Number Of Antibiotic-resistant Strains Research Articles

D-histidine combated biofilm formation and enhanced the effect of amikacin against Pseudomonas aeruginosa in vitro

Pseudomonas aeruginosa is an opportunistic gram-negative pathogenic microorganism that poses a significant challenge in clinical treatment. Antibiotics exhibit limited efficacy against mature biofilm, culminating in an increase in the number of antibiotic-resistant strains. Therefore, novel strategies are essential to enhance the effectiveness of antibiotics against Pseudomonas aeruginosa biofilms. D-histidine has been previously identified as a prospective anti-biofilm agent. However, limited attention has been directed towards its impact on Pseudomonas aeruginosa. Therefore, this study was undertaken to explore the effect of D-histidine on Pseudomonas aeruginosa in vitro. Our results demonstrated that D-histidine downregulated the mRNA expression of virulence and quorum sensing (QS)-associated genes in Pseudomonas aeruginosa PAO1 without affecting bacterial growth. Swarming and swimming motility tests revealed that D-histidine significantly reduced the motility and pathogenicity of PAO1. Moreover, crystal violet staining and confocal laser scanning microscopy demonstrated that D-histidine inhibited biofilm formation and triggered the disassembly of mature biofilms. Notably, D-histidine increased the susceptibility of PAO1 to amikacin compared to that in the amikacin-alone group. These findings underscore the efficacy of D-histidine in combating Pseudomonas aeruginosa by reducing biofilm formation and increasing biofilm disassembly. Moreover, the combination of amikacin and D-histidine induced a synergistic effect against Pseudomonas aeruginosa biofilms, suggesting the potential utility of D-histidine as a preventive strategy against biofilm-associated infections caused by Pseudomonas aeruginosa.

Antibiotics using in Georgia: clinical and epidemiological features

Background. High incidence and lethality of infectious disease is an actual problem of the 21st century medicine. Infectious diseases are one of the most common causes of morbidity worldwide. Untreatable bacterial infections with the current available antibiotics lead to increased morbidity and mortality. Antimicrobials are the most commonly prescribed drugs in the community and hospital setting. However, inappropriate use of antibiotics in recent years has particularly increased the number of antibiotic-resistant strains. Antimicrobial resistance is a significant global health threat. Without effective antimicrobials, much of the progress made in fighting infectious disease would be lost. The recent rise in resistance to these critical medicines is therefore extremely worrisome.
 Objective. To study epidemiological and clinical aspects of antibiotics using in Georgia.
 Materials and methods. The study was retrospective-prospective. We used ATC/DDD methodology for epidemiological research of antibiotic using in the country and it held 2011-2019. According to this methodology, we calculate defined daily doses of antibiotics per 1000 inhibitors (DID). The point prevalence survey was performed in 2017-2019 in Georgian hospitals for clinical research.
 Results and discussion. In last year increased antibiotic using in Georgian population. The lowest rate was in 2014 (19 DID) and the highest in 2019 (37 DID). The most commonly used antibiotics in Georgia are ceftriaxone, amoxicillin / clavulanic acid, azithromycin and ciprofloxacin. Frequency of antibiotic treatment in Georgian hospitals ranges between 77.6 % (2017) and 86.1 % (2019). The use of third generation cephalosporin ranges between 61.9 % (2017) and 59.6 % (2019). From the clinical aspects of antibiotic therapy, it is noteworthy that prevalence of antibiotic using in Georgian clinics is high and ranged from 77.6 % (2017) to 86.1 % (2019). Antibacterial prophylactic decreased and ranged from 38.3 % (2017) to 20.3 % (2019). Antibiotic selection according to guidelines on the most frequent nosology ranges between 73.8 % (2017) and 69.2 % (2019). Empirical antibiotic therapy decreased in last years and ranges between 92.2 % (2017) and 69.2 % (2019).
 Conclusions. Increasing rate of antibiotic using in Georgian population and high use of broad-spectrum antibiotics in remarkable. In hospitals, antibiotics are prescribing according to the national or intra hospital guidelines, but there prevalence rate is high. Patient histories included information about general criteria of starting antibiotic therapy. Stop or review date of antibiotic treatment after 72 h in poorly presented. We think that it is very important to continue epidemiological and clinical research for future. Also update or developed new guidelines will be perfect way for optimization.

