Bacteria Of Clinical Importance Research Articles

Antimicrobial and Antibiofilm Activity of Highly Soluble Polypyrrole Against Methicillin-Resistant Staphylococcus aureus.

As a new promising therapeutic option, the activity of highly soluble polypyrrole (Hs-PPy), a specific formulation of a conducting polymer (polypyrrole - PPy) is evaluated against bacteria of clinical importance. The purpose was to evaluate the antimicrobial activity of Hs-PPy, alone or combined with oxacillin, as well as its antibiofilm potential against methicillin-resistant Staphylococcus aureus strains. Furthermore, the in silico inhibitory mechanism in efflux pumps was also investigated. 10 clinical isolates of MRSA and two reference strains were used. Antimicrobial activity was determined by broth microdilution, and the combination effect with oxacillin was evaluated by the checkerboard assay. The biofilm formation capacity of MRSA and the interference of Hs-PPy were evaluated. The inhibitory action of Hs-PPy on the efflux pump was evaluated in silico through molecular docking. Hs-PPy showed activity against the isolates, with inhibitory action between 62.5 and 125 μg/mL and bactericidal action at 62.5 μg/mL, as well as synergism in association with oxacillin. The isolates ranged from moderate to strong biofilm producers, and Hs-PPy interfered with the formation of this structure, but not with mature biofilm. There was no in silico interaction with the efflux protein EmrD, the closest homolog to NorA. Hs-PPy interferes with biofilm formation by MRSA, has synergistic potential, and is an efflux pump inhibitor.

Synergistic antibacterial action of the iron complex and ampicillin against Staphylococcus aureus

ObjectivesResistance to antibiotics among bacteria of clinical importance, including Staphylococcus aureus, is a serious problem worldwide and the search for alternatives is needed. Some metal complexes have antibacterial properties and when combined with antibiotics, they may increase bacterial sensitivity to antimicrobials. In this study, we synthesized the iron complex and tested it in combination with ampicillin (Fe16 + AMP) against S. aureus.MethodsAn iron complex (Fe16) was synthesized and characterized using spectroscopy methods. Confirmation of the synergistic effect between the iron complex (Fe16) and ampicillin (AMP) was performed using ζ–potential, infrared spectra and FICI index calculated from the minimum inhibitory concentration (MIC) from the checkerboard assay. Cytotoxic properties of combination Fe16 + AMP was evaluated on eukaryotic cell line. Impact of combination Fe16 + AMP on chosen genes of S. aureus were performed by Quantitative Real-Time PCR.ResultsThe MIC of Fe16 + AMP was significantly lower than that of AMP and Fe16 alone. Furthermore, the infrared spectroscopy revealed the change in the ζ–potential of Fe16 + AMP. We demonstrated the ability of Fe16 + AMP to disrupt the bacterial membrane of S. aureus and that likely allowed for better absorption of AMP. In addition, the change in gene expression of bacterial efflux pumps at the sub-inhibitory concentration of AMP suggests an insufficient import of iron into the bacterial cell. At the same time, Fe16 + AMP did not have any cytotoxic effects on keratinocytes.ConclusionsCombined Fe16 + AMP therapy demonstrated significant synergistic and antimicrobial effects against S. aureus. This study supports the potential of combination therapy and further research.

The Combination of Synoeca-MP Antimicrobial Peptide with IDR-1018 Stimulates Proliferation, Migration, and the Expression of Pro-Regenerative Genes in Both Human Skin Cell Cultures and 3D Skin Equivalents.

