Carrying Panton-Valentine Leukocidin Research Articles

Panton-valentine leucocidin carrying Staphylococcus aureus causing necrotizing pneumonia inactivates the JAK/STAT signaling pathway and increases the expression of inflammatory cytokines.

Methicillin-resistant Staphylococcus aureus (MRSA) carrying Panton-Valentine leukocidin, a pore-forming toxin, is a common cause of necrotizing pneumonia. However, the early pulmonary inflammatory response following PVL(+) MRSA infection is unknown. The purpose of this study was to use a murine model to determine the effect of PVL(+) MRSA on lung tissues and the expression of cytokines and JAK and STAT mRNA and protein. Mice were randomly divided into 3 groups and intra-nasally treated with PBS (control group), recombinant PVL (rPVL group), and PVL(+) MRSA (PVL group). At 24 and 48h after inoculation, bronchoalveolar lavage fluid (BALF) was tested for cytokine levels, and lung tissues were tested for JAK and STAT mRNA and protein expression, and examined after hematoxylin and eosin staining. Mice infected with the PVL(+) strain became ill, characterized by impaired mobility, hunched posture, ruffled fur, and labored breathing. Lung tissue exhibited tissue necrosis and hemorrhage. BALF levels of IL-8, TNF-α, IFN-γ, IL-12, sICAM-1, and sVCAM-1 were increased in the rPVL or PVL groups, while levels of IL-10 and IL-4 levels were similar among the groups. JAK1 and STAT1 mRNA expression and protein levels were increased in lung tissue from mice infected with PVL(+) MRSA and rPVL. PVL is a significant S. aureus virulence factor, and upregulates the expression of proinflammatory cytokines but does not affect the expression of anti-inflammatory cytokines. The effect of PVL may be due to JAK/STAT pathway activation. Blockade of the JAK/STAT pathway may decrease the severity of PVL(+) MRSA pneumonia.

Methicillin-resistant Staphylococcus aureus strains carrying Panton-Valentine leukocidin genes: clinical and molecular characteristics

Objective To isolate and identify the methicillin-resistant Staphylococcus aureus (MRSA) strains carrying Panton-Valentine leukocidin genes (pvl+ -MRSA) from clinical samples and to further understand their molecular characteristics and infections caused by them. Methods Drug susceptibility test was performed to detect the drug resistance in 259 MRSA strains. pvl+ -MRSA strains were screened out from those MRSA strains using cefoxitin slip test and mecA gene detection by PCR. Multiple PCR and multilocus sequence typing (MLST) were used for SCCmec and ST typing. Pulsed-field gel electrophoresis (PFGE) and cluster analysis were used to understand the genetic and epidemic features of the pvl+ -MRSA strains. Different types of infections and diseases caused by the pvl+ -MRSA strains were analyzed. Results Among the 259 MRSA strains, 51 pvl+ -MRSA strains were identified (19.7%, 51/259), of which 29 and 22 strains were respectively isolated from patients with community-acquired and hospital-acquired infections. ST59-SCCmecⅢ (35.3%, 18/51) was the predominant type of the 51 pvl+ -MRSA strains, followed by ST59-SCCmecⅣ(25.5%, 13/51). But no predominant clone among those strains was revealed by the result of PFGE. Children, young- and middle-aged patients (≤44 years old) had a significantly higher positive rate of pvl+ -MRSA than patients aged ≥45 years (P<0.05). Skin and soft tissue infection (47.1%, 24/51) was the most common disease caused by the pvl+ -MRSA strains (P<0.05), followed by pneumonia (17.6%, 9/51). The pvl+ -MRSA strains showed lower resistance to levofloxacin, gentamycin and rifampicine (7.8%-21.6%). No moxifloxacin-, nitrofurantoin- or linezolid-resistant pvl+ -MRSA strains were identified. Conclusion The rate of pvl+ -MRSA infection is high in the local population. ST59-SCCmecⅢ and ST59-SCCmecⅣ are the predominant types of pvl+ MRSA strains. Children, young- and middle-aged persons are the susceptible population. Skin and soft tissue infection and pneumonia are the common diseases caused by pvl+ -MRSA. Key words: Methicillin-resistant Staphylococcus aureus; Infection; Panton-Valentine leucocidin; Molecular typing; Disease type

Demography and Intercontinental Spread of the USA300 Community-Acquired Methicillin-Resistant Staphylococcus aureus Lineage.

