Research Article
Antibiotic Resistance and Biochemical Characteristics Co- Existence among Staphylococcus aureus Exposed to Disinfectants, Photosensitizer and Laser Irradiation
Mohemid Maddallah Al-Jebouri, Hussein Saher Al-Obaidy
Middle East Research Journal Microbiology and Biotechnology; 228-244.
https://doi.org/10.36348/merjmb.2026.v06i04.002
Background: Laser biostimulation is potentially a useful tool in the treatment of wounds, particularly those cutaneous and subcutaneous wounds that are either complicated by infection by resistant bacteria or inherently require a prolonged period of time to heal. These resistance variants which multiply in hospital environment could lead to serious epidemic outbreaks. Also, the consequence changes in phage susceptibility patterns might be affect the epidemiological reporting. Methodology: The present work was conducted on 200 patients with wounds. Their ages ranged from 1-40 years. Wound swab was taken on the third postoperative day from hospitalized patients and on the seventh postoperative day from patients attended outpatient clinic. The isolated Staphylococcus aureus isolates were subjected to susceptibility diffusion discs of penicillin, benzathine penicillin, chloramphenicol, streptomycin, gentamicin, tetracycline, erythromycin, colistin, nitrofurantoin, Fucidin and clindamycin. All strains were exposed to series of disinfectants exposure was as follow: hibitane, Dettol, cetavlon, savlon and providine-iodine. Biostimulation was carried out utilizing the laser light of Helium-Neon (He/Ne) gas type. Results: The biochemical characters were changed after disinfectants exposure and the negativity increased to urease, arginine decarboxylase and mannitol fermentation. Laser light exposure lead to an increase in negativity to certain biochemical characters like urease and Voges-Proskauer. The resistance frequency to antibiotics was decreased e.g. resistance number to chloramphenicol, benzathine penicillin and gentamicin was, and the 8, 8 and 3 respectively before exposure and then became 7, 6 and 2 respectively after laser light exposure. Conclusions: three strains were resistant to gentamicin before exposure and the number was increased to ten after second exposure to various disinfectants. Susceptibility of the ten strains to nitrofurantoin did not change after exposure. Laser light exposure led to an increase in negativity to certain biochemical characters like urease and Voges-Proskauer. The resistance of S. aureus frequency to antibiotics was decreased. The combination of laser with providine-iodine resulted in a marked reduction in both the frequency of resistant strains and the number of resistance determinants, indicating a strong synergistic antimicrobial effect.
Research Article
R-Plasmid Transfer Frequencies from Faecal Isolates of Escherichia coli of Cancer and Noncancer Patients to Escherichia coli K12 Strain
Mohemid Maddallah Al-Jebouri, Ibraheem Abdul-kareem Al-Ani
Middle East Research Journal Microbiology and Biotechnology; 245-256.
https://doi.org/10.36348/merjmb.2026.v06i04.003
Abstract: Background: Diarrheagenic E. coli is currently categorized into a limited number of groups, primarily based on the presence of specific virulence genes, and is classified under a single pathogenic variant (pathovar). The significance of Horizontal Gene Transfer (HGT) in the evolution of the genome and pathogenicity of STEC is far more comprehensive than we previously realized. Materials and Methods: 400 patients were included and they were 200 patients with cancer diseases and 200 patients complaining of other illnesses. Specimens were taken from faeces and cultured on MacConkey agar. Isolated bacteria were identified using APIE System. Antibiotic sensitivity testing and resistance transfer from local E.coli to E.coli K12 was carried out as described elsewhere. Results: The rate of transfer of resistance traits from pathogenic E.coli to E.coli K12 was ranged between 10-6 to 10-3. The frequency of resistance transfer of carbenicillin, ampicillin and sulfonamide was 80.5, 72.1 and 62.5% respectively. The comparative analysis of antibiotic resistance patterns before and after R-factor transfer demonstrated substantial horizontal dissemination of multidrug resistance among pathogenic Escherichia coli isolates. The mean resistance-retention efficiency after conjugative transfer was 59.4%, confirming that a large proportion of resistance determinants were plasmid mediated and transmissible to recipient E. coli K12 strains. Conclusions: The rate of transfer of resistance traits from pathogenic E.coli to E.coli K12 was ranged between 10-6 to 10-3. The log–linear regression analysis demonstrated a statistically significant positive relationship between donor and recipient resistance-gene transfer frequencies among pathogenic Escherichia coli serotypes and E. coli K12 recipients (p = 0.0006). The frequency of resistance transfer of carbenicillin, ampicillin and sulfonamide was 80.5, 72.1 and 62.5% respectively. This rate of transfer was almost high than media transfer rate. There was a lower rate of transfer for nalidixic acid, colistin and nitrofurantoin and the rate was 20, 3.3 and 0% respectively. The statistical analysis demonstrated a significant positive association between the number of antibiotic-resistant Escherichia coli isolates and the frequency of resistance transfer to recipient E. coli K12 strains (Spearman r = 0.788, p = 0.0014). Overall, the findings provide strong evidence that R-factor-mediated conjugation plays a major role in the dissemination of antimicrobial resistance among pathogenic Escherichia coli populations (Figure 3). The most suitable mathematical descriptor considered was resistance-retention efficiency modeling: Retention Efficiency (%) =Before Transfer/After Transfer×100.
Research Article
Metagenomic Analysis of Antimicrobial Resistance in Wastewater and Its Environmental Impact
Dania Ali Azeiz Al-Saadi
Middle East Research Journal Microbiology and Biotechnology; 257-265.
https://doi.org/10.36348/merjmb.2026.v06i04.004
Antimicrobial resistance (AMR) in wastewater is one of the most significant One Health threats, and wastewater treatment plants (WWTPs) are important hybrid reservoirs and dissemination routes for antibiotic resistance genes (ARGs) exploiting environmental resources. Shotgun metagenomics was used in this study to profile the resistome, mobile genetic elements (MGEs) and microbial hosts from influent and effluent samples across municipal and hospital-associated WWTPs. We identified hundreds of unique ARGs in each system, with multidrug, tetracycline, macrolide, aminoglycoside and β-lactam resistance determinants predominating and included clinically relevant genes i.e. blaCTX-M-15 sul1 tet(Q), qnr variants. While conventional treatment decreased total ARG loads, some ARGs abundant in raw influents became enriched in effluents and many resistance determinants persisted after treatment. Genome-resolved revealed that ARGs were primarily associated with Pseudomonadota and Bacillota, many plasmids contained more than one ARG, indicating multi-horizontal gene transfer events across IncF, IncQ, IncL/M and Col-type plasmids. The environmentally risk assessment shows that WWTP effluents are major contributors to surface-water resistomes, downstream riverine compartments harbour high-risk ARGs in pathogenic taxa, and biosolids drive soil contamination. These findings highlight the urgent need for improved treatment barriers, such as advanced oxidation processes, as well as widespread genomic surveillance to reduce the risk of AMR dissemination from wastewater into ecosystems.
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