Antibacterial Activity of Bacillus inaquosorum Strain T1 against pirABVp -Bearing Vibrio parahaemolyticus: Genetic and Physiological Characterization.

Acute hepatopancreatic necrosis disease (AHPND) is caused by PirAB toxin-producing Vibrio parahaemolyticus and has devastated the global shrimp aquaculture industry. One approach for preventing the growth of AHPND-producing Vibrio spp. is through the application of beneficial bacteria capable of inhibiting these pathogens. In this study, we focused on the inhibitory activity of Bacillus inaquosorum strain T1, which hinders V. parahaemolyticus growth in coculture experiments in a density-dependent manner; inhibition was also observed using cell-free supernatants from T1 stationary-phase cultures. Using mariner-based transposon mutagenesis, 17 mutants having a complete or partial loss of inhibitory activity were identified. Of those displaying a total loss of activity, 13 had insertions within a 42.6-kb DNA region comprising 15 genes whose deduced products were homologous to nonribosomal polypeptide synthetases (NRPSs), polyketide synthases (PKSs), and related activities, which were mapped as one transcriptional unit. Mutants with partial activity contained insertions in spo0A and oppA, indicating stationary-phase control. The levels of expression of NRPS and PKS lacZ transcriptional fusions were negligible during growth and were the highest during early stationary phase. Inactivation of sigH resulted in a loss of inhibitor activity, indicating a role for σH in transcription. Disruption of abrB resulted in NRPS and PKS gene overexpression during growth as well as enhanced growth inhibition. Our characterization of the expression and control of an NRPS-PKS gene cluster in B. inaquosorum T1 provides an understanding of the factors involved in inhibitor production, enabling this strain's development for use as a tool against AHPND-causing Vibrio pathogens in shrimp aquaculture.IMPORTANCE The shrimp aquaculture industry has been significantly impacted by acute hepatopancreatic necrosis disease (AHPND), resulting in significant financial losses annually. AHPND is caused by strains of the bacterial pathogen Vibrio parahaemolyticus, and treatment of AHPND involves the use of antibiotics, which leads to a rise in the number of antibiotic-resistant strains. Alternative treatments include the application of beneficial microorganisms having inhibitory activities against pathogens causing AHPND. In this study, we examined the ability of Bacillus inaquosorum strain T1 to inhibit the growth of an AHPND-causing Vibrio strain, and we show that this activity involves a gene cluster associated with antibacterial compound production. We found that gene expression is under stationary-phase control and that enhanced activity occurs upon inactivation of a global transition state regulator. Our approach for understanding the factors involved in producing B. inaquosorum strain T1 inhibitory activity will allow for the development of this strain as a tool for AHPND prevention and treatment.

Genome sequence of Vibrio sp. OULL4 isolated from shellfish

The members of Vibrionaceae family are Gram-negative bacterium are ubiquitous in marine and estuarine environments. This diverse group of bacteria include many pathogenic strains that potentially cause infection to humanand aquaculture animals. Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus are among the few recognized as a major, worldwide cause gastroenteritis, particularly in countries where seafood consumption is high. The control of these vibrios has been a hurdle due to the rising numbers of antibiotic resistant strains in the environments. We report the genome sequence of Vibrio sp. OULL4 isolated from shellfish. The availability of this genome sequence will facilitate the study of its antimicrobial traits, as well as add our knowledge of Vibrio sp. diversity and evolution.

