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Characterization of the fibrinogen-binding surface protein Fbl of Staphylococcus lugdunensis.

The fbl gene of Staphylococcus lugdunensis encodes a protein Fbl that is 58 % identical to the clumping factor A (ClfA) of Staphylococcus aureus. The fbl gene was present in eight clinical isolates of S. lugdunensis. When Fbl was expressed on the surface of Lactococcus lactis it promoted adherence to immobilized fibrinogen and cell clumping in a fibrinogen solution. Purified recombinant Fbl region A bound to immobilized fibrinogen in a dose-dependent manner and inhibited the adherence of both Fbl-expressing and ClfA-expressing strains of L. lactis to fibrinogen. Adherence of S. lugdunensis and L. lactis Fbl(+) to immobilized fibrinogen was also inhibited by rabbit anti-Fbl region A antibodies and rabbit anti-ClfA region A antibodies, as well as by human immunoglobulin with a high level of anti-ClfA antibodies. Alignment of the A domains of CflA and Fbl revealed that all of the ClfA residues implicated in binding to the gamma-chain of fibrinogen are conserved in Fbl. Nevertheless Fbl had a tenfold lower affinity for fibrinogen, suggesting that sequence differences that occur elsewhere in the protein, possibly in beta-strand E of domain N2, affect ligand binding.

Amino Acid Sequence↗

Identification and preliminary characterization of cell-wall-anchored proteins of Staphylococcus epidermidis.

Staphylococcus epidermidis is a ubiquitous human skin commensal that has emerged as a major cause of foreign-body infections. Eleven genes encoding putative cell-wall-anchored proteins were identified by computer analysis of the publicly available S. epidermidis unfinished genomic sequence. Four genes encode previously described proteins (Aap, Bhp, SdrF and SdrG), while the remaining seven have not been characterized. Analysis of primary sequences of the Staphylococcus epidermidis surface (Ses) proteins indicates that they have a structural organization similar to the previously described cell-wall-anchored proteins from S. aureus and other Gram-positive cocci. However, not all of the Ses proteins are direct homologues of the S. aureus proteins. Secondary and tertiary structure predictions suggest that most of the Ses proteins are composed of several contiguous subdomains, and that the majority of these predicted subdomains are folded into beta-rich structures. PCR analysis indicates that certain genes may be found more frequently in disease isolates compared to strains isolated from healthy skin. Patients recovering from S. epidermidis infections had higher antibody titres against some Ses proteins, implying that these proteins are expressed during human infection. Western blot analyses of early-logarithmic and late-stationary in vitro cultures suggest that different regulatory mechanisms control the expression of the Ses proteins.

Bacterial Proteins↗

Antimicrobial-resistant Staphylococcus aureus isolated from Australian wildlife admitted to a veterinary hospital.

Although antimicrobial resistance (AMR) is a growing One Health concern, little is known about AMR in Staphylococcus aureus from Australian wildlife. This study investigated the occurrence, phenotypic AMR profiles, and genetic characteristics of S. aureus from six representative Australian wildlife species admitted to a wildlife hospital in Western Australia, including the western grey kangaroo (Macropus fuliginosus), quenda (Isoodon fusciventer), pelican (Pelecanus conspicillatus), galah (Eolophus roseicapilla), shingleback skink (Tiliqua rugosa) and long-necked turtle (Chelodina colliei). Staphylococcus aureus was isolated from 11.7% (21/180, 95% CI: 7.4%-17.3%) of the animals on admission. Whole genome sequencing identified 13 multi-locus sequence types (STs) and various virulence factors, including the human-specific immune evasion cluster (IEC). Resistance to at least one antimicrobial class was observed in 63.6% of the isolates. The blaZ, erm(T), aac(6')-aph(2″), and tet(L) AMR genes were detected in 63.6%, 13.6%, 4.5%, and 4.5% of S. aureus, respectively. After 7 days of hospitalisation, S. aureus was isolated from 16.5% (16/97, 95% CI: 9.7%-25.4%) of the animals, including two methicillin-resistant S. aureus (MRSA) isolated from two pelicans. The two MRSA were identified as community-associated MRSA clones (mecA-positive ST1-IV and ST93-IV), suggesting direct or indirect transmission between humans and wildlife during hospitalisation may have occurred. This study highlighted Australian wildlife may be a potential reservoir for genetically diverse antimicrobial-resistant S. aureus. AMR surveillance including wildlife using a One Health approach may be required.

