Biofilm image of Methicillin-resistant Staphylococcus aureus (2023)


Methicillin-resistentStaphylococcus aureus(MRSA) is one of the main causes of antibiotic resistance. The incidence of MRSA is increasing worldwide. Reports from intensive care units (ICUs) in the United States showed an increase in MRSA from 36% in 1992 to 64.5% in 2003 (Klevens et al., 2006). In Europe, the prevalence is between 1 and 50%. Johnson et al. reported in 2005 an increase in MRSA prevalence from 2% in 1990 to 43% in 2002 in the United Kingdom (UK), while prevalence in the Netherlands was low and remained at 5% (Johnson et al., 2005). Morbidity and mortality from MRSA infection in the UK increased between 1993 and 2002 (Crowcroft and Catchpole, 2002). MRSA infections lead to long hospital stays and higher costs (Cosgrove et al., 2005). Surveillance programs seem necessary, such as the European Antimicrobial Resistance Surveillance System (EARSS), which monitors the seven most invasive bacteria responsible for antimicrobial resistance ( In 1993, Australia reported the occurrence of the first MRSA in the community (Udo et al., 1993). Reports of four MRSA resulting in child deaths in the community followed (Centers for Disease Control and Prevention, 1999). Community prevalence of MRSA is now reported worldwide (Borer et al., 2002; Aires de Sousa et al., 2005). Thus, there is a shift in the epidemiology of community- and hospital-associated MRSA worldwide.

Chronic nosocomial infectionsS aureushas become a major problem in recent years with the increasing use of prosthetic biomedical implants. Chronic infection of a prosthetic implant could serve as a septic focus leading to osteomyelitis, acute sepsis and death, especially in immunocompromised patients (Heilmann et al., 1998). Bacteria colonize prosthetic implants as a biofilm, i.e. H. in the form of several layers of fixed cells that adhere both to the implant surface and to each other. Once a biofilm is formed, it can be very difficult to treat clinically, as the bacteria in the biofilm are well protected from the host's immune response and antibiotics (Hoyle and Costerton, 1991).

Polysaccharide intracellular adhesion (PIA) is a regulator of biofilm formation mediated by cell-to-cell adhesion and is the gene product oficaADBC(Ammendolia et al., 1999). The intercellular adhesion site (ica), consisting oficaADBCGenes encoding proteins that mediate synthesis of PIA and polysaccharide/adhesin PS/A in staphylococcal species (OGara and Humphreys, 2001). BelowicaGen,icaCAndicaDThey have been reported to play an important role in biofilm formationS aureusAndS. epidermidis(Yazdani et al., 2006).

Therefore, our objective was to determine the ability of clinical MRSA isolates to produce biofilms by assessmenticaDAndicaa.

sectional cuts

Bacteria isolate

Between March 2013 and January 2014, 26 clinical MRSA isolates were identified in Ilam hospitals in Iran.MRSAClinical isolates were isolated from lesions, sputum, bloodstream and urinary tract infections (Table 1).

Staphylococcus aureusIdentification

Isolates were grown on blood agar and incubated at 35°C for 24 hours. Individual colonies of each isolate were scored by Gram stain. Subsequently, Gram-positive cocci were tested for catalase tube test (CTT), oxidase, growth on monnitol salt agar (MSA) and DNase activity (Winn et al., 2006).

Staphylococcus aureusIdentification

Gram-positive, short-chain or cluster cocci were examined and further analysis performed. As bacteria, catalase positive, oxidase negative, growth on MSA using mannitol, coagulation positive and DNase activity were consideredS aureus.

MRSA identification

Isolates resistant to oxacillin were subjected to PCR. The PCR results showed thatmecAThe gene was present in all putative MRSA strains, consistent with disc diffusion results. MRSA positivemecAshowed a clear band with a size of 574 bp (Fig. 1).

icaDwas responsible for biofilm formation in MRSA clinical isolates from Ilam hospitals in Iran



Bacterial adhesion factor is considered a virulence factor that plays an important role in infections associated with catheters and other medical devices (Francois et al., 1996). The ability toS aureusSettlement in artificial material involves two main mechanisms. Firstly, the production of polysaccharide glue and secondly, the presence of adhesions for the host matrix proteins adsorbed to the surface of the biomaterial (Montanaro et al., 1998). If the biopic

CRediT author contribution statement

Maryam Mohamadian collected the samples and performed the PCR. Sobhan Ghafourian designs the primers. Nourhoda Sadeghifard made the identification. Iraj Pakzad performed the electrophoresis, Behzad Badakhsh wrote and edited the manuscript.

