Homeless Patient With Community-Acquired Methicillin-Resistant Staphylococcus aureus Brain Abscesses.

Brain abscess secondary to community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection is a rare, yet highly fatal disease. This article presents the case of a 45-year-old homeless female with a medical history of bipolar disorder, seizure disorder, and substance use disorder who was admitted with altered mental status. Laboratory tests on admission revealed neutrophil-predominant leukocytosis, elevated inflammatory markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]), and lactic acid. MRI brain demonstrated multiple cerebral abscesses with surrounding edema and sagittal vein thrombosis. The patient was initiated on broad-spectrum antibiotics and underwent a right-sided minimally invasive needle biopsy of the abscess and left frontal craniotomy for abscess evacuation, the culture of which confirmed the diagnosis of MRSA infection. As the patient did not have any hospitalization or procedure in the recent past, a diagnosis of CA-MRSA was made. The patient's clinical status improved following the procedure and antibiotic administration, but she left against medical advice before completing treatment. This case highlights the importance of early recognition and aggressive management of CA-MRSA infections, especially in vulnerable populations such as the homeless.

Molecular Epidemiology of Community-Acquired Methicillin-Resistant Staphylococcus aureus and Clinical Characteristics of Different Sites of Infection.

Purpose: Since community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized, the molecular epidemiology of CA-MRSA in China has been diverse. It is unclear whether different sites of CA-MRSA infection differ in antimicrobial resistance and clinical characteristics. The purpose of this study was to identify the molecular types, virulence factors and antimicrobial resistance of CA-MRSA strains and to analyze the clinical characteristics of different sites of CA-MRSA infection. Methods: 26 CA-MRSA strains were screened from Beijing Chao-Yang Hospital from 2014 to 2022. SCCmec type, MLST type, spa type, Panton-Valentine leukocidin (PVL), hemolysin α (Hla), phenolic soluble regulatory protein α (PSMα), toxic shock syndrome toxin-1 (TSST-1), and enterotoxin (SE) A to E were detected by PCR and gene sequencing. Antimicrobial susceptibility tests and the clinical features of CA-MRSA infection cases were collected for statistical analysis. Results: The predominant type of CA-MRSA was ST59-t437-IV. New non-epidemic types, SCCmec VII, were also found. PVL was seen in 65.4% of CA-MRSA strains and TSST-1 was only be detected in 3.8% of CA-MRSA strain which caused poor prognosis. There were three types of infections: pneumonia (61.5%), infective endocarditis (7.7%), and skin and soft tissue infections (SSTIs) (30.8%). CA-MRSA pneumonia cases were secondary to influenza infection (37.5%). Patients with CA-MRSA-associated infective endocarditis were more likely to have underlying cardiac diseases. Patients with CA-MRSA-associated SSTIs were more likely to have a history of diabetes mellitus, and strains in this group were more susceptible to erythromycin and clindamycin. Conclusion: ST59-t437-IV was the primary CA-MRSA type in our research and in China. We proposed that TSST-1 might be one of the indicators to predict the severity and prognosis of CA-MRSA infection. Different sites of CA-MRSA infection had difference in antibiotics susceptibility testing and underlying diseases of patients. It could provide a new perspective on treating different types of CA-MRSA infection.

Necrotizing pneumonia and purulent meningitis caused by bloodstream infection of CA-MRSA in a child: A rare case report.

