Analysis of meticillin-susceptible and meticillin-resistant biofilm-forming Staphylococcus aureus from catheter infections isolated in a large Italian hospital

Several characteristics were analysed in 37 Staphylococcus aureus isolates from nosocomial catheter infections: the PFGE profile after SmaI digestion of chromosomal DNA, the ability to form a biofilm on a polystyrene surface, antibiotic susceptibility patterns (penicillin, oxacillin, erythromycin, tetracycline, clindamycin, telithromycin, gentamicin, ciprofloxacin, quinupristin/dalfopristin, rifampicin, vancomycin and linezolid), and the presence of genetic determinants of antibiotic resistance and biofilm formation. All strains but three (92 %) were able to grow on a plastic surface as a biofilm. An almost complete association was found between phenotypes and genotypic traits of antibiotic resistance, whilst PFGE profiling showed the highly polyclonal composition of the set of strains under study. Sixteen isolates (43 %) were meticillin-resistant and were subjected to staphylococcal cassette chromosome mec (SCCmec) and cassette chromosome recombinase (ccr) complex type determination by multiplex PCR. Only a subgroup of six strains belonged to the archaic clone PFGE type and bore the SCCmec/ccrAB type I structure. Among the remaining strains some presented small rearrangements of the SCCmec/ccrAB genetic locus, whilst others could barely be traced back to a known structural type. These observations suggest that, at the local level and at a particular site of infection, S. aureus may show great genetic variability and escape the general rule of expansion of the S. aureus pandemic clones

Analysis of different genetics traits and their association with biofilm formation in Staphylococcus epidermidis isolates from central venous catheter infections

The aim of the present study was to characterize clinical isolates of Staphylococcus epidermidis, one of the bacterial species most often implicated in foreign-body-associated infections, for their ability to form biofilms and for the presence of mecA and IS256 element. Sixty-seven Staphylococcus epidermidis clinical isolates, obtained from implantable medical devices, were investigated. Overall, 70% of the strains were positive for ica operon genes, 85% possessed atlE, and 46% contained aap. In 89% of the population, the Congo red agar test confirmed the correlation between the presence of ica genes and slime expression. Almost all of the strains could be classified as biofilm producers by both the crystal violet assay and microscopy. The bacterial population studied showed a very high frequency of strains positive for mecA as well as for the IS256 element. Although well-structured biofilms have been previously observed only in those strains possessing genes belonging to the ica operon, this study demonstrates that strains lacking specific biofilm-formation determinants can be isolated from catheters and can form a biofilm in vitro. Hence, different and yet-to-be identified factors may work together in the formation and organization of complex staphylococcal microbial communities and sustain infections associated with implanted medical devices

Serum Levels and Urinary Excretion in Humans of BL-S 578 (Cefadroxil), a New Semisynthetic Cephalosporin

Single doses of 250 and 500 mg of BL-S 578 (cefadroxil), a new semisynthetic cephalosporin, were orally administered to 13 normal, healthy volunters and serum levels determined at timed intervals for 7 h. Peak concentration was obtained at 1 1/2 h after administration of 250 mg (8.981 μg/ml) or 500 mg (17.861 μg/ml). Urinary excretion levels within 24 h after ingestion of single doses of 250 and 500 mg of cefadroxil were 89.92 and 86.34%, respectively

A linear model for the pharmacokinetics of azithromycin in healthy volunteers

The pharmacokinetic profile of azithromycin, after oral ingestion of 500 mg, was determined in 10 healthy volunteers. Statistical and biochemical reason seemed to indicate a zero-order absorption of the drug. The disposition of azithromycin was described by a two-compartment model (plasma compartment and extravascular compartment) with elimination from the plasma compartment. The absorption process ends abruptly after a time T = 2.3 ± 0.49 h, from the administration. The transfer rate constant from the plasma compartment to the extravascular compartment (k12 = 0.12 ± 0.04 h-1) and the mean residence time of the drug in the extravascular compartment (MRT2 = 43.53 ± 13.80 h) indicate a rapid and extensive distribution of azithromycin from the serum into the extravascular fluids. The results confirmed the efficacy of a single daily dose of 500 mg per os for clinical use

