Higher Minimum Inhibitory Concentration Values Research Articles

Prevalence and factors associated with human colonisation and vancomycin minimum inhibitory concentration of <em>Staphylococcus aureus</em> in Colombo, Sri Lanka

Introduction: Staphylococcus aureus is known to cause a wide variety of diseases of varying severity in humans. The objectives of this study were to determine the prevalence of S. aureus and methicillin resistant S. aureus (MRSA) colonisation, assess factors associated with MRSA colonisation, identify antibiotic susceptibility patterns of MRSA isolates, determine distribution of vancomycin minimum inhibitory concentrations (MIC) of S. aureus and factors associated with high vancomycin MIC values (≥2 µg/ml). Methods: A descriptive cross sectional study was conducted among 341 participants aged 18 to 84 years selected randomly from the Colombo district from 11th December 2018 to 10th April 2019. Samples were collected from the nose, axilla, groin of participants and identification and sensitivity testing of S. aureus were performed based on standard operation procedures given in the Laboratory manual in microbiology published by the Sri Lanka College of Microbiologists (2011). Results: Prevalence of S. aureus and MRSA colonisation in the sample population was 34.6% and 13.78% respectively. All MRSA isolates were susceptible to linezolid. MRSA susceptibility to gentamicin (86%), co-trimoxazole (88 %), and chloramphenicol (80%) was high. Erythromycin had the lowest susceptibility (20%). Inducible clindamycin resistance was demonstrated in 31% of isolates. Meat consumption and consumption of antibiotics within the previous six months showed a significant association with MRSA colonisation. Vancomycin MIC of S. aureus ranged from ≤ 0.5 to 2 µg/ml. Conclusion: As prevalence of MRSA colonisation is 13.78%, more attention should be paid when managing patients with suspected S. aureus infections presenting from the community. Further research on associated factors and environmental triggers are warranted with a larger sample size and different study design to formulate national regulations and guidelines.

An Eco-Friendly Method to Synthesize Potent Antimicrobial Tricyclic Flavonoids.

The rapid emergence and spread of multidrug-resistant microorganisms is threatening our ability to treat common infections, with serious medical, social, and economic consequences. Despite substantial progress in the global fight against antibiotic resistance, the number of effective antibiotics is rapidly decreasing, underlying the urgent need to develop novel antimicrobials. In the present study, the green synthesis of novel iodine-substituted tricyclic flavonoids has been accomplished using an eco-friendly reagent, HPW-SiO2, as a cyclization agent for the precursor 3-dithiocarmamic flavanones. In vitro antimicrobial activity of the new compounds was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentrations. All tested compounds displayed potent inhibitory activity against all tested microbial strains, with the lowest MIC values of 0.12 µg/mL and 0.48 µg/mL recorded for compound 5c against Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. Higher MIC values (7.81 µg/mL) were registered for several flavonoids against Gram-negative bacteria Escherichia coli and Acinetobacter pittii. No inhibitory activity was evidenced against Pseudomonas aeruginosa strain. The highest antifungal activity was displayed by flavonoid 5d against Candida krusei (MIC = 3.9 µg/mL). The same compound also exhibited the most potent bactericidal and fungicidal activity against Bacillus subtilis (0.9 µg/mL) and Staphylococcus aureus (1.97 µg/mL), Candida albicans, and Candida krusei (7.81 µg/mL). Based on the reported results, we believe that the novel iodine-substituted tricyclic flavonoids have good potential to become new antimicrobial agents effective against bacterial and fungal strains, including WHO-priority pathogens.

Expression of Caseicin from Lacticaseibacillus casei and Lacticaseibacillus zeae Provides Insight into Antilisterial Class IIa Bacteriocins.

