Genomic and Therapeutic Analyses of Staphylococcus aureus Isolated from Cattle Reproductive Tract.

Staphylococcus aureus is emerging as a ubiquitous multidrug-resistant pathogen circulating among animals, humans, and their environment. The current study focused on molecular epidemiology and evidence-based treatment against S. aureus from bovine endometritis. For this study, n = 304 cattle were screened for endometritis using ultrasonography while presenting case history, and clinical signs were also considered. S. aureus was isolated from endometritis-positive uterine samples which were further put to molecular identification, phylogenetic analysis, susceptibility to antibiotics, and testing of novel drug combinations in both in vitro and field trials. The findings of the study revealed 78.20% of bovine endometritis samples positive for S. aureus, while nuc gene-based genotyping of S. aureus thermal nuclease (SA-1, SA-2, and SA-3) showed close relatedness with S. aureus thermal nuclease of Bos taurus. Drug combinations showed 5.00 to 188.88% rise in zones of inhibitions (ZOI) for drugs used in combination compared to the drugs used alone. Gentamicin in combination with amoxicillin and enrofloxacin with metronidazol showed synergistic interactions in an in vitro trial. Co-amoxiclav with gentamicin, gentamicin with enrofloxacin, and metronidazole with enrofloxacin showed 100%, 80%, and 60% efficacy in treating clinical cases in field trials, respectively. As a result, the study came to the conclusion the higher prevalence of endometritis-based S. aureus, genetic host shifts, narrow options for single drugs, and need for novel drug combinations to treat clinical cases.

Divergent Analyses of Genetic Relatedness and Evidence-Based Assessment of Therapeutics of Staphylococcus aureus from Semi-intensive Dairy Systems.

Use of antibiotics without following standard guidelines is routine practice in developing countries which is giving rise to genetic divergence and increased drug resistance. The current study analyzed genetic divergence and drug resistance by S. aureus and therapeutic efficacy of novel antibiotic combinations. The study revealed that 42.30% (minimum 20%-maximum 70%) of milk samples are positive for S. aureus. Study also revealed seven SNPs in the S. aureus nuc gene (c.53A>G, c.61A>G, c.73T>C, c.93C>A, c.217C>T, c.280T>C, and c.331T>A). Local isolates Staph-2 and Staph-3 were closely related to Bos taurus nuc gene (bovine S. aureus), while Staph-1 was closely related to Homo sapiens (human S. aureus) indicating shifting of host. Change of two amino acids and staphylococcal nuclease conserved domain was observed in all local isolates of S. aureus. The isoelectric points predicted by protParam of Staph-1, Staph-2, and Staph-3 proteins were 9.30, 9.20, and 9.20, respectively. The antibiotic susceptibility profile of S. aureus presented highest resistance against penicillin (46.67%) and glycopeptide (43.33%). When a single antibiotic regimen was adopted in a field trial, the highest efficacy was reported in the case of oxytetracycline (80%) while lowest was presented by azithromycin. Among antibiotics' combined regimen, the highest efficacy (80%) was presented by gentamicin with oxytetracycline: cefotaxime with vancomycin; and ciprofloxacin with vancomycin. The current study concluded rising percentages of S. aureus from dairy milk, proofs of genetic host shifts, and altered responses of in on field therapeutics.

Inhibition of miR-139-5p by topical JTXK gel promotes healing of Staphylococcus aureus-infected skin wounds.

