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PubMedDate not supplied

Antimicrobial susceptibilities of Staphylococcus aureus isolated from commercial broilers in northeastern Georgia.

Staphylococcus aureus is an important opportunist that can cause superficial to life-threatening illnesses in a variety of animal species. In poultry, this organism has been implicated in osteomyelitis, synovitis, and cellulitis. Whereas most infections can be treated with antibiotics, because of the organism's propensity to acquire antimicrobial resistance, it is important to continually monitor antibiotic susceptibilities of clinical isolates. We surveyed 77 clinical poultry S. aureus isolates, collected from 1998 to 2000, for susceptibilities to a panel of 18 antimicrobial agents. Thirty-six percent of isolates were susceptible to all antibiotics. Forty-three and 16% of avian S. aureus were resistant to one and two antibiotics respectively. Staphylococcus aureus isolates were commonly resistant to tetracycline (40%; minimal inhibitory concentration [MIC]90 > 32 microg/ml), lincomycin (19%; MIC90 > 32 microg/ml), erythromycin (12%; MIC90 > 8 microg/ml), and kanamycin (8%; MIC90 < 128 microg/ml). All S. aureus isolates were susceptible to chloramphenicol, gentamicin, streptomycin, nitrofurantion, linezolid, quinupristin/dalfopristin, vancomycin, and the production antimicrobials virginiamycin, salinomycin, and flavomycin. A periodic assessment of antimicrobial susceptibilities of important avian pathogens like S. aureus will be important in helping the clinician's choice of antibiotic to control infection.

Animals↗

PubMed1979

The development of mesosomes of Staphylococcus aureus during autolysis.

Mesosomes of Staphylococcus aureus were examined morphologically under the electron microscope. Three different methods of specimen preparation (thin section, freeze-fracture, and negative staining) were used to eliminate artifacts due to sample processing. Mesosomes were rarely seen in intact cells but were quite distinct in autolysed cells incubated in 1.2M sucrose -0.33M acetate buffer (pH 5.8) at 25 degrees C. The phospholipid content increased by 20% of the control as autolysis proceeded. Since the plasma membrane did not show any other significant changes, the development of mesosomes during autolysis was shown to be a real event. Most of the well-developed mesosomes were found at the septum in negatively stained specimens. Initial wall-lysis occurred at this site, suggesting a close relationship between autolysis and the development of mesosomes in S. aureus.

Bacteriolysis↗

PubMedDate not supplied

[Preflight Staphylococcus aureus carrier state of the cosmonauts].

A preflight study of Staphylococcus aureus carriage in cosmonauts has demonstrated that the microorganism harbors in 79.4% of the tested and microbial foci of the carriers amount to 10(2) ml. The isolated Staphylococcus aureus strains show a pronounced plasma coagulatory, alpha-toxic activity and 67.4% of them can be typed by the International set phages. Prophylactic administration of the native staphylococcal anatoxin increases specific antistaphylococcal immunity, reduces or eliminates completely Staphylococcus aureus in the upper respiratory airways.

Bacteriophage Typing↗

PubMed1999

A prospective survey of current methicillin-resistant Staphylococcus aureus control measures.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is now endemic in tertiary referral hospitals among the developed world. By prospective survey, the effect of two measures aimed to reduce the spread of MRSA was determined. First, a surgical ward with persistently high levels of MRSA detection was cleaned and renovated. Second, the medical records of all MRSA-colonized patients were electronically flagged, facilitating immediate application of control measures on readmission. METHODS: Data were collected for 995 newly colonized patients admitted between 1 July 1995 and 31 December 1997. Methicillin-resistant Staphylococcus aureus detection was determined before and after implementation of the interventions, along with the likely place of MRSA acquisition and the monthly incidence of MRSA detection for all inpatients. Chi-squared testing with odds ratios and 95% confidence intervals determined associations between the effect of control measures studied and MRSA detection rates. RESULTS: New MRSA detection was 21.6 per 1000 admissions before refurbishment compared with 20.4 per 1000 admissions to the surgical ward after refurbishment. New MRSA detection averaged 6.4 per 1000 hospital admissions before the introduction of record flagging and patient cohorting, compared with 6.2 per 1000 admissions after. CONCLUSION: Neither ward refurbishment, nor introduction of flagging, significantly reduced rates of colonization during the study period. In hospitals that receive MRSA-colonized patients and provide intensive care facilities, spread of MRSA is a major problem. Effective containment demands separate wards for MRSA-colonized and non-colonized patients. The need for such containment should be considered in design of the modern hospital.

