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PubMed2000

[Evaluation of cariogenic potential of Streptococcus mutans isolated from caries-free and -active persons: abilities to synthesize water-soluble and -insoluble glucans].

OBJECTIVE: In this study, authors investigated abilities of Streptococcus mutans (serotype c) strains to synthesize water-soluble and water-insoluble glucans. METHODS: Streptococcus mutans strains were isolated from people with different carious experiences, which were divided into two groups: caries-free (DMFS = 0) group including 19 persons and caries-active group(DMFS > or = 6) including 40 persons. Totally 105 genotypes of Streptococcus mutans strains were obtained, including 22 strains from the caries-free group and 83 strains from the caries-active group. The differences of abilities to synthesize water-soluble and water-insoluble glucans between these two groups were compared in order to find the correlationship between the synthesis of glucans and caries experience. Then, Streptococcus mutans were cultured in TPY liquid medium containing 1% sucrose in an anaerobic incubator at 37 degrees C for 24 hours. Glucans synthesized by Streptococcus mutans was qualified by using infrared spectrophotometry. The amounts of water-soluble and water-insoluble glucans were measured by using the anthron method. RESULTS: According to the same absorption tops position analysed by infrared spectrophotometry, glucans samples were certified. The amounts of glucans synthesized by Streptococcus mutans strains were different between strains of different genotypes even isolated from the same person. Mostly, the amount of water-insoluble glucans was higher than that of water-soluble glucans between different genotype Streptococcus mutans strains. The oral environments of patients in the caries-active group harbored more Streptococcus mutans strains with higher water-soluble glucans producing ability than those of the caries-free group did (P < 0.05), and patients of the caries-active group also harbored more Streptococcus mutans strains with higher water-insoluble glucans producing ability than those of the caries-free group did(P < 0.01). CONCLUSION: 1. Glucosyltranferases of different genotype strains are different in glucans production, and different genotype strains relate to different cariogenic abilities. 2. Glucans was one of cariogenic factors, and water-insoluble glucans was more important than water-soluble glucans in cariogenic ability of Streptococcus mutans. 3. The differences in glucans production of isolated strains might relate to differences in carious experiences.

Dental Caries↗
PubMed1998

Emergence of Streptococcus pyogenes strains resistant to erythromycin in Gipuzkoa, Spain.

The aim of this study was to determine the evolution of resistance to macrolides and other antibiotics in strains of Streptococcus pyogenes isolated in the province of Gipuzkoa, Spain. During the period 1984-1996, all 2561 strains of Streptococcus pyogenes studied showed full susceptibility to penicillin. Until 1990, only 1.2% of Streptococcus pyogenes isolates were resistant to erythromycin. Since then, resistance to erythromycin increased every year until 1995, when 34.8% (87/250) of Streptococcus pyogenes strains were found to be resistant. In 1996 the rate of resistance to erythromycin was 17.8% (75/422). During the study period, 96.1% (246/256) of the Streptococcus pyogenes isolates resistant to erythromycin were susceptible to clindamycin. Of the remaining erythromycin-resistant Streptococcus pyogenes strains, resistance to clindamycin was constitutive in seven strains and inducible in three. When investigated by the polymerase chain reaction (PCR), all Streptococcus pyogenes strains resistant to erythromycin and susceptible to clindamycin showed the 1.4 kb fragment of the mefA gene, recently described as the novel macrolide-efflux-resistance determinant. The most frequent T-agglutination patterns among Streptococcus pyogenes resistant to erythromycin were T4 and T8,25. The emergence and rapid spread of erythromycin-resistant Streptococcus pyogenes in Gipuzkoa and its relationship to the presence of the mefA gene are described.

Agglutination↗
PubMed1985

Fatty acid composition of Streptococcus milleri.

The cellular fatty acids of 31 strains belonging to the Streptococcus milleri group were analysed by capillary gas-liquid chromatography. Results were compared with findings from biochemical differentiation of the strains into Streptococcus constellatus (two strains), Streptococcus anginosus (16 strains) and Streptococcus intermedius (13 strains). Eight strains of various other streptococci were included as internal references, including three strains of streptococcus morbillorum, three strains of beta-hemolytic streptococci, and two strains of enterococci. The Streptococcus milleri strains formed a very homogeneous group according to fatty acid composition and were easily differentiated from other groups. However, within the group, it was not possible to differentiate Streptococcus constellatus, Streptococcus anginosus and Streptococcus intermedius by fatty acid composition alone.