BACKGROUND: The inflammatory skin wound response is regulated by argonaute 2-bound microRNAs (Ago2-miRNAs) such as miR-139-5p, which inhibit transcription of their target mRNAs. Jiang Tang Xiao Ke (JTXK) is a traditional Chinese medicine that reduces miR-139-5p expression, suggesting that topical application of JTXK may have effects on wound healing. METHODS: miR-139-/- mice and wild-type (WT) mice were employed to characterize the in vivo effects of miR-139-5p on sterile wound healing. Neutrophil migration and activation into the wound site were examined by live imaging analysis in lys-EGFP mice and myeloperoxidase/aminophenyl fluorescein assays, respectively. In silico and in vitro studies in differentiated HL60 cells were performed to identify miR-139-5p's downstream mediator(s). miR-139-/- neutrophil transplantation (with or without Eif4g2-knockdown rescue) or a topical JTXK gel preparation (with or without miR-139-5p mimic rescue) were employed to characterize the in vivo effects of miR-139-5p and JTXK, respectively, on Staphylococcus aureus (S. aureus)-infected wound healing. RESULTS: miR-139-/- mice display impaired sterile wound healing but improved S. aureus-infected wound healing. Eif4g2, a protein that supports neutrophil proliferation and differentiation, was identified as a key downstream mediator of miR-139-5p. miR-139-/- mice show elevated neutrophilic activation and Eif4g2 upregulation. miR-139-/- neutrophils enhanced S. aureus-infected wound healing in an Eif4g2-dependent manner. Moreover, topical JTXK gel therapy also enhanced S. aureus-infected wound healing in a miR-139-5p-dependent manner. CONCLUSIONS: miR-139-5p negatively regulates the neutrophilic response during S. aureus-infected wound healing, suggesting that JTXK or other miR-139-5p suppressants may be effective for treating infected skin wounds.

Pseudo-Bartter syndrome in Chinese children with cystic fibrosis: Clinical features and genotypic findings.

OBJECTIVES: To characterize the clinical and genotypic features of cystic fibrosis-associated pseudo-Bartter syndrome (CF-PBS) in Chinese children. METHODS: We recruited and characterized the clinical manifestations of 12 Chinese children with CF-PBS. Sweat test, blood and urinary analysis, sputum culture, chest and sinus computed tomography, and abdominal ultrasonography were obtained. Whole-exome sequencing, bioinformatics analysis, and Sanger sequencing validation were performed to define the genotypes. RESULTS: CF-PBS was accompanied by recurrent and/or persistent pneumonia (91.7%), pancreatitis (83.3%), vomiting and/or diarrhea (66.7%), failure to thrive and liver disease (58.3% respectively), among our patients. The predominant organisms found in the airways were Pseudomonas aeruginosa (83.3%) and Staphylococcus aureus (75.0%). The mean concentrations of blood gas and electrolytes were pH 7.58, bicarbonate 40.8 mmol/L, sodium 125.9 mmol/L, chloride 77.5 mmol/L, and potassium 2.6 mmol/L. A high recurrence rate (50.0%) of CF-PBS was observed despite continued electrolyte supplementation during follow-up. In all, 19 different variants of CFTR gene were identified, and 10 of these were found to be novel observations (c.262_266delTTATA[p.L88FfsX21], c.579+2insACAT, c.1210-3C>G, c.1733T>C[p.L578P], c.2236_2246delGAGGCGATACTinsAAAAATC[p.E746KfsX8], c.3068T>G [p.I1023R], c.3635delT[p.V1212AfsX16], c.3859delG[p.G1287EfsX2], c.3964-7A>G and ΔE23 [c.3718-?_3873+?del]). The c.2909G>A[p.G970D] was the most common variant, with an allele frequency of 16.6%. A homozygous genotype of c.1521_1523delCTT[p.F508del] was discovered for the first time in patients of Chinese origin. CONCLUSIONS: In China, CF-PBS usually presents early and recurs frequently in infancy, accompanied by multiple comorbidities. Recurrence of CF-PBS in school-going patients does occur but is rare. The p.G970D is the most frequent variant, with a significant ethnic tendency of Chinese origin.

Detection of heterogeneous vancomycin-intermediate Staphylococcus aureus: A preliminary report from south India.

