Advances in Microbiology
Latest articles in this journal
Advances in Microbiology, Volume 11, pp 16-26; doi:10.4236/aim.2021.111002
Background: Typhoid fever is a major public health concern in developing countries. The upsurge in the occurrence of bacterial isolates that are resistant to nalidixic acid; with reduced susceptibility to ciprofloxacin in typhoidal Salmonellae constitutes a challenge to the clinician. Methods: In order to better understand the epidemiology of Salmonella infections in South India, Salmonella typhi isolates were screened from various healthcare centers. Salmonella isolates were identified by using standard phenotypic, serological, antibiotic susceptibility and molecular methods. Results: Among a total of 100 S. typhi isolates 9% were found to be multidrug resistant and 30% were nalidixic acid resistant. Isolates with reduced susceptibility to ciprofloxacin displays single base mutations in the gyrA gene. A very low rate of 1% resistance was found to ciprofloxacin. The only one isolate with ciprofloxacin MIC ≥ 4 μg/ml also showed single mutation in the QRDR of the gyrA gene in S. typhi (GenBank accession no. HQ176349-HQ176368). Conclusions: A very low rate of nalidixic acid resistance with reduced susceptibility to ciprofloxacin was observed in comparison to other endemic areas in isolates of S. typhi from Gulbarga, South India, with steadily increasing NAR S. typhi but decreasing MDR isolations over the study period. This is most likely due to an increased use of ciprofloxacin as a first line drug of choice over more traditional antimicrobial agents for the treatment of typhoid fever.
Advances in Microbiology, Volume 11, pp 37-62; doi:10.4236/aim.2021.111004
Antibiotic resistant β-lactamases are diverse and complex enzymes produced by most of the Gram-negative bacteria that are mediated by number of plasmids. The impact of these enzymes has posed a major threat to the health sectors and has challenged the available treatment options for both community and hospital acquired infections. These include the uncomplicated most severe life-threatening infections. Moreover, with resistance to the cephalosporin drugs these MDR strains exhibit co-resistance patterns with different class of antibiotics which is a cause of concern that leads to narrow the limited treatment options. It is alarming situation since there is a steep rise in MDR—Beta lactamase pathogens mainly in Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumanii and Pseudomonas aeruginosa. Currently, the clinical detection of Extended Spectrum of β-Lactamases (ESβL) and MβL producing pathogens are carried out by antibiotic sensitivity test on the guidelines of Clinical and Laboratory Standards Institute (formerly the National Committee for Clinical Laboratory Standards) since, the other methods being too expensive. The choice of antimicrobial treatment for infections should rely on the clinical data and the tests (AST) in asymptomatic and mild cases. However, this does not imply for critical infections. The last resorts of treatment for ESβL pathogens are carbapenem and nevertheless, resistances have also been reported for the same. With increasing resistance rate to the antibiotics, it’s very essential to follow the guidelines for detection, implementation of antibiotic rotation to reduce these pathogens, followed by the efficient infection control practices and strategies to avoid such outbreaks.
Advances in Microbiology, Volume 11, pp 157-164; doi:10.4236/aim.2021.113011
The diagnosis of pathogenic bacteria in severe pneumonia is difficult and the prognosis is poor. Its outcome is closely related to bacterial pathogenicity and the timeliness and pertinence of antibiotic treatment. Therefore, early diagnosis is of great significance to the prognosis of patients. Sputum examination and culture is the gold standard for the diagnosis of pathogens of severe pneumonia. However, due to the long time of bacterial culture, the early use of antibiotics, the change of bacteria species, mixed infection and other problems, the results of bacterial culture in sputum are often false negative. With the continuous application of new molecular biology techniques in clinical detection, the classification of bacteria and microorganisms has deepened from the identification of phenotypic characteristics to the classification of gene characteristics. Sequencing analysis with 16S rDNA sequencing technology has the characteristics of high sequencing flux, large amount of data obtained, short cycle, and can more comprehensively reflect the species composition of microbial community, real species distribution and abundance information. In this paper, 16S rDNA sequencing technology was used to analyze the bacterial population composition in the sputum of severe pneumonia, and to explore a new method of etiological diagnosis.