Animals↗

Clinical isolates of Staphylococcus aureus vary in ability to stimulate cytokine expression in human endothelial cells.

Human umbilical vein endothelial cells (HUVEC) were infected for 24 h with 18 well-characterized Staphylococcus aureus isolates, and the supernatants from infected HUVEC were analysed for interleukin (IL)-1beta, tumour necrosis factor-alpha, IL-6, IL-8, IL-10, IL-12p70, growth-related oncogene (GRO)-alpha, granulocyte macrophage colony-stimulating factor (GM-CSF) and regulated upon activation, normal T cell expressed and secreted (RANTES) by immunoassay. All staphylococcal isolates induced the expression of IL-6, IL-8, GRO-alpha, GM-CSF and RANTES. The magnitude of cytokine expression varied between isolates. Staphylococcus aureus inducing high expression of one of these cytokines also showed simultaneous high expression of the other four, indicating a common mechanism for the ability of individual S. aureus to induce expression of these cytokines. No direct correlation between cytokine expression and adhesion of S. aureus to HUVEC was observed, indicating that bacterial properties besides adhesion contribute to the activation of HUVEC.

Bacterial Adhesion↗

Staphylococcus aureus isolated from nostril anteriors and subungual spaces of the hand: comparative study of medical staff, patients, and normal controls.

An epidemiologic investigation of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (S. aureus) colonization was conducted at Kansai Medical University Hospital between 1990 and 1991. The incidence of nasal and subungual positivity for S. aureus was examined in a total of 156 subjects including inpatients, physicians, and nurses at a ward for dermatology, plastic surgery, and emergency patients, outpatients with atopic dermatitis and other skin diseases, and normal controls. Inpatients were most heavily colonized with MRSA (40.8%), but S. aureus colonization was most frequent in outpatients with atopic dermatitis (95.5%). Not only nostrils, which have been much discussed as a reservoir of S. aureus, but also subungual spaces seemed to be havens of S. aureus. Twelve out of 22 atopic dermatitis patients were positive for S. aureus on skin regions, and coagulase and phage testing showed a correlation between the nasal and skin-colonizing S. aureus. Coagulase type II and phase type NT (not typable) were the predominant types of S. aureus, including MRSA.

Dermatitis, Atopic↗

Low responsiveness of human neonatal lymphocytes to a B-cell mitogen, Staphylococcus aureus Cowan I (SpA CoI).

Responses of neonatal and adult lymphocytes to various mitogens were studied. Lymphocytes from umbilical cord blood (UCB) responded well to both phytohemagglutinin and concanavalin A, and also to pokeweed mitogen and Staphylococcus aureus Protein A. The responses of UCB lymphocytes to these mitogens were not significantly lower than those of adult peripheral blood lymphocytes (PBL). In contrast, UCB lymphocytes showed only a minimal response to killed Staphylococcus aureus Cowan I (SpA CoI), a potent B-cell mitogen for human PBL, although the proportion of B cells in UCB was not less than that in PBL. The low level of response of lymphocytes from UCB to SpA CoI was not ascribed to differences in dose response or kinetics. Purified B cells from UCB were not stimulated by SpA CoI either, suggesting tht the low responsiveness was not due to the suppressive effect of T cells or macrophages, but to some intrinsic defect in B cells in UCB. These results suggest that the B cells in neonates may be more immature than the T cells.

B-Lymphocytes↗

Analysis of borderline-resistant strains of methicillin-resistant Staphylococcus aureus using polymerase chain reaction.

