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The Pathology of Macrorhabdus ornithogaster and Eimeria dunsingi (Farr, 1960) Infections in Budgerigars (Melopsittacus undulatus)

  • Burdur Mehmet Akif Ersoy University Veterinary Faculty

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The aim of this study was to describe the pathological findings in budgerigars simultaneously infected under field conditions with coccidiosis and megabacteriosis. Severe diarrhea and vomiting were observed in a budgerigar flock. Affected birds showed inappetence and loss of condition, with a flock mortality rate of 30%. At necropsy, the proventriculi and ventriculi were swollen and hyperemic, and viscous mucus and blood adhered to the mucosa. Cytological examination of Giemsa stained proventricular and ventricular tissue revealed clusters of yeast. Microscopically, mild to severe inflammatory reactions, ulcers and hemorrhage were observed in the proventriculi. Numerous large, rod shaped Macrorhabdus ornithogaster organisms had colonized the proventriculi, ventriculi and gut. The bright pink organism was easily detected in periodic acid Schiff stained sections. On microscopic examination of the feces, numerous Eimeria oocysts were observed. Histopathological examination of the gut revealed numerous coccidial organisms in epithelial cells. Eimeria dunsingi (Farr, 1960) was identified in the gut contents of the birds, based on morphological characteristics. Surviving birds were treated with amphotericin-B for megabacteriosis and with toltrazuril for coccidiosis, after which the mortalities ceased. These results demonstrated that simultaneous natural infections under field conditions can cause severe, gross histopathological lesions and high rates of mortality in birds. At the same time, this is the first report of M. ornithogaster infection in budgerigars in Turkey.
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Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013Ozmen, O.
Macrorhabdus ornithogaster was previously referred to as
Megabacteria and was once considered to be a bacterium,
however, research has conrmed that it is a yeast organism
containing a eukaryotic nucleus (1). M. ornithogaster colo-
nizes the proventriculi and ventriculi of birds (2). is or-
ganism causes a chronic wasting disease, characterized by
emaciation, weakness, high rates of morbidity and low rates
of mortality, and has been described in canaries and budgeri-
gars. Vomiting of slimy material due to acute hemorrhagic
gastritis occurs in advanced stages of the disease in budgeri-
gars (3, 4). e known host range of the organism includes
several species of poultry, other captive bird species belonging
to several orders, including psittacine and passerine cage and
aviary birds, and some free-living bird species (5).
M. ornithogaster is an anamorphic ascomycetous yeast
e Pathology of Macrorhabdus ornithogaster and Eimeria dunsingi
(Farr, 1960) Infections in Budgerigars (Melopsittacus undulatus)
Ozmen, O.,
* Aydogan, A.,
Haligur, M.,
Adanir, R.,
Kose, O.
and Sahinduran, S.
University of Mehmet Akif Ersoy, Faculty of Veterinary Medicine, Department of Pathology, Istiklal Yerleskesi , 15030,
Burdur, Turkey,
University of Mehmet Akif Ersoy, Faculty of Veterinary Medicine, Department of Parasitology, Istiklal Yerleskesi, 15030,
Burdur, Turkey.
University of Mehmet Akif Ersoy, Faculty of Veterinary Medicine, Department of Internal Medicine, Istiklal Yerleskesi,
15030, Burdur, Turkey.
*Corresponding Author: Dr.Ozlem Ozmen, University of Mehmet Akif Ersoy, Faculty of Veterinary Medicine Department of Pathology, Istiklal Yerleskesi,
15030, Burdur, Turkey, Tel: +90 248 2132170. Email:
e aim of this study was to describe the pathological ndings in budgerigars simultaneously infected
under eld conditions with coccidiosis and megabacteriosis. Severe diarrhea and vomiting were observed in
a budgerigar ock. Aected birds showed inappetence and loss of condition, with a ock mortality rate of
30%. At necropsy, the proventriculi and ventriculi were swollen and hyperemic, and viscous mucus and blood
adhered to the mucosa. Cytological examination of Giemsa stained proventricular and ventricular tissue
revealed clusters of yeast. Microscopically, mild to severe inammatory reactions, ulcers and hemorrhage
were observed in the proventriculi. Numerous large, rod shaped Macrorhabdus ornithogaster organisms had
colonized the proventriculi, ventriculi and gut. e bright pink organism was easily detected in periodic acid
Schi stained sections. On microscopic examination of the feces, numerous Eimeria oocysts were observed.