Association of antimicrobial resistance and gut microbiota composition in human and non-human primates at an urban ecotourism site

BackgroundThe rise of nature-based ecotourism in the past decade has introduced unprecedented challenges in managing the increasing interaction between humans and animals. The potential transmission of antibiotic resistant microbes between humans and non-human primate populations is a concern due to their genetic similarity. Malaysia is well known for hotspots of wildlife diversity where non-human primates like monkeys and orangutans have become popular tourist attractions. In this study, we assessed the prevalence of antimicrobial resistant Staphylococcus aureus, Enterococcus species, and other Enterobacteriaceae in the faeces of human (HS) and two non-human primates (NHP) in Malaysia, the Long-tailed macaque (Macaca fascicularis, MF) and Silvered leaf monkey (Trachypithecus cristatus, TC). In addition, the faecal bacterial composition was profiled to evaluate the potential association between antibiotic resistant profiles and composition of gut microbiota.ResultsWe tested the isolated bacteria using a selection of antibiotics. The results showed that both the number of antibiotic resistant strains and resistance level were higher in humans than NHPs. Overall, the composition of gut microbiome and pattern of antibiotic resistance showed that there was higher similarity between MF and TC, the two NHPs, than with HS. In addition, samples with higher levels of antibiotic resistance showed lower bacterial richness. Homo sapiens had the lowest bacterial diversity and yet it had higher abundance of Bacteroides. In contrast, NHPs displayed higher bacterial richness and greater prevalence of Firmicutes such as Ruminococceae and Oscillospira.ConclusionHigher antibiotic susceptibility in NHPs is likely related to low direct exposure to antibiotics. The lack of resistance may also suggest limited antimicrobial resistance transmission between humans and NHP. Nonetheless, continued monitoring over a long period will help mitigate the risk of anthropozoonosis and zooanthroponosis.

Off-target effects of an insect cell-expressed influenza HA-pseudotyped Gag-VLP preparation in limiting postinfluenza Staphylococcus aureus infections

Clinical and historical data underscore the ability of influenza viruses to ally with Staphylococcus aureus and predispose the host for secondary bacterial pneumonia, which is a leading cause of influenza-associated mortality. This is fundamental because no vaccine for S. aureus is available and the number of antibiotic-resistant strains is alarmingly rising. Hence, this leaves influenza vaccination the only strategy to prevent postinfluenza staphylococcal infections. In the present work, we assessed the off-target effects of a Tnms42 insect cell-expressed BEI-treated Gag-VLP preparation expressing the HA of A/Puerto Rico/8/1934 (H1N1) in preventing S. aureus superinfection in mice pre-infected with a homologous or heterologous H1N1 viral challenge strain. Our results demonstrate that matched anti-hemagglutinin immunity elicited by a VLP preparation may suffice to prevent morbidity and mortality caused by lethal secondary bacterial infection. This effect was observed even when employing a single low antigen dose of 50 ng HA per animal. However, induction of anti-hemagglutinin immunity alone was not helpful in inhibiting heterologous viral replication and subsequent bacterial infection. Our results indicate the potential of the VLP vaccine approach in terms of immunogenicity but suggest that anti-HA immunity should not be considered as the sole preventive method for combatting influenza and postinfluenza bacterial infections.

Interactions between the Trimeric Autotransporter Adhesin EmaA and Collagen Revealed by Three-Dimensional Electron Tomography.

Bacterial adhesion to host tissues is considered the first and critical step of microbial infection. The extracellular matrix protein adhesin A (EmaA) is a collagen-binding adhesin of the periodontal pathogen Aggregatibacter actinomycetemcomitans Three 202-kDa EmaA monomers form antenna-like structures on the bacterial surface with the functional domain located at the apical end. The structure of the 30-nm functional domain has been determined by three-dimensional (3D) electron tomography and subvolume averaging. The region exhibits a complex architecture composed of three subdomains (SI to SIII) and a linker between subdomains SII and SIII. However, the molecular interaction between the adhesin receptor complexes has yet to be revealed. This study provides the first detailed 3D structure of reconstituted EmaA/collagen complexes obtained using 3D electron tomography and image processing techniques. The observed interactions of EmaA with collagen were not to whole, intact fibrils, but rather to individual collagen triple helices dissociated from the fibrils. The majority of the contacts with the EmaA functional domain encompassed subdomains SII and SIII and in some cases the tip of the apical domain, involving SI. These data suggest a multipronged mechanism for the interaction of Gram-negative bacteria with collagen.IMPORTANCE Bacterial adhesion is a crucial step for bacterial colonization and infection. In recent years, the number of antibiotic-resistant strains has dramatically increased; therefore, there is a need to search for novel antimicrobial agents. Thus, great efforts are being devoted to develop a clear understanding of the bacterial adhesion mechanism for preventing infections. In host/pathogen interactions, once repulsive forces are overcome, adhesins recognize and tightly bind to specific receptors on the host cell or tissue components. Here, we present the first 3D structure of the interaction between the collagen-binding adhesin EmaA and collagen, which is critical for the development of endocarditis in humans.