Statement of competing interests

There is no conflict of interest.


The current research was supported byIlam University of Medical Scienceswith scholarship no.951027/148.

Selected articles (6)

  • Research Article

    Choroidal thickness of children's eyes with anisometropic and strabismic amblyopia

    Journal of American Association for Pediatric Ophthalmology and Strabismus, Band 19, Ausgabe 3, 2015, S. 237-241

    Comparison of the choroidal thickness of eyes of children with amblyopia due to strabismus or anisometropia with the fellow eye and age-matched controls.

    This cross-sectional study included 40 patients with anisometropic amblyopia, 40 patients with strabismic amblyopia, and 40 age-matched controls. Choroidal thickness was measured in all patients and controls using the spectral domain depth imaging technique of optical coherence tomography. The choroidal thickness was measured in the subfoveal area and at distances from 500 μm to the nose and temporally to the fovea up to 2000 μm. Measurements were compared between the three groups.

    The mean age was 7.9 ± 2.6 years (range 4-13 years) in the anisometropic group, 9.0 ± 3.7 years (range 4-15 years) in the strabismus group and 8.4 ± 2.6 years (range 4-15 years) in the control group. The mean subfoveal choroidal thickness in the anisometropic group was 362 ± 82 μm in the amblyopic eyes and 301 ± 54 μm in the fellow eyes; in the strabismus group, 413 ± 82 µm in the amblyopic eyes and 316 ± 54 µm in the other eyes. The mean subfoveal choroidal thickness was 310 ± 78 μm in the control eyes. The subfoveal choroids in both the anisometropic and strabismic amblyopic eyes were significantly thicker than those in the fellow eyes in the corresponding groups and the control eyes (P< 0.05 for all).

    The subfoveal choroid in eyes with anisometropic and strabismic amblyopia is significantly thicker than in the fellow eye and age-matched controls.

  • Research Article

    Determination of the lag times of individual cells of Cronobacter spp. Strains exposed to different stress conditions: impact on recognition

    International Journal of Food Microbiology, Band 236, 2016, S. 161-166

    The variation in stress resistance and lag time of individual cells can greatly influence their growth and thus the likelihood of their detection in food. In this study, six strains ofCronobactersp. were subjected to heat, acid, and desiccation stress, and the lag times of individual cells were determined using optical density measurements. The duration of the lag time was highest after acid loading and did not correlate with voltage resistance. The effect that inactivation caused by stress and a longer lag time had on the predicted CFU value after enrichment were simulated in different scenarios. For most strains, an enrichment time of 18 hours was sufficient for the stressed cells to reach the minimum recommended cell inoculum levelCronobacterScreening broth detection. Certain strains may lead to longer recovery periods. Furthermore, probability calculations showed that the number of samples taken from a lot can have a significant impact on the probability of detection, especially at low contamination rates. Therefore, in addition to increasing the recovery time, increasing the number of samples is a suitable strategy to improve detection.

  • Research Article

    Inactivation of undried and dried Cronobacter Sakazakii and Salmonella spp. at low and high inoculum concentrations in reconstituted infant formula with vanillin

    Food Control, Band 50, 2015, pp. 850-857

    Cronobacter sakazakiiAndsalmonellafound in small amounts in infant formula and survives desiccation. They are known to accumulate in reconstituted infant formula to infectious levels and cause severe illness in newborns. In this study, the minimal inhibitory (MIC) and bactericidal (MBC) concentrations of vanillin were determined against undried and dried cocktailsC. sakazakiiAndsalmonellaat 4, 10 and 23°C at quarter strength TSBYE. Next, the antimicrobial activity of several vanillin concentrations was tested against undried and dried cells at high and low inoculum concentrations in reconstituted infant formula (IMF) at 4, 10 and 23 °C. The results showed that it had not dried outC. sakazakiiAndsalmonellawere more susceptible to vanillin than dried cells at 4, 10 and 23 °C in ¼ TSBYE. At high inoculum concentrations, vanillin inhibited the growth of undried plantsC. sakazakiiAndsalmonellain reconstituted IMF at 4, 10 and 23°C, but inhibited the growth of desiccated cells at 10 and 23°C. At low inoculum levels, vanillin inhibited the growth of undried and dried plantssalmonellaat 4, 10 and 23 °C, but is inhibited without drying outC. sakazakiiat 4, 10 and 23°C and inhibited desiccated cells at 23°C. In general, the inhibitory effect of vanillin against low inoculum was greater than that against high inoculum in undried and dried plantsC. sakazakiiAndsalmonella. Therefore, using vanillin as an antimicrobial additive may provide some controlC. sakazakiiAndsalmonellai IMF.

