Epidemiological features and control of an outbreak of scarlet fever in a Perth primary school

Scarlet fever was associated with feared outbreaks and mortality in the 19th Century. It occurs sporadically in modern society and infection is readily treated with antibiotics. We report on a scarlet fever outbreak in children attending a primary school in Perth, Western Australia, in late 2003. A total of 13 cases were identified over a five week period. Six of the cases were pre-primary children (ages 4 to 5) from the same class of 26 children (attack rate 23.1%). Three of the remaining seven cases were older siblings of pre-primary cases who developed scarlet fever after their younger siblings. Screening of the children and teachers from the two pre-primary classes at the school yielded 12 positive pharyngeal swabs for group A Streptococcus. Emm-typing of the screening isolates indicated that a common strain was circulating within the outbreak pre-primary class, with four of six isolates identified as emm-type 3. The overall group A Streptococcus carriage rate in screened students in this class was 31.6 per cent and the carriage rate for emm-type 3 was 21.1 per cent. Carriers were treated with oral penicillin V to eradicate carriage and control the outbreak. No further cases of scarlet fever were reported after the treatment of pharyngeal carriers. Outbreaks of scarlet fever still occur in young children and identification and treatment of carriers may still be valuable.

Epidemiology and molecular characterization of Streptococcus pyogenes recovered from scarlet fever patients in central Taiwan from 1996 to 1999

One hundred seventy-nine Streptococcus pyogenes isolates recovered from scarlet fever patients from 1996 to 1999 in central Taiwan were characterized by emm, Vir, and pulsed-field gel electrophoresis (PFGE) typing methods. The protocols for Vir and PFGE typing were standardized. A database of the DNA fingerprints for the isolates was established. Nine emm or emm-like genes, 19 Vir patterns, and 26 SmaI PFGE patterns were detected among the isolates. Among the three typing methods, PFGE was the most discriminatory. However, it could not completely replace Vir typing because some isolates with identical PFGE patterns could be further differentiated into several Vir patterns. The prevalent emm types were emm4 (n = 81 isolates [45%]), emm12 (n = 64 [36%]), emm1 (n = 14 [8%]), and emm22 (n = 13 [7%]). Some emm type isolates could be further differentiated into several emm-Vir-PFGE genotypes; however, only one genotype in each emm group was usually predominant. DNA from nine isolates was resistant to SmaI digestion. Further PFGE analysis with SgrAI showed that the SmaI digestion-resistant strains could be derived from indigenous strains by horizontal transfer of exogenous genetic material. The emergence of the new strains could have resulted in an increase in scarlet fever cases in central Taiwan since 2000. The emm sequences, Vir, and PFGE pattern database will serve as a basis for information for the long-term evolutionary study of local S. pyogenes strains.

Enterotoxin B Is the Predominant Toxin Involved in Staphylococcal Scarlet Fever in Taiwan

This study retrospectively reviewed all pediatric cases of staphylococcal scarlet fever (SSF) that occurred during a 10-year period in a 1400-bed tertiary medical center in northern Taiwan. All 20 cases of SSF occurred in previously healthy individuals. Skin and soft-tissue infections predominated among children from whom Staphylococcus aureus was isolated. Polymerase chain reaction testing was used to detect known staphylococcal toxin genes, and of the isolates studied, most (18 [90%] of 20) contained only the staphylococcal enterotoxin B. One of the other strains was positive for staphylococcal enterotoxin A only, and the last strain was positive for both staphylococcal enterotoxin G and staphylococcal enterotoxin I. Pulsed-field gel electrophoresis identified a small cluster of isolates (6 [30%] of 20) that were genetically related, but these strains came from epidemiologically unrelated patients during a 3-year period.

[Epidemiologic aspects of group A betahemolytic streptococcus infections in Galaţi County between 1990 and 2000]

The infections caused by group A betahemolytic streptococcus represent a major problem of community health, worldwide and in Romania, too. Between 1990-2000, in the Galati County, scarlet fever registered values of morbidity with a yearly variability between 8.2 and 54.1 cases/100,000 inhabitants. Angina, although underrated, reached values of 30-80%ooo, followed by erysipelas with an incidence of 80-100%ooo. The socio-economical impact was partially highlighted by assessing the dynamics of hospitalizations which registered values from 363.86 to 527.14%ooo inhabitants. To the previous, the costs of bacteriological investigations were added. For example, 60-80% of cases of angina were positive.

Molecular analysis of group A streptococcal isolates associated with scarlet fever in southern Taiwan between 1993 and 2002

Collected between 1993 and 2002 at a Taiwanese university hospital, 77 group A streptococcus isolates associated with scarlet fever were grouped by emm typing and pulsed-field gel electrophoresis. The predominance of an emm1 clone before 1996 and the presence of genetically diverse emm1 and emm4 strains thereafter were found.

