Pakistan Vet. J., 2008, 28(1): 17-20. OCCURRENCE OF LANCEFIELD GROUP C STREPTOCOCCAL SPECIES IN STRANGLES CASES OF FOALS IN PUNJAB, PAKISTAN
S. MANZOOR, M. SIDDIQUE, SAJJAD-UR-RAHMAN AND M. ASHRAF1
Department of Microbiology, University of Agriculture, Faisalabad;
1Remount Veterinary School, Sargodha, Pakistan
ABSTRACT
Three equine rearing districts of Punjab, Pakistan including Sargodha, Okara and Faisalabad were
surveyed. The occurrence of strangles was highest in foals during February to the start of May compared to winter and summer seasons. Strangles-inflicted foals showed inability to eat, strangled breathing with roaring sounds, swollen submandibular and submaxillary lymph nodes, abscessation in the lymph nodes, hyperthermia and anorexia with general debilitating conditions. Morbidity and case fatality rates were 78 and 2%, respectively. Pus samples were collected from 70 foals showing burst lymph node abscesses and processed on blood agar. Typical growth showing pinpoint mucoid colonies, with beta hemolysis and catalase negative characteristics were subjected to API Strep 20 system. The isolates of streptococcus recovered from pus samples include S. equi subspecies equi (54%), S. equi subspecies zooepidemicus (11%), S. dysgalactia subspecies equisimilis (11%) and mixed isolates of S. equisimilis and S. equi (23%). Streptococcus species were found sensitive to Penicillin and Cefotoxime, whereas Gentamycine and Tetracycline were ineffective. Key words: Strangles, foals, SDS-PAGE, M-protein, Streptococcus species. INTRODUCTION
affected foals were investigated to verify the previously
With the development of mechanical transport, the
number of equines is decreasing in large cities of
MATERIALS AND METHODS
Pakistan but its importance is unequivocal in rural and
northern areas of the country. In many parts of the
Incidence of strangles
Pakistan, donkeys, horses and mules are the only means
Three equine rearing Districts of Punjab, Pakistan
of traveling in the remote areas (Ashraf, 2001). Equine
including Sargodha, Okara and Faisalabad were
population in the country was reported as 4.6 million
surveyed throughout the year during January to
heads, out of which 2.47 millions existed in districts
December, 2005, each month, for new cases of
Sargodha, Okara and Faisalabad of Punjab strangles in horses and mules of ages from 9 months to (Anonymous, 2006).
2 years (foals) and 2-5 years (adults). New cases of
In equines, strangles is a disease commonly
strangles during each month were included in the study
associated with fever, depression, anorexia (Sweeney et al., 1989; Dalgleish et al., 1993; Wallace et al., 1995),
purulent nasal discharge and abscessation of the lymph
Collection of pus samples
nodes of the head and neck (George et al., 1983).
From January to May 2005, a total of 70 foals (9
Mortality and morbidity associated with this disease
months to 2 years of age) with clinical signs of swollen
have been reported to be 3.6 and 62%, respectively in
submandibular lymph nodes and ruptured abscesses
an outbreak in a standard bred farm in Kentucky, USA
were approached in the equine rearing districts of
Punjab including Sargodha, Okara and Faisalabad. Pus
According to Gillespie and Timoney (1981), in
samples were collected in sterilized disposable plastic
strangles the involvement of S. equisimilis was not
syringes and transported in ice packs to the laboratory
significant as equine pathogen, whereas Grant et al.
(1993) concluded that some horses were infected with
both S. equi and S. equisimilis. The incidence of
Bacterial isolation and identification
strangles in young equine population distributed in the
Each pus sample was cultured separately on
thickly populated areas of Punjab has been described in
sodium azide blood agar containing 5% defibrinized
this paper. Moreover, pus samples from strangles
sheep blood and 0.2% sodium azide and incubated at
Pakistan Vet. J., 2008, 28(1): 17-20.
370C for 24 hours under anaerobic conditions. Pure
Antibiotic sensitivity
growth of typical mucoid beta hemolytic colonies were
Streptococcal species were subjected to susceptibility
analyzed through Gram's staining, under microscope
studies against eight antibiotics including Penicillin G,
and were confirmed for streptococcus genus through
Streptomycin, Sulphamethoxazole, Gentamycine,
catalase test. Mucoid, beta hemolytic, and catalase
Chloramphenicol, Cefotoxime, Tetracycline and
negative colonies containing Gram positive cocci were
Ampicillin using standard antibiotic discs and dispenser
declared as pure streptococci and were further (Bioanalyse® France). For this purpose standard processed through API Strep 20 system (Bio Meriux®,
technique elaborated by Cappuccino and Sherman
France) for streptococci species confirmation. (2005) was followed. Biochemical tests including Voges Proskauer test,
Hipurate test, Esculine test, Pyrolidonyl test, Alpha
galactosidae test, Beta glucuronidase test, Beta
galactosidase test, Alkaline phosphates test, Leucine
The incidence of strangles and occurrence of
amino peptidase test, Arginin Dihydrolase test and
streptococcus species in strangles-inflicted foals of 9
fermentation of sugars including D-ribose, L-arabinose,
months to 2 years of age during four seasons around the
D-manitol, D-sorbitol, D-lactose, D-trehalose, Inuline,
year was recorded and it was found to be the highest
D-raffinose, Starch and Glycogen in API strep 20 kit
during spring season (Mid of January to Start of May).
system were used to confirm the streptococcal species.
Animals from 2 years to 5 years of age showed no
clinical signs in any season of the year (Table 1).