In this study, an in silico screening approach was employed to mine potential bacteriocin clusters in genome-sequenced isolates of Lacticaseibacillus zeae UD 2202 and Lacticaseibacillus casei UD 1001. Two putative undescribed bacteriocin gene clusters (Cas1 and Cas2) closely related to genes encoding class IIa bacteriocins were identified. No bacteriocin activity was recorded when cell-free supernatants of strains UD 2202 and UD 1001 were tested against Listeria monocytogenes. Genes encoding caseicin A1 (casA1) and caseicin A2 (casA2) were heterologously expressed in Escherichia coli BL21 (DE3) using the nisin leader peptide cloned in-frame to the C-terminal of the green fluorescent gene (mgfp5). Nisin protease (NisP) was used to cleave caseicin A1 (casA1) and caseicin A2 (casA2) from GFP-Nisin leader fusion proteins. Both heterologously expressed peptides (casA1 and casA2) inhibited the growth of L. monocytogenes, suggesting that casA1 and casA2 are either silent in the wild-type strains or are not secreted in an active form. The minimum inhibitory concentration (MIC) of casA1 and casA2, determined using HPLC-purified peptides, ranged from < 0.2µg/mL to 12.5µg/mL when tested against Listeria ivanovii, Listeria monocytogenes, and Listeria innocua, respectively. A higher MIC value (25µg/mL) was recorded for casA1 and casA2 when Enterococcus faecium HKLHS was used as the target. The molecular weight of heterologously expressed casA1 and casA2 is 5.1 and 5.2kDa, respectively, as determined with tricine-SDS-PAGE. Further research is required to determine if genes within Cas1 and Cas2 render immunity to other class IIa bacteriocins.

Biosynthesis of bacteriocin BacZY05-silver nanoconjugates and evaluation of their antibacterial properties.

Bacteriocins are antimicrobial peptides produced by bacteria to prevent the growth of pathogens. Combining bacteriocins with metal nanoparticles, like silver nanoparticles (AgNPs), has developed into a viable strategy to get over bacteriocin limitations. In this study, bacteriocin BacZY05 was extracted from Bacillus subtilis ZY05 and purified using various techniques. The resulting purified bacteriocin was then combined with silver nanoparticles to form bacteriocin silver nanoconjugates (BacZY05-AgNPs). The physicochemical properties of the BacZY05-AgNPs were characterized using various analytical techniques. The mean diameter of the synthesized AgNPs was approximately 20-60nm with an oval or spherical shape. The antimicrobial activity of the BacZY05-AgNPs was evaluated against several indicator strains by their zone of inhibition (ZOI), using the agar well diffusion method. Compared to bacteriocin (ZOI- 13 to 20mm) and AgNPs (ZOI- 10-22mm) alone, the antibacterial activity data demonstrated a 1.3-1.5-fold increase in the activity of bacteriocin-nanoconjugates (ZOI- 22 to 26mm). For Staphylococcus aureus MTCC3103 and Klebsiella pneumoniae MTCC109, BacZY05-capped AgNPs exhibited the lowest minimum inhibitory concentration (MIC), measuring 10.93µg/mL. For Salmonella typhi NCIM2501, the MIC was 28.75µg/mL. The highest MIC value was 57.5µg/mL for Escherichia coli DH5α and Vibrio cholerae MTCC3909. With BacZY05-capped AgNPs, the lowest minimum bactericidal concentration (MBC) of 28.75µg/mL was observed for Staphylococcus aureus MTCC31003. In the cases of Salmonella typhi NCIM2501 and Klebsiella pneumoniae MTCC109 concentration was 57.5µg/mL. Vibrio cholerae MTCC3909 and Escherichia coli DH5α had the highest MBC values at 115µg/mL.

Cannabidiol Demonstrates Remarkable Efficacy in Treating Multidrug-Resistant Enterococcus Faecalis Infections In Vitro and In Vivo

The growing prevalence of multidrug-resistant Enterococcus faecalis infection has become a global concern. There is a demand for alternative antibacterial agents, such as herbal alternatives, such as Cannabidiol, that are cost-effective, non-toxic and efficient. This study investigates the Minimum Inhibitory Concentration (MIC) for planktonic cells and the Minimum Biofilm Eradication Concentration (MBEC) for biofilm formation in multidrug- resistance isolates of E. faecalis isolates, particularly focusing cannabidiol activity. E. faecalis isolates with strong biofilm presence, vancomycin, levofloxacin, and daptomycin displayed high MIC and MBEC values. Cannabidiol exhibited a significantly lower MIC (1 μg/mL) for planktonic cells and a low MBEC (2 μg/mL). Moreover, at low concentrations (2 µg/mL), cannabidiol demonstrated notable reductions in biofilm biovolume, bacterial cell viability and colony-forming unit compared to vancomycin, levofloxacin, and daptomycin. The mice treated with cannabidiol (100 mg/kg) exhibited a significant reduction in E. faecalis bacterial load in internal organs and increased the survival. In conclusion, the findings underscore the promising antibiofilm properties of cannabidiol against E. faecalis, indicating its potential as a novel therapeutic agent.

