Invasive group A streptococcal infections in Ontario, Canada. Ontario Group A Streptococcal Study Group

Molecular analysis of the role of streptococcal pyrogenic Exotoxin A (SPEA) in invasive soft-tissue infection resulting from Streptococcus pyogenes

Epidemiological studies strongly implicate the bacterial superantigen, streptococcal pyrogenic exotoxin A (SPEA), in the pathogenesis of necrotizing soft-tissue infection and toxic shock syndrome resulting from Streptococcus pyogenes. SPEA can act as a superantigen and cellular toxin ex vivo, but its role during invasive streptococcal infection is unclear. We have disrupted the wild-type spea gene in an M1 streptococcal isolate. Supernatants from toxin-negative mutant bacteria demonstrated a 50% reduction in pro-mitogenic activity in HLA DQ-positive murine splenocyte culture, and up to 20% reduction in activity in human PBMC culture. Mutant and wild-type bacteria were then compared in mouse models of bacteraemia and streptococcal muscle infection. Disruption of spea was not associated with attenuation of virulence in either model. Indeed, a paradoxical increase in mutant strain-induced mortality was seen after intravenous infection. Intramuscular infection with the SPEA-negative mutant led to increased bacteraemia at 24 h and a reduction in neutrophils at the site of primary muscle infection. Purified SPEA led to a dose-dependent increase in peritoneal neutrophils 6 h after administration. SPEA is not a critical virulence factor in invasive soft-tissue infection or bacteraemia caused by S. pyogenes, and it could have a protective role in murine immunity to pyogenic infection. The role of this toxin may be different in hosts with augmented superantigen responsiveness.

Evaluation of the Strep A OIA assay versus culture methods: ability to detect different quantities of group A Streptococcus

The Strep A OIA assay by Biostar (Boulder, Co., USA) is a unique optical immunoassay system for the rapid detection of Group A streptococcal carbohydrate. As part of a community-based pediatric cohort study of Group A Streptococcus (GAS) persistence following antibiotic therapy of pharyngitis, the performance of the Strep A OIA assay was compared with the amount of growth from standard throat swab culture methods. A total of 363 throat swabs taken over the course of the study was evaluated from 248 children between 2 and 18 years of age. Two culture methods were performed: an agar plate with the throat swab using Columbia agar base with 5% sheep blood incubated under an anaerobic environment for 48 h and Todd-Hewitt broth (THB) enhancement. The Strep A OIA was then performed. A total of 144 of 363 (39.7%) samples was positive for GAS by one or more of the laboratory tests across study visits: agar culture detected 132 of 144 (91.7%), THB culture detected 128 of 144 (88.9%), and the Strep A OIA assay detected 129 of 144 (89.6%). Complete agreement among all three laboratory tests was found for 333 of 363 (91.7%) of the samples. Agar culture results were comparable to THB cultures with a sensitivity of 96.9%, specificity of 96.6%, a positive predictive value of 93.9%, and a negative predictive value of 98.3%. Although the performance of the Strep A OIA assay had similar specificity (96.5%) and positive predictive value (93.8%) compared with the combined results of the two culture methods, the sensitivity (89.0%) and negative predictive value (93.6%) were lower. A significant difference (p < 0.001) was found in the ability of the Strep A OIA assay to detect agar culture-positive swabs that had a light growth (1+ or 2+) (63.0%) versus a moderate (3+) or heavy (4+) growth (98.1%) of GAS. Although the Strep A OIA assay allows GAS throat swab results to be reported an average of 24 h sooner than either of the cultures, the rapid assay was not as sensitive in detecting light growth GAS-positive cultures.

Febrile lady with acute renal failure and desquamating erythema

A 63-year-old woman developed acute renal failure and streptococcal toxic shock syndrome caused by streptococcus group G. Initially, an erythema resembling vasculitis was misleading. The subsequent clinical course, however, was typical for streptococcal toxic shock syndrome and met the criteria put forward by The Working Group on Severe Streptococcal Infections. In patients infected with streptococcus group G, toxic shock syndrome is rare. The streptococcus group G strains isolated from this patient did not produce pyrogenic exotoxins. Instead they produced an M-like protein related to group C and G streptococci that do not act as superantigens.

