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PubMed1984

Biotyping and exoenzyme profiling as an aid in the differentiation of human from bovine group G streptococci.

Group G streptococci were isolated from throat and extrapharyngeal cultures from 75 patients during an 18-month period. Of 29 throat isolates, 18 were recovered from patients with pharyngitis, 8 were of unknown significance, and 3 were of questionable etiology. Clinical significance could be ascribed to 13 of 46 extrapharyngeal isolates recovered from wound, urinary tract, blood, and conjunctival cultures. Extrapharyngeal isolates recovered from stool, sputum, and vaginal cultures were considered nonsignificant. A total of 96 group G streptococcal strains (including 21 human and 14 bovine strains from outside sources) were tested for exoenzyme production and subjected to a large battery of biochemical tests. Bovine and human isolates could be distinguished on the basis of trehalose fermentation, litmus milk reduction, and production of beta-D-glucuronidase, hyaluronidase, and fibrinolysin. Eight distinct biotypes could be discerned on the basis of fermentation of trehalose, raffinose, and lactose and esculin hydrolysis. All isolates that fermented raffinose were associated with infection. These results support the concept of two distinctly different epidemiological reservoirs of group G streptococci in humans and bovines.

Animals↗

PubMedDate not supplied

Clinical features and antimicrobial therapy of infections caused by group G streptococci.

Group G streptococci were isolated from various clinical sites in 64 patients hospitalized between 1979 and 1983. Oropharyngeal and wound infections occurred most commonly, although some of these isolates represented colonization. Ten patients had serious infections including five with endocarditis. Patients with endocarditis tended to be older, had underlying conditions predisposing them to infection, and responded poorly to single agent therapy with penicillin G or other beta-lactam agents, despite exquisite in vitro susceptibility. Patients with serious infections but without endocarditis tended to be younger, had fewer underlying disorders and responded rapidly to therapy with beta-lactam antibiotics. All isolates were susceptible to penicillin G, cephalothin, vancomycin and newer beta-lactam agents. Occasional tolerance was observed. Combinations of penicillin G with an aminoglycoside and of vancomycin with an aminoglycoside or rifampin were bactericidal against the tolerant strains. Although none of the organisms isolated from patients with endocarditis were tolerant, this infection should be treated with combination antibiotic therapy.

Adult↗

PubMedDate not supplied

[Macrolide resistance phenotypes and genotypes in group G streptococci].

Group G streptococci (GGS) are among the bacterial causes of pharyngitis. In this study, a total of 57 GGS strains isolated from throat swabs were initially screened by NCCLS disk diffusion test for penicillin and erythromycin susceptibilities. Phenotypes of the erythromycin resistance were determined by a triple-disk test and the responsible genes were sought by polymerase chain reaction (PCR) using mefA, ermA, ermA-subclass ermTR and ermB primer sets. Erythromycin and clindamycin minimal inhibitory concentrations (MIC) of the resistant isolates were measured by NCCLS agar dilution method, while susceptibility rates to some other antibiotics were determined by the disk diffusion test. All isolates were found susceptible to penicillin, and 8 (14%) were resistant to erythromycin. Of the resistant isolates, 3 (37.5%) expressed M phenotype and 5 (62.5%) had inducible macrolide-lincosamide-streptogramine B resistance (iMLS). All M isolates had mefA determinant. Of non-M isolates, 3 (37.5%) had subclass ermTR. In 2 (25%) isolates none of the four gene determinants was detected. MIC ranges of erythromycin and clindamycin for M and iMLS phenotypes were 4, 4-128 micrograms/ml and < or = 0.06-0.125, 0.25 - > or = 128 micrograms/ml, respectively. All the erythromycin-resistant isolates were also resistant to tetracycline. The high macrolide-resistance rate of GGS in our hospital deserves attention, however this finding should be confirmed by multi-centre studies including more representative isolates.

Anti-Bacterial Agents↗

PubMed1964

IMMUNOCHEMICAL STUDIES ON THE SPECIFIC CARBOHYDRATE OF GROUP G STREPTOCOCCI.