Background & objectives: Although there are reports of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) across the globe, there is a lack of reliable data on hVISA in India. The present study was undertaken to determine the rate of hVISA among the methicillin-resistant Staphylococcus aureus (MRSA) isolates, and to compare the brain heart infusion agar with vancomycin 4 µg/ml (BHIV4) method with population analysis profile-area under the curve (PAP-AUC) method for the detection of hVISA and to study the distribution of mobile genetic element that carries methicillin-resistance gene SCCmec (Staphylococcal cassette chromosome mec) types among these isolates. Methods: BHIV4 and PAP-AUC methods were employed to detect hVISA among 500 clinical isolates of MRSA. SCCmec typing of these isolates was performed by multiplex polymerase chain reaction. The clinical presentation, treatment with vancomycin and outcome was documented for patients with hVISA. Results: The rate of hVISA was 12.4 per cent by PAP-AUC method. Sensitivity, specificity, PPV, NPV and kappa agreement of BHIV4 with PAP-AUC was 58.06, 93.15, 54.55, 94.01 per cent and 0.498, respectively. The isolation of hVISA was significantly (P<0.01) higher in patients admitted to intensive care units and wards than in patients attending the outpatient departments. Only 38 per cent of the patients received vancomycin as therapy. Majority of the hVISA isolates carried SCCmec type V or IV. Interpretation & conclusions: The rate of hVISA isolation in our study was 12.4 per cent. The sensitivity of the BHIV4 screening test was low, and was in moderate agreement with PAP-AUC test. SCCmec type V was the predominant type seen in half of the isolates. More studies need to be done in different parts of the country on a large number of isolates to confirm our findings.

Anti-inflammatory effects of Hederacoside-C on Staphylococcus aureus induced inflammation via TLRs and their downstream signal pathway in vivo and in vitro.

Acute lung inflammation is one among the top of infectious diseases. It is a pulmonary dysfunctional disease. It breaks the physiological coordination in the structures and functions of respiratory system. There are a few effective treatments to minimize the mortality of acute lung inflammation. It was induced by Staphylococcus aureus (S. aureus) via nasal instillation of mice. The common ivy (Hedera helix) is the most significant medicinal plant and considered as a traditional medicinal plant. The most active ingredient in the extract of ivy plant was Hederacoside-C (HDC). The purpose of this study was to investigate its anti-inflammatory effects on induced acute lung inflammation in vivo and (RAW 264.7 cells) in vitro and to elucidate its anti-inflammatory mechanisms. HDC was administered intraperitoneally 1 h after infection until 24 h. The dose was repeated every 8 h for three successful doses. Mice treated with HDC significantly reduced the pulmonary edema, white blood cells, wet-dry ratio (W/D) and myeloperoxidase (MPO) activity. HDC attenuated protein expression levels of MAPKs including p38, ERK, JNK and NF-κB including p65 and IκB-α pathways analyzed by ELISA. HDC also suppressed the protein expressions of TLR2 & TLR4 detected by Western blot. HDC also downregulated the gene expression of pro-inflammatory cytokines including IL-6, IL-1ß and TNF-α, but upregulated the gene expression of an anti-inflammatory cytokine IL-10 analyzed by qRT-PCR. In conclusion, our results stated that HDC could inhibit the S. aureus induced acute lung inflammation and it may be a potential therapeutic drug against acute lung inflammation.

Selenium influences mmu-miR-155 to inhibit inflammation in Staphylococcus aureus-induced mastitis in mice.

