Treatment and prevention of community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections

ABSTRACT:   Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a pathogen in the community with a range of clinical manifestations. Although skin and soft tissue infections (SSTIs) are the most common presentation, invasive and more virulent disease has been observed. Colonization and infection with CA-MRSA can occur in individuals with no prior healthcare exposures but also in distinct groups whose common characteristic appears to be close person-to-person contact. Outbreaks with CA-MRSA have occurred in day care centers, athletic teams, and prisons, and transmission has been documented among family members and within the hospital. Treatment of SSTIs involves incision and drainage, oral or parenteral antibiotic therapy, or topical therapy. Healthcare practitioners in outpatient and inpatient settings need to be familiar with prevention and treatment strategies for CA-MRSA.     

Superficial community-acquired skin infections: prevalence of bacteria and antibiotic susceptibility in France

Objective  Evaluation of the susceptibility to currently used antibiotics of bacteria, particularly S. aureus isolated from superficial community- acquired skin infection and to compare results with those from an earlier study.
Methods  Every dermatologist in community practice participating in the study was asked to include the first two patients consulting them for superficial cutaneous bacterial infection. Swab specimens collected from the skin infection were sent to a central laboratory.
Results  The dermatologist enrolled 390 patients in the study. The rate of positive culture was 49%, 259 bacterial strains were isolated. S. aureus was the major species (56.8% of all isolated strains). S. aureus was resistant to methicillin in 4%. All strains of S. aureus were susceptible to pristinamycin and mupirocin.
Conclusions  The results of the two epidemiological studies of superficial community acquired skin infections with a comparable methodology at a 6-year interval demonstrated that the prevalence of CA-MRSA skin infection remained low in this setting.     

Community-associated methicillin-resistant Staphylococcus aureus skin infections in the tropics

Skin and soft tissue infections (SSTI) caused by Staphylococcus aureus are very common, particularly in children, in tropical regions. The proportion of S aureus SSTI caused by community-associated methicillin-resistant S aureus (CA-MRSA) varies according to region, but is up to 25% in some areas. There are diverse CA-MRSA clones, including several that harbor Panton-Valentine leukocidin. Key predisposing factors for staphylococcal infections are scabies infestation, overcrowding, poor hygiene, and inadequate water supplies. In the setting of a community outbreak of staphylococcal SSTI, interventions intended to improve personal and community hygiene are likely to be the most practical, effective, and achievable. Options for oral treatment of clinical infections caused by CA-MRSA include clindamycin and trimethoprim-sulfamethoxazole. Although rapid diagnostics are now available, and 2 vaccines have reached clinical trials, neither of these is likely to be of use in tropical, developing regions in the near future.     

皮肤屏障与病毒感染的研究进展

病毒感染性皮肤病在人群中具有患病率高、分布广的特点,其发病具有两大关键因素：即屏障破坏与病毒感染宿主细胞。本文就近年来皮肤在抗病毒方面发挥屏障功能以及病毒感染的机制研究进展进行综述。     

Molecular characteristics of methicillin‐resistant Staphylococcus aureus isolated from skin and soft tissue infections collected in the Japanese nationwide surveillance

Skin and soft tissue infections (SSTI) are a common infection among both outpatients and inpatients. The most frequently isolated bacterium in SSTI was Staphylococcus aureus, a quarter of which was methicillin‐resistant S. aureus (MRSA). In this study, to investigate molecular epidemiology of the 141 MRSA strains collected in the Japanese nationwide surveillance, we performed multiplex real‐time polymerase chain reaction to detect staphylococcal cassette chromosome mec (SCCmec) type and virulence genes. The percentage of SCCmec types I, II, III and IV was 1.4%, 52.5%, 5.7% and 40.4%, respectively. According to the SCCmec type, we classified the strains into health‐care‐associated (HA)‐MRSA (n = 84) and community‐associated (CA)‐MRSA (n = 57). Among the virulence genes, the percentage of enterotoxin C gene‐positive strains was significantly higher in CA‐MRSA than in HA‐MRSA. No significant differences were detected between the two groups in terms of antibiotic susceptibility and patients’ background information, classification of SSTI or symptoms of SSTI.     

