Observations on the indirect transmission of virulent ovine footrot in sheep yards and its spread in sheep on unimproved pasture

Virulent ovine footrot was transmitted accidentally to a group of 23 adult Merino sheep (flock B) after holding for 1 hour in sheep yards, which earlier the same day had contained another flock (flock A) with < 1% prevalence of sheep with footrot lesions. Sheep in flock B were rendered susceptible to virulent footrot by grazing 600 mm high unimproved pasture dominated by paspalum (Paspalum dilatatum) and kangaroo grass (Themeda australis) during warm, humid and wet weather. In addition to moisture, interdigital abrasions caused by the pasture might have predisposed the interdigital skin to infection with Dichelobacter nodosus.

Cutaneous pythiosis in the horse

Pythiosis of horses in an invasive, ulcerative, proliferative, pyogranulomatous disease of the skin and subcutis caused by Pythium insidiosum, a fungus-like oomycete in the order Peronosporales of the kingdom Protista. Pythiosis is a form of "phycomycosis," which is a complex of pyogranulomatous diseases that also includes conidiobolomysosis, basidiobolobysosis, and disorders caused by members of the order Mucorales.

Evaluation of a detergent scrub technique for the quantitative culture of Malassezia pachydermatis from canine skin

A detergent scrub technique using wash fluid consisting of 0.075 M phosphate-buffered saline, pH 7.9 containing 0.1 per cent Triton X-100 was evaluated for the quantitative culture of Malassezia pachydermatis from canine skin. Preliminary studies showed that the detergents Triton X-100, Tween 40 and Tween 80 were equally able to disperse suspensions of pure cultures of M pachydermatis, but that the yeast counts were significantly reduced (P < 0.001) after suspension in saline, Triton X-100 or Tween 40 for two hours. The counts in skin washings were also reduced (P < 0.001) after suspension for three hours in 0.1 and 0.05 per cent solutions of Triton X-100. Vortexing, or manual or mechanical shaking of the samples yielded comparable counts. The correlation between the counts on diseased skin measured by using detergent scrubs and a contact plate technique was highly significant (P < 0.001). The detergent scrub technique was suitable for the quantitation of M pachydermatis on canine skin provided that the samples were processed without delay.

Prospective comparison of two management strategies of central venous catheters in burn patients

OBJECTIVE

Central venous catheters (CVCs) are associated with sepsis in burn patients. This study was undertaken to compare two strategies of CVC management in patients with major burn injuries.

DESIGN

Forty-two burn patients with major burn injuries were randomly assigned to undergo site change every 48 hours of the CVC or to undergo wire guide exchange of the CVC every 48 hours at the same site.

MATERIALS AND METHODS

Catheter insertion site, distance from the burn wound, cultures of catheter tips, and blood cultures were obtained from all patients in a prospective manner.

MEASUREMENTS AND MAIN RESULTS

There was no difference in the incidence of CVC sepsis between the two groups studied. CVCs inserted less than 5 cm from the burn wound developed bacterial contamination at an earlier time than CVCs inserted more than 5 cm from the burn wound.

CONCLUSIONS

There was no advantage to changing the CVC insertion site every 48 hours. Changing the CVC using the wire guide technique did not prevent, nor predict, CVC bacterial contamination.

Comparison of two shampoos for treatment of Malassezia pachydermatis-associated seborrhoeic dermatitis in basset hounds

A randomised-double-blind parallel study compared the clinical and antimicrobial efficacies of a miconazole-chlorhexidine shampoo with a selenium sulphide shampoo for the treatment of seborrhoeic dermatitis associated with Malassezia pachydermatis in 33 basset hounds. All 16 miconazole-chlorhexidine treated hounds and 11 of 17 selenium sulphide treated hounds improved when shampooed at three-day intervals for three weeks. The miconazole-chlorhexidine treated hounds showed significantly greater reductions in pruritus (P < 0.01), erythema (P < 0.001), exudation (P < 0.01) and overall severity (P < 0.001), and in counts of M pachydermatis (P < 0.001), total bacteria (P < 0.001) and coagulase-positive staphylococci (P < 0.001), when compared to the selenium sulphide treated group. Improvements in scaling and coat condition did not vary significantly between the two groups. These results indicate that seborrhoeic dermatitis in basset hounds is often associated with elevated cutaneous populations of M pachydermatis and bacteria, and that the miconazole-chlorhexidine shampoo is more effective than the selenium sulphide product for the treatment for this disease.

