Invasive group A streptococcus infections

Two cases of delayed diagnosis of postpartal streptococcal toxic shock syndrome

BACKGROUND

Puerperal sepsis due to group A beta-hemolytic streptococcal (GAS) toxic shock syndrome is associated with very high morbidity and mortality. Luckily it is now rare, but diagnosis is not always easy. This report demonstrates the problem of recognizing this disease, and summarizes the current knowledge on the pathomechanism and management of streptococcal toxic shock syndrome.

CASE

Two cases of postpartum streptococcal toxic shock syndrome due to GAS are described. In both cases the correct diagnosis was delayed for several days. The first patient was sent home with the diagnosis of German measles; the second patient was transferred to our neurological intensive care unit with the diagnosis of meningitis. Both patients were admitted to the intensive care unit in profound shock, both developed multiple organ failure, and one patient died.

CONCLUSIONS

GAS may produce virulence factors that cause host tissue pathology. Besides aggressive modern intensive care treatment, early diagnosis and correct choice of anti-streptococcal antibiotics are crucial. A possible adverse effect of non-steroidal anti-inflammatory agents requires confirmation in a multicenter study.

Group A streptococcal toxic shock syndrome developing in the third trimester of pregnancy

BACKGROUND

Group A streptococcal (GAS) toxic shock syndrome (TSS) is an uncommon, but life-threatening infection during pregnancy and should be considered in rapid onset of shock. Most cases described in the literature have occurred in the puerperium. We report a case of GAS TSS occurring during the third trimester of pregnancy in a previously healthy woman.

CASE

A 31-year-old female, who was 34 weeks pregnant, presented with fevers and a prodromal 'flu-like' illness. She rapidly developed shock and multiorgan failure. Blood cultures revealed GAS bacteremia and the patient met criteria for streptococcal TSS. Despite her eventual recovery, her infant died on postpartum day 15 as a consequence of the mother's TSS.

CONCLUSIONS

This case is unusual in that there were no identifiable initiating events or source of the streptococcal infection, and the TSS developed during pregnancy rather than after delivery. Early recognition of GAS infections is important given the rapid onset and high morbidity and mortality associated with these infections. This is the first reported case utilizing intravenous immunoglobulin for GAS TSS in the puerperium.

[Severe cutaneous Streptococcus pyogenes infections in the child: results of a multicenter survey]

To assess pediatric cases of severe cutaneous infections due to Streptococcus pyogenes. Since the beginning of 1980, the incidence of cellulitis and necrotizing fasciitis due to S. pyogenes has increased in adults. Serotyping of obtained isolates are in most cases M1, M3 or M5 protein.

PATIENTS AND METHOD

A retrospective (1990-2000) survey was carried out in pediatric hospital centers.

RESULTS

Three cases of necrotizing fasciitis and 15 of cellulitis were observed. In 30% of the cases, vancella lesions were associated; in the other cases, minor wounds were the site of the infection. Bacteriologic diagnosis was made by local samples in 14 cases; blood cultures were positive in four cases. In 11 cases, initial intravenous treatment consisted of third generation cephalosporin, in six cases of penicillin M or G and in one case of fusidic acid. In the second time, penicillin M was perfused in the majority of the cases. Mean duration of intravenous antibiotics perfusion was 15 days. There were no sequelae or death in this survey.

CONCLUSIONS

Despite this study had limited epidemiological characteristics, it confirms that these two infections are rare. The frequency is probably underestimated, due to the difficulty in performing a diagnosis. The major site of infection was the varicella lesion. These two infections are so similar that it is frequent to mistake one infection for the other. Nonsteroidal anti-inflammatory drugs and site of infections did not influence prognosis. The treatment of cellulitis is penicillinotherapy whereas in necrotizing fasciitis early major surgery is often correlated with the rate of survival.

Waterhouse-Friderichsen syndrome after infection with group A streptococcus

We report a case of Waterhouse-Friderichsen syndrome associated with group A streptococcus (GAS) toxic shock syndrome in a previously healthy man. The patient presented with neck pain and fevers of 2 days' duration. Computed tomography of the neck revealed a mass in the retropharyngeal space, suggesting an abscess. Despite prompt treatment with appropriate antibiotics, the patient experienced a fulminant course and died within 8 hours of presentation. Antemortem blood cultures grew GAS positive for exotoxins A, B, and C. Postmortem examination revealed bilateral adrenal hemorrhage, consistent with Waterhouse-Friderichsen syndrome. Immunohistochemical analysis of the adrenal glands revealed the presence of GAS antigens. However, no disseminated intravascular coagulation was evident. This case demonstrates that adrenal hemorrhage can occur without associated coagulopathy and may result directly from the action of bacterial toxins.