Genomic analysis of Clostridium perfringens type D isolates from goat farms

C. perfringens type D strains are the leading cause of enterotoxaemia in ruminants such as goats, sheep, and cattle. However, there has been no prior research on the genomic characteristics of C. perfringens type D strains from various regions in China. Here, we investigated the antibiotic resistance, genomic characteristics, and phylogenetic relationship of C. perfringens type D isolates recovered from goat farms in Shaanxi, Gansu, and Ningxia provinces. The antibiotic resistance test indicated that the isolates displayed high minimum inhibitory concentration (MIC) values to sulfafurazole, whereas the other antibiotics tested, such as penicillin, enrofloxacin, and florfenicol, worked well on them. Additionally, only tetracycline resistance genes [tetA(P) and tetB(P)] were identified from the isolates. A collective of 13 toxin genes, including etx and cpe were detected among the isolates. Sequence comparison revealed that the etx and cpe genes shared high sequence identities, and they could coexist on a pCW3-like plasmid, representing a potential risk to both animal breeding and public health. Phylogenetic analysis using core genome multi-locus sequence typing (cgMLST) and core genome single nucleotide polymorphisms (SNPs) revealed the close genetic relationship and potential regional/transregional transmission of the C. perfringens type D isolates in Shaanxi and Gansu provinces. Furthermore, pan-genomic analysis suggested the functional differences at the protein-coding gene level, although isolates from the same source shared a close genetic relationship. In conclusion, this study indicated the antibiotic resistance, virulence markers, potential transregional transmission, and genomic diversity of C. perfringens type D strains from various regions in China, which could provide references for the prevention of C. perfringens foodborne diseases and further research.

Argyreia nervosa-driven biosynthesis of Cu-Ag bimetallic nanoparticles from plant leaves extract unveils enhanced antibacterial properties.

Our study specifically explores the biosynthesis of copper-silver bimetallic nanoparticles (Cu-Ag BMNPs) using Argyreia nervosa (AN) plant leaf green extract as a versatile agent for capping, reducing, and stabilizing. This biosynthesis method is characterized by its simplicity and cost-effectiveness, utilizing silver nitrate (AgNO3) and cupric oxide (CuO) as precursor materials. Our comprehensive characterization of the Cu-Ag BMNPs, employing techniques such as X-ray diffraction (XRD), UV-Vis spectrometry, scanning electron microscopy (SEM), Zetasizer, and Fourier transformed infrared spectrometry (FTIR). FTIR analysis reveals biofunctional groups and chemical bands, while SEM and XRD analyses provide morphological and structural details. To evaluate the antimicrobial properties of the Cu-Ag BMNPs, we conducted disc diffusion and minimum inhibitory concentration (MIC) assays against Escherichia coli (E. coli), with results compared to the standard gentamicin antibiotic. It is observed that the 2% and 5% CuO concentrations of AN Cu-Ag BMNPs exhibit substantial antibacterial activity in comparison to AN extract when tested on EPEC. Among these, the Cu-Ag BMNPs at a 2% concentration demonstrate higher antibacterial activity, potentially attributed to the enhanced dispersion of BMNPs facilitated by the lower CuO doping concentration. These two assays showcased the improved antimicrobial activity of Cu-Ag BMNPs, highlighting their synergistic effect, characterized by high MIC values and a broad zone of inhibition in the disc diffusion tests against E. coli. These results emphasize the significant antibacterial potential of the synthesized BMNPs, with a medicinal plant AN leaf extract playing a pivotal role in enhancing antibacterial activity.

In vitro development of resistance against antipseudomonal agents: comparison of novel β-lactam/β-lactamase inhibitor combinations and other β-lactam agents.