Chromatography, Gas↗
PubMed2006

Tigecycline (GAR-936) activity against Streptococcus gallolyticus (bovis) and viridans group streptococci.

Viridans group streptococci including Streptococcus gallolyticus (formerly S. bovis) represent serious invasive pathogens often associated with endocarditis or sepsis among immunocompromised or cancer patients. Tigecycline (GAR-936), the first clinically studied glycylcycline, has a potent gram-positive activity with a potential treatment option for these streptococcal infections. The studied collection (848 strains) included 100 isolates each of Streptococcus anginosus, Streptococcus constellatus, Streptococcus intermedius, Streptococcus mitis, Streptococcus oralis, Streptococcus salivarius, Streptococcus sanguis, and fewer strains of S. gallolyticus (98 strains) and Streptococcus mutans (50 strains). These strains were isolated from patients on 3 continents in the SENTRY Antimicrobial Surveillance Program and tested for susceptibility and interpreted by Clinical and Laboratory Standards Institute broth microdilution methods and criteria (< or = 0.25 microg/mL for tigecycline per US Food and Drug Administration). Penicillin susceptibility rates for the entire collection varied from 61% (S. sanguis) to 98% (S. constellatus), and macrolide susceptibility was also compromised (49-88%; average, 69%). Tigecycline was active against all isolates tested, in contrast to tetracycline resistance rates of 8-66%, and highest for S. gallolyticus. In conclusion tigecycline was quite active against bacteremic isolates of viridans group streptococci species and S. gallolyticus with an overall MIC90 at < or = 0.06 microg/mL; the highest MIC was only 0.25 microg/mL.

Anti-Bacterial Agents↗
PubMedDate not supplied

Restoration-related salivary Streptococcus mutans level: a dental caries risk factor?

OBJECTIVES: The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans. METHODS: The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled, without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression. RESULTS: Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66: prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean. 0.75: prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth. CONCLUSIONS: In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth.

Child↗
PubMed1995

Investigation of oral alpha-streptococcus showing inhibitory activity against pathogens in children with tonsillitis.

The incidence of oral alpha-streptococcus with inhibitory activity against group A streptococcus, as a defense mechanism against bacterial infection in the oral cavity, was investigated in pediatric individuals with tonsillitis. Infection by group A streptococcus appeared to be common in children, because the detection rate of inhibitory alpha-streptococcus in healthy children as well as pediatric patients with tonsillitis was lower than in adults and elderly patients. In particular, the detection rate of these strains was predominantly low in patients with beta-streptococcus. Among pediatric patients scheduled for tonsillectomy, the detection rate of inhibitory alpha-streptococcus was low preoperatively. However, the rate was markedly increased after surgery. The high postoperative detection rate of these strains reflected the decreased incidence of group A streptococcal infection. The results of this investigation of bacterial interference between oral alpha-streptococcus and group A streptococcus suggested that surgical treatment is a more effective approach for improving the oral bacterial flora in children with recurrent tonsillitis.

Adult↗
PubMed2002

Bacteremia due to beta-hemolytic Streptococcus group G: increasing incidence and clinical characteristics of patients.

PURPOSE: To describe the epidemiology and clinical characteristics of patients diagnosed with Streptococcus group G bacteremia from 1990 to 1999 at a community teaching hospital in Israel. SUBJECTS AND METHODS: We calculated the annual rate of bacteremia with Streptococcus group G, expressed as a percentage of positive blood cultures (after excluding contaminants) and per 1000 admissions. Medical records of patients with Streptococcus group G were reviewed. RESULTS: During the 10-year study period, there was a total of 7415 positive blood cultures, 327 (4.4%) of which were beta-hemolytic Streptococcus species, of which 49 (15%) were group G. The rate of Streptococcus group G bacteremia per 1000 admissions increased from zero (0/18,783) in 1990 to 0.41 (13/31,440) in 1999 (P = 0.001), surpassing Streptococcus group A in frequency. Of the 47 patients with Streptococcus group G, 40 medical records were available for review: 25 patients (63%) were older than 75 years and 32 (80%) were men. The probable source of Streptococcus group G bacteremia was a skin or soft tissue infection in 37 patients (93%). Six of the 40 patients died. CONCLUSION: Community-acquired group G streptococcal bacteremia occurred with increasing frequency from 1990 to 1999 at our hospital. Most patients were elderly men, and the portal of entry was usually the skin or soft tissue. Our findings suggest a change in the epidemiology of bacteremia due to beta-hemolytic streptococci.