In skin lesions, the development of microbial infection affects the healing process, increasing morbidity and mortality rates in patients with severe burns, diabetic foot, and other types of skin injuries. Synoeca-MP is an antimicrobial peptide (AMP) that exhibits activity against several bacteria of clinical importance, but its cytotoxicity can represent a problem for its positioning as an effective antimicrobial compound. In contrast, the immunomodulatory peptide IDR-1018 presents low toxicity and a wide regenerative potential due to its ability to reduce apoptotic mRNA expression and promote skin cell proliferation. In the present study, we used human skin cells and a 3D skin equivalent models to analyze the potential of the IDR-1018 peptide to attenuate the cytotoxicity of synoeca-MP, as well as the influence of synoeca-MP/IDR-1018 combination on cell proliferation, regenerative processes, and wound repair. We found that the addition of IDR-1018 significantly improved the biological properties of synoeca-MP on skin cells without modifying its antibacterial activity against S. aureus. Likewise, in both melanocytes and keratinocytes, the treatment with synoeca-MP/IDR-1018 combination induces cell proliferation and migration, while in a 3D human skin equivalent model, it can accelerate wound reepithelization. Furthermore, treatment with this peptide combination generates an up-regulation in the expression of pro-regenerative genes in both monolayer cell cultures and in 3D skin equivalents. This data suggests that the synoeca-MP/IDR-1018 combination possesses a good profile of antimicrobial and pro-regenerative activity, opening the door to the development of new strategies for the treatment of skin lesions.

Essential Oil from Croton blanchetianus Leaves: Anticandidal Potential and Mechanisms of Action.

Antimicrobial drugs are becoming ineffective given the resistance acquired by microorganisms. As such, it is imperative to seek new antimicrobial molecules that could provide a basis for the development of new drugs. Therefore, this work aimed to evaluate the antimicrobial potential and the mechanisms of action of the essential oil extracted from leaves of Croton blanchetianus (named CbEO) on different fungi and bacteria of clinical importance in both planktonic and biofilm lifestyles. GC-MS/MS analysis revealed the presence of twenty-two different compounds in the CbEO, which were identified using the Kovats retention index. Among these, the most abundant were amorphene (20.03%), spathulenol (5%), bicyclogermacrene (1.49%), caryophyllene oxide (4.55%), and eucalyptol (5.62%). CbOE (50 µg mL-1) barely inhibited the growth of Bacillus subtilis (23%), Pseudomonas aeruginosa (27%), and Salmonella enterica (28%), and no inhibition was obtained against Enterobacter aerogenes and Klebsiella pneumoniae. Additionally, no activity against bacterial biofilm was detected. In contrast, CbEO was active against Candida species. C. albicans and C. parapsilosis were inhibited by 78 and 75%, respectively. The antibiofilm potential also was favorable against C. albicans and C. parapsilosis, inhibiting 44 and 74% of biofilm formation and reducing around 41 and 27% of the preformed biofilm, respectively. CbOE caused membrane damage and pore formation, overproduction of ROS, and apoptosis on C. albicans and C. parapsilosis cells, as well as not inducing hemolysis in human red cells. The results obtained in this work raise the possibility of using the essential oil of C. blanchetianus leaves as an alternative to fight infections caused by C. albicans and C. parapsilosis.

Bacteriological assessment of water from an Eastern Amazon river: challenges in ensuring basic sanitary coverage in riverside communities

This study aimed to analyze the water quality of a river in the Eastern Amazon and relate the results obtained with the lack of basic sanitation in the region. Two samples were collected from strategic points of the river and were submitted to the collimetry technique with multiple tubes to calculate the most probable number (MPN) of thermotolerant coliforms present in the water. The samples were then seeded on CLED and Hektoen agar and analyzed in a mass spectrophotometer for final identification of microorganisms. A high number of thermotolerant coliforms was detected, in addition to bacteria of clinical importance, such as Pseudomonas aeruginosa, Shigella spp. and Cronobacter sakazakii. The lack of basic sanitation in the community surrounding the river is the main cause for the significant number of thermotolerant coliforms, demonstrated by the discrepancy in the MPN between samples 1 and 2. The difficulties in guaranteeing basic sanitation in the Amazon are highlighted and the need to implement public policies and carry out health surveillance studies in these populations is reinforced.