Histopathological examination of the gut revealed numerous coccidial organisms in epithelial cells. Eimeria
dunsingi (Farr, 1960) was identied in the gut contents of the birds, based on morphological characteristics.
Surviving birds were treated with amphotericin-B for megabacteriosis and with toltrazuril for coccidiosis,
after which the mortalities ceased. ese results demonstrated that simultaneous natural infections under
eld conditions can cause severe, gross histopathological lesions and high rates of mortality in birds. At the
same time, this is the rst report of M. ornithogaster infection in budgerigars in Turkey.
Keywords: Macrorhabdus ornithogaster, Eimeria dunsingi (Farr, 1960), megabacteriosis, budgerigar,
pathology, coccidiosis, treatment.
Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013
Megabacteriosis and Coccidiosis in Budgerigars
that is the only known member of its genus (6). e organ-
ism is relatively large (20-70 µm long and 1-5 µm wide), rod-
shaped to lamentous, and stains positive with Gram and
periodic acid-Schi (PAS) stains (7). Hematoxylin and eosin
staining reveals a histological appearance of the organism
in infected birds of a typical “haystack” appearance in situ.
Coccidiosis is a disease that infects all avian species, in-
cluding psittacine birds. e disease can cause hemorrhagic
diarrhea, depression, emaciation, weight loss and sometimes
death (8-11). Coccidial infections in psittacine birds may be
asymptomatic or associated with diarrheal syndromes (some-
times with blood in the droppings), emaciation, general ill
health, and systemic disease (8). Coccidial species causing
infections in aviary birds include Eimeria dunsingi (Farr,
1960), E. haematodi, Isospora psittaculae, I. serini and I. laca-
zei (12-14).
M. ornithogaster has a worldwide distribution and a wide
range of host birds, including psittacines, passerines, ratites
and poultry species (15). ere has been one report on M.
ornithogaster in laying hens, (16) however, there have been
no reports concerning M. ornithogaster infection in budgeri-
gars in Turkey. Coccidiosis is a protozoan disease and can
cause high mortality in all avian species (17). Budgerigar
breeding is rapidly becoming more popular in Turkey and
the knowledge about diseases of this species is drawing
attention. Both megabacteriosis and coccidiosis are com-
mon diseases in budgerigars but there have been no re-
ports on pathological ndings in natural and simultaneous
e aim of this study was to describe the pathological
ndings in simultaneous infections with M. ornithogaster and
E. dunsingi (Farr, 1960) in budgerigars, as well as the treat-
ment and prophylaxis of these diseases. is is the rst report
of dual infection in budgerigar in Turkey.
Deaths occurred in a colony of birds that were transported
from a hatchery 650 km away from the aviary. Seventy-ve
birds in the ock of about 250 budgerigars died, and 38
of these were presented to the Department of Pathology
University of Mehmet Akif Ersoy, for diagnosis during
the preceding three days. Eighteen of the 38 birds were
infected with both megabacteria and coccidial organisms.
Severe hemorrhagic diarrhea, depression and death were
the most common clinical symptoms. Feces usually ad-
hered around the anus (Figure 1). At necropsy, hemor-
rhages at the proventriculus and gut were observed in birds.
Coccidiosis was diagnosed in 12 birds while eight birds
were diagnosed with megabacteriosis alone. Direct mi-
croscopy of fresh impression smears of ventricular or pro-
ventricular mucosa was prepared on glass slides, unstained
and Giemsa stained preparations were examined micro-
scopically to diagnose M. ornithogaster infection. All fe-
cal impression smears without staining were examined for
any microorganism and then Fulleborn’s otation method
used for initial diagnosis of coccidiosis. A 2.5% solution of
potassium dichromate was added to feces containing the
oocysts and homogenized. e mixture was ltered and
stored in a petri dish at room temperature for sporulation.
Identication of oocysts was based on their morphological
characteristics (9, 11, 17).
