Nocardia infections in cats: a retrospective multi-institutional study of 17 cases.

OBJECTIVE: To record 17 cases of nocardiosis in cats from eastern Australia and to compare this series with cases previously reported. DESIGN: Retrospective/prospective study. RESULTS: Nocardia spp infections were diagnosed in 17 cats over 14 years from the three eastern states of Australia. There were no isolates from dogs during this period, but one isolate from a koala and two from dairy cows. The majority of cats presented with spreading lesions of the subcutis and skin associated with draining sinus tract(s). Early cutaneous lesions consisted of circumscribed abscesses. Infections spread at a variable rate, generally by extension to adjacent tissues. Lesions were generally located in regions subjected to cat bite or scratch injuries, including limbs, body wall, inguinal panniculus and nasal bridge. In some other cases, lesions were situated on distal extremities. The clinical course was variable, from chronic, indolent, initially localised infections to acute fulminating disease. Of the 17 cats, 14 were domestic crossbreds and three were purebreds. There was a preponderance of male cats (12 castrated, 1 entire young adult, 1 entire kitten). Nine of 17 cats were 10 years or older. Interestingly, the majority of infections were attributable to N nova. Immediate and/or predisposing causes could be identified in all cases, and included: renal transplantation [one cat]; chronic corticosteroid administration [three cats]; catabolic state following chylothorax surgery [one cat]; fight injuries [seven cats]; FIV infections [three of seven cats tested]. Of the 17 cats, three were apparently cured. Four were thought to be cured, but infection recurred after several months. Three cats responded partially but were euthanased, while another was improving when it died of unrelated complications. Two died despite treatment and two were euthanased without an attempt at therapy. For two cats there were either insufficient records or the patient was lost to follow up. CONCLUSION: Nocardiosis is a rare, serious disease. Currently it is more common in cats than dogs. Nocardial panniculitis may be clinically indistinguishable from the syndrome caused by rapidly growing mycobacteria. Although the prognosis is guarded, patients with localised infections caused by N nova often respond to appropriate therapy. If definitive treatment is delayed because of misdiagnosis, the disease tends to become chronic, extensive and refractory. Insufficient duration of therapy leads to disease recurrence.

Diagnosis and management of Staphylococcus aureus bacteraemia.

Staphylococcus aureus bacteraemia (SAB) is common. Around 8000 cases occur per year in Australia, of which 60% are hospital- or healthcare-associated. Risk factors for SAB include injectable drug use, haemodialysis, indwelling vascular catheters and immunosuppression. Metastatic infection develops in up to one-third of patients with SAB, with joints and heart valves being the most commonly affected sites. Community-acquisition,persistent fever, positive blood cultures after 48 h of treatment and the presence of embolic lesions correlate with the presence of complicated SAB (i.e. high risk of endocarditis and/or other metastatic complications). All patients require careful clinical evaluation to exclude endocarditis and other metastatic foci. Echocardiography,preferably transoesophageal echocardiography, should be performed to exclude endocarditis. Most patients with SAB, and all with features of complicated SAB, require prolonged intravenous antibiotic therapy (at least 4 weeks), but a subgroup with good prognostic features may be suitable for shorter intravenous therapy (2 weeks). Penicillinase-resistant penicillins (e.g.flucloxacillin) are the agents of choice for SAB with methicillin-sensitive strains. Vancomycin or first-generation cephalosporins are alternatives but have lower antimicrobial activity than flucloxacillin. However, vancomycin remains the therapy of choice for SAB due to methicillin-resistant strains. Combination therapy with gentamicin may be useful for the first few days of treatment in selected patients, but otherwise there are few data to support the use of combination regimens in SAB. Newer agents such as linezolid and quinupristin/dalfopristin may have a role in selected patients, especially in SAB due to S. aureus strains with reduced susceptibility to vancomycin.

PCR studies of feline leprosy cases.

16S rRNA gene sequence analysis provided evidence for two different mycobacterial species, Mycobacterium lepraemurium and a potentially novel species, as causative agents of 'feline leprosy'. Comparison of 16S rRNA gene sequence data obtained for M. lepraemurium and the potentially novel species indicated 12 nucleotide differences over a 446 bp region encompassing the V2 and V3 hypervariable regions. From available 16S rRNA gene sequence data, M. lepraemurium shared greatest nucleotide identity with M. avium subsp paratuberculosis and M. avium. The novel species had a long helix 18 in the V3 region and shared greatest nucleotide identity with M. leprae, M. haemophilum and M. malmoense. The novel species had an additional 'A' nucleotide at position 105 of the aligned 16S rRNA gene sequence, the only other mycobacterial database sequence having this same extra nucleotide being M. leprae. This nucleotide variation was exploited to develop specific PCR assays for the two species. These were found to be effective and specific when tested against a panel of mycobacteria including species found in feline leprosy lesions and closely related mycobacteria and also when applied directly to formalin-fixed, paraffin-embedded tissues from feline leprosy cases.