Microbial Contamination and Antimicrobial Resistance Profiles Indicate Potential Risks of Infection at the Veterinary Medical Teaching Hospital - UFRGS, Porto Alegre, Brazil

Background: This study aimed to assess the level of bacterial contamination in the Small Animals Sector of the Veterinary Medical Teaching Hospital (HCV) of the Universidade Federal do Rio Grande do Sul (UFRGS). Firstly, a committee was invited to complete a questionnaire and to list critical sample sites for collection. With the identification of the places to be sampled, collections were made with sterile swabs on different surfaces of environments of the Veterinary Hospital. The identification of important bacteria in the veterinary area, in the different sampled environments, raises the concern for hygiene procedures in the veterinary hospital environment.Materials, Methods & Results: Sixteen samples were collected from these different areas, and microbiological analyses were performed. Standard counts of viable and strictly aerobic mesophilic microorganisms were realized. Collections were made to assess ambient air quality. With the microbiological analysis performed, bacteria of clinical importance were identified. To assess the resistance profile of the bacteria, the susceptibility test to antimicrobials was performed. MALDI-TOF/MS measurement identified 29 bacteria at the genus level and 10 bacteria at the species level and the antimicrobial susceptibility test was realized. Most of the isolates identified (60%) were bacteria of the genus Staphylococcus spp. Regarding antimicrobial susceptibility analysis the 10 bacteria identified at the species level were assessed. Test results showed that the isolates S. aureus, S. epidermidis and S. haemolyticus - collected from treatment room 2 - and S. haemolyticus, which had been isolated from samples from treatment room 2 of the cattery, presented multiresistance. Pantoea ananatis isolates from room 5 also showed a multiresistant profile for erythromycin, cephalothin, vancomycin and ampicillin. Micrococcus luteus isolates from the x-ray room and the kennel showed resistance to ceftazidime. Staphylococcus equorum isolates from room 4 were sensitive to all tested antimicrobials. Discussion: In Brazilian legislation there are no official microbiological parameters for surfaces in a veterinary hospital environment. The microorganisms present in the air are transient and variable, and the number and types of airborne agents is determined by the various sources of contamination in the environment. These microorganisms can be found in suspension, particulate matter and water droplets. Veterinary medical care tables are potentially contaminated by the animals handling, including those that sometimes defecate or urinate during their medical visit. Frequent handwashing is also known to be an important means of personal protection and disease prevention, although it is estimated that only 40% of practitioners do so routinely. Based on these results, we recommend a plan of bacterial control and disinfection that should be implemented to ensure more effective sanitary conditions. Microorganism counts were high in some of the veterinary hospital environments tested, indicating that current disinfection and hygiene practices are not sufficient to control the establishment of these microorganisms at the study sites. In view of this, it is reasonable to conclude that permanent monitoring and assessment of the effectiveness of hygiene protocols is needed in different sectors of the hospital. This may be an essential tool in a preventive approach to stop the spread of selectively resistant microorganisms, as well as cases of hospital infections. In addition, continuous staff training and awareness of the importance of personal and environmental hygiene is vital for minimizing the presence of these microorganisms in hospitals and avoid their transmission to patients. Finally, a more systematic hygiene guideline should be implemented in areas that showed higher counts.

Geospatial epidemiology of Staphylococcus aureus in a tropical setting: an enabling digital surveillance platform

Delivery of information to clinicians on evolving antimicrobial susceptibility needs to be accurate for the local needs, up-to-date and readily available at point of care. In northern Australia, bacterial infection rates are high but resistance to first- and second-line antibiotics is poorly described and currently-available datasets exclude primary healthcare data. We aimed to develop an online geospatial and interactive platform for aggregating, analysing and disseminating data on regional bacterial pathogen susceptibility. We report the epidemiology of Staphylococcus aureus as an example of the power of digital platforms to tackle the growing spread of antimicrobial resistance in a high-burden, geographically-sparse region and beyond. We developed an online geospatial platform called HOTspots that visualises antimicrobial susceptibility patterns and temporal trends. Data on clinically-important bacteria and their antibiotic susceptibility profiles were sought from retrospectively identified clinical specimens submitted to three participating pathology providers (96 unique tertiary and primary healthcare centres, n = 1,006,238 tests) between January 2008 and December 2017. Here we present data on S. aureus only. Data were available on specimen type, date and location of collection. Regions from the Australian Bureau of Statistics were used to provide spatial localisation. The online platform provides an engaging visual representation of spatial heterogeneity, demonstrating striking geographical variation in S. aureus susceptibility across northern Australia. Methicillin resistance rates vary from 46% in the west to 26% in the east. Plots generated by the platform show temporal trends in proportions of S. aureus resistant to methicillin and other antimicrobials across the three jurisdictions of northern Australia. A quarter of all, and up to 35% of methicillin-resistant S. aureus (MRSA) blood isolates in parts of the northern Australia were resistant to inducible-clindamycin. Clindamycin resistance rates in MRSA are worryingly high in regions of northern Australia and are a local impediment to empirical use of this agent for community MRSA. Visualising routinely collected laboratory data with digital platforms, allows clinicians, public health physicians and guideline developers to monitor and respond to antimicrobial resistance in a timely manner. Deployment of this platform into clinical practice supports national and global efforts to innovate traditional disease surveillance systems with the use of digital technology and to provide practical solutions to reducing the threat of antimicrobial resistance.

