Staphylococcal scalded skin syndrome in two immunocompetent adults caused by exfoliatin B-producing Staphylococcus aureus

Antibiotic Susceptibility Profiling of Human Pathogenic Staphylococcus aureus Strains Using Whole Genome Sequencing and Genome-Scale Annotation Approaches

Staphylococcus species are major pathogens with increasing importance due to the rise in antibiotic resistance. Whole genome sequencing and genome-scale annotation are promising approaches to study the pathogenicity and dissemination of virulence factors in nosocomial methicillin-resistant and multidrug-resistant bacteria in intensive care units. Draft genome sequences of eight clinical S. aureus strains were assembled and annotated for the prediction of antimicrobial resistance genes, virulence factors, and phylogenetic analysis. Most of the studied S. aureus strains displayed multi-resistance toward the tested drugs, reaching more than seven drugs up to 12 in isolate S22. The mecA gene was detected in three isolates (S14, S21, and S23), mecC was identified in S8 and S9, and blaZ was commonly identified in all isolates except strain S23. Additionally, two complete mobile genomic islands coding for methicillin resistance SCCmec Iva (2B) were identified in strains S21 and S23. Numerous antimicrobial resistance genes (norA, norC, MgrA, tet(45), APH(3')-IIIa, and AAC(6')-APH(2″)) were identified in chromosomes of different strains. Plasmid analysis revealed the presence of blaZ, tetK, and ermC in different plasmid types, located in gene cassettes containing plasmid replicons (rep) and insertion sequences (IS). Additionally, the aminoglycoside-resistant determinants were identified in S1 (APH(3')-IIIa), while AAC(6)-APH(2″) was detected in strains S8 and S14. The trimethoprim (dfrC) resistance gene was detected in S. aureus S21, and the fosfomycin (fosB) resistance gene was detected only in S. aureus S14. We also noted that S. aureus S1 belongs to ST1-t127, which has been reported as one of the most frequent human pathogen types. Additionally, we noted the presence of rare plasmid-mediated mecC-MRSA in some of our isolates.

Cutaneous infectious diseases: Kids are not just little people

The changes in immune response that occur with age play a significant role in disease presentation and patient management. Evolution of the innate and adaptive immune systems throughout life, influenced partly by hormonal changes associated with puberty, plays a role in the differences between pediatric and adult response to disease. We review a series of manifestations of dermatologic infectious diseases spanning bacterial, viral, and fungal origins that can be seen in both pediatric and adult age groups and highlight similarities and differences in presentation and disease course. Therapeutic options are also discussed for these infectious diseases, with particular attention to variations in management between these population subgroups, given differences in pharmacokinetics and side effect profiles.

Staphylococcal Scalded Skin Syndrome in a Healthy Adult

We report a case of staphylococcal scalded skin syndrome (SSSS) in a 65-year-old healthy woman. Fever, purulent conjunctivitis, and exfoliation of the skin in the gluteal region were noted. A scarlatiniform rash was observed on the body, and this erythema was followed by generalized desquamation. Staphylococcus aureus was isolated from her eye discharge, posterior nasopharynx, and the erosive surface of the skin. All the investigated strains produced exfoliative toxin B, but none produced toxic shock toxin-1 (TSST-1) or enterotoxin. The patient was treated with antibiotics and fluid supplementation, resulting in subsidence. This case is thought to have been caused by an abortive form of SSSS or a scarlatiniform variant, which is very rare in healthy adults.

Screening of Staphylococcus aureus nasal strains isolated from medical students for toxin genes

Three hundred twenty-one students (156 students with no clinical exposure and 165 students with clinical exposure) were screened for nasal colonization by Staphylococcus aureus; 20.9% of students were S. aureus nasal carriers, and 40.3% of S. aureus isolates harbored toxin genes. The most prevalent genes were tst (15.0 %) and sec (13.4 %). Isolates with multiple genes were only found among clinical students (p = 0.045). Six of 11 PFGE clones were positive for toxin genes. Methicillin-resistant (MRSA) isolates were only detected in the clinical students (4.5 %). The exposure of students to the hospital environment neither radically increased S. aureus nasal carriage, nor the frequency of clinically important toxin gene presence, but it could have influenced the positive selection of toxigenic MRSA strains.