[Present-day Clinical characteristics of scarlatina]

AIM

To study present-day clinical manifestations of scarlatina.

MATERIAL AND METHODS

The authors have reviewed 138 case histories of children with scarlatina treated outpatiently and 51 case histories of hospitalized scarlatina children as well as social and age characteristics of 1657 children and 108 adults hospitalized in the infectious hospital N 1 in 1962-2001. Official data on scarlatina morbidity in Moscow and Russia for 1991-2001 are presented. Antibiotic sensitivity of 414 cultures of group A streptococci (GAS) isolated in 1987-1995 and 1996-2001 was investigated.

RESULTS

Overall and seasonal scarlatina morbidities in 7-14-year-olds appeared to rise significantly. In the majority of cases scarlatina took a mild course but in the adults clinical picture of the disease was rather severe. GAS demonstrated high sensitivity (about 100%) to betalactamic antibiotics. The percentage of erythromycin-resistant streptococcal cultures increased more than 9-fold and reached 1.9% (1996-2001). There is a marked trend to a proportional increase of GAS cultures resistant to tetracycline and gentamycin.

CONCLUSION

Recently, changes have occurred in scarlatina epidemiological and clinical features. Different sensitivity of GAS to antibiotics must be taken into consideration for prescription of etiotropic treatment and prevention of scarlatina at jobs.

Major outbreak of toxic shock-like syndrome caused by Streptococcus mitis

Severe illness caused by viridans streptococci rarely occurs in immunocompetent hosts. Between December 1990 and May 1991, thousands of patients in the YangZi River Delta area of Jiangsu Province, China, suffered from scarlet fever-like pharyngitis. Fewer cases occurred in subsequent years with the same seasonality. Approximately half of the cases developed complications characteristic of streptococcal toxic shock-like syndrome (TSLS). Throat cultures yielded predominant growth of alpha-hemolytic streptococci. All cases admitted to Haian People's Hospital were investigated. Clinical specimens were collected, medical records were reviewed, and bacterial isolates were identified phenotypically and analyzed by 16S rRNA gene sequencing and pulsed-field gel electrophoresis (PFGE). Proteins were purified from culture supernatants by extraction, ammonium sulfate precipitation, and fast-protein liquid chromatography. Biological activities of protein components were determined by subcutaneous inoculation into rabbits. A total of 178 cases of non-beta-hemolytic streptococcal scarlet fever-like pharyngitis were studied. In 88 (79.3%) of 111 patients, oropharyngeal swab cultures grew morphologically identical alpha-hemolytic streptococci. A protein in culture supernatants was pyrogenic in rabbits, was mitogenic for splenocytes, and enhanced rabbit susceptibility to endotoxin challenge. The N-terminal amino acid sequence of this 34-kDa protein showed no homology with known Streptococcus pyrogenic exotoxins. The organism was identified as Streptococcus mitis based on biochemical and 16S rRNA sequence analyses. Representative outbreak isolates from 1990 to 1995 displayed identical PFGE patterns. This TSLS outbreak in southeastern China was caused by a toxigenic clone of S. mitis. An apparently novel toxin may explain the unusual virulence of this organism.

[Antimicrobial sensitivity and characterization of Streptococcus pyogenes strains isoleated from a scarlatina outbreak]

OBJECTIVE

To evaluate the in vitro activities of 13 antimicrobial agents against 47 group A Streptococcus pyogenes (GAS) strains, and to determine the presence of genes encoding streptococcal pyrogenic exotoxin A (SpeA) and the M-protein serotypes.

MATERIALS AND METHODS

A cross-sectional study was conducted at Centro de Salud Dr. José Castro Villagrana, during a scarlet fever outbreak occurring between December 1999 and January 2000, among 137 children at Colegio Espíritu de América. Minimum Inhibitory Concentrations (MICs) were obtained by the semiautomated microdilution method. Automated DNA sequencing was used for analysis of sequence variation in genes encoding the M protein, and SpeA.

RESULTS

All strains were sensitive to betalactams and clindamycin. Six (12.7%) were resistant to erythromycin. The M2 type was the most frequently isolated GAS (27); almost all (96%) bacteria with the SpeA gene had the gene encoding the M2 protein.

CONCLUSIONS

The recent resurgence of GAS infections calls for molecular epidemiology research and studies on the sensitivity to macrolides and beta-lactams.

Molecular characterization of group A Streptococcus strains isolated during a scarlet fever outbreak

Forty group A streptococcus (GAS) isolates, recovered during a scarlet fever outbreak, were grouped based on their DdeI restriction profiles from emm amplicons. Twenty-seven isolates were identified by sequencing as emm2. The emm2 isolates showed the speA1, speB1, and speC1 alleles. Isolation of this GAS type from scarlet fever outbreaks is uncommon.

