First case described in Chile of pneumonia and colitis Rhodococcus equi in a potrillo Rhodococcus equi pneumonia and colitis in a foal: First report in Chile E. Paredes1, M. V. , Dr. med. vet . ; R. GALLEGO2, M. V .
; A. M. Channel3, M. V. , M. Sc . ; O. ARAYA4, M. V. , Ph. D . ; E.
CHAHUÁN5, T. M . ; P. THOMAS5, T. M . ; J. ZAMORA5, M. V. 1Institute of Animal Pathology, Fac. Veterinary Science, Universidad Austral de Chile. Military 2Criadero Riñihue, Chilean Army. Animal 3Patología. Fac.
Of Agriculture and Veterinary. Universidad Nacional del Litoral, P. Kreder 2805, 3080 Esperanza, Santa Fe, Argentina. 4Instituto of Veterinary Clinical Sciences, Fac. Veterinary Science. 5Instituto of Microbiology, Faculty of Sciences, Universidad Austral de Chile. ; Casilla 567, Valdivia, Chile. SUMMARY Rhodococcus equi was isolated for the first time in Chile from lung sample, bronchial lymph node and mesenteric lymph node Obtained from a 3 month chronic enteritis and foal With pneumonia. Gross lesions Were Characterised by pneumonia pyogranulomatous multiple abscesses varying size. Multiple well-defined necrotic foci, 1 to 3 cm in diameter, in the mucosal surface Were of the colon, and mesenteric lymph nodes Were enlarged. Due to the infectious disease condition, it is Necessary to carry out further studies to determine STI epidemiological relevance in Chile.
Keywords: pneumonia, colitis, Rhodococcus equi foal. Key Words: pneumonia, enterocolitis, Rhodococcus equi foal. INTRODUCTION Rhodococcus equi (R. equi), formerly classified in the genus Corynebacterium as C. equi, is an important pathogen of foals being pyogranulomatous etiologic agent of bronchiolitis and ulcerative enteritis, preferably less than 6 months old young horses (Burks, 1996; Nay, 1996; Fernandez, 1997; Castagna Vargas, 1998) with abscess formation of thoracic and mesenteric lymph nodes (Knottenbelt, 1993; Lopez 1995; Van Kruiningen, 1995) also may occur joint injuries, skin, bone , eye and various viscera (Fernandez et al. , 1995; Van Kruiningen, 1995; Burks, 1996; Nay 1996). R. equi has also been isolated from healthy and diseased animals of other species, such as pigs, cattle, sheep and also in free-living animals (Bern and Lämmler, 1994; Soedarmanto et al, 1997, 1998. ). In man is gaining importance as an emerging disease, particularly in immunosuppressed individuals (Prescott, 1991; Bern and Lämmler, 1994; Fernandez et al. , 1995; Takai et al. , 1995; and Lämmler Fuhrmann, 1997).
This article aims to communicate the first isolation in the country of R. equi, describe the typical injuries and cultural characteristics and antibiotic sensitivity of germ found in a dead foal pneumonia in the Tenth Region, Chile. MATERIAL AND METHOD In a stud farm 10 cases of diarrhea as the only symptom in foals of different breeds of 20-45 days old were detected in mid-November 1995, which did not respond to therapy potentiated sulfa (sulfa + trimethoprim) for 5 days and supportive therapy (oral rehydration salts, ringer lactate serum EV, bismuth subnitrate Flumixin oral Meglumine, EV); due to inclement weather, the offspring had remained confined stabling night with their mothers in a shed for three days, without spare bed. At the end of November totaled 40 cases detected (80% of total offspring), when Salmonella sp is isolated. E. coli and from faecal samples, starting specific treatment according to antibiogram sensitivity (Advocin® and Baytril) for 4 days, with no clinical improvement in most of them. In January 1996, 14 offspring remain with diarrhea (35% of affected), 9 of which had also respiratory compromise, which were treated with gentamicin and sodium penicillin E. V. (3 times a day for 10 days), with no remission of the symptoms. It was decided to leave without antibiotic treatment to a colt race Selle Français, 90 days old, being sacrificed later. necropsy according to the technique described by Walls and Cubillos (1995) was performed, taking samples in neutral formalin 10% of affected tissues (lungs and large colon) and samples of lung, lymph node bronchial and mesenteric lymph node for microbiological examinations. To this effect it was plated on sheep blood agar and chocolate agar, later to make morphological, physiological and biochemical isolates according to described by Holt et al exam.