ABSTRACTCommunity-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized worldwide during the 1990s; in less than a decade, several genetically distinct CA-MRSA lineages carrying Panton-Valentine leukocidin genes have emerged on every continent. Most notably, in the United States, the sequence type 18-IV (ST8-IV) clone known as USA300 has become highly prevalent, outcompeting methicillin-susceptible S. aureus (MSSA) and other MRSA strains in both community and hospital settings. CA-MRSA bacteria are much less prevalent in Europe, where the European ST80-IV European CA-MRSA clone, USA300 CA-MRSA strains, and other lineages, such as ST22-IV, coexist. The question that arises is whether the USA300 CA-MRSA present in Europe (i) was imported once or on very few occasions, followed by a broad geographic spread, anticipating an increased prevalence in the future, or (ii) derived from multiple importations with limited spreading success. In the present study, we applied whole-genome sequencing to a collection of French USA300 CA-MRSA strains responsible for sporadic cases and micro-outbreaks over the past decade and United States ST8 MSSA and MRSA isolates. Genome-wide phylogenetic analysis demonstrated that the population structure of the French isolates is the product of multiple introductions dating back to the onset of the USA300 CA-MRSA clone in North America. Coalescent-based demography of the USA300 lineage shows that a strong expansion occurred during the 1990s concomitant with the acquisition of the arginine catabolic mobile element and antibiotic resistance, followed by a sharp decline initiated around 2008, reminiscent of the rise-and-fall pattern previously observed in the ST80 lineage. A future expansion of the USA300 lineage in Europe is therefore very unlikely.

Panton-Valentine leukocidin producing Staphylococcus aureus nasal carriage, in North-Lebanon

ObjectivesWe investigated the prevalence and the risk factors of nasal carriage of Staphylococcus aureus carrying Panton-Valentine leukocidin genes [Sa PVL(+)] in pupils. Study population and methodsTwo hundred and fifty-seven pupils were screened by nasal swabbing. The detection of 16S rRNA, mecA and luk-PV genes was performed by PCR and the risk factors were assessed with the statistical analysis of a questionnaire. ResultsThirty-one percent of pupils were colonized, with 16.4% of isolates carrying the luk-PV gene and 8.8% the mecA gene. Children aged 7years or more and living in a boarding school were the factors promoting nasal carriage 60% of children who presented with an abscess in the previous year were carriers of luk-PV gene Sa. ConclusionThe study revealed a high prevalence of luk-PV gene among methicillin-susceptible strains and a statistically significant correlation between the presence of this gene and presenting with an abscess.

Rapid identification of community-associated methicillin-resistant Staphylococcus aureus by Fourier transform infrared spectroscopy

The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carrying Panton–Valentine leukocidin is a worldwide problem. Their identification is based currently on costly and complicated molecular methods. This article describes a simple method for differentiating CA-MRSA from hospital-associated (HA) epidemic MRSA pulsed-field gel electrophoresis types using Fourier transform infrared (FTIR) spectroscopy. The 47 CA-MRSA isolates included 3 Southwest Pacific (resembling USA1100), 24 CMRSA7 (resembling USA400/MW2), 19 CMRSA10 (resembling USA300), and 1 European ST80, while HA-MRSA were represented by 27, 16, 11, 15, 7, and 8 Canadian epidemic isolates CMRSA1 through CMRSA6 respectively, plus 25 nontyped Canadian HA-MRSA. Principal component analysis (PCA), self-organized maps (SOMs), and the K-nearest neighbor (KNN) method were used to cluster the isolates based on chemometric analysis of FTIR spectra of dried films of stationary-phase cells grown on Que-Bact® Universal Medium No. 2 (Quelab Laboratories, Montreal, QC, Canada). First-derivative normalized data from a single narrow spectral region (1361–1236 cm −1, suggesting differences in protein amide III and nucleic acid phosphodiester contents) allowed 98% correct classification by KNN, 93% by SOMs, and 92% by PCA. FTIR spectroscopic analysis of cells grown on Que-Bact® Universal Medium No. 2 offers a rapid and simple alternative to molecular methods for routine identification of CA-MRSA epidemic isolates.

