Boy M. Bachtiar

AI-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation

Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.

Enterococcus faecalis with capsule polysaccharides type 2 and biofilm‐forming capacity in Indonesians requiring endodontic treatment

AIM The aim of the present study was to evaluate the genetic diversity of Enterococcus faecalis (E. faecalis) strains isolated from saliva and infected root canal samples from Indonesians requiring endodontic treatment. METHODS A total of 50 isolates were genotyped using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) and analyzed for locus polymorphisms of their capsule polysaccharides (CPS) and for biofilm-forming capabilities. RESULTS It was shown that all E. faecalis isolates shared >60% similarity. A higher degree of diversity of E. faecalis was observed in cluster 1 (C1, 28%) and cluster 2 (C2, 22%) from samples isolated from infected root canals. CPS type 2 was the dominant form observed in five clusters (C1-C5), but there was no relationship between the origins of these isolates. In contrast, all isolates in cluster C5 were of root canal origin, and 50% were associated with a strong biofilm phenotype. Five unclustered strains were saliva isolates (<60% similarity). Most of these strains showed weak biofilm capability. CONCLUSIONS E. faecalis CPS type 2 is relatively common in Indonesians requiring endodontic treatment, and there are differences in the biofilm-forming abilities produced by CPS type 2 strains in all isolates depending on the source. In addition, there is no relationship between the ERIC-PCR profile and biofilm formation.

PDMS Surface Modification Using Biomachining Method for Biomedical Application

Engineering a cell-friendly material in a form of lab-on-chip is the main goal of this study. The chip was made of polydimethyl siloxane (PDMS) with a surface modification to realize a groovy structure on its surface. This groovy surface was naturally and randomly designed via biomachining process. This measure was aimed to improve the cell attachment on the PDMS surface that always known as hydrophobic surface. The biomachined surface of mold and also products were characterized as surface roughness and wettability. The result shows that the biomachining process were able to be characterized in three classes of roughness on the surface of PDMS.

Inhibition of Candida albicans biofilm development by unencapsulated Enterococcus faecalis cps2

Background/purpose In the oral environment, Candida albicans interacts with many bacteria, including Enterococcus faecalis. We investigated the susceptibility of C. albicans biofilm development to the presence of unencapsulated E. faecalis cps2 in comparison with reference strains (E. faecalis ATCC 29212) or their respective spent medium (collected at 6 hours). Material and methods Crystal violet stain was used to measure the total biofilm mass, whereas quantitative real-time polymerase chain reaction was used to analyze the change in expression of the mRNA of hypha morphology (ALS1 and ALS3) and biofilm maturation (EFB1). Results At the intermediate stage, C. albicans resisted the presence of each E. faecalis strain tested and their spent medium. However, at the maturation stage, the unencapsulated strain was stronger in reducing C. albicans biofilms than the reference strain (P < 0.05). At this maturation stage, the transcription levels of each gene tested decreased in the presence of either E. faecalis strains or their respective spent medium. The unencapsulated strain was more pronounced in reducing ALS1/ALS3 expression, whereas the respective spent medium had a similar capability to restrict the expression of EFB1. Conclusion This study showed, the unencapsulated strain is more effective in inhibiting C. albicans biofilm development compared with the reference strains. In contrast, the secreted molecules produced by each strain tested are necessary in controlling the growths of C. albicans biofilm.

Delivery of Amphotericin B to Candida albicans by Using Biomachined Lab-on-a-Chip

This paper investigates the ability of biomachined lab-on-a-chip (LoC) to perform drug testing of Amphotericin B to the Candida albicans. The chip is made of polydimethyl siloxane (PDMS). Molds are patterned using CNC milling followed by biomachining. CNC milling process creates channel features on the bottom mold, while biomachining forms rough surface on the channels. After the molds are created, LoC can be manufactured using those molds. Hence, contour surface on LoC’s channels is also realized following the mold surface. Later, Candida albicans is seeded on the LoC’s channels for 24 and 48 hours with the continuous flow of Yeast Nitrogen Base (YNB) Sterile. Then, cell viability is tested using 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium (MTT).The result shows that C. albicans could adhere and grow in the LoC channels. Based on this result, drug testing is conducted in the presence and absence of Amphotericin B (Amp B) under two schemes: without (static) and with (dynamic) the continuous flow of YNB Sterile and Amp B. After 48 hour incubation period, C. albicans biofilm of 28.72 % is shown during dynamic scheme, whereas static scheme had C. albicans biofilm of 99.32 % indicating that the dynamic scheme provides a better efficacy compared to the static scheme.