Exfoliative toxins of Staphylococcus aureus

Staphylococcus aureus is an important pathogen of humans and livestock. It causes a diverse array of diseases, ranging from relatively harmless localized skin infections to life-threatening systemic conditions. Among multiple virulence factors, staphylococci secrete several exotoxins directly associated with particular disease symptoms. These include toxic shock syndrome toxin 1 (TSST-1), enterotoxins, and exfoliative toxins (ETs). The latter are particularly interesting as the sole agents responsible for staphylococcal scalded skin syndrome (SSSS), a disease predominantly affecting infants and characterized by the loss of superficial skin layers, dehydration, and secondary infections. The molecular basis of the clinical symptoms of SSSS is well understood. ETs are serine proteases with high substrate specificity, which selectively recognize and hydrolyze desmosomal proteins in the skin. The fascinating road leading to the discovery of ETs as the agents responsible for SSSS and the characterization of the molecular mechanism of their action, including recent advances in the field, are reviewed in this article.

Prevalence of genes encoding extracellular virulence factors among meticillin-resistant Staphylococcus aureus isolates from the University Hospital, Olomouc, Czech Republic

A rather fast and complicated progression of an infection caused by some strains of Staphylococcus aureus could be associated with the expression and co-action of virulence factor complexes in these strains. This study screened the antibiotic susceptibility and prevalence of virulence markers in isolates of meticillin-resistant S. aureus (MRSA) obtained from patients hospitalized at the University Hospital in Olomouc, Czech Republic. A total of 100 isolates was screened for 13 genes encoding extracellular virulence determinants (tst, pvl, eta, etb, sea, seb, sec, sed, see, seg, seh, sei and sej) and for their distribution in sample types. Eighty-nine isolates were positive for at least one of the genes. Genes for etb, pvl, see and seh were not detected in any of the MRSA isolates. No statistically significant differences in the occurrence of the determinants studied among sample types were found.

Staphylococcal Scalded Skin Syndrome: Criteria for Differential Diagnosis from Lyell's Syndrome. Two Cases in Adult Patients

A review of the relative international literature of the last few years is followed by a description of two cases of staphylococcal scalded skin syndrome in adults. As in both cases the initial diagnosis was that of Lyell's syndrome, the main criteria for the differential diagnosis of the two pathologies are considered in order to permit specific and effective treatment.

Clinical manifestations of staphylococcal scalded-skin syndrome depend on serotypes of exfoliative toxins

We sought a possible correlation between the clinical manifestations of staphylococcal scalded-skin syndrome (SSSS) and the serotype of exfoliative toxins (ET) by PCR screening of the eta and etb genes in Staphylococcus aureus strains isolated from 103 patients with generalized SSSS and 95 patients with bullous impetigo. The eta gene and the etb gene were detected in, respectively, 31 (30%) and 20 (19%) episodes of generalized SSSS and 57 (60%) and 5 (5%) episodes of bullous impetigo. Both genes were detected in 52 (50%) episodes of generalized SSS and 33 (35%) episodes of bullous impetigo. To explain this link between etb and generalized SSSS, we examined the distribution of ETA- and ETB-specific antibodies in the healthy population (n = 175) and found that the anti-ETB antibody titer was lower than the anti-ETA titer. Thus, ETA is associated with bullous impetigo and ETB is associated with generalized SSSS, possibly owing to a lower titer of anti-ETB neutralizing antibodies in the general population.