For histopathological examination, tissues were xed in
10% buered formalin, processed routinely and stained with
hematoxylin and eosin (H&E). Samples from proventriculi,
ventriculi, and the gut were also stained with PAS to identify
M. ornithogaster.
e severity of gut lesions was assessed by scoring hem-
orrhages and inammatory reactions in birds with single or
dual infections. Each criterion was graded on a scale of 0 to
4 as follows: 0= no lesion, 1= focal slight, 2= focal severe, 3=
diuse slight and 4= diuse severe. Data from each animal
was analyzed statistically. One-way analysis of variance was
used to detect any dierences between the single and dual
infection groups. e non-parametric Duncan multiple com-
Figure 1: Feces around the anus, diarrhea in three budgerigars which
died from combined infection coccidiosis and megabacteriosis.
Research Articles
Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013Ozmen, O.
parison method was used to assess the statistical signicance
of dierences. Statistical analyses were performed using the
SPSS 13.0 program (SPSS Inc., Chicago, IL). A P value <
0.05 was considered as statistically signicant.
Surviving birds were treated with amphotericin-
B (Fungizone, Bristol-Myers Squibb Inc, Istanbul-
Turkey) and toltrazuril (Baycox, Bayer- Istanbul-Turkey).
Amphotericin-B was administered twice a day (0.15-0.30
mL/bird) over 30 days to treat megabacteriosis, and toltra-
zuril (1.5 mL per liter of drinking water) was administered
3 days to treat coccidiosis. In addition, 0.1% apple vinegar
(Baktat Elma Sirkesi- Bursa- Turkey) in the drinking water
was administered during 10 days with one-week intervals
three times, totally 30 days.
At necropsy, atrophy of the pectoral muscle was most com-
monly observed in dead birds aected by megabacterio-
sis. ickening of the proventricular and ventricular walls,
covering of the proventricular mucosa by thick white mu-
cus, ulceration and hemorrhage of the proventricular and
ventricular mucosa, loosening of the koilin layer and hem-
orrhage into the lumen of these organs were commonly
observed (Figure 2). In addition marked hemorrhage in
the small intestinal wall and into the lumen were also ob-
served. e most severe histopathological lesions were seen
in the proventriculus and, in some cases the ventriculus,
including penetration of organisms into the lumen of the
supercial proventricular crypts and occasionally to deep-
er parts of the glands. Inammatory reactions were also
noted. On microscopic examination of impression smears,
long, rod-shaped organisms were observed even at
magnication. ese microorganisms were lamentous
and non-branching. e morphology, staining character-
istics, and tissue localization of the microorganisms were
consistent with previous descriptions of M. ornithogaster.
Organisms close to and inltrating the epithelium were
in parallel aggregations, whereas their orientation in the
mucin layer was less organized. e characteristics of the
disease and the shape of the organisms in the ulcerated
gastric mucosa suggested a diagnosis of M. ornithogaster
At necropsy of the birds that suered from coccidiosis,
small hemorrhagic areas and blood were observed in the
small intestine (Figure 3). On microscopic examination of
the gut contents of these birds, numerous Eimeria oocysts
were seen. Histopathology of the guts of these birds revealed
numerous Eimeria organisms, with desquamation and in-
ammation of the gut wall.
e owner stated that after transport of the birds from
the hatchery to the aviary the budgerigars gradually became
emaciated and mortality increased. Birds presented with di-
arrhea and accumulation of dried feces around the cloaca,
which in some individuals formed a packed obstruction or
plug. At necropsy of the dead birds, atrophy of the pectoral
muscles was observed, with hemorrhage of the proventricu-
lar mucosa adjoining the transition to the gizzard. Blood was
also seen in the intestinal lumen. Examination of impression
smear without staining of the gut contents revealed numer-
Figure 3: Hemorrhagic areas in gut in a budgerigar, died from
combined infection.
Figure 2: ickening of the proventricular walls (arrow) and
hemorrhage of the proventricular mucosa (arrow head).
Research Articles
Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013
Megabacteriosis and Coccidiosis in Budgerigars
Figure 4: A: Numerous M. ornithogaster organisms (arrows) in Giemsa stained proventricular tissue from a budgerigar.
B: Clusters of M. ornithogaster (arrows) in the lumen of the proventriculus. Hematoxylin and eosin stain.
C: M. ornithogaster organisms show brilliant pink coloration on periodic acid-Schi stained sections.