Group A Streptococcus (GAS) Soft-tissue Infections: A Lethal Organism on the Rise

Several reports over the past decade have suggested that there has been an increase in the number of invasive streptococcal infections with young children and the elderly being at the highest risk. We evaluated the incidence of group A Streptococcus (GAS) and compared it with historic data collected at our institution. Prospective data were collected on patients diagnosed with GAS (with and without shock) admitted to a tertiary-care center from July 1995 to July 2000. Each patient was followed by an infectious disease specialist throughout the hospital stay. Definitions of streptococcal toxic shock syndrome (STSS) developed by the Centers for Disease Control and Prevention were used. Thirty-eight patients (mean age of 39 ± 12) presenting with GAS soft-tissue infections were admitted to our institution over a 5-year period (7.6 patients per year). Fourteen (37%) were diagnosed with STSS. This represents a greater than fourfold increase in the average number of cases per year of patients diagnosed with GAS and a nearly 4.5 times greater increase in the annual number of patients diagnosed with STSS. The overall mortality of patients diagnosed with GAS was 13 per cent, which increased to 36 per cent in patients diagnosed with STSS. We conclude that there has been a significant increase in the incidence of GAS soft-tissue infections over the past 5 years at our institution. This may represent a new virulent strain, as the majority of these infections did not occur in typical high-risk patients at the extremes of their lives. Further epidemiologic population-based studies are needed to further delineate the severe nature of this problem.

Infectious disease update

Many newly described or "re-emerging" infectious diseases may present to the dermatologist, often with potentially life-threatening implications. Prompt recognition and early intervention can greatly diminish the morbidity and mortality associated with these diseases.

Fba, a novel fibronectin-binding protein from Streptococcus pyogenes, promotes bacterial entry into epithelial cells, and the fba gene is positively transcribed under the Mga regulator

In infection by Streptococcus pyogenes, fibronectin (Fn)-binding proteins play important roles as adhesins and invasins. Here, we present a novel Fn-binding protein of S. pyogenes that exhibits a low similarity to other Fn-binding proteins reported. After searching the Oklahoma Streptococcal Genome Sequencing Database for open reading frames (ORFs) with an LPXTG motif, nine ORFs were found among those recognized as putative surface proteins, and one of them was designated as Fba. The fba gene was found in M types 1, 2, 4, 22, 28 and 49 of S. pyogenes, but not in other serotypes or groups of streptococci. Fba, a 37.8 kDa protein, possesses three or four proline-rich repeat domains and exhibits a high homology to FnBPA, the Fn-binding protein of Staphylococcus aureus. Recombinant Fba exhibited a strong binding ability to Fn. In addition, Fba-deficient mutants showed diminished invasive capabilities to HEp-2 cells and low mortality in mice following skin infection. The fba gene was located downstream of the mga regulon and analysis using an mga-inactivated mutant revealed that it was transcribed under the control of the Mga regulator. These results indicate that Fba is a novel protein and one of the important virulence factors of S. pyogenes.

Orbital streptococcal gangrene and AIDS

Streptococcal gangrene can present to the ophthalmologist as a fulminant orbital cellulitis involving the eyelids, globe and orbit. Compromised vision is likely, as well as serious systemic illness and death. It commonly affects young and healthy hosts and, prior to this presentation, has never been reported in a patient with HIV infection. We studied a case of streptococcal gangrene of the eyelids and orbit in a patient with AIDS. The infection was treated with debridement and intravenous antibiotics, and showed eventual improvement with the exception of visual function. A biopsy of the lesion exhibited extensive soft tissue necrosis with a predilection for blood vessels, resulting in thrombosis and infarction. Cultures grew out heavy group A beta-hemolytic Streptococcus. This case illustrates that streptococcal gangrene can occur with HIV, although to date this combination has been rare. Early diagnosis is crucial and includes recognition of incipient cutaneous, histopathological and anterior segment ischemia signs.

Complementation of a speA negative Streptococcus pyogenes with speA: effects on virulence and production of streptococcal pyrogenic exotoxin A

We have shown previously that an isogenic SPEA-negative Streptococcus pyogenes strain did not attenuate virulence in a murine model of necrotizing fasciitis. The aim of this study was to confirm that streptococcal pyrogenic exotoxin A (SPEA) is not crucial for streptococcal invasiveness in murine invasive infection. The SPEA-negative S. pyogenes (H326) was complemented with speA extra-chromosomally to create strain H361 which produced 2.2-fold more SPEA compared with the parental speA(+)wild-type (H305). The growth phase-regulated expression of SPEA in vitro was unaffected in this strain. Complementation with speA resulted in reduced virulence and bacterial counts in invasive murine infection. SPEA production was quantitated from muscle tissue of infected mice. However, H361 did not produce more SPEA than H305 in vivo. We conclude that SPEA does not play a key role in invasive murine streptococcal infection.

Identification and characterization of a novel secreted immunoglobulin binding protein from group A streptococcus

Immunoglobulin binding proteins are one of several pathogenicity factors which have been associated with invasive disease caused by group A streptococci. The surface-bound M and M-like proteins of Streptococcus pyogenes are the most characterized of these immunoglobulin binding proteins, and in most cases they bind only a single antibody class. Here we report the identification of a novel non-M-type secreted protein, designated SibA (for secreted immunoglobulin binding protein from group A streptococcus), which binds all immunoglobulin G (IgG) subclasses, the Fc and Fab fragments, and also IgA and IgM. SibA has no significant sequence homology to any M-related proteins, is not found in the vir regulon, and contains none of the characteristic M-protein regions, such as the A or C repeats. Like M proteins, however, SibA does have relatively high levels of alanine, lysine, glutamic acid, leucine, and glycine. SibA and M proteins also share an alpha-helical N-terminal secondary structure which has been previously implicated in immunoglobulin binding in M proteins. Evidence presented here indicates that this is also the case for SibA. SibA also has regions of local similarity with other coiled-coil proteins such as Listeria monocytogenes P45 autolysin, human myosin heavy chain, macrogolgin, and Schistoma mansoni paramyosin, some of which are of potential significance since cross-reactive antibodies between myosin proteins and M proteins have been implicated in the development of the autoimmune sequelae of streptococcal disease.