Chi-Square Distribution↗

PubMed2000

A CD-1 mouse model of infection with Staphylococcus aureus: influence of gender on infection with MRSA and MSSA isolates.

Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscessation, toxemia, and other infectious diseases. An animal model using CD-1 mice was developed to study the pathogenesis of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). When inoculated into the CD-1 mouse model, it was shown that both MSSA isolates, (HR 78 and CSA-1) and MRSA isolates (MRSA 456 and MRSA 457) led to chronic infection of the kidney. Female CD-1 mice inoculated with MRSA 456 proved to be more susceptible to infection and mortality than their male counterparts. Castrated mice became more susceptible to infection than intact male mice, suggesting a hormonal involvement in the infection process.

Animals↗

PubMed1988

Study of Staphylococcus aureus teichoic acid immunodominant site by help of synthetic haptens.

The beta ribitol teichoic acid was extracted and purified from Staphylococcus aureus strain Wood 46 and chemically and immunologically characterised. Rabbit antiserum was prepared against formalin killed Staphylococcus aureus cells. Liquid phase immunoprecipitation of the beta ribitol teichoic acid-anti-Staphylococcus aureus serum system was studied by laser nephelometry. Various mono- and disaccharides (N-acetyl-glucosamine-ribitol with alpha- or beta-linkage and N-acetyl-glucosamine-ribitol-phosphate with beta-linkage) were prepared by organic synthesis, reproducing part of the ribitol teichoic acid molecule. Inhibition by those mono- or disaccharides of the precipitation of the beta-ribitol teichoic acid-Staphylococcus aureus antibodies system was studied quantitatively by determining inhibitory ratio of each inhibitor. Glucose, ribitol and glucosamine were weak inhibitors whereas N-acetyl-glucosamine was a better one, stronger than disaccharide with an alpha-linkage. The beta linked disaccharide and beta-methyl-N-acetyl-glucosamine gave comparable inhibition and both compounds were effective inhibitors. The most potent inhibitor was phosphorylated beta-linked disaccharide which inhibited 25% more than the same disaccharide without phosphorus. Thus, the function of phosphorus in Staphylococcus aureus beta ribitol teichoic acid recognition by antibodies was demonstrated.

Chromatography, Gas↗

PubMedDate not supplied

[Isolation of Staphylococcus aureus by the Baird Parker method from powdered milk].

There are many media recommended for the isolation of Staphylococcus aureus from foods, but only with some media one can obtain a good growth started with stressed cells. The Baird Parker (BP) medium is considered the best choice to recover stressed cells, however, it is not as good a medium to isolate Staphylococcus aureus from powder milk. Therefore, it is important to count with alternative media to enhance the chance for Staphylococcus aureus to grow from dehydrated products. Thirty-one powder milk samples contaminated with Staphylococcus aureus were analysed by Baird Parker method, employing four culture media: Baird Parker (BP), Baird Parker + tween + MgCl2 (BPTM), Pork plasma with bovine fibrinogen agar (PPF) and Salt Milk agar (SL). Staphylococcus aureus was isolated in SL, 38.7%; in BP, 3.2%; in BPTM, 6.4%; and PPF, 0%.

Agar↗

PubMed1999

Reduction in methicillin-resistant Staphylococcus aureus infection rate in a nursing home by aggressive containment strategies.

