biofilms

Acinetobacter baumannii is a prevalent pathogenic bacterium that causes nosocomial infections globally. A multitude of A. baumannii strains have acquired a broad spectrum of antibiotic resistance in recent years, primarily due to the influence of genes associated with the production of biofilms.

Two hundred clinical isolates were acquired and described from Shahid Mostafa Khomeini, Tohid, and Shahid Motahari hospitals in Tehran, Iran, in 2018. The disk diffusion method was then used to determine whether genes related to the formation of outer membrane protein A (ompA), exopolysaccharide (epsA), and biofilm-associated protein (Bap) by polymerase chain reaction were present or not, as per the 2020 Clinical and Laboratory Standards Institute (CLSI) guidelines.

We found 60 different types of A. baumannii, all confirmed by blaOXA-51-like gene area sequencing and polymerase chain reaction (PCR) 16S rRNA. It was found that A. baumannii isolates were completely unaffected by piperacillin, meropenem, cefotaxime, ceftazidime, ceftriaxone, and ciprofloxacin. We also found that 96.6% of the A. baumannii isolates had genes related to making ompA biofilms, 85% had genes related to making epsA biofilms, and 75% had genes related to making Bap biofilms.

After examining the elevated level of antibiotic resistance among A. baumannii isolates and the existence of biofilmassociated genes in clinical isolate, this study showed that virulence genes linked to the formation of epsA, Bap, and ompA biofilms are a major cause of antibiotic resistance.

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) has become a major global concern. Quorum sensing (QS) regulates the expression of biofilm formation genes and virulence factors. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) is widely used in epidemiological molecular studies.

The purpose of the present study was to determine the QS characteristics and genetic relatedness of CRPA.

A total of 57 non-duplicative CRPA isolates were collected. A microtiter plate assay was used to assess biofilm formation. After DNA extraction, PCR was performed to detect resistance elements and QS-encoded genes. Enterobacterial repetitive intergenic ERIC-PCR was conducted using specific primers.

The biofilm formation assay revealed that 10.5%, 19.3%, and 70.2% of isolates formed weak, moderate, and strong biofilms, respectively. Of the isolates, 75.4%, 64.9%, 12.3%, and 8.7% carried the bla IMP , bla VIM , bla NDM , and bla KPC genes, respectively. Additionally, 73.7%, 7.0%, and 1.7% of CRPA isolates carried the bla OXA-48-like , bla OXA-23-like , and bla OXA-20/40-like genes, respectively. The prevalence of the lasR , lasI , rhlI , rhlR , aprR , aprA , and rhlAB genes were 100%, 96.5%, 92.9%, 89.5%, 84.2%, 73.6%, and 63.2%, respectively. Enterobacterial repetitive intergenic ERIC-PCR revealed eight distinct clusters (A, B, C, D, E, F, G, and H) using a similarity cut-off of ≥ 60%.

The findings indicate a high prevalence of strong biofilm formation and quorum-sensing genes among CRPA isolates. The study highlights the importance of biofilm production and genetic diversity in CRPA isolates, underscoring the challenges in infection control and treatment strategies.

Candida species are a leading cause of fungal infections worldwide. Candidiasis, the disease caused by Candida , represents a significant public health concern globally. Candida albicans is the most common causative agent, responsible for 50 - 90% of invasive candidiasis cases. Candida albicans employs various virulence factors to adhere to, invade host tissues, and cause disease.

This study aimed to detect and compare the virulence factors of C. albicans , including hydrophobicity, biofilm formation, ergosterol content, and secretory enzymes, in clinical and environmental samples.

A total of 105 clinical and 165 environmental samples suspected of containing C. albicans were collected from Imam Khomeini Hospital in Ahvaz, Iran. The isolates were evaluated for five potential virulence factors: Ergosterol content, cell surface hydrophobicity (CSH), biofilm formation, protease activity, and phospholipase activity.