(1994) and Fuhrmann and Lämmler (1997). In addition, isolates were determined sensitivity to different antibiotics by conventional methods. RESULTS AND DISCUSSION a) Clinical manifestations and laboratory tests. The clinical symptomatology was characterized by watery diarrhea began at 36 days of age, with no initial respiratory compromise or alteration of physiological constants situation is described by Yager (1987) and Burks (1996), who argue that infection R . equi, diarrhea this may be the only sign. At 75 days of age, respiratory symptoms (mild cough, crackles and hissing noises cranioventral level of both lungs) and fever, similar to that described by Prescott (1991), Vivrette (1992) and Burks (1996) are detected. During the course of the disease he continued suckling foal. After initiation of respiratory symptoms blood count was performed, finding neutrofilia (10. 0 mil / microliter) with deviation to the left (N. baciliform 1. 5 mil / ul) and increased plasma fibrinogen concentration 10 g / l). The insidious presentation of the disease in this colt, characterized first by diarrhea and later by bronchopneumonia tending to chronicity and the history of other respiratory symptoms sporadically presented earlier in the stud farm, became suspicious of R.
equi infection , since the clinical characteristics coincided fully with those described in the literature (Vivrette, 1992; Knottenbelt. , 1993; Fernandez et al, 1995; Lopez, 1995; Van Kruiningen, 1995, Burks, 1996; Nay, 1996; Fernandez et al . , 1997; Vargas Castagna, 1998). b) Findings anatomical and histopathological. Necropsy performed the animal accentuated suspicion, since the postmortem examination revealed that serious injuries were confined to lungs and large colon. Both lungs were observed without collapsing, irregularly firm, with the presence of multiple nodules of varying sizes scattered all lobes and protuían into the pleural surface. When cutting the lung tissue, these nodules were observed as multiple focal and confluent areas of yellowish white color, completely replacing the lung tissue (Figure 1) and corresponding to areas of chronic inflammation, central necrosis and discrete purulent exudate. Bronchial lymph nodes were enlarged, hyperemic and exudative. Figure 1. Lung (cutting surface): confluent foci of necrosis and purulent inflammatory reaction. Lung (cut surface): large and confluent granulomas caseated. In addition, the lining of the colon showed greater number of circular ulcers, up to 3 cm in diameter, with a thick border of cream and a depressed with traces of necrotic tissue (Figure 2) center. Mesenteric lymph nodes were increased volume and had a cutting surface with great whitish exudates.
Figure 2. greater Colon: Circular mucosal ulcerations. Mucosal surface of the colon: well defined necrotic foci. Furthermore, histopathology found in the lungs the presence of large areas of necrosis with severe inflammatory reaction neutrohistiocitaria type, finding some giant cells. In turn, the more severe inflammatory bowel exhibited neutrohistiocitaria reaction type with large areas of necrosis, covering mucosa and submucosa. c) Microbiology. All lesions observed, and that characterize a disorder caused by this bacterium box, were confirmed with isolation lung, bronchial lymph nodes and mesenteric pure culture of a Gram positive bacteria and weakly acid resistant Ziehl – Neelsen modified, pleomorphic aspect cocoide (0,71,4 microns), distributed in cuneiform palisades or encapsulated. Colonies were small, 2 to 3 mm in diameter, smooth, shiny, pale mucous salmon acquired after March 4 days of culture and development in gelatin presented a strong orange. Other features are included in Table 1. TABLE 1. biochemical and physiological characteristics of R. equi strains isolated. Biochemical and physiological properties of the isolated strains.
biochemical and physiological characteristics Motility catalase gelatinase lipase urease Nitrate reduction CAMP Glucose acid Acid Lactose Acid Mannitol – +
– + + + + – – – According to the stated characteristics, it was identified as Rhodococcus equi strain, being sensitive to different antibiotics that are included in Table 2. TABLE 2. Antibiograms of the R. equi isolates. Antibiogram of the isolated R.
