Susceptibility of rapidly growing mycobacteria and Nocardia isolates from cats and dogs to pradofloxacin.

Rapidly growing mycobacteria (RGM) and Nocardiae can cause severe or refractory infections in cats and dogs. Prolonged antibacterial therapy is required to cure these infections. As fluoroquinolones have been used in combination therapy for treating RGM infections, isolates from the Mycobacterium smegmatis cluster (n=64), Mycobacterium fortuitum cluster (n=17), and M. mageritense cluster (n=2), collected from feline and canine patients, underwent susceptibility testing to pradofloxacin. The MIC(50), MIC(90) and tentative epidemiological cut-off (ECOFF) values as determined by microbroth dilution susceptibility testing that inhibited growth of the M. smegmatis and M. fortuitum clusters were 0.063, 0.125 and ≤ 0.25; and 0.125, 0.250 and ≤ 1.0 µg/mL, respectively. E-Test results showed similar trends but MICs were lower than those for microbroth dilution. In summary, pradofloxacin demonstrated effective in vitro activity against RGM isolates. Additionally, veterinary isolates of Nocardia nova (n=18), Nocardia farcinica (n=3) and Nocardia cyriacigeorgica (n=1) underwent microbroth dilution testing to ciprofloxacin, enrofloxacin and pradofloxacin. The MIC(50) and MIC(90) of pradofloxacin, ciprofloxacin and enrofloxacin that inhibited growth of Nocardia nova isolates were 2 (4), 8 (16), 16 (32) µg/mL, respectively. The tentative ECOFF values for pradofloxacin and ciprofloxacin were 32 µg/mL and for enrofloxacin 64 µg/mL. The MIC or MIC range for the three N. farcinica isolates of pradofloxacin, ciprofloxacin and enrofloxacin were 0.25-0.5, 2 and 2 µg/mL and for the single N. cyriacigeorgica isolate were 1, 4 and 4 µg/mL, respectively. On the basis on these results, fluoroquinolones appear to have limited therapeutic potential for most Nocardia infections.

Susceptibility of rapidly growing mycobacteria isolated from cats and dogs, to ciprofloxacin, enrofloxacin and moxifloxacin.

Rapidly growing mycobacteria (RGM) cause infections in cats and dogs which require prolonged antibacterial medication for resolution. In Australia, pathogens from the Mycobacterium fortuitum and Mycobacterium smegmatis clusters are responsible for most of the RGM infections in cats and dogs. As fluoroquinolones are often recommended for treating such infections, 14 M. fortuitum isolates, 51 isolates from the M. smegmatis cluster and 2 M. mageritense isolates, collected from feline and canine patients, underwent susceptibility testing to the second generation fluoroquinolones ciprofloxacin and enrofloxacin and the newer generation fluoroquinolone moxifloxacin. Using microbroth dilution, the MIC(90) of ciprofloxacin, enrofloxacin, and moxifloxacin that inhibited growth of M. fortuitum isolates were 0.500, 0.250 and 0.063 µg/mL respectively. For the M. smegmatis cluster isolates the corresponding MIC(90) was 0.500, 0.250 and 0.125 µg/mL respectively. E-test results showed similar trends but MICs were lower than those determined by microbroth dilution. Additionally, moxifloxacin was administered to 10 clinically normal cats (50mg per cat, once daily for 4 days). The plasma moxifloxacin concentration 2h after the last dose was determined by liquid chromatography as 2.2 ± 0.6 µg/mL. The plasma concentration at 2h:MIC(90) ratios for moxifloxacin for M. fortuitum and M. smegmatis cluster was 34.9 and 17.6 respectively which exceeded the recommended threshold of 10, indicating that moxifloxacin has good theoretical efficacy for treatment of those M. fortuitum and M. smegmatis infections in cats and dogs that have become refractory to other antibacterial drug classes.

Susceptibility of canine and feline Escherichia coli and canine Staphylococcus intermedius isolates to fluoroquinolones.