[Gastrointestinal complications of diabetes mellitus]

BACKGROUND

Diabetes mellitus leads to a broad spectrum of symptoms and manifestations in the field of gastroenterology.

BASIS

This article reviews the pathophysiology, differential diagnoses and secondary diseases of the gastrointestinal tract in diabetic patients.

CLINICAL APPEARANCE

Motility disorders, infectious complications, secondary diseases of the stomach, liver, pancreas, gall bladder, small and large bowel are considered and discussed. Diagnostic and therapeutic approaches for the management of diabetic enteropathy are presented.

CONCLUSION

The new strategies in diagnosis and therapy for a successful prevention or treatment of gastrointestinal complications due to diabetes mellitus need good cooperation of clinical specialties.

High-resolution genotyping of Streptococcus pyogenes serotype M1 isolates by fluorescent amplified-fragment length polymorphism analysis

We have used fluorescent amplified-fragment length polymorphism (FAFLP) analysis to subtype clinical isolates of Streptococcus pyogenes serotype M1. Established typing methods define most M1 isolates as members of a clone that has a worldwide distribution and that is strongly associated with invasive diseases. FAFLP analysis simultaneously sampled 90 to 120 loci throughout the M1 genome. Its discriminatory power, precision, and reproducibility were compared with those of other molecular typing methods. Irrespective of disease symptomatology or geographic origin, the majority of the clinical M1 isolates shared a single ribotype, pulsed-field gel electrophoresis macrorestriction profile, and emm1 gene sequence. Nonetheless, among these isolates, FAFLP analysis could differentiate 17 distinct profiles, including seven multi-isolate groups. The FAFLP profiles of M1 isolates reproducibly exhibited between 1 and more than 20 amplified fragment differences. The high discriminatory power of genotyping by FAFLP analysis revealed genetic microheterogeneity and differentiated otherwise "identical" M1 isolates as members of a clone complex.

A Streptococcus pyogenes outbreak caused by an unusual serotype of low virulence: the value of typing techniques in outbreak investigations

OBJECTIVES

To investigate and stop the spread of an outbreak of Streptococcus pyogenes infection in a district general hospital, involving 19 patients and two nurses over a 20-day period.

METHODS

All suspected persons were investigated using conventional bacteriological techniques, followed by M, T and exotoxin gene-typing of the isolates in a national reference laboratory.

RESULTS

11 patients and both nurses were associated with the acute surgical ward on one floor of the hospital. They were infected with serotype M 9/T B3264, a strain with apparently low virulence, which has not been previously associated with outbreaks. Two other patients on the same floor each had different types and there were two clusters of another S. pyogenes serotype on other floors, each involving two patients. Two (unrelated) patients yielded other types of S. pyogenes. The patients were not seriously ill but had some delay in wound healing.

CONCLUSIONS

The value of typing the isolates of S. pyogenes in this outbreak was in defining which patients were involved. No added value could be ascribed to the exotoxin gene-typing results.

Risk factors in the pathogenesis of invasive group A streptococcal infections: role of protective humoral immunity

An impressive change in the epidemiology and severity of invasive group A streptococcal infections occurred in the 1980s, and the incidence of streptococcal toxic shock syndrome cases continues to rise. The reason for the resurgence of severe invasive cases remains a mystery-has there been a change in the pathogen or in host protective immunity? To address these questions, we have studied 33 patients with invasive infection caused by genotypically indistinguishable M1T1 strains of Streptococcus pyogenes who had different disease outcomes. Patients were classified as having severe (n = 21) and nonsevere (n = 12) invasive infections based on the presence or absence of shock and organ failure. Levels of anti-M1 bactericidal antibodies and of anti-streptococcal superantigen neutralizing antibodies in plasma were significantly lower in both groups than in age- and geographically matched healthy controls (P < 0.01). Importantly, the levels of these protective antibodies in plasma samples from severe and nonsevere invasive cases were not different. Together the data suggest that low levels of protective antibodies may contribute to host susceptibility to invasive streptococcal infection but do not modulate disease outcome. Other immunogenetic factors that regulate superantigen responses may influence the severity of systemic manifestations associated with invasive streptococcal infection.

