scholarly journals Effect of Ciprofloxacin on the Growth and Biofilm Formation Ability of Staphylococcus aureus

2021 ◽  
pp. 44-59
Author(s):  
N. Queenette, Obinaju ◽  
C. Chukwunonyerem, Ogwunga ◽  
O. Sylvia, Anyadoh-Nwadike ◽  
U. Emmanuel, Nwakwasi
Keyword(s):  
Staphylococcus Aureus ◽  
Defense Mechanism ◽  
Bacterial Flora ◽  
Protein A ◽  
Inhibitory Effect ◽  
Phenotypic Characterization ◽  
Upper Respiratory Tract ◽  
Staphylococcal Infections ◽  
Superficial Skin ◽  
Time Kill

Staphylococcus aureus is part of the normal bacterial flora of the skin, intestine and upper respiratory tract of both humans and animals and has the potential of causing staphylococcal infections if there is a breach in the hosts’ defense mechanism. These infections could range from mild superficial skin infections to more severe and even fatally invasive diseases such as sepsis and toxic shock syndrome. The infectivity of S. aureus is attributed to its ability to withstand extreme conditions and its possession of various virulence factors. The aim of this project was to study the effect of ciprofloxacin on the growth and biofilm forming ability of CM10 strain of Staphylococcus aureus using time kill study, resazurin and live/dead staining of biofilms and Real-time polymerase chain reaction. The identity of the given CM10 strain was confirmed when the result of the API-Staph was in total accordance with the results obtained from the colony morphology and phenotypic characterization tests (Coagulase/protein A, Gram, and Catalase tests). CM10 strain of S. aureus was not susceptible to 0.25mg/L of ciprofloxacin used for the time kill experiment but was susceptible to a minimum inhibitory concentration of 0.5mg/L. The difference between the ciprofloxacin treated biofilms of CM10 strain and the untreated biofilms was significant (P<0.05) showing that ciprofloxacin has an adverse effect on the cells in the biofilm. The results of this study provide an insight on the growth as well as the biofilm forming ability of CM10 strain of Staphylococcus aureus. Ciprofloxacin has been shown to be an effective antibacterial against this strain of S. aureus by its inhibitory effect on the growth as well as biofilm forming ability of this strain of S. aureus.  This information would assist in developing novel anti-biofilm therapies to help in the management of biofilm mediated infections thereby reducing the morbidity and mortality rate of staphylococcal infections.

Phenotypic characterization and virulence of a sae−agr− mutant of Staphylococcus aureus

1996 ◽  
Vol 42 (2) ◽  
pp. 120-123 ◽  
Author(s):  
Ana T. Giraudo ◽  
Horacio Rampone ◽  
Aldo Calzolari ◽  
Rosa Nagel
Keyword(s):  
Staphylococcus Aureus ◽  
Parental Strain ◽  
Intraperitoneal Injection ◽  
Double Mutant ◽  
Protein A ◽  
Synergistic Interaction ◽  
Extracellular Protein ◽  
Phenotypic Characterization ◽  
Single Mutant

A sae::Tn551 agr::tetM double mutant was constructed and characterized. The production of several exoproteins (e.g., β-hemolysin, DNase, and proteases) by this mutant was determined and found to be lower than the already diminished production of either isogenic single mutant sae− or agr−. The double mutant also showed, like the agr− mutant, null production of α- and δ-hemolysins and diminished levels of lipase. The reduced levels of many exoproteins in the double mutant as compared with their already diminished levels in either single mutant suggest that there is an additive or synergistic interaction between the two mutations involved, sae− and agr−. However, inactivation of both loci, sae and agr, had a different effect on the two exoproteins that are up regulated in the agr− mutant; thus, coagulase dropped to levels close to the null levels of the sae− parental strain, while extracellular protein A displayed the high levels characteristic of the agr− single mutant. The virulence of the sae−agr− double mutant, determined by intraperitoneal injection in mice, was found to be significantly diminished as compared with that of the sae+agr+ parental strain or the sae−agr+ single mutant.Key words: Staphylococcus aureus, exoprotein expression, sae− mutant, agr− mutant.