OBJECTIVES AND DESIGN: 1) A prospective study to determine in vitro concentrations for a range of fluoroquinolones, gentamicin and amoxycillin-clavulanate required to inhibit growth of recently collected, feline and canine Escherichia coli and canine Staphylococcus intermedius isolates. 2) A comparative retrospective study to compare the minimum inhibitory concentrations (MICs) of ciprofloxacin, enrofloxacin and amoxycillin-clavulanate for archived canine E coli and S intermedius isolates collected ten to twenty years earlier, with those for recently collected isolates. PROCEDURE: Susceptibility was assessed using disk diffusion, agar dilution susceptibility testing and Epsilometer tests (E-tests) for both recently collected and archived isolates. RESULTS: All feline E coli isolates and recently collected canine S intermedius isolates were susceptible to all fluoroquinolones. There was a statistically significant increase in the MIC range of ciprofloxacin and enrofloxacin for recently collected E coli, and in the MIC range of amoxycillin-clavulanate for recently collected S intermedius isolates compared to archived isolates. Twelve of 59 recently collected canine E coli isolates were resistant to both ciprofloxacin and enrofloxacin. Resistant canine E coli isolates were associated with complicating host or infection site factors. CONCLUSION: This is the first report comparing the MICs for all veterinary fluoroquinolones currently available in Australia for a representative sample of canine and feline E coli and canine S intermedius isolates. Importantly, this study identified 12 of 59 canine E coli isolates resistant to fluoroquinolones and identified the development of low level resistance in canine E coli to ciprofloxacin and enrofloxacin and canine S intermedius to amoxycillin-clavulanate.

Long-term outcome of therapy for 59 cats and 11 dogs with cryptococcosis.

OBJECTIVE: To determine the outcome of therapy in cats and dogs with naturally occurring cryptococcosis. Design Retrospective study of 59 cats and 11 dogs at the University Veterinary Centre Sydney from 1986 to 2004. METHOD: Following detailed analysis of case notes potential associations between patient characteristics, cryptococcal species, retroviral status (cats), disease severity and type of therapy were examined in relation to duration and success of therapy. Treatment protocols based on amphotericin B, fluconazole and itraconazole were compared. RESULTS: Seventy-six percent of feline patients were successfully treated. For cats, the presence of central nervous system disease was the only factor found to influence outcome. Cats with neurological involvement, disseminated disease or refractory disease treated with amphotericin B containing protocols did as well, on average, as cats with less severe disease treated with azole monotherapy. Amphotericin B was thus an effective agent for treating severe cases of cryptococcosis. The median cumulative dose of amphotericin B for cats cured at the first attempt was 16 mg/kg (range 7 to 23 mg/kg). The median duration of treatment required to effect a cure at first attempt was significantly shorter for fluconazole (4 months; range 1 to 8 months) than for itraconazole (9 months; range 3 to 24 months; P = 0. 0191; Mann Whitney U test). The success rate for treatment of canine cases was 55%. No factor appeared to influence disease outcome in dogs. Large cumulative doses of amphotericin B could be administered via the subcutaneous route in both species and generally with minimal nephrotoxicity. Recrudescence occurred in a significant proportion of animals, in some cases despite a reduction of serum latex cryptococcal antigen agglutination test to zero. CONCLUSION: Although the prognosis of cryptococcosis should be described as guarded, a majority of the canine and especially feline patients can be expected to be cured, although treatment is protracted and expensive.

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.

Susceptibility of bacteria from feline and canine urinary tract infections to doxycycline and tetracycline concentrations attained in urine four hours after oral dosage.

