Screening of Molecular Virulence Markers in Staphylococcus aureus and Pseudomonas aeruginosa Strains Isolated from Clinical Infections (original) (raw)
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African Journal of Microbiology Research, 2013
Considering the great diversity and prevalence of opportunistic pathogens as well as the medical consequences arising from increasingly frequent cases of infections with resistant pathogens, the aim of this study was to analyze and compare the virulence profiles of some recent isolates of the most frequently encountered human pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. We screened for the production of seven soluble virulence factors (hemolysins, caseinases, amylases, DNA-se, gelatinase, lipase and lecithinase) in 181 clinical isolates, using a method of culturing on specific substrates. Adherence to host cells was analyzed using Cravioto's adapted method, and invasive potentials were established by an antibiotic protection assay. The results demonstrated that these pathogens may act differently when they are the protagonists of infections and may occur in different clinical condition. We revealed that the analyzed strains display different patterns of soluble virulence factors and different invasive capacity, according to the isolation source; many of the observed differences are statistically significant. By investigating the development of infectious process in various clinical conditions, our studies provide a high contribution to the development of personalized anti-infectious therapies.
Pseudomonas aeruginosa and Staphylococcus aureus virulence factors as biomarkers of infection
Biological Chemistry
The gold standard for the diagnosis of bacterial infections in clinical samples is based on culture tests that are time-consuming and labor-intense. For these reasons, an extraordinary effort has been made to identify biomarkers as the tools for sensitive, rapid and accurate identification of pathogenic microorganisms. Moreover, biomarkers have been tested to distinguish colonization from infection, monitor disease progression, determine the clinical status of patients or predict clinical outcomes. This mini-review describes Pseudomonas aeruginosa and Staphylococcus aureus biomarkers, which contribute to pathogenesis and have been used in culture-independent bacterial identification directly from patient samples.
Molecular Microbiology, 2021
Pseudomonas aeruginosa (Pa) and Staphylococcus aureus (Sa) are opportunistic pathogens that are most commonly co-isolated from chronic wounds and the sputum of cystic fibrosis patients. Over the last few years, there have been plenty of contrasting results from studies involving P. aeruginosa and S. aureus co-cultures. The general concept that P. aeruginosa outcompetes S. aureus has been challenged and there is more evidence now that they can co-exist. Nevertheless, it still remains difficult to mimic polymicrobial infections in vitro and in vivo. In this review, we discuss recent advances in regard to Pa-Sa molecular interactions, their physical responses, and in vitro and in vivo models. We believe it is important to optimize growth conditions in the laboratory, determine appropriate bacterial starting ratios, and consider environmental factors to study the coexistence of these two pathogens. Ideally, optimized growth media should reflect host-mimicking conditions with or without host cells that allow both bacteria to co-exist. To Accepted Article This article is protected by copyright. All rights reserved further identify mechanisms that could help to treat these complex infections, we propose to use relevant polymicrobial animal models. Ultimately, we briefly discuss how polymicrobial infections can increase antibiotic tolerance.
A review of virulence factors, pathogenesis, and antibiotic resistance in Staphylococcus aureus
Reviews in Medical Microbiology, 2016
Staphylococcus aureus is a common pathogen associated with serious community and hospital-acquired diseases and has long been considered as a major problem of public health. This potent Gram-positive bacterium is able to bypass all barriers of the host defense system as it possesses a wide spectrum of virulence factors. S. aureus is also one of the prominent pathogens in biofilm-related infections of indwelling medical devices, which are responsible for billions in healthcare cost each year in the United States. S. aureus expresses a large number of virulence factors that are implicated in their pathogenesis. Methicillin-resistant S. aureus infections have reached epidemic levels in many parts of the world. This review describes the virulence factors, pathogenesis, and antibiotic resistance in S. aureus.
Cellular and Molecular Biology
Pseudomonas aeruginosa (P. aeruginosa) is considered as the foremost cause of hospital-acquired infections due to its innate and plasmid-mediated resistance to multiple antibiotics making it a multi-drug resistant (MDR) pathogen. This study aimed to determine the biofilm formation ability and the presence of different virulence factors genes (pslA, pelA, exoS, toxA and algD) among biofilm-forming strains of P. aeruginosa clinical isolates from burn units in Ismailia Hospitals, Egypt. In our cross-sectional study, one hundred and twenty-six (126) non-duplicate clinical P. aeruginosa isolates were recovered from 450 clinical specimens from burn units in Ismailia Hospitals. The antibiotic sensitivity of strong and moderate biofilm producer isolates was investigated using the disc diffusion method. The isolated bacteria were tested for their ability to form biofilm using a microtiter plate assay. The expression of (pslA, pelA, exoS, toxA and algD) genes in biofilm producers isolates was detected using PCR. The MPA detected 80% (95 /126) isolates as biofilm producers, 18% (22/126) were strong biofilm producers, 34% (43/126) were moderate biofilm producers, 28% (35/126) were weak biofilm producers and 20% (31/126) non-biofilm producers. Susceptibility pattern analysis of biofilm-forming P. aeruginosa isolates (95) detected that 60% (68/ 95) were multi-drug resistant isolates (MDR). Resistance to all used antibiotics and multidrug resistance was higher among biofilm-producing than non-biofilm-producing strains, but the difference was statistically non-significant. Investigation of virulence factors associated genes revealed that 96%, 94%, 86.4%, 80.0% and 74% of the biofilm producers isolates were harboring algD, pslA, pel A, toxA and exoS gene, respectively. The present study confirmed that antimicrobial resistance and virulence genes were more prominent in biofilm-producing P. aeruginosa than in non-biofilm-producers.