Emergence and spread of a new clone of M type 1 group A Streptococcus coincident with the increase in invasive diseases in Japan

BACKGROUND

In Japan invasive group A streptococcal infections such as sepsis and toxic shock syndrome (TSS) have increased since 1992. As is the case in the United States and Europe, M1 serotype is predominant among the isolates from Japanese patients.

METHODS

By restriction enzyme digestion and pulsed field gel electrophoresis, we investigated the whole genomic DNA profiles of 95 M type 1 group A streptococcal strains isolated from patients with serious diseases including sepsis, toxic shock syndrome, necrotizing fasciitis and nonsuppurative complications and with uncomplicated pharyngitis during 1979 through 1996 in Japan.

RESULTS

The genome profiles among 8 of 10 isolates from patients with serious diseases in 1979 through 1991 were all the same and were shared by the profiles of the 35 of 48 isolates from patients with uncomplicated pharyngitis in 1982 through 1991. All 18 strains isolated from patients with invasive diseases in 1992 to 1996 had a unique profile, which was shared by the profiles of 18 of 19 isolates from uncomplicated pharyngitis during the same period. This genomic profile was distinct from the predominant or any other profiles before 1992, and it was found to be a new clone.

CONCLUSIONS

The emergence and spread of this new clone of M type 1 Streptococcus after 1991 may be associated with the increase in invasive streptococcal infections that occurred during the same period in Japan. Genomic profiles as well as serotypes of streptococcal isolates are important for the epidemiology of clinical relevance in streptococcal diseases.

Fatal group A Streptococcal toxic shock-like syndrome in a child with varicella: report of the first well documented case with detection of the genetic sequences that code for exotoxins spe A and B, in São Paulo, Brazil

A previously healthy seven-year-old boy was admitted to the intensive care unit because of toxaemia associated with varicella. He rapidly developed shock and multisystem organ failure associated with the appearance of a deep-seated soft tissue infection and, despite aggressive treatment, died on hospital day 4. An M-non-typable, spe A and spe B positive Group A Streptococcus was cultured from a deep soft tissue aspirate. The criteria for defining Streptococcal toxic shock-like syndrome were fulfilled. The authors discuss the clinical and pathophysiological aspects of this disease as well as some unusual clinical findings related to this case.

Multivalent group A streptococcal vaccine designed to optimize the immunogenicity of six tandem M protein fragments

One of the major challenges in the development of group A streptococcal M protein-based vaccines is the multiplicity of M types expressed by these organisms. Previous studies have shown that multivalent vaccines containing as many as eight M protein fragments in tandem were immunogenic and evoked opsonic antibodies. It was also noted that the C-terminal fragments of these hybrid proteins were often not immunogenic or evoked only low levels of opsonic antibodies, suggesting that the C-terminus of the molecule may have been preferentially degraded or altered in vivo. In the present studies, we designed a hexavalent vaccine containing protective M protein peptides from types 24, 5, 6, 19, 1, and 3 group A streptococci. In order to "protect" the carboxy-terminal components, the amino-terminal M24 fragment was reiterated on the carboxy-terminal end of the construct. The hexavalent vaccine was immunogenic in laboratory animals and evoked high titers of antibodies against each of the native M proteins represented in the vaccine and bactericidal antibodies against all six sterotypes of group A streptococci. The vaccine was equally immunogenic when delivered in alum or in complete Freund's adjuvant. None of the immune sera contained antibodies that crossreacted with human heart tissue. Our results show that complex multivalent group A streptococcal vaccines can be designed in such a way that each M protein fragment is immunogenic and evokes protective antibodies.

Rapid molecular genetic subtyping of serotype M1 group A Streptococcus strains

Serotype M1 group A Streptococcus, the most common cause of invasive disease in many case series, generally have resisted extensive molecular subtyping by standard techniques (e.g., multilocus enzyme electrophoresis, pulsed-field gel electrophoresis). We used automated sequencing of the sic gene encoding streptococcal inhibitor of complement and of a region of the chromosome with direct repeat sequences to unambiguously differentiate 30 M1 isolates recovered from 28 patients in Texas with invasive disease episodes temporally clustered and thought to represent an outbreak. Sequencing of the emm gene was less useful for M1 strain differentiation, and restriction fragment length polymorphism analysis with IS1548 or IS1562 as Southern hybridization probes did not provide epidemiologically useful subtyping information. Sequence polymorphism in the direct repeat region of the chromosome and IS1548 profiling data support the hypothesis that M1 organisms have two main evolutionary lineages marked by the presence or absence of the speA2 allele encoding streptococcal pyrogenic exotoxin A2.

