this study can be used as reference for other succeeding studies on the surveillance of MRSA among HCWs.

Predominance of methicillin-resistant Staphylococcus aureus SCCmec type II-CC5 and SCCmec type IV-CC1/CC8 among companion animal clinical isolates in Japan: Findings from phylogenetic comparison with human clinical isolates.

OBJECTIVES: To characterise the genotypic profiles of methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates from companion animals and to investigate their association with those from humans in Japan. METHODS: Non-duplicated MRSA clinical isolates recovered between July 2016 and January 2018 were analysed. The MRSA isolates were typed by polymerase chain reaction (PCR)-based open reading frame (ORF) typing (POT) scores, SCCmec types, multilocus sequence typing, and virulence gene profiles. Phylogenetic comparison of those isolates with previously described human isolates was performed. RESULTS: Among 56 MRSA isolates (33 cats, 20 dogs and three rabbits), 26 isolates with a POT1 score of 93, SCCmec type II mostly belonged to CC5, including ST5. Twenty-six isolates with a POT1 score of 106, SCCmec type IV showed diversity of STs: 15 isolates belonged to CC8, mainly including ST8, and 11 isolates belonged to CC1, including ST1 and newly identified STs 4768, 4775, and 4779. Two cat isolates were ST8-SCCmec type IV possessing pvl/ACME-arcA, presumed to be the hypervirulent community-associated MRSA (CA-MRSA) clone USA300. Notably, all three rabbit isolates belonged to ST4768. The POT1 score 106 CA-MRSA isolates from animals and humans were divided into two large clusters of CC1 and CC8, where host species-specific sub-clusters were not identified within each cluster. A large cluster of POT1 score 93 healthcare-associated MRSA (HA-MRSA) isolates from animals and humans consisted of sub-clusters formed exclusively by the vast majority of human isolates and those formed by animal and human isolates. CONCLUSION: Companion animals could be potential reservoirs and vehicles for the transmission of CA-MRSA to humans, and could transmit companion animal-adaptive HA-MRSA lineages to humans as their second reservoirs.

Existence of multiple SCCmec elements in clinical isolates of methicillin-resistant Staphylococcus aureus.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) can be classified into hospital-acquired MRSA (HA-MRSA) and community-associated MRSA (CA-MRSA), based on the associated epidemiological risk factors and their SCCmec types. We therefore studied the diversity and distribution of SCCmec elements among MRSA isolates in our region and also evaluated SCCmec typing as a tool for the classification of MRSA. METHODOLOGY: Two hundred isolates of MRSA obtained from various clinical specimens were included. The clinical and demographic details of the patients and the epidemiological risk factors for MRSA acquisition were documented. Multiplex PCR was optimized for all the major SCCmec types (I to V). Subtyping of SCCmec type IV (IVb, IVc, IVd, IVh) was carried out by simplex PCR. RESULTS: Based on epidemiological criteria, CA-MRSA constituted 57  % (114/200) of the the test isolates and HA-MRSA made up 43  % (86/200). The predominant SCCmec type found in our study was type III (62%), followed by type V (52.5%) and type I (47.5%), while type II was carried by a single isolate. Of the 200 isolates, 118 carried multiple SCCmec types and 3 were non-typable. CONCLUSION: The existence of multiple SCCmec types in individual MRSA isolates resulted in our inability to categorize many of these isolates as either CA-MRSA or HA-MRSA as defined by the SCCmec type criterion. LIMITATION: The major limitation of the study was that the SCC mec element of MRSA isolates exhibiting multiple types was not sequenced and hence this finding could not be confirmed.

Prevalence, multidrug resistance and molecular typing of methicillin-resistant Staphylococcus aureus (MRSA) in retail meat from Punjab, India.

OBJECTIVES: This study reports the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in retail meat from Punjab, India. METHODS: Classical microbiological methods were applied to isolate and identify S. aureus isolates. Isolates also underwent Etest. PCR and sequencing were used to identify and characterise antimicrobial resistance genes. MLST, SCCmec and spa typing were performed. RESULTS: A total of 408 meat and 101 swab samples were processed for S. aureus isolation. Phenotypic resistance was highest to penicillin (90.97%), followed by ciprofloxacin (61.80%), tetracycline (45.14%) and erythromycin (11.11%). Isolates from chicken samples showed significantly higher MICs for tetracycline than chevon and pork samples and significantly higher MICs for trimethoprim/sulfamethoxazole and gentamicin than chevon and swab samples (P<0.05). No isolates were phenotypically resistant to vancomycin (MICs of 0.5-2µg/mL). Most isolates (52.78%, 95% CI 44.63-60.93%) were multidrug-resistant and carried resistance genes to penicillin (blaZ), oxacillin (mecA), gentamicin (aacA-aphD), erythromycin (ermB, ermC) and tetracycline (tetK, tetL, tetM). MRSA was only found in chicken samples (2.72%; 4/147). Seven S. aureus (5.07%) were borderline oxacillin-resistant (MIC range 4-8µg/mL). All MRSA were SCCmecV-pvl+-t442, among which three isolates were ST5. Their genotype was mecA+, blaZ+, aacA-aphD+, tetK+, ermC+/-. Among the erythromycin-resistant isolates, 25% were MRSA, of which 12.5% isolates expressed an inducible macrolide-lincosamide-streptogramin B (iMLSB) phenotype. CONCLUSION: These data confirm the presence of ST5-t442-MRSA-SCCmecV-pvl+ and iMLSB MRSA in meat samples, indicating a potential role of meat in the dissemination of multidrug-resistant S. aureus strains and successful MRSA lineages in Punjab.