equi strains. Antibiotic Sensitivity Penicilinaaa Cloxacilinaa Erythromycin Lincospectin Bipencilaaa Baytrilaaaa Advocinaaa Ceftiofuraaa Resistant Resistant
Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Although considered to R. equi has a cosmopolitan distribution, they had not described in Chile infections in foals by this agent. The table causes this microorganism is generally sporadic in enzootic areas, but also outbreaks have been reported responsible for great economic losses in the stud farm, although the most common is that the infection goes unnoticed (Knottenbelt, 1993, Burks, 1996; Soedarmanto , 1998). R. equi, causing a suppurative bronchopneumonia Subacute to chronic, associated with purulent lymphadenitis, pneumonic infections that 50% are complicated by intestinal infection (Yager, 1987), especially in foals under 6 months of age and particularly those of January 3 months of life, in which it has not yet fully matured their immune system being immunocompromised adults also particularly susceptible to infection (Burks, 1996). You can not ignore that, in addition, on some occasions it is believed that viral infections may be predisposing factors, such as with equine herpesvirus type 2 (EHV-2) (Nordengrahn et al. , 1996).
Treatment of the disease is difficult, not by the resistance R. equi may have antibacterial, but rather the facultative intracellular bacteria property, a factor that probably concurred in failure of therapy instituted in previous cases, since the isolated strain was sensitive to several antibiotics (table 2), including employees at the farm, although it must be remembered that in vitro conditions are different from those in vivo, which does not allow the conclusion that the antimicrobial susceptibility test result can be the same in the animal. Also, it should be recalled that the organism quickly becomes resistant when the antibiotic is used alone, hence it is necessary to use simultaneously more than one drug in prolonged, being recommended the primary application of erythromycin and rifampin, reinforced therapy support such as dimethylsulfoxide, aminophylline and even ranitidine (Fernandez et al. , 1995; Burks, 1996). However, Gustafsson et al. (1997) report that erythromycin may induce severe colitis in horses associated with large changes in intestinal microbiota of these animals. The discovery of R. equi in the country to presume that the infection is quite widespread, causing serious problems, given the survival and development of the agent in the external environment (especially where there is overcrowding, agglomeration of fecal material and dusty environments), the different routes of transmission, the difficulty of achieving an early diagnosis by the characteristic insidious disease development and the progressive increase in the incidence denouncing the literature, are a set of attributes that make R. equi one of the most problematic pathogens, refractory to treatment and causes a high rate of mortality in foals (Higuchi et al. , 1998). It is therefore high convenience continue studies on the subject to determine the epidemiological importance in the country, not only for its role in the health of the horses, but also because it is considered an important agent of emerging infections the human species, especially in immunosuppressed people. SUMMARY Described for the first time in the country, isolation of Rhodococcus equi from an infection in a colt of 3 months old, who suffered from chronic enteritis and pneumonia.
Also, they disclosed the lesions observed in the postmortem and histopathological examination consisting of multiple pulmonary nodules with areas of chronic inflammation, central necrosis with purulent exudate and bronchial lymph nodes increased in size: hyperaemic and exudative. In addition, the large colon showed ulcerations with necrotic tissue and mesenteric lymph nodes were enlarged with great exudation, lesions which show typical features that characterize this pyogranulomatous infection of foals. As this is an emerging infectious disease, it is necessary to continue studies, in order to determine its epidemiological relevance in Chile. _________________________________ Accepted: 05/02/2000. BIBLIOGRAPHY BERN, D. , CH. Lämmler. 1994. Biochemical and serological Characteristics of Rhodococcus equi isolates from animals and humans. J. Vet.
B Med. 41: 161165. [Links] Burks, B. 1996. Managing Rhodococcus equi infections in foals. Vet. Med. 91: 656662. [Links] CASTAGNA VARGAS, A. 1998. Infecçâo Rhodococcus equi.
Quoted in RIET-CORREA, F. , A. L. Schild, M. C. MENDEZ (Eds. ). Doenças of ruminants and equines. Edit. University, Pelotas, Brazil. [Links] FERNÁNDEZ, A. S.
, S. M. Estein, P. SOTO. 1995. Rhodococcus equi: a model of immunopathology. Arch. Med. Vet. 27: 512. [Links] FERNÁNDEZ, A. S.