Case presentation: We report the case of a girl aged 2 years and 10 months who had fever for 2 days, vomiting, poor mental status for 1 day, and one episode of convulsions. Symptoms and signs: The patient experienced a rapid onset of symptoms with fever, vomiting, and convulsions. Upon physical examination on admission, she presented with the following: temperature 38.6°C; pulse 185 beats/min; respiration 49 beats/min; blood pressure 89/51 mmHg; drowsiness; piebald skin all over her body; rice-grain-sized pustular rashes scattered on the front chest and both lower limbs, protruding from the surface of the skin; bilateral pupils that were equal in size and a circle with a diameter of about 3.0 mm, and slow light reflex; cyanotic lips; shortness of breath; positive for the three-concave sign; a small amount of phlegm that could be heard in both lungs; capillary refill time of 5 s; cold extremities; and a positive Babinski sign. Diagnostic method: A chest computed tomography scan showed multiple nodular and flake-like high-density shadows of varying sizes in each lobe in bilateral lungs, and a cavity with blurred edges could be seen in some nodules. A cranial magnetic resonance imaging examination demonstrated that the hyperintensity of diffusion-weighted imaging could be observed on the left cerebellar hemisphere and left parietal blade. Blood cultures, sputum, cerebrospinal fluid, and bronchoalveolar lavage fluid (BALF) by fiberoptic bronchoscopy all indicated the growth of methicillin-resistant Staphylococcus aureus (MRSA). Treatment methods: After admission, the child was given meropenem combined with vancomycin, cefoperazone sulbactam combined with rifamycin, linezolid (oral) for anti-infection successively, and other adjuvant therapies. Clinical outcomes: The patient recovered clinically and was discharged from our hospital. Recommended readers: Neurology; Respiratory Medicine; Infectious Diseases Department.

Pneumonia Caused by Community-Acquired Methicillin-Resistant Staphylococcus aureus Positive for Exfoliative Toxin A and Secondary to Allergic Bronchopulmonary Aspergillosis.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causes severe pneumonia. Previous reports found that CA-MRSA producing the Panton-Valentine leukocidin (PVL) or toxic shock syndrome toxin-1 (TSST-1) triggered severe necrotizing pneumonia. However, other toxins and genetic factors responsible for CA-MRSA pneumonia are rarely analyzed in Japan. In this study, we performed whole-genome sequencing (WGS) to analyze the clinical features of CA-MRSA genetically. As a result, we identified a strain with a rare sequence-type of MRSA. Herein, we present a case of CA-MRSA pneumonia in a 64-year-old woman. Her condition improved rapidly with vancomycin therapy. Draft WGS led to identifying the genotype and virulence factors and showed that the strain was a rare sequence-type of MRSA with the following characteristics: staphylococcal cassette chromosome mec (SCCmec) type IV, sequence type 121, exfoliative toxin A-positive, and specific staphylococcal protein A type t5110. To the best of our knowledge, a strain with this profile has not been previously reported. Our findings provide new insights into CA-MRSA pneumonia and its genetic and clinical features. Therefore, we recommend accumulating genetic profiles of CA-MRSA pneumonia to identify genetic features and the clinical characteristics of the patients.

Septicaemia with deep venous thrombosis and necrotising pneumonia caused by acute community-acquired methicillin-resistant Staphylococcus aureus in an infant with a three-year follow-up: a case report.

BACKGROUND: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a common pathogen that usually causes bacteraemia, osteomyelitis, as well as skin and soft tissue infections. However, deep venous thrombosis (DVT) and necrotising pneumonia are rare in infants. CASE PRESENTATION: We report the case of a one-month-five-day-old girl who was hospitalised for DVT and necrotising pneumonia due to septicaemia associated with Staphylococcus aureus. She recovered after treatment with intravenous antibiotics and multiple anticoagulant therapy, but DVT persisted at the three-year follow-up. Collateral circulation around the DVT was well-formed. Post thrombotic syndrome was not observed. CONCLUSIONS: Staphylococcus aureus complicated by DVT and necrotising pneumonia is rare and can be successfully treated.

Retropharyngeal Abscess Caused by Community-Acquired MRSA USA300 Clone in a 1-Year-Old Japanese Girl.

