The activity of commercial antimicrobials, and essential oils and ethanolic extracts of Olea europaea on Streptococcus agalactiae isolated from pregnant women.

BACKGROUND: Streptococcus agalactiae also known as Group B Streptococcus (GBS) is a major cause of disease in pregnant women and new born babies where it causes early and late onset disease characterised by sepsis, pneumonia and meningitis. Ten to 37 % of pregnant women in the world are colonised with GBS while intrapartum antibiotic prophylaxis has led to significant reduction in early onset disease. The increase in drug resistant microorganisms has become a major threat. Development of vaccines is still in progress so there is need for new and safer alternatives to treatment. METHODS: Benzyl penicillin, Ampicillin, Cefotaxime, Ceftriaxone, Levofloxacin, Erythromycin, Clindamycin, Linezolid, Vancomycin, Tetracycline and Cotrimoxazole, Olea europaea leaf extracts and essential oil were tested against GBS isolates from South Africa and Namibia. RESULTS: The isolates showed 100% sensitivity to benzyl penicillin, ampicillin, ceftriaxone, levofloxacin, linezolid, vancomycin, O. europaea leaf extracts and essential oils. Only one isolate (0.6%) was resistant to cefotaxime and 23.4 and 10.4% were resistant to clindamycin and erythromycin respectively. CONCLUSION: GBS isolates showed sensitivity to O. europaea extracts at low minimum inhibitory concentrations. Β lactams are still the drugs of choice for treatment of GBS disease but O. europaea extracts potent as an alternative source of antimicrobials.

Prevalence and capsular type distribution of Streptococcus agalactiae isolated from pregnant women in Namibia and South Africa.

BACKGROUND: Streptococcus agalactiae or Group B Streptococcus (GBS) is the leading cause of neonatal morbidity and mortality resulting in septicaemia, bacteraemia and meningitis. Long term problems in children range from loss of hearing to mental retardation. While Intrapartum Antibiotic Prophylaxis (IAP) has reduced the incidence of S. agalactiae infection, it still remains the leading cause of disease in neonates. GBS has ten capsular types whose distribution varies across the world. Therefore, this study sought to determine the prevalence of GBS in Namibia and South Africa amongst pregnant women between 35 and 37 weeks gestation and elucidate the capsular types. METHODS: Lower vaginal and rectal swabs were collected from pregnant women between 35 and 37 weeks gestation. Five hundred and thirty pregnant women were recruited into the study in Windhoek, Namibia while one hundred pregnant women were recruited in the Eastern Cape, South Africa. The swabs were cultured on 5% sheep blood agar (Biomerieux, New Jersey, USA) for isolation of GBS. Presumptive isolates were confirmed using both the Vitek (2) and molecular techniques targeting the scpB gene. Capsular typing was performed in a multiplex PCR with capsular specific primer pairs. RESULTS: The prevalence of GBS in Namibia was 13.6 and 37% in South Africa respectively. In both countries most women were dually colonised with GBS. Capsular types II, III and V were the most prevalent. CONCLUSIONS: The prevalence of GBS in Namibia was lower than in South Africa in this study. The prevalence in both countries was not different from those reported in other African countries and around the world. The predominant capsular types in this study are the ones commonly associated with adverse maternal outcomes.

Antibiotic resistance of Streptococcus agalactiae isolated from pregnant women in Garankuwa, South Africa.

BACKGROUND: This study was undertaken to determine the susceptibility profile and the mechanism of antibiotic resistance in Group B streptococcus (GBS) isolates detected in vaginal and rectal swabs from pregnant women attending Dr George Mukhari Academic Hospital, a University Teaching Hospital in Pretoria, South Africa. METHODS: The samples were collected over an 11-month period, cultured on selective media (colistin and nalidixic acid agar and Todd-Hewitt broth), and GBS positively identified by using different morphological and biochemical tests. The susceptibility testing was done using the Kirby-Bauer and E test methods according to CLSI guidelines 2012. The D test method was used for the detection of inducible clindamycin resistance. Multiplex PCR with specific primers was used to detect different genes coding for resistance. RESULTS: Out of 413 samples collected, 128 (30.9%) were positive with GBS. The susceptibility testing revealed that 100% of isolates were sensitive to penicillin, ampicillin, vancomycin and high level gentamicin. Erythromycin and clindamycin resistance was 21.1 and 17.2%, respectively, in which 69% had harboured constitutive macrolide, lincosamide and streptogramin B (MLS(B)), 17.4% had inducible MLS(B). The M and L phenotypes were present in 6.8% each. The methylation of target encoded by ermB genes was the commonest mechanism of resistance observed in 55% of isolates, 38% of isolates had both ermB and linB genes and efflux pump mediated by mefA genes was also distributed among the isolates. CONCLUSIONS: The study reaffirmed the appropriateness of penicillin as the antibiotic of choice for treating GBS infection. However it identified the challenges of resistance to macrolides and lincosamides used as alternative drugs for individuals allergic to penicillin. More GBS treatment options for penicillin allergic patients need to be researched on.

