Bacterial diseases are common in pet birds and should be considered in the differential list of any sick bird. Inappropriate husbandry and nutrition are often contributing factors. Neonates and young birds are especially susceptible. GI and respiratory infections are most common and can lead to systemic disease.
Normal bacterial flora of companion birds include Lactobacillus , Corynebacterium , nonhemolytic Streptococcus , Micrococcus spp, and Staphylococcus epidermidis .
The most commonly reported pathogens are gram-negative bacteria ( Klebsiella , Pseudomonas , Aeromonas , Enterobacter , Proteus , and Citrobacter spp, Escherichia coli , and Serratia marcescens ). Pasteurella spp have been reported as possible septicemic agents in birds attacked by pet cats or rats. Mycobacterium and Chlamydia are common intracellular bacterial pathogens. Infections with Salmonella spp are occasionally seen.
The most common gram-positive bacterial pathogens are Staphylococcus aureus , S intermedius , Clostridium , Enterococcus , Streptococcus , and other Staphylococcus spp. Methicillin-resistant S aureus (MRSA) is rare but has been documented. Mycoplasma spp have been implicated in chronic sinusitis, often found in cockatiels. This organism is difficult to culture, and the true incidence is unknown. Staphylococci and streptococci (especially hemolytic strains) and Bacillus spp are thought to be responsible for several dermatologic conditions in psittacine birds. Staphylococci are often isolated from lesions of pododermatitis (bumblefoot) in many avian species.
Clostridial organisms are common secondary invaders of damaged cloacal tissue in birds with cloacal prolapse or papillomatosis. They are also seen in birds with proventricular dilatation disease due to decreased GI motility. Several specific syndromes of birds can arise from various species of clostridia. A Gram stain or anaerobic culture is necessary to identify these organisms.
Diagnosis is based on clinical signs and results of cytologic examination and culture of tissue or swab samples. A Gram stain is used to identify normal flora, yeast, and spore-forming bacteria. Culture is needed to identify specific organisms and their sensitivity to antimicrobials. Samples can be obtained from the respiratory, GI, urinary, and reproductive tracts. Sample sites for culture and cytology include the choanal slit, sinus, cloaca, wounds, conjunctiva, internal organs (via ultrasound-guided fine-needle aspirates, endoscopic examination, or surgery), and blood.
Treatment is based on location of infection and results of culture and sensitivity testing. See table Antimicrobials Used in Pet Birds for a partial list of frequently recommended antimicrobials.
