Staphylococcal exanthematous disease in a newborn due to a virulent methicillin-resistant Staphylococcus aureus strain containing the TSST-1 gene in Europe: an alert for neonatologists

Neonatal Toxic Shock Syndrome-like Exanthematous Disease: A Report of Two Cases

Neonatal toxic shock syndrome (TSS)-like exanthematous disease is characterized by exanthema, thrombocytopenia and fever in neonates infected with TSS toxin-1 producing Staphylococcus aureus . Although the disease is rare, it should be known to neonatologists as it represents a differential diagnosis in neonates with exanthema and thrombocytopenia. Two presented neonates with Neonatal TSS-like exanthematous disease are rare European cases of this specific neonatal disease.

Neonatal toxic shock syndrome-like exanthematous disease: A French case series

Neonatal toxic shock syndrome-like exanthematous disease (NTED) was first described in Japan in the 1990s. It results from the secretion of superantigenic toxins by Staphylococcus aureus. Diagnostic criteria include generalized macular erythema and at least one of the following three features: fever (>38°C), thrombocytopenia (<150,000/mm³ ), low positive C reactive protein (10-50 mg/L) in the absence of another known disease process. We herein describe four cases from France, involving both MSSA and "Geraldine" MRSA. This report aims to bring this underdiagnosed disease to the attention of pediatricians and infectious disease specialists, to improve the management of affected newborns.

Neonatal Toxic Shock Syndrome-Like Exanthematous Disease in North America

Neonatal toxic shock syndrome (TSS)-like exanthematous disease (NTED) is a syndrome first reported in Japan. Neonates develop systemic exanthema, thrombocytopenia, and fever usually during the first week of life. The disease is distinguished from frank TSS because affected infants are not severely ill and do not meet TSS criteria. Most infants are confirmed to be colonized with TSST-1 producing strains of S. aureus. Suggested diagnostic criteria for NTED include a skin rash with generalized macular erythema and one of the following symptoms: fever >38.0°C, thrombocytopenia <150 x103uL, or low positive C-reactive protein (1-5 mg/dL) in the absence of another known disease process. NTED is common in Japanese NICUs, but outside Japan, only one case has been reported in France. We describe the first case of NTED reported in North America.

Skin Infections Caused by Staphylococcus aureus

Staphylococcus aureus is the most common pathogen involved in skin infections worldwide, regardless of the patient's age, the climate or geographical area. The main skin clinical manifestations can be linked to a few toxins produced by the bacteria, which give rise to a rich and varied clinical spectrum. Panton Valentine leucocidin, exfoliatins, enterotoxins and toxin shock syndrome toxin 1 are the main toxins involved in most dermatological manifestations associated with S. aureus. Other less frequent cutaneous manifestations can occur in endocarditis, bacteraemia. Currently, the most important event is worldwide emergence of community-acquired S. aureus resistant to methicillin (CA-MRSA), mainly causing skin infections.

Postpartum Methicillin-Resistant Staphylococcus aureus Toxic Shock Syndrome Caused by a Perineal Infection

Although toxic shock syndrome (TSS) is rare, multiorgan failure can occur without early identification and appropriate therapy. In particular, a few cases of postpartum TSS due to methicillin-resistant Staphylococcus aureus (MRSA) have been reported. Here, we describe a rare case in which a 32-year-old Japanese woman had TSS due to MRSA that was caused by a perineal infection after a normal vaginal delivery. Twelve days after giving birth to a healthy child, she was readmitted to our hospital due to a 2-day fever and perineal pain without uterine tenderness. She developed emesis and watery diarrhea on the night of admission. On the second day, a diffuse cutaneous macular rash appeared over her trunk. Laboratory data revealed deteriorated renal function and thrombocytopenia. Her history and clinical results were compatible with a typical course of TSS. Administration of ceftriaxone and clindamycin was started immediately after admission and was effective. The patient recuperated steadily over the next week with desquamation of the skin. MRSA was isolated from her vaginal discharge and was found to produce TSS toxin 1 (TSST-1). Furthermore, since MRSA was not detected in the nasal and vaginal cavity during pregnancy, it suggests that vaginal colonization can also occur postpartum and be the disease source in mothers. Therefore, MRSA infections should be considered when treating for postpartum TSS.