Antibiotic prophylaxis for group A streptococcal burn wound infection is not necessary

BACKGROUND

Historically, group A beta-hemolytic streptococci (GAS) burn wound infection has been a major source of morbidity and mortality in burn patients and has prompted the prophylactic administration of antibiotics to children with burns. Wound monitoring, surveillance cultures, and early excision of deep wounds may have changed this. Our objective in this project was to determine the efficacy of routine antibiotic prophylaxis in the era of early excision and closure of deep burn wounds.

METHODS

Two cohorts of burned children were compared: all children admitted during calendar years 1992 through 1994 (group 1) and during calendar years 1995 through 1997 (group 2). All group 1 children received routine GAS antibiotic prophylaxis. Only those group 2 children with documented positive admission or surveillance cultures for GAS were treated.

RESULTS

There were 511 children in group 1 and 406 children in group 2. They were well matched for age (4.7 +/- 0.21 years vs. 5.3 +/- 0.26 years, p = 0.06) and burn size (11.0% +/- 0.7% vs. 12.4% +/- 0.8%, p = 0.18). GAS species were recovered at admission or during hospitalization from 11 (2.6%) of group 1 children and 18 (4.4%) of group 2 children (p = 0.05), indicating a marginally higher rate of carriage in group 2. Nevertheless, in group 1 there were three (0.6%) who developed GAS wound infection and in group 2 there were four (0.98%, p = 0.71). The incidence of GAS infection in those patients with positive admission cultures was three (27%) of group 1 and four (22%) of group 2. No child developed fulminant GAS infection.

CONCLUSION

Routine antibiotic prophylaxis of burn wounds in children in not effective in further reducing a low baseline incidence of GAS wound infection if admission screening by culture is used to identify those children who carry the organism and early excision of deep burns is practiced.

A case of toxic shock-like syndrome presenting with serious hypoproteinaemia because of a protein-losing gastroenteropathy

A 37-year-old man was admitted to our hospital because of toxic shock-like syndrome (TSLS) induced by Streptococcus pyogenes. After the pathogenic bacteria had been eradicated, serious diarrhoea appeared and a protein-losing gastroenteropathy developed. An immunohistochemical study of the biopsy specimens of both small and large intestines revealed the infiltration of T-lymphocytes, predominantly CD8+ cells, into the lamina propria of affected mucosa, villus atrophy and crypt hyperplasia. Considering these histological findings, some immunological mechanism which lead the activation of cytotoxic T-lymphocytes may play an important role in the pathogenesis of this rare intestinal manifestation of TSLS.

The emergence of erythromycin-resistant Streptococcus pyogenes in Seoul, Korea

High frequencies of erythromycin-resistant streptococci were reported in Japan in the mid-1970s, and in Finland in the late 1980s, related to an increase in the consumption of macrolide antibiotics in these countries. The frequency of erythromycin-resistant Streptococcus pyogenes was reported to be only 2% in 1994, but we know that the susceptibility of the strains to antibiotics had not been tested routinely. We studied the resistance rates of Streptococcus pyogenes to various antibiotics in Seoul, Korea, where antibiotics could be purchased without prescription. From January through December, 1998, 92 isolates of group A streptococci were collected from inpatients and outpatients with pharyngotonsillitis or invasive streptococcal infections, from institutions in five different geographic areas of Seoul; one pediatric clinic, three university hospitals, and one general hospital. All isolates were serotyped by T-agglutination, and minimum inhibitory concentrations (MICs) were determined by agar dilution methods, according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). The most common T-serotype was T12 (44.6%), followed by T4 (19.6%). All the isolates tested were susceptible to penicillin, vancomycin, and cefotaxime. However, 38 isolates (41.3%) were resistant to erythromycin, 32 (34.8%) were resistant to clindamycin, and 48 (52.1%) were resistant to tetracycline. Twenty-seven of 41 isolates serotyped T12 and 3 of 18 isolates serotyped T28 were multiresistant to erythromycin, clindamycin, and tetracycline. Almost half of the isolates obtained from the five different areas in Seoul showed erythromycin resistance in Streptococcus pyogenes. Routine monitoring of antibiotic susceptibility tests and further extensive nationwide surveys are needed to determine the frequency and the extent of the spread of resistant strains in various geographic regions in Korea.

