Skin findings of Staphylococcus aureus toxin-mediated infection in relation to toxin encoding genes

Biological characterization and genomic analysis of a novel methicillin-resistant Staphylococcus aureus phage, SauPS-28

Staphylococcus aureus, a representative gram-positive bacterium, is a common infectious pathogen widely present in the natural environment. The increasing application of antibiotics is witnessing an increment in the number of clinically resistant strains (such as methicillin-resistant S. aureus [MRSA]), which has posed a great challenge to antimicrobial therapy. In this study, a novel MRSA phage, SauPS-28, was isolated from the lake water of the Guangxi Zhuang Autonomous Region. This phage has an incubation period of approximately 30 min, a lysis period of approximately 40 min, and a burst size of approximately 25 PFU/cell. The isolated phage exhibited good biological stability at a pH range of 6.0-9.0 and temperature range of 4°C-37°C. In addition, the identification of an elongated tail using transmission electron microscopy confirmed that SauPS-28 belongs to the long-tailed phage family. Whole-genome sequencing analysis revealed that SauPS-28 has a 43,286-bp-long genome with 31.03% G + C content. Moreover, SauPS-28 exhibited 95.69% sequence identity with ECel-2020k, while the query coverage was only 66%, which is a newly discovered phage. Whole-genome functional annotation results revealed that SauPS-28 had 68 open reading frames (ORFs). Of these, 30 ORFs are unknown proteins. The results suggest that SauPS-28 could be a lysogenic phage strain. This study thus provides preliminary data to conduct further in-depth analysis of the mechanism of phage-host interaction and provides a reference value for phage therapy.IMPORTANCEIn recent years, drug-resistant bacterial infections have become increasingly serious. As a kind of virus with the ability to infect and lyse drug-resistant bacteria, phage is expected to be a new therapeutic method. In this study, we isolated and purified a new methicillin-resistant Staphylococcus aureus bacteriophage SauPS-28, studied a series of biological characteristics of the bacteriophage, analyzed the genome and structural proteome data of the bacteriophage, and provided reference data for further study of the interaction mechanism between bacteriophage and host bacteria and promoted new antibacterial strategies.

Detection and characterization of potential virulence determinants in Staphylococcus pseudintermedius and S. schleiferi strains isolated from canine otitis externa in Korea

BACKGROUND

A recent increase in the occurrence of canine skin and soft tissue infections, including otitis externa and pyoderma, caused by antimicrobial-resistant Staphylococcus pseudintermedius and S. schleiferi has become a significant public and veterinary health issues.

OBJECTIVE

We investigated the virulence potentials associated with the occurrence of canine otitis externa in S. pseudintermedius and S. schleiferi.

METHODS

In this study, the prevalence of genes encoding leukocidins, exfoliative toxins, and staphylococcal enterotoxins (SEs) was investigated using previously characterized S. pseudintermedius (n = 26) and S. schleiferi (n = 19) isolates derived from canine otitis externa. Susceptibility to cathelicidins (K9CATH and PMAP-36) and hydrogen peroxide (H2O2) was also examined in both staphylococcal species.

RESULTS

A high prevalence of genes encoding leukocidins (lukS/F-I, lukS1/F1-S, and lukS2/F2-S), exfoliative toxins (siet, expB, and sset), and SEs was identified in both S. pseudintermedius and S. schleiferi isolates. Notably, S. pseudintermedius isolates possessed higher number of SE genes, especially newer SE genes, than S. schleiferi isolates harboring egc clusters. Although no significant differences in susceptibility to K9CATH and H2O2 were observed between the two isolate groups, S. pseudintermedius isolates exhibited enhanced resistance to PMAP-36 compared to S. schleiferi isolates.

CONCLUSIONS

These findings suggest that high a prevalence of various toxin genes together with enhanced resistance to cathelicidins may contribute to the pathogenicity of S. pseudintermedius and S. schleiferi in canine cutaneous infections.

The spectrum of staphylococcal scalded skin syndrome: a case series in children

Staphylococcal scalded skin syndrome (SSSS) is a disease caused by certain toxigenic strains of Staphylococcus aureus. While the classic severe phenotype is widely recognized in children, SSSS in fact exists on a spectrum with mild and moderate variants. Misunderstanding the phenotypic spectrum of SSSS may result in misdiagnosis of an otherwise treatable condition. To increase awareness of the heterogeneity of SSSS, we report four cases that together represent a range of clinical presentations.

Staphylococcal scarlet fever associated with staphylococcal enterotoxin M in an elderly patient

Staphylococcal scarlet fever (SSF) is characterized by an exanthem without enanthem, bullae, or exfoliation, and is known to be related to Staphylococcus aureus toxins, especially superantigens. It has been reported in children and young adults. Herein, we report the first case of an elderly patient with SSF caused by staphylococcal enterotoxin M (SEM), associated with otitis externa. The patient presented with maculopapular rashes on both arms, thighs, and abdomen and with erythroderma on the face, ears, neck, chest, and back, all of which was followed by desquamation on the face, ears, and trunk. A culture of ear discharge grew methicillin susceptible S. aureus that was only positive for SEM among the superantigens tested.