Sixty C. albicans isolates were identified, consisting of 30 clinical and 30 environmental isolates. Biofilm production was observed in 100% of clinical isolates and 80% of environmental isolates (P < 0.001). Protease activity was detected in 66.6% of clinical isolates and 76.7% of environmental isolates (P = 0.008). Phospholipase activity was present in 60% of clinical isolates and 76.7% of environmental isolates (P = 0.262). Clinical isolates exhibited higher CSH (66.4 ± 9.8) compared to environmental isolates (47.7 ± 17.0) (P < 0.001). The ergosterol content was 1.2 ± 0.5 in clinical isolates and 1.1 ± 0.3 in environmental isolates.

Biofilm formation was a consistent characteristic of clinical isolates, while phospholipase and protease activity were more prevalent in environmental C. albicans isolates. The results suggest possible cross-contamination between patients and the environment, as the virulence factors of clinical and environmental isolates were similar.

This study aimed to investigate the biofilm formation ability of K. pneumoniae clinical isolates using phenotypic and genotypic methods. Additionally, the association of biofilm formation with antibiotic resistance and the presence of biofilm-related genes was investigated.

In this research, a total of 52 clinical isolates of K. pneumoniae were collected from educational hospitals affiliated with Babol University of Medical Sciences from March to October 2023. K. pneumoniae isolates were identified through standard microbiological and biochemical tests. Disk diffusion, microtiter plate, and polymerase chain reaction assays were also performed to evaluate the biofilm formation ability of these isolates.

K. pneumoniae isolates were obtained from various clinical specimens. The isolates showed the highest resistance to ceftazidime (54%) and the lowest resistance to amikacin (17%). More than 48% of the isolates were multidrug resistant. Of the 52 K. pneumoniae isolates, 43 (82.69%) isolates produced biofilm, whereas the remaining nine (17.3%) did not. K. pneumoniae isolates harbored biofilm formation genes, including treC (78.84%), wcaG (71.15%), mrkD (65.38%), mrkA (63.46%), iutA (40.38%), and magA (15.38%).

This study demonstrates that K. pneumoniae isolates are highly pathogenic because of antibiotic resistance and carrying biofilm genes. Given the biofilm formation propensity of these strains, it is imperative to elucidate the underlying mechanisms of biofilm formation in K. pneumoniae. Developing strategies to inhibit this process is paramount in the effective management of infections caused by this pathogen.

The biofilm formation has been widely recognized as one of the main mechanisms of antimicrobial resistance development in microorganisms. However, few studies are focusing on this phenomenon in Candida spp. in clinical settings, especially on immuno-compromised patients.

In this study, both the rate of biofilm formation in those patients and its drug susceptibility in initial and mature biofilm were assessed using crystal violet assay and dilution method.

The results demonstrated that the biofilm formation rate was similar between albicans and non-albicans Candida. However, the biofilm formation capacity was more pronounced in non-albicans Candida, especially, C. glabrata. As expected, there was a significant relationship between biofilm formation and drug resistance. In addition, our study reconfirmed that the age of high concentration of antifungal agents only affected Candida before its biofilm formation regardless of its biofilm formation capacity. In the contrary, once the biofilm was formed even elevated drug concentrations did not show sufficient efficacy, highlighting a need for high dosage at the early stage of treatment for those patients.

The results of this study highlighted the importance of using appropriate antifungal agents for Candida treatment before the formation of biofilm.

Over the past decades, the role of biofilm-forming Staphylococcus aureus strains in urinary tract infections (UTIs) has garnered significant attention.

This study aimed to determine the epidemiological characteristics and diversity of S. aureus strains isolated from patients with UTIs in Isfahan, Iran, in 2017, with regard to their antimicrobial resistance, biofilm formation, and phylogenetic profiles. Additionally, the study investigated potential relationships among these factors statistically to develop efficient control and treatment approaches.

All patients with symptomatic UTIs who had positive urine cultures for S. aureus during the study period at the laboratory of a referral hospital in Isfahan were included. All isolates were identified using specific primers for the nuc A gene. Their biofilm formation capacity was evaluated using a combination of the microtiter plate and Congo-red agar methods. Antibiotic susceptibility testing was performed using the disk diffusion method. The presence of genes involved in biofilm formation and resistance to cefoxitin, aminoglycosides, and fluoroquinolones was detected using polymerase chain reaction (PCR). Staphylococcal cassette chromosome mec (SCC mec ) typing, agr typing, and phene plate (PhP) typing were employed to investigate the diversity of collected strains.