Another toxic shock syndrome. Streptococcal infection is even more dangerous than the staphylococcal form

In the battery of diseases caused by group A streptococci, streptococcal toxic shock syndrome is among the most severe. Its nonspecific presentation and rapid progression require that the treating physician be both knowledgeable and vigilant. Certain signs and symptoms suggest that caution is in order: Pain out of proportion to physical findings may herald deep tissue involvement in a patient who at first glance appears to have cellulitis. Streptococcal infection accompanied by hypotension, confusion, or unexplained acute renal insufficiency is a clue to streptococcal toxic shock syndrome. Treatment consists of antibiotic and supportive care, with aggressive surgical debridement of soft-tissue foci of infection when necessary. Anecdotal evidence suggests that intravenous immunoglobulin may have a place in neutralizing the secreted streptococcal toxins that are thought to mediate features of the disease. At present, even with aggressive therapy, the mortality rate of streptococcal toxic shock syndrome can exceed 50%. Understanding of its pathogenesis is progressing. However, until effective interventions are developed, early detection appears to be the best weapon.

Identification of csrR/csrS, a genetic locus that regulates hyaluronic acid capsule synthesis in group A Streptococcus

The hyaluronic acid capsule of group A Streptococcus (GAS) is an important virulence factor, but little is known about mechanisms that regulate capsule expression. Transposon Tn916 mutagenesis of the poorly encapsulated M-type 3 GAS strain DLS003 produced a transconjugant that exhibited a mucoid colony morphology, reflecting increased hyaluronic acid capsule production. Analysis of chromosomal DNA sequence immediately downstream of the transposon insertion identified two open reading frames, designated csrR and csrS, which exhibited sequence similarity to bacterial two-component regulatory systems. We constructed an in-frame deletion mutation within csrR, which encodes the putative response component. Replacement of the native csrR gene in the DLS003 chromosome with the mutant allele resulted in a sixfold increase in capsule production and a corresponding increase in transcription of the has operon, which contains the essential genes for hyaluronic acid synthesis. Increased capsule production by the csrR mutant strain was associated with enhanced resistance to complement-mediated opsonophagocytic killing in vitro and with a 500-fold increase in virulence in mice. These results establish CsrR as a negative regulator of hyaluronic acid capsule synthesis and suggest that it is part of a two-component regulatory system that influences capsule expression and virulence.

Toxin-mediated streptococcal and staphylococcal disease

After several decades of seemingly decreasing virulence, streptococcal and staphylococcal infections have reemerged as a major source of morbidity and mortality. Within the past 2 decades, not only have well-established diseases such as rheumatic fever begun to reappear. but also many new entities, such as toxic shock syndrome, streptococcal toxic shock syndrome, recurrent toxin-mediated perineal erythema, and recalcitrant erythematous desquamating disorder have been described. Central to the renewed importance of these bacteria has been the production of circulating toxins, which often function as superantigens in causing the clinical manifestations, morbidity and mortality associated with these diseases.

Molecular analysis of the role of the group A streptococcal cysteine protease, hyaluronic acid capsule, and M protein in a murine model of human invasive soft-tissue infection

Human invasive soft-tissue infections caused by group A Streptococcus are associated with significant morbidity and mortality. To investigate the pathogenesis of these serious infections, we characterized the host response to bacterial challenge with an M-type 3 isolate recovered from a patient with necrotizing fasciitis, or with isogenic gene replacement mutants deficient in cysteine protease, hyaluronic acid capsule, or M protein in a murine model of human invasive soft-tissue infection. Animals challenged with the wild-type or cysteine protease-deficient strain developed spreading tissue necrosis at the site of inoculation, became bacteremic, and subsequently died. Histopathologic examination of the necrotic lesion revealed bacteria throughout inflamed subcutaneous tissue. Arterioles and venules in the subcutaneous layer were thrombosed and the overlying tissue was infarcted. In contrast, animals challenged with either an acapsular or M protein-deficient mutant developed a focal area of tissue swelling at the site of inoculation without necrosis or subsequent systemic disease. Histopathologic examination of the soft-tissue lesion demonstrated bacteria confined within a well-formed subcutaneous abscess. We conclude that the group A streptococcal hyaluronic acid capsule and M protein, but not the cysteine protease, are critical for the development of tissue necrosis, secondary bacteremia, and lethal infection in a murine model of human necrotizing fasciitis.

