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PubMed2001

[Mechanisms of methicillin and vancomycin resistance in Staphylococcus aureus].

The mechanism of methicillin and vancomycin resistance in Staphylococcus aureus (MRSA) is discussed, focusing on the phenotypic expression of resistance; i.e., pre-methicillin resistance, Egle-type resistance, heterogeneous and homogeneous resistance. Acquisition of staphylococcus cassette chromosome(SCCmec) by a recipient MSSA strain in the mecA-positive, and methicillin-susceptible status(pre-MRSA status) of S. aureus. Subsequent of the mecI-gene-mediated repression of mecA gene transcription results in the heterogeneous expression of methicillin resistance. It is only with the alternation of another chromosomal locus that the heterogeneous-to-homogeneous (hetero-to-homo) conversion of methicillin resistance occurs. Acquisition of a part of vancomycin-resistance(the level of hetero-VRSA) is associated with hetero-to-homo conversion of methicillin resistance, and full expression of vancomycin resistance(MIC = 8 mg/l) is achieved by additional acceleration of cell-wall synthesis causing apparent cell-wall thickening.

Methicillin Resistance↗

PubMed2001

Nasal carriage of methicillin-resistant Staphylococcus aureus among smokers and cigarette factory workers.

Effects of smoking and tobacco on nasal carriage and colonisation rates of Staphylococcus aureus were investigated on 368 healthy males aged between 30 and 40 years old. The study group comprised 100 non-smokers (control group), 91 smokers, and 177 cigarette factory workers (42 smokers, 135 non-smokers). Quantitative cultures were done from the nasal swabs of all participants. After identification and determination of colony counts, S. aureus strains were tested for methicillin resistance using the oxacillin disk diffusion method. The rates of nasal carriage of S. aureus were found to be 30% in the control group, 33% in smokers, and 41% in cigarette factory workers. Overall, S. aureus colonisation (> or = 500 cfu/ml) was detected in 72% of the carriers (55/76). Colonisation rates were 43%, 63%, and 85% in the carriers of the study groups, respectively. An increasing colonisation rate was detected in accordance with the increasing number of cigarettes smoked per day, and smoking period. While methicillin-resistant Staphylococcus aureus was only found in 3% of the 30 S. aureus strains isolated from the control group, its isolation rate was 20% in the 30 S. aureus isolates of the smokers, and 33% in the 72 S. aureus isolates of the cigarette factory workers. These results indicate that cigarette and/or tobacco appear to have noticeable effects on the ecology of the nose.

Adult↗

PubMed2001

[In vitro activity of linezolid against clinical isolates of methicillin-resistant Staphylococcus aureus].

In recent years, there has been a dramatic increase in the number of infections caused by multidrug-resistant Gram-positive microorganisms, making necessary the search for alternative antibacterial agents. Linezolid is a new synthetic antimicrobial agent with activity against multidrug-resistant Gram-positive cocci. The objective of this study was to determine the in vitro activity of linezolid against 74 clinical isolates of methicillin-resistant Staphylococcus aureus. Minimal inhibitory concentrations were determined by an agar dilution method following NCCLS criteria. Vancomycin, teicoplanin, rifampicin, trimethoprim-sulfamethoxazole and linezolid were studied at concentrations ranging from 128 to 0.008 mg/l. All of the isolates were susceptible to vancomycin, teicoplanin, and linezolid while four strains (5.4%) were resistant to rifampicin and five (6.7%) to trimethoprim-sulfamethoxazole. Linezolid showed excellent in vitro activity against 74 clinical isolates of methicillin-resistant Staphylococcus aureus with an MIC ranging from 0.25 to 2 mg/l

Acetamides↗

PubMed2001

Characterization of coagulase from Staphylococcus intermedius.

A protein coagulase was isolated from Staphylococcus intermedius 6131 using bovine prothrombin-Sepharose 4B and Bio-gel P-4 column chromatographies. Homogeneity was demonstrated by the formation of a single band in polyacrylamide gel electrophoresis and isoelectric focusing. The purified preparation possesses a molecular weight of 64,500, an isoelectric point of 4.1, consists of 615 total amino acid residues and demonstrates coagulase activity for human and rabbit fibrinogen, but does not show the activity for rat or guinea pig fibrinogens. This purified protein contains galactose and fucose, and the amino-terminal amino acid sequence was determined. The coagulase activity is inhibited by N-bromosuccinimide (NBS), suggesting that tryptophan is involved in this activity. The coagulase was heat stable to 80 degrees C and stable to pH over the range of 7-9. This is the first report of coagulase from Staphylococcus intermedius.