Feline leprosy: two different clinical syndromes.

Feline leprosy refers to a condition in which cats develop granulomas of the subcutis and skin in association with intracellular acid-fast bacilli that do not grow on routine laboratory media. In this study, the definition was extended to include cases not cultured, but in which the polymerase chain reaction (PCR) identified amplicons characteristic of mycobacteria. Tissue specimens from 13 such cases from eastern Australia were obtained between 1988 and 2000. This cohort of cats could be divided into two groups on the basis of the patients' age, histology of lesions, clinical course and the sequence of 16S rRNA PCR amplicons. One group consisted of four young cats (less than 4 years) which initially developed localised nodular disease affecting the limbs. Lesions progressed rapidly and sometimes ulcerated. Sparse to moderate numbers of acid-fast bacilli were identified using cytology and/or histology, typically in areas of caseous necrosis and surrounded by pyogranulomatous inflammation. Organisms did not stain with haematoxylin and ranged from 2 to 6 microm (usually 2 to 4 microm). Mycobacterium lepraemurium was diagnosed in two cases based on the sequence of a 446 bp fragment encompassing the V2 and V3 hypervariable regions of the 16S rRNA gene a different sequence was obtained from one additional case, while no PCR product could be obtained from the remaining case. The clinical course was considered aggressive, with a tendency towards local spread, recurrence following surgery and development of widespread lesions over several weeks. The cats resided in suburban or rural environments. A second group consisted of nine old cats (greater than 9 years) with generalised skin involvement, multibacillary histology and a slowly progressive clinical course. Seven cats initially had localised disease which subsequently became widespread, while two cats allegedly had generalised disease from the outset. Disease progression was protracted (compared to the first group of cats), typically taking months to years, and skin nodules did not ulcerate. Microscopically, lesions consisted of sheets of epithelioid cells containing large to enormous numbers of acid-fast bacilli 2 to 8 microm (mostly 4 to 6 microm) which stained also with haematoxylin. A single unique sequence spanning a 557 bp fragment of the 16S rRNA gene was identified in six of seven cases in which it was attempted. Formalin-fixed paraffin-embedded material was utilised by one laboratory, while fresh tissue was used in another. The same unique sequence was identified despite the use of different primers and PCR methodologies in the two laboratories. A very slow, pure growth of a mycobacteria species was observed on Lowenstein-Jensen medium (supplemented with iron) and semi-solid agar in one of three cases in which culture was attempted at a reference laboratory. Affected cats were domicile in rural or semi-rural environments. These infections could generally be cured using two or three of rifampicin (10-15 mg/kg once a day), clofazimine (25 to 50 mg once a day or 50 mg every other day) and clarithromycin (62.5 mg per cat every 12 h). These findings suggest that feline leprosy comprises two different clinical syndromes, one tending to occur in young cats and caused typically by M lepraemurium and another in old cats caused by a single novel mycobacterial species.

Bacteremia due to periodontal probing: a clinical and microbiological investigation.

BACKGROUND: Infective endocarditis can occur in susceptible individuals due to bacteremia of oral origin. The aim of this study was to investigate the occurrence of bacteremia caused by full mouth periodontal probing. METHODS: Forty patients, 20 with adult periodontitis (10 males, 10 females; mean age 43.0 years) and 20 with chronic gingivitis (11 males, 9 females; mean age 35.5 years) were investigated. Prior to and immediately following periodontal probing, 20 mL of venous blood were obtained from each patient and inoculated into aerobic and anaerobic blood culture bottles and incubated. Negative bottles were monitored continuously for 3 weeks before being discarded. Bottles which signalled positive were subcultured and isolates identified to genus level. Periodontal probing consisted of measuring pockets at 6 points around each tooth and recording the presence or absence of bleeding. A plaque index (PI) was assessed on the 6 Ramfjord teeth. RESULTS: Probing caused bacteremia of oral origin in 8 (40%) of the periodontitis patients and 2 (10%) of the gingivitis patients. Streptococcus spp. were the most common isolates in both groups. Compared with the gingivitis group the odds ratio (OR) for bacteremia in the periodontitis group was 5.993 (95% CI 1.081 to 33.215). Bleeding on probing (OR 1.025, 95% CI 1.004 to 1.047) and mean probing depth per tooth (OR 1.444, 95% CI 1.055 to 1.977) were significantly associated with bacteremia. No significant correlations were found between bacteremia and age, number of teeth probed, smoking status, PI, or total probing depth. CONCLUSIONS: Patients with untreated adult periodontitis are at greater risk of bacteremia due to periodontal probing than patients with chronic gingivitis. For individuals at risk of infective endocarditis, radiographic assessment prior to periodontal probing would be advisable to identify those with periodontitis so that appropriate antibiotic prophylaxis can be provided.