Emergence of two populations of methicillin-resistant Staphylococcus aureus with distinct epidemiological, clinical and biological features, isolated from patients with community-acquired skin infections

BACKGROUND: Community-acquired skin and soft-tissue infections due to methicillin-resistant Staphylococcus aureus (MRSA) are an emerging clinical and epidemiological problem. OBJECTIVES: To characterize community-acquired skin infections caused by S. aureus, and especially MRSA. METHODS: From November 1999 to December 2003, we conducted in a French hospital a prospective epidemiological, clinical and bacteriological study of skin infections acquired in the community, applying strict criteria for true community-acquired MRSA (CA-MRSA) and health-care-associated MRSA (HCA-MRSA). RESULTS: One hundred and ninety-seven patients had 207 skin infections (154 primary and 53 secondary infections). Twenty-two (11%) patients had skin infections caused by MRSA. The incidence of MRSA skin infections acquired in the community rose from 4% in 2000 to 17% in 2003, but the increase was not statistically significant. Six patients (3%) were infected by CA-MRSA and 15 (8%) by HCA-MRSA; one patient was lost to follow-up and could not be classified. CA-MRSA and HCA-MRSA had different epidemiological, clinical and biological characteristics. CA-MRSA infections were more severe than HCA-MRSA infections: all the CA-MRSA infections (six of six, 100%) required surgical treatment, compared with only two (15%) of 13 with HCA-MRSA infection (P < 0.001). CA-MRSA all belonged to the same clonal strain, harbouring an agr type 3 allele and the Panton-Valentine leucocidin genes (not detected in HCA-MRSA) and possessing a specific antibiotype. CONCLUSIONS: Two populations of MRSA causing skin infections are emerging in the French community, with distinct epidemiological, clinical and biological characteristics.     

Staphylococcus aureus skin colonization is promoted by barrier disruption and leads to local inflammation

Experimental mouse models of bacterial skin infections that have been described show that pathogenic microorganisms can readily invade the epidermis and dermis to produce localized infections. We used an epicutaneous mouse skin infection model to determine how the level of barrier disruption by tape‐stripping correlates with persistence of Staphylococcus aureus skin colonization, concomitant induction of cutaneous inflammation and infection. Furthermore, we investigated how murine skin responds to S. aureus colonization in a physiologic setting by analysing proinflammatory cytokines and antimicrobial peptides in mouse skin. We show that previous cutaneous damage allows skin inflammation to develop and favours S. aureus persistence leading to cutaneous colonization, suggesting an interdependence of cutaneous bacteria and skin. Our study suggests that skin barrier defects favour S. aureus skin colonization, which is associated with profound cutaneous inflammation.     

Recalcitrant eosinophilic pustular folliculitis of Ofuji with palmoplantar pustulosis: dramatic response to narrowband UVB phototherapy

Eosinophilic pustular folliculitis of Ofuji is a recalcitrant disease typified by non‐infective eosinophilic spongiosis involving the infundibular region of the hair follicle. We present a case of a 49‐year‐old Chinese man with known palmoplantar pustulosis and acrodermatitis continua of Hallopeau which was promptly resolved with methotrexate therapy. He returned with an erythematous papulopustular eruption with coalescence to annular plaques, occurring over the face, chest and back with active palmoplantar pustulation. Histology from skin biopsy of the palmar lesion was in keeping with palmoplantar psoriasis, while biopsy of the facial and truncal lesions revealed florid perifollicular eosinophilic congregation diagnostic of eosinophilic pustular folliculitis of Ofuji. Indomethacin was initiated with partial improvement of lesions with cyclical flares. A trial of narrowband ultraviolet‐B phototherapy at a frequency of thrice weekly achieved sustained clearance of both eosinophilic pustular folliculitis and palmoplantar lesions. Indomethacin was tailed down and eventually discontinued with maintenance of narrowband ultraviolet‐B therapy; this achieved successful control of the disease.     