D: Simultaneous identication of M. ornithogaster (arrow heads) and E. dunsingi (Farr, 1960) organisms (arrows) in a budgerigar
gut. Hematoxylin and eosin stain.
E: An E. dunsingi (Farr, 1960) oocyst as observed on microscopic examination of feces.
F: Sporulated oocyst of E. dunsingi (Farr, 1960).
Research Articles
Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013Ozmen, O.
ous coccidial organisms, together with very large rod-shaped
organisms. ese organisms were also observed on Giemsa
stained impression smears (Fig. 4A).
In 18 birds, M. ornithogaster organisms were observed
in the proventriculus, ventriculus and gut, together with
coccidial organisms in the small intestine. At necropsy of
these birds both proventricular-ventricular and gut lesions,
as well as inammation were observed. Younger birds, es-
pecially, died from the diseases, and death usually occurred
suddenly in simultaneously aected birds. Atrophy of the
pectoral muscle was not severe in these cases. Microscopic
examination revealed more severe hemorrhage and inl-
trations in birds with dual infections and this was statisti-
cally signicant (p<0.01) (Table 1). On histopathological
examination of the mucosa of the gizzard, massive clumps
of rod shaped organisms attached to the epithelium were vi-
sualized (Figures 4B, 4C), and these clumps were observed
throughout the proventriculus, ventriculus and gut. In some
of the birds, the organisms penetrated deeply between mu-
cosal folds and were occasionally detected in submucosal
glands (Figure 4D). Numerous coccidial organisms were
observed in the epithelial cells of the gut. Inammatory
reactions were observed in almost all organs of the gastro-
intestinal tract.
Oocysts collected from infected birds sporulated within
one week when stored at room temperature. e oocysts were
distinctly ovoid and colorless to pale blue. ey measured 25
to 35 µm (mean 29.91 µm, SD 3.34 µm)
22.5 to 27.5 µm
(mean 24.37 µm, SD 1.88 µm). e oocysts lacked a collar,
micropyle and polar cap but possessed a single eccentrically
located polar granule (Figure 4E). e oocysts were bound by
a smooth bilayered wall. e outer layer was colorless or light
brown and the inner layer was colorless or blue. Sporulated
oocysts contained four ovoid to pyriform sporocysts mea-
suring 12.5 to 15 µm
7.5 to 10 µm in diameter (Figure
4F). e sporocysts contained a prominent anterior steida
body and a large posterior residuum consisting of numerous
granules in a compact mass. e sporocysts contained two
elongate sporozoites arranged head-to-tail. e sporozoite
nuclei were located centrally next to a single large refrac-
tile granule. Based on these morphological data, only one
Eimeria spp. had infected the birds and this was the highly
pathogenic Eimeria dunsingi (Farr, 1960). e other visceral
organs were normal in appearance. ere was no mortality
after treatment of the ock.
M. ornithogaster “megabacteriosis” has been diagnosed in
many species and results in a varied spectrum of clinical
symptoms and pathologies. In some species (chickens, tur-
keys, guinea fowls) the disease has been characterized clini-
cally by emaciation, prostration, loss of appetite, cachexia and
death, with a typically chronic course. A more acute disease
was observed in nches and budgerigars (18). In budgerigars
in this study suering from megabacteriosis the symptoms
included emaciation, diarrhea, and hemorrhage of the pro-
ventriculus. e presence of characteristic large, rod-shaped
organisms supported the diagnosis (19-21).
Coccidiosis is a common disease in budgerigars and can
result in death. In this study, megabacteriosis and coccid-
iosis were found to occur concurrently. Clinical signs and
pathological ndings related to the gastrointestinal system,
and mortality was 30%. Diarrhea was more frequent than
vomiting, and coccidiosis lesions were more marked than
megabacteriosis lesions.
Postmortem ndings included proventriculitis and pro-
ventricular dilatation. Gram-positive, PAS-positive, aci-
dophilic (on Giemsa staining), rod-shaped bacteria were
identied histologically, especially in the area between the
proventriculus and the ventriculus. A diagnosis may be made
by cytological demonstration of organisms in proventricular
washings (22). In the present study, the diagnosis was made
by cytological and histological conrmation of megabacte-
riosis, and by histological and parasitological conrmation
of coccidiosis. PAS staining was performed to support the
diagnosis of megabacteriosis. e clinical and pathological
ndings were in agreement with previous studies however
due to the coccidiosis co-infection the pathology was more
severe and mortality was higher.