Adolescent↗
PubMed1995

Evaluation of the automicrobic system for the identification of Streptococcus mutans.

The performance of the Automicrobic System with the Vitek gram-positive identification card (bioMérieux, France) in identifying strains of Streptococcus mutans was studied. Of 160 strains assayed, 72.5% were confirmed to be Streptococcus mutans; the remainder were identified as other species of streptocci (Streptococcus bovis, Streptococcus uberis, Streptococcus anginosus, Streptococcus sanguis I and II, Streptococcus intermedius, and Streptococcus constellatus).

Bacterial Typing Techniques↗
PubMed1995

The accuracy and patient preference for self-collected group B Streptococcus cultures.

OBJECTIVE: Our purpose was to determine the accuracy of and patient attitudes regarding self-collected group B Streptococcus cultures. STUDY DESIGN: Women seen for prenatal care at 24 to 42 weeks' gestation were asked to collect distal vaginal and anal samples for group B Streptococcus. Subsequently, distal vaginal and anal samples were obtained by the nurse. The patients were then asked their preference toward self-sampling. RESULTS: A total of 251 women participated in the study. The incidence of positive group B Streptococcus cultures was 12.7%, 9.6%, 10.0%, and 7.6% for the patient-collected vaginal and anal and nurse-collected vaginal and anal specimens, respectively. The incidence of group B Streptococcus carriage was 17.5% and 13.5% for any positive patient- or provider-collected specimens, respectively, and 19.1% for any positive culture. Single patient-collected vaginal and anal and nurse-collected vaginal and anal samples were insensitive for group B Streptococcus carriage (67%, 50%, 52%, 40%, respectively). The combination of patient-collected samples was more sensitive than nurse-collected samples (sensitivity 91.7% vs 70.8%, p < 0.05). Repeat sampling of the vagina or anal canal did not offer significant additional benefit to a single culture. Overall, patient-collected samples were 98.4% accurate in predicting group B Streptococcus carriage versus 94.4% for nurses. A total of 58% of women preferred obtaining their own specimens, whereas 9.6% found the technique difficult. Ninety percent desired the option of self-sampling in the future. CONCLUSIONS: Single vaginal or anal cultures were insensitive in detecting group B Streptococcus carriage. Combined patient-collected cultures were more sensitive than provider-collected specimens. On the basis of accuracy and patient preference, women should be given the opportunity of combined vaginal-anal self-sampling for group B Streptococcus when indicated.

Adolescent↗
PubMed1996

Group B Streptococcus and preterm premature rupture of membranes: a randomized, double-blind clinical trial of antepartum ampicillin.

OBJECTIVE: Our purpose was to determine whether ampicillin prolongs the latency period after preterm premature rupture of membranes in patients colonized with group B Streptococcus. STUDY DESIGN: Sixty patients presenting at < or = 35 weeks' gestation with preterm premature rupture of membranes were included in the study. Cervical, vaginal, and perianal cultures for group B premature rupture were obtained. The participants then were randomized to receive either ampicillin or placebo intravenously for 24 hours and then orally until hospital discharge or delivery. All patients were treated without the use of tocolytic drugs. The chi(2) test, Fisher exact test, Student t test, and Wilcoxon signed-rank test were used for statistical analysis when appropriate. RESULTS: Fifteen patients had cultures positive for group B Streptococcus. Patients with cultures positive for group B Streptococcus who received ampicillin (n = 8) were more likely not to have been delivered of their infants 48 hours after preterm premature rupture of membranes than patients who received placebo (n = 7), a statistically significant difference (100% vs 43%; p = 0.01; relative risk 2.3; 95% confidence interval 1.2 to 4.5). Seven days after preterm premature rupture of membranes, however, there was no significant difference in percentage of patients with cultures positive for group B Streptococcus who remained undelivered (63% vs 29%; p = 0.19; relative risk, 2.2; 95% confidence interval 0.7 to 7.1). Among patients with cultures negative for group B Streptococcus, there was a trend for patients who received ampicillin to remain undelivered 48 hours after preterm premature rupture of membranes compared with those who received placebo, but the difference was not statistically significant (87% vs 64%; p = 0.07; relative risk, 1.4; 95% confidence interval 1.0 to 1.9). There also was no difference in percentage of patients with cultures negative for group B Streptococcus who remained undelivered 7 days after preterm premature rupture of membranes 39% vs 27%; p = 0.40; relative risk, 1.4; 95% confidence interval 0.61 to 3.3). There were no differences between the treatment and placebo arms of the group B Streptococcus positive and negative cohorts in incidence of cesarean section, chorioamnionitis, postpartum endometritis, or neonatal infectious morbidity. CONCLUSION: Use of antibiotics increases the percentage of patients with cultures positive for group B Streptococcus who remain undelivered 48 hours after preterm premature rupture of membranes. Antibiotic therapy may provide a window of opportunity for maternal treatment with corticosteroids to decrease the risk for neonatal morbidity among these preterm gestations.

