PubMed Health⌕ Search

Biomedical subjects

I W Wibawan

Publications and source records attributed to I W Wibawan.

At least 19 recordsLinked to original sources
PubMed1999

The role of hyaluronic acid capsular material of Streptococcus equi subsp. zooepidemicus in mediating adherence to HeLa cells and in resisting phagocytosis.

Hyaluronic acid is thought to be one of the critical virulence factors of Streptococcus equi subsp. zooepidemicus. The present study was designed to study the role of hyaluronic acid capsular material in mediating adherence and to resist the phagocytosis of the host's immune defence. The studies were performed with two encapsulated S. equi subsp. zooepidemicus and two unencapsulated phase variants. The bacteria had been previously isolated from diseased pigs and monkeys in Indonesia. The presence of capsular material was determined using the hyaluronic acid decapsulation test and by electron microscopic studies. Both encapsulated bacteria showed mucoid colonies after cultivation on blood agar, grew with diffuse colonies in soft agar media and reacted negatively in the salt aggregation test. The unencapsulated bacteria grew with small colonies on blood agar, formed compact colonies in soft agar media and reacted positively in the salt aggregation test. Adherence and phagocytosis studies revealed that the encapsulated bacteria adhered significantly more to HeLa cells and were less phagocytosed by murine macrophages compared to unencapsulated bacteria. Pretreatment of the HeLa cells using hyaluronic acid or pretreatment of the bacteria by hyaluronidase decreased the adherence value of encapsulated bacteria. Pretreatment of bacteria with pronase had no effect. The presented results strongly indicate that the hyaluronic acid capsular material contributes to adherence properties of S. equi subsp. zooepidemicus and might help the bacteria to resist phagocytosis by macrophages.

Animals↗
PubMed1996

Identification and molecular characterization of serological group C streptococci isolated from diseased pigs and monkeys in Indonesia.

The present study was designed to comparatively investigate 34 beta-hemolytic streptococci isolated from infected pigs and monkeys from various islands in Indonesia. According to the serological and biochemical data, all 34 isolates were Lancefield's serological group C streptococci and could be identified as Streptococcus equi subsp. zooepidemicus. Of the 34 group C streptococci investigated, 28 grew on solid media in large, mucoid colonies, in fluid media at a uniform turbidity, and in soft agar in diffuse colonies. A decapsulation test with a hyaluronidase-producing Staphylococcus aureus strain revealed the hyaluronic acid nature of the capsular material. The remaining six streptococci grew on solid media in small, nonmucoid colonies, in fluid media as sediment with clear supernatant, and in soft agar in compact colonies. Determination of surface hydrophobicity by salt aggregation revealed a hydrophilic surface for the encapsulated bacteria and a hydrophobic surface for the unencapsulated group C streptococci. To further analyze the epidemiological relationships, all 34 mucoid and nonmucoid isolates from pigs and monkeys were subjected to protein and DNA fingerprinting. The latter was performed by pulsed-field gel electrophoresis. The protein profiles of all 34 isolates and the DNA profiles of 32 isolates appeared to be identical, with the DNA profiles of 2 isolates being closely related, indicating that a single virulent clone is responsible for this disease outbreak in Indonesia.

Animals↗
PubMed1995

Comparison of streptococci of serological group B isolated from healthy carriers and active disease in Chile.

Serotyping of 50 streptococcal strains of serological group B isolated from human clinical specimens in Chile revealed mainly the serotypes Ia, II and III, either alone or in combination with protein antigens c or R. No significant difference in serotype distribution was detected between group B streptococci isolated from cervical swabs from clinically healthy women and those isolated from various pathological processes. Determination of antibiotic susceptibility of the bacteria demonstrated resistance to tetracycline and minocycline in 29 isolates. All 29 tetracycline-resistant cultures hybridised with a gene probe for tet(M). Again, no differences were detected between the group B streptococcal isolates of various origins.

Blotting, Southern↗
PubMed1994

Distribution of genes conferring combined resistance to tetracycline and minocycline among group B streptococcal isolates from humans and various animals.