Group G hemolytic streptococcal cell walls which have been treated with trypsin are composed of a group-specific polysaccharide moiety and a mucopeptide matrix. The mucopeptide contains N-acetylglucosamine, N-acetylmuramic acid, alanine, glutamic acid, lysine, and glycine, a composition similar to that of other groups of streptococci. The Group G carbohydrate is composed of rhamnose, N-acetylgalactosamine, and galactose. Serological studies suggest that the monosaccharide of L-rhamnose is a major component of the determinant of antigenic specificity.

Alanine↗

PubMed1995

M or M-like protein gene polymorphisms in human group G streptococci.

Many group G streptococci (GGS) isolated from infected humans (but not from animal sources) express M or M-like proteins with biological, immunochemical, and genetic features similar to those of group A streptococci (GAS). To further elucidate the recently proposed M-like protein gene (emmL gene) polymorphisms in GGS, Southern blots of genomic DNAs from 38 epidemiologically unrelated GGS strains isolated from human specimens and 12 GGS strains recovered from animal sources were hybridized with oligonucleotide probes designed to specifically detect GAS M class I and M class II M protein (emm) genes. All human-associated GGS strains showed DNA homology to the GAS M class I emm gene probe, whereas no hybridization was found with DNA from any of the animal-associated strains. The emmL genes from all human isolates were amplified by PCR, and the complete sequence of the emmL gene of the Rebecca Lancefield grouping strain D166B was determined. Again, this gene exhibited the structural features typical for emm genes of M class I GAS. The 5' regions of the PCR-amplified emmL genes of the remaining 37 human GGS strains were sequenced. This region showed a sequence diversity similar to that known for GAS emm genes. When strains whose N-terminal emmL gene sequences showed a homology of > 95% were defined as belonging to one genetic type, 30 strains were segregated into six distinct genetic types, whereas the remaining 8 strains each exhibited a unique emmL gene sequence. A high degree of homology between the N-terminal emmL gene segments of six GGS strains and the corresponding regions of either the emm12 or the emm57 gene of GAS was found, suggesting a horizontal gene transfer between strains of these species of beta-hemolytic streptococci. Besides a further understanding of the evolution of GGS emmL genes, the observed emmL gene polymorphisms in GGS could provide the basis for a molecular subspecies delineation of strains and offers the potential of typing GGS for epidemiological purposes.

Amino Acid Sequence↗

PubMed1979

Immunoglobulin-binding structure on bovine group G streptococci different from type III Fc receptors on human group G streptococci.

The immunoglobulin G (IgG)-binding capacity of 54 group G streptococci of human and bovine origin was investigated. Of 20 human strains, 17 carried a surface component which could combine with human IgG and bovine IgG1 and IgG2. Inhibition experiments with unlabeled human IgG and with a panel of animal sera revealed that the same surface component was involved in the binding of human as well as bovine immunoglobulins. Of 16 beta-hemolytic bovine group G streptococci, 13 reacted with human IgG but not with bovine IgG1 or IgG2. This binding structure was different from the type III Fc reactivity found in human group G streptococci. All human strains, including the three IgG Fc-nonreactive strains, fermented trehalose, in contrast to all bovine beta-hemolytic strains, which were negative. Immunoglobulin Fc reactivity is thus a feature not only of human strains but also of some bovine strains.

Animals↗

PubMed1985

Infections due to Lancefield group G streptococci.