OBJECTIVES: To measure urinary concentrations of doxycycline in cats and dogs and tetracycline in dogs 4 h after conventional oral dosing and determine whether these antibiotics were present in sufficient concentrations to be effective against common feline and canine urinary tract pathogens as assessed in vitro by Epsilometer and disc diffusion antimicrobial susceptibility methods. DESIGN: A prospective study involving oral administration to clinically normal cats and dogs of doxycycline or tetracycline (dogs only) and culture of bacteria from dogs and cats with urinary tract infections to determine their susceptibility to both doxycycline and tetracycline in vitro. PROCEDURE: In the first study, nine cats and eight dogs were administered doxycycline monohydrate (5 mg/kg every 12 h) and a further eight dogs were administered tetracycline hydrochloride (20 mg/kg every 8 h) for 72 h. Blood was collected at 2 and 4 h, and urine at 4 h, after the last dose. The concentration of each agent in serum and urine was determined by modified agar diffusion. In the second study, 45 urine samples from cats and dogs with urinary tract infections were cultured. Every bacterial isolate was tested in vitro using both Epsilometer (doxycycline and tetracycline) and disc diffusion (doxycycline, tetracycline or amoxycillin-clavulanate) tests. RESULTS: Serum doxycycline concentrations in sera of cats and dogs at 2 h were 4.2 +/- 1.0 mg/mL and 3.4 +/- 1.1 mg/mL, respectively. The corresponding concentrations at 4 h were 3.5 +/- 0.7 mg/mL and 2.8 +/- 0.6 mg/mL. Urinary doxycycline concentrations at 4 h (53.8 +/- 24.4 mg/mL for cats and 52.4 +/- 24.1 mg/mL for dogs) were substantially higher than corresponding serum values. Serum tetracycline concentrations in dogs at 2 and 4 h, and in urine at 4 h, were 6.8 +/- 2.8, 5.4 +/- 0.8, 144.8 +/- 39.4 mg/mL, respectively. Most of the urinary tract pathogens (35/45) were susceptible to urinary concentrations of doxycycline and 38/45 were susceptible to tetracycline. In contrast 41/45 of all isolates were susceptible to amoxycillin-clavulanate. CONCLUSION: This is the first report of urinary concentrations of doxycycline after conventional oral administration. Concentrations attained in the urine of normal cats and dogs were sufficient to inhibit the growth of a significant number of urinary tract pathogens and thus doxycycline may be a useful antimicrobial agent for some urinary tract infections.

Retrospective study of feline and canine cryptococcosis in Australia from 1981 to 2001: 195 cases.

A retrospective study of 155 cats and 40 dogs diagnosed with cryptococcosis between 1981 and 2001 was undertaken. Age, sex, breed, clinical findings, feline immunodeficiency virus and feline leukaemia virus status (in cats), species of Cryptococcus causing disease and region of domicile were recorded. Associations between variables were tested. Male and female cats were affected equally. Age ranged from 1 to 16 years, with a preponderance of cats aged between 2 and 3 years. Siamese, Himalayan and Ragdoll breeds were over-represented. Rural cats were more frequently infected with Cryptococcus gattii. Retroviral infection was not identified as a predisposing condition and was not correlated with either species of Cryptococcus or physical findings. Most cats had signs of nasal cavity infection, which was typically localised for a substantial period before invasion of adjacent structures or dissemination. Male and female dogs were affected equally. A marked preponderance of young, large breed dogs was noted. Border Collies, Boxers, Dalmatians, Dobermann Pinschers, Great Danes and German Shepherds were over-represented. Cryptococcus species involved was not affected by place of domicile. Although nasal cavity involvement was important, the canine cohort had a greater propensity to develop secondary central nervous system involvement and disseminated disease than feline cases. There were no clinical findings in either cats or dogs which could be reliably used to distinguish disease caused by Cryptococcus neoformans variety grubii from disease caused by Cryptococcus gattii. Both Cryptococcus species appear to be primary pathogens of cats and dogs, with the upper respiratory tract presumed to be the predominant primary site of inoculation in most but not all cases.

Infections of the subcutis and skin of dogs caused by rapidly growing mycobacteria.