Comparison of Virulence Factors in Clinical Isolates and Standard Strain of Staphylococcus aureus
Staphylococcus aureus is an important human bacterial pathogen causing wide range of diseases both by nosocomial and community-acquired infections. The organism produces a number of virulent toxins and proteins which are responsible for serious infections damaging host cells and tissues thereby involving in pathogenesis. Due to the continuous use of antibiotics, the organism show resistant to most of the available antibiotics and thereby creating a major problem and threaten to human and public health. In this present study, six S. aureus strains and clinical isolates (S1, S2, C1, C2, S2 Mut and MTCC 737) were compared for the antibiotics susceptibility test in which all the strains were found to be resistant to one of the most important antibioticsvancomycin. Plasmid curing analysis was done to know if the antibiotic resistance was plasmid-mediated or chromosome-mediated. The result showed the presence of zone of inhibition even after treating the strains with acridine orange thus inferring it as chromosome mediated. The strains were assayed for the activity of three important virulence factors produced by the organism such as protease, lipase and biofilms by plate assays which have specific roles in causing disease in host. The results showed that among the six tested strains the clinical isolate C1 and MTCC strain were found to be more virulent since all the three studied virulence factors lipase, protease and biofilm were produced in them when compared to other strains S1, S2 C2 and S2 mut.
Staphylococcus Aureus [Working Title]
Methicillin-resistant Staphylococcus aureus (MRSA) strains are known for their emergent multi-drug resistance phenotypes, implication in nosocomial infections and outbreaks worldwide, being commonly associated with hospital-acquired MRSA (HA-MRSA) and community-acquired MRSA (CA-MRSA) skin and soft tissue infections. S. aureus causes a wide spectrum of clinical symptoms, ranging from mild to life-threatening diseases; disease severity is determined by microorganism-related virulence factors and host condition. The ability of these strains to form microbial biofilms, one of the main pathogenicity factors, generates difficult medical problems, favored by the widespread use of large invasive medical procedures (probes, catheters, heart valves, prostheses). Contamination of these devices is associated with the risk of subsequent development of human infections. The knowledge of virulence and antibiotic resistance patterns of HA-MRSA and CA-MRSA and encoding genes are very important for supporting effective infection control measures and therapy of staphylococcal infections.
Contribution of an arsenal of virulence factors to pathogenesis of Pseudomonas aeruginosa infections
Annals of Microbiology, 2011
Pseudomonas aeruginosa is an increasingly prevalent opportunistic pathogen that causes a variety of nosocomial infections, life-threatening diseases in immunocompromised persons and chronic pulmonary infections in cystic fibrosis patients. The organism's virulence depends on an arsenal of cell-associated and extracellular factors determining the pathogenesis of infections as multifactorial. Most P. aeruginosa infections are both invasive and toxinogenic. Many of the extracellular virulence factors (proteases, exotoxin A, pyocyanin, siderophores, hemolysins) required for tissue invasion and dissemination of P. aeruginosa are controlled by quorum sensing (QS) that enable the bacteria to produce these factors in a coordinated, cell-density-dependent manner and overwhelm the host defense mechanisms during acute infection. Sometimes, QS also contributes to biofilm formation and thus participates in pathogenesis of chronic infection. This system is recognized to be a global regulatory network controlling the expression of a large number of virulence genes either directly or indirectly. Two-component sensor kinases such as RetS, LadS and GacS are also controlling the production of virulence factors as well as the switch from acute to chronic infection. The present review describes the known virulence determinants of P. aeruginosa, the stages of infection as well as the importance of QS in the pathogenesis of P. aeruginosa infection.
BMC Infectious Diseases, 2021
Background and objective Carriage of virulence factors confers some evolutionary benefit to bacteria, which favors the resistant strains. We aimed to analyze whether antibiotic susceptibility of Staphylococcus aureus strains is affected by agr typing, biofilm formation ability, and virulence profiles. Methods A total of 123 S. aureus clinical isolates were subjected to antimicrobial susceptibility testing by disk diffusion method, biofilm formation by microtiter plate method, as well as polymerase chain reaction screening to identify virulence genes and the accessory gene regulator ( agr ) types I-IV. A P value < 0.05 was considered significant. Results The most prevalent virulence gene was staphyloxanthin crtN , followed by hemolysin genes, capsular cap8H , toxic shock toxin tst , and enterotoxin sea , respectively. Resistant isolates were more commonly found in the agr -negative group than in the agr -positive group. Isolates of agr type III were more virulent than agr I isola...