We subjected seven P. aeruginosa isolates to a 10-day serial passaging against five antipseudomonal agents to evaluate resistance levels post-exposure and putative resistance mechanisms in terminal mutants were analyzed by whole-genome sequencing analysis. Meropenem (mean, 38-fold increase), cefepime (14.4-fold), and piperacillin-tazobactam (52.9-fold) terminal mutants displayed high minimum inhibitory concentration (MIC) values compared to those obtained after exposure to ceftolozane-tazobactam (11.4-fold) and ceftazidime-avibactam (5.7-fold). Fewer isolates developed elevated MIC values for other β-lactams and agents belonging to other classes when exposed to meropenem in comparison to other agents. Alterations in nalC and nalD, involved in the upregulation of the efflux pump system MexAB-OprM, were common and observed more frequently in isolates exposed to ceftazidime-avibactam and meropenem. These alterations, along with ones in mexR and amrR, provided resistance to most β-lactams and levofloxacin but not imipenem. The second most common gene altered was mpl, which is involved in the recycling of the cell wall peptidoglycan. These alterations were mainly noted in isolates exposed to ceftolozane-tazobactam and piperacillin-tazobactam but also in one cefepime-exposed isolate. Alterations in other genes known to be involved in β-lactam resistance (ftsI, oprD, phoP, pepA, and cplA) and multiple genes involved in lipopolysaccharide biosynthesis were also present. The data generated here suggest that there is a difference in the mechanisms selected for high-level resistance between newer β-lactam/β-lactamase inhibitor combinations and older agents. Nevertheless, the isolates exposed to all agents displayed elevated MIC values for other β-lactams (except imipenem) and quinolones tested mainly due to alterations in the MexAB-OprM regulators that extrude these agents.

Phytochemical Investigation of Tecoma capensis Flower Aqueous Extract and In Vitro Biological Studies: Anti‐Bacterial and Anti‐Proliferative Activities of its Silver Nanoparticles

AbstractIn this study, we report the synthesis of silver nanoparticles (AgNPs) from Tecoma capensis flower aqueous extract (TcAqFE). The impact of AgNPs on microstructural, optical, antibacterial and antiproliferative properties have been investigated through UV‐visible spectroscopy, X‐ray diffraction, transmission electron microscopy (TEM), fourier infra‐red spectroscopy (FTIR), agar well diffusion technique assay and MTT. The particles size estimated from TEM and XRD is in the range of 1–10 nm. The XRD pattern reveals that the Tecoma capensis silver nanoparticles (TcAgNPs) have a cubic crystal structure. FTIR spectra showed band positions at 1071, 1358, 1620, 1962, 2150, 2920 and 3361 cm−1. Surface plasmon resonance (SPR) in AgNPs became evident with an absorption peak at 407 nm. GC‐MS analysis of ethanolic flower extract revealed the presence of major phytochemical constituents, including Butanal (57.14 %), Propanol (20.23 %), Ethanone (4.88 %), Mesitylene (3.70 %), Hexanal (3.33 %), 4‐Cyclopentene‐1,3‐diol, trans (3.16 %), Furan (2.94 %), 5‐Hepten‐2‐one (2.58 %), and Acetic acid (1.68 %). The antibacterial assay results clearly indicate that the TcAgNPs exhibited the maximum activity against Salmonella typhi, with inhibition zone (IZ) values of (40±1.4 mm), followed by Bacillus subtilis (35.66±2.0 mm), Staphylococcus aureus (32.6±0.64 mm), Escherichia. coli (29.66±2.05 mm), Listeria monocytogenes (27±1.63 mm), and Klebsiella pneumoniae exhibiting the least IZ values (23±1.6 mm). Minimum inhibitory concentration (MIC) values ranged from 0.20 to 2.81 mg/mL. The highest MIC value 2.81 mg/mL was observed in case of Salmonella typhi, while Staphylococcus aureus (0.20 mg/mL), displayed the lowest MIC values. The MIC of Gentamycin also ranged from 0.012 to 0.024 mg/mL. MTT assay demonstrated that the aqueous extract was potent against the cancer cell line A549, with a GI50 of 71.79 μg/mL. These results suggest that TcAgNPs have therapeutic potential and can serve as antibacterial and antiproliferative agents to protect against several ailments.

Prevalence and antimicrobial resistance of Enterococcus spp. isolated from animal feed in Japan.