Treatment of staphylococcal scalded skin syndrome

Humans are a natural reservoir for Staphylococcal aureus. Colonization begins soon after birth and predisposes to infection. S. aureus is one of the most common causes of skin infection, giving rise to folliculitis, furunculosis, carbuncles, ecthyma, impetigo, cellulitis and abscesses. In addition, S. aureus may cause a number of toxin-mediated life-threatening diseases, including staphylococcal scalded skin syndrome (SSSS). Epidermolytic toxins released by certain S. aureus strains cause SSSS by cleaving the epidermal cell adhesion molecule, desmogelin-1, resulting in superficial skin erosion. Recent experiments have revealed similarities in the pathophysiology of SSSS and pemphigus foliaceus, an autoimmune disorder that is characterized by antibodies targeting the same epidermal attachment protein. SSSS typically affects neonates and infants but may also occur in predisposed adults. It is painful and distressing for the patient and parents, although most cases respond to antibiotic treatment. Mortality is low in infants but can be as high as 67% in adults, and is dependent on the extent of skin involvement and the comorbid state. Thus, the management of adults who develop SSSS remains a major therapeutic challenge. The antibody response against the toxins neutralizes their effect and prevents recurrence or limits the effects to the area of infection, which is known as bullous impetigo.

Presence of staphylococcal exfoliative toxin A in sera of patients with atopic dermatitis

BACKGROUND

It has been reported that the toxins that Staphylococcus aureus produces are associated with the exacerbation of atopic dermatitis (AD). It has been shown in many studies that staphylococcal enterotoxin (SE) A and SEB contribute to AD by humoral immunity through IgE production as a superantigen. On the other hand, little attention has been paid to the relationship between AD and exfoliative toxin x (ETx).

OBJECTIVE

We investigated the toxins that are frequently detected from the skin of patients and how these toxins affect AD.

METHODS

S. aureus, isolated from the skin of 100 patients with mild to severe AD, were examined for the producibility of toxins by polymerase chain reaction. Serum samples were obtained from 21 patients with mild and moderate AD. The levels of SEB, ETA, total IgE, specific IgE, and specific IgG in sera were measured by ELISA.

RESULTS

SEB was most frequently detected from S. aureus on the skin of these patients as previously reported. And ETx, to which little attention has been paid so far, was frequently detected next to SEB. Furthermore, ETA was detected from the sera of almost all the AD patients. SEB was not detected at all. Although the level of ETA in the AD group was significantly higher than that of controls, ETA-specific IgE was not detected from their sera. High levels of ETA tended to be detected from infantile patients. Although there were no significant differences in the levels of ETA-IgG between AD and the controls, its prevalence was more than twice as high as the controls in AD.

CONCLUSION

These results suggest that many AD patients were exposed to ETx. We conclude that ETx may contribute to exacerbation of AD, particularly in infants, by a mechanism that is not through specific IgE production, unlike SEB.

Understanding the mechanism of action of the exfoliative toxins of Staphylococcus aureus

The exfoliative toxins of Staphylococcus aureus are responsible for the staphylococcal scalded skin syndrome, a blistering skin disorder that particularly affects infants and young children, as well as adults with underlying disease. Their three-dimensional structure is similar to other glutamate-specific trypsin-like serine proteases with two substrate-binding domains and a serine-histidine-aspartate catalytic triad that forms the active site. However, unlike other serine proteases, the exfoliative toxins possess a highly charged N-terminal alpha-helix and a unique orientation of a critical peptide bond, which blocks the active site of the toxins so that, in their native state, they do not possess any significant enzymatic activity. The target for the toxins has recently been identified as desmoglein-1, a desmosomal glycoprotein which plays an important role in maintaining cell-to-cell adhesion in the superficial epidermis. It is speculated that binding of the N-terminal alpha-helix to desmoglein-1 results in a conformation change that opens the active site of the toxin to cleave the extracellular domain of desmoglein-1 between the third and fourth domains, resulting in disruption of intercellular adhesion and formation of superficial blisters. Elucidating the mechanism of action of the toxins and identifying desmoglein-1 as their specific epidermal substrate has not only given us an insight into the pathogenesis of the staphylococcal scalded skin syndrome, but also provided us with useful information on normal skin physiology and the pathogenesis of other toxin-mediated diseases. It is hoped that this knowledge will lead to development of rapid screening and diagnostic tests, and new antitoxin strategies for the treatment and prevention of the staphylococcal scalded skin syndrome in the near future.