Eimeria dunsingi (Farr, 1960) is a highly pathogenic
Table 1: Statistical analysis and mortality in birds with single
or dual infections.
Groups n Mortality
rate (%) Hemorrhage Inltration
Coc+ Mega 18 47 2.72±1.01
Coc 12 32 1.91±0.90
Mega 8 21 1.50±0.75
P value <0.01* <0.01*
Coc: Coccidiosis, Mega: megabacteriosis,
*Dierences between mean values for groups, as indicated by dierent
letters in the same column, are statistically signicant (P < 0.01).
Research Articles
Israel Journal of Veterinary Medicine Vol. 68 (4) December 2013
Megabacteriosis and Coccidiosis in Budgerigars
Eimeria species found in parrots and budgerigars. is or-
ganism localizes in the anterior part of the gut and is com-
mon throughout the world. e endogenous developmental
stages generally localize in villus epithelium, distal to the
nucleus (14). e ndings from this study were in agreement
with previous studies on the localization and morphology of
this organism. Because of the pathogenicity of the organism,
the coccidiosis lesions were more severe than those due to
Experimental infections with pure cultures of megabac-
terium induce disease only in English standard budgerigars
and not in the common breed. ese ndings suggest that
birds vary in their susceptibility to the organism, and other
factors are involved in the pathogenesis. Spontaneous re-
covery was common in experimental cases (23). is present
study showed that simultaneous infection with M. ornitho-
gaster and E. dunsingi (Farr, 1960) can increase the sever-
ity and rate of mortality of the disease in budgerigars. e
study also indicated that when mortality in budgerigars is
high, the possibility of a coinfection should be taken into
Domestic animals are invariably transported for a variety
of reasons, and it can cause potential stress. Transport stress
may be increases the animals’ susceptibility to diseases (24)
and increase the mortality rate (25). Birds are very sensi-
tive to change, so moving can be particularly stressful for
them (13). Transportation was considered to be a predispos-
ing factor in the occurrence of disease outbreaks in birds in
this study as there was no clinical problems observed in the
hatchery and in the remaining birds. e outbreak only oc-
curred after transportation.
e prevalence of M. ornithogaster infection is highest
in captive-bred budgerigars, parrotlets and canaries, and the
disease occurs in these birds throughout the world (19, 26,
27). To the best knowledge of the authors this is the rst
report of megabacteriosis in budgerigars in Turkey. Owners
do not generally seek veterinary or laboratory assistance and
professionals may not be aware of the occurrence of exotic
bird diseases in this country, which may explain the absence
of previous reports. is study showed that M. ornithogaster
infection may have been a problem in budgerigars.
Because the pathogenic organism is a yeast, birds with
megabacteriosis show very poor responses to antibiotics,
and antifungal drugs are most commonly recommended
(27-29). e present study conrmed the benet of treat-
ment with amphotericin-B in budgerigars with megabacte-
riosis. Megabacteriosis causes an increase in the pH of the
proventricular mucus from 2.7 to 7.0-7.3 (39, 30). Because
megabacteria thrive in an alkaline environment, an alterna-
tive treatment strategy is to increase the acidity of the pro-
ventricular uid by oral administration of apple vinegar or
grapefruit juice (13). We also found that 0.01% apple vinegar
in drinking water was eective for prophylaxis. is study
also conrmed that toltrazuril is an eective treatment for
coccidiosis. e present results showed that co-infection can
cause severe lesions and increased mortality in budgerigars.
Practitioners should consider simultaneous infection in bud-
gerigars, especially in disease outbreaks with high mortality,
and when there is no response to treatment. Prophylactic
measures against megabacteriosis, such as administration of
apple vinegar, may be advisable before birds are transported
or experience other types of stress.
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Research Articles
... Yeasts had typical morphology as previously described, stained pale basophilic with HE, were approximately 200-250 microns  5-10 microns, and were uninucleate and spherical in transverse section. 4,14,15,23,26 Individual or clustered organisms were sometimes present in the lumen of the proventricular isthmus and ventriculus. Inflammation in affected budgerigars was primarily lymphoplasmacytic and histiocytic throughout the lamina propria and, when severe, also extended into the submucosa or was transmural. ...