Interaction of Ziziphus mucronata subsp. mucronata Methanol Extract and First-Line Antibiotics is Synergistic In Vitro through Production of Reactive Oxygen Species.

With the increased incidence of antibacterial resistance in microorganisms, combining natural products from plants with antibiotics may be considered interesting alternatives for synergy to attain multitarget effects. In this study, the antioxidant activity of the methanol extract of Ziziphus mucronata and its interactions with antibiotics against bacteria of clinical importance were investigated. While its phytochemicals and antioxidant activities were determined by free radical scavenging assays, the antibacterial activities of the extract and its interactions with the antibiotics were determined by macrobroth dilution and the checkerboard methods. From the results, total phenolic content was 29.67 ± 1.90 mg GAE/100 g, total flavonoid content was 8.72 ± 0.08 mg QE/100 g, and total proanthocyanidin content was 1.94 ± 0.00 mg CE/100 g of dry plant material. The inhibition concentration 50% (IC50) of DPPH, BHT, and ascorbic acid was equal to 0.04 ± 0.02 mg/ml, respectively. Those of the ABTS, BHT, and ascorbic acid were equal to 0.02 ± 0.02, 0.04 ± 0.03, and 0.04 ± 0.02 mg/ml, respectively. The checkerboard assay showed that combining the extract with different antibiotics resulted in synergistic (38.75%), indifferent (30%), additive (28.75%), and antagonistic (2.5%) interactions. The interactions between the extract and antibiotics resulting in enhanced antibacterial activities could have resulted from the antioxidant activities of the extract mopping up the ROS generated by the antibiotics or the ability of both extract and antibiotics simultaneously producing reactive oxygen species with deleterious effects resulting in synergistic antibacterial effects.

Incidence and molecular characterization of multidrug resistance in Gram‐negative bacteria of clinical importance from pharmaceutical wastewaters in South‐western Nigeria

AbstractBackgroundThe occurrence of antimicrobial resistant bacteria in the environment presents a major threat to public health because it reduces the effectiveness of antimicrobial treatment.AimsThe study was set out to molecularly characterize Gram‐negative bacteria with multidrug resistance and resistance determinants from pharmaceutical wastewaters in Nigeria.Materials and MethodsSusceptibility of the bacterial isolates to 25 antibiotics belonging to 10 categories was tested using the disc diffusion method and Vitek 2. Screening for AmpC, Extended Spectrum Beta‐lactamase and carbapenemase production was done by Polymerase Chain Reaction and sequencing.ResultsNinety‐seven Gram‐negative bacteria, comprising 27 Enterobacteria and 70 nonfermenter bacterial isolates were detected. Antibiotic resistance observed was highest (70.1%) for sulfamethoxazole / trimethoprim and multidrug resistance was revealed in 17 bacterial strains (Klebsiella pneumoniae [7], Enterobacter gergoviae [3], Sphingomonas paucimobilis [1], Empedobacter brevis [1], Chryseobacterium indologenes [1], Pseudomonas aeruginosa [1], Burkholderia cenocepacia [1], Burkholderia cepacia and Stenotrophomonas maltophilia [1]). Extended Spectrum Beta‐lactamase (CTX‐M‐15, SHV‐12, SHV‐2) was positive for 6 K. pneumoniae strains; there were neither AmpC detected nor the production of carbapenamase in all isolates tested.DiscussionThe study confirmed the presence of multidrug resistant Gram‐negative bacteria with resistance determinants in wastewaters from pharmaceutical industries in Nigeria. Compounds of the wastewater may directly select or co‐select these multidrug resistance strains.ConclusionThe output of drug resistant bacteria into the environment is a potential risk to public health and may facilitate the spread of resistant genes.