Nine dogs with panniculitis due to rapidly growing mycobacteria (RGM) were examined over 17 years. Dogs were two to 15 years; five were male, four were female. All were obese or in good condition. Antecedent injury, typically a dog bite or vehicular trauma, could be identified in some patients, while one bitch had hyperadrenocorticism. Infections involved different locations, although the cervicothoracic region, dorsum or flank were most often affected. Patients were systemically well, apart from one dog with pyrexia and two with pain or lameness. Cytology demonstrated pyogranulomatous inflammation, but in only one case was it possible to see acid-fast bacilli (AFB) in smears. Histology demonstrated chronic active pyogranulomatous panniculitis and dermatitis; AFB could be detected in only four specimens. Culture of aspirates or resected tissues demonstrated RGM in all cases, comprising six Mycobacterium smegmatis group and three Mycobacterium fortuitum group isolates. Resection of infected tissues, perioperative injectable antimicrobials and long courses of oral antimicrobials chosen according to susceptibility data generally effected a cure, although some cases recurred.

Successful treatment of cryptococcal pneumonia in a pony mare.

A 20-year-old Welsh Mountain Pony (212 kg) mare was initially presented for a chronic cough, fever, weight loss and low grade abdominal pain. She later developed dyspnoea, tachypnoea and exercise intolerance. The presence of multiple masses (up to 17 cm diameter) in the pulmonary parenchyma was established using lateral thoracic radiography and transthoracic ultrasonography. Encapsulated, budding yeasts were observed in smears made from transtracheal washings and needle aspirates of the pulmonary lesions. Cryptococcus gattii (synonym: Cryptococcus neoformans variety gattii; Cryptococcus bacillisporus) was cultured from the transtracheal washings and aspirates of the lung masses. The pony was successfully treated using daily intravenous infusions of amphotericin B (typically 0.5 mg/kg in 1 L 5% dextrose in water over 1 h, following premedication with 50 mg flunixin intravenously) over a 1 month period, until a cumulative dose of 3 g had been administered. Treatment was considered to be successful on the basis of progressive improvement in clinical signs, reduction in the size of pulmonary cryptococcomas, 48 kg weight gain and a reduction in the cryptococcal antigen titre from 4096 to 256, 1 year after cessation of treatment.

Limited diversity among human isolates of Bartonella henselae.

A study of 59 isolates of Bartonella henselae reveals relatively limited diversity among those of human origin (n = 28). Either of two distinct alleles of both gltA and 16S ribosomal DNA (rDNA) was found in all isolates, with a high level of congruity between 16S and gltA inheritance among proven human pathogens. Human isolates from all over Eastern Australia were most commonly 16S rDNA (Bergmans) type I, with the same gltA allele as the type strain (Houston-1). Comparable feline isolates were more commonly 16S type II, with less congruity of inheritance between 16S and gltA alleles. Previously described arbitrarily primed PCR and EagI-HhaI infrequent restriction site PCR fingerprinting techniques separated Bartonella species effectively but lacked discriminating power within B. henselae. Examination of the 16-23S intergenic spacer region revealed for several strains several point mutations as well as a repeat sequence of unknown significance which is readily detected by HaeIII restriction fragment length polymorphism analysis. The bacteriophage-associated papA gene was present in all isolates. Enterobacterial repetitive intergenic consensus PCR proved to be a useful and robust typing tool and clearly separated human isolates (including imported strains) from the majority of feline isolates. Our data are consistent with published evidence and with previous suggestions of intragenomic rearrangements in the type strain and suggest that human isolates come from a limited subset of B. henselae strains. They strengthen arguments for careful exploration of genotype-phenotype relationships and for the development of a multilocus enzyme electrophoresis and multilocus sequence typing-based approach to the phylogeny of B. henselae.

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.

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.

An immunohistochemical method that differentiates Cryptococcus neoformans varieties and serotypes in formalin-fixed paraffin-embedded tissues.