... Gross and histologic findings in affected budgerigars were similar to those in previous reports for both M. ornithogaster infection and proventricular adenocarcinoma. 6,10,14,15,18,20,26 There appeared to be no sex predilection for either condition. However, birds diagnosed with both M. ornithogaster infection and proventricular adenocarcinoma had a shorter median life span than those diagnosed only with neoplasia (4.0 vs 6.0 years), suggesting that changes related to this comorbidity may affect longevity, such as inanition, sepsis, peritonitis, and anemia. ...
Proventricular infection with the anamorphic, ascomycetous yeast Macrorhabdus ornithogaster and disease associated with infection (macrorhabdiosis) have been widely reported in budgerigars (Melopsittacus undulatus). Proventricular adenocarcinoma has also been previously reported in this species. In a retrospective archival search of clinical cases submitted to a zoo animal and exotic pet pathology service between 1998 and 2013, a total of 28 128 avian submissions were identified, which included 1006 budgerigars kept in zoos or aviaries or as pets. Of these budgerigars, 177 were identified histologically as infected with M. orthithogaster at the time of necropsy. Histologic examination of tissues from budgerigars infected with M. orthithogaster identified an apparent continuum in the development of proventricular isthmus lesions associated with M. ornithogaster that included inflammation, mucosal hyperplasia, glandular dysplasia, and adenocarcinoma. Proventricular adenocarcinoma was identified histologically in 21 budgerigars. Budgerigars with proventricular adenocarcinoma were significantly more likely to have macrorhabdiosis than budgerigars without proventricular adenocarcinoma. Based on odds ratios for archival data, budgerigars were 41 times (95% confidence interval [CI], 33–52) more likely to have macrorhabdiosis than other avian species and 19 times (95% CI, 11–33) more likely to have proventricular adenocarcinoma than other birds. Budgerigars were 323 times (95% CI, 42–2490) more likely to be affected by both diseases simultaneously compared with other avian species. These findings suggest that macrorhabdiosis may be an associated factor for proventricular adenocarcinoma, although the explanation for this statistically significant correlation remains unknown and further investigation is warranted.
... 23 In a study by Ozmen et al. in budgerigars with macrorhabdosis, the symptoms included cachexia, diarrhea and hemorrhage of the proventriculus. 24 In the present study, 16.66% of budgerigars positive by microscopic examination and PCR method had symptoms such as regurgitation, grinding and throwing food out of the mouth, vomiting, diarrhea, lethargy, anorexia, weight loss, however, no birds died during the present study. Based on our findings in budgerigars, it seems that a chronic form of macrorhabdosis was common in budgerigars in the southern region of Iran. ...
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Macrorhabdus ornithogaster is a microorganism that causes nonspecific and general clinical symptoms and to this day, diagnosis and also treatment have been yet hard. The present study was conducted to survey the prevalence of macrorhabdosis and to characterize M. ornithogaster phylogenetically in Psittaciformes suspected of macrorhabdosis from January 2018 to May 2019 in Ahvaz, Iran. For this purpose, fecal samples were collected from Psittaciformes with signs of the disease. Wet mounts were prepared from fecal samples and examined carefully using a light microscope. Samples from parrots with gastrointestinal symptoms of the disease were chosen for molecular diagnosis of the organism and DNA was extracted from these samples. For detection of M. ornithogaster, primer sets (BIG1, Sm4) and (AGY1, Sm4) which target the 18S rDNA gene were selected and Semi-nested polymerase chain reaction (Semi-nested PCR) was performed. The PCR method confirmed the presence of M. ornithogaster in 14.00% of the samples. Purified PCR products were sequenced for more accurate confirmation and according to the gene sequence all sequences were owned by M. ornithogaster. The results disclosed a 96.03 - 100% identity when compared to other sequences of M. ornithogaster which had previously been deposited in the GenBank® from Germany and the USA. The results of this study proved the circulation of M. ornithogaster between cockatiel, budgerigar and grey parrot. The prevalence of macrorhabdosis was higher in cockatiel compared to budgerigar and grey parrot. As far as the authors know, this was the first record of macrorhabdosis in African grey parrots.