Diagnosis of group A streptococcal necrotizing fasciitis by using PCR to amplify the streptococcal pyrogenic exotoxin B gene

This study evaluated a PCR assay for detection of the streptococcal pyrogenic exotoxin B (speB) gene from tissue biopsy specimens of patients with necrotizing fasciitis. speB was detected in specimens from all 10 patients with necrotizing fasciitis due to group A streptococcus. The assay was negative for all 11 patients without culture or serologic evidence of streptococcal infection. These results suggest that the detection of speB by PCR may be useful for confirming group A streptococcal infection when cultures are negative or not available.

Magnetic resonance imaging in the early diagnosis of group A beta streptococcal necrotizing fasciitis: a case report

Early diagnosis of invasive group A beta streptococcal (GABS) infection has been achieved in a patient using magnetic resonance imaging (MRI) complemented by needle aspiration. Life-saving treatments of GABS infection that include immediate surgical debridement along with the administration of i.v. antibiotics, gamma globulin, and hyperbaric oxygen were then implemented successfully to prevent the development of streptococcal toxic shock syndrome. While MRI is valuable in making early diagnosis of GABS, it should not delay surgical intervention.

Opsonic antibodies to the surface M protein of group A streptococci in pooled normal immunoglobulins (IVIG): potential impact on the clinical efficacy of IVIG therapy for severe invasive group A streptococcal infections

The surface M protein of group A streptococci (GAS) is one of the major virulence factors for this pathogen. Antibodies to the M protein can facilitate opsonophagocytosis by phagocytic cells present in human blood. We investigated whether pooled normal immunoglobulin G (IVIG) contains antibodies that can opsonize and enhance the phagocytosis of type M1 strains of GAS and whether the levels of these antibodies vary for different IVIG preparations. We focused on the presence of anti-M1 antibodies because the M1T1 serotype accounts for the majority of recent invasive GAS clinical isolates in our surveillance studies. The level of anti-M1 antibodies in three commercial IVIG preparations was determined by enzyme-linked immunosorbent assay (ELISA), and the opsonic activity of these antibodies was determined by neutrophil-mediated opsonophagocytosis of a representative M1T1 isolate. High levels of opsonic anti-M1 antibodies were found in all IVIG preparations tested, and there was a good correlation between ELISA titers and opsonophagocytic activity. However, there was no significant difference in the levels of opsonic anti-M1 antibodies among the various IVIG preparations or lots tested. Adsorption of IVIG with M1T1 bacteria removed the anti-M1 opsonic activity, while the level of anti-M3 opsonophagocytosis was unchanged. Plasma was obtained from seven patients with streptococcal toxic shock syndrome who received IVIG therapy, and the level of anti-M1 antibodies was assessed before and after IVIG administration. A significant increase in the level of type M1-specific antibodies was found in the plasma of all patients who received IVIG therapy (P < 0.006). The results reveal another potential mechanism by which IVIG can ameliorate severe invasive group A streptococcal infections.

Hypervariability generated by natural selection in an extracellular complement-inhibiting protein of serotype M1 strains of group A Streptococcus

In many countries, M1 strains of the human pathogenic bacterium group A Streptococcus are the most common serotype recovered from patients with invasive disease episodes. Strains of this serotype express an extracellular protein that inhibits complement [streptococcal inhibitor of complement (Sic)] and is therefore believed to be a virulence factor. Comparative sequence analysis of the 915-bp sic gene in 165 M1 organisms recovered from diverse localities and infection types identified 62 alleles. Inasmuch as multilocus enzyme electrophoresis and pulsed-field gel electrophoresis previously showed that most M1 organisms represent a distinct streptococcal clone, the extent of sic gene polymorphism was unexpected. The level of polymorphism greatly exceeds that recorded for all other genes examined in serotype M1 strains. All insertions and deletions are in frame, and virtually all nucleotide substitutions alter the amino acid sequence of the Sic protein. These molecular features indicate that structural change in Sic is mediated by natural selection. Study of 70 strains recovered from two temporally distinct epidemics of streptococcal infections in the former East Germany found little sharing of Sic variants among strains recovered in the different time periods. Taken together, the data indicate that sic is a uniquely variable gene and provide insight into a potential molecular mechanism contributing to fluctuations in streptococcal disease frequency and severity.