For the month of October, 1993, the Methicillin-Resistant Staphylococcus aureus nosocomial infection rate in our 42-bed Extended Care Unit/Nursing Home was 33% (8.5% for the 1993 year). Our facility was committed to decrease colonization and infection rates and to prevent the introduction of additional colonized patients into the closed environment. Methicillin-Resistant Staphylococcus aureus containment practices were instituted and consisted of total population and staff surveillance, aggressive containment measures and followed by maintenance containment protocols. The aggressive plan included contact isolation, baths with chlorhexagluconate, treatment of nasal carriers with mupiricin and treatment of both colonized and infected patients. This was followed by maintenance measures of screening new admissions for Methicillin-Resistant Staphylococcus aureus with contact isolation and treatment for positive as described during the aggressive phase. Total population surveillance was repeated after one year. Results showed that no employees were colonized with Methicillin-Resistant Staphylococcus aureus. The initial colonization rate in residents/patients was 52%. After one year the colonization rate dropped to 2% and the infection rate to 1.4%. Molecular epidemiology demonstrated that there was limited acquisition of new strains of Methicillin-Resistant Staphylococcus aureus within the Extended Care Unit. The process was shown to be cost effective. Aggressive containment practices applied to a nursing home with a high Methicillin-Resistant Staphylococcus aureus infection rate not only reduced rates of colonization, but also markedly reduced infections. This reduction was maintained over time.

Aged↗

PubMed1984

[Formation of differences in the electric potentials of the membrane vesicle in Staphylococcus aureus].

Membrane vesicles isolated from Staphylococcus aureus cells by ultrasonication possess the NADH-, succinate-, and malate oxidase activities, contain cytochromes a and b and have the lipid/protein ratio of 0.12-0.24. Energized membrane vesicles absorb permeant anions of tetraphenylborate and phenyldicarbaundecaborane. This results in the electric field generation with a "plus" sign on the inner side of the membranes. The generation of the membrane potential occurs in response to the addition of a respiratory substrate (NADH, malate, or succinate) and is inhibited by electron transfer inhibitors, such as rotenone, 2-N-nonyl-4-oxyquinoline-N-oxide, cyanide and the protonophore uncoupler, M-chlorinecarbonylcyanidephenylhydrazonium. The generation of the membrane potential takes place during ATP hydrolysis and in the course of the transhydrogenase reaction. The data obtained suggest the similarity of energization systems of St. aureus and those of animal mitochondria.

Adenosine Triphosphate↗

PubMed1987

[Toxic shock syndrome toxin-1 producing strains of Staphylococcus aureus in vaginal smears].

21 Staphylococcus aureus strains were isolated from 391 vaginal swabs. This corresponds to a frequency of 5.3%. In females using tampons this frequency was 7%, in users of napkins 2.4%. 2 out of these 21 S. aureus strains produced toxic shock syndrome toxin-1 (TSST-1). Both strains originated from women using tampons. Therefore, 5 out of 1000 women must be expected to carry TSST-1-producing S. aureus strains within their vagina.

Adolescent↗

PubMed1986

Epidemiology of antibiotic resistance in Staphylococcus aureus.

The genetic equipment of Staphylococcus aureus is at least as comprehensive as other organisms. Transposons provide the potential for reassortment of genes between plasmids and the chromosome. At least six different mechanisms of gene transfer between cells are documented in vitro. Phage-mediated conjugation is the transfer mechanism most likely to occur between staphylococci in nature. MRSA have evolved from a single clone and are now heterogeneous in properties. Some may show decreased virulence. The origin of new resistant determinants is likely to be other human cultures of Staph. aureus rather than an animal staphylococcal reservoir.

Anti-Bacterial Agents↗

PubMed2000

The rel gene is essential for in vitro growth of Staphylococcus aureus.

The stringent response in Staphylococcus aureus is mediated by the nucleotide guanosine pentaphosphate, whose synthesis is catalyzed by the product of the rel gene. We report here that the rel gene is essential for the in vitro growth of S. aureus, distinguishing it from all other bacteria tested for this requirement.

Genes, Bacterial↗

PubMed1998

Staphylococcus aureus prophylaxis in hemodialysis patients using central venous catheter: effect of mupirocin ointment.

