Long-term follow-up of laryngeal Rhinosporidium seeberi diagnosed by PCR and treated with laser ablation and voriconazole nebulization in a retired thoroughbred polo horse.

A 21-year-old retired polo Argentinian thoroughbred horse from a teaching herd was presented for a routine bronchoalveolar lavage demonstration, during which an incidental finding of a granulomatous mass on the dorsal aspect of the epiglottis was made. Rhinosporidium seeberi was suspected from a histological section obtained from an initial biopsy, and the mass was removed via laser surgery for cytology and PCR. Sequencing of the PCR amplicons confirmed the diagnosis of R. seeberi. A treatment protocol of nebulized voriconazole for 10 d postoperatively was used. Long-term follow-up required 2 more laser surgeries plus oral fluconazole to resolve the remaining fungal spores. However, 2.5 y later, there was no evidence of remaining fungal spores. Key clinical message: Horses from endemic regions can potentially be exposed to R. seeberi. Based on its travel history, this horse may have contracted the infection in South America, California, or Alberta. Treatments administered, including diode laser resection, voriconazole antifungal nebulization, and oral fluconazole administration, were successful but required repeated interventions.

Suivi à long terme du Rhinosporidium seeberi laryngé diagnostiqué par PCR et traité par ablation au laser et nébulisation au voriconazole chez un cheval de polo thoroughbred pur-sang à la retraiteUn cheval thoroughbred argentin de polo retraité de 21 ans, issu d'un troupeau d'enseignement, a été présenté pour une démonstration de lavage broncho-alvéolaire de routine, au cours de laquelle une découverte fortuite d'une masse granulomateuse sur la face dorsale de l'épiglotte a été faite. Rhinosporidium seeberi a été suspecté à partir d'une coupe histologique obtenue à partir d'une biopsie initiale, et la masse a été retirée par chirurgie au laser pour cytologie et PCR. Le séquençage des amplicons PCR a confirmé le diagnostic de R. seeberi. Un protocole de traitement au voriconazole nébulisé pendant 10 jours après l'opération a été utilisé. Le suivi à long terme a nécessité 2 autres interventions chirurgicales au laser et du fluconazole oral pour éliminer les spores fongiques restantes. Cependant, 2,5 ans plus tard, il n'y avait aucune trace de spores fongiques restantes.Message clinique clé:Les chevaux des régions endémiques peuvent potentiellement être exposés à R. seeberi. D'après ses antécédents de voyage, ce cheval pourrait avoir contracté l'infection en Amérique du Sud, en Californie ou en Alberta. Les traitements administrés, notamment la résection au laser à diode, la nébulisation antifongique au voriconazole et l'administration orale de fluconazole, ont été efficaces mais ont nécessité des interventions répétées.(Traduit par Dr Serge Messier).

Nebulization as a more efficient method than atomizer for experimental reproduction of avian colibacillosis in young chickens.

Infection and immunity studies involving genetically modified organisms (GMOs), such as gene knockout bacterial mutants, require stringent physical containment to prevent the accidental spread of these organisms into the environment. Experimental respiratory tract infection models often require the animals, for example birds, to be transported several times between a negative pressure housing isolator and a bespoke aerosol exposure chamber under positive pressure. While the exposure chamber is sealed and fitted with HEPA filters, the repeated movements of infected animals and opening of the chamber can still pose a serious risk of breaching containment of the organism in the experimental facility. In the current study, the ability of two aerosol infection protocols that expose birds to avian pathogenic E. coli (APEC) aerosols directly within the housing isolator was evaluated. Young chicks were exposed to APEC E956 within the negative pressure housing isolators using either a nebulizer or an atomizer. Birds exposed twice (days 1 and 4) to aerosols of APEC E956 produced by the nebulizer developed a rapidly progressing disease mimicking field cases of avian colibacillosis. However, birds exposed to aerosols of APEC E956 produced by an atomizer did not develop colibacillosis even after three exposures to APEC E956 on days 1, 4 and 7. Consequently, the current study reports the nebulizer was more efficacious in producing avian colibacillosis under stricter bacterial containment settings.RESEARCH HIGHLIGHTS Two aerosol exposure methods were evaluated to develop avian colibacillosis.Nebulizer method found to be more efficient in reproducing avian colibacillosis.Refined infection method can be used to study genetically modified organisms (GMOs).