Advances in Microbiology, Volume 11, pp 181-189; doi:10.4236/aim.2021.113013
Phage display technology is a unique gene recombination expression technology, and it is also a simple and effective screening tool. Through panning, a protein or peptide with high affinity and selectivity to the target is obtained. Antibody phage display has become the first and most widely used in vitro screening technology. Phage display derivatives play an important role in the diagnosis and treatment of diseases. This article reviews the phage display system of phage display technology, the size and classification of antibody libraries and their applications, and discusses the application prospects and challenges of phage display technology. This thesis lays the foundation for the theoretical and experimental research of bacteriophages.
Advances in Microbiology, Volume 11, pp 63-74; doi:10.4236/aim.2021.112005
The ubiquitous consumption of junk foods has drastically contributed to the exponential rise in the incidence of obesity. Hence, the present study explores the therapeutic effect of selected indigenous wild bean Sphenostylis stenocarpa (Otili) and condiment fermented Parkia biglobosa (Iru) on obese rats. The rats were fed with a high fat diet for four weeks and the gut microbiota was monitored every other day throughout the period of the experiment. Then, the fecal metabolome was analysed by Gas Chromatography Mass Spectroscopy (GC-MS). Although there was a decrease in the mean weight of rats treated with fermented iru compared with those given Otili, it was not statistically significantly (p ≤ 0.05). The organisms identified from the fecal samples of the fermented Iru groups are Proteus vulgaris, Bacillus cereus and Esherichia coli while those identified from the Otili group include Escherichia coli, and Citrobacter Freundii. However, further study revealed that Otili and Iru had a similar faecal metabolome. Medium chain fatty acids, such as Decanoic acid, Octanoic acid, ethyl tetradecanoate, Hexadecanoic acid, Methyl tetradecanoate, 9-Hexadecanoic acid, Hexadecnoic acid, cis-10-Hepadecanoic acid, are the most common compounds found in this study. This suggests the fact that the associated gut microbiota from breakdown of respective food samples must have actively mediated in their roles of ameliorating the effect of obesity.
Advances in Microbiology, Volume 11, pp 75-89; doi:10.4236/aim.2021.112006
The novel SARS-CoV-2 virus is spreading very effectively and is highly contagious. The SARS-CoV-2 virus is not acting like other viruses and many various symptoms in the human body have been observed. The analysis of the SARS-CoV-2 structure in light of the functioning of the CRISPR-Cas9, Cas12a and CasX mechanism suggests that the virus is man-made through genetic modification. Vaccination currently appears to be a feasible and promising means of pandemic containment. The first vaccines have been approved even though the mechanism of action of the virus is not yet fully understood. Two of the prominent vaccines are mRNA vaccines, which use genetic engineering. It cannot be ruled out that the mRNA vaccines would negatively affect human cells as well. This paper provides an analysis of the SARS-CoV-2 virus mechanism, based on an emerging unified quantum theory called the I-Theory, which gives a deeper understanding of the concepts of entropy and negentropy in the field of health. The analyses are developed on the molecular and subatomic levels in order to demonstrate how the entropy-negentropy balance is disrupted and the effects upon infected cells. It is shown that the base and the ionized oxygen atom of the RNA phosphate group have been replaced by a hydroxyl radical. On a subatomic level, this modification results in one electron (a fermion) missing from the phosphate base. It is assumed that due to the missing fermions and resulting higher levels of entropy, SARS-CoV-2 has a very high level of repulsion force, destroying the cytoplasm. The entropic effect leads to a sort of ballooning and weakening of infected cells, and in the case of low immunity or diseased cells, creates damage to the organs and various long-term effects.
Advances in Microbiology, Volume 11, pp 90-108; doi:10.4236/aim.2021.112007
This study examined the sanitary conditions of public boreholes and hand dug wells water in relation to pathogenic bacteria isolated in water samples. To assess the suitability of drinking water, sanitary inspection of surroundings of the sources was conducted, membrane filtration technic was used to trap the microorganisms in the water sample and other standard microbiological technics were applied to check the heterotrophic plate counts, total coliforms, fecal coliforms and some pathogenic bacteria in the samples. It was observed that there were no delineated protection zones around many boreholes (61.19%) and in almost all hand dug wells; thus, hand dug wells were pruned to more contamination than boreholes. Heterotrophic plate counts of boreholes were significantly different between (p E. coli 157H in some. Risk assessment of factors contributing to water contamination showed that: pumps manipulation with feet, other sources of contamination such as wastewater dumps, within 10m were significantly associated to boreholes contamination with Salmonella spp, Staphylococcus aureuse, fecal coliform (p = 0.01); in hand dug wells, presence of latrine or septic tank soak-away within 10 m of the wells, poor depth and lack of internal lining, uncapped wells, presence of trees near the wells, animal and birds feces, were significant and associated to contamination with Salmonela spp., B. cepaceae, S. aureus E. coli 1 (p < 0.05). Generally water collection points are marked with very poor sanitary conditions and this situation may not change unless the contaminating risk factors are fixed and sanitary measures are taken.