The rising prevalence of antimicrobial resistance (AMR) of bacteria is a global health problem at the human, animal, and environmental interfaces, which necessitates the "One Health" approach. AMR of bacteria in animal feed are a potential cause of the prevalence in livestock; however, the role remains unclear. To date, there is limited research on AMR of bacteria in animal feed in Japan. In this study, a total of 57 complete feed samples and 275 feed ingredient samples were collected between 2018 and 2020. Enterococcus spp. were present in 82.5% of complete feed (47/57 samples), 76.5% of soybean meal (62/81), 49.6% of fish meal (55/111), 33.3% of poultry meal (22/66), and 47.1% of meat and bone meal (8/17) samples. Of 295 isolates, E. faecium (33.2% of total isolates) was the dominant Enterococcus spp., followed by E. faecalis (14.2%), E. hirae (6.4%), E. durans (2.7%), E. casseliflavus (2.4%), and E. gallinarum (1.0%). Of 134 isolates which were tested for antimicrobial susceptibility, resistance to kanamycin was the highest (26.1%), followed by erythromycin (24.6%), tetracycline (6.0%), lincomycin (2.2%), tylosin (1.5%), gentamicin (0.8%), and ciprofloxacin (0.8%). All Enterococcus spp. exhibited susceptibility to ampicillin, vancomycin, and chloramphenicol. Of 33 erythromycin-resistant isolates, only two showed a high minimum inhibitory concentration value (>128 μg/mL) and possessed ermB. These results revealed that overall resistance to antimicrobials is relatively low; however, animal feed is a source of Enterococcus spp. It is essential to elucidate the causative factors related to the prevalence of AMR in animal feed.

Electronic equipment and appliances in special wards of hospitals as a source of azole-resistant Aspergillus fumigatus: a multi-centre study from Iran

Azole-resistant Aspergillus fumigatus (ARAf), reported as a global public health concern, has been unexpectedly observed in different countries. To identify ARAf and detect azole resistance related to the CYP51A mutation in different hospital environmental samples. In this multi-centre study from Iran, surfaces of electronic equipment and appliances from different hospitals in Iran were sampled using cotton swabs. All samples were cultured using azole-containing agar plates (ACAPs). Recovered Aspergillus isolates were identified at the species level using partial DNA sequencing of the β-tubulin gene. The azole susceptibility testing of A.fumigatus isolates was performed using the Clinical and Laboratory Standards Institute M38-A3 guideline. The sequencing of the CYP51A gene was also performed to detect mutations related to resistance. Out of the 693 collected samples, 89 (12.8%) Aspergillus species were recovered from ACAPs. Aspergillus fumigatus (41.6%) was the most prevalent, followed by A.tubingensis (23.6%) and A.niger (15.6%). Among 37 isolates of A.fumigatus, 19 (51.3%) showed high minimum inhibitory concentration (MIC) values to at least one of the three azoles, voriconazole, itraconazole, and posaconazole. CYP51A polymorphisms were detected in all 19 isolates, of which 52.6% showed the TR34/L98H mutation. Other detected mutations were G432C, G448S, G54E/G138C, F46Y, and Y121F/M220I/D255E. T289F and G432C were the first reported mutations in ARAf. There was a considerable level of azole resistance in hospital environmental samples, a serious warning for patients vulnerable to aspergillosis. Our findings have also revealed a different mutation pattern in the CYP51A gene.

The effect of carbonyl cyanide m-chlorophenyl-hydrazine on antibiotic susceptibility in MDR Enterobacteriaceae isolates in Babylon, Iraq

Abstract Background: One of the efflux pump inhibitors is carbonyl cyanide 3-chlorophenylhydrazone (CCCP) that has often been found to increase the susceptibility of a number of multi-drug resistant (MDR) MDR bacteria, isolated from human clinical specimens. Objectives: To investigate the role of active efflux system to aminoglycoside and quinolones resistance in clinical isolates of Enterobacteriaceae using the efflux pump inhibitor CCCP. Materials and Methods: Enterobacteriaceae isolates were recovered from different clinical samples from hospitalized patients. The minimum inhibitory concentrations (MICs) of antibiotics (levofloxacin, ciprofloxacin, and gentamycin) were compared with and without the efflux pump inhibitor (CCCP) in order to confirm the effective role of the efflux pump in our isolates. Results: The results found that out of 280 clinical samples, only 134 (47.1%) isolates belonged to Enterobacteriaceae. Polymerase chain reaction (PCR) results showed that six (42.8%) out of 14 selected MDR isolates were positive for efflux pump gene oqxA. However, no isolates showed positive results for the efflux pump oqxB. The results of MIC for 14 Enterobacteriaceae isolates against these three antibiotics showed that all isolates had MIC ≥128 μg/mL in the absence of CCCP for levofloxacin, ciprofloxacin, and gentamycin. The results showed the MIC of levofloxacin and ciprofloxacin were reduced for isolates, and the growth of bacteria was inhibited in presence of the CCCP. However, all Enterobacteriaceae isolates showed high MIC values (≥128) even in the presence of the CCCP which indicates no effect the inhibitor in reducing the MIC of the isolates for Gentamycin. Conclusion: From this study, we can conclude that high prevalence of efflux pumps gene (oxqA) was detected among MDR and XDR Enterobacteriaceae isolates and the efflux pump inhibitor (CCCP) has a positive effect and improves the sensitivity of MDR isolates to ciprofloxacin, levofloxacin but not gentamicin.