Prospective Surveillance of Community-Onset and Healthcare-Associated Methicillin-ResistantStaphylococcus aureusIsolated from a University-Affiliated Hospital in Japan

We conducted a prospective comparative study of community-onset (CO) and healthcare-associated (HA) methicillin-resistant Staphylococcus aureus(MRSA) strains between 2000 and 2001 at Tokyo Women's Medical University Hospital (1,500 beds) in Japan. Of the 172 consecutive MRSA isolates analyzed, 13 (8%) were categorized as CO-MRSA. The mean age of patients with CO-MRSA was significantly younger than that of patients with HA-MRSA. Most CO-MRSA strains were isolated from skin and more likely to be susceptible to erythromycin, clindamycin, tetracycline, levofloxacin, and spectinomycin compared to HA-MRSA isolates. Pulsed-field gel electrophoresis (PFGE) analysis, staphylococcal cassette chromosome mec(SCCmec) typing, and multi-locus sequence typing (MLST) revealed that CO-MRSA strains were divided into the following multi-clones: 3 clone A: II: ST5 (PFGE type: SCCmec type: MLST sequence type); 1 L: II: ST5; 1 H: IV: ST1; 1 I: IV: ST81; 2 D: IV: ST8; 1 B: IV: ST89; 1 B: IV: ST379; and 3 B: IV: ST91. Of the 159 HAMRSA strains, 124 (78%) belonged to a single clone (PFGE clone A: SCCmec type II: tst and sec positive: coagulase type II: multi-drug resistance). Four CO-MRSA strains belonging to PFGE clone B: SCCmec type IV: MLST clonal complex 509 (ST89, 91, 379) had the exfoliative toxin B (etb) genes, but all CO-MRSA and HA-MRSA strains did not possess the Panton-Valentine leukocidin (pvl) genes. These results demonstrate that multiple lineages of CO-MRSA have the potential for dissemination in the community in Japan.

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.

Change of specific T cells in an emerging neonatal infectious disease induced by a bacterial superantigen

A new epidemic, NTED, has recently occurred in Japan. The cause of NTED is a bacterial superantigen, TSST-1. The aim of the present study was to analyze the change in Vbeta2(+) T cells reactive to TSST-1 in NTED in order to establish T-cell-targeted diagnostic criteria for NTED. Blood samples from 75 patients with clinically diagnosed NTED were collected from 13 neonatal intensive care units throughout Japan. We investigated the percentages of Vbeta2(+), Vbeta3(+) and Vbeta12(+) T cells and their CD45RO expressions in the samples using flow cytometry. In 18 of the 75 patients, we conducted multiple examinations of the T cells and monitored serial changes. The Vbeta2(+) T-cell population rapidly changed over three phases of the disease. Whereas the percentage of Vbeta2(+) T cells was widely distributed over the entire control range, CD45RO expression on Vbeta2(+) T cells in CD4(+) in all 75 patients was consistently higher than the control range. Patients cannot necessarily be diagnosed as having NTED based on expansion of Vbeta2(+) T cells alone in the early acute phase. Instead, CD45RO expression on specific Vbeta2(+) cells is a potential diagnostic marker for a rapid diagnosis of NTED. We present three diagnostic categories of NTED. Fifty patients (66.7%) were included in the category 'definitive NTED'. It is important to demonstrate an increase of Vbeta2(+) T cells in the following phase in cases of 'probable NTED' or 'possible NTED'.

Usefulness of antimicrobial resistance pattern for detecting PVL- or TSST-1-producing meticillin-resistant Staphylococcus aureus in a French university hospital

Several recent reports have suggested that community-associated meticillin-resistant Staphylococcus aureus (MRSA) clones, particularly those harbouring genes for Panton-Valentine leukocidin (PVL) or toxic shock syndrome toxin 1 (TSST-1), are increasingly responsible for infections in hospitals. Here, a retrospective study was carried out to investigate whether antimicrobial resistance patterns could be used to detect these pathogens in a French university hospital. Isolates were characterized by antimicrobial susceptibility testing, PCR profiling (PVL genes and tst), PFGE typing and multilocus sequence typing. Demographic and clinical data were collected from all patients. For PVL-positive MRSA, the typical antimicrobial resistance pattern (susceptible to fluoroquinolones, non-susceptible to fusidic acid, kanamycin resistant and susceptible to gentamicin and tobramycin) had a sensitivity of 77.8 % and a positive predictive value (PPV) of 100 %. For tst-positive MRSA, the antimicrobial resistance pattern (susceptible to fluoroquinolones and non-susceptible to fusidic acid) had a sensitivity of 100 % and a PPV of 72.4 %. These results suggest that phenotypic rules based on antimicrobial resistance patterns are potentially useful for the detection of PVL- and tst-positive MRSA isolates.