Advances in Microbiology, Volume 11, pp 109-116; doi:10.4236/aim.2021.112008
Objective: 120 patients with severe pneumonia who were kept in the comprehensive ICU of our hospital in 2018 were selected, and 16s rDNA sequencing was performed to analyze the composition of pathogenic bacteria in the sputum of severe pneumonia. Methods: The sputum samples of patients with severe bacterial pneumonia were collected, and the diversity of pathogens in the samples was analyzed by polymerase chain reaction (PCR) amplification and high-throughput sequencing (16s rDNA PCR-DGGE). Results: Sequence showed that sputum samples contained a relatively large number of species, and there were many species that were not detected by sequencing. The dominant bacteria were Streptococcus, Sphingomonas, Corynebacterium, Denatobacteria, Aquobacteria, Acinetobacteria, Prevotella, Klebsiella, Pseudomonas, etc. Conclusion: Bacteria caused by sputum of severe bacterial pneumonia are complex and diverse, which provides new methods and ideas for individualized treatment of patients with severe pneumonia.
Advances in Microbiology, Volume 11, pp 117-143; doi:10.4236/aim.2021.112009
The present study aimed to evaluate Syzygium aromaticum (clove) plant extract, clove oil and eugenol for their antibacterial activity and their potential to eradicate bacterial biofilms alone and in combination with antibiotics. Anti-bacterial efficacy of S. aromaticum extract, clove oil and eugenol was evaluated as minimum inhibitory concentration (MIC) and subsequently sub-MICs was selected for inhibition of virulence factors against test bacterial strains. Biofilm cultivation and eradication was assayed using XTT reduction in 96-well microtiter plate. Checkerboard method was used to study the interaction between essential oils and antibiotics. Staphylococcus aureus MTCC3160, Staphylococcus epidermidis MTCC435, Staphylococcus sciuri (SC-01), Staphylococcus auricularis (SU-01) and Streptococcus mutans MTCC497 were found strong biofilm former among all the test bacterial strains. The potency of test agents was found in the order of eugenol > clove oil > S. aromaticum methanolic extract. Sub-MIC (0.5 × MIC) of clove oil and eugenol showed a significant reduction in cell surface hydrophobicity (p S. auricularis (SU-01), S. epidermidis MTCC435 and S. mutans MTCC497 compared to planktonic MIC (PMIC). Antibiotics (vancomycin and azithromycin) exhibited upto 1000-folds increased in SMIC compared to PMIC against all the test bacterial strains. Synergy was observed between eugenol and antibiotics (vancomycin/azithromycin) against all the test bacterial strains in both planktonic and sessile mode. Highest synergy was exhibited between eugenol and azithromycin in planktonic mode (FICI value 0.141). Further, microscopy also confirmed the spectacular effect of combination treatment on pre-formed S. aureus MTCC3160 and S. mutans MTCC497 biofilms. These findings highlighted the promising role of clove oil and eugenol alone and in combination on pathogenic bacterial biofilms.
Advances in Microbiology, Volume 11, pp 144-155; doi:10.4236/aim.2021.112010
Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Human-origin Lactobacillus is a preferable source of probiotic bacteria. This study screened 14 vaginal Lactobacillus strains as probiotic candidates by investigating probiotic-related cell surface characteristics including cell surface hydrophobicity (CSH), Lewis acidity/basicity, autoaggregation, and biofilm formation. Moderate to high CSH and autoaggregation, high basicity and low acidity were prevalent in the 14 tested strains. Biofilm formation varied in a large range among the 14 tested strains. CSH showed a high correlation with Lewis acidity and autoaggregation, while Lewis acidity was highly correlated with autoaggregation and biofilm formation. Four strains were selected as promising probiotic strains. This study was the first one to compare antibiotic sensitivity between biofilm-forming cells and planktonic cells of Lactobacillus species, and found that biofilm-forming cells of a L. fermentum strain had a significantly higher survival rate than planktonic cells in cefotaxime, cefmetazole and tetracycline, but were as sensitive to oxacillin and ampicillin as planktonic cells were.