Forty-nine tetracycline and minocycline resistant streptococci of serological group B isolated from humans, cattle, pigs and nutrias were investigated for the presence of genes conferring this combined resistance. Southern blot hybridization of EcoRI-digested chromosomal DNA of the bacteria revealed for 39 of the cultures a hybridization signal with tet(M), for four of the cultures a hybridization signal with tet(O) and for none of the cultures a hybridization signal with the tet(Q) gene probe. The restriction endonuclease digested and blotted DNA of six tetracycline and minocycline resistant group B streptococci did not hybridize with any of the available gene probes. The tet(M) gene probes recognized complementary sequences of EcoRI fragments of approximately 10.5 kb and 21.5 kb, the tet(O) gene probe hybridized with fragments of approximately 19 kb. The hybridization of the tet(M) gene probe in two different patterns appeared to be related to the origin of the cultures.

Animals↗
PubMed1994

Relation between encapsulation and various properties of Streptococcus suis.

Encapsulation is thought to be a critical virulence factor for Streptococcus suis. In this study, encapsulation of a selected S. suis culture could be stimulated by cultivation conditions. After cultivation of the S. suis culture in fluid media supplemented with serum, the culture grew with short chains and a uniform turbidity of the growth medium. Autoclave extracts of this culture reacted with capsular type-1-specific antiserum. After cultivation of the S. suis culture in fluid media without serum, the bacteria generally formed longer chains, grew in fluid medium as granular sediment with clear supernatant, and were non-typeable. In addition, the unencapsulated variant appeared to have a more hydrophobic surface and adhered significantly more to HeLa cells. In contrast to the unencapsulated variant, the encapsulated S. suis was phagocytosed to a lesser extent by polymorphonuclear leucocytes. These findings might help to elucidate the role of encapsulation in infections with this bacterial organism.

Animals↗
PubMed1994

Phase variation in streptococci of serological group B. Characteristic properties of isolates from human and bovine infection.

Encapsulation is thought to be a critical virulence factor in streptococci of serological group B. In the present study two encapsulated low-density variants could be separated from their unencapsulated original strains by Percoll gradient centrifugation. The original strains had been isolated from human endocarditis and bovine mastitis. Type antigen preparations of the encapsulated human and bovine group B streptococcus reacted with type III- and type IV-specific antiserum, respectively. No comparable reactions could be observed with their unencapsulated parent strains. In contrast to the original strains, the encapsulated variants grew with uniform turbidity in fluid medium and formed diffuse colonies in soft agar. The original strains grew as granular sediment and formed compact colonies in soft agar. In addition, the original strains appeared to have a more hydrophobic surface and showed significantly greater adherence to epithelial cells. In contrast to the nonencapsulated parent strains, the encapsulated variants were less phagocytosed by polymorphonuclear leukocytes. These findings may help our understanding of the pathogenic importance of phase variants in infections with this bacterial organism.

Animals↗
PubMed1993

A haemagglutinating adhesin of group B streptococci isolated from cases of bovine mastitis mediates adherence to HeLa cells.

Rabbit erythrocytes were agglutinated by 43.4% of group B streptococci isolated from bovines but by none isolated from humans. Haemagglutination was enhanced by cultivation of the bacteria under microaerophilic conditions. Most of the haemagglutinating strains had protein type antigen X, either alone, or in combination with polysaccharide antigens. Heat and proteolytic treatment of the bacteria destroyed the haemagglutination activity. The haemagglutinin could be solubilized from the bacterial surface by mutanolysin treatment and isolated from culture supernatant fluid by ammonium sulphate precipitation. The isolated haemagglutinin did not cause direct agglutination of erythrocytes. However, binding of the haemagglutinin to rabbit erythrocytes could be visualized by agglutination of haemagglutinin-treated erythrocytes by specific antiserum obtained by absorption. Western blotting showed that the haemagglutinin obtained from erythrocyte lysates contained an antibody-reactive band with a molecular mass of 43 kDa. Haemagglutination-positive strains adhered to HeLa cells in higher numbers than did haemagglutination-negative strains. The HeLa cell adherence of Group B streptococci was inhibited in the presence of isolated haemagglutinin or of specific antiserum against the haemagglutinin. These observations suggest that the haemagglutinating adhesins of bovine group B streptococcal isolates are directly involved in the adherence mechanisms of these organisms.

Adhesins, Bacterial↗
PubMed1993

Relation between serotype of streptococci of serological group B and growth rate at early logarithmic phase.