Animals↗

PubMed1979

Longitudinal study of circulating immune complexes in a patient with Staphylococcus albus-induced shunt nephritis.

The direct measurement and partial characterization of circulating immune complexes has been performed in a longitudinal study of a patient with Staphylococcus albus-induced shunt nephritis. The high levels of immune complexes were associated with cryoglobulinaemia and hypocomplementaemia. The activation of complement was found to be via the classical pathway, but the functioning of the alternative pathway may have been impaired in vivo due to very low levels of C3. The host response to the infection was also characterized by the production of a marked macroglobulinaemia, high titres of rheumatoid factor and a typical acute phase increase in the C-reactive protein level. Immune complex levels were persistently elevated many months after the removal of the focus of the infection. A possible explanation for this surprising finding may lie in the nature of the antigens in the immune complexes. It was found that the immune complexes contained both antibodies to and antigens from Staphlococcus albus. In particular, glycerol teichoic acid and staphylococcal nuclease were identified as components of the immune complexes present during the acute phase. Glycerol teichoic acid was also identified in the immune complexes found later although other Staphylococcus albus antigens as yet unidentified were also present and persisted in the circulation for several months.

Adult↗

PubMedDate not supplied

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study.

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

Colony Count, Microbial↗

PubMed2001

Staphylococcus corneal virulence in a new topical model of infection.

PURPOSE: To develop a topical inoculation model of Staphylococcus aureus keratitis in which scarification, contact lenses, and spermidine are used to inhibit the host defenses and to investigate the role of alpha-toxin in this infection. METHODS: An alpha-toxin-positive parent strain (8325-4), its isogenic alpha-toxin-negative mutant (DU1090), and a genetically rescued form of the mutant (DU1090/pDU1212) were bound to rabbit-specific contact lenses, treated with spermidine (50 mM), and applied to scarified rabbit corneas. Eyes were treated topically with spermidine before and after lens application. Eyes were graded for disease by slit lamp examination (SLE) every 6 hours until 24 hours PI (PI), and erosion diameters were measured. Histopathologic changes and colony forming units (CFUs) of bacteria were determined. RESULTS: Spermidine treatment and inoculation of eyes with Staphylococcus on contact lenses resulted in significant increases in both CFUs per cornea (P = 0.0041) and SLE score (P or= 0.1959) multilog increase in CFUs over the inoculum at 24 hours PI. The alpha-toxin-producing strains, 8325-4 and DU1090/pDU1212, caused significantly more disease than the alpha-toxin-deficient mutant DU1090 at 24 hours PI (P <or= 0.0001). Histopathology revealed bacteria in scarified regions of the corneas and, for 8325-4 and DU1090/pDU1212, extensive epithelial sloughing and severe inflammation. CONCLUSIONS: A new topical model of infection has been developed, and alpha-toxin is an important virulence factor in this model.

Animals↗

PubMed2000

[Phenotypic and genotypic characteristics of methicillin-resistant Staphylococcus aureus isolated in Western Pomerania].

One hundred forty-nine Staphylococcus aureus strains were collected between 1994 and 1996 from ambulatory and hospitalized patients in Western Pomerania (north-western part of Poland). The bacteria were isolated from wounds, bronchial tree, bronchoalveolar lavage (BAL), sputum, throat swabs, nose swabs, eye swabs, blood, peritoneal fluid and urine. Resistance to methicillin was checked by disc diffusion test and confirmed using screening according to NCCLS standards. Growth strains was established with crystal violet staining. Furthermore, sensitivity to 17 other antibiotics was tested. Macrorestriction patterns of DNA was studied using the restriction enzyme Sma I and pulsed field gel electrophoresis system (BioRad). Almost all MRSA were identified as multidrug-resistant and all were sensitive to mupirocin, vancomycin and teicoplanin. Basing on Sma I PFGE patterns, 17 different genotypes were identified. The majority of MRSA belonged to Sma I type A (60 isolates) in which 9 closely related subtypes (A1 divided by A9) were identified. The most common was subtype A1 (37 strains), followed by A2 (12 strains), A3 (3), A4 (3), and A5 divided by A9 (each representing a single strain). The strains were ubiquitous and showed large variation as to phenotype. Eleven other MRSA with an identical Sma I PFGE patterns were classified as type B. These strains were predominantly present in material collected at the Department of Urology, Second State Clinical Hospital in Szczecin, First State Clinical Hospital and from outpatients. A typical feature of these strains was an identical resistogram. The remaining types and subtypes (C1, C2, D, E, F, G, and H) were represented by single MRSA strains (Tab. 1). The results indicate that MRSA strains of Staphylococcus aureus present in the region of Western Pomerania belong in general to two genotypes distinguished by Sma I PFGE as type A and B.

