Mycobacterium fortuitum pneumonia in a cat and the role of lipid in the pathogenesis of atypical mycobacterial infections

Mycobacterium fortuitum is a saprophytic, fast-growing, nontuberculous, and nonlepromatous mycobacterium that can cause infections in animals and humans. In dogs and cats, it is one of the most common agents of ulcerative dermatitides and panniculitides caused by atypical mycobacteria. In humans, it is frequently found in lipoid pneumonias or contaminated surgical sites. We report a cat with granulomatous pneumonia caused by M fortuitum resembling lipoid pneumonia in humans. The similarity between the histopathology of the lung and skin lesions caused by this organism in dogs and cats is emphasized. We discuss the role of lipids in the pathogenesis of mycobacterioses and suggest an association between atypical mycobacteria and lipid-rich environments. We conclude that M fortuitum should be included as a differential in cases of lipid-rich pneumonias that do not respond to common antibiotics.     

Acute bronchopneumonia associated with Mycobacterium fortuitum infection in a dog

Mycobacterium fortuitum was isolated in a sample of bronchial fluid collected by transtracheal aspiration from a 1-year-old Corgi dog with a productive cough of 10 days' duration and with radiographic and cytological features of acute suppurative bronchopneumonia. The dog responded favourably to intravenous gentamicin and cephalexin for three days and a six week course of oral ciprofloxacin. Saprophytic mycobacterial pneumonia should be considered in cases of severe pulmonary consolidation in young dogs.     

Rapidly growing members of the genus Mycobacterium affecting dogs and cats

Rapidly growing members of the genus Mycobacterium were most often associated with chronic (2 to 72 months), nonhealing skin lesions of dogs and cats. Mycobacterium fortuitum (M. fortuitum) was the most commonly isolated mycobacterium obtained from these lesions, although M. chelonae-abscessus and M. flavescens were occasionally encountered. Isolates were tested in vitro to various antimicrobial agents and found to be susceptible to amikacin (100% of the isolates), cefoxitin (93.8%), ciprofloxacin (75%), clarithromycin (71.4%), doxycycline (28.6%), erythromycin (6.2%), gentamicin (68.8%), kanamycin (75%), minocycline (81.3%), streptomycin (14.3%), tobramycin (43.8%), trimethoprim/sulfonamides (57.1%), and vancomycin (15.4%).     

Pathogenicity of Mycobacterium fortuitum and Mycobacterium smegmatis to goldfish, Carassius auratus

Despite the ubiquitous presence of atypical mycobacteria in the environment and the potential risk of infection in humans and animals, the pathogenesis of diseases caused by infection with atypical mycobacteria has been poorly characterized. In this study, goldfish, Carassius auratus were infected either with the rapidly growing fish pathogen, Mycobacterium fortuitum or with another rapidly growing mycobacteria, Mycobacterium smegmatis. Bacterial persistence and pathological host response to mycobacterial infection in the goldfish are described. Mycobacteria were recovered from a high percentage of inoculated fish that developed a characteristic chronic granulomatous response similar to that associated with natural mycobacterial infection. Both M. fortuitum and M. smegmatis were pathogenic to fish. Fish infected with M. smegmatis ATCC 19420 showed the highest level of giant cell recruitment compared to fish inoculated with M. smegmatis mc(2)155 and M. fortuitum. Of the three strains of mycobacteria examined, M. smegmatis ATCC 19420 was the most virulent strain to goldfish followed by M. fortuitum and M. smegmatis mc(2)155, respectively.     

Treatment of opportunistic mycobacterial infections with enrofloxacin in cats.

Marked improvement was observed in the condition of 6 cats with opportunistic mycobacterial infections during treatment with enrofloxacin, a fluoroquinolone antibiotic. Complete remission was achieved in 3 cats after 3 to 7 weeks of treatment. The other 3 cats were euthanatized after 1 to 2 weeks of treatment for reasons not related to the treatment. Lesions did not recur within the follow-up period, which ranged from 9 to 16 months. Treatment of opportunistic mycobacterial infection in cats is complicated because many mycobacteria are resistant to antituberculosis drugs, which also can be toxic to cats, and because results of susceptibility testing with other antimicrobials do not always correlate with clinical response. Often, neither satisfactory nor long-term response is observed in cats treated surgically or with the antibiotics currently recommended. These findings suggested that enrofloxacin is effective in the treatment of infections caused by Mycobacterium smegmatis and M fortuitum var fortuitum in cats.     