Results showed that 19%, 57%, and 24% of confirmed S. aureus strains were strong, intermediate, and non-biofilm formers, respectively. The highest rate of resistance was against nalidixic acid (77%), followed by streptomycin (73%). The ica D and ica A genes had the highest frequency among biofilm-producing strains. gyr A (44%) and grl A (35%) were the most frequent genes among fluoroquinolone-resistant strains, while aph (3′)-IIIa was the most prevalent aminoglycoside-modifying enzyme gene. The majority of bacterial strains harbored SCC mec type III and agr type I. PhP typing of strains revealed the presence of 8 common types (CTs) and 14 single types (STs), with CT2 being the dominant type.

The present investigation revealed various biofilm production capacities, antimicrobial resistance profiles, and clonal lineages in S. aureus isolated from patients with UTIs. These findings provide further insights into the epidemiology and pathogenicity of S. aureus strains in Iran, thereby improving the quality of surveillance and therapeutic protocols.

One of the burning issues facing healthcare organizations is multidrug-resistant (MDR) bacteria. P. aeruginosa is an MDR opportunistic bacterium responsible for nosocomial and fatal infections in immunosuppressed individuals. According to previous studies, efflux pump activity and biofilm formation are the most common resistance mechanisms in P. aeruginosa. The aim of this study was to propose new antimicrobial peptides (AMPs) that target P. aeruginosa and can effectively address these resistance mechanisms through in silico and in vitro assessments. Since AMPs are an attractive alternative to antibiotics, in vitro experiments were carried out along with bioinformatics analyses on 19 Nef peptides (derived from the HIV-1 Nef protein) in the current study. Several servers, including Dbaasps, Antibp2, CLASSAMP2, ToxinPred, dPABBs and ProtParam were used to predict Nef peptides as AMPs. To evaluate the binding affinities, a molecular docking analysis was performed with the HADDOCK web server for all Nef peptide models against two effective proteins of P. aeruginosa (MexB and PqsR) that play a role in efflux and quorum sensing. Moreover, the antibacterial and antibiofilm activity of the Nef peptides was investigated in a resistant strain of P. aeruginosa. The results of molecular docking revealed that all Nef peptides have a significant binding affinity to the abovementioned proteins. Nef-Peptide-19 has the highest affinity to the active sites of MexB and PqsR with the HADDOCK scores of -136.1 ± 1.7 and -129.4 ± 2, respectively. According to the results of in vitro evaluation, Nef peptide 19 showed remarked activity against P. aeruginosa with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 10 µM and 20 µM, respectively. In addition, biofilm inhibitory activity was observed at a concentration of 20 µM. Finally, Nef peptide 19 is proposed as a new AMP against P. aeruginosa.

The lack of understanding of how pollutant removal occurs in biofilter reactors and bacterial community dynamics makes this worthy of study. This review explores biofiltration processes, commonly used biofilter types, bacterial community dynamics, and pollutant removal mechanisms in biofilters.

This review used data from previous studies published on Scopus, EBSCO, and ProQuest, categorized into parameters such as the biofiltration process, types of biofilters, bacterial community dynamics, and pollutant removal mechanisms. The data were narrated, analyzed in a table, and presented in a review.

In the biofilter reactor, microorganisms cover the medium, allowing pollutants to flow through gaps and contact the biofilm layer. As the biofilm thickens, adhesion weakens, leading to new colonies. Submerged-bed biofilters, trickling filters, and packed column aeration and gasification systems effectively remove nutrients from aquatic environments. Biofilter bacterial communities are categorized by filter layer depth, with fast-growing, less specialized communities in the upper layer and more specialized communities in the bottom layer. Pollutant biodegradation depends on various factors such as nutrient availability, oxygen concentration, pH, bioavailability of contaminants, and physical and chemical characteristics of the biomass.

A biofilter reactor uses microorganisms to cover a medium, allowing pollutants to flow through gaps and contact a biofilm layer that degrades organic compounds. Submerged-bed biofilters, trickling filters, and packed column aeration systems can effectively remove pollutants. Biofilter bacterial communities are categorized by filter layer depth, with fast-growing, less specialized communities in the upper layer, and more specialized communities in the bottom layer.