Drug Resistance, Multiple↗

PubMed2001

Comparative study of disintegrated cells influence of Staphylococcus aureus, Escherichia coli and Candida albicans on human and mouse immune mechanisms.

The study presents comparison of immunomodulatory effects of Staphylococcus aureus, Escherichia coli and Candida albicans disintegrated cells on selected immune mechanisms of human and mouse leukocytes. We measured their phagocytic activity, phagocytic index and microbicidal activity against Staphylococcus aureus, Escherichia coli and Candida albicans cells as well as peroxidase and lysozyme activities of human and mouse leukocytes. Our results revealed predominantly inhibitory effect of disintegrated microorganisms on nonspecific immune functions of human leukocytes, but mainly stimulatory effect on mouse leukocytes monitored immune functions.

Adjuvants, Immunologic↗

PubMedDate not supplied

Effect of preventing Staphylococcus aureus carriage on rates of peritoneal catheter-related staphylococcal infections. Literature synthesis.

OBJECTIVE: To determine whether specific preventive measures reduce the rate of peritoneal catheter-related infections and peritoneal catheter loss due to Staphylococcus aureus. DESIGN: Structured literature synthesis. METHODS: Relevant studies were identified by MEDLINE search, from personal files, and from the reference lists of retrieved articles. We analyzed English-language studies on treatment targeted at S. aureus, with at least 10 subjects and at least 3 months of follow-up, and data on staphylococcal peritoneal dialysis catheter infections. We excluded noncontrolled studies. Two investigators abstracted data using a structured form. RESULTS: We evaluated six studies with concurrent controls and eight studies with historical controls. In one randomized, placebo-controlled, blinded study, periodic nasal mupirocin ointment reduced the rate of staphylococcal exit-site infection from 0.42 to 0.12 episodes/patient-year (p = 0.006), but had no effect on the rates of staphylococcal tunnel infection, peritonitis, or catheter loss. In one randomized study without placebo control, periodic oral rifampin reduced the rate of staphylococcal exit-site infection from 0.65 to 0.22 epi/pt-yr (p = 0.011), but had no effect on the rate of staphylococcal peritonitis. In another nonblinded, randomized, controlled study, the use of either rifampin or mupirocin was associated with low rates of staphylococcal catheter infections and catheter loss. In one study with historical controls, the rate of staphylococcal exit-site infection and peritonitis was lower after oral rifampin prophylaxis. In seven other studies comparing nasal or exit-site mupirocin to historical controls, the rate of staphylococcal exit-site infection decreased from 0.17 to 0.05 epi/pt-yr, the rate of staphylococcal peritonitis decreased from 0.18 to 0.06 epi/pt-yr, and the rate of catheter loss decreased from 0.09 to 0.05 epi/pt-yr during the mupirocin period. CONCLUSION: The literature provides strong evidence that staphylococcal carriage prophylaxis using either oral rifampin or mupirocin ointment in the nares or exit site reduces significantly the rate of exit-site infection due to Staphylococcus aureus. Weaker evidence based on studies with historical controls suggests that rifampin or mupirocin prophylaxis also reduces the rate of staphylococcal peritonitis and peritoneal catheter loss. Studies with a stronger level of evidence are needed to verify this last point.

Antibiotic Prophylaxis↗

PubMed2001

[Staphylococcus aureus sepsis--still life threatening disease].

We report an analysis of clinical course of 18 patients presenting with Staphylococcus aureus sepsis. Community acquired infection was caused by Methicillin susceptible S. aureus (MSSA) in 11 patients. MSSA in 3 and Methicillin Resistant S. aureus strains (MRSA) in 4 patients, were the etiologic factor in 7 patients with nosocomial infection. From anamnestic data patients presented with: elevated body temperature--18/18, arthralgia and myalgia--9/18, headache--8/18, nausea--6/18, chills--2/18. Physical examination on admission revealed: meningismus--12/18, hepatomegaly--11/18, purulent and haemorrhagic skin lesions--7/18 and impaired neurological status (Glasgow Coma Scale < or = 12)--6/18. The mean APACHE III score, calculated from data collected at diagnosis of sepsis was 47 (7-114). Several complications had been observed: endocarditis--10, purulent meningitis--5, focal CNS lesions--5, pneumonia--8, pulmonary abscess--3, hydrothorax--1, abscesses of the spleen--5, renum--4, osteomyelitis--2. 11/18 patients required ICU treatment. Ventilator assistance of respiration was necessary in 7/18. Acute thrombocytopenia (< 100,000/ml) was diagnosed in 60%. In 5 patients suppurative meningitis had been diagnosed with a mean pleocytosis-837 (173-1898) microL. The results of treatment were satisfactory in 11 patients, 3 patients required further surgical treatment (2--cardiosurgery, 1--orthopedic surgery), 4 patients died. Infection caused by community acquired MSSA strains had been characterized by severe clinical course with increased incidence of endocarditis, organ failure and abscess forming. We conclude that Staphylococcus aureus sepsis is still a life-threatening disease, which should be treated at centers with immediate access to imaging techniques of CNS and circulatory system as well as intensive care and cardiosurgery. Community acquired S. aureus sepsis compared with nosocomial infection is characterized by more severe clinical course and higher mortality, despite of a great susceptibility to most antibiotics of causative S. aureus strains.