Identification of methicillin-resistant Staphylococcus aureus by drug-susceptibility tests alone poses a serious problem, because a considerable number of clinical S. aureus isolates are borderline resistant to methicillin. To circumvent this problem, we have developed a quick and sensitive method of PCR amplification for the detection of mecA gene, which, coding for PBP2', is the specific genetic element of methicillin-resistant Staphylococcus aureus. This method made it possible to identify MRSA strains in a short time using as few as 30 cells as a starting material for template DNA. Using this method, we found that the strains of borderline methicillin-resistance could be accurately identified. We also found one S. aureus clinical strain, T3, which lacked mecA gene in spite of its resistance to methicillin.

Base Sequence↗

The role of MRSA (methicillin-resistant Staphylococcus aureus) adherence and colonization in the upper respiratory tract of geriatric patients in nosocomial pulmonary infections.

The mechanism of nosocomial respiratory infections caused by MRSA (methicillin-resistant Staphylococcus aureus) in geriatric patients was investigated. Seriously ill patients (SIP) undergoing naso-gastric tube feeding or intravenous hyperalimentation and moderately ill patients (MIP) who were orally fed, were examined for their colonization and infection by Staphylococcus aureus (S. aureus) in the respiratory tract. Colonization of MRSA in the upper respiratory tract in SIP was from six to ten times higher than that in MIP and was associated with a high incidence of MRSA pulmonary infections. In vitro S. aureus adherence to nasal or oropharyngeal cells demonstrated that bacteria binding to nasal cells was higher, which probably can be interpreted as an elevated occurrence of S. aureus colonization in the nasal cavity than in the throat. The binding activity of MRSA was not superior to that of MSSA (methicillin-sensitive S. aureus). Though MRSA binding to the nasal cells from SIP was not higher than those from MIP, MRSA colonization in the upper respiratory tract was more frequently seen in SIP (P < 0.01). A higher incidence of total infectious episodes (P < 0.02-0.001) and more frequent use of antibiotics (P < 0.02-0.001), which were potent against MSSA might be the basis for selection of MRSA in these patients. In fact, the rate of MRSA colonization on the skin (pressure sores) was also higher in SIP (P < 0.01). A low nutritional state in SIP (P < 0.01-0.02) might also be associated with MRSA colonization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

In vivo-like antigenic surface properties of Staphylococcus aureus from bovine mastitis induced upon growth in milk whey.

Antigenic surface properties of Staphylococcus aureus strains grown in milk whey were compared with TSB-grown bacteria using immuno-gold electron microscopy. It is shown that colloidal gold (CG) particles coated with polyclonal antibody raised against Staphylococcus aureus surface antigen expressed in vivo bound to the surface of S. aureus strain F1440 grown in milk whey, but not to homologous bacteria grown in TSB. S. aureus strains grown in milk whey agglutinated in the presence of the polyclonal antibody, whereas the corresponding bacteria grown in TSB did not agglutinate. Immuno-gold particles did not bind to milk whey-grown bacteria treated with periodate. Periodate-treated milk whey-grown bacteria did not agglutinate in the presence of the polyclonal antibody, whereas periodate treatment had no effect on TSB-grown bacteria.

Agglutination↗

Typing of Staphylococcus epidermidis colonizing in human nares by pulsed-field gel electrophoresis.

From the nares of 11 healthy adults, 253 strains of coagulase negative staphylococcus were isolated and 88% of them were identified as Staphylococcus epidermidis using the API STAPH system. Chromosomal DNA fingerprinting of the isolated strains revealed that each person carried multiple types of S. epidermidis in his or her nares. The colonization of the strains was not stable; the types of the isolates changed in the first and the second examinations 5 months apart. The results contrasted with previous findings in which only one strain of S. aureus colonized persistently in the nares of healthy adults.

Adult↗

The inhibitory effect of Staphylococcus epidermidis slime on the phagocytosis of murine peritoneal macrophages is interferon-independent.