Mastitis, a major disease affecting dairy cows, is most commonly caused by Staphylococcus aureus (S. aureus). Selenium (Se) can activate pivotal proteins in immune responses and regulate the immune system, and microRNA-155 (miR-155) is a key transcriptional regulator for inflammation-related diseases. We constructed the model of mouse mastitis in vivo and primary mouse mammary epithelial cells (MMECs) in vitro, which were induced by S. aureus. Se content of the mammary was estimated using an atomic fluorescence spectrophotometer. Histopathological analysis was performed via hematoxylin and eosin (H&E) staining. The mmu-miR-155-5p mimic was transfected in MMECs, and viability was determined through the MTT assay. Transfected efficiency was evaluated by qPCR and fluorescence staining. Cytokines including TNF-α, IL-1ß, IL-10 and TLRs were detected with qPCR. In addition, western blotting was used to evaluate the expression of the NF-κB and MAPKs signaling pathways. The results demonstrated that a Se-supplemented diet improved the content of Se in mammary tissues. Histopathological studies indicated that the mammary glands were protected in the Se-supplemented group after S. aureus infection. Se-supplementation suppressed the production of MPO, mmu-miR-155, TNF-α, IL-1ß, and TLR2 and significantly inhibited the phosphorylation of NF-κB and MAPKs in vivo and in vitro. All the data indicated that mmu-miR-155 played a pro-inflammatory role in our study, and Se-supplementation could suppress the expression of mmu-miR-155 to inhibit inflammation in S. aureus-induced mastitis in mice.

Lysozyme-Assisted Photothermal Eradication of Methicillin-Resistant Staphylococcus aureus Infection and Accelerated Tissue Repair with Natural Melanosome Nanostructures.

Patients often face the challenge of antibiotic-resistant bacterial infections and lengthy tissue reconstruction after surgery. Herein, human hair-melanosome derivatives (HHMs), comprising keratins and melanins, are developed using a simple "low-temperature alkali heat" method for potentially personalized therapy. The mulberry-shaped HHMs have an average width of ∼270 nm and an average length of ∼700 nm, and the negatively charged HHMs can absorb positively charged Lysozyme (Lyso) to form the HHMs-Lyso composites through electrostatic interaction. These naturally derived biodegradable nanostructures act as exogenous killers to eliminate methicillin-resistant Staphylococcus aureus (MRSA) infection with a high antibacterial efficacy (97.19 ± 2.39%) by synergistic action of photothermy and "Lyso-assisted anti-infection" in vivo. Additionally, HHMs also serve as endogenous regulators of collagen alpha chain proteins through the "protein digestion and absorption" signaling pathway to promote tissue reconstruction, which was confirmed by quantitative proteomic analysis in vivo. Notably, the 13 upregulated collagen alpha chain proteins in the extracellular matrix (ECM) after HHMs treatment demonstrated that keratin from HHMs in collagen-dependent regulatory processes serves as a notable contributor to augmented wound closure. The current paradigm of natural material-tissue interaction regulates the cell-ECM interaction by targeting cell signaling pathways to accelerate tissue repair. This work may provide insight into the protein-level pathways and the potential mechanisms involved in tissue repair.

Anti-inflammatory activity of ß-caryophyllene combined with docosahexaenoic acid in a model of sepsis induced by Staphylococcus aureus in mice.

BACKGROUND: Sepsis is a set of serious organic manifestations caused by an infection, whose progression culminates in exacerbated inflammation and oxidative stress, poor prognosis, and high hospital costs. Antioxidants used against sepsis have been evaluated, including essential oils such as ß-caryophyllene (BCP), and polyunsaturated fatty acids, such as docosahexaenoic acid (DHA). The aim of this study was to evaluate the anti-inflammatory activity of the association of these two compounds. RESULTS: Treatment with BCP-DHA, at a dose of 200 µL/animal, significantly inhibited the migration of neutrophils in a Cg-induced peritonitis model. After Staphylococcus aureus infection, in the groups treated with BCP-DHA there was a significant decrease in the total and differential count of leukocytes, increased expression of cytokines TNF-α and IFN-γ in treated groups, an increase of IL-4 and IL-5 in B/D and B/D + SA groups, and an augmentation of IL-6 and IL-12 groups in B/D + SA groups. Histological and bacterial analysis revealed lower neutrophil migration and lower bacterial load in the infected and treated groups. CONCLUSION: In general, the BCP-DHA association presented anti-inflammatory activity against two different models of acute inflammation and infection, showing promising potential as a therapeutic adjuvant in sepsis. © 2019 Society of Chemical Industry.