Treatment of canine leproid granuloma syndrome: preliminary findings in seven dogs.

OBJECTIVE: To determine effective treatment strategies for patients with refractory canine leproid granuloma syndrome. DESIGN: Multi-institutional retrospective/prospective case series using client-owned dogs. PROCEDURE: Seven dogs (four Boxers, one Dobermann, one Bullmastiff and one Bullmastiff cross-bred; ages 3 to 11 years) with leproid granulomas were treated successfully using a variety of treatment regimens. These cases were recruited because: lesions were either widely distributed over the dog; progressive, despite routine therapy, or were associated with particularly disfiguring lesions. The treatment regimen evolved during the course of the clinical study. RESULTS: Combination therapy using rifampicin (5 to 15 mg/kg p.o., every 24 h) and clarithromycin (8 to 24 mg/kg p.o. daily; dose divided every 8 or every 12 h) was used most frequently and proved to be effective and free from side effects. Total daily doses of clarithromycin in excess of 14 mg/kg were considered optimal and long treatment courses, in the order of 1 to 3 months, were used. Combination therapy using rifampicin (25 mg/kg; that is, higher than the recommended dose) and clofazimine was effective in one case, but resulted in hepatotoxicity. A topical formulation of clofazimine in petroleum jelly was used as an adjunct to oral rifampicin and doxycycline in another patient treated successfully. CONCLUSION: Based on our evolving clinical experience, a combination of rifampicin (10 to 15 mg/kg p.o., every 24 h) and clarithromycin (15 to 25 mg/kg p.o. total daily dose; given divided every 8 to 12 h) is currently recommended for treating severe or refractory cases of canine leproid granuloma syndrome. Treatment should be continued (typically for 4 to 8 weeks) until lesions are substantially reduced in size and ideally until lesions have resolved completely. A topical formulation, containing clofazimine in petroleum jelly may be used as an adjunct to systemic drug therapy. Further work is required to determine the most cost effective treatment regimen for this condition.

Dexmedetomidine: a novel sedative-analgesic agent.

Since the first report of clonidine, an alpha2-adrenoceptor agonist, the indications for this class of drugs have continued to expand. In December 1999, dexmedetomidine was approved as the most recent agent in this group and was introduced into clinical practice as a short-term sedative (<24 hours). Alpha2-adrenoceptor agonists have several beneficial actions during the perioperative period. They decrease sympathetic tone, with attenuation of the neuroendocrine and hemodynamic responses to anesthesia and surgery; reduce anesthetic and opioid requirements; and cause sedation and analgesia. They allow psychomotoric function to be preserved while letting the patient rest comfortably. With this combination of effects, alpha2-adrenoceptor agonists may offer benefits in the prophylaxis and adjuvant treatment of perioperative myocardial ischemia. Furthermore, their role in pain management and regional anesthesia is expanding. Side effects consist of mild to moderate cardiovascular depression, with slight decreases in blood pressure and heart rate. The development of new, more selective alpha2-adrenoceptor agonists with improved side effect profiles may provide a new concept for the administration of perioperative anesthesia and analgesia. This review aims to give background information to improve understanding of the properties and applications of the novel alpha2-adrenoceptor agonist, dexmedetomidine.

Mycobacterium genavense infection in two aged ferrets with conjunctival lesions.