Adult↗
PubMed2003

Correlates of antibiotic-resistant group B streptococcus isolated from pregnant women.

Despite antibiotic prophylaxis for at-risk mothers during labor and delivery, group B streptococcus still causes substantial morbidity and mortality among newborns. Resistance to antibiotics recommended for penicillin-allergic pregnant women, such as erythromycin and clindamycin, has increased. A better understanding of factors associated with group B streptococcus resistance is essential to effectively prevent group B streptococcus disease.A total of 117 sequential group B streptococcus isolates were obtained between August 1999 and March 2000 from pregnant women at the University of Michigan Medical Center. Serotype and susceptibility to ten antimicrobials using disk diffusion with E-test for confirmation were determined, and the association between several host factors and colonization with a resistant strain was evaluated. Group B streptococcus was frequently resistant to erythromycin (29%) and clindamycin (21%) but was susceptible to all other antimicrobials tested. A stepwise logistic regression model revealed that black ethnicity (P =.02) and carriage of a serotype V strain (P =.01) were associated with group B streptococcus resistance. Among this population of pregnant women, black ethnicity and serotype V were the strongest predictors of colonization with an erythromycin- or clindamycin-resistant group B streptococcus strain. A better understanding of factors associated with antibiotic resistance is needed to minimize group B streptococcus disease risks and to maximize effective chemoprophylaxis.

Adolescent↗
PubMed2004

Antenatal screening and intrapartum management of Group B Streptococcus in the UK.

OBJECTIVE: To determine whether there has been any change in UK policy for the screening and intrapartum management of Group B Streptococcus in pregnancy over a two year period. DESIGN: Two national survey's of practice carried out in 1999 and 2001. SETTING: All obstetric units in the UK. POPULATION: Clinical directors of maternity services. METHODS: A questionnaire was sent to all clinical directors of maternity services in the UK requesting information about their policy and practice with respect to antenatal screening for Group B Streptococcus colonisation. Reminders were sent after one month. MAIN OUTCOME MEASURES: Number of maternity units in the UK screening and offering intrapartum antibiotic prophylaxis for Group B Streptococcus colonisation in pregnancy. RESULTS: The response rates were 84% in 1999 and 82% in 2001. Of the responding units, six (3%) in 1999 and four (2%) in 2001 used vaginal swab based screening for Group B Streptococcus colonisation in the antenatal period. In 1999, intrapartum antibiotic prophylaxis was offered to women with a previous baby affected by Group B Streptococcus in 85% (176/207) of maternity units and in 2001 this had risen to 95% (193/203). Similarly, in 1999 intrapartum antibiotic prophylaxis was offered to women who were known carriers of Group B Streptococcus in 87% (179/207) of maternity units and in 2001 this had risen to 95% (193/203). Appropriate dosage of a recommended antibiotic was prescribed in 7% (9/123) units in 1999 and in 20% (35/178) units in 2001. CONCLUSIONS: Although intrapartum antibiotic prophylaxis for women at high risk of giving birth to babies with Group B Streptococcus is widely practiced in the UK, a programme of antenatal screening for Group B Streptococcus colonisation has not been adopted along the lines advocated in the USA. There therefore remains an opportunity to evaluate such a screening programme in a randomised trial.