Dermatophytosis in northern Greece during the decade 1981-1990

Dermatophytic infections are very common in Greece. In the Mycological Laboratory of the Venereal and Skin Diseases Hospital in Thessaloniki, 6572 isolates of different dermatophytes were obtained from 17,120 patients examined. It is suggested that 5% of the people who present with skin problems in Greece suffer from dermatophyte infections. They are frequent causative agents of tinea pedis, tinea cruris, tinea corporis, tinea capitis and tinea unguium. In this paper, the species, the number and the prevalence of the dermatophytes were studied according to location and sex of the patients. The contribution of dermatophyte infections to the overall incidence of superficial fungal infection over 10 years was also studied.

Clinical utility of LSR/A15 gene for Mycobacterium leprae detection in leprosy tissues using the polymerase chain reaction

Skin biopsy and slit-skin smears from 46 leprosy patients and 4 nonleprosy patients were tested for the presence of Mycobacterium leprae by the polymerase chain reaction (PCR) using primers based on the sequence of the LSR/15 kD gene. The PCR was found to be specific and sensitive, with a detection level of 10 and 100 bacilli. PCR using skin biopsies gave a higher detection rate than did slit-skin smears, probably due to the higher density of bacilli in a 4-mm punch biopsy. Dot blot hybridization with radioactive probes was 10-fold more sensitive than the ethidium bromide staining. Eight patients who did not show acid-fast bacilli in tissues by the conventional methods were shown to have PCR-amplified M. leprae DNA. False-negative results were obtained in 3 cases even though formal evidence for tissue inhibitors was absent.

Application of polymerase chain reaction for the detection of Mycobacterium leprae DNA in specimens from treated leprosy patients

In this study of leprosy patients apparently cured by dapsone monotherapy, the polymerase chain reaction (PCR), one of the most reliable and sensitive DNA-based assays, was used for the specific detection of Mycobacterium leprae DNA. Sputum and slit-skin samples from 44 such patients at Baba Baghi Leprosy Sanatorium in Iran were examined. Primers for a 530-base-pair fragment of the gene encoding the 36-kDa antigen of M. leprae were used for the study. The PCR results were compared with microscopy for acid-fast bacilli. Of the 44 sputum samples, 2 were positive by PCR (4.5%) and of the 44 slit-skin swabs taken from the same patients, 10 were PCR positive (22.7%). Only one patient was PCR positive for both sputum and slit-skin specimens (2.3%). No positive results were found by acid-fast microscopy. In total, 11 of 44 (25%) patients in this study were found to be PCR positive for M. leprae, and it was thought probable that this indicated the presence of live organisms. Particularly interesting was the statistically significant association of positive results from slit-skin swabs with paucibacillary rather than multibacillary leprosy. It is suggested that whereas relapse or immunological reaction in paucibacillary disease may result from surviving organisms, in multibacillary leprosy this may be due to re-infection.

Evidence that water transmits Vibrio vulnificus biotype 2 infections to eels

Vibrio vulnificus biotype 2 is classically considered an obligate eel pathogen. However, it has recently been associated with one human septicemic case. In this paper, the opportunistic behavior of this pathogen is discussed. The bacterium can survive alone in brackish water or attached to eel surfaces for at least 14 days. It is able to spread through water and infect healthy eels by using skin as a portal of entry. These results suggest that water and infected eels may act as reservoirs of infection. A capsule seems to be essential for waterborne infectivity, which would explain why cells recovered from naturally diseased eels give rise to pure cultures of opaque colonies. The spread of the disease is dependent on temperature and water salinity, thus suggesting a method to reduce the risk of epizootics and that of infection for humans.

Diagnosis of catheter-related infections: the role of surveillance and targeted quantitative skin cultures

The results of quantitative skin cultures have been proposed as predictors of central venous catheter infection. We prospectively observed 132 patients for 3 months after catheter insertion. Specimens were obtained from all patients for routine surveillance quantitative skin cultures. Targeted quantitative skin cultures and quantitative catheter cultures were done at the time of removal of the central venous catheter. At a positivity level of > or = 10(3) colony-forming units per 24-cm2 area of skin around the insertion site, the surveillance and targeted quantitative skin cultures had specificities and negative predictive values that exceeded 90%. However, they had sensitivities of 18% and 75%, respectively, and they had positive predictive values of 25% and 100%, respectively. Unlike surveillance quantitative skin cultures, targeted quantitative skin cultures that are done when catheter infection is suspected are highly sensitive, specific, and predictive.