Nebulization of epinephrine to reduce the severity of brachycephalic obstructive airway syndrome in dogs.

OBJECTIVE: To determine the preoperative and postoperative effect of nebulized epinephrine on brachycephalic obstructive airway syndrome (BOAS) severity in dogs. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Thirty-one client-owned pugs, French bulldogs, and English bulldogs with moderate to severe BOAS. METHODS: Whole body barometric plethysmography was used to determine BOAS severity (BOAS index; 0%-100%) prior to and after nebulization with 0.05 mg/kg epinephrine diluted in 0.9% saline preoperatively. The same protocol was repeated postoperatively (within 24 hours of surgery). RESULTS: Five dogs were excluded because they did not tolerate nebulization, and postoperative data were available for 13 dogs. Epinephrine nebulization resulted in a decreased BOAS index across all breeds of dog both before (9.6% [3.1% to -30.2%], n = 26) and after surgery (14.3% [0.9% to -24.3%], n = 13). The preoperative reduction in BOAS index was greater (17.3% [1.8% to -27.4%]) in dogs with a baseline BOAS index >70% (P = .006) and in pugs (16.9% [0.8% to -27.4%]) compared with French bulldogs (5.2% [3.1% to -30.2%], P = .03). Simple linear regression was used to identify a positive relationship between baseline BOAS index and reduction in BOAS index for pugs (n = 10, P = .001). Nausea was noted as a side effect in four dogs. CONCLUSION: Nebulized epinephrine reduced the BOAS index of dogs in this study. This effect was clinically significant in preoperative dogs with a BOAS index >70% and in dogs recovering from surgery. CLINICAL SIGNIFICANCE: This study provides evidence to support the use of nebulized epinephrine in the perioperative management of BOAS-affected dogs.

Experimental infection of pigs with H1 and H3 influenza A viruses of swine by using intranasal nebulization.

BACKGROUND: Experimental infection of pigs via direct intranasal or intratracheal inoculation has been mainly used to study the infectious process of influenza A viruses of swine (IAVs-S). Nebulization is known to be an alternative method for inoculating pigs with IAVs-S, because larger quantities of virus potentially can be delivered throughout the respiratory tract. However, there is very little data on the experimental infection of pigs by inhalation using nebulizer. In the current study, we used intranasal nebulization to inoculate pigs with 9 different IAVs-S-3 H1N1, 2 H1N2, and 4 H3N2 strains. We then assessed the process of infection by evaluating the clinical signs, nasal and oral viral shedding, and seroconversion rates of the pigs inoculated. RESULTS: Lethargy and sneezing were the predominant clinical signs among pigs inoculated with 7 of the 9 strains evaluated; the remaining 2 strains (1 H1N1 and 1 H1N2 isolate) failed to induce any clinical signs throughout the experiments. Significantly increased rectal temperatures were observed with an H1N1 or H3N2 strains between 1 and 3 days post-inoculation (dpi). In addition, patterns of nasal viral shedding differed among the strains: nasal viral shedding began on 1 dpi for 6 strains, with all 9 viruses being shed from 2 to 5 dpi. The detection of viral shedding was less sensitive from oral samples than nasal secretions. Viral shedding was not detected in either nasal or oral swabs after 10 dpi. According to hemagglutination-inhibition assays, all inoculated pigs had seroconverted to the inoculating virus by 14 dpi, with titers ranging from 10 to 320. CONCLUSIONS: Our current findings show that intranasal nebulization successfully established IAV-S infections in pigs and demonstrate that clinical signs, viral shedding, and host immune responses varied among the strains inoculated.

Inhalation Therapy in Horses.