Antibiotic Prophylaxis↗
PubMed1989

DNA probe for identification of Streptococcus pneumoniae.

A total of 287 clinical isolates of Streptococcus pneumoniae (pneumococcus) were tested for their ability to undergo autolysis when treated with sodium deoxycholate. The test was positive for all but one isolate, strain DOC-1. This autolysis required the activity of an enzyme which is unique and characteristic of S. pneumoniae: a choline-dependent N-acetylmuramoyl-L-alanine amidase, the gene product of the lytA gene. We used lytA as a DNA probe to test the distribution of the autolysin gene among clinical isolates of S. pneumoniae. In dot blot hybridization experiments our probe reacted with the DNA of 60 of 60 strains tested, including the autolysis-deficient clinical isolate DOC-1. No hybridization occurred when strains of Streptococcus sanguis, Streptococcus mutans, Streptococcus pyogenes, Streptococcus (Enterococcus) faecalis, Streptococcus (Enterococcus) faecium, Streptococcus agalactiae, and Streptococcus bovis were tested. The lytA gene appears to be an ideal candidate for use as a DNA probe for the identification of S. pneumoniae.

Amidohydrolases↗
PubMed1991

Evaluation of two fluorogenic assays for identification of Streptococcus species isolated from bovine mammary glands.

Liquid and agar assays that utilized 4-methylumbelliferyl-conjugated beta-D-glucuronide, beta-D-galactoside, or N-acetyl-beta-D-glucosaminide, and agglutination by Dolichos biflorus lectin were evaluated for identification of Streptococcus species isolated from bovine mammary glands. A greater number of Streptococcus uberis isolates were negative for N-acetyl-beta-D-glucosaminidase by the liquid assay compared with the agar assay. Enzyme profiles for Streptococcus dysgalactiae were similar by both assays. Streptococcus dysgalactiae was the only species that agglutinated when mixed with lectin from D. biflorus. Most Streptococcus agalactiae isolates were positive for beta-D-glucuronidase and beta-D-galactosidase by both assays. Two Streptococcus equinus strains had negative enzyme profiles by the liquid assay; however, both strains had enzyme profiles consistent for S. equinus by the agar method. Incorporation of 4-methylumbelliferyl-conjugated substrates into trypticase soy agar did not appear to alter agar characteristics and eliminated aliquoting substrates and inoculating tubes. More than one enzyme profile was produced per Streptococcus species or serogroup by both methods. However, some profiles were similar between species, which hindered accurate identification of Streptococcus species.

Acetylglucosaminidase↗
PubMed1988

Partial characterisation of the inhibitory substances produced by Streptococcus oralis and related species.

The production of inhibitory substances was sought by deferred antagonism. Streptococcus oralis, Streptococcus mitis and Streptococcus sanguis produced bactericidal concentrations of hydrogen peroxide, but no detectable bacteriocin. Actinomycetes and Neisseria pharyngis were particularly susceptible to the lethal action of hydrogen peroxide. Streptococcus milleri produced bactericidal concentrations of hydrogen peroxide and bacteriocin-like substances. S. oralis strains were inhibited by the bacteriocin-like products of strains of Streptococcus bovis, Streptococcus faecalis, Streptococcus mutans and Streptococcus salivarius. Inhibition was due neither to complete bacteriophage nor to fermentation end-products. Extracellular polysaccharides formed during growth could not protect sensitive strains from the effect of hydrogen peroxide or bacteriocin-like substances.

Actinomycetales↗
PubMed1988

Group B streptococcus and preterm rupture of membranes.

The effect of cervical group B streptococcus on the conservative management of preterm premature rupture of membranes was examined in 140 consecutive patients. Upon the patient's admission, we obtained cervical cultures for group B streptococcus, genital mycoplasmas, and chlamydia. Patients with and without group B streptococcus were compared. Group B streptococcus patients had earlier rupture of membranes (30.7 versus 31.6 weeks) and shorter latent periods (76.8 versus 138.5 hours). Intra-amniotic infection (six of 16 versus 26 of 120) and endometritis (four of ten versus three of 94) were significantly more common in group B streptococcus patients. Neonates of mothers positive for group B streptococcus were smaller (1749 +/- 844 versus 2100 +/- 779 g) and more likely to have infectious complications (eight of 16 versus 29 of 120; P less than .01). Control for the presence of mycoplasmas, chlamydia, listeria, or gonorrhea failed to change the significance of these results. The usual policy was to use intrapartum ampicillin prophylaxis in asymptomatic group B streptococcus patients. However, only four of 16 remained asymptomatic and had latent periods long enough for the results of cultures obtained on admission to be available. We conclude that group B streptococcus significantly complicates the conservative management of preterm premature rupture of membranes and that the effectiveness of intrapartum prophylactic ampicillin may be compromised by awaiting the results of conventional cultures to define colonized patients.