The YIN and YANG of lipoproteins in developing and preventing infectious arthritis by Staphylococcus aureus.

Rapid bone destruction often leads to permanent joint dysfunction in patients with septic arthritis, which is mainly caused by Staphylococcus aureus (S. aureus). Staphylococcal cell wall components are known to induce joint inflammation and bone destruction. Here, we show that a single intra-articular injection of S. aureus lipoproteins (Lpps) into mouse knee joints induced chronic destructive macroscopic arthritis through TLR2. Arthritis was characterized by rapid infiltration of neutrophils and monocytes. The arthritogenic effect was mediated mainly by macrophages/monocytes and partially via TNF-α but not by neutrophils. Surprisingly, a S. aureus mutant lacking Lpp diacylglyceryl transferase (lgt) caused more severe joint inflammation, which coincided with higher bacterial loads of the lgt mutant in local joints than those of its parental strain. Coinjection of pathogenic S. aureus LS-1 with staphylococcal Lpps into mouse knee joints caused improved bacterial elimination and diminished bone erosion. The protective effect of the Lpps was mediated by their lipid moiety and was fully dependent on TLR2 and neutrophils. The blocking of CXCR2 on neutrophils resulted in total abrogation of the protective effect of the Lpps. Our data demonstrate that S. aureus Lpps elicit innate immune responses, resulting in a double-edged effect. On the one hand, staphylococcal Lpps boost septic arthritis. On the other hand, Lpps act as adjuvants and activate innate immunity, which could be useful for combating infections with multiple drug-resistant strains.

Effect and mechanism of citral against methicillin-resistant Staphylococcus aureus in vivo.

BACKGROUND: Citral is an active component of many plant extracts, and it is a safe additive used in food and cosmetics. A previous study showed that citral has a good antibacterial effect against methicillin-resistant Staphylococcus aureus (MRSA) in vitro, but its in vivo anti-infective activity has not been studied. Anti-MRSA activity and the preliminary mechanism of citral against MRSA were investigated in MRSA-infected KM mice. The ED50 was calculated using Karber's method. Groups were selected for inflammatory and oxidative stress level tests, and lung and liver tissues were counterstained with HE for detection of pathological changes. Cytokines and oxidative factors were evaluated using the ELISA method (one-way ANOVA computed using SPSS 19.0.). RESULTS: With the increase in the concentration of citral, the survival rate of MRSA-infected mice increased accordingly. The ED50 values of citral for intramuscular injection and intragastric administration were 0.09 and 0.26 g kg-1 respectively. Citral significantly reduced cytokines (IL-1ß, IL-6, TNF-α) and oxidative factors (malondialdehyde and hydroxyl radicals) of MRSA-infected mice, whereas it increased gluthtione and superoxide dismutase levels. Citral can reduce the lung inflammatory infiltrates infected by MRSA. CONCLUSIONS: Citral exerted a dose-dependent anti-MRSA effect and ameliorated MRSA-induced abnormal changes in inflammation and oxidative stress. This indicates that citral has the potential for development as a new anti-MRSA drug. © 2019 Society of Chemical Industry.

Effect of Selective Antibiotic Pressure on the MLS-B Phenotype in Methicillin-Resistant Staphylococcus aureus Strains Originating From Patients From Transplantation Wards: 24 Years of Observations.

