Abstract
Infections, caused by multi resistant strains of microorganisms, have represented raising problems for general practitioners and veterinarians.1 Emerging instances of MRSA isolation and death from the related infections were reported recently in marine mammals.2,3 The present communication focuses on two cases of successful treatment of captive bottlenose dolphins with acute MRSA infection.
Case 1
In December, 2009, the ten-year-old captive female dolphin showed progressive decrease in nutritional activity, followed by growth of depression and flabbiness, as well as the development of the clinical presentations of gastroenteric infection. Signs of moderate dehydration and acute infectious-inflammatory process were revealed by means of hematological examination. The initial treatment, including rehydration, disintoxication, and empiric antibacterial therapy [combination of Amoxiclave (10 mg/kg PO BID) with Ciprofloxacin (20 mg/kg BID PO) followed by combination of Ceftriaxone (20mg/kg IM SID) with Amikacin (14 mg/kg IM SID)] appeared to be ineffective. The animal's general condition continued to deteriorate quickly: the signs of intoxication increased against the background of total anorexia, absence of motion activity, tachypnea, and development of abdominal discomfort symptoms. The results of the blood tests confirmed the further progression of the disease. The microbe association of MRSA and Aeromonas hydrophilia was isolated from the blowhole, and MRSA monoculture - from the dolphin's gastric juice and feces.
Taking into account the antibiotic-sensitivity of the bacteria cultured, the therapy was continued with combination of Imipenem (14 mg /kg BID IM) and Amikacin (14 mg/kg SID IM) against the background of steroids (5 day course of dexamethasone in decreasing doses, starting at 0,12 mg/kg IM SID). At first the use of the current treatment scheme appeared to be efficacious; however, by the 12th day of the disease the signs of the infection relapse were noted. The microbe association of hemolytic Pseudomonas aeruginosa and MRSA was cultured from the dolphin's blowhole, gastric juice, and feces. The isolated strain of S. aureus appeared to be resistant to all β-lactam antibiotics and highly sensitive to moxifloxacin. Based on the sensitivities of bacteria cultured to antibiotics, the therapy was successfully continued with moxifloxacin (Avelox, 7 mg/kg SID PO, 3-week course) in combination with Amikacin (previous dosage, 2-week course). After the discontinuation of antibacterial therapy the dolphin was put on few courses of probiotics (Vetom 1.1, Linex, Bifiform) with the purpose of normalization of intestinal microflora.
Case 2
In March, 2010, the nine-year-old captive female dolphin received antibacterial therapy (Amoxiclave + ciprofloxacin, same scheme as in case 1) on account of infectious-inflammatory disease with initially positive clinical and hematological dynamics. By the 11th day of the disease the signs of rapid worsening (anorexia, decrease of motion activity, depression, intensive sialorrhea, hemorrhages on the mucus membranes) appeared. The hematological data testified to the progression of infectious-inflammatory process, as well as the development of hemolytic anemia. Modification of the antibiotic therapy scheme to the combination of Imipenem with Amikacin (same doses as in case 1) didn't lead to the expected response: the general health state of the animal continued to deteriorate quickly on the background of negative dynamics of hematological indices of inflammation. The microbe association of MRSA and hemolytic Aeromonas hydrophilia was cultured from the blowhole of the animal.
Considering on the antibiotic-sensitivity of the bacteria isolated, on the 16th day of disease the treatment was continued with 6 days course of Linezolid (Zyvox 7.5 mg/kg BID PO) and Cefepime (22 mg/kg BID IM), followed by 3 weeks' course substitute with the combination of Moxifloxacin (7 mg/kg PO SID), Rifampicin (2.8 mg/kg BID PO), and Fluconazole (2.5 mg/kg BID PO). The use of such scheme appeared to be effective: the health state of the animal stabilized in 4 days time, and then started to improve gradually. For the purpose of stimulation of the immune responsiveness and hemopoiesis the treatment with the immune modulator Glutoxim (0.75 mg/kg SID IM 7 days, then, in the same dose, for 3 more weeks every other day) was successfully provided. After the discontinuation of antibacterial therapy the dolphin received pre- and probiotics for the intestinal microflora normalization.
In both cases the dolphins completely recovered clinically and hematologically as the result of the treatment carried out. The data of the microbiological survey performed after the animal's convalescence revealed the total elimination of methicillin-resistant strain of S. aureus from the dolphins' upper airways and gastrointestinal tract (with the replacement of this bacterium by non-hemolytic S. epidermidis in case 1) and, hereby, proved the effectiveness of the used antibacterial therapy. The most probable reasons of the MRSA infection's appearance in the bottlenose dolphins are discussed in the report.
Acknowledgements
The authors would like to thank Dr. Natalia V. Beloborodova, the Head of Rational Antimicrobial Therapy Division in Moscow Healthcare Department, 13th City Children's Hospital, Moscow, for support and valuable assistance.
References
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3. Schaefer AM, Goldstein JD, Reif JS. Antibiotic-resistant organisms cultured from Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting estuarine waters of Charleston, SC and Indian River Lagoon, FL. EcoHealth 2009; 6: 33–41.