Mupirocin-Resistant Staphylococcus aureus in Iran: A Biofilm Production and Genetic Characteristics

The spread of mupirocin-resistant Staphylococcus aureus strains in hospitals and communities is a universal challenge. Limited data is available on the genetic features of high-level mupirocin resistant- (HLMUPR-) S. aureus isolates in Tehran. In the present research, we investigated 48 high-level mupirocin resistance S. aureus by antimicrobial activity, virulence analysis, biofilm formation, multilocus sequence typing (MLST), and staphylocoagulase (SC) typing. All the HLMUPR strains were positive for mupA gene. The frequency of multidrug resistance was 97.9%. Twenty-one (43.8%) were toxinogenic with 14 producing pvl (29.2%), 5 tst (10.4%), and two eta (4.2%). Among the HLMUPR isolates, biofilm production was detected in 45 (89.6%) isolates with complete dominance clfB, clfA genes, and a noticeably high frequency fnbA (95.8%), followed by fnbB (93.8%), eno and icaD (each 83.3%), sdrC (81.3%), ebps (79.2%), icaA (75%), sdrD (66.7%), fib (60.4%), sdrE (50%), cna (41.7%), and bap (4.2%). Coagulase typing distinguished isolates into four genotypic patterns including III (50%), II (27.1%), and type IVa (22.9%). A total of three clonal complexes (CCs) and 4 sequence types (STs) including CC/ST22 as the most prevalent (52.1%), CC8/ST239 (20.8%), CC/ST8 (16.7%), and CC/ST5 (10.4%) were identified in current work. According to our analysis, nonbiofilm producer isolates belonged to CC8/ST239 (6.3%) and CC/ST8 (4.2%). Fusidic acid-resistant isolates belonged to CC/ST45 ( n = 3 ) and CC8/ST239 ( n = 1 ). Observations highlighted the circulation of the CC/ST22 HLMUPR S. aureus strains with strong biofilm-production ability in our hospitals, indicating the possibility of transmission of this type between community and hospital.

Correlation of biofilm production with antibiotic susceptibility pattern of Pseudomonas aeruginosa from various clinical specimens

Background: Pseudomonas aeruginosa is one of the most prevalent nosocomial pathogens that cause a life-threatening infection. One of the important characteristics of P. aeruginosa is biofilm formation which leads to antibiotic resistance. Aims and Objectives: The aim of the study was to study the antibiotic resistance pattern of P. aeruginosa isolates and correlation with their biofilm-production. Materials and Methods: A total of 87 P. aeruginosa isolates from different clinical specimens were processed and confirmed by conventional microbiological methods as per standard methodology. Antibiotic sensitivity testing was done for all isolates. Biofilm producing isolates were identified by the microtiter plate method (MTPM). Results: Of 87 P. aeruginosa isolates, majority were from pus 33 (38%), followed by urine 26 (30%), sputum 19 (22%), body fluids 7 (8%), and blood 2 (2%). Biofilm producing isolates showed more resistance in comparison to non-biofilm producers. The observed difference between biofilm formation for multidrug resistant and susceptible isolates was found to be statistically significant. Conclusion: MTPM method was an effective test for detection of biofilm formation and was also able to verify biofilm production by P. aeruginosa. This indicated a higher propensity among the clinical isolates of P. aeruginosa to form biofilm and revealed a positive correlation between biofilm formation and antibiotic resistance. This indicates the need for testing of even susceptible isolates for virulence factors such as biofilm production.