... In this study, we found two goldfinches (Carduelis carduelis) that had fecal samples positive for coinfection with M. ornithogaster and Isospora sp., which is protozoon frequently recovered in Fringillidae (Fig. 3) (12, 13). In a study conducted by Ozmen et al. (14), coinfection with M. ornithogaster and Eimeria dunsingi (a coccidial species that cause a protozoan infection with high mortality in avian species) was found in dead budgerigars (Melopsittacus undulatus), after a necropsy analysis. By using the mini-Flotac technique, we demonstrated the feasibility of investigating infections caused by M. ornithogaster and other parasites in live birds simultaneously and rapidly with a stool sample. ...
Full-text available
This study was aimed at proposing the use of a new rapid and user friendly diagnostic tool for the detection of Macrorhabdus ornithogaster in birds. The current report focuses on the diagnostic feasibility of different methods, paying particular emphasis on the application of the Mini-FLOTAC technique for diagnosis of M. ornithogaster. Mini-FLOTAC is particularly tailored for epidemiological monitoring and surveillance, where large numbers of faecal samples must be rapidly, yet reliably examined. Gram stain as standard method was used to validate the reliability of Mini-FLOTAC. This tool has not yet been used in avian species nor even in the diagnosis of yeast infections. In our study M. ornithogaster showed an excellent flotation performance never proved. Our results suggest that Mini-FLOTAC is a valid, sensitive and potentially low-cost alternative technique to use in the diagnosis of this yeast infections in birds. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
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Since 2000, Macrorhabdus ornithogaster "megabacteriosis" has been diagnosed in the avian diseases laboratory in a diversity of avian species and varied spectrum of disease. The disease in some species (chickens, turkeys, guinea fowls) was clinically characterized by emaciation, prostration, loss of appetite, cachexia and death, with a typically chronic course. A more acute disease was observed in finches (canary-Serinus and zebra-Taeniopygia) and budgerigars (Melopsittacus undulatus). The large rod shaped organism, visible from 100 times magnification, with and without staining, could be detected in sick and also in reasonably normal individuals of some species, such as chickens, turkeys, quails and pigeons. In rheas (Rhea americana), ostriches (Struthio camelus), canaries, zebra-finches, guinea-fowl (Numida meleagris) and budgerigars. The disease was severe, causing to up to 100% mortality. The infection could be detected in some species along with other infectious or disease problems, such as endoparasites (helminths, coccidia) and ectoparasitism (order Mallophaga or/and order Acarina). The cultivation of M ornithogaster was successfully achieved in solid and liquid media, originated from chickens (four isolates), guinea fowl (I isolate), chuckar partridge (I isolate) and canary (I isolate). A very interesting finding at microscopy was motility of M ornithogaster, as detected both in cultures obtained on agar for pathogenic fungi and passaged into thioglycolate broth, as well as on samples observed in wet preparations from in vivo. Differences in colony aspects were noted among the isolates. Experimental infections were attempted in chicken and japanese quail, using a chicken isolate, allowing the detection of the organism in the proventriculus and liver in apparently normal birds. One chicken isolate was injected intraperitoneally in Balb/c mice and resulted in 100% mortality.