The extracellular slime produced by Staphylococcus epidermidis has been shown to interfere with several human neutrophil functions in vitro, such as chemotaxis, degranulation and phagocytosis. Slime production has been suggested as a useful marker for clinically significant infections with coagulase-negative Staphylococcus. Since the main role of macrophages in defense mechanisms is phagocytosis, the effect of slime on the phagocytic activity of macrophages was investigated. The phagocytic activity of murine peritoneal macrophages treated with slime in vitro decreased in a dose-dependent fashion. A similar decrease was also observed in macrophages isolated from mice that had previously received intraperitoneal injection of slime. To investigate whether interferon also plays a role in this process, mice were treated with interferon or an interferon inducer, polyinosinic-polycytidylic acid (poly I:C), together with slime before macrophage isolation. The slime-suppressed phagocytic activity of macrophages was partially relieved by both agents, and the recovery effect of poly I:C in slime-suppressed phagocytosis of macrophages in vivo might be attributed to the increased interferon level in peritoneal fluid and sera. However, when slime was given to poly I:C-pretreated mice, the phagocytic activity remained suppressed. Thus, it appears that slime is able to suppress the phagocytic activity of macrophages regardless of the state of macrophage activation by poly I:C. The results suggest that the inhibition of phagocytosis by S. epidermidis slime may be independent from the activation of interferon.

Animals↗

Staphylococcus aureus requires increased level of Ca(2+) or Mn(2+) to grow normally in a high-NaCl/low-Mg(2+) medium.

Mg2+-availability in Staphylococcus aureus cells decreased significantly with increasing NaCl concentration in growth media. Cells grew in a NaCl-free, Chelex resin-treated complex medium only if the medium was supplemented with 50 microM MgCl2, while, growth was limited when the medium was further supplemented with 1.0 M NaCl. Cells grown in such a high-NaCl/low-Mg2+ medium exhibited the morphologic abnormality of larger than normal cells. Both sufficient growth and normal cell morphology were restored by increasing Mg2+ concentration in a high-NaCl medium, or by supplementation with either CaCl2 or MnSO4 in a high-NaCl/low-Mg2+ medium. Supplementing with BaCl2, SrCl2 or FeSO4, however, had no effect. These results indicate that Ca2+ and Mn2+ might play some essential role in the growth of Staphylococcus aureus in a high-NaCl/low-Mg2+ environment.

Barium↗

Skin colonization by Staphylococcus aureus in patients with eczema and atopic dermatitis and relevant combined topical therapy: a double-blind multicentre randomized controlled trial.

BACKGROUND: Staphylococcus aureus has a peculiar ability to colonize the skin of patients with eczema and atopic dermatitis (AD), and is consistently found in eczematous skin lesions in these patients. A correlation between the severity of the eczema and colonization with S. aureus has been demonstrated, and it has been determined that bacterial colonization is an important factor aggravating skin lesions. Patients colonized with S. aureus have been treated with antibiotics in several open and double-blind placebo-controlled studies, with conflicting results. OBJECTIVES: To investigate the colonizing features of S. aureus in the lesional and nonlesional skin of patients with eczema and AD in China and to compare the therapeutic effect of mupirocin plus hydrocortisone butyrate with vehicle ointment plus hydrocortisone butyrate. METHODS: A multicentre, double-blind randomized trial was conducted. Eczema Area and Severity Index (EASI) scores were evaluated before the start of the trial and on the 7th, 14th and 28th day of treatment. Swabs for bacterial isolation were taken from lesional skin before the start of the trial and on the 7th, 14th and 28th day of treatment, and from nonlesional skin only before the start of the trial. A combination topical therapy with mupirocin plus hydrocortisone butyrate ointment was used in the experimental group, with vehicle ointment plus hydrocortisone butyrate ointment as a control. RESULTS: Of 327 patients enrolled in the study, 208 had eczema and 119 had AD. Bacteria were isolated from 70.2% of lesional and 32.7% of nonlesional skin samples from patients with eczema, of which S. aureus accounted for 47.3% and 27.9%, respectively. Bacteria were isolated from 74.8% of lesional and 34.5% of nonlesional skin samples from patients with AD, of which S. aureus accounted for 79.8% and 80.5%, respectively. The colonization density of S. aureus was markedly higher in lesional than in nonlesional skin, both in patients with eczema and with AD (P < 0.01, P < 0.05), and was positively correlated with lesion severity. Considering the EASI scores before and after treatment and the final effective rate, good therapeutic effects were obtained in both the combination experimental groups and the control groups (P < 0.01), and there were no differences in the global therapeutic effect between the two groups in patients with eczema and with AD (P > 0.05). However, in patients with eczema with a clinical score of > 8 or in patients with AD with a clinical score of > 7, the therapeutic effect in the experimental groups was superior to that in the control groups (P < 0.05) on the 7th day of treatment. There were no differences between the two groups on the 14th and 28th days of treatment (P > 0.05). Following the improvement of symptoms and signs of eczema and AD, the positive rates of bacteria and S. aureus were reduced on the 7th day of treatment. CONCLUSIONS: This study confirmed that lesional skin of patients with eczema and AD was more frequently colonized with S. aureus than was nonlesional skin. The more severe the eczema, the higher the colonization rate of S. aureus, and S. aureus was also more often present in lesional and nonlesional skin in patients with AD than in those with eczema. Staphylococcus aureus infection is related to the pathogenesis of eczema and AD. An antibiotic-corticosteroid combination and corticosteroid alone both gave good therapeutic effect in eczema and in AD, and both reduced colonization by S. aureus. Early combined topical therapy is beneficial to patients with moderate to severe eczema and AD, and it is unnecessary to use antibiotics at later stages of disease or in mild eczema or AD.