Determination of growth rate of streptococci of serological group B at early logarithmic phase by measuring optical density of the growth medium and by measuring the change of conductivity of the culture fluid appeared to be closely related to the serotype of the respective cultures. Most of the human and bovine group B streptococci with type patterns Ia/c, II, III and IV exhibited clearly visible growth of the culture medium after 4 h incubation and changed the conductivity of the culture fluid to a point defined as time to detection within 4 h. No comparable growth could be observed with most of the cultures possessing type antigens R and X, either alone, or in combination with polysaccharide antigens. The importance of type specific capsule sialylation to the growth rate of the bacteria could be additionally shown with two group B streptococci of serotype III and their transposon mutagenized asialo capsular mutants. Both sialylated wild-type group B streptococci grew much quicker than their asialo capsular mutants. The results from additional experiments revealed that the growth velocity seemed to be significantly related to the chain length of the bacteria, to growth patterns of the group B streptococci in fluid media and soft agar and to the surface hydrophobicity of the bacteria. Determination of growth rate at early logarithmic phase could be used to predict various degrees of capsular sialylation of group B streptococci. This might help to understand the pathogenicity of individual group B streptococcal isolates in clinical cases.

Animals↗
PubMed1993

Properties and type antigen patterns of group B streptococcal isolates from pigs and nutrias.

All 59 group B streptococcal cultures isolated from pigs and nutrias reacted with group B-specific antiserum and gave a positive CAMP reaction in the zone of staphylococcal beta-lysin. Most of the cultures were pigmented; all cultures hydrolyzed Na hippurate and utilized salicin, maltose, and saccharose but not esculin, mannitol, or inulin. Fifty-three percent of the group B streptococci from pigs and none of those from nutrias were lactose positive. Serotyping revealed that most of the group B streptococci from pigs were of serotype III and most of those from nutrias were of type Ia/c. Protein c was present as c beta antigen. All group B streptococci were susceptible to penicillin and bacitracin (10 U), and most of the porcine cultures were resistant to tetracycline. According to these results, group B streptococci from pigs and nutrias differ from bovine and human group B streptococci and seem to play no role in cross-infections between animals or between animals and humans.

Animals↗
PubMed1992

Serotyping and further characterization of group B streptococcal isolates from Indonesia.

Serotyping of 103 streptococci of serological group B isolated from human clinical specimens in Indonesia revealed mainly type pattern Ia/c and type patterns III and V, either alone or in combination with protein antigens c or R. Few cultures had serotype II and IV, none of the cultures had type antigen Ib or X. Extracts of one group B streptococcal culture reacted with antibodies specific to type antigens II, IV and R and one culture with antibodies specific to candidate type 7271. Protein antigen c was present as c alpha, c alpha, beta but not as c beta component. Group B streptococci with type antigen R grew generally as a granular sediment with clear supernatant, formed compact colonies in soft agar and reacted positively in the salt aggregation test. Group B streptococci without surface antigen R grew mainly with a uniform turbidity of the growth media, formed diffuse colonies in soft agar and were negative in the salt aggregation test.

Antigens, Bacterial↗
PubMed1992

Relationship between group B streptococcal serotypes and cell surface hydrophobicity.

Cell surface hydrophobicities of streptococci of serological group B were determined by the adherence of the bacteria to hexadecane droplets. A significant adherence to hexadecane was observed with the group B streptococcal type reference strains Ib, V, Ic, R and X, but not with those of serotype Ia, II, III and IV. Cultivation of the bacteria in microcapsule-inducing media reduced the hexadecane adherence properties. The adherence to hexadecane was not related to fibrinogen binding properties of the cultures. Screening a large number of group B streptococci isolated from humans and bovines revealed that those with polysaccharide type antigen alone were generally hydrophilic, those with protein antigen alone or with protein antigen in combination with polysaccharide antigen were mostly hydrophobic. Cultivation of the bacteria under microaerobic conditions or after a single mouse passage enhanced microcapsule production and correspondingly reduced the hexadecane adherence values. Treatment of the bacteria by guanidinium chloride or by neuraminidase enhanced the hexadecane adherence. The hydrophobic component on group B streptococcal surface appeared to be partly inactivated by heat or proteolytic treatment of the bacteria.

Alkanes↗
PubMed1991

Immuno-electronmicroscopic demonstration of alpha and beta components of group B streptococcal protein antigen c.

