Matheus V. L. Moreira

Simultaneous quantification of gatifloxacin, moxifloxacin, and besifloxacin concentrations in cornea and aqueous humor by LC-QTOF/MS after topical ocular dosing.

The fourth-generation fluoroquinolones are widely used as ophthalmic antimicrobials. This study aimed to validate a new analytical technique for simultaneous quantification of gatifloxacin, moxifloxacin, and besifloxacin concentrations in the cornea and aqueous humor by liquid chromatography (LC) coupled to quadrupole time-of-flight mass spectrometry (QTOF/MS) at 10min and 1h after instillation of topical ophthalmic antimicrobial suspensions. It was used twenty-two male dogs without ocular lesions verified by ophthalmic and histologic examinations. Methanol:water (4:1) was used for the extraction procedure for cornea and acetonitrile:water (4:1) was used for aqueous humor. The chromatographic separations were carried out on a C18 column with a linear gradient of water and methanol, both containing 0.1% formic acid. The total chromatographic run time was 4min. Mass spectrometry analyses were performed on a Xevo™ G2-S QTof tandem mass spectrometer, operated in a positive ion electrospray ionization (ESI+) mode. The retention times were approximately 1.42min for gatifloxacin, 1.87min for moxifloxacin, and 3.01min for besifloxacin. No interference peak was detected for the three tested antimicrobials in samples obtained from both cornea and aqueous humor, ensuring that the peak response was exclusive to the analyte of interest. The limit of detection for the three antimicrobials was 0.11μg/mL and the limit of quantification was 0.42μg/mL for both cornea and aqueous humor samples. At both time points post instillation of the three antimicrobials, moxifloxacin had the highest corneal concentration and besifloxacin demonstrated the highest concentration in the aqueous humor.

Acute Oesophageal Necrosis Concurrent with Leishmania chagasi Infection in a Dog

A case of acute oesophageal necrosis concurrent with Leishmania chagasi infection is reported in a 6-year-old female mixed-breed dog. The report describes clinical signs, gross and microscopical lesions and immunohistochemical findings.

Splendore-Hoeppli phenomenon in a cat with osteomyelitis caused by Streptococcus species

A 9-month-old male neutered mixed-breed cat had a history of chronic lameness of the right hind limb, which was non-responsive to antibiotic treatment. Hematologic analysis revealed marked neutrophilia and mild monocytosis. Radiography revealed extensive loss of cortical bone, and replacement with irregular and disorganized bone. There was loss of the normal cortico-medullary distinction, and the medullary cavity had an irregular radiodensity suggestive of osteomyelitis. Surgical curettage and antibiotics did not improve the clinical condition, and amputation was performed. Grossly, the skin over the right tibia was ulcerated with a viscous and granular exudate. At histopathology, there was marked diffuse pyogranulomatous dermatitis, myositis, periostitis and osteomyelitis associated with Splendore-Hoeppli phenomenon. In addition, there was marrow osteoproliferation and multifocal cortical loss, reabsorption, fibroplasia and endosteal bone formation. Gram staining revealed myriad slightly elongated Gram-positive bacteria, arranged in pairs or single chains, confirmed by polymerase chain reaction as Streptococcus species.