Prevalence of PVL-Containing MRSA Isolates Among Hospital Staff Nasal Carriers

Staphylococcus aureus (S. aureus) carrying Panton-Valentine leukocidin (PVL) has become a serious global problem. Panton-Valentine leukocidin-positive Staphylococcus aureus can result in several infections, especially cutaneous ones. This study was conducted to determine the frequency of PVL-positive genes in methicillin-resistant Staphylococcus aureus (MRSA) among hospital staff nasal carriers. Collectively, 270 nasal swabs were taken from the personnel of 5 university hospitals in Tehran, Iran. Then polymerase chain reaction (PCR) was used to detect the PVL gene. Among the samples taken, 72 (27%) S. aureus isolates were approved. Among the total isolates, there were 23 MRSA (32%) and 14 (19%) PVL gene-containing cases. This study determined that a prevalence of strains exists among hospital staff members who are continuously in direct contact with patients. This may propose the significance of detecting the carriers and decolonizing them to reduce transmission of S. aureus in the hospital.

Épidémie d’infections cutanées à Staphylococcus aureus porteur des gènes codant la leucocidine de Panton-Valentine en milieu scolaire et familial

Objectives The study objectives were to describe an outbreak of skin infections in school settings, caused by Staphylococcus aureus carrying Panton-Valentine leukocidin genes ( Sa PVL(+)), over a 2-year period. Nasal colonization prevalence was assessed in families where new skin infections occurred, despite a prevention and control strategy. Patients and methods A retrospective investigation of skin infections likely to be related to Sa and prospective monitoring and treatment of new infections occurring in pupils and their family members were implemented in October 2006, following the reporting of Sa PVL(+) abscesses and furuncles in a primary school. Additional nasal screening was performed in families where new skin infections occurred, after an initial systematic screening of Sa PVL(+) nasal carriers. Results On October 31, 2008, 53 patients, accounting for 30 households, had developed 69 skin infections, in four decreasing outbreaks. The cumulative incidence of a first skin infection was 34.6% in primary classes, 21.3% in nursery schools, and 6.5% in the pupils’ family households. Several skin infections were reported in 13 households, and in one of them, all of the seven family members had developed at least one skin infection during follow-up. The estimated frequency of nasal colonization ranged from 14.1% to 19.5% according to successive nasal screenings. Conclusion Early reporting of skin infection clusters is necessary to reinforce the effectiveness of hygiene and prevention measures, and thus limit the risk of a long-lasting outbreak.

Staphylococcus aureus isolated from patients with recurrent furunculosis carrying Panton-Valentine leukocidin genes represent agr specificity group IV

Recurrent furunculosis (RF) caused by Staphylococcus aureus presents a difficult clinical problem and causes significant morbidity. The study aim was to characterise agr groups and detect toxin genes among S.aureus strains isolated from RF patients. Microbiological material was obtained from evacuated furuncules of 44 RF patients. Nasal swabs were obtained from both the RF patients and the controls (150 healthy volunteers with no history of RF). All strains were screened for the presence of lukS/lukF-PV, tst, sea, seb, sec, sed, eta, and etb genes. Moreover, agr specificity groups (I-IV) were identified. Antibiotic-susceptibility tests were performed by disk diffusion method and methicillin susceptibility was verified by mecA gene amplification. The investigated strains were resistant to penicillin, clindamycin, erythromycin, and tetracycline. All showed susceptibility to methicillin. Thirty-five of 44 strains tested were positive for leukocidin lukS/lukF-PV genes and 12/44 for enterotoxin seb gene. The coexistence of PVL genes and seb gene concerned 7/44 strains. The remaining toxin genes were not found. Forty-three strains belonged to agr specificity group IV including all strains with lukS/lukF-PV genes. Nasal carriage of S. aureus was observed in 27/44 (61.3%) RF patients and in 43/150 (28.6%) controls (p = 0.001). In all RF subjects, nasal strains did not differ from those isolated from furuncules in terms of lukS/lukF-PV gene status and agr specificity. To the best of our knowledge, it is the first study that shown such a predominance of agr group IV strains in RF patients.