We describe a domestic case of retropharyngeal abscess (RPA) in a child caused by a community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolate that was genetically proven to be the USA300 clone (sequence type [ST]8-SCCmec IVa-Panton-Valentine leukocidin [PVL]). USA300 generally has a PVL gene, an epidemiologic association with severe and recurrent skin and soft tissue infection, and is the leading cause of RPA in the United States. A 1-year-old previously healthy girl visited the emergency department with fever, sore throat, and a difficulty in moving her neck. The patient had no recent medical exposure or history of travel abroad. Enhanced computed tomography revealed a bulky low-density area with ring enhancement in the retropharyngeal and right parapharyngeal spaces. MRSA was isolated from pus obtained from surgical drainage, and antibiotics were continued for a total of 21 days. MRSA was analyzed by whole genome sequencing and compared with representative USA300 isolates. The strain was typed as ST8-t9829-SCCmec IVa with PVL and arginine catabolic mobile element, and its sequence was 99.8% identical to USA300 isolates. The present case supports the possibility that USA300 is potentially spreading in the Japanese community and raises the possibility of USA300 invasive infections without a clear route of infection.

Sub-Inhibitory Concentrations of Oxacillin, but Not Clindamycin, Linezolid, or Tigecycline, Decrease Staphylococcal Phenol-Soluble Modulin Expression in Community-Acquired Methicillin-Resistant Staphylococcus aureus.

Staphylococcus aureus (SA) is a major human pathogen producing virulence factors, such as Panton-Valentine-leucocidin (PVL), alpha-hemolysin (Hla), and phenol-soluble-modulins alpha (PSMα), including delta-hemolysin (Hld). Unlike oxacillin, clindamycin and linezolid subinhibitory concentrations (sub-MIC) display an anti-toxin effect on PVL and Hla expression. Few studies have investigated PSMα and Hld expression modulation by antibiotics. Herein, we assessed the effect of antibiotic sub-MIC on PSMα1 and Hld expression for 4 community-acquired methicillin-resistant SA (CA-MRSA), 2 strains belonging to USASA300 and 2 strains belonging to ST80 European clone. SA were grown under oxacillin, clindamycin, linezolid, or tigecycline. After incubation, culture pellets were used for the determination of psmα1, pmtB, pmtR mRNA, and RNAIII levels by relative quantitative RT-PCR. PSMα1 and Hld expressions were measured in supernatant using high-performance-liquid-chromatography coupled to mass-spectrometry (HPLC-MS). Oxacillin sub-MIC reduced PSMα1 and Hld production, partially related to mRNA variations. For other antibiotics, effects on toxin expression were strain or clone dependent. Antibiotic effect on mRNA did not always reflect protein expression modulation. Variations of pmtB, pmtR mRNA, and RNAIII levels were insufficient to explain toxin expression modulation. Altogether, these data indicate that PSMα and Hld expressions are modulated by antibiotics (potential anti-toxin effect of oxacillin) differently compared to PVL and Hla. IMPORTANCE Staphylococcal toxins play an important role in the physiopathology of staphylococcal infections. Subinhibitory concentrations (sub-MIC) of antibiotics modulate in vitro toxins expression in S. aureus: clindamycin (CLI) and linezolid (LIN) display an anti-toxin effect on Panton-Valentine leucocidin and alpha-hemolysin production, while oxacillin (OXA) has an inducing effect. Few studies have focused on the modulation of phenol-soluble modulins alpha (PSMα) including delta-hemolysin expression by sub-MIC antibiotics. The aim of the present study was to investigate the effects of sub-MIC antibiotics on the expression of PSMα toxins for 4 community-acquired methicillin-resistant S. aureus (CA-MRSA) clinical isolates. The data presented herein confirm that OXA sub-MICs constantly inhibit PSMα production for CA-MRSA. Certain strains of S. aureus are highly sensitive to sub-MICs of protein synthesis inhibitory agents, resulting in an important increase of mRNA levels to overcome the intrinsic ribosome blockage ability of these antibiotics, eventually translating in increased expression of toxins.