Molecular comparison between indigenous
Out of 70 pus samples, typical Streptococcus
Streptococcus equi and foreign strain CF32
species were recovered from 55 samples (78.57%), 6
M-protein of Streptococcus equi was procured
samples had non-streptococcus isolates (8.57%),
following the standard method of Woolcock (1974) and
whereas 9 samples (12.85%) were declared as sterile
was subjected to Sodium Dodecyl Sulphate Poly
where no growth appeared even after 96 hours. Single
Acrylamide Gel Electrophoresis (SDS-PAGE, Timoney
isolate of S. equi was recovered in 54%, followed by
and Strickland, 1984). Band pattern observed though
mixed isolates of S. equi and S. equisimilis (23%),
SDS-PAGE was compared with that of CF32 strain of
single isolates of S. equisimilis (11%) and single isolate
Streptococcus equi already recovered (Galan and
of S. zooepidemicus (11%, Table 2).
Molecular analysis of M-protein extracted from S. equi revealed a pattern with bands 30 Kda, 41 Kda, 46
Optimization of modified Todd-Hewitt broth
Kda and 60 Kda. An equal count (4x1011/ml) was
Filtered and heat inactivated (560C) horse serum
recorded after 24 hours in test tubes containing
was dispensed in duplicate at a rate of 2, 5 and 10% in
modified Todd-Hewitt broth with 5 and 10% horse
three test tubes containing 10 ml of modified Todd-
serum at 370C. In broth with 2% horse serum, count
Hewitt broth. Fresh culture of S. equi was inoculated in each of three test tubes. These tubes were incubated at
370C and count of streptococcal cells was conducted
Each of the three streptococcal species were
cultured and growth after 24 hours was subjected to
Table 1: Incidence of strangles during January to December 2005 in Punjab, Pakistan Adult horses/mules (2 - 5 years) Young foals (9 months-2 years) (Cases in number) (Cases in million) Pakistan Vet. J., 2008, 28(1): 17-20. Table 2: Streptococcal species isolated from pus samples in strangles cases of foals No. (%) of Hemolytic Esculine Fermentation test Streptococcal isolates character hydrolysis Ribose Trehalose Sorbitol Lactose
eight antibiotic culture sensitivity discs. From the
effective vaccine against strangles. Optimization of
results, it is clear that each of the three recovered
already modified Todd-Hewitt broth was conducted by
streptococcal species was sensitive to Penicillin G and
supplementing the broth with different concentrations
Cefotoxime and showed intermediate behavior against
of horse serum. From the experimentation, it was
streptomycin and Sulphamethoxazole. Streptococcal
concluded that modified Todd-Hewitt broth
species showed resistance against Gentamycine and
supplemented with 5% horse serum is economical and
efficient compared to broth dispensed with 2% and 10%
horse serum for the mass scale growth of S. equi.
DISCUSSION
Antibiotic susceptibility of each of three
streptococcal species revealed that in vitro Penicillin G
A survey for the incidence of strangles in young as
and Cefotoxime were very effective against
well as adult population of equines round the year was
Streptococci. As far as the effects of antibiotics
conducted to get an idea about the season in which this
treatment in strangles is concerned, it is a different story
disease can affect animals and to confirm the age group
because in early stages of infection the use of these
usually inflicted with this disease. Incidence of
antibiotics aborts the reaction and no immunity is
strangles was found highest in foals of 9 months to 2
developed and as treatment is withdrawn, the infection
years of age during spring season (Mid of January to
re-occurs (Harrington et al., 2002). In later stages, lack
of sufficient vascularity at the site of infection and
Out of total samples, 23% streptococcal isolates
abscessation interferes with the antibiotic to combat
contained mixed growth of S. equi and S. equisimili and
six streptococcal isolates (11%) contained S. equisimilis
In the present study, it was seen that incidence of
alone, confirming the fact that horses are infected with
strangles continuously increased from January to April
both S. equi as well as S. equisimilis (Grant et al.,
and then it started decreasing. In July, no new case was
1993). M-proteins of locally isolated S. equi after
reported after the report of few cases in June. Incidence
analysis through SDS-PAGE showed a band pattern similar to that found in S. equi strain CF32 thus
of strangles from the end of January to the start of May
confirming the fact that S. equi is homogenous through
in foals of 9 months to 2 years of age was highest
out the world (Galan and Timoney, 1987).
(2.56%) compared to the adult equines of age from 2 to
From the observations made in this study, it is
5 years, confirming the fact that once an animal is
recommended that both S. equi as well as S. equisimilis
infected with strangles it attains life long immunity
should be considered for the development of a safe and
Table 3: Antibiotic sensitivity of Streptococcal isolates recovered from strangles cases of foals Streptococcal Antibiotic Sensitivity Discs (30 micro grams of antibiotic/disc) Penicillin Streptomycin Sulphamet Gentam- Chloramp- Cefotoxi- Tetracycline Ampicillin hoxazole
S = Sensitive, I = Intermediate, R = Resistant Values in parentheses indicate zone diameter in mm.
Pakistan Vet. J., 2008, 28(1): 17-20. Conclusions
George, J. S., J. S. Reif, R. K. Sheider, C. J. Small, R.
A higher occurrence of S. equi was recorded in
P. Ellis, S. P. Snyder and A. E. McChesney, 1983.
young foals compared to adults. S. equi alone and in
Identification of carriers of Streptococcus equi in a
conjunction with S. equisimilis were isolated in the
naturally infected herd. J. Amer.Vet. Med. Assoc.,
laboratory. The isolates showed maximum sensitivity to
penicillin and cefotoxime. Therefore, it may be
Grant, S. T., A. Efstratiou and N. Chanter, 1993.
recommended to prepare a bivalent vaccine for the
Laboratory diagnosis of strangles and the isolation of atypical Streptococcus equi. Vet. Rec., 133: 215-
Harrington, D. J., I. C. Sutcliffe and N. Chanter, 2002.
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