Temperature-Dependent Influence of FliA Overexpression on PHL628 E. coli Biofilm Growth and Composition

Biofilm growth and survival pose a problem in both medical and industrial fields. Bacteria in biofilms are more tolerant to antibiotic treatment due to the inability of antibiotics to permeate to the bottom layers of cells in a biofilm and the creation of altered microenvironments of bacteria deep within the biofilm. Despite the abundance of information we have about E. coli biofilm growth and maturation, we are still learning how manipulating different signaling pathways influences the formation and fitness of biofilm. Understanding the impact of signaling pathways on biofilm formation may narrow the search for novel small molecule inhibitors or activators that affect biofilm production and stability. Here, we study the influence of the minor sigma transcription factor FliA (RpoF, sigma-28), which controls late-stage flagellar assembly and chemotaxis, on biofilm production and composition at various temperatures in the E. coli strain PHL628, which abundantly produces the extracellular structural protein curli. We examined FliA’s influence on external cellular structures like curli and flagella and the biomolecular composition of the biofilm’s extracellular polymeric substance (EPS) using biochemical assays, immunoblotting, and confocal laser scanning microscopy (CLSM). At 37°C, FliA overexpression results in the dramatic growth of biofilm in polystyrene plates and more modest yet significant biofilm growth on silica slides. We observed no significant differences in curli concentration and carbohydrate concentration in the EPS with FliA overexpression. Still, we did see significant changes in the abundance of EPS protein using CLSM at higher growth temperatures. We also noticed increased flagellin concentration, a major structural protein in flagella, occurred with FliA overexpression, specifically in planktonic cultures. These experiments have aided in narrowing our focus to FliA’s role in changing the protein composition of the EPS, which we will examine in future endeavors.

A study of biofilm production and antimicrobial susceptibility pattern among urinary isolates

Urinary tract infection (UTI) is the most commonly acquired bacterial infection. Bacterial biofilms play an important role in urinary tract infections and are responsible for persistent infections as well as higher antimicrobial resistance. The microbial biofilms pose a public health problem as the microorganisms in the biofilms are difficult to treat with antimicrobial agents. So the present study was undertaken with the aim to study biofilm production and antimicrobial susceptibility pattern of urinary isolates. Aerobic bacterial isolates from urine samples submitted to microbiology laboratory for culture were included in the study. The isolates were tested for biofilm formation by Congo red agar method and Christensen tube method. Antimicrobial susceptibility tests were performed on these isolates by Kirby Bauer disk diffusion method as per CLSI guidelines. A total of 293 Gram negative bacilli and 59 Gram positive cocci were tested for biofilm production and antimicrobial susceptibility testing. : Gram‑negative organisms were predominant (83.24%) of all the isolates. Biofilm production was detected in 47% of the isolates. 51.7%), were the most common biofilm producing Gram negative bacilli followed by (44.32%). Amongst Gram positive cocci, (77.8%) was the most common biofilm producing organism. Biofilm producing urinary isolates displayed relatively less percentage of antimicrobial susceptibility than biofilm non producers. Biofilm forming isolates showed higher antimicrobial resistance as compared to biofilm non producer. Early detection of biofilm production in urinary isolates may aid clinicians in treatment of urinary tract infections.

Evaluation of cell surface hydrophobicity and biofilm formation as pathogenic determinants among ESBL producing uropathogenic Escherichia coli

The attachment of the bacteria to the host cell and ability to invade the cell are regarded as important steps in the infectious process. The hydrophobicity of the microbial surface plays a critical role in the adherence of bacteria to the surface. The ability of biofilm formation can increase survival chance of microorganism, as cell growing in biofilm are highly resistant to the components of the immune system and many antimicrobial agents. Infection caused by ESBL- producers are associated with severe adverse outcomes and may be related to increased virulence of these strains.: A total of 100 urinary were selected for the study, of which 50 strains were from ESBL producers and 50 from non- ESBL-producing uropathogenic(UPEC) strains. The urinary isolates that were resistant to at least one of the three indicator cephalosporins (cefotaxime, cefpodoxime and ceftazidime) were tested for ESBL production by quantitative E-strip method. All the 100 urinary strains were tested for cell surface hydrophobicity (CSH) by salt aggregation method and Biofilm production by tissue culture plate method.Among ESBL producers, 19 (38%) were CSH positive and 34 (68%) were biofilm producers. However among non-ESBL producers, 05 (10%) were CSH positive and 12 (24%) were biofilm producers. Statistically significant difference (<0.001) was seen in the occurrence of CSH and biofilm production between ESBL and non ESBL producing UPEC isolates.In the present study, it was found that the ESBL producing isolates had a higher ability to form biofilm and CSH; both of them are among the important virulence factors associated with cell surface adherence which is the first step in bacterial infection.