Bacterial arthritis due to beta-hemolytic streptococci of serogroups A, B, C, F, and G. Analysis of 23 cases and a review of the literature

The clinical features, essential laboratory findings, management, and outcome of all 23 cases of septic arthritis caused by different serogroups of beta-hemolytic streptococcus (BHS) seen at the Stanford Medical Center, Stanford, CA, from July 1, 1985, through October 31, 1996, were reviewed and compared to those found in the literature. Group A streptococci (GAS) accounted for 9 (40%) of our cases; group B (GBS), for 7 (30%); and Group G (GGS), for 7 (30%). No cases were caused by Group C (GCS) or F (GFS) during this period. During the same period, GAS accounted for 66 (33%) of 200 cases of bacteremia due to BHS, GBS, for 98 (49%); GCS, for 12 (6%); GFS, for 4 (2%); and GGS, for 20 (10%). A review of potential risk factors revealed that, with the exception of GGS, male and female patients were almost equally distributed among each of the serogroups. Patients aged 50 years and older comprised 56%-77% of each group. Associated conditions and risk factors were present among most patients (19/23, 83%); autoimmune diseases and a chronic skin wound or trauma were notably present among patients with GAS, while diabetes mellitus and malignancy were more common among patients with GBS. Infected prosthetic implants were present in 7 patients, including 4/7 patients with GGS. All patients had positive cultures of synovial fluid, and 11/23 (49%) had positive blood cultures (GAS, 5/9; GBS, 6/7; and GGS, 0/7). The clinical presentation and hospital course of patients infected with the different serogroups varied. Patients infected with GAS had the most severe disease and those with GGS the least severe. Necrotizing fascitis, shock, DIC, and admission to the intensive care unit were found only among patients infected with GAS. Despite aggressive management with antimicrobial therapy and surgery, 4/23 patients died (3 patients with GAS; 1 with GBS). The isolates from our patients were not available for study; investigations by others of the biology of BHS suggest that the production of 1 or more of the streptococcal pyrogenic exotoxins by isolates of GAS may account for the differences in the severity of disease among our patients with septic arthritis caused by different serogroups of BHS. Although septic arthritis due to BHS is uncommon, such patients provide a valuable model to study features of the host-parasite interaction that may contribute to the observed differences in severity of disease.

Streptococcus pyogenes bacteraemia: a 27-year study in a London teaching hospital

The clinical and epidemiological features of 120 episodes of Streptococcus pyogenes bacteraemia in St. Thomas' Hospital between 1970 and 1997 were analysed. One-third of episodes were nosocomial. M1 was the most common serotype, and 29% of strains were non-typable. There was a variety of presenting features, but nearly half of the patients had cellulitis, 15% were shocked, and 6% had necrotic infections. There was no focus of infection in 13%. 54% of patients had an underlying disease, and 23% of infections were associated with a medical procedure or device. The mortality rate was 19%, and was associated with shock, coma, no focus of infection, and underlying disease. Since 1989, the annual incidence has more than doubled, and M1 strains and necrotic infections have increased, but the mortality rate and the proportion of patients presenting with shock have decreased, and the increase in cases involved many different M-types.

[Virus-bacteria co-infections]

Influenza is the best known model of bacterial-viral co-infection. Epidemics of influenza result in an increased hospital admission rate for bacterial pneumonia due to pneumococcus, Haemophilus influenzae and Staphylococcus aureus. Similarly, an increased incidence of meningococcal diseases, particularly severe forms, follows the influenza outbreaks, with a two week delay. Though the precise mechanism is not known, the depression of host's phagocytes bactericidal activity by the influenza virus seems to be involved. An increased incidence of invasive group A beta hemolytic streptococcal infections, particularly necrotizing fasciitis and toxic shock syndrome, is also observed in relation with chickenpox. The reason for this association is unclear and appears not to be limited to the disruption of the cutaneous barrier which leads to the cutaneous infections in this disease. Bacterial-viral co-infection is not a justification for a systematic antibiotic prescription in viral diseases. Severe bacterial disease will be best prevented through viral immunization, thus encouraging the development of viral vaccines and immunization campaigns.

