ISRAEL JOURNAL OF
VETERINARY MEDICINE
BACTERIOLOGICAL STUDIES ON FOAL
SEPTICEMIA IN TURKEY
Vol. 57 (1) 2002
N.Y. Ozgur
Department of Microbiology, Veterinary Faculty, University of Istanbul,
Avcilar, Istanbul, Turkey
Abstract
Septicemia in Thoroughbred foals in the Marmara region of Turkey was investigated.
Between January 1999 and April 2001, tissues were obtained from 38 foals aged between
1 and 30 days with suspected septicemia on the basis of clinical and necropsy findings,
and one blood sample from a three-day-old live foal were investigated bacteriologically.
Septicemia was confirmed by isolation of bacteria from more than one organ of 27
(71%) dead foals and from the blood culture of the live foal. The remainder were
unconfirmed bacteriologically.
Thirty-five bacterial isolations were made from 27 of 38 dead foals, of which 5 bacterial
species were identified. Seventy-four percent of the isolates were Gram-negative and 26
% were Gram-positive. Bacteria were isolated in pure culture from 19 (70%) of 27 foals
and 8 (30 %) of the cultures were mixed. Escherichia coli, Actinobacillus spp and
Streptococcus equi subs. zooepidemicus were the most frequently isolated in this study
with isolation rates of 56 %, 26 %, and 22 %, respectively. Anaerobic bacteria were not
isolated from any of the dead foals while Clostridium perfringens was isolated from the blood
culture of the live foal.
Introduction
Septicemia is a major cause of death in neonatal foals, and the highest mortality rate
occurs within the first week of life (1,2,3). The most common predisposing factor is failure of
passive transfer of immunoglobulins (4,5,6,7). When passive transfer is adequate, other
factors such as poor hygiene and management can play a role in the developing of
septicemia (8). A foal may become septicemic if it has not received an adequate amount of
antibodies or when it is exposed to large amounts of harmful bacteria. Infections are acquired
either in utero or per os, the respiratory tract or umbilicus during parturition or during the early
neonatal period (3,9). The bacteria reach the bloodstream and the infection can then spread
to other organs such as the lungs, intestinal tract, liver, kidneys and joints (10). Postnatal
infections occur within 48-96 hours of parturition. Infection due to Actinobacillus equuli may
develop in the first 18-24 hours of life (11,12). Foals with in utero acquired infections are born
infected or clinical signs may appear within 24 hours of parturition (10).
Initial signs of septicemia are a weakened suckle reflex, depression, lethargy, increased
respiration rate, diarrhea, and hypothermy or hyperthermy (7,10). However clinical signs are
often subtle and non-specific (1,13). Therefore, early recognition of septicemia is difficult
(2,6,14).
Septicemia is confirmed by bacterial culture from the blood of sick foals and from those
considered to be at high risk or specimens of internal organs obtained at necropsy (15).
Escherichia coli and A. equuli are predominant organisms that cause foal septicemia
(3,15,16). However, these organisms vary from country to country. The incidence of causative
bacterial species in different farms varies with differences in management, climate, using of
different antibiotics, geographic distribution, type and virulence of environmental organisms
(7,10).
The aims of the study were to determine the frequency of isolation of bacteria from
Thoroughbred foals with suspected septicemia in Turkey, to detect predominant organisms
and to compare these findings with the results of studies carried out in other countries.
Materials and Methods
Foals
During the period January 1999 to April 2001, internal organ specimens from dead foals on
some race horse breeding farms in the Marmara region were investigated bacteriologically.
The study included 38 dead foals aged between 1 and 30 days with suspected septicemia on
the basis of clinical and necropsy findings. In addition, blood sample of a 3 day-old live foal
with septicemia that was diagnosed clinically was also cultured. The foal had a weak suckle reflex,
hypothermy (360C), depression, lethargy, weakness and diarrhea. Specimens for isolation of bacteria
were taken from internal organs of foals at necropsy and were cultured immediately.
Culture of internal organs
Each specimen from internal organs of dead foals including lungs, liver, kidney and spleen
was inoculated onto two sheep blood agar and one MacConkey agar plates. Blood agar
plates incubated under both microaerobic (Oxoid Campygen) and anaerobic (Oxoid Anaerogen)
conditions while MacConkey agar plates were incubated aerobically at 37 0C for 7 days. The colonies
were observed macroscopically and were Gram stained.