<b> Antibacterial activity of Aroeira honeys produced in Minas-Gerais against bacteria of clinical importance

The biological activity of honey has been the subject of great scientific investigation. Bee products are widely used in folk medicine to treat human diseases due to their antibacterial and inhibitory potential action on different human pathogens. Ten honey samples produced by Apis mellifera in the northern of Minas Gerais state were tested against pathogenic microorganisms Staphylococcus aureus TSST (clinical isolated) and enterohaemorrhagic Escherichia coli ATCC 43895 for determination of their minimum inhibitory concentrations. The microdilution technique in broth Mueller-Hinton broth (MHB) was used in four concentrations (25, 12.5, 6.25 and 3.125%). There was a reduction of bacterial growth for the two target species at all concentrations tested. The optimal concentration for inhibition of S. aureus and E. coli were 3.125% (w/v). Therefore, the antibacterial activity of the tested samples evidences the potential of Aroeira honey produced in the north of Minas Gerais for therapeutic use, thus contributing to the aggregation value and commercialization of this type of honey.

Actividad antibacteriana de diatomeas marinas aisladas de Acapulco, Guerrero, México

Las diatomeas marinas sintetizan y secretan una gran variedad de metabolitos secundarios con aplicaciones potenciales en la industria farmacéutica, sin embargo su estudio aún es limitado. Por tal motivo, el objetivo de este trabajo fue aislar y cultivar las especies Chaetoceros curvisetus, Asterionella japonica, y Biddulphia mobiliensis de la Bahía Santa Lucía del Puerto de Acapulco, Guerrero, México, así como determinar la actividad antibacteriana frente a bacterias de importancia clínica y analizar el perfil fitoquímico cualitativo de sus extractos totales. La biomasa fue de 219,62 ± 0,99; 151,12 ± 1,41 y 109,04 ± 1,48 mg para C. curvisetus, A. japonica, y B. mobiliensis, respectivamente. Extractos con hexano, diclorometano, y acetona fueron obtenidos de cada especie, y el perfil fitoquímico cualitativo indicó que estas diatomeas marinas fueron ricas en aceites esenciales, alcaloides, y terpenos. Se observó que los extractos de C. curvisetus poseen alta actividad con Concentraciones Mínimas Inhibitorias (CMI) entre 0,5 y 2 mg mL-1 para bacterias tipo ATCC y de 8 y 16 mg mL-1 para cepas de E. coli productoras de BLEE.

Distribution, genetic diversity and antimicrobial resistance of clinically important bacteria from the environment of a tertiary hospital in Malaysia.

Hospital environments are potential reservoirs of bacteria associated with nosocomial infections. In this study, the distribution of cultivable environmental bacteria of clinical importance from a Malaysian tertiary hospital was determined and their resistotypes and genotypes were investigated. Swab and fluid samples (n=358) from healthcare workers' hands, frequently touched surfaces, medical equipment, patients' immediate surroundings, ward sinks and toilets, and solutions or fluids of 12 selected wards were collected. Biochemical tests, PCR and 16S rRNA sequencing were used for identification following isolation from CHROMagar™ Orientation medium. Clinically important bacteria such as Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter spp., Pseudomonas aeruginosa and Enterobacter spp. were further characterised by disc diffusion method and rep-PCR. The 24 Gram-negative and 19 Gram-positive bacteria species identified were widely distributed in the hospital environment. Staphylococci were predominant, followed by Bacillus spp. and P. aeruginosa. Frequently touched surfaces, medical equipment, and ward sinks and toilets were the top three sources of bacterial species. Nine S. aureus, four Acinetobacter spp., one K. pneumoniae and one Enterobacter spp. were multidrug-resistant (MDR). The ESKAPE organisms were genetically diverse and widely dispersed across the hospital wards. A MDR MRSA clone was detected in a surgical ward isolation room. The large variety of cultivable, clinically important bacteria, especially the genetically related MDR S. aureus, K. pneumoniae, Acinetobacter spp. and Enterobacter spp., from various sampling sites indicated that the surfaces and fomites in the hospital were potential exogenous sources of nosocomial infection in the hospital.