In Vitro Activity and Atom Pair Fingerprint Analysis of Potent Hits from Malaria Box against Staphylococcus aureus Isolated from Cows with Clinical Mastitis

Staphylococcus aureus (S. aureus) is one of the most prevalent contagious bacterial pathogens causing clinical bovine mastitis. In the present study, plate (A), which consists of 80 compounds (40 drug-like and 40 probe-like), was assessed from the Malaria Box against the in vitro growth of S. aureus isolated from cows naturally infected with S. aureus. Anti-Staphylococcus aureus medications that are newer and more potent than those that have been used previously were discovered. Bioinformatics analysis for the potent identified hits was performed. Three compounds—two probe-like and one drug-like—showed strong inhibitory action against S. aureus growth in vitro. Among these hits, MMV665941 exhibited the highest minimum inhibitory concentration value of 0.0078. Combination therapy was carried out using the most potent anti-S. aureus medication, MMV665941, and the traditionally used anti-S. aureus drug, amoxicillin/clavulanate (Augmentin 625®). The atom pair fingerprint (APfp) analysis revealed that MMV665941 and Augmentin showed maximum structural similarity. Based on the results obtained, it can be concluded that the Medicines for Malaria Venture Box has a wealth of potential anti-S. aureus candidates.

Investigating In Vitro Antioxidant and Antimicrobial Activity of Different Sorbus Species in Artvin Province of Türkiye

In the present study, three Sorbus species in the Rosaceae family naturally growing in Artvin province of Turkey were collected. To determine the antioxidant activity, total phenolic and flavonoids capacity of the extracts, their scavenging capacity for (2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, reducing capacity for Fe3+ (FRAP) and copper (II) ions (CUPRAC) were analyzed. Besides, disc diffusion method was used to determine antibacterial activity. It was found that all Sorbus fruit, flower, leaf and pedicle methanolic extracts showed different levels of antioxidant activity. Results of the the total polyphenol, total flavonoid, FRAP, CUPRAC and DPPH analysis, the highest activity was measured in S. persica pedicle, S. umbellate var. cretica leaf, S. persica leaf, S. umbellata var. cretica leaf and S. persica leaf extracts as 25.7 ± 16.49 mg GAE/g, 7.469 ± 0.4926 mg of quercetin/g, 6.248 ± 0.2374 μmol FeSO4.7H2O/g and, 164.4 ± 4.209 mmol TEAC and 46.33 μg/mL, respectively. It was revealed that methanolic extracts of Sorbus plant showing antibacterial activity had very high minimum inhibitory concentration (MIC) values compared to ampicillin. Thus, considering the findings of the present study, it could be stated that these species merit further studies as natural antioxidant and antibacterial sources.

Prevalence of carbapenemases among Gram-negative bacteria in Tunisia: first report of KPC-2 producing Acinetobacter baumannii.