北京地区儿童皮肤感染金黄色葡萄球菌的耐药研究

目的 分析儿童皮肤感染金黄色葡萄球菌的耐药现状及社区获得性耐甲氧西林金黄色葡萄球菌的流行情况。方法 对600例感染性皮肤病患儿皮损分泌物进行细菌培养。应用琼脂稀释法检测抗生素及环丙沙星对培养出的金黄色葡萄球菌的最小抑菌浓度。结果 600例患儿皮损共培养出金黄色葡萄球菌451株，对13种抗生素及环丙沙星的药敏试验结果显示，对青霉素耐药率为93.8%，对红霉素耐药率为87.6%，对克林霉素为71.6%，对四环素、氯霉素、庆大霉素和环丙沙星的耐药率依次为37.3%，13.3%，6.4%和2.2%，对苯唑西林、头孢唑啉、头孢呋辛和莫匹罗星耐药率分别为1.6%，0.4%，0.2%和0.2%，未发现头孢曲松、万古霉素和夫西地酸耐药菌株。结论 儿童社区获得性耐甲氧西林金黄色葡萄球菌分离率为1.6%。治疗社区来源的皮肤金黄色葡萄球菌感染性皮肤病，全身治疗首选耐青霉素酶的半合成青霉素和头孢菌素，外用治疗可选择莫匹罗星或夫西地酸。     

Relationship between quinolone use and resistance of Staphylococcus epidermidis in patients with acne vulgaris

Staphylococcus epidermidis is a bacterium known to inhabit the skin. In treatment of acne vulgaris, the cutaneous milieu is exposed to oral or topical antimicrobials. We previously reported that the antimicrobial resistance of Cutibacterium acnes isolated from acne patients is affected by antimicrobial use. The aim of this study was to investigate the relationship between quinolone use and resistance in skin bacteria, particularly S. epidermidis, from acne patients. A total of 92 and 87 S. epidermidis strains isolated from clinic patients and hospital outpatients with acne vulgaris, respectively, were tested. No significant difference was found between the prevalence of methicillin‐resistant S. epidermidis (MRSE) strains from clinic patients (37.0%) and hospital outpatients (39.1%). The MRSE strains (20.6%, 14/68 strains) showed a significantly higher ratio of high‐level levofloxacin resistance (minimum inhibitory concentrations were 64 to ≥256 μg/mL) compared with methicillin‐susceptible S. epidermidis strains (2.7%, 3/111 strains) (P < 0.01). The rate of levofloxacin resistance in C. acnes strains, which were isolated from the same samples of acne patients, showed a strong positive correlation with that in S. epidermidis strains (r = 0.93, P < 0.01). The high‐level levofloxacin‐resistant strains were frequently found in patients with history of quinolone use compared with those without (P < 0.01). Our data showed for the first time that antimicrobial administration for acne treatment affects the antimicrobial resistance in not only C. acnes but also S. epidermidis. Thus, caution should be exercised in antimicrobial use for acne treatment to prevent increasing antimicrobial resistance in these species.     

Correlation of serum procalcitonin with the severity of skin and skin structure infections – a pilot study

Background: Procalcitonin (PCT) is a specific biomarker for early detection of bacterial infections. While the usefulness of procalcitonin in severe conditions such as sepsis is well established, its relevance in the diagnosis and prognosis of localized cutaneous bacterial infections is unknown. Our aim was to initially evaluate if PCT is a useful parameter for predicting the severity of skin and skin structure infections (SSSI). Furthermore, the correlation of PCT levels with C‐reactive protein (CRP), leukocyte counts, erythrocyte sedimentation rate (ESR), and body temperature was investigated. Patients and Methods: Serum PCT, routine laboratory parameters, and body temperature were regularly examined in 50 consecutive patients with SSSI requiring inpatient intravenous antibiotic treatment. Patients were classified into 2 groups according to the guidelines developed by the FDA (U.S. Food and Drug Administration) as having either an uncomplicated (SSSI) or a complicated skin and skin structure infection (cSSSI). Results: No significant correlation could be detected between the length of inpatient antibiotic treatment and PCT on days 1, 2, 3, and the maximum value on these days. The same result was found when uncomplicated SSSI and complicated SSSI (cSSSI) were evaluated separately. However, PCT levels were significantly higher in the latter. Furthermore, PCT levels showed a significant correlation with CRP, leukocyte count, ESR, and body temperature. Conclusion: PCT might be a useful additional tool for initial diagnosis and monitoring of patients with SSSI.     