Genetic analysis of the near full-length genome of an HIV type 1 A1/C unique recombinant form from northern South Africa.

Human immunodeficiency virus type 1 (HIV-1) has a high propensity for recombination. The epidemic in South Africa is predominantly driven by HIV-1 subtype C with occasional description of non-subtype C and intersubtype recombinant viruses. This report presents the genetic analysis of a unique recombinant variant from northern South Africa comprised exclusively of subsubtype A1 and subtype C parental viruses. Boot scanning analysis of the near full-length genome with the jumping profile Hidden Markov Model revealed a genomic arrangement with seven breakpoints of recombination alternating between subsubtype A1 and subtype C. Apparently, this is the first report of a unique HIV-1 A1/C recombinant form from northern South Africa and probably the fifth from South Africa. The epidemiologic implication of this variant is unknown.

Group B Streptococcus colonization during pregnancy and maternal-fetal transmission in Zimbabwe.

OBJECTIVE: To explore risk factors for group B Streptococcus (GBS) colonization during pregnancy and at delivery, estimate the predictive value of early GBS colonization for colonization at delivery and in the newborn, and explore the relationship to adverse perinatal factors. DESIGN AND SETTING: Cohort study of pregnant women from three communities in Zimbabwe. METHODS: Information collected by questionnaire at inclusion and from delivery records. Vaginal and rectal swabs collected for GBS culture at 20 and 26 weeks gestation, at delivery and from the newborn infant. MAIN OUTCOME MEASURES: GBS colonization in pregnancy, colonization of mother and newborn, and perinatal factors. RESULTS: GBS culture results were obtained at one or more occasion for 780 (75.2%) of 1,037 women recruited. Altogether, 470/780 women (60.3%) tested positive for GBS, with colonization rates at 20, 26 weeks and delivery of 47%, 24.2% and 21%, respectively. Positive GBS culture at 20 and 26 weeks gestation had a low positive predictive value on colonization at delivery and in the newborn. Women living in rural areas were significantly more often colonized than those who lived in urban areas (p < 0.001). Other socio-economic, demographic and obstetric factors were not statistically associated with GBS colonization. GBS transmission was not statistically significantly associated with adverse perinatal outcomes. CONCLUSIONS: GBS colonization was common among pregnant women in Zimbabwe. Dwelling in a rural area was significantly associated with GBS colonization while other risk factors were not. Early GBS colonization had a low predictive value for colonization at delivery and colonization was not associated with adverse perinatal outcome.

Putative novel surface-exposed Streptococcus agalactiae protein frequently expressed by the group B streptococcus from Zimbabwe.

Group B streptococci (GBS) express a variety of surface-exposed and strain-variable proteins which function as phenotypic markers and as antigens which are able to induce protective immunity in experimental settings. Among these proteins, the chimeric and immunologically cross-reacting alpha-like proteins are particularly important. Another protein, R3, which has been less well studied, occurred at a frequency of 21.5% in GBS from Zimbabwe and, notably, occurred in serotype V strains at a frequency of 75.9%. Working with rabbit antiserum raised against the R3 reference strain ATCC 49447 (strain 10/84; serotype V/R3) to detect the expression of the R3 protein, we recorded findings which suggested that strain 10/84 expressed a strain-variable protein antigen, in addition to R3. The antigen was detected by various enzyme-linked immunosorbent assay-based tests by using acid extract antigens or GBS whole-cell coats and by whole-cell-based Western blotting. We named the putative novel antigen the Z antigen. The Z antigen was a high-molecular-mass antigen that was susceptible to degradation by pepsin and trypsin but that was resistant to m-periodate oxidation and failed to show immunological cross-reactivity with any of a variety of other GBS protein antigens. The Z antigen was expressed by 33/121 (27.2%) of strains of a Zimbabwean GBS strain collection and by 64.2% and 72.4% of the type Ib and type V strains, respectively, and was occasionally expressed by GBS of other capsular serotypes. Thus, the putative novel GBS protein named Z showed distinct capsular antigen associations and presented as an important phenotypic marker in GBS from Zimbabwe. It may be an important antigen in GBS from larger areas of southern Africa. Its prevalence in GBS from Western countries is not known.

Distinctive features of surface-anchored proteins of Streptococcus agalactiae strains from Zimbabwe revealed by PCR and dot blotting.