This article discusses the benefits and limitations of inhalation therapy in horses. Inhalation drug therapy delivers the drug directly to the airways, thereby achieving maximal drug concentrations at the target site. Inhalation therapy has the additional advantage of decreasing systemic side effects. Inhalation therapy in horses is delivered by the use of nebulizers or pressured metered dose inhalers. It also requires the use of a muzzle or nasal mask in horses. Drugs most commonly delivered through inhalation drug therapy in horses include bronchodilators, antiinflammatories, and antimicrobials.

Controlling airborne cues to study small animal navigation.

Small animals such as nematodes and insects analyze airborne chemical cues to infer the direction of favorable and noxious locations. In these animals, the study of navigational behavior evoked by airborne cues has been limited by the difficulty of precisely controlling stimuli. We present a system that can be used to deliver gaseous stimuli in defined spatial and temporal patterns to freely moving small animals. We used this apparatus, in combination with machine-vision algorithms, to assess and quantify navigational decision making of Drosophila melanogaster larvae in response to ethyl acetate (a volatile attractant) and carbon dioxide (a gaseous repellant).

Localized demodicosis due to Demodex cati on the muzzle of two cats treated with inhalant glucocorticoids.

BACKGROUND: Feline demodicosis due to Demodex cati is a rare skin disease often associated with concurrent disease and generalized immunosuppression. Local immunosuppression due to the application of topical immunomodulatory drugs, such as glucocorticoids and tacrolimus, or by tumour cells has been suggested as a potential trigger for development of localized demodicosis in humans and animals. OBJECTIVES: The goal was to describe two cats with asthma that developed localized demodicosis on the muzzle as a result of chronic therapy with a glucocorticoid administered via dispensing inhaler mask. RESULTS: In both cats, the muzzle area exposed to the fluticasone-dispensing chamber exhibited patchy alopecia, mild erythema, crusting and scaling. Deep skin scraping revealed D. cati. Discontinuation or reduction of fluticasone and administration of milbemycin resulted in resolution of clinical signs within 2 months in both cats. A negative skin scrape was obtained after 7 months of milbemycin in one of the cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Demodicosis should be considered as a possible differential diagnosis in cats with primary alopecia or other skin lesions on the face exposed to inhalant glucocorticoids. Minimization of contact between the inhalant glucocorticoid and the skin can be achieved by wiping residual powder from the face and by keeping the mask tightly pressed to the skin to avoid contact with the surrounding area.

Delivery of sevoflurane to dogs using a Stephens anaesthetic machine.

OBJECTIVE: To investigate the sevoflurane concentrations produced within the Stephens anaesthetic machine circuit (vaporizer in-circle system) at different fresh gas flow rates (FGFRs), temperatures, vaporizer settings and vaporizer sleeve positions when used to anaesthetize dogs of different body sizes. STUDY DESIGN: Experimental non-blinded studies. ANIMALS: Eighteen mixed breed dogs, weights 4-39 kg. METHODS: Anaesthetic induction with propofol was followed by maintenance with sevoflurane in oxygen via the Stephens anaesthetic machine. In study 1, the vaporizer setting, temperature and circuit FGFRs were altered with the vaporizer sleeve down (n = 3), or in separate experiments, up (n = 3). Delivered (Fi'SEVO) and expired sevoflurane concentrations were recorded. Study 2 determined the vaporizer settings (sleeve up) required to achieve predetermined multiples of minimal alveolar concentration (MAC) of Fi'SEVO when sevoflurane was delivered to dogs (n = 12) of different bodyweights and at different FGFRs. RESULTS: Delivered concentrations of sevoflurane were sufficient to maintain anaesthesia in all dogs, regardless of bodyweight, FGFR, vaporizer temperature and sleeve position. Fi'SEVO increased with increasing temperature, when the vaporizer sleeve was down, when vaporizer setting was increased and when FGFR was decreased. As the FGFR increased or the dog's bodyweight decreased, higher vaporizer settings were required to produce the same Fi'SEVO. The median Stephens vaporizer settings to achieve an Fi'SEVO of 1.3 MAC ranged from 4.3 to 5.0 for a small dog (1-10 kg), 2.5 to 5.6 for a medium dog (15-25 kg) and 2.5 to 3.5 for a large dog (30-40 kg), depending on the FGFR. CONCLUSION AND CLINICAL RELEVANCE: The Stephens anaesthetic machine can deliver to dogs, weighing 4 kg and above, concentrations of sevoflurane sufficient or in excess of that required to maintain anaesthesia, at temperatures from 10 to 35 °C, FGFRs of 1 to 5 times the patient's estimated metabolic oxygen requirement and at any vaporizer sleeve position.