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.     

Community-acquired infectious pneumonia in puppies: 65 cases (1993-2002)

OBJECTIVE: To identify causative organisms, treatment, outcome, and prognosis for dogs < 1 year old with community-acquired infectious pneumonia. DESIGN: Retrospective case series. ANIMALS: 65 dogs. PROCEDURES: Dogs were considered to have community-acquired infectious pneumonia if they had clinical signs of primary respiratory tract disease in conjunction with radiographic evidence of alveolar disease and positive results following bacterial culture of tracheal wash fluid. RESULTS: Most dogs were hypoxemic at the time of initial examination, with pulmonary function becoming worse during the first few days of hospitalization before improving; 57 (88%) dogs survived to discharge. Bordetella bronchiseptica was isolated from tracheal wash fluid from 32 (49%) dogs, and other organisms, predominantly gram-negative enteric bacteria, were isolated from the other 33 (51%). Dogs with Bordetella pneumonia were significantly younger (median, 14 vs 21 weeks), were significantly more likely to have been obtained from a pet store (19/31 vs 7/32), had been owned for a significantly shorter time prior to the onset of illness (median, 18 vs 90 days), had significantly higher PvCO2 values at initial examination (median, 48.7 vs 41.3 mm Hg), were significantly more likely to receive supplemental oxygen (25/32 vs 16/33), and had significantly longer hospitalization times (mean, 7.2 vs 4.9 days) than did dogs with pneumonia caused by any other organism. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that a type of community-acquired infectious pneumonia could be identified in dogs < 1 year old, with disease being more severe in dogs with Bordetella pneumonia than in dogs with pneumonia caused by other bacterial organisms.     

Pneumonia after intracranial surgery in dogs

OBJECTIVE: To determine factors associated with the occurrence of pneumonia after intracranial surgery in dogs. STUDY DESIGN: Retrospective cohort study. Animals-Forty-nine client-owned dogs. METHODS: The medical records of 49 dogs with space-occupying intracranial disease that underwent craniotomy were reviewed. Development of pneumonia after surgery was considered highly likely in 12 dogs (affected dogs) based on clinical signs, including acute dyspnea or coughing in association with typical radiographic findings or abnormal transtracheal wash results. Pneumonia was confirmed in 6 dogs based on necropsy findings. Affected dogs were compared with 37 dogs that did not develop pneumonia (unaffected dogs) subsequent to intracranial surgery. Based on the medical records of affected dogs, determinations were made regarding time between development of pneumonia and surgery, surgical procedure, intracranial lesion type, and intracranial lesion location. Risk factors examined for both affected and unaffected dogs included level of consciousness, body position during the postoperative recovery period, duration of anesthesia, occurrence of vomiting or regurgitation, presence of seizures, cranial nerve deficiencies, and the presence of megaesophagus before and after surgery. We also compared the feeding protocol after surgery for each group. RESULTS: Pneumonia typically occurred within the first week after surgery (median, 6.5 days); however, this was variable (range, 1-96 days). Of the factors that were present within 24 hours before the clinical signs of pneumonia, vomiting or regurgitation and megaesophagus were found to be significant risk factors. Dogs that vomited or regurgitated were 2.71 times more likely to develop pneumonia than dogs that did not. Vomiting or regurgitation occurred in 63% of the dogs that developed pneumonia in this cohort. Dogs with megaesophagus were 9.25 times more likely to develop pneumonia than dogs without megaesophagus. Seven dogs with pneumonia died. Five of these 7 dogs appeared to have died as a direct sequel to pneumonia. CONCLUSION: Dogs undergoing craniectomies for space-occupying intracranial disease may be at higher risk for development of pneumonia due to several factors, including vomiting, regurgitation, and megaesophagus.     