First Report of Fatal Infection Caused by Community-acquired Methicillin-resistant Staphylococcus aureus USA300 Clone in a Collegiate Athlete.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is prevalent around the world and is a causative agent of skin and soft tissue infections in healthy individuals. Particularly, Panton-Valentine leukocidin (PVL)-positive CA-MRSA strains occasionally cause life-threatening infections, such as septic pulmonary emboli (SPE) and infectious endocarditis. However, severe infections caused by PVL-positive CA-MRSA strains have rarely been reported in Japan. For the first time, this study reports the case of a 20-year-old Japanese college athlete with life-threatening PVL-positive CA-MRSA USA300 clone infection, including sepsis, SPE, and skin and soft tissue infections with iliofemoral deep venous thrombosis.

Two Cases of Intrafamilial Transmission of Community-Acquired Methicillin-Resistant Staphylococcus aureus Producing Both PVL and TSST-1 Causing Fatal Necrotizing Pneumonia and Sepsis.

INTRODUCTION: Staphylococcus aureus produces numerous toxins, such as toxic shock syndrome toxin 1 (TSST-1) and Panton-Valentine leukocidin (PVL). We isolated community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains producing both TSST-1 and PVL isolated from severe necrotizing pneumonia cases in a Nepali family. Detection of these CA-MRSA strains is rare in the world, and infection with these strains can take a rapidly progressive and lethal course. In this study, we traced the clinical course of this case and conducted a genetic analysis of the isolated strains. CASE REPORT: We described 2 familial cases (a 20-year-old male and 61-year-old female) of severe necrotizing pneumonia caused by CA-MRSA with the TSST-1 and PVL genes. A 20-year-old Nepalese male was admitted to our hospital after a 3-day history of high fever and coughing. Despite resuscitation efforts, he died of multiple organ failure. A 61-year-old Nepalese female was admitted to our hospital with a complaint of high fever and dyspnea for 1 day. She was the grandmother of the male subject and mostly stayed at his residence in Japan. We administered intravenous antibiotics, including anti-MRSA antibiotics, and she improved in 2 weeks. The sequence type of the isolates was ST22/SCCmec type IVa, and the spa type was t005. The virulence genes detected were as follows: PVL gene (lukSF-pv), TSST-1 gene (tst-1), sec, seg, sei, sel, sem, sen, seo, and seu. ST22 was not the dominant CA-MRSA clone type in Japan. Some of the reports demonstrated that PVL-/TSST-1-positive ST22-MRSA strains are prevalent in Nepal. Therefore, the MRSA strains were thought to be acquired from Nepal. CONCLUSION: These cases highlight the emergence of TSST-1- and PVL-positive CA-MRSA infection and its association with life-threatening community-acquired necrotizing pneumonia. Clinicians should note the possibility of introducing MRSA strains from abroad and be aware of this illness to initiate appropriate treatment.

Observational study of skin and soft-tissue Staphylococcus aureus infection in patients infected with HIV-1 and epidemics of Panton-Valentine leucocidin-positive community-acquired MRSA infection in Osaka, Japan.

BACKGROUND: In patients infected with human immunodeficiency virus (HIV)-1 at our hospital, we observed increases in skin and soft-tissue infections (SSTIs) by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Therefore, we analyzed factors related to CA-MRSA infection and performed a molecular epidemiological investigation. METHODS: HIV-1-infected patients were diagnosed with SSTIs related to S. aureus between 2007 and 2017, and MRSA was classified into community and hospital-acquired types according to published criteria. Information was collected retrospectively from clinical records, and multivariate analysis by logistic regression was performed concerning factors related to CA-MRSA infection. We evaluated the staphylococcal cassette chromosome mec (SCCmec) type, multilocus sequence type, and the presence of genes encoding Panton-Valentine leucocidin (PVL) in 27 MRSA samples isolated during and after 2015. RESULTS: We found 218 episodes of SSTIs in 169 patients, and among initial episodes of SSTIs, the MRSA ratio was higher from 2015 to 2017 relative to that from 2007 to 2014 (88% vs. 44%; p < 0.0001). Multivariate analysis showed that in men having sex with men [MSM; odds ratio (OR): 13] and exhibiting onset during and after 2015 (OR: 5.4), CD4+ cell count ≥200 cells/µL (OR: 5.6) and the presence of lesions in the lower abdomen or buttocks (OR: 9.5) were independent factors related to CA-MRSA infection. Additionally, PVL+/ST8/SCCmec type IV MRSA was the predominant pathogen (22 cases; 81%). CONCLUSIONS: These data describe an increased prevalence of SSTIs due to PVL-positive ST8-MRSA-IV, not previously considered epidemic in Japan, in MSM infected with HIV-1 in Osaka, Japan.