Zinc Exposure Promotes Commensal-to-Pathogen Transition in Pseudomonas aeruginosa Leading to Mucosal Inflammation and Illness in Mice

The opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa) is associated gastrointestinal (GI) inflammation and illness; however, factors motivating commensal-to-pathogen transition are unclear. Excessive zinc intake from supplements is common in humans. Due to the fact that zinc exposure enhances P. aeruginosa colonization in vitro, we hypothesized zinc exposure broadly activates virulence mechanisms, leading to inflammation and illness. P. aeruginosa was treated with excess zinc and growth, expression and secretion of key virulence factors, and biofilm production were determined. Effects on invasion, barrier function, and cytotoxicity were evaluated in Caco-2 cells co-cultured with P. aeruginosa pre-treated with zinc. Effects on colonization, mucosal pathology, inflammation, and illness were evaluated in mice infected with P. aeruginosa pre-treated with zinc. We found the expression and secretion of key virulence factors involved in quorum sensing (QS), motility (type IV pili, flagella), biosurfactants (rhamnolipids), toxins (exotoxin A), zinc homeostasis (CzcR), and biofilm production, were all significantly increased. Zinc exposure significantly increased P. aeruginosa invasion, permeability and cytotoxicity in Caco-2 cells, and enhanced colonization, inflammation, mucosal damage, and illness in mice. Excess zinc exposure has broad effects on key virulence mechanisms promoting commensal-to-pathogen transition of P. aeruginosa and illness in mice, suggesting excess zinc intake may have adverse effects on GI health in humans.

Inducible Clindamycin Resistance and Biofilm Production among Staphylococci Isolated from Tertiary Care Hospitals in Nepal

Resistance to antibiotics, biofilm formation and the presence of virulence factors play important roles in increased mortality associated with infection by staphylococci. The macrolide lincosamide streptogramin B (MLSB) family of antibiotics is commonly used to treat infections by methicillin-resistant isolates. Clinical failure of clindamycin therapy has been reported due to multiple mechanisms that confer resistance to MLSB. This study aims to find the incidence of different phenotypes of MLSB resistance and biofilm production among staphylococci. A total of 375 staphylococci were isolated from different clinical samples, received from two tertiary care hospitals in Nepal. Methicillin resistance was detected by cefoxitin disc diffusion method and inducible clindamycin resistance by D test, according to CLSI guidelines. Biofilm formation was detected by the tissue culture plate method and PCR was used to detect ica genes. Of the total staphylococci isolates, 161 (42.9%) were Staphylococcus aureus, with 131 (81.4%) methicillin-resistant strains, and 214 (57.1%) isolates were coagulase-negative staphylococci, with 143 (66.8%) methicillin-resistant strains. The overall prevalence of constitutive MLSB (cMLSB) and inducible MLSB (iMLSB) phenotypes was 77 (20.5%) and 87 (23.2%), respectively. Both iMLSB and cMLSB phenotypes predominated in methicillin-resistant isolates. The tissue culture plate method detected biofilm formation in 174 (46.4%) isolates and ica genes in 86 (22.9%) isolates. Among biofilm producing isolates, cMLSB and iMLSB phenotypes were 35 (20.1%) and 27 (15.5%), respectively. The cMLSB and iMLSB were 11 (12.8%) and 19 (22.1%), respectively, in isolates possessing ica genes. Clindamycin resistance in the form of cMLSB and iMLSB, especially among MRSA, emphasizes the need for routine D tests to be performed in the lab.