The rapid evolution of the antibacterial resistance problem worldwide, including the Mediterranean countries, constitutes a real threat to public health. This study aims to characterize carbapenemase encoding genes among Gram-negative bacteria collected from some Tunisian hospitals. Twenty-two clinical carbapenem-resistant Gram-negative bacteria were recovered, and identified by the matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) method. Antibiotic resistance was tested by disk diffusion method on Muller-Hinton Agar. The minimum inhibitory concentration (MIC) for imipenem was revealed by the E-test method. Carbapenemase encoding genes were screened by polymerase chain reaction (PCR). Genetic relatedness was performed by the pulsed field gel electrophoresis (PFGE) method. Our isolates, identified as K. pneumoniae (n = 7), P. mirabilis (n = 1), A. baumannii (n = 13), and P. aeruginosa (n = 1), presented high MIC values for imipenem. Enterobacerales were resistant to carbapenems due to OXA-48 production. Only, four K. pneumoniae harbored the blaNDM-1 gene. VIM-2 production was detected in P. aeruginosa. However, OXA-23 production was observed in A. baumannii isolates, one of which co-produced the KPC-2 enzyme that was identified for the first time in Tunisia in this species. A high genetic diversity was demonstrated by pulsed-field gel electrophoresis in K. pneumoniae and A. baumannii after XbaI and ApaI digestion respectively. Our findings highlight the spread of various unrelated clones of carbapenemase-producers in some Tunisian hospitals as well as the spread of several carbapenemase types.

Investigation of the antimicrobial susceptibility patterns of marine cyanobacteria in Bohai Bay: Cyanobacteria may be important hosts of antibiotic resistance genes in marine environment

Marine cyanobacteria, as widely distributed and photosynthetically autotrophic bacteria in the ocean, may contribute to the global dissemination of antibiotic resistance genes (ARGs) and develop a different antimicrobial susceptibility pattern from heterotrophic bacteria and cyanobacteria from freshwater environments. However, studies on antimicrobial susceptibility and the carriage of ARGs in marine cyanobacteria are still very limited. In this study, the antibiotic resistance characteristics of cyanobacteria in nearshore waters were examined through field monitoring and laboratory investigations, which included PCR detection and ARG transformation. The results showed a positive correlation between marine cyanobacteria and some ARGs in the nearshore waters of Bohai Bay. Moreover, most screened cyanobacteria showed high minimum inhibitory concentration (MIC) values for polymyxins, tetracyclines, kanamycin, and sulfonamides, moderate MIC values for streptomycin, chloramphenicol, rifampicin, and norfloxacin, and low MIC values for roxithromycin and cephalosporins. The blaTEM, blaKPC, sul1, sul2, strA, tetA, tetB, tetC, tetM, mdfA, and intI1 genes were detected in the screened marine cyanobacteria. The highest detection rates were observed for blaTEM (93.3 %), sul1 (56.6 %), sul2 (90 %), and strA (73.3 %). The detection rate of tetA (33.3 %) was the highest among the tetracycline resistance genes, and mdfA, a multidrug-resistant pump gene with resistance to tetracycline, also showed a high detection level (23.3 %). Overall, most of the screened marine cyanobacteria were found to tolerate multiple antibiotics in seawater, and the condition of the ARGs carriage was serious. Furthermore, the screened marine Synechocystis sp. C12-2 demonstrated the ability to accept ARGs on the RP4 plasmid through natural transformation and showed reduced sensitivity to ampicillin, suggesting the possibility that some marine cyanobacteria could acquire ARGs from the environment through horizontal gene transfer. Thus, marine cyanobacteria may play an important role in the propagation of marine ARGs.

OPTIMIZATION OF EXPRESSION AND EVALUATION OF RECOMBINANT ENTEROCIN-P, AS FOOD BIO PRESERVATIVE ON SOME FOOD SPOILAGE BACTERIA

This study optimized the expression of the enterocin P peptide (EntP) in CHO cells using medium additions. Furthermore, the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and anti-biofilm effects of Ent-P were examined against several gram positive and gram-negative microorganisms. The findings indicated that increasing medium with 0.75 percent glycerol and 0.75 percent DMSO boosted Ent-P peptide synthesis by around two times. According to Ent-P antimicrobial evaluations, Shigella disentri (4 g/mL) and Escherichia coli (128 g/mL) had the lowest and highest MIC values, respectively. In comparison to Enterococcus faecalis and Escherichia coli (3+ to 2+), the Ent-P peptide shown a strong ability to suppress the formation of the biofilm generated by Staphylococcus aureus and Pseudomonas aeruginosa (4 + to +1).