The group G streptococcus has surfaced in the past 10 to 15 years as an important opportunistic and nosocomial pathogen. Although more precise organism recognition accounts for a portion of these cases, there can be little doubt that the group G streptococcus has become a more prevalent pathogen. Commercial kits, utilizing staphylococcal coagglutination or latex agglutination, are now available, affording all clinical laboratories the opportunity to identify this organism easily. Published reviews encompassing the experiences of a single institution or even several institutions affiliated with a single medical center, particularly as they were influenced by referral patterns, did not reflect the broad scope of infections that we discovered by extending our survey into the community, beyond the medical center complex and its immediate affiliated hospitals. Although malignancy is the single most obvious background factor, alcoholism and diabetes are also important host determinants of infection. Skin and soft-tissue infections (and surface sources of infection) are equally important among patients with or without the element of malignancy. Polymicrobial infection, including polymicrobial bacteremia, is an important feature, with S. aureus infections accounting for most of these cases, relating to the skin and soft tissue sources of infections so commonly seen. We saw a panorama of problems including endocarditis, septic arthritis, pleuropulmonary infections, bone and joint infections, puerperal sepsis and neonatal infection, peritonitis and ophthalmitis; we also saw a significant number of patients with bacteremia and no apparent primary source of infection. Response to antibiotic therapy was dictated by the nature of the underlying diseases, and individuals without a background of malignant disease did well, particularly those with skin and soft-tissue infections. While the literature suggests that patients with endocarditis and septic arthritis due to this organism respond poorly to antibiotic therapy, implying that such failures relate to in vitro antibiotic phenomena, we preferred to examine the problem from the viewpoint of the host(s) involved. Subacute endocarditis and acute endocarditis due to the group G streptococcus may be clinically separable, and thus require separate therapeutic approaches. In patients with septic arthritis, prosthetic devices, prior joint disease and immunosuppressive diseases and therapy often adversely influence the response to antibiotic therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Abortion, Septic↗

PubMed1987

Biological and immunochemical identity of M protein on group G streptococci with M protein on group A streptococci.

Previous evidence for the presence of an M or M-like protein on group G streptococci has been based on the ability of these strains to survive in human blood. In addition, cross-reactions between group A and group G streptococci have been demonstrated, but they have relied either on whole bacterial cell vaccine-induced polyclonal sera or crude protein extracts of these cells. In this study two monoclonal antibodies prepared against the purified, native group A streptococcal M6 protein demonstrated a high degree of cross-reactivity with group G streptococcal clinical isolates (9 and 19 of 22 strains examined, respectively). Ten of these strains exhibited resistance to phagocytosis when rotated in human blood. In addition, immunoblot analysis of crude mutanolysin extracts of group G streptococci with one of the M6 monoclonal antibodies illustrated a remarkable similarity in the protein pattern of these extracts as compared with those of group A streptococcal M protein. The immunoblots further demonstrated a variation in the relative molecular weights of the extracted proteins from strain to strain over a range of 57,000 to 77,000. In addition, a purified, pepsin-derived fragment (Mr, 43,000) from a group G strain was capable of eliciting rabbit antibodies that were opsonic for group G cells in a bactericidal assay. These functional and immunochemical data, in concert with DNA hybridization between group G streptococcal DNA and a group A M6 gene probe (J. R. Scott, W. M. Pulliam, S. K. Hollingshead, and V. A. Fischetti, Proc. Natl. Acad. Sci. USA 82:1822-1826, 1985), provide strong evidence for the presence of an M protein on these organisms and indicate its probable role as a virulence molecule on the surface of group G streptococci.

Antibodies, Bacterial↗

PubMed1995

M proteins of group G streptococci: mechanisms of resistance to phagocytosis.

Group G streptococci that express M protein and resist phagocytosis in human blood (virulent strains) were compared with strains of groups G and A that are readily phagocytosed (avirulent). Virulent group G streptococci were less effective (P < .05) as activators of the alternative complement pathway (ACP) than were avirulent streptococci. In immunofluorescence studies, C3 bound more avidly to avirulent than to virulent group G streptococci. Resistance of virulent group G strains to ACP opsonization and to phagocytosis was markedly diminished by removal with pepsin of the type-specific portion of the M molecule. Preincubation with fibrinogen did not diminish ACP activation or C3 binding by virulent group G and A streptococci but did exert an antiphagocytic effect. Given the similarity of M proteins of groups G and A in structure and function, other microbial constituents are likely responsible for differences in the spectra of illnesses attributable to the two serogroups.