  • Research Article

    Comparative proteomic analysis of Cronobacter sakazakii isolates with different virulence

    Journal of Proteomics, Band 128, 2015, S. 344-351

    Cronobacteris a genus of widespread, opportunistic foodborne pathogens that can cause severe illness in vulnerable infants who have immature immunity and are heavily dependent on powdered infant formula, one of the most commonly contaminated foods with this pathogen. However, only limited information is available on the pathogenesis and the specific virulence factors of this species. In this study, the virulences of 42 were investigatedCronobacter sakazakiiIsolates were analyzed by infecting newborn SD rats. A comparison of the type pattern of the isolates enabled the identification of groups with close family relationships but with different pathogenesis. Among these groups, two strains belonging to the same group but showing different virulences were selected and 2-DE was used to identify differentially expressed proteins, focusing on virulence-related proteins. A total of 111 protein spots were identified using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS), and 89 were successfully identified. Further analysis suggested that at least 11 of these proteins may be involved in the pathogenesis of this pathogen. Real-time PCR was performed to further confirm the differential expression pattern of the genes. The results showed that the mRNA expression levels matched the protein expression levels.

    The virulence factors and pathogenesis ofCronobacterare largely unknown. In combination with toxicological animal tests and subtyping results fromC. sakazakiiA comparative proteomic analysis was performed to assess the differentially expressed proteins of two isolates that exhibited different virulence but were closely related. These methods enabled the identification of virulence-related factors ofCronobacter. At least 11 of the 89 identified proteins have a virulence-related potential. This work provides comprehensive candidates for further investigation into the pathogenesis ofCronobacter.

  • Research Article

    Related structures of Cronobacter dublinensis G3983 and G3977 O-polysaccharides containing 3-(N-acetyl-1-alanyl)amino-3,6-dideoxy-d-galactose

    Carbohydrate Research, Band 404, 2015, S. 132-137

    Cronobactersp. are newly emerging opportunistic human pathogens associated with life-threatening infections, particularly in neonates. O-antigen (O-polysaccharide) is highly variable and plays an important role in virulence and niche adaptation. In this work, short-chain O-polysaccharides consisting of an average of 2-3 repeating units were obtained by slightly acidic or slightly alkaline degradation of the lipopolysaccharides ofC. dublinensisG3983 and G3977 and examined by compositional analysis, Smith digestion and1Hand13C NMR spectroscopy. The following structures of the O-polysaccharides were determined:

    where R indicates H in strain G3983 or a-.D-GlcPi stamme G3977,D-Fuc3NAlaAc shows 3-(N-Acetyl-l-alanyl)amino-3,6-didesoxy-D- galactose. Both strains share the O antigen gene cluster identicallyC. dublinensisO1 (Foodborne pathogens. Haze. 2013,10343-352). The assigned gene functions are consistent with the O antigen structure ofC. dublinensisG3983 and side chain glucosylation of the O antigen ofC. dublinensisG3977 is apparently encoded elsewhere in the genome.

  • Research Article

    Synthetic instructions for the acidic hexasaccharide repeat unit of Cronobacter sakazakii HPB 2855 O-antigen using a one-pot glycosylation

    Tetrahedron Letters, Volume 60, Issue 3, 2019, pp. 230–234

    Synthesis of a hexasaccharide repeating unit desÖ-antigen ofCronobacter sakazakiiHPB 2855 was obtained by sequential glycosylation and one-pot glycosylation-deprotection techniques. The synthetic method relies on the use of aP-Methoxybenzylether alson page-Removable protective group to significantly reduce the number of reaction steps. All glycosylations were performed by activating the only class of simple and stable thioglycosyl donors using NIS in the presence of silica-immobilized sulfuric acid (H2SO4-silica) as a Bronsted acid catalyst to act as a promoter. The stereo results of all glycosylation steps were excellent and the yields were satisfactory. The TEMPO-mediated selective oxidation of the primary hydroxyl group was performed late in the synthetic strategy to access the required uronic acid motif.

© 2020 Elsevier Inc. All rights reserved.

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