Mycobacterium genavense infection was diagnosed in two adult ferrets. Disseminated mycobacteriosis was diagnosed in a castrated 5-year-old sable ferret with generalised peripheral lymph node enlargement and a proliferative lesion of the conjunctiva of the nictitating membrane. The diagnosis was based on characteristic cytology and sequence analysis of the 16S rRNA gene amplified using the polymerase chain reaction from fresh biopsy material. Therapy with rifampicin, clofazimine and clarithromycin probably cured the infection. An entire 4-year-old female ferret with conjunctival swelling, serous ocular discharge and swelling of the subcutaneous tissues of the nasal bridge was diagnosed as having M genavense infection on the basis of typical cytology, histopathology and sequence analysis of 16S rRNA amplicons from formalin-fixed paraffin-embedded tissue. This patient was treated successfully using rifampicin. Both ferrets subsequently died as a result of other disease conditions, 10 and 4 months following initiation of therapy, respectively. This is the first report documenting M genavense as a cause of disseminated mycobacterial disease in ferrets. Conjunctival involvement may be a feature of disseminated mycobacteriosis in the ferret. The possibility that these infections were the consequence of a ferret retrovirus infection should be considered further.

Evaluation of the cleaning and disinfection efficacy of the DEKO-190; award-based automated washer/disinfector.

The DEKO-190 Washer-Disinfector combines both automatic washing and thermal disinfection functions and is designed for the decontamination of ward utensils (such as bedpans and urine bottles) and instruments used in minor surgery prior to sterilization. We undertook a microbiological evaluation of the disinfection efficacy of the machine, using its short wash plus disinfection programme and sealed suspensions of test organisms placed at various points within the instrument. Suspensions of Enterococcus faecalis and Poliovirus were totally inactivated, the counts of aerobic organisms within a stool specimen being reduced by a factor of 10(4)whilst spores of Clostridium perfringens were unaffected. The cleaning efficacy of the DEKO-190 was also evaluated under clinical conditions by visual inspection and was found to be satisfactory. Ward-based combined washer-disinfection machines, such as the DEKO-190, have the potential to improve the efficacy of cleaning protocols within healthcare institutions.

Chronic pneumonia caused by Mycobacterium thermoresistibile in a cat.

Mycobacterium thermoresistibile was isolated in pure culture from ultrasound-guided pulmonary aspirates taken from a young cat with severe, chronic, pyogranulomatous pneumonia. Thoracic radiography and ultrasonography before therapy demonstrated severe diffuse alveolar disease. Twelve months combination therapy with doxycycline, rifampicin and clarithromycin resolved the infection. Thoracic radiographs taken at the completion of therapy showed multifocal pulmonary mineralisation. M thermoresistibile has been infrequently reported as a human or animal pathogen. This is the first reported pulmonary infection by M thermoresistibile in a cat and documents the successful treatment of the organism in a feline patient.

Surgical wound infection surveillance: the importance of infections that develop after hospital discharge.

BACKGROUND: The aim of this study was to evaluate two methods of post-discharge surgical wound surveillance and to compare the incidence and outcomes of wound infections that develop prior to patients' discharge with those that develop after hospital discharge. METHODS: One thousand, three hundred and sixty inpatients who underwent major elective surgery in an 800-bed teaching hospital in western Sydney between February 1996 and July 1997 were followed prospectively. Pre-discharge wound surveillance was performed by clinical assessment by an independent researcher on the fifth (or later) postoperative day. Post-discharge wound surveillance was performed by a mail out of questionnaires completed independently by patients and surgeons. RESULTS: Overall, 138 wound infections were diagnosed (incidence 10.1%), of which fewer than one-third (n = 44) were diagnosed before discharge (average 10.4 days postoperatively) and the remainder (n = 94) after discharge (average 20.6 days postoperatively). Seven hundred and eighty-two (57.5%) post-discharge survey forms were returned by patients and 680 (50.0%) by surgeons. When forms were returned by both surgeons and patients for the same wound (641 cases), there was substantial agreement in diagnosing infection or no infection (kappa = 0.73). CONCLUSIONS: The majority of nosocomial surgical wound infections develop after the patients' discharge from hospital. A post-discharge surveillance programme including self-reporting of infections by patients and return of questionnaires by patients and surgeons is feasible in an Australian hospital setting. However, such a programme is labour and resource intensive and strategies to increase return of questionnaires are required.

Regulation of CCAAT/Enhancer binding protein, interleukin-6, interleukin-6 receptor, and gp130 expression during myocardial ischemia/reperfusion.