Repression of virulence genes by phosphorylation-dependent oligomerization of CsrR at target promoters in S. pyogenes

csrRS encodes a two-component regulatory system that represses the transcription of a number of virulence factors in Streptococcus pyogenes, including the hyaluronic acid capsule and pyrogenic exotoxin B. CsrRS-regulated virulence factors have diverse functions during pathogenesis and are differentially expressed throughout growth. This suggests that multiple signals induce CsrRS-mediated gene regulation, or that regulated genes respond differently to CsrR, or both. As a first step in dissecting the csrRS signal transduction pathway, we determined the mechanism by which CsrR mediates the repression of its target promoters. We found that phosphorylated CsrR binds directly to all but one of the promoters of its regulated genes, with different affinities. Phosphorylation of CsrR enhances both oligomerization and DNA binding. We defined the binding site of CsrR at each of the regulated promoters using DNase I and hydroxyl radical footprinting. Based on these results, we propose a model for differential regulation by CsrRS.

Toxic shock-like syndrome with flu-like prodrome: a possible role of 'enhancing tissue focus' for streptococcal toxic shock

We describe three patients with invasive group A streptococcal infection, admitted during the 3 months between November 1996 and February 1997. All patients were previously healthy Japanese women who developed a profound shock, with a rapidly fatal outcome, after experiencing flu-like symptoms. All cases conformed to the case definition of toxic shock-like syndrome (TSLS).Currently, the pathogenic mechanism of TSLS remains unclear. Known microbial virulence factors can not sufficiently explain the occurrence of TSLS, and it has been generally considered that host factors may be contributory. On pathological examination, each patient had one organ or tissue that was most severely involved: Case 1 a non-penetrating trauma; Case 2 a pregnant uterus; and Case 3 a pulmonary lesion reminiscent of lymphocytic interstitial pneumonia. On the basis of clinicopathological features of these cases, we propose that the coexistence of 'enhancing tissue focus' may be one of host factors for the progression of TSLS in patients infected with non-invasive GAS.

Streptococcus pneumoniae: a rare skin pathogen?

Streptococcus pneumoniae is a rare cause of skin infections in adults. We present three cases and a review of the literature on this infection. Nine of the 42 (21%) cases occurred in previously healthy individuals without predisposing conditions. The majority of cases (88%) had bacteraemia. More than half the cases (22/42, 52%) required surgical intervention in addition to antimicrobial therapy.

Identification and characterization of a second extracellular collagen-like protein made by group A Streptococcus: control of production at the level of translation

A recent study found that group A Streptococcus (GAS) expresses a cell surface protein with similarity to human collagen (S. Lukomski, K. Nakashima, I. Abdi, V. J. Cipriano, R. M. Ireland, S. R. Reid, G. G. Adams, and J. M. Musser, Infect. Immun. 68:6542-6553, 2000). This streptococcal collagen-like protein (Scl) contains a long region of Gly-X-X motifs and was produced by serotype M1 GAS strains. In the present study, a second member of the scl gene family was identified and designated scl2. The Scl2 protein also has a collagen-like region, which in M1 strains is composed of 38 contiguous Gly-X-X triplet motifs. The scl2 gene was present in all 50 genetically diverse GAS strains studied. The Scl2 protein is highly polymorphic, and the number of Gly-X-X motifs in the 50 strains studied ranged from 31 in one serotype M1 strain to 79 in serotype M28 and M77 isolates. The scl1 and scl2 genes were simultaneously transcribed in the exponential phase, and the Scl proteins were also produced. Scl1 and Scl2 were identified in a cell-associated form and free in culture supernatants. Production of Scl1 is regulated by Mga, a positive transcriptional regulator that controls expression of several GAS virulence factors. In contrast, production of Scl2 is controlled at the level of translation by variation in the number of short-sequence pentanucleotide repeats (CAAAA) located immediately downstream of the GTG (Val) start codon. Control of protein production by this molecular mechanism has not been identified previously in GAS. Together, the data indicate that GAS simultaneously produces two extracellular human collagen-like proteins in a regulated fashion.

The use of 5% mafenide acetate solution in the postgraft treatment of necrotizing fasciitis

Twenty-nine patients with necrotizing fasciitis who were treated with 5% mafenide acetate solution (MAS) as an adjunct after grafting were compared with 45 patients treated without MAS. Statistical analysis of differences was obtained through P values by chi2 testing. The MAS+ (M) and MAS- (C) groups were similar in percent skin deficit (M = 7.5%; C = 9.8%), with the extremity being the most common area of infection. Streptococcus was the most common single organism but polymicrobial infections were the most prevalent (M = 48%; C = 58%). Patients with necrotizing fasciitis treated with MAS had fewer debridements per patient (M = 3.7; C = 5.4), fewer closure procedures (average per patient: M = 1.2; C = 1.73) and a higher percent of first-time closures (83 vs 59%; chi2 = 4.26; P = 0.039). There is a trend toward a lower mortality rate (3.4 vs 13%; chi2 = 2.00; P = 0.158). We conclude that MAS is a useful adjunct in necrotizing fasciitis wound care protocols.

Severe group A streptococcal infection and streptococcal toxic shock syndrome

PURPOSE

To review the literature on group A streptococcal toxic shock syndrome, (STSS).