scholarly journals The msaABCR Operon Regulates the Response to Oxidative Stress in Staphylococcus aureus

2019 ◽  
Vol 201 (21) ◽  
Author(s):  
Shanti Pandey ◽  
Gyan S. Sahukhal ◽  
Mohamed O. Elasri
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Defense Mechanism ◽  
Ex Vivo ◽  
Carotenoid Pigment ◽  
Content Type ◽  
Staphylococcal Infections ◽  
Organic Hydroperoxides

ABSTRACT Staphylococcus aureus has evolved a complex regulatory network that controls a multitude of defense mechanisms against the deleterious effects of oxidative stress stimuli, subsequently leading to the pathogen’s survival and persistence in the hosts. Previously, we characterized the msaABCR operon as a regulator of virulence, antibiotic resistance, and the formation of persister cells in S. aureus. Deletion of the msaABCR operon resulted in the downregulation of several genes involved in resistance against oxidative stress. Notably, those included carotenoid biosynthetic genes and the ohr gene, which is involved in resistance against organic hydroperoxides. These findings led us to hypothesize that the msaABCR operon is involved in resisting oxidative stress generated in the presence of both H2O2 and organic hydroperoxides. Here, we report that a protein product of the msaABCR operon (MsaB) transcriptionally regulates the expression of the crtOPQMN operon and the ohr gene to resist in vitro oxidative stresses. In addition to its direct regulation of the crtOPQMN operon and ohr gene, we also show that MsaB is the transcriptional repressor of sarZ (repressor of ohr). Taken together, these results suggest that the msaABCR operon regulates an oxidative stress defense mechanism, which is required to facilitate persistent and recurrent staphylococcal infections. Moving forward, we plan to investigate the role of msaABCR in the persistence of S. aureus under in vivo conditions. IMPORTANCE This study shows the involvement of the msaABCR operon in resisting oxidative stress by Staphylococcus aureus generated under in vitro and ex vivo conditions. We show that MsaB regulates the expression and production of a carotenoid pigment, staphyloxanthin, which is a potent antioxidant in S. aureus. We also demonstrate that MsaB regulates the ohr gene, which is involved in defending against oxidative stress generated by organic hydroperoxides. This study highlights the importance of msaABCR in the survival of S. aureus in the presence of various environmental stimuli that mainly exert oxidative stress. The findings from this study indicate the possibility that msaABCR is involved in the persistence of staphylococcal infections and therefore could be a potential antimicrobial target to overcome recalcitrant staphylococcal infections.

scholarly journals Study on Demethoxycurcumin as a promising approach to reverse methicillin-resistance of Staphylococcus aureus

2021 ◽  
Author(s):  
Qian-Qian Li ◽  
Ok-Hwa Kang ◽  
Dong-Yeul Kwon
Keyword(s):  
Staphylococcus Aureus ◽  
Atp Synthase ◽  
Methicillin Resistance ◽  
Synergistic Effects ◽  
Inhibitory Effect ◽  
Current Treatment ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Time Kill