Pneumocystis carinii in the miniature dachshund: Case report and literature review

This article reviews Pneumocystis carinii and presents four cases in the miniature dachshund. The cases presented with hyperpnoea, tachy-pnoea and exercise intolerance. There were also clinical signs suggestive of immune incompetence in all the dogs. P carinii pneumonia was diagnosed in all four cases on transtracheal aspirate cytology. Immunological studies showed low globulin levels on serum electrophoresis, decreased lymphoblast transformation response (in the two cases that were tested) and a deficiency of immunoglobulins A, G and M. Light and electron microscopy as well as anti-canine immunoglobulin G immunoperoxidase staining studies were performed on one case which had died because of the disease. From these four cases, it appears that P carinii pneumonia in the miniature dachshund may be the result of an immunodeficiency. It does not, however, appear to be a classic primary severe combined immunodeficiency syndrome as the dogs appeared to respond to treatment, did not show growth failure and did not manifest overwhelming commensurate bacterial infections.     

Species identification of non-tuberculous mycobacteria from humans and cattle of Chad

In Chad, during a study on tuberculosis in humans and cattle, 52 non-tuberculous mycobacteria (NTM) strains were isolated. By means of INNO-LiPA, PRA-hsp65 amplification and sequencing of 16S rDNA, NTM species of 25/52 isolates were identified. M. fortuitum complex (8) was the most frequent species, followed by M. nonchromogenicum (4) and M. avium complex (4). PRA method could identify M. fortuitum 3rd variant among isolates derived from cattle specimens. This finding could confirm the existence of farcy in the Chadian cattle population as M. fortuitum 3rd variant and putitative pathogen M. farcinogenes can't be distinguished by the methods used in this study. Half of the NTM isolates could not be specified and we considered them as contaminants from the environment.     

Bilateral thyroarytenoid cartilage lateralization and vocal fold excision with mucosoplasty for treatment of idiopathic laryngeal paralysis: 67 dogs (1998-2005)

Objective— To evaluate combined bilateral thyroarytenoid cartilage lateralization, vocal fold excision, and mucosoplasty technique (BTAL) through ventral median laryngotomy for treatment of laryngeal paralysis in dogs.
Design— Retrospective study.
Animals— Dogs (n=67) with laryngeal paralysis.
Methods— Medical records were reviewed for dogs with idiopathic laryngeal paralysis that had BTAL between January 1998 and March 2005. Retrieved data included signalment, history, physical and laryngoscopic examination findings, clinicopathologic tests, and results of recheck examination findings.
Results— BTAL was performed by a single surgeon. Short-term (<6 months) follow-up information was available for 67 dogs and long-term (>12 months) for 40 dogs. Major postoperative complications were surgical failures (13; 7 short term, 6 long term) and aspiration pneumonia (1). Mean recurrence of clinical signs was at 19 weeks (range, 2–30 weeks). Minor complications occurred in 22 (33%) dogs including occasional coughing or gagging, stridorous breathing during exercise, panting, noisy or heavy breathing, and aspiration pneumonia (3 dogs) that did not require hospitalization. All owners reported an improved quality of life and had no regrets with surgical outcome.
Conclusions— BTAL is seemingly an effective procedure for treatment of laryngeal paralysis.
Clinical Relevance— BTAL is associated with a low incidence of aspiration pneumonia; however, there is substantial risk of recurrence of clinical signs associated with narrowing of the glottis. Consequently, unilateral arytenoid lateralization currently represents the accepted approach to the treatment of laryngeal paralysis.     

Complications and Long-term Results after Partial Laryngectomy for the Treatment of Idiopathic Laryngeal Paralysis in 45 Dogs

Forty-five dogs with severe respiratory signs caused by idiopathic, acquired laryngeal paralysis were treated by partial laryngectomy. The predominant postoperative complications were coughing in 28 dogs and pneumonia in 15 dogs. Eight dogs required a second operation to alleviate persistent or recurrent upper airway obstruction. Results of surgery were considered excellent in 11 dogs (25%), good in 18 dogs (40%), fair in 6 dogs (13%), and poor in 10 dogs (22%). Poorer results were obtained by surgical residents than by more experienced surgeons. Death in the immediate postoperative period was related to pneumonia (8 dogs) and laryngeal collapse (1 dog). Nine dogs died later of respiratory disease. Although partial laryngectomy is effective for the treatment of laryngeal paralysis, it is not recommended because of the high incidence of postoperative complications.     