Staphylococcal scalded skin syndrome: diagnosis and management

Staphylococcal scalded skin syndrome (SSSS) is a common disorder that is usually seen in infants and children and rarely seen in adults. SSSS usually presents with a prodrome of sore throat or conjunctivitis. Extremely tender flaccid bullae, which are Nikolsky sign-positive, develop within 48 hours and commonly affect the flexures; occasionally, large areas of the skin may be involved. The bullae enlarge and rupture easily to reveal a moist erythematous base, which gives rise to the scalded appearance. SSSS in adults is a rare disorder, though there are now over 50 documented cases. Usually SSSS occurs in predisposed individuals, but not all adults have an underlying illness. Whereas mortality in childhood SSSS is approximately 4%, the mortality rate in adults is reported to be greater than 60%. SSSS is caused by an infection with a particular strain of Staphylococcus aureus, which leads to blistering of the upper layer of the skin, by the release of a circulating exotoxin. It has recently been demonstrated that the exfoliative exotoxin responsible for SSSS leads to the cleavage of desmoglein 1 complex, an important desmosomal protein. The same toxins that are responsible for causing SSSS also cause bullous impetigo. There appears to be a relationship between the disease extent, the amount of toxin produced and whether the toxin is released locally or systemically. As a result there is likely to be a spectrum of disease and there are likely to be a number of milder cases of adult SSSS that go undiagnosed. Social improvements and hygiene have led to a dramatic fall in the number of cases of SSSS. Treatment is usually straightforward, when there is no coexistent morbidity and the presentation is mild, but can be demanding if the patient is particularly ill. SSSS is still associated with mortality, particularly when it occurs in adults.

Staphylococcal scalded-skin syndrome in an adult due to methicillin-resistant Staphylococcus aureus

We report a case of a 71-year-old man with staphylococcal scalded-skin syndrome (SSSS). The patient, with a chronic history of diabetes mellitus, was admitted to our hospital with lumbago, and a diagnosis of renal-cell carcinoma with bone metastasis was made. In hospital he had sudden onset of high fever and erythema, followed by the formation of flaccid bullae and exfoliation, with a positive Nikolsky sign. Methicillin-resistant Staphylococcus aureus (MRSA), producing exfoliative toxin B, was isolated from blood and bile cultures, and Aeromonas hydrophila was isolated from bile culture. Skin biopsy specimen showed a cleavage of the epidermis at the level of the granular layer. The patient was diagnosed as having SSSS and cholecystitis, and was treated with intravenous antibiotics and percutaneous transhepatic gallbladder drainage, which led to recovery. SSSS in adults is usually associated with immunosuppression. A. hydrophila is recognized as an opportunistic pathogen. SSSS should be considered in the differential diagnosis of immunocompromised adult patients with sudden onset of high fever and erythema.

Recent developments in staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome describes a spectrum of superficial blistering skin disorders caused by the exfoliative toxins of Staphylococcus aureus. In its severe form, the exfoliation can spread to cover the entire body surface area. Two S. aureus exfoliative toxin serotypes affecting humans have been identified, but their purpose and mechanism of action have remained elusive. Based on their interaction with human and mouse epidermis, their three-dimensional structure and site-directed mutagenesis studies, it is speculated that they act as atypical serine proteases, and desmoglein-1 has now been identified as the specific epidermal substrate. Recent studies also suggest that the toxins may have a unique superantigenic activity. Clinically, new rapid diagnostic tests have been developed, including one that is able to detect the toxins directly from serum. With early diagnosis and appropriate management, mortality in children remains low and long-term complications are rare because the lesions are superficial and heal rapidly without scarring. In adults, however, the condition carries a mortality of almost 60% despite aggressive treatment, usually because of serious underlying illness. The recent developments in our understanding of the exfoliative toxins should lead to new and improved diagnostic and therapeutic strategies, including the use of specific antixoxins to prevent exfoliation.