Identification of ORF636 in Phage φSLT Carrying Panton-Valentine Leukocidin Genes, Acting as an Adhesion Protein for a Poly(Glycerophosphate) Chain of Lipoteichoic Acid on the Cell Surface of Staphylococcus aureus

The temperate phage phiSLT of Staphylococcus aureus carries genes for Panton-Valentine leukocidin. Here, we identify ORF636, a constituent of the phage tail tip structure, as a recognition/adhesion protein for a poly(glycerophosphate) chain of lipoteichoic acid on the cell surface of S. aureus. ORF636 bound specifically to S. aureus; it did not bind to any other staphylococcal species or to several gram-positive bacteria.

Folliculite nécrosante atypique et maladie de Behçet

We report a 24-year-old man with a known Behcet's disease who was lost to follow-up for a year. The patient was admitted for the association of scrotal ulceration and inguinal folliculitis, suggesting a Behcet's disease flare-up. Necrotizing course of the folliculitis led to the diagnosis of skin infection caused by a community-acquired methicillin-resistant Staphylococcus aureus strain, carrying Panton-Valentine leukocidin genes. Bacteriological analysis should be mandatory in the absence of specific criteria for the diagnosis of Behcet's disease.

Community-acquired methicillin-resistant Staphylococcus aureus infections: an emerging threat in Spain

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has not been recognised previously as a cause of MRSA infections in Spain. Nineteen patients carrying Panton—Valentine leukocidin (PVL)-positive MRSA were identified in a Barcelona hospital, of whom 15 were immigrants, mostly from South America. Twelve developed skin and soft-tissue infections. The associated isolates carried the PVL gene and staphylococcal chromosomal cassette (SCC)mecIV. A dominant clone belonging to sequence type (ST)8 and related to the USA300 clone was identified by pulsed-field gel electrophoresis. This clone is emerging in Spain, primarily among immigrants from South America, but dissemination to the native Spanish population could increase.

Prevalence of Staphylococcus aureus carrying Panton—Valentine leukocidin genes among isolates from hospitalised patients in China

Between January 2005 and January 2006, 25 (12.8%) of 195 Staphylococcus aureus isolates were positive for Panton—Valentine leukocidin (PVL) genes in a teaching hospital in Wenzhou, China. Nineteen (11.9%) of 160 hospital-acquired isolates, and six (17.1%) of 35 community-acquired isolates, harboured lukS/F-PV. Six sequence types (ST88, ST239, ST398, ST25, ST30 and ST59) were found among 18 PVL-positive methicillin-resistant isolates with SCCmec types I, III, IIIA or IV. Only ST88 was found among seven PVL-positive methicillin-susceptible S. aureus isolates. The PVL-positive isolates were associated with lung infection, bloodstream infection and soft-tissue pyogenic infection. Overall, there was a high prevalence of PVL genes in genetically diverse S. aureus isolates.

Community-Associated Methicillin-Resistant Staphylococcus aureus Infective Endocarditis with Panton-Valentine Leukocidin Gene in an Injection Drug User with HIV Infection

Reports of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates carrying Panton-Valentine leukocidin (PVL) gene that causes infective endocarditis in injection drug users (IDUs) with human immunodeficiency virus (HIV) infection are rare in the English language literature. We present a case of CA-MRSA infective endocarditis with bilateral septic lung emboli in a previously healthy 45-year-old IDU. This case suggests that PVL gene-positive CA-MRSA should be considered as a potential pathogen in IDUs with infective endocarditis.

Emergence of a new clone carrying Panton-Valentine leukocidin genes and staphylococcal cassette chromosome mec type V among methicillin-resistant Staphylococcus aureus in Greece

Clonal analysis and PCR screening for the presence of Panton-Valentine leukocidin (PVL) genes was performed among 694 methicillin-resistant Staphylococcus aureus (MRSA) cases collected during a 2-y period in Greece. The detection rate of PVL-positive MRSA is high, both in the community and in hospital. Clonal analysis revealed the predominance among the PVL-positive strains of the clonal complex CC80 (ST80-IV) and the emergence of ST377 clone carrying agr1 allele and SCCmec type V.

Infections à Staphylococcus aureus porteurs du gène codant la leucocidine de Panton-Valentine à l'hôpital: quel statut donner à ces souches?