Central venous catheterization is a common technique to establish rapid and temporary access for hemodialysis. However, it is a known risk factor for Staphylococcus aureus infection and bacteremia. Mupirocin is a topical antibiotic with high in vitro anti-staphylococcal activity. A randomized prospective trial was conducted to assess the effectiveness of mupirocin ointment in the prevention of Staphylococcus aureus skin and catheter colonization, and episodes of bacteremia in 136 end-stage renal disease patients. Of these, 67 received skin disinfection at the venous catheter insertion site with povidone iodine (control group), and 69 received the same treatment followed by application of 2% mupirocin ointment at the cannula site after catheter placement and at the end of each dialysis session. Patients were followed until catheter removal and were monitored for the development of Staphylococcus aureus skin/catheter colonization and episodes of bacteremia. Median duration of catheter use was greater in the mupirocin than in the control group (37 versus 20 d, P < 0.01). Patients in the mupirocin group had a significantly lower rate of Staphylococcus aureus isolation from the pericatheter skin (1.76 per 1000 versus 14.27 per 1000 patient-days, P < 0.001) and from the catheter surface (3.17 per 1000 versus 14.27 per 1000 patient-days, P < 0.001). The proportion of patients with Staphylococcus aureus skin infection at the insertion site was lower in the mupirocin group (4.3% versus 23.9%, P = 0.001). Staphylococcus aureus-associated bacteremia was observed in 17 patients (two in the mupirocin group [0.71 episodes per 1000 patient-days] and 15 in the control group [8.92 per 1000 patient-days], P < 0.001). The hazard ratio of developing Staphylococcus aureus bacteremia was 7.2 (95% confidence interval, 1.6 to 31.6) times greater in patients not receiving mupirocin. Mupirocin applied to the insertion site significantly reduces the risk of Staphylococcus aureus skin and catheter colonization, exit-site infection, and Staphylococcus aureus bacteremia in hemodialysis patients.

Adolescent↗

PubMed2004

Genetic characterization of methicillin-resistant Staphylococcus aureus.

The genome structure of Staphylococcus aureus is analyzed. The genome is composed of two domains. The first domain, descendent from an ancestral bacterial species, contains house-keeping genes that showed highest homology to those of Bacillus species. The second domain contained the genes responsible for virulence and drug-resistance in human infection that seems to have been acquired from other bacterial species via lateral gene transfer. The latter domain constitutes the genetic information that makes S. aureus a notorious hospital pathogen.

Biological Evolution↗

PubMedDate not supplied

Possible pseudoresistance of Streptococcus pneumoniae to penicillin G in a patient with a mixed pneumococcus-Staphylococcus aureus pneumonia.

We report the case of a 53-year-old woman with a mixed pneumococcus-staphylococcus pneumonia, in which both organisms were recovered from both sputum and blood. Streptococcus pneumoniae persisted in sputum 48 hours after initiation of high-dose intravenous penicillin G. When nafcillin was substituted for penicillin G, both pneumococci and staphylococci were eradicated from blood and sputum. This strain of Streptococcus pneumoniae was highly susceptible to penicillin G, but the associated strain of Staphylococcus aureus was not. The staphylococcus produced large amounts of a penicillin -degrading betalactamase . We reviewed the records of ten cases of pneumococcus pneumonia from the Wayne State University-Detroit Medical Center admitted from March 1978 to April 1981, in which sputum cultures were repeated within one to ten days after penicillin G had been initiated. At second cultures of sputum, Streptococcus pneumoniae was recovered in none of these latter cases. We further showed that on a blood agar culture plate in the presence of penicillin G, a beta-lactamase positive strain of Staphylococcus aureus allowed growth of Streptococcus pneumoniae. Therefore, despite penicillin therapy, Staphylococcus aureus in sputum may facilitate the persistence of Streptococcus pneumoniae.