Current status of Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus isolated from patients with skin and soft tissue infections in Japan.

The USA300 clone, which produces Panton-Valentine leukocidin (PVL), is a major pathogenic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone that causes intractable skin infections. Recently, PVL-positive CA-MRSA, including USA300 clones, have emerged in both communities and hospitals in Japan. To prevent an outbreak of PVL-positive MRSA, infected patients should be treated with effective antimicrobial agents at community clinics. Herein, we investigate molecular epidemiological characteristics of PVL-positive MRSA isolated from outpatients with skin and soft tissue infections (SSTI), which are common community-onset infectious diseases. The detection rate of MRSA was 24.9% (362 strains) out of 1455 S. aureus strains isolated between 2013 and 2017. Among the MRSA strains, 15.5% (56 strains) were PVL-positive strains and associated with deep-seated skin infections. Molecular epidemiological analyses of PVL-positive MRSA showed that USA300 was the predominant clone (53.6%, 30 strains) and was identified in Kanto (18 strains), Kagawa (nine strains), Tohoku (two strains) and Hokkaido (one strain). Notably, minocycline and fusidic acid were effective against all PVL-positive MRSA strains. Hence, our data reveals the current status of PVL-positive MRSA isolated from patients with SSTI in Japan. Continuous surveillance of CA-MRSA is necessary to monitor latest prevalence rates and identify effective antimicrobial agents for PVL-positive MRSA strains.

A risk as an infection route: Nasal colonization of methicillin-resistant Staphylococcus aureus USA300 clone among contact sport athletes in Japan.

Panton-Valentine leukocidin (PVL)-positive USA300 clone is a highly pathogenic and global epidemic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone. Athletes are particularly vulnerable to CA-MRSA infection because of the frequency of skin trauma, close-contact situations, and sharing of equipment that is customary in the athletic setting. We experienced a case of Japanese collegiate football player with septic pulmonary emboli secondary to infectious iliofemoral deep venous thrombosis caused by the USA300 clone. Here, we screened the nasal carriage of USA300 clone colonization among asymptomatic teammate of the patient to elucidate the infection route. Among 69 nasal samples, CA-MRSA strains were found in 5.8% (four samples). Molecular epidemiological analyses showed that three of the CA-MRSA strains were USA300 clone. Furthermore, pulsed-field gel electrophoresis revealed that all nasal USA300 clones showed 100% identity with the USA300 clone isolated from their teammate with critical infection. Our findings indicate that nasal colonization of the PVL-positive CA-MRSA, especially USA300 clone, pose a threat among contact sport athletes in Japan likewise other countries. An immediate infection control strategy for contact sport athletes is necessary to prevent outbreaks of PVL-positive CA-MRSA infections.

Antibiotic Management and Antibiotic Resistance in Hand Infections.

The rates of methicillin-resistant infections in the hand and upper extremity approach 50% in many facilities. In addition, multidrug resistance is beginning to include clindamycin. This article discusses the history, prevalence, and treatment of both community-acquired and health care-associated methicillin-resistant Staphylococcus aureus in regard to hand infections.

An outbreak of severe infectious diseases caused by methicillin-resistant Staphylococcus aureus USA300 clone among hospitalized patients and nursing staff in a tertiary care university hospital.