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) has always been a thorny pathogen, posing serious threat to public health. Current treatment resort for MRSA infections is still scarce. Research on phytochemical component that can replace antibiotics with limited efficacy may be an innovative method to solve intractable MRSA infections. The present study was devoted to investigating the antibacterial activity of the natural compound demethoxycurcumin (DMC) against MRSA and exploring its possible mechanism for eliminating MRSA resistance. Methods The present study determined minimum inhibitory concentrations (MICs) of DMC, oxacillin, ampicillin and gentamicin against MRSA strains by the broth microdilution method. The synergistic effects of DMC and antibiotics were investigated by the checkerboard method and the time-kill assay. The membrane-permeabilizing agents and ATP synthase inhibitors were employed to explore their impact on the antibacterial ability of DMC. Western blot analysis and qRT-PCR were performed to detect the proteins and genes related to drug resistance and S. aureus exotoxins. Results The MIC of DMC against MRSA is 62.5 µg/ml by broth microdilution method. The synergy between DMC and gentamicin was confirmed by checkerboard method and time-kill assay. When ATP synthase inhibitors blocked the metabolic ability of bacteria, the antibacterial effect of DMC was enhanced. The production of penicillin-binding protein 2a (PBP2a) protein and related genes were reduced by DMC at sub-inhibitory concentrations. In addition, DMC hindered the translation of staphylococcal enterotoxin and the transcription of related gene. Conclusions Based on our results, DMC has a significant inhibitory effect on the vitality of MRSA, and it can be inferred that the mechanism by which DMC reverses MRSA resistance is related to the ability of DMC to block resistance determinants (PBP2a and β-lactamase) and S. aureus exotoxin. This study provides experimental evidences that DMC has the potential to be a candidate substance for the treatment of MRSA infections.

scholarly journals Emergence of a Staphylococcus aureus Clone Resistant to Mupirocin and Fusidic Acid Carrying Exotoxin Genes and Causing Mainly Skin Infections

2017 ◽  
Vol 55 (8) ◽  
pp. 2529-2537 ◽  
Author(s):  
Anastassios Doudoulakakis ◽  
Iris Spiliopoulou ◽  
Nikolaos Spyridis ◽  
Nikolaos Giormezis ◽  
John Kopsidas ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fusidic Acid ◽  
Protein A ◽  
Acid Resistance ◽  
Content Type ◽  
Staphylococcal Infections ◽  
Genes Encoding ◽  
Topical Antimicrobials ◽  
Resistant Strains ◽  
High Level

ABSTRACTSkin and soft tissue infections (SSTIs) caused by mupirocin-resistantStaphylococcus aureusstrains have recently increased in number in our settings. We sought to evaluate the characteristics of these cases over a 43-month period. Data for all community-acquired staphylococcal infections caused by mupirocin-resistant strains were retrospectively reviewed. Genes encoding products producing high-level resistance (HLR) to mupirocin (mupA), fusidic acid resistance (fusB), resistance to macrolides and lincosamides (ermCandermA), Panton-Valentine leukocidin (PVL) (lukS/lukF-PV), exfoliative toxins (etaandetb), and fibronectin binding protein A (fnbA) were investigated by PCRs in 102 selected preserved strains. Genotyping was performed by SCCmecandagrtyping, whereas clonality was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). A total of 437 cases among 2,137 staphylococcal infections were recorded in 2013 to 2016; they were all SSTIs with the exception of 1 case of primary bacteremia. Impetigo was the predominant clinical entity (371 cases [84.9%]), followed by staphylococcal scalded skin syndrome (21 cases [4.8%]), and there were no abscesses. The number of infections detected annually increased during the study years. All except 3 isolates were methicillin susceptible. The rates of HLR to mupirocin and constitutive resistance to clindamycin were 99% and 20.1%, respectively. Among the 102 tested strains, 100 (98%) weremupApositive and 97 (95%) werefusBpositive, 26/27 clindamycin-resistant strains (96.3%) wereermApositive, 83 strains (81.4%) werelukS/lukFpositive, 95 (93%) carried bothetaandetbgenes, and 99 (97%) werefnbApositive. Genotyping of methicillin-sensitiveS. aureus(MSSA) strains revealed that 96/99 (96.7%) belonged to one main pulsotype, pulsotype 1, classified as sequence type 121 (ST121). The emergence of a single MSSA clone (ST121) causing impetigo was documented. Resistance to topical antimicrobials and a rich toxinogenic profile confer to this clone adaptability for spread in the community.

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