Variation in Diagnostic Test Use and Associated Outcomes in Staphylococcal Scalded Skin Syndrome at Children's Hospitals

OBJECTIVES

The incidence of staphylococcal scalded skin syndrome (SSSS) is rising, but current practice variation in diagnostic test use is not well described. Our aim was to describe the variation in diagnostic test use in children hospitalized with SSSS and to determine associations with patient outcomes.

METHODS

We performed a retrospective (2011-2016) cohort study of children aged 0 to 18 years from 35 children's hospitals in the Pediatric Health Information System database. Tests included blood culture, complete blood count, erythrocyte sedimentation rate, C-reactive protein level, serum chemistries, and group A streptococcal testing. K-means clustering was used to stratify hospitals into groups of high (cluster 1) and low (cluster 2) test use. Associations between clusters and patient outcomes (length of stay, cost, readmissions, and emergency department revisits) were assessed with generalized linear mixed-effects modeling.

RESULTS

We included 1259 hospitalized children with SSSS; 84% were ≤4 years old. Substantial interhospital variation was seen in diagnostic testing. Blood culture was the most commonly obtained test (range 62%-100%), with the most variation seen in inflammatory markers (14%-100%). Between hospital clusters 1 and 2, respectively, there was no significant difference in adjusted length of stay (2.6 vs 2.5 days; P = .235), cost ($4752 vs $4453; P = .591), same-cause 7-day readmission rate (0.8% vs 0.4%; P = .349), or emergency department revisit rates (0.1% vs 0.6%; P = .148).

CONCLUSIONS

For children hospitalized with SSSS, lower use of diagnostic tests was not associated with changes in outcomes. Hospitals with high diagnostic test use may be able to reduce testing without adversely affecting patient outcomes.

Mild forms of toxic shock syndrome toxin-1-mediated exanthematous disease related to Staphylococcus aureus infection

The present report describes three patients with toxic shock syndrome toxin (TSST)-1-associated exanthematous disease. In all patients, fever and systemic erythema without hemodynamic disturbance occurred following cellulitis of the lower limbs. At the site of infection, TSST-1 producing Methicillin-susceptible Staphylococcus aureus was detected. They defervesced and erythema resolved in response to administration of an antimicrobial drug, thereby avoiding severe illness. These patients did not meet the criteria for a clinical diagnosis of toxic shock syndrome. Measurement of T-cell receptor Vβ2-positive T cells in the peripheral blood early after onset of symptoms was useful for diagnosis.

What's new with common, uncommon and rare rashes in childhood

PURPOSE OF REVIEW

Children with rashes account for many of the outpatient visits to a general pediatrician. As such, pediatricians are often the first to identify and treat these rashes. Establishing an approach to common, uncommon and rare pediatric rashes assists in accurate assessment. This review highlights newly identified clinical patterns and disease severity.

RECENT FINDINGS

Group A β-hemolytic streptococci (GABHS) have been shown to be an important cause of intertrigo and to cause more widespread disease in some instances. Superficial skin infections with GABHS have been associated with strains secreting exfoliating toxins, whereas deeper infections have been associated with superantigen toxins. Hand-foot-and-mouth disease (HFMD) outbreaks have occurred with more virulent strains, causing more widespread disease that may be confused with eczema herpeticum or varicella. Mycoplasma pneumoniae has been shown to be an important cause of common disorders such as urticaria, and less common disorders such as Stevens-Johnson syndrome and Mycoplasma-associated mucositis. Recurrent toxin-mediated erythema is a recently described entity that must be differentiated from Kawasaki disease.

SUMMARY

The number of rashes acquired in childhood is vast, requiring the pediatrician to be able to identify worrisome rashes from those with a more benign course. Key clinical signs may assist in clinical diagnosis and treatment.

Special problems in burns

Burn units provide a unique set of resources to patients with complex wounds, sepsis, and organ failures. This resource set is useful in a number of traumatic, infectious, and medical conditions as well. Further, many burn patients have sustained simultaneous non-burn trauma which will be managed in burn programs.

Staphylococcal scalded skin syndrome: diagnosis and management in children and adults

Staphylococcal scalded skin syndrome is a potentially life-threatening disorder caused most often by a phage group II Staphylococcus aureus infection. Staphylococcal scalded skin syndrome is more common in newborns than in adults. Staphylococcal scalded skin syndrome tends to appear abruptly with diffuse erythema and fever. The diagnosis can be confirmed by a skin biopsy specimen, which can be expedited by frozen section processing, as staphylococcal scalded skin syndrome should be distinguished from life threatening toxic epidermal necrolysis. Histologically, the superficial epidermis is detached, the separation level being at the granular layer. The diffuse skin loss is due to a circulating bacterial exotoxin. The aetiological exfoliating toxin is a serine protease that splits only desmoglein 1. The exfoliative toxins are spread haematogenously from a localized source of infection, causing widespread epidermal damage at distant sites. Sepsis and pneumonia are the most feared complications. The purpose of this review is to summarize advances in understanding of this serious disorder and provide therapeutic options for both paediatric and adult patients. Recent epidemiological studies have demonstrated that paediatric patients have an increased incidence of Staphylococcal scalded skin syndrome during the summer and autumn. Mortality is less than 10% in children, but is between 40% and 63% in adults, despite antibacterial therapy. Previously, intravenous immunoglobulin had been recommended to combat Staphylococcal scalded skin syndrome, but a recent study associates its use with prolonged hospitalization.