Clinical, microbial, and biochemical aspects of the exfoliative toxins causing staphylococcal scalded-skin syndrome

The exfoliative (epidermolytic) toxins of Staphylococcus aureus are the causative agents of the staphylococcal scalded-skin syndrome (SSSS), a blistering skin disorder that predominantly affects children. Clinical features of SSSS vary along a spectrum, ranging from a few localized blisters to generalized exfoliation covering almost the entire body. The toxins act specifically at the zona granulosa of the epidermis to produce the characteristic exfoliation, although the mechanism by which this is achieved is still poorly understood. Despite the availability of antibiotics, SSSS carries a significant mortality rate, particularly among neonates with secondary complications of epidermal loss and among adults with underlying diseases. The aim of this article is to provide a comprehensive review of the literature spanning more than a century and to cover all aspects of the disease. The epidemiology, clinical features, potential complications, risk factors, susceptibility, diagnosis, differential diagnoses, investigations currently available, treatment options, and preventive measures are all discussed in detail. Recent crystallographic data on the toxins has provided us with a clearer and more defined approach to studying the disease. Understanding their mode of action has important implications in future treatment and prevention of SSSS and other diseases, and knowledge of their specific site of action may provide a useful tool for physiologists, dermatologists, and pharmacologists.

Chronic staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome (SSSS), not previously recorded as a chronic disease, persisted for 2 years in a 50-year-old woman with epilepsy and cerebellar ataxia. Lesions initially suggestive of erythema multiforme and toxic epidermal necrolysis evolved over 2 years into those typical for SSSS, with extensive erosions and subcorneal blisters, showing an epidermal split at the granular cell layer. Exfoliatin A-producing phage I-III Staphylococcus aureus, previously linked only to acute mild adult cases of SSSS, was cultured from purulent discharge in the patient's eyes, ears and open skin lesions. The roles of epilepsy and antiepileptic medications are discussed as possible predisposing factors.

The structure of Staphylococcus aureus epidermolytic toxin A, an atypic serine protease, at 1.7 A resolution

BACKGROUND

Staphylococcal epidermolytic toxins A and B (ETA and ETB) are responsible for the staphylococcal scalded skin syndrome of newborn and young infants; this condition can appear just a few hours after birth. These toxins cause the disorganization and disruption of the region between the stratum spinosum and the stratum granulosum--two of the three cellular layers constituting the epidermis. The physiological substrate of ETA is not known and, consequently, its mode of action in vivo remains an unanswered question. Determination of the structure of ETA and its comparison with other serine proteases may reveal insights into ETA's catalytic mechanism.

RESULTS

The crystal structure of staphylococcal ETA has been determined by multiple isomorphous replacement and refined at 1.7 A resolution with a crystallographic R factor of 0.184. The structure of ETA reveals it to be a new and unique member of the trypsin-like serine protease family. In contrast to other serine protease folds, ETA can be characterized by ETA-specific surface loops, a lack of cysteine bridges, an oxyanion hole which is not preformed, an S1 specific pocket designed for a negatively charged amino acid and an ETA-specific specific N-terminal helix which is shown to be crucial for substrate hydrolysis.

CONCLUSIONS

Despite very low sequence homology between ETA and other trypsin-like serine proteases, the ETA crystal structure, together with biochemical data and site-directed mutagenesis studies, strongly confirms the classification of ETA in the Glu-endopeptidase family. Direct links can be made between the protease architecture of ETA and its biological activity.

Staphylococcal scalded skin syndrome in an immunocompromised adult

Staphylococcal scalded skin syndrome, a generalized exfoliative dermatitis complicating infections by exfoliative toxin-producing strains of Staphylococcus aureus, is rarely observed in adults. In contrast to mortality in infants, mortality in adults is usually high. A case of generalized staphylococcal scalded skin syndrome in an immunocompromised woman is reported. Culture of skin biopsy and pleural fluid yielded identical strains of staphylococcus aureus belonging to phage group II. Exfoliative toxins A and B were detected in both isolates. As far as can be determined, this is the first reported case of generalized staphylococcal scalded skin syndrome in an adult with detection of exfoliate toxins A and B in which the patient was treated successfully.