Diffuse alveolar injury in two dogs

Proliferative interstitial pneumonia of undetermined cause was diagnosed in 2 dogs. The clinical signs in both dogs consisted primarily of acute onset, rapid breathing, and raspy lung sounds. Radiography revealed a diffuse increase in pulmonary alveolar density. In both dogs, the primary pathologic process was diffuse alveolar pneumocyte injury, and the pulmonary lesions were similar. Proliferation of type II pneumocytes (some of which were atypical mononucleated, and others multinucleated) was a prominent feature of the interstitial pneumonia. Because of the atypical features of some pneumocytes in such cases, biopsy findings may suggest a neoplastic process. Proliferative interstitial pneumonia should be included in the differential diagnosis of a diffuse pulmonary disease that is poorly responsive to medical treatment.     

CT findings in Pneumocystis carinii pneumonia in five dogs

Pneumocystis carinii pneumonia is a rare disease in dogs. It is primarily reported in cavalier King Charles spaniels and miniature dachshunds with suspected underlying immunodeficiency. This case series reports the findings in five dogs (four cavalier King Charles spaniels and one Bedlington terrier) with confirmed P. carinii pneumonia. Thoracic (CT) revealed ground glass opacity of the pulmonary parenchyma with a diffuse or multifocal distribution. The severity of this pattern was variable. Less consistent imaging findings included parenchymal bands, bronchial dilation and signs consistent with pulmonary hypertension. Four dogs recovered well with treatment and there was resolution of CT abnormalities in all dogs with follow‐up.     

Postoperative results of unilateral arytenoid lateralization for treatment of idiopathic laryngeal paralysis in dogs: 39 cases (1996-2002)

OBJECTIVE: To evaluate postoperative results for dogs with idiopathic laryngeal paralysis that underwent unilateral arytenoid lateralization (UAL). DESIGN: Retrospective case series. ANIMALS: 39 dogs with idiopathic laryngeal paralysis. PROCEDURE: Medical records were reviewed, and information on surgical technique, hospitalization time, postoperative treatment, and complications was obtained. Owners were contacted by telephone for additional information if necessary. RESULTS: In all dogs, UAL had been performed by a single surgeon who used a standard surgical technique. Long-term follow-up information was available for all 39 dogs; mean follow-up time was 29.6 months (range, 3 to 61 months). Seven (18%) dogs developed postoperative pneumonia, and 6 of the 7 recovered with treatment. Twenty-two of the 39 (56%) dogs had minor complications, including unresolved coughing or gagging, continued exercise intolerance, vomiting, and seroma formation. Owners of 35 of the 39 (90%) dogs reported an improvement in postoperative quality-of-life score. Median survival time was 12 months; only 1 dog was euthanized because of respiratory tract disease following surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that UAL will improve quality of life in most dogs with idiopathic laryngeal paralysis. However, the complication rate is high, with postoperative pneumonia being the most important major complication. Minor complications were common but did not adversely affect owner-assigned quality-of-life scores in most dogs.     

Endogenous lipoid pneumonia associated with pulmonary neoplasia in three dogs

Endogenous lipoid pneumonia is a poorly characterised condition in veterinary medicine, particularly in dogs, but it is well recognised in association with lung neoplasia in humans. This case series describes three unique cases of endogenous lipoid pneumonia associated with lung neoplasia, including clinical, imaging, cytological findings and outcome. Clinical presentation and imaging lesions can appear non-specific and may be obscured by neoplastic infiltrate and so diagnosis requires cytology or histopathology. Awareness of endogenous lipoid pneumonia in dogs with pulmonary neoplasia has an impact on staging and monitoring, treatment of clinical signs and quality of life and also aids appropriate use of antimicrobials.     