Affinity purified and absorbed monospecific antibodies against the protein type antigen c components c alpha and c beta were used in immuno-electronmicroscopic studies. As demonstrated with protein A gold particles the c alpha specific antibodies reacted with the c alpha antigen, the c beta specific antibodies with the c beta antigen. The respective antigens were distributed over the whole surface of the bacterial cells, mainly at the outermost layer of the cell wall.

Antigens, Bacterial↗
PubMed1991

Isolation and characterization of group B streptococcal type antigens X and R.

The group B streptococcal surface antigens X and R were isolated from culture supernatant by ammonium sulphate precipitation and subsequent high performance gel filtration (HPLC). The type antigens appeared in numerous protein bands. Type antigen X was in the range of 180 kD, type antigen R, in the range of 116 kD. The protein antigens reacted specifically with their homologous antisera in Western blot analysis and in immunoelectrophoresis, indicating that there was no immunological relationship between both proteins. Preparative isoelectric focusing of the X and R antigens revealed for both proteins isoelectric points at acid pH. Specific antibodies produced against the purified proteins could be used for routine serotyping without further absorption.

Agglutination Tests↗
PubMed1991

Influence of capsular neuraminic acid on properties of streptococci of serological group B.

Neuraminic acid is thought to be a critical virulence factor of group B streptococci. The present study was designed to further characterize a previously described type III group B streptococcus and its transposon-mutagenized asialo capsular mutant. The wild-type group B streptococcus grew as short chains with a uniform turbidity and had diffuse colonies in soft agar media. In contrast, the asialo mutant grew in fluid media as a granular sediment, formed significantly longer chains and had compact colonies in soft agar. These differences, possibly related to the surface charge of the bacteria, could also be demonstrated in salt aggregation tests and hexadecane adherence studies. The wild-type group B streptococcus showed hydrophilic, and the asialo mutant hydrophobic surface properties. Removal of neuraminic acid from the wild-type strain changed the surface properties from hydrophilic to hydrophobic. A similar masking effect of capsular neuraminic acid could be observed in adherence and phagocytosis experiments. In contrast to the wild-type strain, the asialo mutant adhered significantly more to buccal epithelial cells and was phagocytosed more by polymorphonuclear leucocytes. These altered properties might possibly be of importance for group B streptococcal pathogenicity.

Bacterial Adhesion↗
PubMed1991

Antibiotic resistance patterns and pigment production of streptococci of serological group B isolated from bovines and humans.

All 127 streptococci of serological group B isolated from bovines and humans were resistant to bacitracin (0.04 U) and gentamicin and susceptible to penicillin. Of the bovine isolates examined 10%, 8%, 22%, 2% and 30% were resistant to bacitracin (10 U), cefoxitin, clindamycin, erythromycin and tetracycline respectively. Of the human isolates 52%, 21%, 38%, 3% and 65% were resistant to bacitracin (10 U), cefoxitin, clindamycin, erythromycin and tetracycline respectively. Most of the bovine strains were susceptible, most of the human strains were resistant to bacitracin and tetracycline. A relation of tetracycline resistance to group B streptococcal microcapsule was proposed. Pigmentation studies revealed generally a weak pigmentation of bovine and a strong pigmentation of human group B streptococci. Antibiotic resistance patterns together with the ability to form a yellow to orange-red pigment might be used for characterization of individual cultures of group B streptococci.

Animals↗
PubMed1990

Distribution of B streptococcal type antigens among streptococci of serological groups B, G and L.

Serotyping of streptococci of serological group B isolated from humans revealed mainly the type patterns Ia/c and III/R. The protein antigen c components were c alpha beta, c alpha and less frequently, c beta. Extracts of two group B streptococcal cultures reacted with specific antiserum against type candidate 7271. Bovine group B streptococci mainly expressed the type antigens IV/X and NT/X. Protein antigen c occurred as c alpha beta, c alpha and less frequently as c beta component. Among the non group B streptococcal cultures used in this study, only those of serological groups G and L reacted with specific antisera against protein antigens R and X.

Agglutination Tests↗
PubMed1990

Demonstration of alpha and beta components of group B streptococcal protein antigen c in serum-soft agar.

Among 85 group B streptococcal cultures with protein type antigen c 56 cultures demonstrated a diffuse type of colony morphology in plain soft agar. The addition of monospecific antibodies against the protein antigen c components c alpha and c beta converted specifically the colony morphology from diffuse to compact. According to this results the serum-soft agar technique could also be used to further characterize individual cultures of group B streptococci with protein antigen c.

Animals↗