The aim of the present study was to investigate the prevalence Staphylococcus aureus infections carrying Panton-Valentine leukocidin (LPV) genes in our hospital by screening patients that are hospitalised or admitted for consultation, as well as to study the characteristics of these strains and the respectively infected patients. A descriptive and retrospective study over the course of a 14 month period was conducted. The isolates of S. aureus were tested for antimicrobial resistance, in which detection of the virulence gene was performed by way of PCR, such as is the case for gene luk-PV which encoding the LPV. The genetic diversity of the strains carrying gene, luk-PV, was determined by way of pulsed-field gel electrophoresis and by the MLVA (Multiple Loci VNTR Analysis; VNTR, Variable Number of Tandem Repeats) method. 7.14% of the S. aureus isolates carried genes for LPV, which are primarily sourced from surgery, emergency, and outpatient consultation services. The nature of the reported infections is often surface, immediately collected, and more rarely deep. Genotyping revealed three principal clones that were gathering 55% of the strains, which in turn highlighted transmission to the nursing staff. These strains of S. aureus LPV+ have the capacity for diffusion and pathogenicity, which leads to the need to take some specific measures at hospitals: the tracking of the LPV during repeat or deep infections with S. aureus, possibly the search for conveyance and individual measures for the eradication of the strain. Lastly, it is necessary to increase the nursing staff's awareness of the appropriate hygiene measures when they come into contact with these patients.

Fatal community-acquired pneumonia due to Staphylococcus aureus carrying Panton–Valentine leukocidin genes after a stay in Africa

Sir, Staphylococcus aureus is an infrequent cause of community-acquired pneumonia (CAP), accounting for 3–5% of cases. Panton–Valentine leukocidin (PVL) has leukotoxic properties and produces tissue necrosis. PVL-positive strains are associated with highly lethal necrotising pneumonia [1]. We report a fatal case with very rapid clinical course caused by methicillin-susceptible S. aureus after a trip to Africa. A 47-year-old French woman presented to the emergency department with an acute onset of fever, cough, dyspnoea and chest pain. The patient had been well up to 36 h before presentation, when she experienced cough and chills during her return flight to France after a 2-week vacation in Senegal. On the initial examination, the temperature was 40 °C, the heart rate 93 beats/min, the blood pressure 130/80 mmHg and oxygen saturation was 96% in room air. Many pustules were noted on the arms. A chest radiograph was not conclusive (Fig. 1a). Blood and urine were obtained for culture, and the patient was placed on amoxicillin. Over the next few hours, her condition began to deteriorate, with increasing dyspnoea and oxygen requirements. She was transferred to ICU in acute respiratory distress with severe shock. She required intensive management, including intravenous fluids, intubation and ventilation, and vasopressors. An emergency bronchoscopy was undertaken after intubation to clear the airway of large amounts of reddish bronchial secretions, requiring repeated suction and compromising mechanical ventilation. The patient received ceftriaxone and ofloxacin. There was profound hypoxemia with PaO2/FiO2 of 124. Repeated chest radiographs revealed extensive bilateral infiltrates (Fig. 1c, d). The patient’s condition continued to deteriorate with refractory hypoxia and hypotension despite maximal treatment. She

Study on infections caused by Staphylococcus aureus carrying Panton-Valentine leukocidin genes

目的 研究携带Panton-Valentine杀白细胞素(Panton-Valentine leukocidin,PVL)基因金黄色葡萄球菌所致感染类型.方法 利用多重PCR检测金黄色葡萄球菌临床分离株的PVL基因,应用多位点基因序列分型(multilocus sequence typing,MLST)技术对PVL基因阳性的菌株进行序列分型,耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)的SCCmec基因分型采用多重PCR.结果 26株携带PVL基因的金黄色葡萄球菌有13株为ST88,5株为ST239,5株为ST398,ST25、ST30和ST59各1株.20株为医院获得株,主要引起肺部感染和术后伤口化脓性感染;6株为社区感染株,主要引起软组织化脓性感染.7株MSSA全部为ST88,主要引起化脓性感染.而19株MRSA分布在6种ST型中,主要有ST88-SCCmec Ⅲ A、ST239-SCCmec Ⅲ、ST398-SCCmec Ⅳ和ST398-SCCmec Ⅲ.26株菌株分布于14个病区,在产科发生过携带PVL基因的ST88-SCCmec Ⅲ AMRSA克隆株的播散.结论 本院分离的携带PVL基因的金黄色葡萄球菌的序列型主要为ST88、ST239和ST398,既可造成医院感染也可造成社区感染且可能引起克隆株的播散。