Antigens, Bacterial↗

PubMed1988

LY146032 compared with penicillin G in experimental aortic valve endocarditis caused by group G streptococci.

Rabbits with group G streptococcal aortic endocarditis received no therapy (controls); repeated doses of procaine penicillin G, 300 mg/kg (body weight) per day, administered intramuscularly; or LY146032, a new peptolide antibiotic, 20 mg/kg per day, administered intravenously. Penicillin G and LY146032 reduced mean intravegetation group G streptococcal densities significantly below those observed in controls at both day 3 and day 6 of therapy. Penicillin G effected a more rapid clearance of intravegetation streptococci than LY146032 by day 3, but not by day 6, of therapy.

Animals↗

PubMed1982

Group G streptococci: a review of the literature.

A review of the occurrence, general characteristics, and identification procedures for Group G streptococci is presented. Group G streptococci cause the same types of infection and have similar morphological characteristics as the other beta-hemolytic streptococci. If serological methods are used for identification, cross reactions may be seen between Group G and B streptococci, as they share a common antigenic determinant. Group G may also be misidentified as Group A streptococci with biochemical testing because at least 7% of Group G are sensitive to bacitracin. are sensitive to bacitracin. are sensitive to bacitracin.

Humans↗

PubMed1992

Differentiation of species in human beta-haemolytic group G streptococci using immunoglobulin Fc fragment receptor.

AIMS: To assess the ability of human immunoglobulin Fc fragment binding activity to differentiate human biotype large colony group G streptococci from the group G "Streptococcus milleri group". METHODS: Fifty two isolates of large colony group G streptococci and 30 group G "S milleri group" strains were tested for their ability to bind fluorescein conjugated human IgG Fc fragments after acetone fixation. Immunoblotting with peroxidase labelled human Fc fragments after resolution of bacterial polypeptides by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed for six large colony strains. RESULTS: All large colony group G streptococci showed positive Fc fragment binding whereas all "S milleri group" bacteria failed to bind Fc fragments when viewed by fluorescence microscopy. All six large colony strains showed similar immunoblot binding patterns. CONCLUSION: Immunoglobulin Fc fragment receptor content distinguishes the large colony group G streptococci from the group G "S milleri group" and mayhave a role in the rapid laboratory diagnosis of pharyngeal pathogens.

Child↗

PubMed1991

Biochemical properties of group G streptococci isolated from cats and man.

The biochemical characteristics of group G streptococci isolated from cats were markedly similar to the characteristics of group G streptococci from man. Both cat and human isolates of group G streptococci were also very similar in biochemical characteristics to group A streptococci so that to identify the source of group G streptococci by biochemical reactions is not a reliable procedure. The group G streptococci found in many cats could be pathogenic to man, since their physiological and biological characteristics are very similar to those of group A streptococci.

Aminopeptidases↗

PubMed1991

Comparison of albumin receptors expressed on bovine and human group G streptococci.

The albumin receptor expressed by bovine group G streptococci was extracted and affinity purified. The protein was characterized for species reactivity, and monospecific antibodies were prepared to the purified receptor. The bovine group G albumin receptor was compared functionally, antigenically, and for DNA homology with the albumin-binding protein expressed by human group G streptococci. In agreement with previous reports, the albumin-binding activity of human strains was mediated by a unique domain of the type III immunoglobulin G-Fc-binding molecule, protein G. The albumin receptor expressed by bovine group G strains was found to lack any immunoglobulin G-binding potential but displayed a wider profile of species albumin reactivity than protein G. Both albumin receptors could inhibit the binding of the other to immobilized human serum albumin, and each displayed similar binding properties. Antigenic comparison of the two albumin receptors demonstrated a low level of cross-reactivity; however comparison at the DNA level, using an oligonucleotide probe specific for the albumin-binding region of protein G, demonstrated that the two albumin receptors expressed by human and bovine group G streptococcal strains do not display significant homology.

