Vol 12 No 1 (2020)

Original Article(s)

  • XML | PDF | downloads: 194 | views: 264 | pages: 1-10

    Background and Objectives: The re-emergence of pertussis still is being reported all over the world. Pathogen adaptation and antigenic divergence of circulating isolates from vaccine strains are the main reasons of infection resurgence. Waning immunity is also an important factor contributing to resurgence of pertussis.
    Materials and Methods: The genetic diversity and evolutionary characteristics of circulating Iranian isolates of Bordetella pertussis during February 2015 to October 2018 was investigated by pulsed-field gel electrophoresis (PFGE) and subsequently ptxA, ptxP and fim3 alleles were characterized. The next generation genome sequencing was then used to compare the genomics of ptxP1 and ptxP3 of selected isolates from PFGE dendrogram.
    Results: PFGE differentiated 62 clinical isolates and vaccine and reference strains into 19 PFGE profiles, indicating the higher level of heterogeneity in the population during 2015-2018. The predominant B. pertussis genotype harbored pertussis toxin promoter allele, ptxP3 and the expansion of ptxA1 isolates, were also observed in our population.
    Conclusion: No changes in allelic profile of predominant clone in recent years was observed but antigenic divergence between recently circulating isolates and the vaccine strain has been progressed and significantly was higher than previous studies. The comparative genomic analysis of the ptxP3 and ptxP1 isolates indicate that changes in ptxP3 genome structure including 32 unique SNPs and three unique indels may have contributed to the expansion of the ptxP3 clone. We compared ptxP3 and ptxP1 isolates in pathogenicity-associated genes and found five of them were specific for the ptxP3 isolates. The polymorphisms in pathogenicity-associated genes suggest structural adaptations for these virulence factors.

  • XML | PDF | downloads: 195 | views: 383 | pages: 11-17

    Background and Objectives: Identification of GBS serotypes provides helpful information for appropriate the development of suitable vaccines; however, no reports from Vietnam have been published. This study has been performed to find the prevalence and serotypes of group B Streptococcus isolated from vagina of pregnant women in Nghe An province, Vietnam.
    Materials and Methods: Vaginal swabs were collected from pregnant women at 35-37 weeks of gestation at the Nghe An Obstetrics and Pediatrics Hospital, Vietnam between May 2018 and July 2019. The swabs were cultured on 5% sheep blood agar for isolation of GBS. All isolates were identified using the Gram staining, CAMP test and specific PCR. GBS strains were serotyped using the multiplex PCR assays.
    Results: The prevalence of vaginal GBS colonization was 9.20% of 750 participants. Among the isolates, serotypes III (39.13%) and V (31.89%) were the most frequent, followed by serotypes Ia (11.59%), VI (11.59%), Ib (2.90%), II (1.45%) and VII (1.45%), respectively. Serotypes IV, VIII and IX were not found.
    Conclusion: The prevalence of GBS in the Nghe An province of central Vietnam was similar to reports from other parts of the world. The predominat GBS serotypes (III, V, Ia and VI) were slightly different from those previously described from other regions around the world. The high frequency of serotype VI was a notable feature of the strains from pregnant women in Vietnam.

  • XML | PDF | downloads: 170 | views: 181 | pages: 18-24

    Background and Objectives: Antibiotics prescribed for infections have diverse effects on microbiota and the pathogen Clostridium difficile (C. difficile) as the most important antibiotic-associated diarrhea. This study aims to determine the gene expression of toxins A and B at the transcription level in the sub-MIC of vancomycin (VAN), clindamycin (CLI), and ceftazidime (CAZ) alone and in combination.
    Materials and Methods: The MIC and fractional inhibitory concentration (FIC) of two C. difficile samples (a clinical isolate and ATCC 9689) were determined by microdilution and checkerboard microdilution methods, respectively. The total RNA was extracted from the medium inoculated with ~106 CFU/mL of fresh bacteria in the pre-reduced medium containing ½ MIC of antibiotics alone and ½ FIC of antibiotics in combination. Real-time PCR was performed by sybrGreen methods in triplicate, and the data were analyzed by the comparative ∆∆CT method.
    Results: All antibiotics except CAZ (alone and in combination) decreased the gene expression of toxins A and B within 24 hours. VAN and CLI reduced toxin gene expression within 24 and 48 hours. However, CAZ alone and in combination with VAN as well as CLI increased the gene expression of toxins A and B.
    Conclusion: The results confirmed toxin gene transcription and toxin production are associated with the type of isolates and antibiotics, as well as the combined form of antibiotics. This could be the reason which can explain the occurrence of C. difficile infection among patients who were treated with the third generation of cephalosporins alone and in combination with another antibiotic in the form of combinational therapy.