The In-Feed Antibiotic Carbadox Induces Phage Gene Transcription in the Swine Gut Microbiome.

ABSTRACTCarbadox is a quinoxaline-di-N-oxide antibiotic fed to over 40% of young pigs in the United States that has been shown to induce phage DNA transduction in vitro; however, the effects of carbadox on swine microbiome functions are poorly understood. We investigated the in vivo longitudinal effects of carbadox on swine gut microbial gene expression (fecal metatranscriptome) and phage population dynamics (fecal dsDNA viromes). Microbial metagenome, transcriptome, and virome sequences were annotated for taxonomic inference and gene function by using FIGfam (isofunctional homolog sequences) and SEED subsystems databases. When the beta diversities of microbial FIGfam annotations were compared, the control and carbadox communities were distinct 2 days after carbadox introduction. This effect was driven by carbadox-associated lower expression of FIGfams (n = 66) related to microbial respiration, carbohydrate utilization, and RNA metabolism (q < 0.1), suggesting bacteriostatic or bactericidal effects within certain populations. Interestingly, carbadox treatment caused greater expression of FIGfams related to all stages of the phage lytic cycle 2 days following the introduction of carbadox (q ≤0.07), suggesting the carbadox-mediated induction of prophages and phage DNA recombination. These effects were diminished by 7 days of continuous carbadox in the feed, suggesting an acute impact. Additionally, the viromes included a few genes that encoded resistance to tetracycline, aminoglycoside, and beta-lactam antibiotics but these did not change in frequency over time or with treatment. The results show decreased bacterial growth and metabolism, prophage induction, and potential transduction of bacterial fitness genes in swine gut bacterial communities as a result of carbadox administration.

Effects and time-kill assessment of amoxicillin used in combination with chloramphenicol against bacteria of clinical importance.

With the emergence of multidrug-resistant organisms in an era when drug development faces challenges causing pharmaceutical companies to curtail or abandon research on anti-infective agents, the use of combined existing antimicrobial agents may be an alternative. This study evaluated the effects of combining amoxicillin and chloramphenicol, to which many bacteria have become resistant, in vitro against Gram positive and Gram negative bacteria by agar diffusion, checkerboard and time-kill assays. The test isolates were susceptible to amoxicillin with minimum inhibitory concentrations (MICs) ranging between 0.448 and 500 µg/ml and between 1.953 and 31.25 µg/ml for chloramphenicol. Upon combining these agents, there was a drastic reduction in their MICs indicating an increased antibacterial activity that showed synergistic interaction against all the bacteria. At the highest concentrations, the inhibition zones ranges were 20.33-38.33±0.58 µg/ml for amoxicillin, 27.67-37.67±0.58 µg/ml for chloramphenicol and 31.67-39.33±0.58 µg/ml for the combined agents. The fractional inhibitory concentration indices (FICIs) showed synergy ranging from 0.129 to 0.312 while FICIs for additive interaction were between 0.688 and 1.0. There was no antagonistic interaction. At the 1/2MICs of the combined antibiotics, all the tested bacteria, except for Klebsiella pneumoniae ATCC 4352, Proteus vulgaris CSIR 0030 and Enterococcus cloacae ATCC 13047 were eliminated before 24 h. At the MICs, all the tested bacteria were eliminated except Enterococcus cloacae ATCC 13047 which was almost totally eliminated. Post-antibiotic assessment after 48 h showed that all the cultures were sterile except for that of Enterococcus cloacae ATCC 13047. The lack of antagonism between these antibacterial agents in checkerboard and time-kill assays suggested that combining amoxicillin with chloramphenicol can provide an improved therapy in comparison to the use of each antibiotic individually. The study indicates the potential beneficial value of combining amoxicillin and chloramphenicol in the treatment of microbial infections in clinical settings.

Antibacterial Activity of Desert Truffles from Saudi Arabia Against Staphylococcus aureus and Pseudomonas aeruginosa.