Albumins↗

PubMed1986

A new scheme for serotyping group-G streptococci.

Ten antisera, prepared against nine selected strains of group-G streptococci and a strain of group-A streptococci of M-type 12, were used to serotype 102 isolates of group-G streptococci by means of precipitation reactions between the sera and hot-acid extracts of the streptococci. Fifty-six (54.9%) of the streptococci could be typed; eight serotypes were identified, of which type VIII was the most common (18.6%). The M12 and the R28 antigens, previously recorded in group-G streptococci, were not detected. The type antigens were trypsin sensitive and resembled the M antigens of group-A streptococci.

Animals↗

PubMed1986

Group C and group G streptococci. In-office isolation from children and adolescents with pharyngitis.

The importance of non-group A streptococci as etiologic agents of acute pharyngitis in endemic circumstances is unclear. The authors attempted to clarify this issue in patients undergoing throat culture for acute pharyngitis in a suburban pediatric practice. Of 6,694 throat cultures, 2,243 (34%) yielded B-hemolytic streptococci, 83 percent (1,783) of which were bacitracin-sensitive and presumptive group A organisms. A random selection of 279 of the 460 bacitracin-resistant streptococci yielded 56 group C, 42 group G, 35 group F, 2 group A, and 3 mixed groups of streptococci. Paired serologic specimens were obtained from 12 children with group C or G streptococci. Four of six group C subjects from whom paired serum specimens were obtained had a significant increase in anti-streptolysin O titer. However, no change in anti-C/G hyaluronidase or anti-C carbohydrate titer was observed. Similarly, two of six subjects with group G streptococci on throat culture in whom paired serum specimens were obtained showed an increase in ASO titer. No seroconversion to anti-C/G hyaluronidase, anti-C, or anti-G carbohydrates was demonstrated. Despite substantial clinical and circumstantial evidence, it could not be confirmed serologically that group C and G streptococci produced acute pharyngitis in this endemic setting.

Adolescent↗

PubMed1987

M proteins of group G streptococci isolated from bacteremic human infections.

We studied seven strains of group G streptococci isolated from clinically severe bacteremic infections in six intravenous drug abusers. These group G strains multiplied luxuriantly in fresh human blood. On electron microscopy, they exhibited surface fibrillae similar to those observed in M-protein-rich group A streptococci, but they were not serologically M typable with a battery of 39 M antisera. Rabbit antisera raised against two of the group G strains (1618 and 1750) opsonized the homologous but not the heterologous isolates and exhibited type-specific Ouchterlony immunoprecipitin reactions. Moreover, antisera raised against peptic extracts of strain 1750 also promoted phagocytic killing of that strain. Anti-1750 reacted in high titer in an enzyme-linked immunosorbent assay against peptic extracts of the homologous strain; these antibodies were removed by absorption with 1750 cells but not by absorption with heterologous strains. These studies represent, to our knowledge, the first analysis of virulence factors of group G streptococci isolated from invasive human disease. The seven epidemiologically related blood isolates of group G streptococci possess distinct type-specific, antiphagocytic surface virulence factors analogous to the M proteins of group A streptococci.

Antibodies, Bacterial↗

PubMed1980

Neonatal sepsis due to group G streptococci.

Two cases of neonatal septicaemia due to group G streptococci (Streptococcus canis) are described. In one patient, infection coexisted with transient neonatal hyperthyroidism, while, in the other, concomitant group G streptococcal septicaemia and endometritis in the mother was seen. Group G streptococci are rare causes of infection, especially in the paediatric age group. Bacteria were identified by serological and biochemical methods. Both neonates responded well to penicillin therapy, but the maternal infection required combination therapy with penicillin G, gentamicin, and chloramphenicol. The literature on systemic group G streptococcal infection is briefly reviewed. With increasing use of serotyping in the identification of beta-haemolytic streptococci, non-group A organisms will probably be identified more frequently from neonatal and other infections.

Adolescent↗