Adolescent↗

The protective effect of some food ingredients on Staphylococcus aureus MF31.

The upper limiting temperature of growth of Staphylococcus aureus MF31 in heart infusion broth (HI) was about 44 degrees C but addition of monosodium glutamate (MSG) and soy sauce permitted the organism to grow above this temperature. This effect is similar to that of NaCl. Tomato ketchup, Worcestershire and HP sauces added to HI did not allow growth at the non-permissive temperature of 46 degrees C but death was delayed. Staphylococcus aureus died in unsupplemented chicken meat slurry at 46 degrees C but grew at 48 degrees C in slurry supplemented with 5.8% NaCl and survived incubation for 18 h at 50 degrees C in slurry supplemented with 5.8% NaCl and 5% MSG. Cultures grown at 37 degrees C had a D60 value of 2 min in 50 mmol/l Tris (pH 7.2) buffer. Cultures grown at 46 degrees C in HI containing 5.8% NaCl had a D60 value of 8 min in Tris buffer. Addition of 5.8% NaCl plus 5% MSG to the buffer increased the D60 by a factor of about 7 for both cultures. In storage experiments at room temperature, the culture grown at 37 degrees C and at 46 degrees C plus 5.8% NaCl died at about the same rate in salami. In milk powder, however, the count of 37 degrees C culture decreased from 10% g to 10(6)/g in 5 weeks while the count of 46 degrees C culture remained unchanged. In cottage cheese, freeze-dried rice and macaroni, the 37 degrees C cultures also died more rapidly. It is suggested that cultures grown at 46 degrees C plus 5.8% NaCl may be suitable for experiments with artificially contaminated foods.

Cheese↗

Plasmid profiles of Staphylococcus aureus causing bovine mastitis.

Plasmid profiles of Staphylococcus aureus, isolated from herds affected with chronic bovine mastitis, are heterogeneous, as shown by the study of 85 strains from 18 different farms. The strains isolated within a herd sometimes show related plasmid patterns, although even strains isolated from different quarters of the same udder may show variations in their plasmid content. Strains without antibiotic resistance are frequently free of plasmids. Therefore, the existence of mastitis Staph. aureus virulence plasmids is unlikely. Staphylococcus aureus, resistant to penicillin and streptomycin from 9 different farms show related plasmid patterns. This result confirms a geographic spread of certain mastitis Staph. aureus strains.

