Antimicrobial drug resistance in Staphylococcus aureus isolated from cattle in Brazil

Isolates of Staphylococcus aureus obtained from apparently healthy cattle in the State of Paraiba, Brazil were characterized in relation to resistance to 21 antimicrobial agents. Among the 46 isolates obtained, resistance to penicillin was most frequent, followed by resistance to cadmium, streptomycin, arsenate, tetracycline, mercury, erythromycin and kanamycin/neomycin. All isolates were susceptible to fusidic acid, ethidium bromide, cetrimide, chloramphenicol, benzalkonium chloride, doxycycline, gentamicin, methicillin, minocycline, novobiocin, rifamycin, tylosin and vancomycin. Only six isolates were susceptible to all the drugs tested. With respect to the antibiotics, multi-resistant isolates were uncommon. These results are probably a consequence of the peculiarities of local drug usage pressures. In relation to metal ions, resistance to mercury was rare while resistance to arsenate was relatively frequent, which contrasts with the situation for human Staph. aureus strains. After treatment with ethidium bromide, elimination of resistance to penicillin, tetracycline, streptomycin, erythromycin and cadmium was observed, which was consistent with the genetic determinants being plasmid-borne.     

Staphylococcal strains involved in bovine mastitis are inhibited by Staphylococcus aureus antimicrobial peptides

The inhibitory activity of five bacteriocin (Bac)-producer strains of Staphylococcus aureus was tested against bacteria pathogenic for cattle. Sixty-five epidemiologically unrelated strains of Staph. aureus involved in bovine mastitis were used as indicators in an agar diffusion test. Bacteriocins produced by four strains could inhibit only a limited number of test organisms. However, all 65 indicator strains proved to be susceptible to the combined action of both bacteriocins encoded by pRJ9, a Bac plasmid found in strain A53. Therefore, the bacteriocins produced by this strain may represent new antimicrobial peptides with potential applications in the prevention and treatment of bovine mastitis.     

Epidemiology of toxic shock syndrome toxin-1 production in Staphylococcus aureus strains isolated in Denmark between 1959 and 1990

A total of 436 Staphylococcus aureus bacteremia strains isolated between 1959 and 1990 were tested for the production of toxic shock syndrome toxin-1 (TSST-1) by a semiquantitative reversed passive latex agglutination test. TSST-1 production was found in 147/260 (57%) of phage group I strains, excluding the "80" complex, and in 17/176 (10%) of non-group I strains. Strains of the 52, 52A, 80, 81 complex ("80" complex), constituting a subgroup of group I, did not have the same high frequency of TSST-1 production as the rest of group I strains (4% versus 57%). The "80" complex has almost disappeared in Denmark. TSST-1 production was found with the same high frequency among group I strains from the beginning (1959) and throughout the observation period. The TSST-1 production was associated with the phages 29 and/or 52, which in turn lysed 95% of group I strains. The TSST-1 production was quantitatively greater in the phage group I strains than in the non-group I strains. TSST-1 production of the bacteremia strains was not correlated to the clinical parameters: mortality, age, gender, bacterial focus, underlying diseases, or whether the infection was hospital or community acquired.     

Persistence in bovine mastitis of Staphylococcus aureus clones as assessed by random amplified polymorphic DNA analysis, ribotyping and biotyping

The physiological properties of joint capsule mechanoreceptors in the ankle joint of the chicken were studied in the 3-h period immediately after intra-articular injection of microcrystal sodium urate. The electrical activity was recorded from single C- and A-delta sensory fibres dissected from the parafibular nerve. C-fibres showed high levels of spontaneous activity and receptive fields that varied from single spots 1 mm in diameter up to 4 x 4 mm. Thresholds to mechanical stimulation ranged from 0.1 to 8 g and 80% of the units responded to movement of the joint. A-delta fibres showed little spontaneous activity and receptive fields that varied from 1 mm to 9 x 1 mm. Thresholds to mechanical stimulation ranged from 0.1 to 16 g and 17% responded to joint movement. A comparison of the physiological properties of the C- and A-delta fibres in sodium urate arthritis with similar fibres in normal and monoarthritic animals indicated an increased sensitivity in the C-fibres but not in the A-delta fibres. Sensitisation was observed in the significantly increased receptive field size, decreased response thresholds, increased response to joint movement and the high level of spontaneous activity. These changes in the sensitivity of the joint capsule C-fibre receptors provides peripheral neural evidence for the pain experienced in acute gouty arthritis.     