INTRODUCTION: Staphylococcus aureus infection, and health care-associated-methicillin resistant S aureus (HA-MRSA) in particular, is a serious risk for patients treated with organ transplantation. The frequent combined resistance of these bacteria to macrolides, lincosamides, and streptogramin-B (MLS-B) limits the use of these drugs in therapy. AIM: Evaluation of the mechanism of MLS-B resistance among HA-MRSA strains derived from patients treated in surgical-transplantation wards, over a 24-year period, and assessment of correlation of clindamycin use and resistance phenotype. MATERIALS AND METHODS: One hundred and twelve HA-MRSA strains from patients in surgical-transplantation wards (clinical hospital, Warsaw), hospitalized in the period from 1991 to 2014. Methicillin-resistance was determined using phenotypic and genetic methods by detecting the mecA gene. Erythromycin/clindamycin resistance was determined by E-test, the iMLS-B (inductive) and cMLS-B (constitutive) phenotypes by the D-test method. The number of defined daily doses (DDD), statistically per 1000 person-days, was calculated in accordance with the WHO guidelines. RESULTS: Resistance to erythromycin/clindamycin in MRSA strains increased from 1991 to 2004-2007 from 64.7/11.8% to 100/76.9%, respectively. The frequency of the cMLS-B phenotype in the years 1991/2010-2011/2012 was 5.9%/76.9%/69.7%, respectively, and correlated with the increased use of clindamycin in the examined wards. In 2012, the percentage of MLS-B-sensitive isolates increased from 3.9 to 21.7%, while constitutive resistance decreased to 69.7%, which correlated with a decrease in the use of clindamycin. CONCLUSIONS: The proportion of cMLS-B to iMLS-B phenotypes in HA-MRSA is related to the amount of clindamycin used in hospital wards. Limiting the selection pressure of antibiotics can lead to complete loss of resistance or return to the inductive mechanism of its regulation.

Identification, ontogeny and expression analysis of a novel laboratory of genetics and physiology 2 (LGP2) transcript in Asian seabass, Lates calcarifer.

LGP2 (laboratory of genetics and physiology 2) is an important member of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), which plays a significant role in antiviral innate immunity. In this study, we have cloned the full-length cDNA sequence of LGP2 from Asian seabass, Lates calcarifer (AsLGP2). The complete AsLGP2 cDNA sequence consisted of 2586 nucleotides encoding a putative protein of 681 amino acids with a molecular mass of 77.6 kDa. From the AsLGP2 protein, four different conserved domains were predicted: a DExDc (DEAD/DEAH box helicase domain), a bacterial type III restriction enzyme domain (RES III), a HELICc (Helicase superfamily c-terminal domain and a RIG-I_C-RD (RIG-I C-terminal regulatory domain). The transcript of AsLGP2 could be detected in all the 11 tissues tested in healthy animals with high expression noticed in tissues facing external environment such as gill, hindgut and skin. The ontogenic expression profile of AsLGP2 implies a possible maternal transfer of this gene as it has been detected in all early embryonic developmental stages along with unfertilized eggs. Viral analogue, poly I:C, injection resulted in rapid up-regulated expression in different tissues with the highest modulation of expression observed in kidney followed by liver and gill. A rapid response of AsLGP2 expression was also observed in the different tissues of Vibrio alginolyticus-injected L. calcarifer, while significant change in expression was noticed following Staphylococcus aureus infection. Similarly, exposure to different pathogen-mimicking microbial analogues such as poly I:C, LPS and PGN resulted in enhanced expression of AsLGP2 in SISK cell-line. Taking together, these observations suggest that AsLGP2 can act as both antiviral and antibacterial cytosolic receptor and may play a significant role in embryonic and larval development in marine euryhaline teleosts like Asian seabass.

The evolution and functional characterization of miiuy croaker cytosolic gene LGP2 involved in immune response.