The USA300 clone, which produces Panton-Valentine leukocidin (PVL), is a major highly pathogenic community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone that is spreading throughout the world. Although the prevalence of the USA300 clone in Japan was very limited a decade ago, its incidence has been increasing in both community and hospital settings in recent years. There is great concern that the USA300 clone will cause more complicated diseases and become a serious threat to immunocompromised patients in hospital settings. Here, we report an outbreak of severe infectious diseases in a tertiary care university hospital involving the incidence of deep infections, including bacteremia, and continuous and frequent isolation of MRSA strains for five months from six patients and a healthy nursing staff member in the same ward. The genotype of all MRSA isolates was identical to that of the USA300 clone. Furthermore, pulsed-field gel electrophoresis analysis indicated that all MRSA had the same patterns. These data demonstrate that a USA300 clone outbreak had occurred in the hospital. Fortunately, this outbreak was terminated subsequent to the interventions of the infection control team and all patients recovered following the appropriate therapies. Our report demonstrates that patients carrying highly pathogenic CA-MRSA have the potential to become a source of nosocomial outbreaks that can spread to healthy healthcare workers. Therefore, stricter standard precautions should be applied for all patients at the time of admission to prevent such nosocomial outbreaks.

Clonal change of methicillin-resistant Staphylococcus aureus isolated from patients with impetigo in Kagawa, Japan.

Recently, the USA300 clone, which is a Panton-Valentine leukocidin (PVL)-positive clonal complex 8-staphylococcal cassette chromosome mec type IV (CC8-IV) community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strain, emerged in community and hospital settings in Japan. Hence, clonal types of CA-MRSA strains are predicted to be changing. Nonetheless, long-term surveillance of CA-MRSA has not been conducted in Japan. Here, we investigated the transition and current status of CA-MRSA strains isolated from outpatients with impetigo; the samples were collected between 2007 and 2016 in Kagawa, Japan. The detection rate (22.8%, 488/2139 strains) of MRSA slightly decreased in these 10 years. Molecular epidemiological analyses showed that the prevalence of the CC89-II clone, which is a typical CA-MRSA genotype of causative agents of impetigo, significantly decreased from 48.0% (48/100 strains) in 2007-2009 to 21.9% (16/73 strains) in 2013-2016. By contrast, a non-USA300 CC8-IV clone, which is a highly pathogenic CA-MRSA/J clone, significantly increased in prevalence from 9.0% (9/100 strains) to 32.9% (24/73 strains). The prevalence of PVL-positive CA-MRSA strains increased annually from 2012 (0%) to 2015 (6.7%), whereas only one of these strains turned out to be the USA300 clone. Antibiotic susceptibility data revealed that the rates of resistance to gentamicin and clindamycin among CA-MRSA strains decreased along with the decreased prevalence of the CC89-II clone and increased prevalence of the CA-MRSA/J clone. Our data strongly suggest that the clonal types and antibiotic susceptibility of CA-MRSA isolated from patients with impetigo dramatically changed during the last 10 years in Japan.

A case of acute septic arthritis of the hip joint caused by Panton-Valentine leukocidin-positive ST772 community-acquired methicillin-resistant Staphylococcus aureus.

Acute septic arthritis (ASA) caused by Staphylococcus aureus can lead to fulminant arthritis and cause permanent joint destruction. In particular, infection caused by methicillin-resistant Staphylococcus aureus (MRSA) becomes intractable and severe owing to limitation of therapeutic drugs. Here, we report the case of a young patient with ASA without any record of overseas travel, who was infected by the Panton-Valentine leukocidin-positive Bengal-Bay clone, which is a predominant community-acquired MRSA in India.

Clonal clusters and virulence factors of methicillin-resistant Staphylococcus Aureus: Evidence for community-acquired methicillin-resistant Staphylococcus Aureus infiltration into hospital settings in Chennai, South India.