The epidermolytic (exfoliative) toxins of Staphylococcus aureus

Two epidermolytic toxins, produced by different strains of Staphylococcus aureus, split human skin at a site in the upper epidermis. Clinical effects are most common in infants, but adults are susceptible. Epidermolysis may also be observed in the mouse, in vivo and in vitro, and in a few other mammals. Recent in vitro experiments have demonstrated an inhibition by chelators and point to metal-ion, possibly Ca2+, involvement. The epidermolysis effect is insensitive to a wide range of other metabolic inhibitors. The toxin amino acid sequences are similar to that of staphylococcal proteinase, and new experiments by chemical modification and site-directed mutagenesis have shown that toxicity depends on 'active serine' residues of a catalytic triad similar to that found in serine proteases. Furthermore the toxins possess esterolytic activity, also dependent on the 'active serine' sites. However, the toxins have low or undetectable activity towards a range of peptide or protein substrates. In histological and related studies, the toxins bound selectively to an intracellular skin protein, profilaggrin, but there was no evidence that the toxin can enter intact epidermal cells. Therefore, although the circumstantial evidence that the toxins act by proteolysis is convincing, a specific skin proteolytic substrate for the toxin has not been identified.

Staphylococcal scalded skin syndrome in an adult. Influence of immune and renal factors

We report a case of staphylococcal scalded skin syndrome in a 77-year-old man with an infected surgical wound. The patient was immunocompetent and had only mildly impaired renal function. The pathogenic and aetiological factors of the condition are discussed.

Staphylococcal scalded skin syndrome in adults. A clinical review illustrated with a new case

Staphylococcal scalded skin syndrome is rarely observed in adults; only 32 cases have been reported. In contrast to infant cases, the mortality rate is high. Two major risk factors have been identified: kidney failure and immunosuppression. In adults, clinical features are similar to those of the typical pediatric disease, but blood cultures are often positive for Staphylococcus aureus. Detection of the exfoliative toxin is required for diagnosis; the newborn mouse bioassay is, therefore, usually performed. New immunologic methods allow precise characterization of the toxins and oligonucleotide probes can be used for rapid detection of toxigenic strains. We report a case of staphylococcal scalded skin syndrome in an immunocompetent adult in whom blood cultures were positive; this is the first case in which both exfoliative toxins A and B have been identified in an adult.

A double outbreak of exfoliative toxin-producing strains of Staphylococcus aureus in a maternity unit

This report describes a double outbreak of staphylococcal scalded skin syndrome (SSSS) in which two distinct tetracycline-resistant strains of Staphylococcus aureus producing different exfoliative toxins were involved. In the first phase the daytime staff of the delivery unit and eczematous skin conditions in midwives were implicated as the probable source. In the second phase a source within a post-natal ward was suggested with local cross-infection. In the final phase both sources were epidemiologically linked to cases of SSSS. Because early discharge was the policy of the unit many cases presented in the community rather than in the hospital. Confirmation of epidemiological findings was provided by additional laboratory studies. Two distinct strains of S. aureus could be defined, differing in phage-typing patterns, the exfoliative toxin produced, plasmid profile, cadmium resistance and bacteriocin production. Strict care in hand washing with a chlorhexidine-containing detergent was an important control measure.

Staphylococcal scalded skin syndrome (SSSS) and consecutive septicaemia in a preterm infant

Staphylococcal scaled-skin syndrome (SSSS) is a toxin-related epidermolytic disease that usually affects infants and children under 5 years. We report herein a case of a premature infant who had developed SSSS after an infection of the pharynx with staphylococci and who died of septicaemia due to pseudomonas aeruginosa. The primary mechanism of action of epidermolysin still remains unknown. We demonstrate that acantholysis is due to an early edema of the intercellular space with separation of ultrastructurally unaltered desmosomes.

Functional evidence that the Ser-195 residue of staphylococcal exfoliative toxin A is essential for biological activity

The substitution of the serine 195 residue of staphylococcal exfoliative toxin A by a cysteine residue led to a biologically inactive protein. This result is consistent with the hypothesis that exfoliative toxin A could be a protease or a lipase. However, no protease or lipase activity was detected with the native toxin.