Medicinal mushrooms represent an unlimited source of polysaccharides with nutritional, antitumoral, antibacterial, and immune-stimulating properties. Traditional studies of epigeous higher Basidiomycetes have recently been joined by studies of hypogeous fungi and, in particular, of so-called desert truffles. With the aim to obtain novel agents against bacteria of clinical importance, we focused on the edible desert truffle mushrooms Tirmania pinoyi, Terfezia claveryi, and Picoa juniperi as sources of new antimicrobial agents. In particular, we investigated the in vitro antibacterial activity of acid-soluble protein extracts (aqueous extracts) of these 3 species against the Gram-positive human pathogenic reference strain Staphylococcus aureus ATCC 29213 and the Gram-negative strain Pseudomonas aeruginosa ATCC 15442. The acid-soluble protein extracts of T. pinoyi and T. claveryi showed minimum inhibitory concentrations of 50 μg/mL against tested pathogens. We believe that such preliminary results are promising to obtain a valuable antibiotic alternative to fight antibiotic-resistant pathogens.

Ocimum basilicum: Antibacterial activity and association study with antibiotics against bacteria of clinical importance

Context: Ocimum basilicum L. (Lamiaceae), popularly known as basil, is part of a group of medicinal plants widely used in cooking and known for its beneficial health properties, possessing significant antioxidant effects, antinociceptive, and others.Objective: The objective of this study is to determine the pharmacological effects produced on the bacterial strains Staphylococcus aureus and Pseudomonas aeruginosa when standard antibiotics and O. basilicum essential oil are combined.Materials and methods: The extraction of O. basilicum (leaves) components was done by steam distillation. The Minimum inhibitory concentration (MIC) was calculated using microdilution technique, where the oil concentrations varied from 2 to 1024 μg/mL. The combinations of O. basilicum oil with ciprofloxacin or imipenem were analyzed by the checkerboard method where fractional inhibitory concentration (FIC) indices were calculated.Results: Ocimum basilicum essential oil, imipenem, and ciprofloxacin showed respective MIC antibacterial activities of 1024, 4, and 2 μg/mL, against S. aureus. In S. aureus, the oil with imipenem association showed synergistic effect (FIC = 0.0625), while the oil with ciprofloxacin showed antagonism (FIC value = 4.25). In P. aeruginosa, the imipenem/oil association showed additive effect for ATCC strains, and synergism for the clinical strain (FIC values = 0.75 and 0.0625). The association of O. basilicum essential oil with ciprofloxacin showed synergism for clinical strains (FIC value = 0.09).Conclusion: Ocimum basilicum essential oil associated with existing standard antibiotics may increase their antibacterial activity, resulting in a synergistic activity against bacterial strains of clinical importance. The antibacterial activity of O. basilicum essential oil may be associated with linalool.

Structural Diversity of Class 1 Integrons in Multiresistant Strains of Escherichia coli Isolated from Patients in a Hospital in Mexico City.

Since a decade, Escherichia coli has been considered an important nosocomial pathogen due to the high number of isolates multiresistant to antimicrobials reported worldwide. In clinical and environmental strains, transposons, plasmids, and integrons are currently considered the principal genetic elements responsible for the acquisition of antibiotic resistance through horizontal transfer. The objective of this research was to correlate the resistance to antibiotics of E. coli clinical strains with the presence class I integrons. In the present study, one hundred E. coli strains were isolated and tested for susceptibility and resistance to antimicrobials. Class 1 integrons were detected by PCR, and the arrangement of gene cassettes was determined by sequencing. Twenty two strains were found to carry Class 1 integrons. Sequence analysis of the variable regions revealed the presence of several gene cassettes, such as dihydrofolate reductases (dfr2d, dfrA17, and dhfrXVb), adenylyl transferases (aadA2, addA5, and addA22), and chloramphenicol efflux pump (cmlA), and oxacillinase (bla OXA-1 ). The dfrA17-addA5 arrangement prevailed upon other integrons in the study. This is the first report of the presence of the dfr2d and dhfrXVb-aadA2 cassette arrangements in a Class 1 integrons from clinical strains of E. coli. In most of the strains, it was found a direct relationship between genetic arrangements and resistance phenotypes. Four integrons were detected in plasmids that might be involved in the resistance genes transfer to other bacteria of clinical importance. Our results confirm the presence of Class 1 integrons and their essential role in the dissemination of resistance cassettes among E. coli strains.

White and blue light induce reduction in susceptibility to minocycline and tigecycline in Acinetobacter spp. and other bacteria of clinical importance.