Outbreak of scarlet fever caused by an erythromycin-resistant Streptococcus pyogenes emm22 genotype strain in a day-care center

We report an outbreak of scarlet fever and pharyngeal colonization with Streptococcus pyogenes in a day-care center in Mexico City. The outbreak strain was resistant to erythromycin but susceptible to clindamycin. T-type 11,12 serotype was found in eight isolates, from two patients and six carriers, which had the emm22 gene. The recognition of streptococci resistant to macrolides causing outbreaks has implications for infection control and for improving antibiotic prescribing patterns in the day-care setting.

[An outbreak of scarlet fever, impetigo and pharyngitis caused by the same Streptococcus pyogenes type T4M4 in a primary school]

EPIDEMIC: Following the notification of an unusual number of scarlet fever cases within the same primary school, the epidemiological and clinical features of the outbreak were investigated. Questionnaire information about the cases was collected from parents and general practitioners per telephone. Throat specimens were taken, before and after treatment, for culturing and specific typing of streptococci was performed to determine transmission. Within a period of one month, 21 schoolchildren in a class of 29 pupils, with a mean age of 5 years, presented with symptoms caused by streptococcal infection (attack rate: 72%). Eight had scarlet fever, 5 suffered from impetigo and 8 had pharyngitis. A further 6 children, outside of this class, had complaints of scarlet fever, impetigo or pharyngitis. For 90% (26/29) of the schoolchildren a throat culture was established. Twelve positive cultures of the same strain of beta-haemolytic group A streptococcus, T4M4 exotoxin C gene positive, were found. The advice given was to treat all positive children for 3 days with azithromycin to prevent complications and further spreading of the disease. After two weeks only one child, that had not taken the antibiotics, still had a positive throat culture. No further cases or complications were reported.

DISCUSSION

The pattern of the outbreak was typical of a person-to-person transmission. This was confirmed by typing of the isolates. The results of this study demonstrate the importance of mandatory notification of infectious clusters by institutions, such as schools, as introduced in the new Dutch Infectious Disease Act. On the one hand, the notification gives the municipal health authority the opportunity to analyse source and transmission dynamics and on the other to prevent disease and complications.

Streptococcus mitis septicaemia and hepatitis

The case of an otherwise well 9-y-old boy with fever, papular rash, jaundice and impaired liver function is presented. Streptococcus mitis sensitive to penicillin grew in blood culture. The boy had an excellent outcome. The clinical spectrum of viridans streptococci may be wider than currently anticipated, and Streptococcus mitis may cause septicaemia and hepatitis in immunocompetent individuals.

Comparison of serotyping, ribotyping and pulsed-field gel electrophoresis for distinguishing group A Streptococcus strains isolated in Albania

Conventional serotyping for T antigens, rRNA gene restriction fragment length polymorphism analysis (ribotyping) and pulsed-field gel electrophoresis were compared for distinguishing among group A streptococci isolated in Albania between 1980-1982 and in 1995. A total of twelve serotypes were identified among seventy GAS strains. Ribotyping revealed eight and eleven distinct patterns after digestion with HindIII and PvuII, respectively. Twenty-three strains of serotype T12 were subdivided in 10 ribotypes and 11 strains of T2 serotype were differentiated in 5 ribotypes. By comparison, PFGE generated 37 patterns after SmaI digestion. The index of discrimination, using the Hunter-Gaston formula, was applied to assess the value of these methods for interpretation of the epidemiological data. For serotyping the value of index was 0.85. The ribotyping system revealed an ID of 0.83 when the combination HindIII and PvuII was used. This index reached 0.97 for PFGE. The methods used were useful to subtype the isolates of GAS.

Comparison of pathogenic factors expressed by group A Streptococci isolated from patients with streptococcal toxic shock syndrome and scarlet fever

Streptococcal toxic shock syndrome (STSS) is an illness with high mortality. To obtain clues to understanding the pathogenesis of STSS, we investigated the expression of several pathogenic factors in ten group A streptococcus (GAS) isolates from ten patients with STSS in Japan, in comparison with ten GAS isolates from children with scarlet fever. The ten scarlet fever-derived GAS isolates were equally low in lethality and anti-phagocytic activity in mice and in the production of streptolysin O (SLO), and equally high in production of superantigenic exotoxins (SAGTs) and cysteine proteinase. By comparison, the ten STSS-derived GAS isolates were heterogeneous in the expression of the above pathogenic factors, which ranged from low to high values. Most of the ten STSS-derived isolates were higher in lethality and anti-phagocytic activity and production of SLO, and lower in the production of SAGTs and cysteine proteinase than the ten scarlet fever-derived isolates. The results suggest that the lethality and anti-phagocytic activity examined in mice and SLO may be involved mainly in the development of most of the ten STSS cases.