Study of nebulization delivery of aerosolized fluorescent microspheres to the avian respiratory tract.

This study investigated the delivery of an aerosol of monodisperse microspheres to the respiratory tract of birds following aerosol exposure. Adult domestic pigeons (Columbia livia domestica, n = 5 birds per timed treatment) were exposed to an aerosol of fluorescent 1.0 microm diameter carboxylate microspheres for 0.5, 1, 2, or 4 hr. During the aerosolization period, the birds were free-standing in a plexiglass treatment chamber and the aerosol was delivered using a commercial nebulizer. Immediately following aerosol exposure, the birds were euthanatized and the carcasses were intravenously infused with a modified paraformaldehyde/gluteraldehyde fixative. Evaluation of microsphere distribution was performed using a stereoscopic microscope with an epifluorescent module. The results from this study revealed that the amount of aerosolized particles delivered using a commercial nebulizer was proportional to exposure periods. Aerosol exposure periods of 0.5 hr or 1 hr did not result in a readily observable distribution of 1.0 microm fluorescent microspheres to the cranial thoracic, caudal thoracic, or abdominal air sac membranes. This was partly attributed to the relatively low concentration of the individual monodisperse microspheres in the aerosolized suspension. The 2- and 4-hr exposure periods resulted in readily observable deposition of the 1.0 mirom fluorescent microspheres in the cranial thoracic, caudal thoracic, or abdominal air sac membranes, with the 4-hr exposure period resulting in the greatest number of particles on the membrane surfaces. For each of the exposure periods, there was individual animal variation regarding the distribution and relative number of spheres deposited. This study demonstrates the widespread deposition of particles that had an aerodynamic equivalent diameter of approximately 1 microm and provides a better understanding of particle deposition efficiency within the respiratory system following aerosol exposure in birds.

Safe and effective aerosolization of in vitro transcribed mRNA to the respiratory tract epithelium of horses without a transfection agent.

Vaccines and therapeutics using in vitro transcribed mRNA hold enormous potential for human and veterinary medicine. Transfection agents are widely considered to be necessary to protect mRNA and enhance transfection, but they add expense and raise concerns regarding quality control and safety. We found that such complex mRNA delivery systems can be avoided when transfecting epithelial cells by aerosolizing the mRNA into micron-sized droplets. In an equine in vivo model, we demonstrated that the translation of mRNA into a functional protein did not depend on the addition of a polyethylenimine (PEI)-derived transfection agent. We were able to safely and effectively transfect the bronchial epithelium of foals using naked mRNA (i.e., mRNA formulated in a sodium citrate buffer without a delivery vehicle). Endoscopic examination of the bronchial tree and histology of mucosal biopsies indicated no gross or microscopic adverse effects of the transfection. Our data suggest that mRNA administered by an atomization device eliminates the need for chemical transfection agents, which can reduce the cost and the safety risks of delivering mRNA to the respiratory tract of animals and humans.

Influenza A viruses with truncated NS1 as modified live virus vaccines: pilot studies of safety and efficacy in horses.