Ibuprofen and skin and soft tissue superinfections in children with varicella

PURPOSE

To investigate the possible association between ibuprofen use and dermatologic superinfections among children with recent varicella infection.

METHODS

A retrospective cohort study of children in Harvard Pilgrim Health Care, a health maintenance organization in New England, was conducted. Outcomes and exposures of interest were identified from automated medical and pharmacy records. Exposure was defined by dispensing of ibuprofen before varicella to avoid potential confounding by indication.

RESULTS

Between July 1, 1990 and September 30, 1994, 89 superinfections developed among 7,013 cases of varicella. The 30-day risk of superinfection was 7.2/10(3) cases (95% CI = 5.8-8.8/10(3) cases). Four of 169 children dispensed ibuprofen within 180 days of varicella developed superinfection. Relative to children without prior use, children with ibuprofen dispensed in the month prior to varicella were 3.1 times more likely to be diagnosed with a superinfection (95% CI = 0.1-19.7; P-value: 0.31). Restriction of outcomes to superinfections treated with systemic antibiotics increased the odds ratio to 5.1 (95% CI = 0.1-32.5; P-value: 0.22).

CONCLUSIONS

The results of this study are consistent with a broad range of effects including no association and suggest that further study is needed.

Necrotizing soft tissue infections reported with nonsteroidal antiinflammatory drugs

BACKGROUND

Recent reports of necrotizing fasciitis in children with varicella who received a nonsteroidal antiinflammatory drug (NSAID) recall earlier concerns regarding the possibility of relationships between infections and NSAIDs. We searched the Food and Drug Administration's Spontaneous Reporting System (SRS) for necrotizing soft tissue infections reported in conjunction with the use of NSAIDs, to identify common features.

METHODS

A computer search of NSAID listings in the adverse event database recovered reports with codes for selected infection and necrosis-related diagnostic categories. From review of individual reports classified under these codes, cases were selected if the terms "necrotizing fasciitis," "necrotic," or "gangrenous" appeared in the adverse drug reaction description. Demographic, drug use, and disease course information were gathered.

FINDINGS

Thirty-three cases were identified, of which 10 were fatal. Over two-thirds of the patients were younger than 40 years. Thirty (91%) had a possible portal of entry for infection. Most received NSAIDs for acute conditions including varicella, trauma, and postoperative or postpartum pain; 7 received an NSAID by intramuscular injection. Specific NSAIDs accounting for most reports were also among those likely to be most heavily used in the relevant populations.

INTERPRETATION

Common features of these rare case reports of necrotizing soft tissue infections with NSAID use include characteristics such as age, portal of infection entry, indication for NSAID use, route of administration, and individual NSAIDs. The total number of SRS cases does not suggest that necrotizing infection is frequent with NSAIDs or likely without other risk factors. Controlled observational studies would help to define any causal contribution of these factors to the evolution of severe infection.

Population-based surveillance for group A streptococcal necrotizing fasciitis: Clinical features, prognostic indicators, and microbiologic analysis of seventy-seven cases. Ontario Group A Streptococcal Study

PURPOSE

To determine the incidence of group A streptococcal necrotizing fasciitis in Ontario, Canada, and to describe the clinical features, outcome, and microbiologic characteristics of this infection.

PATIENTS AND METHODS

Prospective, population-based surveillance for invasive group A streptococcal infections was conducted in Ontario from November 1991 to May 1995. All 77 patients meeting clinical and/or histopathologic criteria for streptococcal necrotizing fasciitis were included. Demographic and clinical information was obtained by patient interviews and chart review. Group A streptococci were characterized by M-protein and T-agglutination typing, and polymerase chain reaction (PCR) detection of streptococcal pyrogenic exotoxin genes A and C (speA; speC).