DATA SOURCE

Medline and EMBASE searches were conducted using the key words group A streptococcal toxic shock syndrome, alone and in combination with anesthesia; and septic shock, combined with anesthesia. Medline was also searched using key words intravenous immunoglobulin, (IVIG) and group A streptococcus, (GAS); and group A streptococcus and antibiotic therapy. Other references were included in this review if they addressed the history, microbiology, pathophysiology, incidence, mortality, presentation and management of invasive GAS infections. Relevant references from the papers reviewed were also considered. Articles on the foregoing topics were included regardless of study design. Non-English language studies were excluded. Literature on the efficacy of IVIG and optimal antibiotic therapy was specifically searched.

PRINCIPAL FINDINGS

Reports of invasive GAS infections have recently increased. Invasive GAS infection is associated with a toxic shock syndrome, (STSS), in 8-14% of cases. The STSS characteristically results in shock and multi-organ failure soon after the onset of symptoms, and is associated with a mortality of 33-81%. Many of these patients will require extensive soft tissue debridement or amputation in the operating room, on an emergency basis. The extent of tissue debridement required is often underestimated before skin incision.

CONCLUSIONS

Management of STSS requires volume resuscitation, vasopressor/inotrope infusion, antibiotic therapy and supportive care in an intensive care unit, usually including mechanical ventilation. Intravenous immunoglobulin infusion has been recommended. Further studies are needed to define the role of IVIG in STSS management and to determine optimal anesthetic management of patients with septic shock.

Relative neutralizing activity in polyspecific IgM, IgA, and IgG preparations against group A streptococcal superantigens

In this study we compared the ability of different immunoglobulin (Ig) preparations containing IgG, IgM, and/or IgA to neutralize the activity of streptococcal pyrogenic exotoxin A (SpeA) or culture supernatant from a clinical group A streptococcal isolate. All Ig preparations markedly inhibited the mitogenic and cytokine-inducing activity of SpeA and culture supernatant at concentrations of 0.05-0.5 mg/mL, and at 0.5 mg/mL, most caused 95-100% inhibition of both stimuli. A significantly higher (P< or =.05) inhibition of SpeA was achieved by Pentaglobin (IgG, IgM, and IgA) and IgAbulin (IgA and IgG), as compared with pure IgG preparations. IgM- and IgA-enriched preparations had significantly higher inhibitory activity against SpeA than against culture supernatant, whereas the reverse was true for the IgG preparations (P< or =.05). The data show that IgM and IgA are potent inhibitors of specific streptococcal superantigens. These findings may have implications for the optimization of immunotherapy in invasive streptococcal infections.

Resistance to multiple fluoroquinolones in a clinical isolate of Streptococcus pyogenes: identification of gyrA and parC and specification of point mutations associated with resistance

A strain of Streptococcus pyogenes resistant to multiple fluoroquinolones was isolated from the blood of an immunocompromised patient. Resistance to fluoroquinolones in S. pyogenes has not been previously studied. Compared to 10 sensitive strains of S. pyogenes, the fluoroquinolone-resistant clinical isolate of S. pyogenes presented point mutations in gyrA, predicting that serine-81 was changed to phenylalanine and that methionine-99 was changed to leucine, and in parC, predicting that serine-79 was changed to tyrosine. The mechanism of fluoroquinolone resistance in this isolate of S. pyogenes appears to be analogous to previously reported mechanisms for Streptococcus pneumoniae.

Contact activation in shock caused by invasive group A Streptococcus pyogenes

OBJECTIVES

The aim of this study was to characterize abnormalities of coagulation in mice with experimental, invasive group A, streptococcal shock, in an attempt to explain the prolongation of the activated partial thromboplastin time identified in patients with streptococcal toxic shock syndrome.

DESIGN

A longitudinal descriptive animal model study of coagulation times and single coagulation factors in mice infected with Streptococcus pyogenes. This was followed by an experimental study to determine whether streptococci or streptococcal products could activate the human contact system in vitro.

SETTING

University infectious diseases and hemostasis molecular biology laboratories.

SUBJECTS

CD1 outbred mice.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Coagulation times, single factor assays, and bradykinin assays were conducted on murine plasma at different times after streptococcal infection and compared with uninfected mice. In experiments in which streptococcal products were co-incubated with human plasma, we compared coagulation times, single factor assays, and activities against a range of chromogenic substrates with control plasma. In a murine model of streptococcal necrotizing fasciitis, the activated partial thromboplastin times were significantly prolonged in infected mice compared with controls, whereas prothrombin times were normal, suggesting an isolated abnormality of the intrinsic pathway. Bleeding was not seen. Prolongation of activated partial thromboplastin time was associated with reduced factor XII and prekallikrein, whereas levels of factors VIII, IX, XI, and high molecular weight kininogen were elevated. In vitro studies suggested that streptococcal supernatants can activate prekallikrein, in addition to causing plasminogen activation through the action of streptokinase.

CONCLUSIONS

Prolongation of activated partial thromboplastin time in streptococcal toxic shock syndrome is associated with activation of the contact system, possibly contributing to the profound shock associated with streptococcal toxic shock syndrome.