Surgical management of cricopharyngeal dysphagia in dogs: 14 cases (1989-2001)

OBJECTIVE: To determine outcome of and complications associated with cricopharyngeal myotomy or myectomy for treatment of cricopharyngeal dysphagia (CPD) in dogs. DESIGN: Retrospective study. ANIMALS: 14 dogs. PROCEDURE: Medical records of dogs with CPD that underwent cricopharyngeal myotomy or myectomy were examined. Follow-up information was obtained through telephone interviews with owners and referring veterinarians and clinical examinations when feasible. RESULTS: 16 surgical procedures were performed on the 14 dogs. Dysphagia was completely resolved immediately after surgery in 1 dog, and clinical signs did not recur (follow-up time of 8 years); a second dog also had immediate complete resolution of dysphagia, but follow-up time was only 10 days. Three dogs had transient complete resolution with a mean time to recurrence of dysphagia of 12.3 weeks (range, 2 to 36 weeks). Three dogs had permanent partial resolution. Six dogs had no improvement after surgery. Eight of the 14 dogs were euthanatized because of problems related to CPD, including persistent dysphagia (n = 8) and aspiration pneumonia (5). CONCLUSIONS AND CLINICAL RELEVANCE: The failure rate for dogs undergoing surgical treatment of CPD may be high, particularly if concurrent aspiration pneumonia or malnutrition is not addressed prior to surgery. For those dogs with concurrent diseases, more aggressive medical management, such as enteral tube feeding, may be warranted rather than surgery. In dogs with CPD complicated by other anatomic or functional conditions, such as myasthenia gravis, laryngeal paralysis, and esophageal stricture, surgery may also not be indicated.     

Outcome of and postoperative complications in dogs undergoing surgical treatment of laryngeal paralysis: 140 cases (1985-1998).

OBJECTIVE: To compare outcomes of various surgical techniques for treatment of laryngeal paralysis in dogs and determine incidence and risk factors for development of postoperative complications. DESIGN: Retrospective study. ANIMALS: 140 dogs undergoing surgical treatment for laryngeal paralysis at a veterinary teaching hospital between 1985 and 1998. PROCEDURE: Data were analyzed to determine outcome and factors influencing outcome and development of complications. Kaplan-Meier curves were constructed for survival analysis. RESULTS: Postoperative complications were documented in 48 (34.3%) dogs; 20 (14.3%) dogs died of related causes. Aspiration pneumonia was the most common complication (33; 23.6%). Seven dogs died of aspiration pneumonia > 1 year after surgery. Dogs that underwent bilateral arytenoid lateralization were significantly more likely to develop complications and significantly less likely to survive than were dogs that underwent unilateral arytenoid lateralization or partial laryngectomy. Factors that were significantly associated with a higher risk of dying or of developing complications included age, temporary tracheostomy placement, concurrent respiratory tract abnormalities, concurrent esophageal disease, postoperative megaesophagus, concurrent neoplastic disease, and concurrent neurologic disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that surgical repair of laryngeal paralysis may be associated with high postoperative complication and mortality rates. Surgical technique and concurrent problems or diseases increased the risk of complications. Dogs appeared to have a life-long risk of developing respiratory tract complications following surgical correction.     

Arterial Blood Gases in Dogs with Bacterial Pneumonia

The purpose of this study is to report the aterial blood gas findings in dogs with bacterial pneumonia. Arterial blood gas samples were collected from 62 dogs with culture-confirmed bacterial pneumonia. These results were compared with 46 normal dog arterial blood gas samples. Results demonstrated that respiratory acidosis was not a problem in dogs with pneumonia in this study. Significant evidence of hypoxemia was noted with abnormal mean values in PaO₂ (P<0.001) and the Alveolar-arterial (A-α) gradient (P<0.001).     

Postanesthetic esophageal dysfunction in 13 dogs

Thirteen dogs with postanesthetic esophageal dysfunction were identified; 10 of these animals had esophageal stricture. Regurgitation was noted in six dogs during the inciting anesthetic event. Clinical problems common to all dogs included vomiting/regurgitation and weight loss. Coughing was noted in six dogs, and aspiration pneumonia was present in four of these dogs. The associated mortality rate was 23%. The duration of symptoms ranged from 17 to 150 days, and the diagnosis was often delayed (up to 76 days from onset of clinical signs to diagnosis). Postanesthetic esophageal dysfunction was a debilitating and costly problem that developed in one dog despite current preventative treatment.