Virulence determinants in community and hospital meticillin-resistant Staphylococcus aureus

Staphylococcus aureus produces many virulence factors, most of which act in a synergistic and coordinated fashion. Some appear to be specifically associated with certain severe infections and are produced by meticillin-resistant Staphylococcus aureus (MRSA) clones distributed worldwide. Superantigenic exotoxins appear to be major virulence factors in hospital MRSA clones (HA-MRSA), and staphylococcal enterotoxin A (SEA) may be involved in the physiopathology of septic shock. Panton Valentine Leucocidin (PVL) has emerged as a major virulence factor in community-acquired Staphylococcus aureus (CA-MRSA) infections. In particular, the leukotoxic action of PVL is responsible for the high mortality rate associated with necrotizing pneumonia. CA-MRSA can also harbour the toxic shock toxin 1 (TSST-1) and rarely the exfoliative toxin.

Staphylococcus aureus strains isolated from bloodstream infections changed significantly in 2006

We studied 358 Staphylococcus aureus strains isolated from bloodstream infections (BSI) observed during an epidemiological study covering 2,007,681 days of hospitalization in 32 healthcare institutions (HCIs) between 2004 and 2006. The strains were tested for antibiotic susceptibility and characterized genetically. The incidence of S. aureus BSI declined regularly through 2004 and 2005 and then significantly increased in 2006 (+80%). This was largely due to an increase in BSI involving methicillin-sensitive S. aureus (MSSA) strains and nonmultiresistant methicillin-resistant S. aureus (NORSA) strains. Ninety-six percent of the NORSA strains were resistant only to methicillin and fluoroquinolones. Most of the MSSA strains belonged to a small number of pulsed-field gel electrophoresis (PFGE) divisions and were associated with epidemic phenomena in HCIs. The NORSA strains also clustered into a limited number of PFGE divisions but could not be related to any local outbreak in HCIs. In 2006, there was a significant increase in the incidence of BSI associated with tst gene-positive MSSA strains (+275%) and the first three BSI associated with tst gene-positive MRSA were observed. PFGE data revealed a limited heterogeneity among the tst gene-positive strains without any outbreak in the HCIs. Our study underlines the need for infection control teams to focus efforts on preventing both MRSA and MSSA BSI. As recently demonstrated in vitro, fluoroquinolones may enhance horizontal transfer of virulence and antibiotic resistance genes. These antibiotics are widely used in France, so our findings raise the issue of whether their use has contributed to the acquisition of mecA and tst genes by S. aureus strains.

A severe case of neonatal toxic shock syndrome-like exanthematous disease with superantigen-induced high T cell response

Most newborn patients with a neonatal type of toxic shock syndrome (TSS), called neonatal TSS-like exanthematous disease (NTED), exhibit mild clinical symptoms. We present the case of a patient with NTED who exhibited exceptionally severe clinical symptoms and an adult-type T cell response to the causative toxin TSS toxin-1.

Choc toxique staphylococcique maternofœtal sur chorioamniotite

We report a rare case of mother-infant pair with Staphylococcal Toxic Shock Syndrome (TSS). A term neonate was born by caesarean section for maternal septic syndrome during per-partum. He presented with respiratory distress complicated by pulmonary hypertension, skin rash, and multiple organ system involvement. Staphylococcus aureus was isolated from placenta, surface swabs and gastric aspirate. He received adapted antibiotics, respiratory support by high frequency ventilation and NO. The mother had shock, skin rash and inflammatory syndrome. Outcome was good in both cases. The isolate produced enterotoxin C and L. Shock, exanthematous disease and multi-organ involvement complicating a staphylococcal infection in neonate must lead to suspect a TSS.