An immunohistochemical method for determining the variety of Cryptococcus neoformans in formalin-fixed paraffin-embedded tissues was developed using mAbs 471, 302 and CRND8. The method was validated primarily using veterinary patients for which both formalin-fixed lesions and a cultured isolate were available. L-Canavanine glycine bromothymol blue (CGB) agar and the 'Crypto-Check' kit were used to determine the variety and serotype, respectively, of cultured isolates. Immunohistochemistry accurately predicted the C. neoformans variety in all tissue specimens. The CGB agar method of determining C. neoformans variety gave the same result as immunohistochemistry for 30/31 specimens. For the single discordant isolate, the serotype, random amplification of polymorphic DNA profile, microscopic and colony morphology all supported the immunohistochemical staining pattern in suggesting C. neoformans var. gattii; however, the CGB agar result was at variance. Of the C. neoformans var. neoformans cases, immunohistochemistry was congruent with variety for 13/13 cases and with serotyping for 10/13 cases. The three discordant cases were classified as having some serotype D reactivity by immunohistochemistry, but were considered to be serotype A using the Crypto-Check kit. This new method should prove a valuable epidemiological tool in studies of cryptococcosis, especially in the veterinary setting where archival tissue specimens may exist but corresponding mycological data is typically absent. The versatility of this method will expand in the future as other monoclonal antibodies with different specificities are developed.

Identification by 16S rRNA gene analyses of a potential novel mycobacterial species as an etiological agent of canine leproid granuloma syndrome.

PCR amplifications of the 16S rRNA gene were performed on 46 specimens obtained from 43 dogs with canine leproid granuloma syndrome to help determine its etiology. Sequence capture PCR was applied to 37 paraffin-embedded specimens from 37 dogs, and nested PCR was attempted on DNA from 9 fresh tissue specimens derived from 3 of the 37 aforementioned dogs and from an additional 6 dogs. Molecular analyses of the paraffin-embedded tissues and fresh tissue specimen analyses were performed at separate institutions. PCR products with identical sequences over a 350-bp region encompassing variable regions 2 and 3 of the 16S rRNA gene were obtained from 4 of 37 paraffin-embedded specimens and from all 9 specimens of fresh tissue originating from 12 of the 43 dogs. Identical sequences were determined from amplicons obtained from paraffin-embedded and fresh specimens from one dog. The consensus DNA sequence, amplified from paraffin-embedded tissue and represented by GenBank accession no. AF144747, shared highest nucleotide identity (99.4% over 519 bp) with mycobacterial strain IWGMT 90413 but did not correspond exactly to any EMBL or GenBank database sequence. With a probe derived from the V2 region of the novel canine sequence, reverse cross blot hybridization identified an additional four paraffin-embedded specimens containing the same novel sequence. In total, molecular methodologies identified the proposed novel mycobacterial sequence in 16 of 43 dogs with canine leproid granuloma syndrome, indicating that the species represented by this sequence may be the principal etiological agent of canine leproid granuloma syndrome.

Infection of the subcutis and skin of cats with rapidly growing mycobacteria: a review of microbiological and clinical findings.

Mycobacteria were isolated and characterised from 49 cats with extensive infections of the subcutis and skin. Cats were generally between 3 and 10 years of age, and female cats were markedly over-represented. All isolates were rapid-growers and identified as either Mycobacteria smegmatis (40 strains) or M fortuitum (nine strains). On the basis of Etest for minimum inhibitory concentration and/or disc diffusion susceptibility testing, all strains of M smegmatis were susceptible to trimethoprim while all strains of M fortuitum were resistant. M smegmatis strains were typically susceptible to doxycycline, gentamicin and fluoroquinolones but not clarithromycin. All M fortuitum strains were susceptible to fluoroquinolones, and often also susceptible to gentamicin, doxycycline and clarithromycin. Generally, M smegmatis strains were more susceptible to antimicrobial agents than M fortuitum strains. Treatment of mycobacterial panniculitis involves long courses of antimicrobial agents, typically of 3-6 months, chosen on the basis of in vitro susceptibility testing and often combined with extensive surgical debridement and wound reconstruction. These therapies will result in effective cure of the disease. One or a combination of doxycycline, ciprofloxacin/enrofloxacin or clarithromycin are the drugs of choice for long-term oral therapy.