Background and Objective: Staphylococcus aureus is one of the major pathogens of nosocomial infections as wells as community-acquired (CA) infections worldwide. So far, large-scale comprehensive molecular and epidemiological characterisation of S. aureus from very diverse settings has not been carried out in India. The objective of this study is to evaluate the molecular, epidemiological and virulence characteristics of S. aureus in both community and hospital settings in Chennai, southern India. Methods: S. aureus isolates were obtained from four different groups (a) healthy individuals from closed community settings, (b) inpatients from hospitals, (c) outpatients from hospitals, representing isolates of hospital-community interface and (d) HIV-infected patients to define isolates associated with the immunocompromised. Antibiotic susceptibility testing, multiplex polymerase chain reactions for detection of virulence and resistance determinants, molecular typing including Staphylococcal cassette chromosome mec (SCCmec) and agr typing, were carried out. Sequencing-based typing was done using spa and multilocus sequence typing (MLST) methods. Clonal complexes (CC) of hospital and CA methicillin-resistant S. aureus (MRSA) were identified and compared for virulence and resistance. Results and Conclusion: A total of 769 isolates of S. aureus isolates were studied. The prevalence of MRSA was found to be 7.17%, 81.67%, 58.33% and 22.85% for groups a, b, c and d, respectively. Of the four SCCmec types (I, III, IV and V) detected, SCCmec V was found to be predominant. Panton-Valentine leucocidin toxin genes were detected among MRSA isolates harbouring SCCmec IV and V. A total of 78 spa types were detected, t657 being the most prevalent. 13 MLST types belonging to 9 CC were detected. CC1 (ST-772, ST-1) and CC8 (ST238, ST368 and ST1208) were found to be predominant among MRSA. CA-MRSA isolates with SCCmec IV and V were isolated from all study groups including hospitalised patients and were found to be similar by molecular tools. This shows that CA MRSA has probably infiltrated into the hospital settings.

Comparative analysis of methicillin-resistant Staphylococcus aureus isolated from outpatients of dermatology unit in hospitals and clinics.

Community-onset methicillin-resistant Staphylococcus aureus (CO-MRSA) is a causative agent of intractable skin infections. In general, clinical symptoms of hospital outpatients with skin infections are severer than those of clinic patients. Hence, molecular epidemiological features of the CO-MRSA strains from hospital outpatients are predicted to be different from those of clinic patients. Here, we conducted a comparative analysis for CO-MRSA isolates from outpatients with impetigo in hospitals and clinics located in the same district of Tokyo, Japan. Incidence of MRSA infection was higher in hospital outpatients (21.5%, 20/93 isolates) than in clinic patients (14.5%, 121/845 isolates). The resistance rate to clindamycin, which is a common topical antimicrobial agent in dermatology, in the isolates from hospital outpatients (60.0%) was higher than those from clinic patients (31.4%). Proportion of the staphylococcal cassette chromosome (SCC) mec type II, which is a representative type of hospital-acquired MRSA in Japan, in the isolates from hospital outpatients (65.0%) was significantly higher than those from clinic patients (30.6%) (P < 0.01). Multilocus sequence typing showed that the clonal complex 89-SCCmec type II (CC89-II) clone, which exhibits clindamycin resistance, was the most predominant (55.0%) in the isolates from hospital outpatients. On the other hand, all CC8-IV, CC121-V, and CC89-V clones accounted for 60% in clinic patients were susceptible to clindamycin. Our findings suggested that the clindamycin-resistant CC89-II CO-MRSA clone might be more related to skin infections in hospital outpatients than clinic patients.

Rapidly Progressive Multiple Cavity Formation in Necrotizing Pneumonia Caused by Community-acquired Methicillin-resistant Staphylococcus aureus Positive for the Panton-Valentine Leucocidin Gene.

A 66-year-old man was transferred to our hospital for pneumonia that was resistant to sulbactam/ampicillin and levofloxacin therapy. Chest computed tomography showed the rapidly progressive formation of multiple cavities. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated, and the patient was diagnosed with necrotizing pneumonia caused by community-acquired MRSA (CA-MRSA). The MRSA strain had type IV staphylococcus cassette chromosome mec and genes encoding Panton-Valentine leucocidin (PVL). CA-MRSA necrotizing pneumonia with the PVL gene is rare; only three cases have been previously reported in Japan. We administered anti-MRSA antibiotics and the patient achieved complete clinical and radiological improvement.