Phenotypic and genotypic diversity of yeast isolated from cancer patients and their environment and their antifungal sensitivity pattern

Abstract. Al-Darraji ZDG, Mohammed-Ameen MKM. 2023. Phenotypic and genotypic diversity of yeast isolated from cancer patients and their environment and their antifungal sensitivity pattern. Biodiversitas 24: 4166-4174. This study aimed to investigate yeast diversity and their antifungal susceptibility patterns in 853 samples collected from cancer patients, their apparently healthy companions, their beds, their tables, and indoor hospital air. The samples were cultured and identified using classical phenotypic characteristics and a molecular method utilizing amplification of ITS conservative regions of rRNA. The sum of phenotyping and genotyping identification revealed that 102 yeast isolates included 6 genera and 14 species. Candida sp. was the most dominant genera (84.31%), followed by Naganishia sp. (10.78%). Candida albicans (24.50%) and C. krusei (16.66%) were the most prevalent yeast species. Fluconazole, caspofungin, and voriconazole exhibited potent antifungal activities against the most yeast species with low minimum inhibitory concentration (MIC) values compared with high MIC (64 µg/mL) values against Meyerozyma guilliermondi, Naganishia difflunes, and C. tropicalis. To conclude, the antifungal activity was isolate- and species-specific and the higher antifungal concentrations led to a more-rapid expression of activity. The high isolation rate of yeasts from beds and tables, advocated the use of various monitoring systems to ensure thorough cleaning and consistent disinfection of surfaces around patients and health care providers. The study findings showed that the molecular method was superior to the phenotyping technique in identifying yeast isolates. While similar research has been performed in different locations, the current project represents a unique milestone for this particular institution, and offers an opportunity to advance research in this area.

Evaluation of Antibacterial and Antioxidant potential of Melia. Azedarach linn. and Psidium guajava linn. Leaf extracts

The present study is intended to evaluate and analyze in-vitro antibacterial and antioxidative activities of leaf extracts of Melia azedarach Linn (M. azedarach L.) and Psidium guajava Linn (P. guajava L.). In-vitro antibacterial activity was measured using agar well diffusion assay against Pseudomonas aeruginosa and Staphylococcus aureus strains. In-vitro antioxidant activity was estimated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. Among both plants high minimum inhibitory concentration values are observed with P. guajava L. ethanol extract at 47.6µg/ml for S. aureus and 43.7µg/ml for P. aeruginosa, respectively. The results revealed that 20µg/ml ethanol extracts of P. guajava L. exhibited the highest radical % scavenging activity (76.24%) succeeded by methanol extracts (72.78%), respectively indicating they are effective solvents to extract phenolic compounds. We demonstrated that for both bacterial strains, ethanol followed by methanol extracts showed significant antibacterial activity in P. guajava L.in dose dependent manner indicating the presence of high flavonoids, tannins, and steroids. Our results revealed that both plants are vital reservoirs of phytochemicals with both antibacterial and antioxidant capacities.

Clinical, Microbiological, and Molecular Characterization of Candia (Starmera) stellimalicola, a Rare Fungal Pathogen Causing Human Infections.

Candia (Starmera) stellimalicola is a yeast species spread worldwide and recovered from varieties of ecological reservoirs, but human infections are rarely reported. In this study, we reported an intra-abdominal infection case caused by C. stellimalicola and described its microbiological and molecular characteristics. C. stellimalicola strains were isolated from ascites fluid of an 82-year-old male patient having diffuse peritonitis with fever and elevated WBC counts. Routine biochemical and MALDI-TOF MS methods failed to identify the pathogenic strains. Phylogenetic analysis of 18S, 26S and internal transcribed space (ITS) rDNA regions, as well as whole-genome sequence identified the strains as C. stellimalicola. Compared with other Starmera species, C. stellimalicola had unique physiological characteristics including thermal tolerance (able to grow at 42°C), which may prompt its environmental adaptability and potential for opportunistic human infection. Fluconazole minimum inhibitory concentration (MIC) values of the strains identified in this case was 2mg/L, and the patient had a favorable outcome after receiving fluconazole treatment. In comparison, the majority of C. stellimalicola strains previously documented had high MIC values (≥ 16mg/L) to fluconazole. In conclusion, with the raise in human infections caused by rare fungal pathogens, molecular diagnostic remains the most efficient way for accurate species identification; and antifungal susceptibility testing is essential to guide proper patient management.