APACHE↗

PubMedDate not supplied

[ATPase activity of Neisseria gonorrhoeae and Staphylococcus aureus strains].

It has been established that membrane vesicles of gonococci possess ATPase activity within 0.05-0.14 mmol of ATP during 60 min per 1 mg of protein and for staphylococcus--within 0.07-0.19 mmol of ATP for 60 min per 1 mg of protein. The identity in all the kinetic parameters is observed for all the studied gonococcus strains: Na+ and Ca2+ ions inhibit ATPase activity within 12-19%; Mg2+ ions increase the ATPase activity 2-2.5 times. Dicyclohexylcarboimide, a specific ATPase inhibitor, suppresses ATPase activity by 50-70%. ATPase activity in the strains of bacteria containing antibiotic-resistant plasmids is established to increase 1.2-2.8 times for gonococcus and 1.2-2.7 for staphylococcus as compared to sensitive ones.

Adenosine Triphosphatases↗

PubMedDate not supplied

Staphylococcus aureus pneumonia in turkey poults with gross lesions resembling aspergillosis.

The present report describes a case of Staphylococcus (Staph.) aureus pneumonia in turkey poults. Initially, 3-day-old poults with a history of increased mortality were submitted for necropsy. The poults had severe bilateral consolidation of the lungs with miliary caseous nodules. The gross lesions in the lungs were highly suggestive of aspergillosis. The next day, postmortem examinations were performed on 60 dead poults at the farm, and all 60 had similar lung lesions. Histopathologic examination of affected lungs revealed severe subacute multifocal bronchopneumonia with intralesional bacteria. Tissue Gram stain of lung sections demonstrated gram-positive bacterial cocci. Gomori methenamine silver stain of the lungs failed to demonstrate fungal agents. The histologic distribution of the lesions suggested an aerogenous route of infection. Staphylococcus aureus was isolated in pure culture from affected lungs. Hatchery contamination was suspected because of the severity and early onset of the lesions. Bacterial monitoring at the hatchery demonstrated marked Staph. aureus contamination in two setters, a hatcher's air duct, and the poult room. Improved hatchery cleaning and disinfection prevented a reoccurrence of the problem.

Animals↗

PubMed2001

[A study on the resistance of Staphylococcus aureus and the mechanisms of its resistance to fluoroquinolone].

OBJECTIVE: To investigate the resistance of Staphylococcus aureus(SA) and the mechanisms of its resistance to fluoroquinolones (FQ). METHODS: The susceptibility of SA (200 strains) to 12 antibiotics was detected by disc diffusion, The minimal inhibitory concentrations (MICs) of 52 strains to three FQ were determined by agar dilution method. 52 strains resistant to ciprofloxacin (MIC> or =4 mg/L) were studied for the presence of point mutations in the gyrA gene and grlA gene by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method and for the expression of norA gene by reserpine reverse test respectively. RESULTS: 34% of the strains were resistant to oxacillin(methicillin resistant Staphylococcus aureus, MRSA) and other antimicrobials as well, but no vancomycin resistant strain was found. The resistance rate of MRSA to ciprofloxacin was 79.4% and cross-resistance existed. It was found that 42 strains (80.8%) had a mutation at gyrA codon 84 (TCA-->TTA or GCA). Mutations at grlA codon 80 (TCC-->TAC or TTC) and codon 84 (GAA-->AAA)were observed in 10 (19.2%) and 14 strains(26.9%) respectively.Strains containing mutations in gyrA or both gyrA and grlA gene showed a higher level of ciprofloxacin resistance than those with alternation in grlA gene but with wild type gyrA or non-gyrA mutants (P < 0.01). Decreased MICs to ciprofloxacin, norfloxacin and levofloxacin in reserpine reverse test indicated the presence of norA phenotype. CONCLUSIONS: It is clear that emergence of resistant SA strains will continue to be a problem, especially in MRSA which was resistant to most of the antibiotics. Fluoroquinolones are not the choice for MRSA now. The resistance to fluoroquinolones in clinical isolates of SA are due to the mutations of the gyrA and grlA gene encoding the target enzyme of fluoroquinolones and cell membrane resistance. Mutations of grlA gene may differ in different districts.