REASONS FOR PERFORMING STUDY: Three previously described NS1 mutant equine influenza viruses encoding carboxy-terminally truncated NS1 proteins are impaired in their ability to inhibit type I IFN production in vitro and are replication attenuated, and thus are candidates for use as a modified live influenza virus vaccine in the horse. HYPOTHESIS: One or more of these mutant viruses is safe when administered to horses, and recipient horses when challenged with wild-type influenza have reduced physiological and virological correlates of disease. METHODS: Vaccination and challenge studies were done in horses, with measurement of pyrexia, clinical signs, virus shedding and systemic proinflammatory cytokines. RESULTS: Aerosol or intranasal inoculation of horses with the viruses produced no adverse effects. Seronegative horses inoculated with the NS1-73 and NS1-126 viruses, but not the NS1-99 virus, shed detectable virus and generated significant levels of antibodies. Following challenge with wild-type influenza, horses vaccinated with NS1-126 virus did not develop fever (>38.5 degrees C), had significantly fewer clinical signs of illness and significantly reduced quantities of virus excreted for a shorter duration post challenge compared to unvaccinated controls. Mean levels of proinflammatory cytokines IL-1beta and IL-6 were significantly higher in control animals, and were positively correlated with peak viral shedding and pyrexia on Day +2 post challenge. CONCLUSION AND CLINICAL RELEVANCE: These data suggest that the recombinant NS1 viruses are safe and effective as modified live virus vaccines against equine influenza. This type of reverse genetics-based vaccine can be easily updated by exchanging viral surface antigens to combat the problem of antigenic drift in influenza viruses.

Mechanical ventilation of six dogs anaesthetised with isoflurane or sevoflurane delivered by a Komesaroff anaesthetic machine.

After intravenous induction, six beagles were connected to a Komesaroff machine provided with a single in-circuit vaporiser and ventilated mechanically at either nine or 14 breaths/minute while anaesthetised with either isoflurane or sevoflurane. The vaporiser was initially set at position 4/4 (fully open) and the anaesthetic concentrations were measured after one and five minutes; the vaporiser was then set at the lowest setting able to maintain anaesthesia. Cardiorespiratory variables were measured throughout the study. In most cases anaesthesia was maintained at setting 1/4 with isoflurane and at setting 1.5/4 or 2/4 with sevoflurane.

Pilot study to quantify the time to clear dexamethasone from plasma and urine of adult horses following a single nebulisation.

OBJECTIVE: To quantify the time to clear dexamethasone from plasma and urine of horses following a single nebulisation. DESIGN: Experimental using six Standardbred mares. METHODS: Dexamethasone sodium phosphate (0.04 mg/kg) diluted in 0.9% sodium chloride was administered as an aerosol using a Flexineb E2® nebuliser. Blood samples (0, 2, 4, 6, 8, 10, 12, 24, 32, 48, 72 and 96 h) and urine samples (0, 1, 4, 8, 24, 32, 48, 72 and 96 h) were collected for analysis using liquid chromatography mass spectrometry. RESULTS: Maximum plasma concentrations (tmax ) were reached by the earliest detection point (2 h) after nebulisation (0.6-1.8 ng/mL), but was no longer detectable at 48 h. However, in one horse 0.1 ng/mL was found at 96 h after three consecutive readings of 0 ng/mL. The tmax in urine was reached by the earliest collection point (1 h) after nebulisation (3.2-23.8 ng/mL), but was no longer present in urine at 72 h in five horses, while detectable levels (0.1 ng/mL) were still present at 96 h in one horse. CONCLUSIONS: A single dose of 0.04 mg/kg of DSP administered as an aerosol through a FlexinebE2® mask was no longer detectable in blood at 48 h in six horses tested, but one horse returned a reading of 0.1 ng/mL at 96 h after having no detectable levels. Dexamethasone was not detectable in urine at 72 h in five horses but was detectable at a low concentration (0.1 ng/mL) at 96 h in one horse.

Comparison of anesthetic induction in cats by use of isoflurane in an anesthetic chamber with a conventional vapor or liquid injection technique.