Survival on skin and surfaces of epidemic and non-epidemic strains of enterobacteria from neonatal special care units

It has been suggested that increased ability to survive on the hands of hospital staff contributes to transmission of certain strains of Gram-negative bacteria. We tested this hypothesis by comparing the survival on fingertips, glass slides and membrane filters of epidemic (M, major) and matched non-epidemic (S, sporadic) faecal strains of Escherichia coli (n = 13 vs. 13) and Klebsiella spp. (n = 19 vs. 19) found among 1066 neonates in 25 special care units (SCUs). The time to 50% killing at 22 degrees C in air was longer for E. coli than for Klebsiella spp. both on human skin (median 6 vs. 2 min P < 0.001) and glass surfaces (15 vs. 8 min P < 0.001). On the other hand, Klebsiella spp. were superior to E. coli in long-term survival tests on membrane filters expressed as the minimum inoculum still yielding growth after 10 days exposure at 22 degrees C in air (10(5) vs. 10(8) bacteria P < 0.001). Despite a large variation in survival times between individual strains no differences between M strains and S strains were observed in any of the three tests. This indicates that bacterial properties other than survival on surfaces contribute to the increased capacity for transmission of certain strains of enterobacteria in SCUs.

Antibiotics in the preservation of allograft and xenograft skin

The application of antibiotics in the preservation of allograft and xenograft skin is controversial. The penicillin-streptomycin combination that is commonly used in reports in the literature was ineffective in our practice. Our Tissue Bank has tested different antibiotic combinations and found a more effective and suitable combination. After aseptic retrieval of pig and cadaver split skin, the skin strips were incubated in Eagle's MEM containing different antibiotic combinations. From frozen and fresh allogeneic and xenegeneic skin, 1-cm2 pieces were incubated in bacterial growth media, then tested. The antibiotic effect on skin samples of the highest antibiotic concentrations was assessed by growth inhibition around the skin discs. We followed up the clinical results after skin transplantation. The best results were obtained using the following antibiotic combination: 1000 mg/l ceftazidime, 1000 mg/l ampicillin and 80 mg/l amphotericin. The skin retained its antimicrobial effect after freezing and thawing. In 1992, 5 m2 cadaver and 50 m2 pig split skin were supplied to the Hungarian burn centres to cover deep partial and full skin thickness burned patients. There has not been a graft-originated infection during this period.

Management of small fragment wounds in war: current research

The majority of war wounds are caused by antipersonnel fragments from munitions such as mortars and bomblets. Modern munitions aim to incapacitate soldiers with multiple wounds from very small fragments of low available kinetic energy. Many of these fragments may be stopped by helmets and body armour and this has led to a predominance of multiple wounds to limbs in those casualties requiring surgery. The development of an appropriate management strategy for these multiple wounds requires knowledge of the contamination and extent of soft tissue injury; conservative management may be appropriate. The extent of skin and muscle damage associated with a small fragment wound, the way in which these wounds may progress without intervention and their colonisation by bacteria has been determined in an experimental animal model. Results from 12 animals are presented. There was a very small (approximately 1 mm) margin of nonviable skin around the entrance wound. The amount of devitalised muscle in the wound tract was a few hundred milligrams. Some muscles peripheral to the wound track also showed signs of damage 1 h after wounding, but this improved over 24 h; the proportion of fragmented muscle fibres in the tissue around the track decreased as time went on. There was no clinical sign or bacteriological evidence of the track becoming infected up to 24 h after wounding. This preliminary work suggests that, in the absence of infection, the amount of muscle damage caused by small fragment wounds begins to resolve in the first 24 h after injury, even without surgical intervention.