Determining the role of the pilD gene in Francisella tularensis susceptibility to resazomycins.

Antimicrobial resistant strains (AMRs) of bacteria have become such a severe worldwide issue that the United Nations General assembly met in 2016 to discuss the topic of AMRs. Due to the increase in the number of antibiotic-resistant strains, new therapeutics against AMRs must be developed. Resazomycins are resazurin-based compounds that exhibit antimicrobial activity against F. tularensis as well as other Gram-negative bacteria including N. gonorrheae. The mode of action of these antibiotics is not understood. Approximately half of forty-eight resazurin-resistant F. tularensis isolates had a mutation in the genes FTL_0959 (pilD) and FTL_1306 (dipA). The objective of this project is to determine how pilD affects F. tularensis susceptibility to resazomycins. In F. tularensis, pilD encodes for the cytoplasmic membrane peptidase responsible for processing the prepilin subunits in type IV pilin assembly proteins. We are currently working to generate a pilD null deletion mutant using standard molecular genetic techniques. We will first confirm the sensitivity of the pilD deletion mutant to resazomycins. Understanding the role of pilD in resazomycin susceptibility would facilitate further development of these compounds as potential treatments for tularemia and gonorrhea.

Systematically integrated metabonomic-proteomic studies of Escherichia coli under ciprofloxacin stress

Many antibiotics are used to kill pathogenic Escherichia coli each year, resulting in an increase in the number of antibiotic-resistant strains. In this study, an integrated metabonomic-proteomic method was performed to systematically compare the profiles of metabolites and proteins with or without ciprofloxacin (CFLX) treatment. Proteomics identified 290 altered proteins including 143 with decreased and 147 increased expression, respectively. Metabonomics identified 65 altered metabolites including 58 and 7 with decreased and increased expression, respectively. The integrated analysis showed that the CFLX inhibited the DNA replication and increased the expression of DNA gyrase and DNA topoisomerase 1, while causing a sharp decrease in metabolic activity such as the alanine, aspartate and glutamate metabolism. Moreover, CFLX affected the biosynthesis of aminoacyl- transfer RNAs (tRNAs), leading to an increase in aminoacyl-tRNAs ligases, but limited the aminoacyl-tRNAs-mediated-biosynthesis of related amino acids. In this study, we identified the metabolite and protein profiles under CFLX stress, indicating the mode of action of antibiotics in E. coli. Furthermore, the decreasing metabolic activity in E. coli may be an effective strategy to escape killing by antimicrobials or toxic compounds. The results of this study will advance our understanding of the mechanisms underlying the resistance of bacteria to antibiotics. Biological significanceTo investigate the biological impact of antibiotics stress on Escherichia coli, we applied an integrated metabonomic-proteomic method to systematically compare the profiles of metabolites and proteins between with and without antibiotics ciprofloxacin (CFLX) treatment. Following bioinformatics analysis showed that CFLX inhibited the DNA replication and increased the expression of DNA gyrase and DNA topoisomerase, while causing a sharp increase in the alanine, aspartate and glutamate metabolism. Moreover, CFLX affected the biosynthesis of tRNAs and limited the generation of related amino acids metabolites. In a summary, our results will provide the metabolite and protein profiles under CFLX stress, indicating the mode of action of antibiotics in E. coli. The results of this study will advance our understanding of the mechanisms underlying the resistance of bacteria to antibiotics.