The emergence of the multidrug-resistant bacteria strain has become a global world crisis. This study was designed to evaluate the antibiofilm and synergistic effects of Lippia multiflora (L. multiflora) leaf extracts on the activity of cefotaxime against the methicillin-resistant Staphylococcus aureus (S. aureus).

The synergistic effect of methanol and dichloromethane extracts on the bactericidal activity of cefotaxime was determined by using the antibiotic susceptibility test on agar medium. The antibiofilm activity of the extracts was measured by using the crystal violet method. The antioxidant potential of the extracts was assessed by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Ferric Reduction Activity Potential (FRAP) methods. The main secondary metabolites groups were analyzed by using different standard analytical tests. The total phenolics and total flavonoids were quantified spectrophotometrically.

The methanol extract (final concentration of 100 µg/ml) inhibited the formation of bacterial biofilm more than salicylic acid (p<0.05). All extracts combined with cefotaxime (20 µg and 200 µg) showed good synergistic bactericidal effect on S. aureus with inhibitory diameters of up to 40 mm. The methanol extract showed higher total phenolics (462.20±10.90 mg EAG/g) and total flavonoids (26.20±0.20 mg EQ/g) contents than the dichloromethane extract (96.70±1.70 mg EAG/g and 8.00±1.20 mg EQ/g). Moreover, the methanol extract showed a higher FRAP reducing power (353.6± 4.17 mmol EQ/g) than the dichloromethane extract (385.3±7.01 mmol EQ/g). Qualitative phytochemical analysis showed the presence of tannins, flavonoids, terpenes and sterols in both extracts.

These data showed that L. multiflora leaves contain effective antibacterial phytomolecules for combating bacterial resistance.

Staphylococcus aureus is one of the most common agents of nosocomial infection worldwide. Methicillin-resistant and biofilm-associated infections of this bacterium have become a clinical concern in patients. This research aimed to identify biofilm-forming ability and accessory gene regulator (Agr) - specific group of clinical isolates of methicillin-resistant S. aureus (MRSA) in Northern Iran.

In 2021, a total of 200 clinical isolates were identified as S. aureus by biochemical tests. The disk diffusion method was used to examine the antibiotic resistance of isolates and the microplate method was applied to investigate the biofilm production capability. In addition, the PCR method was used to determine the frequency of biofilm-associated genes and Agr typing of MRSA isolates. P £ 0.05 was considered significant.

Overall, 62.5% of isolates were methicillin-resistant and 75% were multiple antibiotic-resistant. Biofilm-forming ability was detected in 99 (79.2%) methicillin-resistant isolates in which icaA and icaD were found in 85% and 78% of biofilm-producing isolates, respectively. Type 1 of the Agr gene was the most common type among methicillin-resistant isolates. The frequency of biofilm-associated genes showed a significant association with MDR phenotype and the presence of Agr locus (P £ 0.05).

The present findings indicate a high frequency of biofilm and antibacterial resistance in methicillin-resistant S. aureus isolates in Guilan Province. These findings suggest reliable and rapid identification of biofilm-forming MRSA strains to prevent the spread of these bacteria.

Biofilm related implant infection is undoubtedly a relevant challenge in total knee arthroplasty (TKA) with our comprehension steadily progressing and novel management approaches being developed. The aim of this article was to review the most important advances in approaches to combat infections due to biofilm-forming bacteria in TKA. The main conclusions were the following: 1) Fundamental management techniques for infected TKA include open DAIR (debridement, antibiotics, and implant retention), and one and two-stage revision TKA; 2) Continuous local antibiotic perfusion (CLAP) appears to diminish the risk of periprosthetic joint infection (PJI); 3) Restraint of quorum sensing seems to avert PJI after TKA; 4) A recent in vitro study showed promising results in the prevention and management of PJI after TKA using PMMA [poly(methyl methacrylate)] loaded with up to 100 mg of rifampin. Level of evidence: III

Lactic acid bacteria produce various beneficial metabolites, including antimicrobial agents. Owing to the fast-rising antibiotic resistance among pathogenic microbes, scientists are exploring antimicrobials beyond antibiotics. In this study, we examined four Lactobacillus strains, namely L. plantarum 42, L. brevis 205, L. rhamnosus 239, and L. delbrueckii 263, isolated from healthy human microbiota, to evaluate their antibacterial and antifungal activity.