The risk reduction of recurrent periodontal pathogens of local application minocycline HCl 2% gel, used as an adjunct to scaling and root planing for chronic periodontitis treatment

Background The aim of this study was to evaluate the clinical and microbiological effects of local application minocycline HCl 2% gel, used as an adjunct to scaling and root planing (SRP) for treatment of chronic periodontitis (CP). CP is an inflammation of periodontal tissue that is caused mainly by bacterial infection, where periodontal destruction such as loss of attachment and bone destruction occurred. Methods A total of 81 subjects with moderate to severe periodontitis whose baseline clinical attachment loss (CAL) was ≥4 mm were randomly assigned to receive SRP alone (control group, N=39) or SRP followed by four times of local application of minocycline HCl gel (Periocline) once a week (test group, N=42). Pocket depth, CAL, and papilla bleeding index were examined at baseline, 21 days, 2, 3, and 6 months. Subgingival plaque samples were collected with sterile curettes and were analyzed by real-time polymerase chain reaction for the presence of three periodontal pathogens (Porphyromonas gingivalis [P.g.], Tannerella forsythia [T.f.], and Treponema denticola [T.d.]) at baseline, 2, 3, and 6 months. Results The number of bacteria was reduced in both groups at 2 months after baseline (SRP treatment). The changes (2–6 months) in T.d. and T.f. counts in the test group were significantly lower than those in the control group. In the control group, a significant regrowth of P.g., T.f., and T.d. was observed from 2 to 6 months and of P.g. and T.f. from 3 to 6 months. On the other hand, in the test group, the number of the three bacteria did not significantly increase during the 6-month period. Conclusion The results showed that local application of minocycline, used as an adjunct to SRP, was effective for suppressing regrowth of periodontal pathogens, suggesting its risk reduction of recurrent periodontal pathogens in CP.

Proinflammatory MG-63 cells response infection with Enterococcus faecalis cps2 evaluated by the expression of TLR-2, IL-1β, and iNOS mRNA

ObjectiveWe have previously demonstrated that unencapsulated Enterococcus faecalis cps2 inhibits biofilm formation of Candida albicans, a fungus commonly found with E. faecalis in periapical lesion. In this study, we compared encapsulated and unencapsulated E. faecalis cps2 strains relationship with osteoblastic (MG-63) cells, whereas E. faecalis ATCC 29212 were used as a reference strain.ResultsThe binding capacity of E. faecalis to MG-63 cells as shown by each tested strain was comparable, but the unencapsulated strain was less invasive compared to the encapsulated and the reference strains. Moreover, quantitative real time-PCR (qPCR) results showed that infecting unencapsulated E. faecalis cps2 is a stronger stimulator for toll like receptor 2 (TLR2) and interleukin-1β (IL-1β) mRNAs, but not for inducible nitric oxide synthase (iNOS) mRNA in osteoblastic cells. In conclusion, the performance of unencapsulated E. faecalis cps2 when the bacterium interacts with osteoblastic cells is quite different from that of encapsulated E. faecalis cps2 and reference strains. It appears that the unencapsulated strain might contribute to the persistence of the periapical inflammatory response, depending on down-regulation of iNOS mRNA expression.

Biological and Immunogenicity Property of IgY Anti S. mutans ComD

Objective: This study aims to elucidate the effect of IgY anti ComD on the biological properties of Streptococcus mutans. (S. mutans) ComD is an interspecies quorum-sensing signaling receptor that plays an important role in biofilm formation by S. mutans. Materials and Methodology: Egg yolk IgY was produced by the immunization of chickens with a DNA vaccine containing the ComD DNA coding region. We evaluated the effect of the antibody on biofilm formation by S. mutans isolated from subjects with or without dental caries. We also assessed the immunoreactivity of the antibody against all isolates, and analyzed the protein profile of S. mutans by SDS-PAGE. Results: The ComD antibody was successfully induced in the hens’ eggs. It inhibited biofilm formation by all S. mutans isolates. In addition, the expression of some protein bands was affected after exposure to the antibody. Conclusion: IgY anti-S. mutans ComD reduces biofilm formation by this bacterium and alters the protein profile of S. mutans.

Mutans Streptococci counts from saliva and its protein profile in early childhood caries

Aim This study aims to analyze the number Mutans Streptococci (MS) and its protein profile from the saliva of early childhood caries (ECC) and caries-free subjects. Methods MS counts were cultured from saliva samples, and the protein profile of MS was determined from ECC and caries-free subjects. The number of colonies were counted, and the protein bands with the molecular weight of 13, 29, 39, 41.3, 74, and 95 kDa were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis method. Results We found that the number of colonies from saliva of ECC patients was higher than those caries-free (22.20 × 106 CFU/ml vs. 19.16 × 106 CFU/ml, p < 0.05). There are higher expression frequencies in protein 29, 39, 41.3, and 74 kDa of MS in ECC than caries-free subjects. Conclusions There is the higher number of MS colonies and difference of MS protein profile isolated from saliva among children with ECC and caries-free counterparts.

Ease fabrication of PCR modular chip for portable DNA detection kit

Engineering a lab-on-a-chip (LoC) to perform the DNA polymerase chain reaction (PCR) for malaria detection is the ultimate goal of this study. This paper investigates the ability to fabricate an LoC kit using conventional method to achieve the lowest production cost by using existing fabrication process. It has been known that majority of LoC was made of polydimethylsiloxane (PDMS) which in this study was realized through a contact mold process. CNC milling process was utilized to create channel features in the range of 150-250 µm on the mold. Characterization on the milling process was done to understand the shrinkage/contraction between mold to product, roughness and also angle of contact of PDMS surface. Ultimately, this paper also includes analysis on flow measurement and heat distribution of an assembled LoC PCR kit. The results show that the achieved dimension of microchannel is 227 µm wide with a roughness of 0.01 µm. The flow measurement indicates a deviation with simulation in the range of 10%. A heat distribution through the kit is achieved following the three temperature zones as desired.