46
dosed at 1 % for 28 days for the control of lactococcosis in grey mullet ( Mugil
cephalus ). Resistance to experimental challenge was reported to be signifi cantly
enhanced (Choi et al. 2014 ).
Probiotics Lactococcosis, which is often diffi cult to control by other means, has
been receptive to the use of probiotics, with Aer. sobria GC2 (recovered from the
digestive tract of ghost carp) dosed at 5 × 10
7 cells/g of feed and fed over 14 days,
stimulating the innate immune response (increase in leucocytes, phagocytosis, and
respiratory burst activity) and conferring excellent protection against challenge
(Brunt and Austin 2005 ). Leuconostoc mesenteroides and Lactobacillus plantarum,
which were isolated from salmonids, were also effective at controlling lactococcosis when dosed at 10
7 cells/g of feed for 30 days with mortalities reduced from 78 %
in the controls to 46 and 54 % in the experimental groups (Vendrell et al. 2008 ).
When a bacteriocin (Nisin Z) producing Lactococcus lactis subsp. cremoris was
administered orally to rainbow trout at 10
6 CFU/g for 21 days, only 20 % of the fi sh
died (compared to 50 % of a non-bacteriocinogenic knockout isogenic mutant, and
72.5 % of the controls) following challenge with Lactococcus garvieae (Araujo
et al. 2015 ).
Biological Control There are promising signs that bacteriophage may be able to
moderate infections by Lactococcus garvieae in yellowtail (Nakai et al. 1999 ) and
rainbow trout (Ghasemi et al. 2014 ).
Antimicrobial Compounds Resistance to erythromycin, lincomycin and oxytetracycline has been reported among Japanese isolates of Lactococcus garvieae , with
the problem recognised for well over a decade (Kawanishi et al. 2005 ).
Lactococcus lactis subsp. lactis
Characteristics of the Disease
In hybrid sturgeon ( Huso huso x Acipenser ruthenus ) in Taiwan, diseased fi sh were
anorexic, generally pale, with haemorrhagic ulcers on the tail and abdomen, which
was enlarged [with ascites], enteritis, liquefi ed spleen, and rapid respiration, with
100 % mortality (Chen et al. 2012 ). Extensive skin lesions were observed near the
caudal peduncle of an adult silver carp ( Hypophthalmichthys molitrix ) in the
USA. Also, there was a musculoskeletal lesion. The disease was coined lactococcosis (Khoo et al. 2014 ).
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)
dosed at 1 % for 28 days for the control of lactococcosis in grey mullet ( Mugil
cephalus ). Resistance to experimental challenge was reported to be signifi cantly
enhanced (Choi et al. 2014 ).
Probiotics Lactococcosis, which is often diffi cult to control by other means, has
been receptive to the use of probiotics, with Aer. sobria GC2 (recovered from the
digestive tract of ghost carp) dosed at 5 × 10
7 cells/g of feed and fed over 14 days,
stimulating the innate immune response (increase in leucocytes, phagocytosis, and
respiratory burst activity) and conferring excellent protection against challenge
(Brunt and Austin 2005 ). Leuconostoc mesenteroides and Lactobacillus plantarum,
which were isolated from salmonids, were also effective at controlling lactococcosis when dosed at 10
7 cells/g of feed for 30 days with mortalities reduced from 78 %
in the controls to 46 and 54 % in the experimental groups (Vendrell et al. 2008 ).
When a bacteriocin (Nisin Z) producing Lactococcus lactis subsp. cremoris was
administered orally to rainbow trout at 10
6 CFU/g for 21 days, only 20 % of the fi sh
died (compared to 50 % of a non-bacteriocinogenic knockout isogenic mutant, and
72.5 % of the controls) following challenge with Lactococcus garvieae (Araujo
et al. 2015 ).
Biological Control There are promising signs that bacteriophage may be able to
moderate infections by Lactococcus garvieae in yellowtail (Nakai et al. 1999 ) and
rainbow trout (Ghasemi et al. 2014 ).
Antimicrobial Compounds Resistance to erythromycin, lincomycin and oxytetracycline has been reported among Japanese isolates of Lactococcus garvieae , with
the problem recognised for well over a decade (Kawanishi et al. 2005 ).
Lactococcus lactis subsp. lactis
Characteristics of the Disease
In hybrid sturgeon ( Huso huso x Acipenser ruthenus ) in Taiwan, diseased fi sh were
anorexic, generally pale, with haemorrhagic ulcers on the tail and abdomen, which
was enlarged [with ascites], enteritis, liquefi ed spleen, and rapid respiration, with
100 % mortality (Chen et al. 2012 ). Extensive skin lesions were observed near the
caudal peduncle of an adult silver carp ( Hypophthalmichthys molitrix ) in the
USA. Also, there was a musculoskeletal lesion. The disease was coined lactococcosis (Khoo et al. 2014 ).
2 Gram-Positive Bacteria (Anaerobes and ‘Lactic Acid’ Bacteria)