The laboratory of genetics and physiology 2 (LGP2) is a member of retinoic acid-inducible gene I (RIG-I)-like receptors (RLR receptors), which may participate in the immune regulation process. The role of LGP2 on modulating signaling was ambiguous, some researchers suggested that the regulation mechanism of LGP2 to melanoma differentiation-associated gene 5 (MDA5) and retinoic acid inducible gene-I (RIG-I) were different. In this study, the bioinformatics and functions of LGP2 from miiuy croaker (mmLGP2) were characterized. Comparative genomic analysis showed that the evolution of LGP2 in mammals was more conserved than it in fish. LGP2 contains three structural domains: ResIII, HelicaseC and RD, and ResIII structural domain of LGP2 was extremely conservative. The mmLGP2 was ubiquitously expressed in the tested miiuy croaker tissues and the expressions were significantly upregulated after stimulation with poly(I:C), indicating that LGP2 might participate in the immune response, especially antiviral immunity. Furthermore, immunofluorescence of miiuy croaker LGP2 presents in the cytoplasm in Hela cells. The overexpression of mmLGP2 can activate ISRE, but cannot activate NF-κB luciferase reporter, implying that mmLGP2 might act as a positive regulator in immune responses through activating ISRE to induce the expression of IFN. The research of mmLGP2 will enrich the information of fish LGP2, and the functional experiments will be helpful for the future research about fish immune systems.

Isorhamnetin Attenuates Staphylococcus aureus-Induced Lung Cell Injury by Inhibiting Alpha-Hemolysin Expression.

Staphylococcus aureus, like other gram-positive pathogens, has evolved a large repertoire of virulence factors as a powerful weapon to subvert the host immune system, among which alpha-hemolysin (Hla), a secreted pore-forming cytotoxin, plays a preeminent role. We observed a concentration-dependent reduction in Hla production by S. aureus in the presence of sub-inhibitory concentrations of isorhamnetin, a flavonoid from the fruits of Hippophae rhamnoides L., which has little antibacterial activity. We further evaluate the effect of isorhamnetin on the transcription of the Hla-encoding gene hla and RNAIII, an effector molecule in the agr system. Isorhamnetin significantly down-regulated RNAIII expression and subsequently inhibited hla transcription. In a co-culture of S. aureus and lung cells, topical isorhamnetin treatment protected against S. aureus-induced cell injury. Isorhamnetin may represent a leading compound for the development of anti-virulence drugs against S. aureus infections.

Decreased susceptibility to chlorhexidine and prevalence of disinfectant resistance genes among clinical isolates of Staphylococcus epidermidis.

Staphylococcus epidermidis is a versatile agent, being both a commensal and a nosocomial pathogen usually with an opportunistic role in association with implanted foreign body materials. Pre-operative antiseptic preparation is an important strategy for reducing the risk of complications such as surgical site infection (SSI). Currently, the most widely used antiseptics are alcohols, quaternary ammonium compounds (QACs), and the bisbiguanide chlorhexidine. Occurrence of resistance to the latter agent has drawn increasing attention. The aim of this study was to investigate if decreased susceptibility to chlorhexidine among S. epidermidis was present in our setting, a Swedish university hospital. Staphylococcus epidermidis (n = 143), retrospectively collected, were obtained from prosthetic joint infections (PJI) (n = 61), post-operative infections after cardiac surgery (n = 31), and the skin of the chest after routine disinfection prior to cardiac surgery (n = 27). In addition, 24 commensal isolates were included. Minimum inhibitory concentration (MIC) of chlorhexidine was determined on Mueller Hinton agar plates supplemented with serial dilutions of chlorhexidine. Five QAC resistance genes, qacA/B, smr, qacH, qacJ, and qacG, were detected using PCR. Decreased susceptibility to chlorhexidine was found in 54% of PJI isolates, 68% of cardiac isolates, 21% of commensal isolates, and 7% of skin isolates from cardiac patients, respectively. The qacA/B gene was present in 62/143 isolates (43%), smr in 8/143 (6%), and qacH in one isolate (0.7%). The qacA/B gene was found in 52% of PJI isolates, 61% of cardiac isolates, 25% of commensal isolates, and 19% of the skin isolates. In conclusion, decreased susceptibility to chlorhexidine, as well as QAC resistance genes, were prevalent among S. epidermidis isolates associated with deep SSIs.

Modulation of the norfloxacin resistance in Staphylococcus aureus by Cordia verbenaceae DC.