Predictive characterization of hypothetical proteins in Staphylococcus aureus NCTC 8325.

Staphylococcus aureus is one of the most common hospital acquired infections. It colonizes immunocompromised patients and with the number of antibiotic resistant strains increasing, medicine needs new treatment options. Understanding more about the proteins this organism uses would further this goal. Hypothetical proteins are sequences thought to encode a functional protein but for which little to no evidence of that function exists. About half of the genomic proteins in reference strain S. aureus NCTC 8325 are hypothetical. Since annotation of these proteins can lead to new therapeutic targets, a high demand to characterize hypothetical proteins is present. This work examines 35 hypothetical proteins from the chromosome of S. aureus NCTC 8325. Examination includes physiochemical characterization; sequence homology; structural homology; domain recognition; structure modeling; active site depiction; predicted protein-protein interactions; protein-chemical interactions; protein localization; protein stability; and protein solubility. The examination revealed some hypothetical proteins related to virulent domains and protein-protein interactions including superoxide dismutase, O-antigen, bacterial ferric iron reductase and siderophore synthesis. Yet other hypothetical proteins appear to be metabolic or transport proteins including ABC transporters, major facilitator superfamily, S-adenosylmethionine decarboxylase, and GTPases. Progress evaluating some hypothetical proteins, particularly the smaller ones, was incomplete due to limited homology and structural information in public repositories. These data characterizing hypothetical proteins will contribute to the scientific understanding of S. aureus by identifying potential drug targets and aiding in future drug discovery.

Antimicrobial screening of free and bound flavonoid from the bark of Terminalia arjuna

Continuous use of antibiotics results in the increased number of antibiotic resistant strains of microorganisms. Thus, a diverse arsenal of new antimicrobial agents is urgently needed to combat the diminishing efficacy of existing antibiotics. Almost all parts of plants (roots, stem, leaves, flowers, fruits and seeds) have been reported to have one or the other important bioactive compound but very little has been reported from bark of the plant except for few. Present study is confined to explore bark of Terminelia arjuna for some bioactive compounds. T. arjuna bark was collected, air dried and soxhlet extracted by using standard method for flavonoid extraction. Bound and free flavonoid extracts were then screened for antimicrobial activity using Disc Diffusion Assay. MIC, MBC and TA of each extract was also calculated. Both bound and free flavonoid showed activity against all the selected pathogens but the maximum inhibition zone was observed against Agrobacterium tumifacians (IZ= 19mm, AI=1.461±0.010) & Bacillus subtilis (IZ= 16mm, AI= 1.230±0.098) by the bound and free flavonoid extract of the plant respectively. Results obtained advocates the use of bark of the selected plant for pharmaceutical purpose to combat upcoming resistant pathogens.

Evaluation of antimicrobial efficacy of methanolic extract of Cocculus hirsutus (L.) Diels

Context: The persistent increase in the number of antibiotic resistant strains of microorganisms has led to the development of more potent but more expensive antibiotics. Synthetic drugs are mostly associated with side effects and are generally costly, hence are not affordable to economically poor class of the society when long‐term treatment is required, thus interest has been developed in the use of herbal medicines which have been reported to have either very little or no side effects. Aims: Present work was carried out to assess the antimicrobial activity of crude methanolic extract of Cocculus hirsutus against some multidrug resistant pathogenic bacteria. Materials and Methods: Different plant parts of C. hirsutus were collected and air dried and soxhlet extracted using methanol as solvent. These extracts were then tested for antimicrobial activity using agar‐well diffusion method. Inhibition zone, activity index, minimum inhibitory concentration were also calculated. Statistical Analysis: Mean value and standard deviation were calculated for each test bacteria and fungus. Data were analysed by one–way ANOVA and P values were considered significant at P < 0.05. Results: Maximum Zone of inhibition was observed in the callus extracts against Staphylococcus epidermidis (3.9 ± 0.56 mm) amongst the bacteria species and against Phanerochaete chrysosporium (2.5 ± 0.63 mm) amongst the fungal species. Methanolic extracts of leaf and stem showed varied activity with a different strain of bacteria and fungi. Methanolic extract of leaf and stem showed maximum inhibition zone against Micromonospora sp. bacterial strain. In this study, methanolic extract of callus sample showed highest promising minimal inhibitory concentration of 61.1 μg/ml in S. epidermidis. Conclusion: Results of the present study reveal that methanolic extracts of C. hirsutus are showing great antimicrobial potential against tested microorganisms and may be exploited for future antimicrobial drugs. Key words: Activity index, Cocculus hirsutus, inhibition zone, methanolic extract, minimum inhibitory concentration