Ceforanide: Human pharmacokinetics after I.V. injection

The pharmacokinetics of ceforanide, a new cephalosporin, were examined after intravenous injection of 250, 500 and 1000 mg of the drug to healthy human volunteers. The pharmacokinetic parameters show that ceforanide produces higher and longer-lasting serum concentrations than some other cephalosporins and that it is eliminated in the urine to a great extent. The serum and biological half-lives are fairly high. The pharmacokinetics of ceforanide are dose independent, and between slopes (β) of dose/time lines no significant differences exist, while significant differences between intercepts (B0) exist

Diversity of antibiotic resistance genes and staphylococcal cassette chromosome mec elements in faecal isolates of coagulase-negative staphylococci from Nigeria

Background Coagulase-negative staphylococci (CoNS) are opportunistic pathogens found as colonisers of the human gut. This study was carried out to examine the genetic resistance mechanisms in faecal isolates of CoNS. The study investigated 53 non-duplicate CoNS isolates obtained from the fresh stool samples of apparently healthy subjects in the community of Ile-Ife, South-Western Nigeria. Antibiotic susceptibility testing was assessed by the disc diffusion test while antibiotic resistance genes were analysed by PCR. mecA positive isolates were analysed by Staphylococcal Chromosome Cassette mec (SCCmec) and cassette chromosome recombinase (ccr) complex typing methods. Results Resistance genes were detected only in isolates that showed resistance by phenotypic screening. The aac(6′)–aph(2″) gene was detected in all the three isolates resistant to gentamicin. Four of the five erythromycin resistant isolates were positive for the ermC gene, the remaining isolate carried the msrA gene. The tetK gene was detected in 6 of the 7 tetracycline resistant isolates while 4 possessed the tetM gene. Three of the isolates (S. haemolyticus, S. xylosus and S. capitis) had both genes. Several SCCmec types were found: SCCmec I- ccrABβ2-α2 (4 isolates: 3 S. epidermidis, 1 S. warneri), SCCmecIVb- ccrABβ2-α3 (1 isolate: S. epidermidis), SCCmecIVd- ccrABβ2-α3 (8 isolates: 3 S. epidermidis, 2 S. xylosus, 1 S. saprophyticus, 1 S. warneri, 1 S. capitis), and untypable (2 isolates: S. epidermidis). Conclusion This genetic background could be a reservoir for interspecies gene transfer among CoNS and S. aureus in the intestinal tract

PCR M Typing: a New Method for Rapid Typing of Group A Streptococci

A new approach for the M-typing of Streptococcus pyogenes is reported. Oligonucleotide primers were used in a PCR to amplify the N-terminal region of the emm gene. The presence of the PCR amplification product is associated with the corresponding M serotype. This technique offers potential advantages over other molecular typing methods

Antibodies anti-HTLV III and lymphocyte subsets of high risk subjects.

208 assay for the research into anti-HTLV III antibodies and lymphocytes subsets were carried out on the same number of patients at risk. 11 homosexual man, 143 intravenous drug users (i.d.u.) and 3 children of drug addicts from hospitals in the Marche and Abruzzo and 51 haemophiliacs from hospital in Florence were examined. 3 determination of anti-HTLV III antibodies were taken from each subject using 3 different commercial Kits. The results concur with and confirm similar epidemiological studies that have been done. The haemophiliac group had the highest positive percentage (39.2%), then came i.d.u. (11.9%) and the homosexuals (10.0%). Furthermore, of the 38 positive totals, there were 22 with only one kit, 18 with two, and 15 with all three. The evaluation of the lymphocyte subsets did not strictly correlate with the presence of the antiretrovirus antibodies