  • XML | PDF | downloads: 170 | views: 183 | pages: 25-31

    Background and Objectives: Bovine tuberculosis diagnosis is usually performed by various tests with specific limitations. Mycobacterium bovis culture filtrate contains antigenic proteins that could be used to improve the sensitivity of bovine tuberculosis diagnosis. The objective of this study was to identify and purify antigenic proteins from culture filtrates of M. bovis strain AN5 for use in immunological assays.
    Materials and Methods: Secreted proteins were purified from the heat-treated culture filtrate of M. bovis strain AN5. Proteins were precipitated with ammonium sulfate, fractionated by Sephadex G50 chromatography. The protein concentrations and the approximate molecular weight were determined by lowry method and 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), respectively. Immunological methods, including dot-blotting and western blotting, assessed the quality of the isolated proteins.
    Results: The quantity of antigenic proteins in the culture medium was measured at far more than 15% of the amount of proteins secreted into medium. Three main chromatographic fractions obtained and showed concentrations of proteins ranging from 14 to 60 μg/μl with molecular weights in the 10 to 180 kDa range. The purified antigens showed positive reactions to the infected cattle serum throughout dot-blotting. Western blotting revealed a total of 15 to 70 kDa molecular weight proteins.
    Conclusion: Immunoblotting analysis made it possible to detect and recognize novel antigens that are useful for bovine tuberculosis diagnosis improvement. This is significant since non-specific reactions were not observed when we utilized serum of cattle experimentally infected with M. bovis as a polyclonal antibody.

  • XML | PDF | downloads: 185 | views: 168 | pages: 32-36

    Background and Objectives: Burn wound infections have emerged as an important cause of morbidity and mortality in patients due to prolonged hospital stay. Pseudomonas aeruginosa, is the second cause of bacterial burn wound infections. Resistance mechanisms among P. aeruginosa are intrinsic or acquired. Intrinsic resistance mechanisms among P. aeruginosa isolates are inducible AmpC cephalosporinase, decrease of specific porin OprD, and overexpression of RND efflux pump. The aim of this study was detection of mutations in nalC gene in carbapenem resistant P. aeruginosa isolated from burn wounds.
    Materials and Methods: In this cross-sectional study, 180 burn-wound specimens were collected. Suspected lactose-negative colonies were identified by conventional biochemical methods. Kirby-Bauer and Etest methods were used for susceptibility testing. PCR and sequencing techniques were used for the detection of nalC mutation.
    Results: Out of 180 specimens received in the laboratory, 54 of isolates were isolated and identified as P. aeroginosa (30%). Of these isolates 20 (37%) were resistant to at least two carbapenems simultaneously. From these carbapenem resistant isolates, 19 (95%), 14 (70%), 14 (70%), 19 (95%) and 16 (80%) were resistant to imipenem, cefepime, piperacillin, ceftizoxime and gentamicin, respectively. Only 1 (2%) isolate was sensitive to all carbapenems and did not has mutation in nalC gene, 20 (37%) isolates were resistant to at least two carbapenems, and had mutations in nalC gene (Gly71►Glu and Ser209►Arg).
    Conclusion: As the results showed, mutation in efflux pump was observed in carbapenem resistant isolate and this confirmed that the indiscriminate use of antibiotics for treatment or prophylaxis can increase mutation in efflux pump.

  • XML | PDF | downloads: 207 | views: 251 | pages: 37-42

    Background and Objectives: There are many pertussis outbreaks which is mainly due to the reduction in the immunity of acellular pertussis (aP) vaccines. Therefore, there is a crucial necessity to develop a new generation of pertussis vaccine. Preceding researches have shown that Bordetella pertussis outer membrane vesicles (OMVs) have appropriate specifications, making them a suitable vaccine candidate against pertussis.
    Materials and Methods: The OMVs were separated by a new serial ultra centrifugation technique. Transmission electron microscopy (TEM) examination, SDS-PAGE, Western blotting and ELISA assay were used to characterize the OMVs.
    Results: TEM studies showed the size of the extracted OMVs at 40-200 nm. The presence of pertussis toxin, filamentous hemagglutinin, and pertactin was verified using Western blot and ELISA assay.
    Conclusion: The presented technique is a simple and effective way to obtain OMVs from Bordetella pertussis. So it can be utilized as an appropriate procedure in the development of an OMV-based vaccine against pertussis.