Anti-Infective Agents↗

PubMedDate not supplied

[Effect of chlorhexidine on Staphylococcus aureus hospital isolates under different environmental conditions].

Antiseptic agents are widely used in hospitals, being essential when prevention and control of nosocomial infections are required. It is necessary to consider several aspects that affect the biocide activity, since they have direct incidence in hospital hygiene, health and also in the nosocomial infection rate. Organisms belonging to Staphylococcus genus are involved in such infections and, digluconate of chlorhexidine is one of the most used antiseptic agents for human and animal health. The current study involved the evaluation of this biocide agent against 19 nosocomial isolates of Staphylococcus with and without organic substances and applying distilled water and water of 300 ppm hardness as dilution means. Results show that hard water was one of the factors that most highly affected the bactericidal activity of chlorhexidine. Moreover we found that it affected bactericidal activity more than the interference generated by organic substances. Our study proves that chlorhexidine is an effective antiseptic for these gram-positive microorganisms.

Abscess↗

PubMedDate not supplied

Effect of viral preinfection upon cell adherence in some staphylococcus strains from specific infections or carriers.

The adherence of bacteria to eukaryote cells has been largely investigated as an essential step in the occurrence of bacterial infection. Some clinical and epidemiological studies have revealed the frequent association of certain viral infections with bacterial infections originating in the same ecological niche. Therefore, we investigated the effect of the viral preinfection (ADV4) of some cultivated cells (HEp-2 and IC.SK-27) upon the adherence of staphylococcus to these cells. The analysis of cell adherence within the mentioned conditions, estimated by flow cytometry, allowed of the following conclusions: 1. bacterial adherence to cultivated and virally preinfected cells is augmented by the viral preinfection, and its value on a given cell substrate may characterize a bacterial strain; 2. bacterial adherence to the investigated cell substrates does not correlate with the origin of the tested staphylococcus strains (infections or carriers) and some cell lines can differentiate bacterial strains depending upon the ecological niche or inside it.

Adenoviridae↗

PubMed2002

[The change in sensitivity of methicillin-resistant Staphylococcus aureus to vancomycin].

OBJECTIVE: To determine the shift of susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) isolates to vancomycin in recent years. METHODS: Antimicrobial susceptibility was determined by disk diffusion test (K-B method). The t-test was used to compare the mean diameters of zone of inhibition. RESULTS: The clinical isolates of MRSA from 1994 to 2000 were 218, 187, 292, 237, 351, 886 and 652 in number respectively. The mean diameters (mm) of the inhibition zone of MRSA isolates each year were 19.9, 19.1, 18.6, 17.4, 18.4, 18.2 and 17.8. Comparison of the diameters of the inhibition zone of MRSA isolates (K-B method) showed that the mean diameter of the inhibition zone from the 652 MRSA isolates in 2000 was much less than that of the 218 MRSA isolates in 1994 and the difference was significant (P < 0.001). The resistant rates to chloramphenicol, ciprofloxacin, erythromycin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole were 44.0%, 73.7%, 89.1%, 65.7%, 61.0% and 67.0%. CONCLUSION: Our observation demonstrated that the susceptibility of MRSA to vancomycin gradually decreased from 1994 to 2000. It is important to monitor the antimicrobial susceptibility of Staphylococcus aureus to vancomycin.

Anti-Bacterial Agents↗

PubMed2002

Recurrent methicillin-resistant Staphylococcus aureus wound ulcer after clear-cornea cataract surgery.

PURPOSE: To present a case of recurrent, methicillin-resistant Staphylococcus aureus (MRSA) wound ulcer after clear-cornea cataract surgery. METHODS: Case report. RESULTS: An 82-year-old man underwent an uncomplicated phacoemulsification procedure with posterior-chamber intraocular lens (PCIOL) implantation. Two weeks after surgery, a corneal ulcer was present at the wound site. Corneal tissue sample cultures produced methicillin-resistant Staphylococcus aureus. The ulcer responded to high-dose vancomycin but recurred twice as vancomycin was tapered. Lamellar keratectomy with conjunctival flap was performed at 6 months after surgery, with no additional ulcer recurrence. CONCLUSIONS: Wound infection after clear-cornea cataract surgery occurs infrequently. Management of these infections, however, can provide challenging clinical decisions.

Aged↗