, J. F. PRESCOTT, V. M. NICHOLSON. Protective effect 1997. Against Rhodococcus equi infection in mice of purified IgG from horses Vaccinated With virulance associated protein (VAP) enriched antigen. Vet. Microbiol. 56: 187-192. [Links] Fuhrmann, C. , C.
Lämmler. 1997. Characterisierung von Rhodococcus equi Mensch und Pferd von isolaten. Berliner Münch. Tierarztliche Wochenschr. 110: 5459. [Links] Gustafsson, A. , V. BAVERUD, A. GUNNARSSON, M. H. Rantzien A.
Lindholm, A. , FRANKLIN, M. HORN-Rantzien. 1997. The association of erythromycin ethylsuccinatte With acute colitis in horses in Sweden. Equine Vet. J. 29: 314318. [Links] Higuchi, T. , S. TAHARAGUCHI, A. HASHIKURA, S.
Hagiwara, C. GOJO, S. Satoh M. Yoshida, S. TAKAI. 1998. Physical and serological examinations of foals at 30 and 45 days of age for early diagnosis of Rhodococcus equi infection on endemically infected farms. JAVMA 212: 776 781. [Links] HOLT, J. G. , N. R.
KRIEG, P. H. A. Sneath, J. T. Staley, S. T. WILLIAMS. 1994. Bergey’s Manual of Determinative Bacteriology. 9th Edit. Williams \x26amp; Wilkins, Baltimore, USA. [Links]
Knottenbelt, D. C. 1993. Rhodococcus equi infection in foals: a report of an outbreak on a thoroughbred stud in Zimbabwe. Vet. 132 Rec. 7985. [Links] LOPEZ, A. 1995. Respiratory System. Quoted in: CARLTON, W. W.
and M. D. Mc GAVIN. Thomson’s Special Veterinary Pathology. 2nd Edit. Mosby, St. Louis. [Links] NAY, T. S. 1996. Extra-pulmonary Rhodococcus equi in a foal throroughbred. Dog.
Vet. J. 37: 623624. [Links] NORDENGRAHN, A. , M. RUSVAI, M. MERZA, J. EKSTROM, B. Morein, S. Belak. Equine herpesvirus 1996. Type 2 (EHV-2) as a predisposing factor for Rhodococcus equi pneumonia in foals: prevention of the disease bifactorial With EHV-2 immunostimulating complexes.
Vet. Microbiol. 51: 5568. [Links] WALLS, E. , V. CUBILLOS. 1995. Manual of Necropsy in Domestic Animals. Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia. [Links] PRESCOTT, J. F.
Rhodococcus equi 1991: an Animal and human pathogen. Clinical Microbiology Reviews 4: 20-34. [Links] SOEDARMANTO, I. , R. OLIVEIRA, CH. Lämmler, H. DURRLING. 1997. Identification and epidemiological relationship of Rhodococcus equi isolated from cases of lymphadenitis in cattle. Zbl. Bak. 286: 457467.
[Links] SOEDARMANTO, I. , W. Zhicai, A. SETYAMAHANANI, CH. Lämmler. 1998. Pheno- and genotyping of Rhodococcus equi isolated from faeces of healthy horses and cattle. Res. Vet. Sci. 64: 181185. [Links]
Takai S. , Y. IMAI, N. Fukunaga, Y. UCHIDA, KAMISARA K. , Y. Sasaki, S. TSUBAKI, T. Sekizaki. 1995. Identification of virulence-associated antigens and plasmids from Rhodococcus equi in Patients With AIDS. J. Infect.
Dis. 172: 13061311. [Links] VAN Kruiningen, H. 1995. Gastrointestinal System. Quoted in: CARLTON, W. W. and M. D. Mc GAVIN. Thomson’s Special Veterinary Pathology. 2nd Edit.
Mosby, St. Louis. [Links] VIVRETTE, S. 1992. The diagnosis, treatment, and prevention of Rhodococcus equi pneumonia in foals. Vet. Med. 87: 144-149. [Links] YAGER, J. A. 1987.
The pathogenesis of Rhodococcus equi pneumonia in foals. Vet. Microbiol. 14: 225232. [Links]