Protection of mice against Staphylococcus aureus infection by a recombinant protein ClfA-IsdB-Hlg as a vaccine candidate.

Staphylococcus aureus is one of the most important causes of nosocomial infections. An effective vaccine to prevent S. aureus infections is urgently required due to the dramatic increase in the number of antibiotic-resistant strains. In this report, we evaluated a newly recombinant protein composed of selected antigenic regions of clumping factor A (ClfA), iron surface determinant B (IsdB) and gamma hemolysin B (HlgB) of S. aureus and sequence coding for hydrophobic linkers between three domains. The recombinant gene was constructed in pET-28a (+) and expressed in Escherichia coli BL21. In addition, sequence coding for a His(6)-tag was added followed by a hybrid procedure of nickel chelate protein purification. Immunization of BALB/c mice with the recombinant protein ClfA-IsdB-Hlg evoked antigen-specific antibodies that could opsonize S. aureus cells, enhancing in vitro phagocytosis by macrophages. Vaccination with the recombinant protein also reduced the bacterial load recovered from mice spleen samples and increased survival following the intraperitoneal challenge with pathogenic S. aureus compared to the control mice. Our results showed that the recombinant protein ClfA-IsdB-Hlg is a promising vaccine candidate for the prevention of S. aureus bacteremia infections.

Exploration of antibacterial metabolites producing marine bacteria from Sundarbans, Bangladesh

To combat the increasing numbers of antibiotic resistant strains of pathogenic bacteria new source of antibacterial agents are desperately needed. This study was aimed to discover new marine bacteria having antibacterial activity from marine soil samples of Sundarbans, Bangladesh. Using starch-casein-nitrate-agar medium thirty nine marine bacteria colonies were isolated as pure isolates from nine marine soil samples. Each of the isolates was preserved in both short term and long term basis. Based on the aerial and substrate mycelia color of the isolates they were grouped into five color series and were screened for their antibacterial activity against a series of test bacteria. Among thirty nine pure isolates twenty four isolates (61.5%) exhibited moderate to high activity against three grampositive and four gram-negative bacteria. This is due to the antibacterial metabolites secreted in the medium by most of the isolates. It suggested that Sundarbans may be an interesting, valuable and potential source for the exploration of novel marine bacteria with the potential to yield useful new antibacterial secondary metabolites of pharmaceutical interest.Bangladesh Pharmaceutical Journal 18(1): 53-60, 2015

Assessment of the safety and immunogenicity of Rhodococcus equi-secreted proteins combined with either a liquid nanoparticle (IMS 3012) or a polymeric (PET GEL A) water-based adjuvant in adult horses and foals—Identification of promising new candidate antigens