Lyme disease in the United Kingdom

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Tumour necrosis factor-alpha (TNF-alpha) synthesis is associated with the skin and peripheral nerve pathology of leprosy reversal reactions

Leprosy may be complicated by episodes of increased cell-mediated immunity towards Mycobacterium leprae (reversal reactions) which result in severe local immunopathology in skin lesions and peripheral nerves. Using in situ hybridization and MoAb techniques we have demonstrated TNF-alpha mRNA and TNF-alpha protein in macrophages infiltrating leprosy skin and peripheral nerve. Levels of TNF-alpha mRNA are significantly increased in reactional skin and nerve, particularly in borderline tuberculoid patients. TNF-alpha mRNA and TNF-alpha protein levels are higher in reactional nerves then reactional skin. In both reactional skin and nerve TNF-alpha mRNA is more abundant than TNF-alpha protein; this may reflect the rapid turnover of TNF-alpha protein in an immunologically dynamic situation, such as is seen in reversal reaction. Our findings emphasize the importance of documenting both mRNA and protein production when assessing the role of cytokines in pathology. The leprosy reversal reaction may be regarded as a useful model of tissue immunopathology in which TNF-alpha is generated as part of the host response to infection, but also produces local tissue damage.

Detection by PCR and analysis of the distribution of a fibronectin-binding protein gene (fbn) among staphylococcal isolates

The fibronectin-binding proteins of Staphylococcus aureus are considered to be important virulence factors for colonisation and infection. The polymerase chain reaction (PCR) was used to detect part of a gene equivalent to the fbnA gene of S. aureus in 120 isolates of staphylococci (S. aureus, S. epidermidis, S. haemolyticus, S. simulans, S. hominis, S. warneri, S. cohnii and S. lugdunensis). Primers specific for the binding domain region of the fbnA gene of S. aureus produced PCR products of the predicted sizes (93 and 207 bp). The identity of the PCR products was confirmed by digestion with DdeI and nucleic acid hybridisation. The fibronectin-binding activity of the staphylococci was determined with a particle agglutination assay (PAA). The fbn gene was found to be present by PCR in 107 of the 120 staphylococci tested, irrespective of their site of isolation, and expression of the gene was detected by PAA in 101 of the 120 strains.

Transfusion-transmitted bacterial infection

Transfusion-transmitted bacterial infection is a persistent but often underemphasized problem facing transfusion medicine today. The present status of bacterial contamination of red cells, platelet products and plasma, frequency of contamination, and types of organisms implicated is reviewed. Current methods of prevention and detection are discussed, as well as typical clinical presentations and therapy.

Antibiotic prophylaxis in dermatologic surgery

Antibiotic prophylaxis is generally administered either to prevent wound infection or to hinder the development of endocarditis. Although the use of antibiotics in certain circumstances to prevent wound infection can be straightforward, there are other circumstances in which the decision to use antibiotics is much less clear. Endocarditis prophylaxis has traditionally been based on the American Heart Association's guidelines, which do not cover dermatologic surgery. This article discusses the rationale and controversies surrounding the use of antibiotic prophylaxis for prevention of both wound infection and endocarditis, reviews the few studies that pertain to dermatology, and provides recommendations for antibiotic prophylaxis on a case-by-case basis for those who perform dermatologic surgery.

Comparison of blot-drying versus air-drying of povidone-iodine-cleansed skin

Povidone-iodine is the cleansing agent most commonly used before accessing implanted venous devices. This agent has peak bacteriocidal action when allowed to air-dry for 20 min postscrub. However, the drying time increases the length of the procedure and the risk for accidental contamination of the site. In this study, the effectiveness of air drying versus blot drying povidone-iodine-prepared skin sites was compared by examining the number of bacterial colonies present on skin cultures obtained after each drying method. No significant differences in the number of bacterial colonies between the two drying methods were found.

Cultivation of Borrelia burgdorferi from human tick bite sites: a guide to the risk of infection

BACKGROUND

The risk of acquiring Lyme disease has been evaluated by xenodiagnostic procedures with laboratory strains of Borrelia burgdorferi and laboratory-reared Ixodes ticks, or by clinical trials in which diagnosis was based on clinical findings, culture, or serologic tests.

OBJECTIVE

Our purpose was to determine the risk of infection from tick bites in a natural setting in which wild strains of B. burgdorferi were involved, by a biopsy culture technique.

METHODS

Skin biopsy specimens were obtained from Ixodes scapularis tick bite sites, processed, and examined for the presence of B. burgdorferi.

RESULTS

B. burgdorferi was cultivated from only 2 of 48 skin biopsy specimens. In both instances duration of tick attachment was approximately 24 hours.

CONCLUSION

In a hyperendemic region for Lyme disease the risk of infection after a deer tick bite appears to be low, particularly if the tick has been attached for less than 24 hours.