Antimicrobial substances produced by Staphylococcus aureus strains isolated from cattle in Brazil

Many studies have documented faster engraftment after transplantation with peripheral blood stem cells (PBSC) compared to bone marrow (BM) stem cells. Most comparisons, however, have been between unprimed BM and primed PBSC. We have collected engraftment data on 39 patients from 4 Danish centres and compared G-CSF primed BM with G-CSF primed PBSC in malignant lymphoma and solid tumours. In the lymphoma group 6 BM transplants were compared with 8 PBSC transplants, whereas in the testicular cancer group 16 BM transplants were compared with 9 PBSC transplants. In the lymphoma group, the time to platelet engraftment (platelets >20x10(9)/l unsupported) was median 15 d in PBSC transplants and median 34 d in BM transplants (p=0.003). In the solid tumour patients the difference in time to platelet engraftment was 11 and 18 d in PBSC and BM transplants, respectively (p<0.0001). In an attempt to explain this difference we performed CD34+ subset analysis of BM and PBSC. This analysis revealed a higher content of lineage restricted cells (CD34+CD61+ and CD34+GlyA+) in PBSC compared to BM. In conclusion, G-CSF mobilized PBSC seems to result in faster engraftment than G-CSF primed BM, which could be explained by an increased number of lineage specific progenitors in PBSC compared to BM.     

Inflammation in the bovine teat cistern induced by Staphylococcus aureus

The inflammatory response, characterized by the accumulation of leukocytes, bovine serum albumin and the lysosomal enzyme N-acetyl-beta-D-glucosaminidase, was studied after inoculation of either 5 x 10(5) colony-forming units (CFU) or 2 x 10(2) CFU of the Staphylococcus aureus strain SA 14391 into teat cisterns of dry cows after surgical closure of the passage between the teat and udder cisterns. Teat cistern samples were taken before, and twice daily for 7 days after, inoculation of the bacteria. Infusion of sterile saline constituted a control. Persistent infections occurred in all teats inoculated with the higher dose (5 x 10(5) CFU) of bacteria, and a prominent inflammatory response was elicited. Marked differences were observed in leukocyte migration patterns between different cows, and a cyclic influx of leukocytes was evident. Inoculation of the lower dose (2 x 10(2) CFU) of bacteria did not result in a persistent infection, and only a slight inflammatory response was observed. The results indicate that the bovine teat tissues are capable of mounting a strong local inflammatory response to S. aureus infection. A large number of leukocytes invaded the teat, but, despite their numbers, they were unable to subdue the infection, except when the bacterial count was low.     

Prevalence of Staphylococcus aureus among food handlers from a metropolitan university in Chile

BACKGROUND: An important agent of food intoxication is Staphylococcus aureus, that is able to produce enterotoxins. AIM: To detect Staphylococcus aureus contamination in cafeteria food handlers of a Chilean University. SUBJECTS AND METHODS: Nose, throat, hands and nail samples from 87 food handlers were obtained for microbiological examination. RESULTS: Fifty seven subjects (65.5%) were carriers of Staphylococcus aureus. Enterotoxigenic Staphylococcus aureus was found in 36 subjects (41%). The most frequently found enterotoxin was type B (18 samples) followed by type D (12 samples). Men bad a higher frequency of contamination than women (83 and 57% of positive samples respectively). CONCLUSIONS: The frequency of Staphylococcus aureus contamination among food handlers is high and should prompt personal and environmental hygienic measures.     

Capsular types and susceptibility to penicillin of pneumococci isolated from cerebrospinal fluid or blood in Denmark, 1983-1988

Subcutaneous apomorphine, administered by continuous waking-day infusion with boluses, or by repeated intermittent injection, was given to 71 parkinsonian patients with severe refractory levodopa related on-off fluctuations for 1-5 years. A mean reduction in daily off period time of approximately 50% was maintained, and the incidence of neuropsychiatric toxicity remained low on long-term follow-up. No clinically significant tolerance or loss of therapeutic effect was seen, although increasingly severe on-phase dyskinesias and postural instability marred the long-term therapeutic response in many patients. Despite these drawbacks, apomorphine, when combined with the peripheral dopamine receptor agonist domperidone, represents a significant therapeutic advance in the management of late-stage Parkinson's disease and should certainly be considered before experimental implantation procedures.     

Quinolone resistance mutations in the GrlB protein of Staphylococcus aureus

Two altered GrlB proteins (one with an Asp-432-->Asn alteration and one with an Asn-470-->Asp alteration) of Staphylococcus aureus were purified as fusion proteins to maltose-binding protein. The 50% inhibitory concentrations of levofloxacin were 14 and 3.4 microg/ml against topoisomerase IV containing GrlB proteins with alterations at positions 432 and 470, respectively. These results suggest that the alteration of Asp to Asn at position 432 may be responsible for quinolone resistance.     

Biofilm formation of Staphylococcus aureus strains isolated from impetigo and furuncle: role of fibrinogen and fibrin

Effective utilization of spiral computed tomography (CT) technology in imaging of the thorax requires an understanding of technical parameters that affect image and scan quality. This article discusses how operator-controlled scan parameters can be optimized to achieve diagnostic and cost-effective examinations appropriate for daily clinical practice.     