High frequency of Panton-Valentine leukocidin genes in invasive methicillin-susceptible Staphylococcus aureus strains and the relationship with methicillin-resistant Staphylococcus aureus in Córdoba, Argentina

In the study presented here, the genetic characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) strains isolated from patients attending hospitals in the city of Córdoba, Argentina, during 1999-2002 were evaluated to determine their genetic relationship with methicillin-resistant S. aureus (MRSA) clones as part of an effort to control the potential emergence of new epidemic MRSA strains. The results showed there is a high frequency of MSSA strains carrying Panton-Valentine leukocidin genes in invasive infections in Córdoba, Argentina, particularly in those occurring in hospital settings. Panton-Valentine leukocidin genes were found in the genomic background of one clone (ST30-N pulsotype) belonging to a successful internationally distributed MSSA lineage (clonal complex 30), which is closely related to the EMRSA-16 pandemic clone. These genes were also detected in the ancestral clone (ST5-M pulsotype) of the most prevalent MRSA epidemic clone causing healthcare-associated infections in this region, known as the Cordobes/Chilean clone. The molecular characterization of circulating MSSA strains, including the detection of Panton-Valentine leukocidin genes, is thus a useful marker for investigating the evolving epidemiology of hospital- and community-acquired MRSA clones.

Spread of Staphylococcus aureus clinical isolates carrying Panton–Valentine leukocidin genes during a 3-year period in Greece

Three collections of Staphylococcus aureus isolates (n = 1,058) were investigated to assess the spread of Panton-Valentine leukocidin (PVL)-producing strains in Greece and their association with skin and soft-tissue infections (SSTIs). The isolates were collected during 2001-2003 from inpatients and outpatients with invasive infections in two distinct geographical areas. Clonal types were identified according to their ClaI-mecA::ClaI-Tn554::pulsed-field gel electrophoresis patterns, and the presence of the lukS-PV and lukF-PV genes was assessed by PCR. In total, 287 (27%) S. aureus isolates carried the PVL genes: 45% of methicillin-resistant S. aureus (MRSA) and 12% of methicillin-sensitive S. aureus (MSSA). All the PVL-positive MRSA isolates belonged to a single clone that was disseminated in the community and hospitals. The PVL-positive MSSA isolates were polyclonal, with 14 of 65 isolates being associated with hospital-acquired infections. The community-acquired isolates were from SSTIs, while the hospital-acquired isolates were associated with surgical wound infections, especially those involving prosthetic devices. Thus, a unique clone of PVL-positive MRSA has spread in both the community and the hospital setting in Greece, and has replaced older clonal types.

The Association between Staphylococcus aureus Strains Carrying Panton-Valentine Leukocidin Genes and the Development of Deep-Seated Follicular Infection

Panton-Valentine leukocidin (PVL) is mainly associated with necrotic suppurative lesions, such as furuncles and abscesses in the skin and subcutaneous tissue, but it has also been isolated from patients with community-acquired, severe, necrotizing pneumonia. However, the clinical manifestations of furuncles caused by PVL-producing Staphylococcus aureus and the role of patients' background are not fully understood. We used polymerase chain reaction amplification to test for the PVL gene in 161 strains of S. aureus isolated from suppurative skin lesions. For all PVL gene-positive strains isolated from furuncles, we analyzed cutaneous manifestations, patient background characteristics, and bacteriological markers, including coagulase types, presence of the mecA gene, and toxin profiles, and we compared these results with those for PVL gene-negative strains. PVL genes were detected in 16 (40%) of the 40 S. aureus strains isolated from furuncles, 2 (28%) of the 7 strains isolated from carbuncles, 1 (14%) of the 7 strains isolated from abscesses, and 1 (5%) of the 20 strains isolated from folliculitis. PVL gene-positive S. aureus usually causes multiple (rather than single) furuncles, and such furuncles are usually associated with more-intense erythema around the lesions. PVL gene-positive strains were isolated from young adults without underlying diseases, whereas PVL gene-negative strains were isolated from patients with various systemic complications, including diabetes, leukemia, and autoimmune diseases. PVL gene-positive S. aureus strains are involved in the development of multiple furuncles with more-intense erythema, particularly in healthy young adults. An understanding of the characteristics of furuncles due to PVL gene-positive strains might be useful for preventing the development of the severe systemic infections.