Detection of new methicillin-resistant Staphylococcus aureus clones containing the toxic shock syndrome toxin 1 gene responsible for hospital- and community-acquired infections in France

Methicillin-resistant Staphylococcus aureus (MRSA) clones harboring the toxic shock syndrome toxin 1 (tst) gene have been detected in France and in Switzerland since 2002. During a passive survey conducted between 2002 and 2003, we collected 103 tst-positive S. aureus isolates from 42 towns in France, of which 27 were resistant to methicillin. The tst-positive MRSA belonged to two clones: a major clone comprising 25 isolates of sequence type (ST) 5 and agr group 2 and a minor clone comprising two isolates of ST30 and agr3. The tst-positive MRSA clones were associated with both hospital-acquired (12 cases) and community-acquired (8 cases) infections. The MRSA clones were mainly isolated from children (overall median age, 3 years). They caused a variety of clinical syndromes, including toxic shock syndrome and suppurative infections. Both clones were found to harbor a type IV staphylococcal chromosomal cassette mec (SCCmec) and to have similar antibiotic resistance profiles (usually resistant to oxacillin, kanamycin, and tobramycin and with intermediate resistance to fusidic acid). The origin of these clones is unclear. The tst-positive agr2 MRSA clone has the same sequence type (ST5) of two pandemic nosocomial MRSA clones, namely, the Pediatric clone and the New York/Japan clone. These findings suggest that all these clones are phylogenetically related. The pulsotype of the tst-positive MRSA clones differed from that of methicillin-sensitive S. aureus (MSSA) clones by a single band involving the SCCmec element. These findings suggest that the tst-positive MRSA clones may have emerged from their respective MSSA counterparts.

Epidemiology and typing of Staphylococcus aureus strains isolated from bloodstream infections

We carried out an epidemiological study covering 2,365,067 patient days of hospitalization between 2000 and 2003. During this time, 413 Staphylococcus aureus bloodstream infections occurred. This corresponds to 15% of the 2,676 bloodstream infections observed during this period in the 31 hospitals in our region of France, which has 2.5 million inhabitants. The incidence of nosocomial S. aureus bloodstream infections was 0.11 per 1,000 days of hospitalization. The prevalence of methicillin-resistant S. aureus (MRSA) strains, of which 13% were nonmultiresistant MRSA (NORSA), was 33%, and this percentage was stable over the 4 years. In contrast, the prevalence of S. aureus strains susceptible to methicillin but resistant to quinolones or susceptible to methicillin but multiresistant to antibiotics (EMSSA strains) increased from 4% in 2000 to 23% in 2003. As previously reported, MRSA strains were mostly recovered from nosocomial bloodstream infections, whereas NORSA strains-generally considered to be responsible for community-acquired infections-were always isolated from nosocomial bloodstream infections. Pulsed-field gel electrophoresis (PFGE) analysis of 109 MRSA strains and 15 EMSSA strains demonstrated clonal diffusion of the three major French MRSA clones and revealed considerable genetic heterogeneity among EMSSA strains. Although no epidemiologically related NORSA strains clustered in particular PFGE groups, the distribution of MRSA strains isolated from bloodstream infections according to the portal of entry (vascular devices, pulmonary, and urinary) was not random for the major PFGE clones, suggesting that each MRSA lineage displays particular virulence features.

Virulence and antibiotic susceptibility of Staphylococcus aureus strains isolated from various origins

We looked for links between the antibiotic susceptibility pattern of Staphylococcus aureus strains, their source and their virulence genes. Forty-four methicillin-sensitive and -resistant S. aureus strains from four antibiogroups were studied by SmaI macrorestriction and PCR detection of ea, eb, tst, lukS-PV and lukF-PV. Genes encoding virulence factors were most prevalent (i) in S. aureus strains originated from skin, (ii) in methicillin-sensitive, quinolone-resistant strains or in methicillin-sensitive multiresistant strains (EMSSA strains), and (iii) in strains with decreased susceptibility or resistance to fusidic acid. This is consistent with the hypothesis that S. aureus antibiotic resistance promoted by local antibiotic treatment also contributes to the emergence of virulence strains.

Emerging gram-positive bacterial infections

Over the last several decades, a number of previously known or newly described species of gram-positive bacteria have emerged as important human pathogens, particularly in industrialized countries. These microbes have demonstrated an impressive ability to produce an array of striking infectious diseases never before seen or only infrequently encountered in the past. Despite aggressive therapeutic intervention, many of these conditions portend significant morbidity and mortality. Diseases caused by members of the Staphylococcus and Streptococcus genera have figured prominently in this regard, with Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, and other beta-hemolytic streptococci being regarded as the most important species. This review focuses on the clinical and microbiologic aspects of key emerging infections caused by this group of microorganisms.