Rhodococcus equi is the most common infectious cause of mortality in foals between 1 and 6 months of age. Because of an increase in the number of antibiotic-resistant strains, the optimization of a prophylactic strategy is a key factor in the comprehensive management of R. equi pneumonia.The objectives of this study were to assess the safety and immunogenicity of R. equi-secreted proteins (ReSP) co-administered with either the nanoparticular adjuvant Montanide™ IMS 3012 VG, or a new polymeric adjuvant Montanide™ PET GEL A, and to further investigate the most immunogenic proteins for subsequent immunization/challenge experiments in the development of a vaccine against rhodoccocal pneumonia. The approach involved two phases. The first phase aimed to investigate the safety of vaccination in six adult horses. The second phase aimed to determine the safety and immunogenicity of vaccination in twelve 3-week-old foals.We set out to develop a method based on ultrasound measurements for safety assessment in adult horses in order to evaluate any in situ changes at the injection site, in the skin or the underlying muscle, with quantitative and qualitative data revealing that administration of ReSP combined with the Pet Gel A adjuvant led to an increase in local inflammation, associated with 4- to 7-fold higher levels of anti-R. equi IgGa, IgGb and IgGT, compared to administration of ReSP associated with IMS 3012 adjuvant, but without any impact on animal demeanor. Investigations were then performed in foals with serological and clinical follow-up until 6 months of age. Interestingly, we observed in foals a much lower incidence of adverse local tissue reactions at the injection site than in adult horses, with transient and moderate swelling for the group that received ReSP combined with Pet Gel A. Immunized foals with Pet Gel A adjuvant exhibited a similar response in both IgGa and IgGT levels, but a lower response in IgGb levels, compared to adult horses, with a subisotype profile that may however reflect a bias favorable to R. equi resistance. From the crude extract of secreted proteins, dot-blot screening enabled identification of cholesterol oxidase, mycolyl transferase 3, and PSP (probable secreted protein) as the most immunogenic candidates. Taken together, these results are encouraging in developing a vaccine for foals.

Multidrug resistant commensal Escherichia coli in animals and its impact for public health.

After the era of plentiful antibiotics we are alarmed by the increasing number of antibiotic resistant strains. The genetic flexibility and adaptability of Escherichia coli to constantly changing environments allows to acquire a great number of antimicrobial resistance mechanisms. Commensal strains of E. coli as versatile residents of the lower intestine are also repeatedly challenged by antimicrobial pressures during the lifetime of their host. As a consequence, commensal strains acquire the respective resistance genes, and/or develop resistant mutants in order to survive and maintain microbial homeostasis in the lower intestinal tract. Thus, commensal E. coli strains are regarded as indicators of antimicrobial load on their hosts. This chapter provides a short historic background of the appearance and presumed origin and transfer of antimicrobial resistance genes in commensal intestinal E. coli of animals with comparative information on their pathogenic counterparts. The dynamics, development, and ways of evolution of resistance in the E. coli populations differ according to hosts, resistance mechanisms, and antimicrobial classes used. The most frequent tools of E. coli against a variety of antimicrobials are the efflux pumps and mobile resistance mechanisms carried by plasmids and/or other transferable elements. The emergence of hybrid plasmids (both resistance and virulence) among E. coli is of further concern. Co-existence and co-transfer of these “bad genes” in this huge and most versatile in vivo compartment may represent an increased public health risk in the future. Significance of multidrug resistant (MDR) commensal E. coli seem to be highest in the food animal industry, acting as reservoir for intra- and interspecific exchange and a source for spread of MDR determinants through contaminated food to humans. Thus, public health potential of MDR commensal E. coli of food animals can be a concern and needs monitoring and more molecular analysis in the future.

Evaluation of antimicrobial efficacy of flavonoids and alkaloids of Andrographis paniculata nees

Context: The persistent increase in the number of antibiotic resistant strains of microorganisms has led to the development of more potent but more expensive antibiotics. Synthetic drugs are mostly associated with side effects and are generally costly, hence are not affordable to economically poor class of the society when long term treatment is required, thus interest has been developed in the use of herbal medicines which have been reported to have either very little or no side effects. Aims: Present work was carried out to assess the antimicrobial activity of A. paniculata against some multidrug resistant pathogenic bacteria. Materials and Methods: Different parts (leaf, stem, root) of A. paniculata were collected and air dried and soxhlet extracted by using standard methods for flavonoid and alkaloid extraction. These extracts were then tested for antimicrobial activity using disc diffusion method. Minimum inhibitory concentration, Minimum bactericidal concentration and Total activity were also calculated. Statistical Analysis: Mean value and Standard Deviation were calculated for the test bacteria and fungi. Data were analysed by one‑way analysis of variance and P values were considered significant at P < 0.05. Results: C. albicans was found to be the most susceptible organism followed by P. mirabilis, S. aureus, E. coli, P. aeruginosa and A. flavus. A. niger and T. mentegrophyte were observed to be resistant as none of the tested extracts showed activity against them. Free flavonoid extract of root showed best activity against C. albicans (IZ 14 mm, MIC 0.156), whereas leaf free flavonoid extract showed maximum 21 mm inhibition zone against P. mirabilis.The range of MIC and MBC was found to be 1.25‑0.039 and 2.5‑0.078 respectively. Conclusion: Results of the present study reveal that extracts of A. paniculata are showing great antimicrobial potential against tested microorganisms, and may be exploited for future antimicrobial drugs Key words: Flavonoids, minimum inhibitory concentration, minimum bactericidal concentration and total activity