The distribution of capsular polysaccharide (CPS) types and subtypes (serovariants) among 121 group B streptococcus (GBS) strains from Zimbabwe was examined. PCR was used for the detection of both CPS types and the surface-anchored and strain-variable proteins Calpha, Cbeta, Alp1, Alp2, Alp3, R4/Rib, and Alp4. The R3 protein was detected by an antibody-based method using monoclonal anti-R3 antibody in dot blotting. The CPS types detected, Ia (15.7% of strains), Ib (11.6%), II (8.3%), III (38.8%), V (24.0%), and nontypeable (1.7%), were essentially as expected on the basis of data from Western countries. The type V strains showed distinctive features with respect to protein markers in that Alp3 was detected in only 6.9% of the isolates while R3 occurred in 75.9% and R4/Rib occurred in 37.9% of the isolates. R3 occurred nearly always in combination with one of the alpha-like (Alp) proteins, and it was the third most common of the proteins studied. These results show that type V GBS strains from Zimbabwe differed from type V strains from other geographical areas and also emphasize the importance of the R3 protein in GBS serotyping and its potential importance in the immunobiology of GBS, including a potential role in a future GBS vaccine.

Recognition of different epitopes on the Ca & R4 proteins of group B streptococci by normal human & antibodies induced in animals.

BACKGROUND & OBJECTIVES: Levels of protective antibodies against Calpha and R4 proteins of the group B streptococci (GBS) have been measured in humans. The findings indicated that the human anti Calpha and anti-R4 antibodies may recognize targets which are different from those recognized by antibodies raised in animals. In the present study normal human serum antibodies which target the GBS proteins Calpha and R4 and immune anti-Calpha and anti -R4 antibodies raised in animals were compared. METHODS: The antigens were prepared by extraction of whole cells of GBS with trypsin and purified, and the testing was done by ELISA and Western blotting. RESULTS: The immune antibodies showed specificity for the corresponding protein and targeted proteins which had been denatured by hot sodium dodecyl sulphate (SDS) or by heating in a nearly neutral buffer. The human antibodies targeted a site(s) common to Calpha and R4 and failed to bind to the denatured proteins. The bulk of antibodies in sera from healthy pregnant women was directed against the SDS and heat labile determinant(s). INTERPRETATION & CONCLUSION: The present results indicated that the immune antibodies were directed against sequential epitopes and the normal human serum antibodies against epitopes determined by molecular conformation.

Antibodies raised in animals against the Streptococcus agalactiae proteins c alpha and R4 and normal human serum antibodies target distinct epitopes.

The targets for normal human serum antibodies that react with proteins c(alpha) and R4 isolated from group B streptococci (GBS; Streptococcus agalactiae) have been studied and compared with the targets for murine monoclonal and rabbit polyclonal antibodies raised against these proteins. The proteins were extracted by trypsin digestion and purified by precipitations and gel filtration and testing was based on enzyme immunoassays. The immune antibodies showed specificity for the corresponding protein, targeted that protein in Western blotting and recognized their targets after heat treatment (100 degrees C) of the proteins. Human antibodies in a commercial gammaglobulin preparation targeted a site(s) common to c(alpha) and R4. This target failed to bind the antibodies in Western blotting and was destroyed by heating. c(alpha)- and R4-reactive antibodies in sera from healthy pregnant women recognized the common, heat-labile determinant(s), but contained little or no antibodies against the heat-stable c(alpha)- or R4-specific determinants. These results are consistent with the notions that (i) the normal human antibodies and the immunization-induced animal antibodies targeted different sites on the c(alpha) and R4 proteins and that (ii) the natural human antibodies targeted conformational epitopes and the immune antibodies targeted linear epitopes. These findings are important for further clarification of GBS immunology and immunoprotection in humans.

Typing of human isolates of Streptococcus agalactiae (group B streptococcus, GBS) strains from Zimbabwe.

Serotyping and genotyping are important tools in epidemiological studies of group B streptococcal (GBS) infections, which are important diseases in man, particularly in newborns. In the present study, 241 GBS isolates from Zimbabwe, comprising 124 carrier isolates from pregnant women and 117 isolates from patients hospitalised for various diseases, were serotyped. Antibodies specific for the capsular polysaccharide antigens (CPAs) Ia, Ib and II-V and antibodies specific for the surface-localised proteins, c(alpha), c(beta), R1, R3 and R4 were used for serotyping. Strains of the CPA types Ia (17%), III (47.7%) and V (23.2%) predominated. Of the various protein antigens, c(alpha) and R4 were expressed with highest frequency, c(alpha) by 100% of the CPA type Ia strains and R4 by 92% of the CPA type III strains. The R3 protein occurred frequently (24%), especially in type V strains (84%). A total of 25 serovariants was detected in the strain collection with the variants Ia/c(alpha) (16%), III/R4 (43.5%) and V/c(alpha), R3 (14.1%) occurring with the highest frequency. Serotype and subtype distribution of the carrier isolates were essentially similar to those of the disease-associated isolates. Genomic heterogeneity was demonstrated by pulsed-field gel electrophoresis of type III/R4 and type V/c(alpha), R3 isolates, but to a much lesser extent than recorded with Norwegian strains. These results demonstrate that many variants of GBS occur in the Zimbabwean population. The data obtained may assist in the formulation of a possible future GBS vaccine for Zimbabwe and perhaps for other African countries.