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This study was performed on a breeding colony (about 500 budgerigars) affected by chronic fatal wasting disease. Necropsy was undertaken on ten severely affected budgerigars, and fresh-impression smears of the ventricular and proventricular mucosa were prepared and observed unstained and stained by Giemsa and Gram’s methods using light microscopy. Tissue samples for histopathology were taken from the proventriculus, gizzard, intestine, liver, spleen and lung, fixed in 10%-buffered formalin, and processed by standard paraffin wax technique. Sections were stained with H&E, Brown–Brenn and PAS methods. At necropsy, atrophy of the pectoral muscle, thickening of the proventricular and ventricular wall, covering of the proventricular mucosa by thick white mucus, ulceration and haemorrhage of the proventricular mucosa, and loosening of the koilin layer were observed. The most severe histopathological lesions were observed in the proventriculus and gizzard, especially at the proventricular–ventricular junction, including penetration of an organism to the lumen of the superficial proventricular crypts and occasionally to deeper parts of the glands; lymphocytic–plasmacytic proventriculitis, lymphocytic–plasmacytic ventriculitis and disruption of the koilin layer were also noted. The organism was gram-positive, PAS-positive and acidophilic in Gram’s, PAS and Giemsa stained sections, respectively. Other birds in the colony were treated with nystatin after which, the rate of mortality decreased and reached zero. At necropsy of treated birds, no megabacteria were observed in smears and tissue sections. In conclusion, definitive diagnosis of megabacteriosis is most consistently demonstrated by histopathology and fresh smear of the proventricular mucus. An effective treatment is antifungal agents such as nystatin. KeywordsMegabacteriosis– Macrorhabdus ornithogaster –Budgerigar–Nystatin
An organism commonly referred to as 'megabacterium' colonizes the gastric isthmus of many species of birds. It is weakly Gram-positive and periodic acid-Schiff-positive and stains with silver stains. Previous studies haveshown that it has a nucleus and a cell wall similar to those seen in fungi. Calcofluor white M2R staining suggests that the cell wall contains chitin, a eukaryote-specific substance, and rRNA in situ hybridization demonstrates that it is a eukaryote. To characterize this organism phylogenetically, DNA was extracted from purified cells. rDNA was readily amplified by PCR with pan-fungal DNA primer sets and primer sets derived from the newly determined sequence, but not with bacteria-specific primer sets. Specific primer sets amplified rDNA from isthmus scrapings from an infected bird, but not from a non-infected bird or other control DNA. The sequence was confirmed to derive from the purified organism by in situ rRNA hybridization using a specific probe. Phylogenetic analysis of sequences of the 18S rDNA and domain D1/D2 of 26S rDNA showed the organism to be a previously undescribed anamorphic ascomycetous yeast representing a new genus. The name Macrorhabdus ornithogaster gen. nov., sp. nov. is proposed for this organism. The type material is CBS 9251T (=NRRL Y-27487 T ).
"Megabacteriosis" is a condition affecting many psittacine and nonpsittacine birds for which an effective, reliable therapy and means of prevention have not been developed. Megabacteriosis has been associated with a chronic wasting condition in the budgerigar (Melopsittacus undulatus) termed "going light," but the organism also has been detected in clinically healthy, thriving birds. In this study, removing eggs from the nests of megabacteria-positive adult budgerigars and hand-raising hatchlings under isolation conditions prevented transmission of megabacteria in all offspring. Staining fecal smears and histologic tissues with Calcofluor White-M2R also was shown to be a reliable means of demonstrating megabacteria. Hand-raising budgerigar hatchlings, and those of other avian species in which megabacteriosis is considered to be of concern, is a potentially valuable method of producing offspring that are free of this organism.
Este trabalho tem como objetivo relatar a ocorrência de um agente etiológico, denominado na Europa, Australia e EUA como "megabactéria", observado em estômago de pequenas aves (canários belgas, agapornis e periquitos australianos), provenientes da região de Ribeirão Preto, Estado de São Paulo/SP. As necropsias de 64 aves silvestres (4 periquitos australianos, 12 agapornis e 48 canários), realizadas no perído de 1994 a 1997, foram analisadas, constatando-se em 56% dos casos a presença de estruturas filiformes, acidofílicas sob coloração Giemsa, gram positivas, existentes no muco do proventrículo, descritas na literatura como "megabactérias". Foram testados diversos tipos de meios de cultura para reprodução in vitro deste microrganismo. Foram ainda comparadas as dimensões (comprimento e largura) dessa bactéria obtida apartir do esfregaço fresco de muco proventricular e da "megabactéria" proveniente de cultivo in vitro. Também foram listados os principais achados macroscópicos do animais portadores desta bactéria.
This review on megabacterium and megabacteriosis emphasizes the newest knowledge regarding megabacteria which identifies them as fungi. Evidence also suggests that the strains of the organism investigated do not belong to a single taxon. Because this organism has been so difficult to culture and treat, specific microbiological parameters are described including a culture medium, which allows for successful passages of samples. Clinical, pathologic, and histopathologic details will also aid in identification of megabacterium in infected birds. The known avian host spectrum is listed to highlight the diversity of species affected by this unique organism. Most importantly, recent treatment regimens are described that have had the highest success in patient survivability.