Culture of blood sample
Ten ml of blood were withdrawn aseptically from the jugular vein of the live foal and placed
in a blood culture bottle (Oxoid Signal Blood Culture System). When bacterial growth was
observed after 24 hours incubation at 370C, Gram staining was performed. The blood culture broth
was subcultured on blood agar plates and incubated aerobically, microaerobically and anaerobically for
24 hours.
Isolated bacteria from live and dead foals were identified using routine biochemical tests
(17).
Results
Septicemia was confirmed by isolation of bacteria from more than one organ of 27 dead
foals but was unconfirmed from 11, and was also confirmed by isolation of bacteria from the
blood of the live foal.
Thirty five bacterial isolations were made from 27 of 38 dead foals, out of which 5 bacterial
species were identified. Seventy four percent of the isolates were Gram-negative and 26 %
were Gram-positive. Bacteria were isolated in pure culture from 19 (70%) of 27 foals while 8
(30%) of the cultures were mixed. Anaerobic bacteria were not isolated from any of the dead
foals.
E.coli and Actinobacillus spp were the most frequently isolated organisms. When considered
together, the isolation rate was 82 %. Other organisms isolated were Streptococcus equi subs.
zooepidemicus, Klebsiella pneumoniae and Staphylococcus aureus, respectively (Table 1).
Eight of 15 E.coli strains were isolated in pure culture and these were isolated from foals of
which two were 3 days old, two were 5 days old, one was 11 days old and three were 30 days
old. A. equuli was isolated in pure culture from two foals that were 3 and 10 days old. E.coli
was also isolated with A. equuli from other three foals. One of these foals was one day old
and others were 2 days old. Both A. suis isolates were obtained in pure culture from two foals
aged 1 and 2 days. Three foals from which K. pneumoniae was isolated in pure culture were
1, 7 and 20 days old. K. pneumoniae was also isolated together with E. coli from one foal that was
6 days old. Three foals from which S. equi subs. zooepidemicus was isolated in pure culture were 3, 5
and 30 days old. S.equi subs. zooepidemicus was isolated from one foal with S. aureus and from two
foals with E. coli, which were 4, 8 and 30 days old, respectively. The foal with S. aureus was 10 days
old and was mixed with E. coli in one 5 days old foal.
Clostridium perfringens was isolated from the blood sample of the live foal.
Table 1: Percentages of bacteria that were isolated from foals with septicemia according to total
isolates and isolation rates.
Bacterial isolates
E.coli
Actinobacillus
spp
Number of
positive
cultures
Percentage of
total isolates
Isolation rates
(%)
15
43
56
A.
equuli
5
A. suis
2
20
14
26
19
6
7
6
17
22
K.pneumoniae
4
11
15
S. aureus
3
9
11
S.
equi
zooepidemicus
subs.
Discussion
Septicemia is an important cause of mortality and it has been reported that 33% of deaths
in Thoroughbred foals up to three months old are due to septicemia (5). The most important
factor which predisposes foals to septicemia is a failure of passive transfer of immunity (5,6,7,18).
Platt (3) has reported 61 cases of foal septicemia in England of which 38 cases were in
foals younger than 2 weeks of age. In the present study, 33 (87%) out of 38 foals and 22
(81%) of 27 foals from which bacteria were isolated were younger than two weeks old. These
results were found to be higher than those of Platt who also reported isolation rates of 47 %
for A. equuli and 44 % for E. coli from dead foals younger than two weeks old. In this study,
A. equuli was isolated from 5 foals all younger than two weeks old. In foals younger than two
weeks old, the isolation rate of A. equuli was 19 % while E.coli was isolated from 41 %.
E. coli was the most frequently isolated organism in this study. A. equuli and Streptococcus spp.
were predominant isolates recovered from septic foals in the studies carried out in the United States
(21) and England (22). Platt (3) and Whitwell (16) in Newmarket, Wilson and Madigan (19) in
California, Brewer and Koterba (20) in Florida have reported that E. coli was more predominant than
A. equuli. Raisis et al. (15) also indicated that E. coli was the predominant organism in Australia. This
study suggests that E. coli is also the predominant organism in foals in Turkey, in line with other
studies (3,15,19).
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