OBJECTIVE: To compare 2 techniques for induction of cats by use of isoflurane in an anesthetic chamber. DESIGN: Prospective, randomized study. ANIMALS: 51 healthy cats. PROCEDURES: Cats were randomly allocated to 2 induction techniques. Cats were premedicated with acepromazine (0.1 mg/kg [0.045 mg/lb], SC) and buprenorphine (0.01 mg/kg [0.0045 mg/lb], SC) 30 minutes before induction. Cats were then placed into an induction chamber, and anesthetic induction was initiated. One technique involved a conventional flow-through system that used an oxygen flowmeter and an isoflurane vaporizer to flow vapors into the induction chamber. Alternatively, liquid isoflurane was injected into a vaporization tray that was mounted to the interior surface of the chamber lid. Inductions were videotaped for analysis. Five variables (head bobbing, head swinging side to side, paddling, rotating 180 degrees to 360 degrees, and rolling over or flipping) were scored to assess induction quality. Time variables recorded during induction corresponded to the interval until onset of excitatory motion, duration of excitatory motion, interval until recumbency, and interval until complete induction. RESULTS: Compared with cats anesthetized by use of a conventional vapor chamber technique, cats anesthetized by use of the liquid injection technique had a significantly shorter interval until recumbency and interval until complete induction and lower scores for quality of induction, indicating a smoother induction. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthetic induction in cats by use of a liquid injection technique was more rapid and provided a better quality of induction, compared with results for cats induced by use of a conventional vapor technique.

Evaluation of isoflurane and sevoflurane vaporizers over a wide range of oxygen flow rates.

OBJECTIVE: To examine the accuracy and precision of isoflurane and sevoflurane anesthetic vaporizers. SAMPLE POPULATION: 5 identical isoflurane and 5 identical sevoflurane vaporizers. PROCEDURES: Oxygen flow rates from 0.02 to 10 L/min were used with different vaporizer dial settings. Agent concentrations were measured at the common gas outlet by use of a refractometer. Accuracy was defined as the difference between measured agent concentrations, and dial settings were expressed as a percentage of the applied dial settings. Precision was defined as SD of the measured agent concentrations for each combination of dial setting and flow. RESULTS: Isoflurane values were generally greater than the dial settings. Accuracy of the isoflurane vaporizer was > 20% when 0.6% and 1% was dialed. Accuracy of the sevoflurane vaporizer was always within +/- 20% but decreased at 0.02 L/min flow and at combinations of high flow and high dial settings. Overall precision of the isoflurane vaporizer was better than that of the sevoflurane vaporizer. CONCLUSIONS AND CLINICAL RELEVANCE: A possible explanation for the inaccuracy of the isoflurane vaporizer may be that it was manufactured to be accurate with air but not oxygen, which must be accounted for when using the vaporizer with oxygen, especially with nonrebreathing systems. The sevoflurane vaporizer may not deliver accurate agent concentrations at high flow and high dial settings. Both vaporizers are suitable for clinical use with a wide range of oxygen flow rates if these precautions are properly addressed.

A simple device for humidification of inspired gases during volatile anesthesia in rats.

The typical setup for administering volatile anesthetics to laboratory rats does not provide for humidification of the inspired gases, although it is known that failing to provide humidification can lead to airway inflammation and impaired pulmonary function during prolonged experimental protocols. We developed a simple humidification system in which a nebulizer was inserted into the nonrebreathing circuit used with a standard isoflurane vaporizer. We show here that the nebulizer system resulted in anesthetic stability, as measured by withdrawal reflex latency. Although the isoflurane concentration in the delivered gases was reduced, the reduction was a consistent percentage of the vaporizer output throughout the anesthetic range, thereby permitting straightforward adjustment of the vaporizer output.

Comparison of Traditional and Integrated Digital Anesthetic Vaporizers.

Recent efforts have focused on mitigating anesthetic gas emissions during laboratory animal experiments. A recently developed, digitally controlled, integrated digital vaporizer (IDV) using a syringe pump has been designed to use and administer anesthetic gas to mice and rats more efficiently. The entire IDV system can be placed on a laboratory bench, requires fewer charcoal filters to act as passive scavengers when used at a low gas flow rate, and does not need compressed gas to operate, a requirement for traditional passive systems. The objective of this study was to compare isoflurane usage between a traditional vaporizer (TdV) and an IDV system at both the same settings and those recommended by the manufacturer. We used 10 C57BL/6 male mice and administered isoflurane through either nose cones or tracheal tubes connected to a pulsatile ventilator. The results showed that isoflurane usage is highly dependent on the flow rate of the carrier gas, but the IDV system was more precise and handled low flow rates (150 mL/min) better than did the TdV system. We observed only slight differences in heart rate, respiration rate, core body temperature, time to loss of the righting reflex, and recovery time between group averages for both systems when set to manufacturer-recommended settings. Although observed decreased levels of waste anesthetic gas at low flow rates are expected from the IDV system, further work is needed to assess environmental anesthetic gas levels and exposure to laboratory personnel.