Role of streptolysin O in a mouse model of invasive group A streptococcal disease

Many of the virulence factors that have been characterized for group A streptococci (GAS) are not expressed in all clinical isolates. One putative virulence factor that is present among most is streptolysin O (Slo), a protein with well-characterized cytolytic activity for many eukaryotic cells types. In other bacterial pathogens, proteins homologous to Slo have been shown to be essential for virulence, but the role of Slo in GAS had not been previously examined. To investigate the role of Slo in GAS virulence, we examined both revertible and stable slo mutants in a mouse model of invasive disease. When the revertible slo mutant was used to infect mice, the reversion frequency of bacteria isolated from the wounds and spleens of infected animals was more than 100 times that of the inoculum, indicating that there was selective pressure in the animal for Slo(+) GAS. Experiments with the stable slo mutant demonstrated that Slo was not necessary for the formation of necrotic lesions, nor was it necessary for escape from the lesion to cause disseminated infection. Bacteria were present in the spleens of 50% of the mice that survived infection with the stable slo mutant, indicating that dissemination of Slo(-) GAS does not always cause disease. Finally, mice infected with the stable slo mutant exhibited a significant decrease in mortality rates compared to mice infected with wild-type GAS (P < 0.05), indicating that Slo plays an important role in GAS virulence.

Inverse relation between disease severity and expression of the streptococcal cysteine protease, SpeB, among clonal M1T1 isolates recovered from invasive group A streptococcal infection cases

The streptococcal cysteine protease (SpeB) is one of the major virulence factors produced by group A streptococci (GAS). In this study we investigated if differences exist in SpeB production by clonally related M1T1 clinical isolates derived from patients with invasive infections. Twenty-nine of these isolates were from nonsevere cases and 48 were from severe cases, including streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis (NF) cases. The expression and amount of the 28-kDa SpeB protein produced were determined by quantitative Western blotting, and protease activity was measured by a fluorescent enzymatic assay. A high degree of variation in SpeB expression was seen among the isolates, and this variation seemed to correlate with the severity and/or clinical manifestation of the invasive infection. The mean amount of 28-kDa SpeB protein and cysteine protease activity produced by isolates from nonsevere cases was significantly higher than that from STSS cases (P = 0.001). This difference was partly due to the fact that 41% of STSS isolates produced little or no SpeB compared to only 14% of isolates recovered in nonsevere cases. Moreover, the cysteine protease activity among those isolates that expressed SpeB was significantly lower for STSS isolates than for isolates from nonsevere cases (P = 0.001). Increased SpeB production was also inversely correlated with intact M protein expression, and inhibition of cysteine protease activity blocked the cleavage of the surface M protein. Together, the data support the existence of both an "on-off" and a posttranslational regulatory mechanism(s) controlling SpeB production, and they suggest that isolates with the speB gene in the "off" state are more likely to spare the surface M protein and to be isolated from cases of severe rather than nonsevere invasive infection. These findings may have important implications for the role of SpeB in host-pathogen interactions via regulation of the expression of GAS virulence genes and the severity of invasive disease.

Host variation in cytokine responses to superantigens determine the severity of invasive group A streptococcal infection

Cytokines elicited by superantigens have been suggested to play a central role in severe systemic clinical manifestations of gram-positive sepsis. Here we provide evidence for a potent inflammatory cytokine response in acute invasive group A streptococcal infections, and show a direct correlation between the magnitude of this response and the severity of systemic manifestations of the disease. Severe invasive cases suffering from toxic shock and/or necrotizing fasciitis had significantly higher frequencies of IL-2-, IL-6-, and TNF-alpha-producing cells in their circulation as compared to non-severe invasive cases (p=0.05-0.01). This difference was even more accentuated when severe and non-severe cases infected with a clonal M1T1 strain were compared (p=0.03-0. 004). To determine whether host factors were responsible for this difference in magnitude of cytokine responses, paired age- and gender-matched severe and non-severe M1T1 cases (n=8) were tested in vitro during their convalescent phase for immune response to superantigens produced by their infecting isolate. The results showed persistent and inherent differences in the magnitude of proliferative and cytokine responses of severe and non-severe patients to the streptococcal superantigens to which they had been exposed during infection. Thus, the study provides evidence that patients with a propensity to produce higher levels of inflammatory cytokines in response to streptococcal superantigens develop significantly more severe systemic manifestations than patients who have a propensity to produce lower levels of inflammatory cytokines to the same superantigens. We therefore conclude that host factors influence the magnitude of cytokine responses to superantigens and consequently the clinical outcome of the infection.

Skin infections and infestations in Aboriginal communities in northern Australia

The most important skin infections in Aboriginal communities in central and northern Australia are scabies and streptococcal pyoderma. Scabies is endemic in many remote Aboriginal communities, with prevalences in children up to 50%. The cycles of scabies transmission underlie much of the pyoderma. Up to 70% of children have skin sores, with group A streptococcus (GAS) the major pathogen. Group A streptococcus is responsible for the continuing outbreaks of post-streptococcal glomerulonephritis and acute rheumatic fever (ARF). The cycles of scabies transmission in dogs and humans do not appear to significantly overlap. Guidelines have been developed for community control of scabies and skin sores and successful community initiated coordinated programmes have occurred. The anthropophilic dermatophyte Trichophyton rubrum is ubiquitous in many communities, again reflecting living conditions. Other skin infections related to the tropical environment include melioidosis, nocardiosis, Chromobacterium violaceum and chromoblastomycosis. Sustainable and long-term improvements in scabies, skin sores and GAS-related disease and tinea require fundamental changes that address social and economic inequities and, in particular, living conditions and overcrowding.