Relationship between thickness, chapping and Staphylococcus aureus colonization of bovine teat tissue

Post-milking measurements of teat skin chapping score, teat thickness and colonization by Staphylococcus aureus were determined for 11.5 d. Three teats on each of twelve Holstein cows, free from Staph. aureus intramammary infections, were immersed in 1 M-NaOH solution to induce teat chapping; the fourth teat served as a control. To achieve different degrees of chapping, one teat per cow received one immersion after each milking for three consecutive milking periods, a second teat received two immersions, and the third teat received one immersion which coincided with the last immersion of the other two teats. All teats were challenged twice with a skim milk broth culture of Staph. aureus (5 x 10(6) cfu) after the first and second milking following NaOH treatment. Measures were initiated with the milking following the last Staph. aureus challenges. Tissue thickness of the lateral side of the teat (barrel) and colonization by Staph. aureus declined with time. Thickness of the teat end varied more erratically. Teat skin chapping score was positively correlated (P < 0.001) with tissue thickness of the barrel and Staph. aureus colonization. Thickness of the barrel was not significantly correlated with Staph. aureus colonization. Barrel thickness as a covariate had a significant effect (P < 0.05) on teat skin colonization of Staph. aureus, whereas teat skin score and teat end thickness had no significant effect. Thus, thickness of the lateral side of the teat explained the greatest variation in Staph. aureus teat skin colonization in the model tested.     

Isolation of Mycoplasma and unstable L-forms from sporadic bovine mastitis

A case of giant cell aortitis causing ascending aortic aneurysm associated with aortic regurgitation is reported. The aneurysm was excised and the aortic valve replaced using a fresh homograft. The patient has been followed up for three and a half years. There is good evidence of correction of the haemodynamic lesion and no evidence of further arteritis or aneurysmal formation. The pathological and clinical problem of this disease are discussed.     

Identification of LytSR-regulated genes from Staphylococcus aureus

In this report, the characterization of a Staphylococcus aureus operon containing two LytSR-regulated genes, lrgA and lrgB, is described. Sequence and mutagenesis studies of these genes suggest that lrgA encodes a murein hydrolase exporter similar to bacteriophage holin proteins while lrgB may encode a protein having murein hydrolase activity.     

Production of exfoliative toxin A by Staphylococcus aureus isolated from mastitic cow's milk and farm bulk milk

The production of exfoliative toxins A and B (ETA and ETB) by Staphylococcus aureus isolated from mastitic cow's milk and farm bulk milk was examined by the reverse passive latex agglutination method (RPLA). ETA was detected in 2 (1.2%) of 162 isolates from mastitic cow's milk and in 1 (0.6%) of 166 isolates from farm bulk milk. RPLA titers of these isolates were much lower than in human isolates. No ETB was detected in any of the isolates tested. These ETA-positive isolates belonged to bovine ecovar. They were non-typable using the international phage set for human strains. When these ETA-positive isolates were subcutaneously inoculated into neonatal mice, general exfoliation of the epidermis accompanied by the so-called Nikolsky sign was not recognized. By the immunoblotting and PCR methods, however, ETA and eta gene were recognized in the ETA-positive isolates from mastitic cow's milk and farm bulk milk. These data suggest that ETA is also produced by bovine isolates of S. aureus, but in smaller quantities.     

Differential diagnosis of Staphylococcus aureus from Staphylococcus epidermidis and Staphylococcus saprophyticus by alphazurine A dye

Staphylococcal bacterial suspensions were streaked on Trypticase soy agar with 5% sheep blood culture plates. Paper discs containing alphazurine A, a triphenylmethane dye, were placed on the inoculated plates which were incubated at 37 degrees C for 24 hours. A wide zone of inhibition of growth of Staphylococcus aureus was present around the paper discs. Growth of Staphylococcus epidermidis and Staphylococcus saprophyticus was not inhibited.     

Drug resistance among malaria and other parasites

Recent decades have witnessed the emergence and spread of parasites resistant to standard drug therapies, particularly malaria. Chloroquine-resistant Plasmodium falciparum has now spread to most malarial areas, and resistance to other antimalarial drugs, including mefloquine and sulfadoxine-pyrimethamine, have become significant problems in some parts of Southeast Asia and South America. Chloroquine-resistant P. vivax is well established in Papua New Guinea and Indonesia and has been reported in other areas. Trichomonas and Giardia infections resistant to metronidazole have also been documented. This article reviews the current status of drug resistance among parasites, particularly malaria, and offers strategies for managing patients with these infections.     

Comparison of two regimens for the treatment of clinical bovine mastitis caused by bacteria sensitive to penicillin

The efficacies of two regimens for the treatment of acute clinical mastitis were compared in a randomised multi-centre field trial in Norway, using 657 cows. The purpose was to determine whether repeated intramuscular injections of penicillin G for three days were more effective than a single injection, when given in combination with intramammary treatment for five days. The results were evaluated on the basis of clinical and microbiological examinations and cell count determinations of quarter milk samples taken at the initial visit and four weeks later. There were no significant differences between the effects of the treatments, either for all the cows, or for subgroups of the cows based on age, stage of lactation, and systemic reaction, or the type of causal bacteria.