Asymptomatic carriage of Cryptococcus neoformans in the nasal cavity of the koala (Phascolarctos cinereus).

Over a 22-month period, sequential nasal and skin swabs were obtained from 52 healthy captive koalas (Phascolarctos cinereus) from the Sydney region. Cryptococcus neoformans was isolated in 17 koalas from 64 of 262 (24%) nasal swabs and from nine of 262 (3%) skin swabs. Prevalence of nasal colonization varied seasonally from 12% (3/25) to 38% (10/26). Cryptococcus neoformans var. gattii alone was cultured from 37, var. neoformans alone from 22 and both varieties from five nasal swabs. Of 33 koalas sampled on three or more occasions, organisms were isolated persistently from six, occasionally from eight and never from 19. Two koalas were persistently and heavily (>/=100 colonies/plate) colonized by C. neoformans var. gattii and two with var. neoformans. Isolation of C. neoformans var. gattii from the skin was low grade and sporadic. No koalas from which C. neoformans was persistently isolated showed clinical signs of cryptococcosis and all except one had a negative latex cryptococcal antigen test, therefore the nasal cavity was presumed to be colonized by, rather than infected with, C. neoformans. Preliminary observations of koalas from Coffs Harbour indicated a much higher prevalence of colonization by C. neoformans, suggesting that environmental factors influenced the extent of carriage by C. neoformans.

Serum antibody response to Cryptococcus neoformans in cats, dogs and koalas with and without active infection.

Anti-cryptococcal antibodies were measured in normal cats, dogs, horses and koalas, and cats, dogs and koalas with cryptococcosis using an enzyme immunoassay. Antibody levels were expressed as absorbance readings. Over 80% of cats and dogs with cryptococcal infection had elevated antibody levels at the time of diagnosis, during or after successful therapy. Antibody levels in these patients either remained elevated or declined slowly after treatment. For cats, anti-cryptococcal antibody levels were higher in C. neoformans var. gattii than var. neoformans infections, and lower in mild than in moderate or severe infections. The persistence of increased anti-cryptococcal antibody levels in over half of the feline and canine cases following active infection suggested the use of antibody determinations as a seroepidemiologic marker of previous infection. Consequently, antibody measurements from 'normal' animals indicated a prevalence of previous cryptococcal infection of 10% in cats and dogs, compared with 3% in horses and 5% in koalas. Preliminary studies of young animals suggested that anti-cryptococcal antibody levels were substantially lower in the young cats but not the young dogs surveyed, compared with their mature counterparts. The cut-offs used in the present work may thus be erroneously high, with a corresponding underestimation of the prevalence of inapparent cryptococcosis.

Seasonal vitamin D status of Greyhounds in Sydney.

OBJECTIVES: To survey the vitamin D status of a population of Greyhounds in New South Wales, and to establish a reference range for plasma 25(OH)D. To investigate whether any seasonal fluctuation in vitamin D status is detectable in these animals. DESIGN: Vitamin D status was assessed in Greyhounds and crossbred dogs presented to the University of Sydney for teaching purposes over a 24 month period. PROCEDURES: Plasma 25(OH)D concentration was measured as an estimate of vitamin D status. Physical examination and plasma calcium concentration were used to verify the health of the animals, particularly with respect to metabolic bone disease. RESULTS: A plasma 25(OH)D concentration range of 10 to 76 nmol/L was found in healthy adult Greyhounds. There was no sex- or season-dependent variation in vitamin D status in Greyhounds. Concentrations in crossbred dogs did not differ significantly from those in Greyhounds. CONCLUSION: The reference range for plasma 25(OH)D concentration in Greyhound dogs is similar to that previously reported for humans. It would seem that healthy dogs in the Sydney region do not exhibit a seasonal fluctuation in their vitamin D status.