Animals↗

Behaviour of Staphylococcus aureus strains, producers of enterotoxins C1 or C2, during the manufacture and storage of Burgos cheese.

Burgos cheese was manufactured from pasteurized ewes' milk inoculated with Staphylococcus aureus strains FRI 137 and FRI 361, at levels of ca 10(3) and 10(5) cfu/ml and stored at 4 degrees, 10 degrees and 15 degrees C and at room temperature (10 degrees-15 degrees C). Populations of Staph. aureus and mesophilic aerobes, pH, and production of thermonuclease and enterotoxins C1 and C2 were investigated. Aerobic counts increased during cheese-making and storage. With both test strains, important growth was observed only during the storage period, the larger levels corresponding to the higher temperatures. Although Staph. aureus strains attained populations of over 10(8) cfu/g, no enterotoxin was detected. Strain FRI 361 reached 10(7) cfu/g without production of a detectable amount of thermonuclease. With strain FRI 137, the minimal population associated with enzyme activity was influenced by the inoculum size. Staphylococcus aureus counts are better indicators of staphylococcal growth in Burgos cheese than the thermonuclease test.

Aerobiosis↗

Polar lipids of Staphylococcus strains analysed by fast atom bombardment mass spectrometry.

This study used fast atom bombardment mass spectrometry (FAB MS) to obtain detailed information on polar lipids of Staphylococcus by examining 23 isolates. Eighteen major anions were found in the range m/z 199-297, consistent with the presence of carboxylate anions. A further 21 major anions were found in the higher mass regions of m/z 609-805, consistent with the presence of phospholipid anions. In Staph. aureus, Staph. epidermidis, Staph. haemolyticus and Staph. hominis, the most intense peaks putatively assigned as carboxylate ions were consistent with presence of C15:0, followed by C17:0 except in the case of Staph. epidermidis. The major phospholipid anions were consistent with the presence of PG(30:0), PG(32:0) and PG(33:0). It is concluded that Staphylococcus has a characteristic polar lipid profile and that qualitative and quantitative differences may be seen between Staph. aureus and Staph. epidermidis.

Carboxylic Acids↗

Inhibitory effects of sucrose monolaurate, alone and in combination with organic acids, on Listeria monocytogenes and Staphylococcus aureus.

The effects of sucrose esters of fatty acids, alone and in combination with ethylenediaminetetraacetic acid (EDTA), acetic acid, lactic acid and citric acid, on survival, growth and thermal inactivation of Listeria monocytogenes and Staphylococcus aureus were determined. The presence of sucrose monocaprate (400 micrograms ml-1) in tryptose phosphate broth (TPB) or tryptic soy broth (TSB) did not inhibit the growth of L. monocytogenes or Staph. aureus, respectively. However, significantly (P < or = 0.05) lower populations of L. monocytogenes were detected in TPB containing as little as 100 micrograms ml-1 sucrose monolaurate (SML) during the logarithmic growth phase compared to populations detected in TPB containing no SML. At 400 micrograms ml-1, SML was lethal to L. monocytogenes. Less marked inhibitory effects were observed with Staph. aureus. The addition of EDTA to broth containing SML had a synergistic effect on the inhibition of both organisms. The chelator alone had no effect at 100 micrograms ml-1 on either pathogen but was inhibitory at 200 micrograms ml-1. Inhibition of L. monocytogenes was more pronounced as the incubation temperature was decreased from 30 degrees C to 15 or 5 degrees C. The addition of 0.1% acetic or lactic acid to TPB minimized the inhibitory effect of 100 and 200 micrograms ml-1 SML during the first 32 h of incubation. Staphylococcus aureus behaved similarly, but not as dramatically, to L. monocytogenes when cultured in TSB supplemented with SML alone or SML and organic acids. A synergistic inhibitory effect of SML and EDTA on heat inactivation of L. monocytogenes was evident but the reverse phenomenon was observed with Staph. aureus. The effectiveness of SML in controlling the growth of L. monocytogenes and Staph. aureus in foods most likely to be contaminated with these pathogens should be further investigated.

Acetates↗