Lactobacillus strains were cultivated, and the conditioned media were obtained. The supernatant was then used to treat pathogenic bacteria and applied to the growth media containing fungal and bacterial strains. Additionally, the supernatant was separated to achieve the organic and aqueous phases. The two phases were then examined in terms of bacterial and fungal growth rates. Disk diffusion and MIC tests were conducted to determine strains with the most growth inhibition potential. Finally, the potent strains identified through the MIC test, were tested on the pathogenic microorganisms to assess their effects on the formation of pathogenic biofilms.

The organic phase of L. rhamnosus 239 extracts exhibited the highest antibacterial and antibiofilm effects, while that of L. brevis 205 demonstrated the most effective antifungal impact, with a MIC of 125 µg/mL against Saccharomyces cerevisiae.

This study confirms the significant antimicrobial impacts of the LAB strains on pathogenic bacteria and fungi; hence, they could serve as a reliable alternative to antibiotics for a safe and natural protection against pathogenic microorganisms.

Inappropriate management of textile wastewater results in environmental pollution. To counter this, biofilters or biofilm systems serve as alternatives. Biofilters work like a filter, with a media stack that aids in the filtration process. In this study, pozzolan and sawdust were used as media. The present study aimed to identify the difference in average color content, chemical oxygen demand (COD), and chromium of textile wastewater after passing through a single biofilter versus a combination biofilter.

This study employs a post-test with a control design experimental research design. The research population is the total textile wastewater produced by the X industry located in Cimahi city, Indonesia. The grab sampling technique was employed to collect 30 L of textile wastewater for each treatment using both the single biofilter (composed solely of sawdust) and the combination biofilter (mixture of sawdust and pozzolan).

There are significant differences in color, COD, and chromium content averages between single and combined biofilter treatments, supported by P values of 0.012, 0.004, and 0.010. The single biofilter exhibited higher percentage reductions in color and chromium (14.25% and 90.83%, respectively) compared to the combination biofilter. In contrast, the combination biofilter achieved a remarkable COD reduction of up to 79.45%compared to the single biofilter.

The results of the present study showed that the single biofilter had a higher capacity to remove color and chromium compared to the combination biofilter. Meanwhile, the combination biofilter was found to be more effective in removing COD compared to the single biofilter.

The current study aimed to investigate the control and treatment of biofilm-producing isolates of Pseudomonas aeruginosa using silicon nanoparticles (SiNPs).  Biofilm-producing isolates of P. aeruginosa were recovered from various food samples and identified through fluorescent green colony formation on selective and differential media, as well as the amplification of oprI and oprL genes. Tube methods, Congo-red agar method, and scanning electron microscopy (SEM) were used to study biofilm phenotypes. The effect of SiNPs was evaluated by broth dilution assay. The biofilm assay revealed that these isolates formed biofilms on glass surfaces within 72 hr of incubation. Scanning electron micrographs showed that the biofilm communities were composed of multicellular clusters of P. aeruginosa encased in matrix material. However, these isolates were unable to form biofilms on SiNPs-coated surfaces. The results showed that the planktonic isolates of P. aeruginosa were comparatively sensitive to the antibacterial properties of SiNPs, with minimum inhibitory concentration (MIC) ranging from 100 to 200 µg/ml. Contrarily, the biofilms were found to be 500 times more tolerant to the highest concentration of SiNPs (MIC of 500 µg/ml) and were more resistant. Under static conditions, the sedimentation of SiNPs resulted in their ineffectiveness. However, under shaking conditions, the biofilms were effectively dispersed and the cells were lysed. The results showed that SiNPs were effective against both the planktonic and the metabolically inactive forms of P. aeruginosa. This study suggests that SiNPs could be a useful tool for preventing the formation of biofilms and removing pre-existing biofilms.