Involvement of enterotoxins G and I in staphylococcal toxic shock syndrome and staphylococcal scarlet fever

We investigated the involvement of the recently described staphylococcal enterotoxins G and I in toxic shock syndrome. We reexamined Staphylococcus aureus strains isolated from patients with menstrual and nonmenstrual toxic shock syndrome (nine cases) or staphylococcal scarlet fever (three cases). These strains were selected because they produced none of the toxins known to be involved in these syndromes (toxic shock syndrome toxin 1 and enterotoxins A, B, C, and D), enterotoxin E or H, or exfoliative toxin A or B, despite the fact that superantigenic toxins were detected in a CD69-specific flow cytometry assay measuring T-cell activation. Sets of primers specific to the enterotoxin G and I genes (seg and sei, respectively) were designed and used for PCR amplification. All of the strains were positive for seg and sei. Sequence analysis confirmed that the PCR products, corresponded to the target genes. We suggest that staphylococcal enterotoxins G and I may be capable of causing human staphylococcal toxic shock syndrome and staphylococcal scarlet fever.

Outbreak of scarlet fever at a hospital day care centre: analysis of strain relatedness with phenotypic and genotypic characteristics

An outbreak of scarlet fever involving 12 children occurred at a hospital day care centre from February to March 1996. Twenty-five throat isolates of Streptococcus pyogenes (GAS, group A streptococcus) available from 24 children, including 10 children with scarlet fever and 14 asymptomatic carriers, and one asymptomatic staff member were studied for the presence of genes encoding streptococcal pyrogenic exotoxin types A (speA), B (speB), and C (speC) and for protease activity. Antimicrobial susceptibilities using the E-test, cluster analysis by cellular fatty acid composition and random amplified polymorphic DNA (RAPD) patterns by means of arbitrarily-primed polymerase chain reaction (APPCR) of the isolates were performed to investigate the outbreak. Only one isolate from an asymptomatic child possessed the speA gene. All isolates possessed the speB gene and 24 (96%) isolates were positive for the speC gene. There was no difference in protease activity between isolates from children with scarlet fever and from asymptomatic carriers. Thirteen isolates (10 recovered from children with scarlet fever, two from asymptomatic children, and one from the staff member) were considered to be the same strain according to the identical antimicrobial susceptibility profile and RAPD patterns and were also considered to be similar by cluster analysis of fatty acid composition. These findings suggest that the outbreak was caused by a unique clone of GAS. We conclude that RAPD typing and cluster analysis by cellular fatty acids composition both provide a powerful tool for epidemiological investigation of GAS infections.

[Serotype distribution and antimicrobial susceptibility of group A streptococci (Streptococcus pyogenes) isolated in Taiwan]

T-protein serotypes and antimicrobial susceptibility of a total of 139 group A streptococci (GAS) strains isolated in Taiwan area in 1993 and during the outbreak of scarlet fever in 1994 were analyzed. All strains were T-typable, and T12 (42.46%) and T4 (38.85%) were the dominant T types. According to the results of analysis of antimicrobial susceptibility, all GAS strains were divided into 9 resistotypes, A (all susceptible), B (resistant to tetracycline), C (resistant to erythromycin and tetracycline), D (resistant to chloramphenicol and tetracycline), E (resistant to chloramphenicol and clindamycin), F (resistant to chloramphenicol, clindamycin and tetracycline), G (resistant to clindamycin, erythromycin and tetracycline), H (resistant to chloramphenicol, clindamycin, erythromycin and tetracycline), and I (resistant to chloramphenicol, clindamycin, erythromycin, tetracycline and vancomycin). Type B (37.42%) was the dominant type. Type A (25.91%), and type H (26.63%) also appered with high incidence. Most of strains isolated from Mid-Taiwan were type H. Only one strain, that was isolated in I-lan, was resistant to vancomycin, in addition to resistant to chloramphenicol, clindamycin, erythromycin, and tetracycline. All strains were susceptible to penicillin G, ampicillin, and ceftriaxone. Some strains were resistant to chloramphenicol (32.38%), clindamycin (30.22%), erythromycin (31.66%), tetracycline (73.39%), and vancomycin (0.70%). During the outbreak of scarlet fever in 1994, the dominant T types of strains isolated in North-Taiwan and Mid-Taiwan were T4 and T12, respectively, and the major resistotypes of those strains were B and H types, respectively. These clues suggested that the outbreaks occurring in North-Taiwan and Mid-Taiwan may have no epidemiological linkage between each other.