Clindamycin in the treatment of streptococcal and staphylococcal toxic shock syndromes

OBJECTIVE

To evaluate the utility of clindamycin in the treatment of streptococcal and staphylococcal toxic shock syndromes.

DATA SOURCES

Biomedical literature was accessed through MEDLINE (1966-December 1999). Key terms included clindamycin, streptococcal toxic shock, and staphylococcal toxic shock.

DATA SYNTHESIS

Streptococcal and staphylococcal toxic shock syndromes are associated with a high mortality rate. beta-Lactams have been considered the drug of choice for the treatment of these serious infections, with the occasional use of adjunctive clindamycin, although no clinical evidence has been published to support this latter regimen. An evaluation of the information to propose the usefulness of clindamycin was conducted.

CONCLUSIONS

Experimental laboratory evidence suggests utility of the adjunctive use of clindamycin in streptococcal and staphylococcal infections complicated by toxin production. Research using animal models comparing clindamycin plus beta-lactams with beta-lactams alone for the treatment of these infections would be useful.

Streptococcal toxic shock syndrome associated with necrotizing fasciitis

Streptococcal toxic shock syndrome (strep TSS) with associated necrotizing fasciitis is a rapidly progressive process that kills 30-60% of patients in 72-96 h. Violaceous bullae, hypotension, fever, and evidence of organ failure are late clinical manifestations. Thus, the challenge to clinicians is to make an early diagnosis and to intervene with aggressive fluid replacement, emergent surgical debridement, and general supportive measures. Superantigens such as pyrogenic exotoxin A interact with monocytes and T lymphocytes in unique ways, resulting in T-cell proliferation and watershed production of monokines (e.g. tumor necrosis factor alpha, interleukin 1, interleukin 6), and lymphokines (e.g. tumor necrosis factor beta, interleukin 2, and gamma-interferon). Penicillin, though efficacious in mild Streptococcus pyogenes infection, is less effective in severe infections because of its short postantibiotic effect, inoculum effect, and reduced activity against stationary-phase organisms. Emerging treatments for strep TSS include clindamycin and intravenous gamma-globulin.

Analysis of plasminogen-binding M proteins of Streptococcus pyogenes

Group A streptococci are common human pathogens that cause a variety of infections. They express M proteins which are important cell wall-bound type-specific virulence factors. We have found that a set of strains, associated primarily with skin infections, express M proteins that bind plasminogen and plasmin with high affinity. The binding is mediated by a 13-amino-acid internal repeated sequence located in the N-terminal surface-exposed portion of these M proteins. This sequence binds to kringle 2 in plasminogen, a domain that is not involved in the interaction with streptokinase, a potent group A streptococcal activator of plasminogen. It could be demonstrated that plasminogen, absorbed from plasma by growing group A streptococci expressing the plasminogen-binding M proteins, could be activated by exogenous and endogenous streptokinase, thereby providing the bacteria with a surface-associated enzyme that could act on the tissue barriers in the infected host.

Genetic relatedness and superantigen expression in group A streptococcus serotype M1 isolates from patients with severe and nonsevere invasive diseases

The relatedness of group A streptococcal (GAS) strains isolated from 35 Canadian patients with invasive disease of different severity was investigated by a variety of molecular methods. All patients were infected with M1T1 strains and, based on clinical criteria, were classified as severe (n = 21) and nonsevere (n = 14) invasive GAS infection cases. All the M1 strains studied had the emm1.0 allele and the same streptococcal pyrogenic exotoxin (Spe) genotype, speA(+) speB(+) speC speF(+) speG(+) speH smeZ(+) ssa. All isolates had the same speA allotype, speA2. The randomly amplified polymorphic DNA banding pattern with two different primers was identical for all strains, and pulsed field gel electrophoresis analysis showed that 33 and 30 isolates had identical banding patterns after DNA digestion with SfiI or SmaI, respectively; the nonidentical isolates differed from the main pattern by only one band. A relatively high degree of polymorphism in specific regions of the sic gene was observed among isolates; however, this polymorphism was not associated with disease severity. Likewise, although the phenotypic expression of SpeA, SpeB, and SpeF proteins varied among the M1T1 isolates, there was no correlation between the amount of Spe expressed and disease severity. Importantly, mitogenic and cytokine responses induced by partially purified bacterial culture supernatants containing a mixture of expressed superantigens were very similar for isolates from severe and nonsevere cases (P > 0.1). Together, the data indicate that highly related invasive M1T1 isolates, some indistinguishable, can cause disease of varying severity in different individuals. These findings underscore the contribution of host factors to the outcome of invasive GAS infections.