BACKGROUND & OBJECTIVES: Several chemical compounds isolated from natural sources have antibacterial activity and some enhance the antibacterial activity of antibiotics reversing the natural resistance of bacteria to certain antibiotics. In this study, the hexane and methanol extract of Cordia verbenaceae were assessed for antibacterial activity alone and combinated with norfloxacin against the Staphylococcus aureus strain SA1199B. METHODS: The minimum inhibitory concentration (MIC) of extracts was assayed using microdilution assay and the modulatory activity was evaluated using plate diffusion assay. RESULTS: The MIC observed varied between 256 to >1024 µg/ml. However, the antibiotic activity of norfloxacin was enhanced in the presence of subinhibitory concentrations of hexane extract of C. verbenaceae (HECV). INTERPRETATIONS & CONCLUSIONS: Our results indicate that Cordia verbenaceae DC. can be a source of plant derived products with antibiotic modifying activity.

Tannic acid inhibits Staphylococcus aureus surface colonization in an IsaA-dependent manner.

Staphylococcus aureus is a human commensal and pathogen that is capable of forming biofilms on a variety of host tissues and implanted medical devices. Biofilm-associated infections resist antimicrobial chemotherapy and attack from the host immune system, making these infections particularly difficult to treat. In order to gain insight into environmental conditions that influence S. aureus biofilm development, we screened a library of small molecules for the ability to inhibit S. aureus biofilm formation. This led to the finding that the polyphenolic compound tannic acid inhibits S. aureus biofilm formation in multiple biofilm models without inhibiting bacterial growth. We present evidence that tannic acid inhibits S. aureus biofilm formation via a mechanism dependent upon the putative transglycosylase IsaA. Tannic acid did not inhibit biofilm formation of an isaA mutant. Overexpression of wild-type IsaA inhibited biofilm formation, whereas overexpression of a catalytically dead IsaA had no effect. Tannin-containing drinks like tea have been found to reduce methicillin-resistant S. aureus nasal colonization. We found that black tea inhibited S. aureus biofilm development and that an isaA mutant resisted this inhibition. Antibiofilm activity was eliminated from tea when milk was added to precipitate the tannic acid. Finally, we developed a rodent model for S. aureus throat colonization and found that tea consumption reduced S. aureus throat colonization via an isaA-dependent mechanism. These findings provide insight into a molecular mechanism by which commonly consumed polyphenolic compounds, such as tannins, influence S. aureus surface colonization.

Enhancement of cutaneous immune response to bacterial infection after low-level light therapy with 1072 nm infrared light: a preliminary study.

We investigated the photobiomodulation effects of 1072 nm infrared light on the natural immune response involved in anti-bacterial and wound healing processes. Thirty mice infected with MRSA on the skin were divided into two groups. The experimental group was treated with 1072 nm infrared light (irradiance: 20 mW/cm(2), fluence: 12 J/cm(2) for 10 min) at 2, 4, 8, 12, 24 h, 3 and 5 days after inoculation and the control group with sham light. Serial changes of the mRNA levels of TLR2, IL-1ß, TNF-α, IL-6, iNOS, MCP-1, TGF-ß, bFGF and VEGF were studied by real time RT-PCR and those of the expression level of VEGF, bFGF, TGF-ß and NF-κB by immunohistochemistry. The mRNA levels of the cytokines involved in the early phase of anti-bacterial immune response (IL-1ß, TNF-α, IL-6, MCP-1) increased significantly in the 1072 nm group, peaking between 12 and 24 h post-inoculation. These levels normalized after 3-5 days. Immunohistochemistry revealed a notably stronger expression of VEGF in the 1072 nm group from 8-h post-inoculation to 5-day post-inoculation. We concluded that 1072 nm infrared light had a photobiomodulation effect which resulted in an enhanced biological immune response to the bacterial infection by MRSA and also increased the expression of VEGF to a significant level.