RESULTS

The incidence of group A streptococcal necrotizing fasciitis increased during the study from 0.085 per 100,000 population in the first year to 0.40 per 100,000 population in the last year (P < 0.001). The median age of cases was 57.5 years and the rate of disease increased with increasing age. Seventy-nine percent of cases were community-acquired, 11% were nosocomial, and 10% were acquired in a nursing home. Forty-seven percent of cases were associated with the presence of streptococcal toxic shock syndrome (Strep TSS) and 46% were bacteremic. Thirty-four percent of cases died and mortality was correlated with increasing age (P = 0.006), presence of hypotension (P = 0.01), and bacteremia (P = 0.03). The most common streptococcal serotypes were M1 (35%) and M3 (25%). Forty-one percent of strains possessed the speA gene and 30% the speC gene. Outcome was not correlated with M-type or the presence of spe genes.

CONCLUSIONS

The incidence of necrotizing fasciitis caused by group A streptococcus increased in Ontario between 1992 and 1995. Elderly individuals were more likely to acquire the disease and to die from it. Mortality because of streptococcal necrotizing fasciitis was also associated with the presence of hypotension, Strep TSS, or bacteremia, but not with M-type or the presence of pyrogenic exotoxin genes.

Group A streptococcal bacteremia. A 10-year prospective study

In this paper we present a prospective evaluation of 100 patients with Group A Streptococcal (GAS) bacteremia evaluated in our hospital over a 10-year period. Sixty-two patients were intravenous drug users (IVDU); all but 1 of these had an obvious cutaneous portal of entry related to the injection of illicit drugs. Twenty-seven patients had infectious metastasis, and the presence of septic pulmonary embolism was associated with suppurative phlebitis. Four of these patients had endocarditis. In the non-IVDU group, 24 patients had an underlying disease, and 12 were immunosuppressed. In 14 cases the infection was of hospital acquisition; in 35% infection was related to medical manipulations. Comparing the IVDU and non-IVDU groups, GAS bacteremia in IVDU patients is associated with a more benign outcome, a longer time of evolution before diagnosis, and a lower frequency of septic shock and mortality than in non-IVDU patients. Although in the univariate analysis GAS bacteremia was associated with several variables, in the multivariate analysis only the presence of shock and nosocomial acquisition of the infection were independently associated with a fatal outcome. Fifty-two patients were infected with human immunodeficiency virus (HIV); 5 of these were in the non-IVDU group. During the last 5 years of study, GAS bacteremia in our hospital was 39 times more frequent in HIV-infected patients than in patients without HIV. Nine patients presented clinical criteria corresponding to Streptococcal toxic shock syndrome (STSS), although its incidence was lower in the IVDU group. In the non-IVDU group, STSS was more frequent in patients with a necrotizing portal of entry, an age between 20 and 40 years, women, and when the origin of the infection was the skin or soft tissue. Six patients with STSS died, and death was associated with the presence of necrotizing lesions and lower counts of white cells, platelets, or hemoglobin.

A clinical study of beta-haemolytic groups A, B, C and G streptococcal bacteremia in adults over an 8-year period

All of the 88 episodes of beta-haemolytic streptococcal bacteremia (2.9% of all bacteremias) in adult patients during the years 1987-94 in a university hospital were reviewed. 38 bacteremias (43%) were caused by group A, 24 (27%) by group B, 3 (4%) by group C, and 23 (26%) by group G beta-haemolytic streptococcal. There was a statistically significant increase in group A and decrease in group C and G bacteremias (p < 0.02) compared to an earlier 8-year period in the same hospital, although the total number of streptococcal bacteremias remained the same. The most common T types of group A streptococcal strains were T11 (26%), T28 (14%), T6 and T1 (11% each), and T12 (8%). Cardiovascular disease, skin lesions, malignancy, and alcohol abuse were the most common underlying conditions. The most usual types of infection were skin (47%) and respiratory tract infections (23%). The overall mortality was 16%. It was highest in group A (24%) and lowest in group C (0%), 38% of patients with pneumonia died. All streptococcal strains were sensitive to penicillin, vancomycin, and cephalosporins. 11% of group A and 12% of all the strains had decreased sensitivity to erythromycin, 14 and 38% to tetracycline, and 0 and 2% to clindamycin, respectively.