Minocycline (MIN) and tigecycline (TIG) are antibiotics currently used for treatment of multidrug-resistant nosocomial pathogens. In this work, we show that blue light, as well as white light, modulates susceptibility to these antibiotics in a temperature-dependent manner. The modulation of susceptibility by light depends on the content of iron; an increase in iron results in a reduction in antibiotic susceptibility both under light and in the dark, though the effect is more pronounced in the latter condition. We further provide insights into the mechanism by showing that reduction in susceptibility to MIN and TIG induced by light is likely triggered by the generation of (1)O2, which, by a yet unknown mechanism, would ultimately lead to the activation of resistance genes such as those coding for the efflux pump AdeABC. The clinical relevance of these results may lie in surface-exposed wound infections, given the exposure to light in addition to the relatively low temperatures recorded in this type of lesion. We further show that the modulation of antibiotic susceptibility occurs not only in Acinetobacter baumannii but also in other micro-organisms of clinical relevance such as Escherichia coli and Staphylococcus aureus. Overall, our findings allow us to suggest that MIN and TIG antibiotic treatments may be improved by the inclusion of an iron chelator, in addition to keeping the wounds in the dark, a condition that would increase the effectiveness in the control of infections involving these micro-organisms.

Probabilistic latent semantic analysis applied to whole bacterial genomes identifies common genomic features.

The spread of drug resistance amongst clinically-important bacteria is a serious, and growing, problem [1]. However, the analysis of entire genomes requires considerable computational effort, usually including the assembly of the genome and subsequent identification of genes known to be important in pathology. An alternative approach is to use computational algorithms to identify genomic differences between pathogenic and non-pathogenic bacteria, even without knowing the biological meaning of those differences. To overcome this problem, a range of techniques for dimensionality reduction have been developed. One such approach is known as latent-variable models [2]. In latent-variable models dimensionality reduction is achieved by representing a high-dimensional data by a few hidden or latent variables, which are not directly observed but inferred from the observed variables present in the model. Probabilistic Latent Semantic Indexing (PLSA) is an extention of LSA [3]. PLSA is based on a mixture decomposition derived from a latent class model. The main objective of the algorithm, as in LSA, is to represent high-dimensional co-occurrence information in a lower-dimensional way in order to discover the hidden semantic structure of the data using a probabilistic framework. In this work we applied the PLSA approach to analyse the common genomic features in methicillin resistant Staphylococcus aureus, using tokens derived from amino acid sequences rather than DNA. We characterised genome-scale amino acid sequences in terms of their components, and then investigated the relationships between genomes and tokens and the phenotypes they generated. As a control we used the non-pathogenic model Gram-positive bacterium Bacillus subtilis.

Probabilistic Latent Semantic Analysis Applied to Whole Bacterial Genomes Identifies Common Genomic Features

Summary The spread of drug resistance amongst clinically-important bacteria is a serious, and growing, problem [1]. However, the analysis of entire genomes requires considerable computational effort, usually including the assembly of the genome and subsequent identification of genes known to be important in pathology. An alternative approach is to use computational algorithms to identify genomic differences between pathogenic and non-pathogenic bacteria, even without knowing the biological meaning of those differences. To overcome this problem, a range of techniques for dimensionality reduction have been developed. One such approach is known as latent-variable models [2]. In latent-variable models dimensionality reduction is achieved by representing a high-dimensional data by a few hidden or latent variables, which are not directly observed but inferred from the observed variables present in the model. Probabilistic Latent Semantic Indexing (PLSA) is an extention of LSA [3]. PLSA is based on a mixture decomposition derived from a latent class model. The main objective of the algorithm, as in LSA, is to represent high-dimensional co-occurrence information in a lower-dimensional way in order to discover the hidden semantic structure of the data using a probabilistic framework. In this work we applied the PLSA approach to analyse the common genomic features in methicillin resistant Staphylococcus aureus, using tokens derived from amino acid sequences rather than DNA. We characterised genome-scale amino acid sequences in terms of their components, and then investigated the relationships between genomes and tokens and the phenotypes they generated. As a control we used the non-pathogenic model Gram-positive bacterium Bacillus subtilis.