Preventing urinary tract infection: progress toward an effective Escherichia coli vaccine

Uncomplicated urinary tract infections (UTIs) are common, with nearly half of all women experiencing at least one UTI in their lifetime. This high frequency of infection results in huge annual economic costs, decreased workforce productivity and high patient morbidity. At least 80% of these infections are caused by uropathogenic Escherichia coli (UPEC). UPEC can reside side by side with commensal strains in the gastrointestinal tract and gain access to the bladder via colonization of the urethra. Antibiotics represent the current standard treatment for UTI; however, even after treatment, patients frequently suffer from recurrent infection with the same or different strains. In addition, successful long-term treatment has been complicated by a rise in both the number of antibiotic-resistant strains and the prevalence of antibiotic-resistance mechanisms. As a result, preventative approaches to UTI, such as vaccination, have been sought. This review summarizes recent advances in UPEC vaccine development and outlines future directions for the field.

Assessment of the Antimicrobial Potency of Leaf Extracts from Vitex Nugundo and Gloriosa Superba

An increase in the number of antibiotic resistant strains makes the discovery of new therapeutic agents critically important. During present study antimicrobial effects of the leaf extracts of Vitex nugundo (VN) and Gloriosa superba (GS) in combination with chloramphenicol, on Escherichia coli, Salmonella typhi, Staphlococcus aureus and Candida albicans was investigated. For this purpose, the dilution sensitivity and disc diffusion techniques were respectively applied in determining minimum inhibitory concentration (MIC) of the plant extracts, and the sensitivities of the organisms to the plant extracts and their combinations with chloramphenicol. V. nugundo and G. superba showed very high antimicrobial activity against all the test organisms. In combination, the effect of VN on E. coli and S. typhi was completely antagonized by that of GS whereas additive effect on S. aureus and C. albicans was observed, indicating that the combination of VN and GS might be effective against gram positive pathogenic organisms. The combination of either plant extract with chloramphenicol produced synergistic effect on only C. albicans. The smaller MIC of GS indicated greater effectivity than VN. It is concluded that the additive effect produced by the combination of the two plant extracts, and the synergic effect from the combination of any of the extracts with chloramphenicol, offer alternative therapy to gram positive bacterial infections and candidiasis respectively.

Efficacy of a Broad Host Range Lytic Bacteriophage Against E. coli Adhered to Urothelium

Persistent urinary tract infections (UTI) are often caused by E. coli adhered to urothelium. This type of cells is generally recognized as very tolerant to antibiotics which renders difficult the treatment of chronic UTI. This study investigates the use of lytic bacteriophages as alternative antimicrobial agents, particularly the interaction of phages with E. coli adhered to urothelium and specifically determines their efficiency against this type of cells. The bacterial adhesion to urothelium was performed varying the bacterial cell concentrations and the period and conditions (static, shaken) of adhesion. Three collection bacteriophages (T1, T4, and phiX174 like phages) were tested against clinical E. coli isolates and only one was selected for further infection experiments. Based on the lytic spectrum against clinical isolates and its ability to infect the highest number of antibiotic resistant strains, the T1-like bacteriophage was selected. This bacteriophage caused nearly a 45% reduction of the bacterial population after 2 h of treatment. This study provides evidence that bacteriophages are effective in controlling suspended and adhered cells and therefore can be a viable alternative to antibiotics to control urothelium- adhered bacteria.