Adult↗
PubMed1996

Mode of action of a lysostaphin-like bacteriolytic agent produced by Streptococcus zooepidemicus 4881.

Electron microscopy of zoocin A-treated sensitive streptococcus cells revealed cytoplasmic disruption and ultimately complete rupture of the cell wall. Culture viability and optical density were shown to decrease rapidly and simultaneously in Streptococcus pyogenes FF22 but less quickly in the relatively more resistant Streptococcus mutans 10449. Zoocin A was shown to cleave hexaglycine in a colorimetric cell-free microtiter assay system, and it is concluded that the killing action of zoocin A, like that of lysostaphin, is most probably the result of direct cleavage of the peptidoglycan cross-links in the cell wall. The relationship between sensitivity to zoocin A and the peptidoglycan cross-linkage structure of Streptococcus zooepidemicus, Lactococcus spp., S. pyogenes, Streptococcus gordonii, Streptococcus oralis, S. mutans, and Streptococcus rattus has been evaluated.

Anti-Bacterial Agents↗
PubMed1998

Acid-regulated proteins induced by Streptococcus mutans and other oral bacteria during acid shock.

Our previous research has demonstrated that with the more aciduric oral bacteria, an acid shock to sub-lethal pH values results in the induction of an acid tolerance response that protects the cells at extremely low pH (pH 3.0-4.0) that kills unadapted control cells maintained at pH 7.5 (Oral Microbiol Immunol 1997: 12: 266-273). In this study, we were interested in comparing the protein profiles of acid-shocked and control cells of nine organisms from three acid-ogenic genera that could be categorized as strong, weak and non-acid responders in an attempt to identify proteins that could be classified as acid-regulated proteins and which may be important in the process of survival at very low pH. For this, log-phase cultures were rapidly acidified from pH 7.5 to 5.5 in the presence of [14C]-amino acids for varying periods up to 2 h, the period previously shown to be required for maximum induction of the acid response. The cells were extracted for total protein and subjected to one-dimensional sodium dodecyl sulfate-polyacrylamide chromatography with comparable control and acid-shocked protein profiles compared by scanning and computer analysis. Of particular interest were the proteins in the acid-shocked cells that showed enhanced labeling (i.e., synthesis) over the control cells, since these were considered acid-regulated proteins of importance in pH homeostasis. Streptococcus mutans LT11 generated the most rapid and complex pattern: a total of 36 acid-regulated proteins showing enhanced synthesis, with 25 appearing within the first 30 min of acid shock. The enhanced synthesis was transient with all proteins, with the exception of two with molecular weights of 50/49 and 33/32 kDa. Within the acid-regulated proteins were proteins having molecular weights comparable to the heat shock proteins and the various subunits of the membrane H+/ATPase. By comparison, the strong responder, Lactobacillus casei 151, showed the enhanced formation of only nine proteins within the first 30 min of the acid shock, with a total of 11 acid-regulated proteins formed during the 2-h adaptation period with enhanced synthesis transient for seven of these proteins. Streptococcus salivarius AT2 and Streptococcus gordonii TH12 had the formation of 6 and 8 proteins enhanced, while the weakly responding organisms, Streptococcus sanguis ATCC 10,556 and Streptococcus oralis ATCC 10,557, exhibited 8 and 6 such proteins, respectively. Even non-responding strains unable to survive at very low pH, such as Streptococcus sobrinus CH125/43, Streptococcus mitis ATCC 12,261 and Actinomyces naeslundii 301-13 showed the initial formation of 3-9 acid-regulated proteins, but protein synthesis was not sustained over the entire adaptation period. Clearly, the survival of oral bacteria at very low pH is related, not to the total number of the acid-regulated proteins induced per se but to the formation of key proteins that function to augment normal pH homeostasis.

Acids↗