  • XML | PDF | downloads: 186 | views: 281 | pages: 43-51

    Background and Objectives: Plant-derived essential oils (EOs) shave many usages in health and medicine, such as antibacterial agents. The aim of this study was the improvement of antibacterial activities of two EOs using nanotechnology.
    Materials and Methods: Antibacterial activity was investigated on four important human pathogenic bacteria using the 96-well plate microdilution method, a quantitative approach. Eleven formulations were prepared using each of the EOs. Eventually, the best nanoformulation with the smallest particle size and polydispersive indices (PDI and SPAN) was selected using each EO for further investigations. Moreover, two microemulsions with similar ingredients and the same portion in comparison with two selected nanoemulsions were also prepared. Antibacterial activity of each EO was compared with its micro- and nano-emulsions.
    Results: The antibacterial efficacy of Zataria multiflora EO (ZMEO) was significantly better than Mentha piperita EO (MPEO). Besides, the antibacterial activity of nanoemulsion of ZMEO with a particle size of 129 ± 12 nm was significantly better than no- and micro-formulated forms of ZMEO. Interestingly, the efficiency of MPEO nanoemulsion (160 ± 25 nm) was also significantly better than MPEO and its micro-formulated form.
    Conclusion: Regardless of the intrinsic antibacterial property of two examined EOs, by formulating to nanoemulsion, their efficiencies were improved. Nanoemulsion of ZMEO introduced as an inexpensive, potent and green antibacterial agent.

  • XML | PDF | downloads: 187 | views: 200 | pages: 52-61

    Background and Objectives: Biofilm formed by Proteus mirabilis strains is one of the most important medical problems especially in the case of device-related urinary tract infections. This study was conducted to evaluate the bacteriocin produced by a marine isolate of Bacillus sp. Sh10, for it's in vitro inhibitory activity against pre-formed biofilm and in interference with the biofilm-forming of two biofilm-producing bacteria (P. mirabilis UCa4 and P. mirabilis UCe1).
    Materials and Methods: Sensitivity of two biofilm-producing bacteria (P. mirabilis UCa4 and P. mirabilis UCe1) to bacteriocin, was investigated in planktonic and biofilm states by cell viability and crystal violet assay, respectively. Scanning electron microscopy (SEM) was also performed to determine the effect of bacteriocin on the morphology of the cells associated with biofilm.
    Results: It was found that bacteriocin possessed bactericidal activity to biofilm-forming isolates in the planktonic state. However, bacteriocin interferes with the formation of biofilms and disrupts established biofilms. Bacteriocin reduced biofilm formation in the isolates of P. mirabilis UCa4 and P. mirabilis UCe1 with SMIC50 of 32 and 128 μg/mL, desirable SMIC50 of bacteriocin for biofilm disruption were 128 and 256 μg/mL, respectively. The SEM results indicated that bacteriocin affected the cell morphology of biofilm-associated cells.
    Conclusion: The present findings indicated that bacteriocin from Bacillus sp. Sh10 has bactericidal properties against biofilm-forming isolates of P. mirabilis UCa4 and P. mirabilis UCe1 and has the ability to inhibit the formation of biofilm and disrupt established biofilm.

  • XML | PDF | downloads: 155 | views: 200 | pages: 62-69

    Background and Objectives: Pathogenic bacterial infection is one of the factors that can cause extensive losses in poultry farming. Pathogenic bacteria that infect domestic chickens (Gallus domesticus) include Escherichia coli. This study has investigated antimicrobial compounds from probiotic bacteria isolated from the digestive tract of domestic chickens originating from Takalar Regency, South Sulawesi, Indonesia.
    Materials and Methods: Lactic acid bacteria were grown on de Man–Ragosa–Sharpe agar medium for 24 hours. The bacterial isolate with the best inhibitory power was identified as Bacillus subtilis (B. subtilis), based on 16S RNA sequences. Antimicrobial activity of the selected lactic acid bacteria was tested on the pathogenic bacteria, E. coli and Staphylococcus aureus. Using well diffusion method. In this study, in silico study was conducted to examine the structure and binding affinity of lactic acid bacteria against E. coli and S. aureus. Molecular docking experiments were performed using the PyRx 0.8 software.
    Results: This study showed that the bacteria were B. subtilis strain PATA-5. The response of inhibition of antimicrobial compounds produced by B. subtilis strain PATA-5 maximum in the stationary phase. The bactericidal properties of B. subtilis strain PATA-5 were categorized as strong against Gram-negative E. coli, i.e., 30.5 mm, when compared to Gram-positive S. aureus, i.e., 17.5 mm.
    Conclusion: B. subtilis strain PATA-5 is capable to produce natural antibiotic cyclic lipopeptides, namely surfactin.

Case Report(s)