Nebulised adrenaline to manage a life-threatening complication in a pug with trismus.

A 13-month-old pug with severe trismus because of suspected masticatory muscle myositis underwent anaesthesia for magnetic resonance imaging. When regurgitation occurred, the tongue was pulled from the mouth to enable suctioning but could not be repositioned into the oral cavity as it was not possible to open the mouth. Swelling due to venous congestion and a bite wound were treated using nebulised adrenaline and resolved within 2 hours allowing retraction of the tongue. The use of nebulised adrenaline offers a non-invasive method of managing this potentially life-threatening complication.

Isolation and characterization of a "phiKMV-like" bacteriophage and its therapeutic effect on mink hemorrhagic pneumonia.

The objective of this study was to investigate the potential of using phages as a therapy against hemorrhagic pneumonia in mink both in vitro and in vivo. Five Pseudomonas aeruginosa (P. aeruginosa) strains were isolated from lungs of mink with suspected hemorrhagic pneumonia and their identity was confirmed by morphological observation and 16S rDNA sequence analysis. Compared to P. aeruginosa strains isolated from mink with hemorrhagic pneumonia in 2002, these isolates were more resistant to antibiotics selected. A lytic phage vB_PaeP_PPA-ABTNL (PPA-ABTNL) of the Podoviridae family was isolated from hospital sewage using a P. aeruginosa isolate as host, showing broad host range against P. aeruginosa. A one-step growth curve analysis of PPA-ABTNL revealed eclipse and latent periods of 20 and 35 min, respectively, with a burst size of about 110 PFU per infected cell. Phage PPA-ABTNL significantly reduced the growth of P. aeruginosa isolates in vitro. The genome of PPA-ABTNL was 43,227 bp (62.4% G+C) containing 54 open reading frames and lacked regions encoding known virulence factors, integration-related proteins and antibiotic resistance determinants. Genome architecture analysis showed that PPA-ABTNL belonged to the "phiKMV-like Viruses" group. A repeated dose inhalational toxicity study using PPA-ABTNL crude preparation was conducted in mice and no significantly abnormal histological changes, morbidity or mortality were observed. There was no indication of any potential risk associated with using PPA-ABTNL as a therapeutic agent. The results of a curative treatment experiment demonstrated that atomization by ultrasonic treatment could efficiently deliver phage to the lungs of mink and a dose of 10 multiplicity of infection was optimal for treating mink hemorrhagic pneumonia. Our work demonstrated the potential for phage to fight P. aeruginosa involved in mink lung infections when administered by means of ultrasonic nebulization.

Antibiotic aerosolization: tissue and plasma oxytetracycline concentrations in parakeets.

Oxytetracycline hydrochloride (OTC) was delivered to adult parakeets by aerosolization using a DeVilbiss model 65 ultrasonic nebulizer. Trachea, lung, and plasma concentrations were ascertained at 1, 2, 4, 6, and 8 hours postaerosolization (PA). An average of 284 ml of a solution containing 2 mg OTC/ml was aerosolized over a 1-hour period into a 0.0596 M3 chamber containing 10 parakeets. The trachea and lung concentrations were more than 10 micrograms/g at 1 and 2 hours PA, had decreased to approximately 3 micrograms/g by 4 hours PA, and were below 2 micrograms/g by 8 hours. The plasma concentration never exceeded 2.6 micrograms/ml and was at 1.6 micrograms/ml by 8 hours. This study demonstrates that it is possible to achieve therapeutic concentrations of OTC by aerosolization in lung and trachea, but treatment may need to be repeated every 4-6 hours. Since the plasma concentration never reached high levels, aerosolization under the conditions of this study is not an effective way to treat systemic infections outside the respiratory tract.