Staphylococcus aureus subverts cutaneous defense by d‐alanylation of teichoic acids

The Gram‐positive bacterium Staphylococcus aureus is a frequent skin colonizer that often causes severe skin infections. It has been reported that neutralizing the negatively charged bacterial surface through the incorporation of d ‐alanine in its teichoic acids confers reduced susceptibility of S. aureus towards cationic antimicrobial peptides (AMPs). Using a S. aureus strain deficient in d ‐alanylated teichoic acids (dltA mutant), we demonstrate that d ‐alanylation of its surface reduces the susceptibility of S. aureus to skin‐derived AMPs such as RNase 7 and human beta‐defensins. This is accompanied by a higher killing activity of skin extracts towards the S. aureus dltA mutant as well as towards clinical isolates expressing lower levels of dltA. We conclude that modulation of cell envelope d ‐alanylation may help S. aureus to persist on human skin through evasion of cutaneous innate defense provided by cationic skin‐derived AMPs.     

Staphylococcal scalded skin syndrome in an adult associated with methicillin-resistant Staphylococcus aureus

We report the first adult case of staphylococcal scalded skin syndrome (SSSS) due to methicillin-resistant Staphylococcus aureus (MRSA). This case is particularly unusual as the MRSA produced toxic shock syndrome toxin 1 and enterotoxin, but not exfoliatoxin. SSSS was originally described in neonates and is thought to result from exfoliatins which produce subcorneal splitting of the epidermis and are only produced by certain strains of S. aureus. This case reflects the range of toxins that can be associated with SSSS and the clinical manifestations of MRSA infection in adult patients.     

Skin microbiome and acne vulgaris: Staphylococcus,a new actor in acne

Propionibacterium acnes (P. acnes), the sebaceous gland and follicular keratinocytes are considered the three actors involved in the development of acne. This exploratory study investigated the characteristics of the skin microbiota in subjects with acne and determined microbiota changes after 28 days of application of erythromycin 4% or a dermocosmetic. Skin microbiota were collected under axenic conditions from comedones, papulo‐pustular lesions and non‐lesional skin areas from subjects with mild to moderate acne according to the GEA grading using swabs. Samples were characterized using a high‐throughput sequencing approach that targets a portion of the bacterial 16S rRNA gene. Overall, microbiota samples from 26 subjects showed an overabundance of Proteobacteria and Firmicutes and an under‐representation of Actinobacteria. Staphylococci were more abundant on the surface of comedones, papules and pustules (P=.004 and P=.003 respectively) than on non‐lesional skin. Their proportions increased significantly with acne severity (P<.05 between GEA‐2 and GEA‐3). Propionibacteria represented less than 2% of the bacteria on the skin surface. At Day 28, only the number of Actinobacteria had decreased with erythromycin while the dermocosmetic decreased also the number of Staphylococci. A significant reduction (P<.05) from Day 0 of comedones, papules and pustules with no significant difference between the products was observed. The bacterial diversity on all sampling areas was similar. The dermocosmetic decreased the number of Actinobacteria and Staphylococcus spp. after 28 days. Staphylococcus remained the predominant genus of the superficial skin microbiota. No significant reduction in Staphylococcus spp. was observed with the topical antibiotic.     

小儿葡萄球菌烫伤样皮肤综合征18例临床分析

目的：了解小儿葡萄示菌烫伤样皮肤综合征（SSSS）的临床特点及治疗措施。方法：回顾性分析1994年10月-2001年3月间18例9d-3岁小儿SSSS的临床表现，治疗措施及其疗效。结果：全部均有泛发性红斑及皮肤触痛；除3例无表皮剥脱及尼氏征阴性之外，余者的剥脱面积为5%-69.5%(平均26.8%)。7例作创面分泌物细菌培养，仅1例金黄色葡萄球菌阳性，及时联用新青霉素Ⅱ与头孢菌素，适当的局部处理使裸露创面在7-10d完全愈合，全部痊愈出院。结论：SSSS好发于新生儿及婴幼儿，母乳喂养似对发病无保护作用。早期诊断，及时应用耐β-内酰胺酶抗生素及适当的局部处理是治疗的关键。