Staphylococcus aureus and Pseudomonas aeruginosa are the major globally distributed pathogens, which causes chronic and recalcitrant infections due to their capacity to produce biofilms in large part. Biofilm production represents a survival strategy in these species, allowing them to endure environmental stress by altering their gene expression to match their own survival needs. In this study, we co-cultured different clinical isolates of S. aureus and P. aeruginosa as mono- and mixed-species biofilms in a full-strength Brain Heart Infusion Broth (BHI) and in a 1000-fold diluted Brain Heart Infusion Broth (BHI/1000) using Microtiter plate assay and determination of colony-forming units. Furthermore, the effect of starvation stress on the expression of pslA and fnbA genes of both species was investigated using RT-PCR. This work indicated that starvation stress significantly increased the biofilm biomass and bacterial density in all mono and mixed biofilm-producing strains. Interestingly, co-culture biofilms exhibited higher resistance to starvation as compared to monoculture. The current results also showed that the expression of fnbA and pslA genes was up-regulated under starvation stress in mono-and coculture biofilm. meanwhile, up-regulates of both genes in co-culture biofilm was significantly higher than mono- species biofilm.
The spread of antibiotic resistant bacteria is a worldwide problem. Due to the importance of P. aeruginosa as a multidrug resistant bacterium, this study aimed, through molecular techniques, to detect point mutations in chromosomal genes responsible for the quinolones class of antibiotics resistance. A total of 52 isolates from burn infections were identified using specific primers for P. aeruginosa 16S rDNA. Ciprofloxacin minimum inhibitory concentrations (MIC) were estimated using the agar dilution assay. DNA sequences of the quinolone resistance-determining regions of gyrA and parC were determined for detecting the mutations found in these genes and the relations among the i
... Show MoreDue to its various resistance mechanisms, Pseudomonas aeruginosa is the most prevalent opportunistic infection that kills hospitalized patients. Thus, therapeutic options become limited. Objective: The study aimed to estimate the antibiofilm effectiveness of Conocarpus erectus leaf extracts against MDR P. aeruginosa isolates and examines pelA and algD gene expression. Subjects and Methods: One hundred-fifty clinical samples were collected from five Baghdad hospitals between September 2021 and January 2022. Samples were grown on different mediums. Despite cetrimide agar's ability to detect P. aeruginosa, only 83 isolates developed at 42°C. VITEK 2 compact system identification followed. This study examined 83 of P. aeruginosa isolates for r
... Show MoreThis study concerns the isolation of oil degraded bacterial samples from oil polluted soil in Al-Dora refinery/ Baghdad – Iraq. Soil samples (15) were on mineral salt agar medium (MSM) used to screen the oil degrading bacteria by forming clear zones around the colonies. To confirm the degradation of oil by these bacteria, the isolates were inoculated in mineral salt broth, 15 isolates of Pseudomonas spp. was detected from which two isolates identified as P. aeruginosa by morphological, physical and biochemical characteristics that confirmed by using Vitick identification system. Growth was estimated in terms of whole cell by measuring optical density at 620 nm and free extract protein was estimated by protein measurement with Folin phe
... Show MoreOne of the most causative agents for many opportunistic diseases is the Pseudomonas aeruginosa which has a high percentage of multidrug resistance disease through construction of biofilm. The current study aimed for evaluating the correlation between quorum sensing genes (which is lasI gene) and biofilm formation. The biofilm construction and antibiotics susceptibility test were achieved for all the isolates under the study. The PCR and sequencing techniques were also carried out to detect the type of variation in lasI gene for each scheme of biofilm formation (weak, strong, and moderate). High antibiotic resistance was recorded among biofilm producing isolates. The genic pattern for the weak biof
... Show MorePseudomonas aeruginosa is an opportunistic pathogen. Quorum sensing (QS) is one of processes that are responsible for biofilm formation. P. aeruginosa can live in different environments, some of which are pathogenic (clinical isolates) and some that are found outside the body (environmental isolates). The present study aimed to determine the presence of a number of genes responsible for QS in clinical and environmental isolates of P. aeruginosa. In the present study full DNA was separated from all environmental and clinical isolates that contained seven genes (rhlA, rhlR, rhlI, lasR, lasI, lasB, phzA1) associated with QS occurrence. The tot
... Show MoreThe microbial production of substances that have the ability to inhibit the growth of other microorganisms is possibly the most common defense strategy developed in nature. Microorganisms produce a variable collection of microbial defense systems, which include antibiotics, metabolic by-products, lytic agents, bacteriocins and others. The aim of the present study was to isolate and identify Enterococcus spp. and its most prevalent species from food samples and determine its antibacterial activity against Staphylococcus aureus isolates. A total of 50 food samples from different sources (dairy products (20 samples) and vegetables and fish (15 samples each)) were collected from different local markets in Baghdad and
... Show MoreThe ability of single and mixed bacterial culture to utilize Dora-refineries petroleum wastes was compared. Pseudomonas aeruginosa and Serratia ficaria mixed culture consumed the wastes better than the single bacterial cultures. The highest log. number of viable cells in mixed culture was 6.842 , while in single bacterial cultures it was 6.683 and 5.631, respectively. after 3 days in API medium containing the refinery wastes. The effect of some environmental conditions on the degradation of petroleum wastes was studied included aeration , NaCl concentration , pH and temperature. The growth of bacteria in the agitated culture was higher than stagnant culture the log. of cell no. was 6.021 in the first culture. The h
... Show MoreThe present study was undertaken in order to investigate the role of gentamicin in the gene expression of toxA in Pseudomonas aeruginosa isolated from cow mastitis. A total of ten P. aeruginosa strains originally isolated from cows infected with mastitis. Agar dilution methodology was performed to determine the minimal inhibitory concentration of gentamicin, all of which developed resistance toward gentamicin. The findings presented here demonstrated that all these strains harboured toxA depending on PCR-based assay. Nonetheless, RT-PCR technique revealed a wide variation in expression of toxA. Moreover, the cultivation of P. aeruginosa in the presence of gentamicin, significantly (P< 0.05), induced the expression of toxA, in addition to th
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