Female↗

PubMed2002

The evolutionary history of methicillin-resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections that are becoming increasingly difficult to combat because of emerging resistance to all current antibiotic classes. The evolutionary origins of MRSA are poorly understood, no rational nomenclature exists, and there is no consensus on the number of major MRSA clones or the relatedness of clones described from different countries. We resolve all of these issues and provide a more thorough and precise analysis of the evolution of MRSA clones than has previously been possible. Using multilocus sequence typing and an algorithm, BURST, we analyzed an international collection of 912 MRSA and methicillin-susceptible S. aureus (MSSA) isolates. We identified 11 major MRSA clones within five groups of related genotypes. The putative ancestral genotype of each group and the most parsimonious patterns of descent of isolates from each ancestor were inferred by using BURST, which, together with analysis of the methicillin resistance genes, established the likely evolutionary origins of each major MRSA clone, the genotype of the original MRSA clone and its MSSA progenitor, and the extent of acquisition and horizontal movement of the methicillin resistance genes. Major MRSA clones have arisen repeatedly from successful epidemic MSSA strains, and isolates with decreased susceptibility to vancomycin, the antibiotic of last resort, are arising from some of these major MRSA clones, highlighting a depressing progression of increasing drug resistance within a small number of ecologically successful S. aureus genotypes.

Alleles↗

PubMed2006

LukM/LukF'-PV is the most active Staphylococcus aureus leukotoxin on bovine neutrophils.

Staphylococcus aureus is a ubiquitous pathogen causing infections in humans and domestic animals. It is often associated with bovine mastitis. Among secreted virulence factors, the leukotoxins constitute a family of toxins composed of two distinct subunits (class S and F proteins) which induce first Ca2+ influx and subsequent pore formation that allows ethidium entry. As mastitis-causing isolates harbor the genes of at least two, and often three leukotoxins, we compared the biological activities of the purified leukotoxins whose genes are found in mastitis-causing isolates on bovine polymorphonuclear neutrophils (PMN): spreading on a solid support, calcium influx and ethidium entry. In the spreading assay, the homologous pair LukM/LukF'-PV was the most active leukotoxin. Within each class, either S or F, subunits were interchangeable and generated leukotoxins with different specific activity. LukM was also very active when associated with heterologous F subunits. A similar ranking of homologous pairs was also found in the ethidium entry assay: LukM/LukF'-PV > HlgA/HlgB > HlgC/HlgB > LukE/LukD = LukEv/LukDv. In the Ca2+ flux assay, LukM/F'-PV was the most active pair, but gamma-hemolysin (Hlg) was also very efficient. LukEv/Dv was more active (twofold) than LukE/D in the spreading assay, but the two variants showed similar activities in the other two assays. Supposing that spreading and ethidium entry (pore formation) reflect toxic activities on bovine PMN, and Ca2+ influx cell activation, LukM/F'-PV was by far the most cytotoxic leukotoxin, but it was closely followed by gamma-hemolysin for PMN activation. These results suggest that LukM/F'-PV may constitute a particular virulence attribute of mastitis-causing S. aureus strains.

Animals↗

PubMed1999

Nasal carriage of methicillin resistant Staphylococcus aureus in a cardiovascular tertiary care centre and its detection by Lipovitellin Salt Mannitol Agar.

Ecological niches of Staphylococcus aureus are the anterior nares. Carriage of Staphylococcus aureus in the nose appears to play a key role in the epidemiology and pathogenesis of infection. Numerous studier have shown that elimination of nasal carriage using Mupirocin also eliminated hand carriage and the spread of infections in hospitals. Lipovitellin-Salt-Mannitol Agar was used for screening, isolation and presumptive identification of Staphylococcus aureus from nasal carriers. From November; 97 to August'98, 724 nasal swabs were cultured and 18.23% of health care workers were found to be nasal carriers of Staphylococcus aureus. Of these 12.15% were carriers of MRSA. The carrier rate was highest in December' 97 (32.07%). All MRSA carriers were treated with local application of Mupirocin for three days. A study of the antibiogram of the clinical isolates during the corresponding period showed 100% susceptibility of MRSA to Vancomycin. Susceptibility of MRSA to Clindamycin, Netilmycin, Rifampicin & Ofloxacin was 86.6%, 69.5%, 66% & 64.7% respectively.

Bacteriological Techniques↗