BACKGROUND: Interleukin (IL)-6 is elevated in myocardium after ischemia and reperfusion. The IL-6 promoter/enhancer region contains response elements for nuclear factor-kappaB, AP-1, and CCAAT/enhancer binding protein (C/EBP). Expression and regulation of C/EBP in rat myocardium after ischemia and reperfusion has not been defined, nor has the behavior of the specific IL-6 receptor (IL-6R) or the signal transducer gp130. METHODS AND RESULTS: C/EBP DNA binding activity was not detected in shams or in previously ischemic tissue at 15 minutes of reperfusion; it was detected at 30 minutes of reperfusion, increased at 1 hour of reperfusion, and declined by 6 hours of reperfusion. A supershift was observed with anti-C/EBP-beta but not with anti-alpha or anti-delta antibodies. mRNA and protein levels of IL-6 and gp130 were detected at low levels in controls, increased at 1 hour of reperfusion, and remained high until 6 hours of reperfusion. IL-6R mRNA and protein were not detected in controls, but its mRNA was induced at 1 hour of reperfusion and its protein at 2 hours of reperfusion. Although effects of reperfusion were rapid, in ischemic tissue not reperfused, low levels of C/EBP were detected at 4 hours, and at 24 hours the levels were slightly elevated. Significant upregulation in IL-6, IL-6R, and gp130 occurred only at 24 hours of sustained ischemia. CONCLUSIONS: Reperfusion after a brief period of ischemia caused induction of myocardial C/EBP (beta-subunit). The rapid and sustained production of IL-6 with concomitant expression of IL-6 receptor and gp130 suggest that these factors may participate in a local inflammatory cascade after myocardial ischemia and reperfusion.

Subcutaneous granuloma caused by Mycobacterium avium complex infection in a cat.

A localised subcutaneous swelling developed on the nasal bridge of a cat receiving chemotherapy for alimentary tract lymphosarcoma. Cytological and histological examination of representative samples of the lesion demonstrated pyogranulomatous inflammation and abundant acid-fast bacilli. A Mycobacterium sp was cultured from tissue excised from the lesion. Extensive testing at three reference laboratories indicated the strain was a member of the Mycobacterium avium complex. The infection was treated successfully by cytoreductive surgery and a 6 weeks course of orally administered clofazimine.

Pseudoepidemic of Legionella pneumophila serogroup 6 associated with contaminated bronchoscopes.

An investigation of a pseudoepidemic of Legionella pneumophila serogroup 6 contaminating bronchoalveolar lavage specimens traced the source to contaminated tap water used to rinse disinfected bronchoscopes. The problem recurred despite plumbing changes and the installation of filters in the endoscopy unit water system because of inadequate maintenance of the filters.

Managing HIV. Part 7: Professional issues. 7.1 HIV infection control in medical practice.

Reports of cross-infection with HIV and hepatitis C during routine surgery in Sydney have refocused attention on preventing transmission of HIV and other blood-borne viruses in the health care setting. This review examines the risks of transmission in medical practice, summarises infection control measures and examines issues regarding the HIV-infected health care worker.

Replacement therapy: arginine vasopressin (AVP), growth hormone (GH), cortisol, thyroxine, testosterone and estrogen.

Replacement therapy is routinely used to treat hormone deficiencies of patients who have had surgery or radiation therapy that damages the hypothalamus or pituitary gland. Hormones commonly replaced include: arginine vasopressin (AVP), growth hormone (GH), cortisol, thyroxine (T4), testosterone and estrogen. AVP, synthesized in the hypothalamus, is stored in and released by the posterior lobe of the pituitary gland. GH is synthesized and released by the anterior pituitary gland. The other hormones are produced and released by target glands each of which is stimulated by a specific anterior pituitary hormone, which in turn is controlled by release of a specific hypothalamic hormone. Feedback control by a high circulating concentration of the target gland's hormone regulates hypothalamic hormone release. Deficiency of AVP, important for water balance in the body, is restored with the synthetic analogue, 1-desamino-8-D-arginine vasopressin (DDAVP); it is given as a nasal spray or by injection. GH is required for normal growth in the developing child; recombinant GH, produced in bacteria, is injected subcutaneously. Adrenocorticotropic hormone (ACTH) controls release of cortisol which is produced by the adrenal cortex and enables the body to cope with stress; cortisol is replaced with prednisolone given orally. Thyroid stimulating hormone (TSH) controls release of the thyroid hormones, T4 and triiodothyronine (T3), which promote growth and development, and regulate energy metabolism; for replacement of T4, oral synthetic L-thyroxine is given. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) control release of testosterone, which promotes maturation of sperm and development of male sexual characteristics; replacement testosterone is administered intramuscularly. In females, FSH and LH control release of estrogens and progesterone which prepare the reproductive tract for release of the ovum, fertilization, implantation and development of the embryo, replacement by estrogen and progesterone preparations which are orally effective is given in a cyclic manner. A transdermal delivery system is available. Nursing implications include cautions and contraindications, potential problems of over-replacement, drug interactions as well as patient teaching points.