A boy with erosive arthritis during treatment of severe group-A streptococcal infection

Abstract The patient was admitted to our department with major complaints of fever, swelling of the left thigh, and a cognition disorder. A blood culture yielded type T1, toxin-B-positive group-A streptococcus. Magnetic resonance imaging of the left foot showed fasciitis. Severe group-A streptococcal infection was diagnosed, and the administration of antibiotics, a massive dosage of gamma-globulin, and a steroid preparation were prescribed, which resulted in a general improvement in the symptoms and reductions in the swelling of the left foot and the second finger of the left hand without any sequelae. Following discharge from the hospital, however, destruction of the joint of the first toe of the right foot was recognized. A number of cases of post-streptococcal reactive arthritis (PSRA) have recently been reported, and the pathogenicity of this arthritis, which is different from that of rheumatic fever, has been noted. Severe group-A streptococcal infections, such as the one described here, may develop into erosive arthritis after the symptoms, that affect several organs, have disappeared. We believe that because it is possible for post-streptococcal reactive arthritis to develop, one should be aware of this when dealing with all clinical patients who have streptococcal infections.

Streptoccocus pyogenes: a forgotten cause of severe community-acquired pneumonia

We report a case of severe community-acquired pneumonia caused by Streptococcus pyogenes (Lancefield Group A streptoccocus) that was complicated by a streptococcal toxic shock syndrome. Although this micro-organism is an uncommon cause of community-acquired pneumonia, previously well individuals may be infected and the clinical course may be fulminant. A household contact was the likely point of infection. Invasive group A streptococcal disease continues to remain an important cause of morbidity and mortality in the community and therefore will continue to be encountered by intensive care physicians. Treatment of Group A streptococcal infection remains penicillin; however, clindamycin should be added in severe infection.

Macrolide resistance and erythromycin resistance determinants among Belgian Streptococcus pyogenes and Streptococcus pneumoniae isolates

Resistance of streptococci to macrolide antibiotics is caused by target-site modification or drug efflux. The phenotypic expression of target-site modification can be inducible or constitutive. The prevalence of the three phenotypes among Belgian erythromycin-resistant Group A streptococci (GAS) and Streptococcus pneumoniae isolates was surveyed, their MICs for seven antibiotics were determined and the clonality of the isolates was explored. Of the 2014 GAS isolates tested 131(6.5%) were erythromycin resistant (MIC > 1 mg/L): 110 (84.0%) showed the M-resistance phenotype whereas the remaining 21 strains (16.0%) were constitutively resistant. No inducibly resistant strains were detected. Of 100 S. pneumoniae isolates, 33 were erythromycin resistant (MIC > 1 mg/L). In contrast to the GAS isolates, only 9.1% of the 33 erythromycin-resistant S. pneumoniae isolates showed the M-resistance phenotype. The presence of mefA/E and ermB genes in the M-resistant and constitutively and inducibly resistant strains, respectively, was confirmed by PCR analysis. Genomic analysis based on pulsed-field gel electrophoresis (PFGE) using the restriction enzyme SfiI, revealed 54 different PFGE patterns among the 131 erythromycin-resistant GAS isolates, of which an M6 clone represented 16.0% of the strains; all other clones, exhibiting different M-types, represented <7% of the strains. The S. pneumoniae isolates also appeared to be polyclonally based, as determined by arbitrarily primed PCR. The macrolides miocamycin and rovamycin, the lincosamide clindamycin and the ketolide HMR 3647 showed excellent activity against the M-resistant GAS and S. pneumoniae strains.

Characteristics of Streptococcus pyogenes serotype M1 and M3 isolates from patients in Japan from 1981 to 1997

Streptococcus pyogenes isolates obtained in 1981 to 1997 from patients and healthy subjects were characterized by pulsed-field gel electrophoresis (PFGE) patterns, biotyping, and the presence of spe genes encoding streptococcal pyrogenic exotoxins. Changes in the profiles were shown in the serotype M1/T1 isolates from pharyngitis over this period, but not in serotype M3/T3 isolates. The characteristics of isolates from patients with toxic shock-like syndrome (TSLS) were comparable to those of the other isolates, including those from healthy subjects. This finding suggests that further phenotypic and molecular characterization, such as investigating the genomic difference represented by the pathogenicity island, of isolates with apparently the same profiles would be necessary to determine the etiology of diseases caused by S. pyogenes, including TSLS.

Post-varicella epiglottitis and necrotizing fasciitis

Varicella is a nearly ubiquitous acquired childhood disease. Infectious complications of varicella can be life- or limb-threatening. These complications appear 3 to 4 days after the appearance of varicella exanthem and are heralded by fever, pain, and erythema of the overlying skin. Airway complications of varicella are rare, rapidly evolving, and, unfortunately, difficult to visualize. We report a child who presented with a unique combination of varicella-induced airway complications-acute epiglottitis and subsequent necrotizing fasciitis of the head and neck. varicella, epiglottitis, necrotizing fasciitis, group A beta-hemolytic streptococcus, nasopharyngoscopy.

Outbreak among drug users caused by a clonal strain of group A streptococcus

We describe an outbreak among drug users of severe soft-tissue infections caused by a clonal strain of group A streptococcus of M-type 25. Cases (n = 19) in drug users were defined as infections (mainly needle abscesses) due to the outbreak strain. Comparison with controls showed that infected drug users bought drugs more often at a specific place. Drug purchase and use habits may have contributed to this outbreak.

Bacterial and protozoal infections

The oral cavity is a common site for manifestations of systemic microbial diseases. Oral lesions may be typical of those seen elsewhere on the body, or the lesions may be modified by the local environment. The ease of examination within the oral cavity, however, and any site-specific features facilitates diagnosis of the systemic condition.