Staphylococcus aureus belongs to the group of major contagious mastitis pathogens, whereas the coagulase-negative staphylococci (CNS) are also capable of causing opportunistic bovine mastitis. Many of these strains are resistant to penicillin or ampicillin because of the long-term use of beta-lactam antibiotics in agricultural and healthcare settings. Based on the simple and highly specific coagulase genotyping by PCR-RFLP used for discriminating among Staph. aureus strains, the relationship between phenotypic antibiogram and the polymorphism of coagulase gene was determined in this study. The staphylococci strains (835 Staph. aureus and 763 CNS) were isolated from 3,047 bovine mastitic milk samples from 153 dairy farms in 8 provinces from 1997 to 2004 in the Republic of Korea. Twenty-one (2.5%) Staph. aureus and 19 (2.4%) CNS strains were resistant to methicillin [oxacillin minimum inhibitory concentration (MIC) > or = 4 microg/mL]. The mecA gene was also found in 13 methicillin-resistant Staph. aureus (MRSA) and 12 methicillin-resistant CNS (MRCNS) isolates with a significantly higher detection rate of the mecA gene in MRSA with high MIC (> or = 16 microg/mL) compared with those with MIC < or = 8 microg/mL. Methicillin-resistant Staph. aureus and MRCNS were also more resistant to other antibiotics (ampicillin, cephalothin, kanamycin, and gentamicin) than methicillin-susceptible staphylococci. Among 10 different coa PCR-RFLP patterns (A to J) in 706 Staph. aureus strains, the main types were A (26.9%), B (17.0%), G (10.5%), and H (15.4%), with the frequent observation of the A and H types (6 and 10 isolates) in MRSA. This study indicates that major epidemic Staph. aureus clones may be spread between different dairy farms, and the profile of coa genotype can be applied for epidemiological investigations and control of bovine mastitis, particularly one caused by MRSA with specific prevalent coa types.

Intramuscular fat (IMF) content in skeletal muscle including the longissimus dorsi muscle (LM), also known as marbling fat, is one of the most important factors determining beef quality in several countries including Korea, Japan, Australia, and the United States. Genetics and breed, management, and nutrition affect IMF deposition. Japanese Black cattle breed has the highest IMF content in the world, and Korean cattle (also called Hanwoo) the second highest. Here, we review results of research on genetic factors (breed and sex differences and heritability) that affect IMF deposition. Cattle management factors are also important for IMF deposition. Castration of bulls increases IMF deposition in most cattle breeds. The effects of several management factors, including weaning age, castration, slaughter weight and age, and environmental conditions on IMF deposition are also reviewed. Nutritional factors, including fat metabolism, digestion and absorption of feed, glucose/starch availability, and vitamin A, D, and C levels are important for IMF deposition. Manipulating IMF deposition through developmental programming via metabolic imprinting is a recently proposed nutritional method to change potential IMF deposition during the fetal and neonatal periods in rodents and domestic animals. Application of fetal nutritional programming to increase IMF deposition of progeny in later life is reviewed. The coordination of several factors affects IMF deposition. Thus, a combination of several strategies may be needed to manipulate IMF deposition, depending on the consumer’s beef preference. In particular, stage-specific feeding programs with concentrate-based diets developed by Japan and Korea are described in this article.

In Korea, Mycoplasma pneumoniae was detected in 255/2,089 respiratory specimens collected during 2000–2011; 80 isolates carried 23S rRNA gene mutations, and 69/123 culture-positive samples with the mutation were resistant to 5 macrolides. During 2000–2011, prevalence of the mutation increased substantially. These findings have critical implications for the treatment of children with mycoplasma pneumonia.

Highly pathogenic avian influenza viruses (HPAIV) of the H5N1 subtype have spread since 2003 in poultry and wild birds in Asia, Europe and Africa. In Korea, the highly pathogenic H5N1 avian influenza outbreaks took place in 2003/2004, 2006/2007 and 2008. As the 2006/2007 isolates differ phylogenetically from the 2003/2004 isolates, we assessed the clinical responses of chickens, ducks and quails to intranasal inoculation of the 2006/2007 index case virus, A/chicken/Korea/IS/06. All the chickens and quails died on 3 days and 3-6 days post-inoculation (DPI), respectively, whilst the ducks only showed signs of mild depression. The uninoculated chickens and quails placed soon after with the inoculated flock died on 5.3 and 7.5 DPI, respectively. Both oropharyngeal and cloacal swabs were taken for all three species during various time intervals after inoculation. It was found that oropharyngeal swabs showed higher viral titers than in cloacal swabs applicable to all three avian species. The chickens and quails shed the virus until they died (up to 3 to 6 days after inoculation, respectively) whilst the ducks shed the virus on 2-4 DPI. The postmortem tissues collected from the chickens and quails on day 3 and days 4-5 and from clinically normal ducks that were euthanized on day 4 contained the virus. However, the ducks had significantly lower viral titers than the chickens or quails. Thus, the three avian species varied significantly in their clinical signs, mortality, tissue virus titers, and duration of virus shedding. Our observations suggest that duck and quail farms should be monitored particularly closely for the presence of HPAIV so that further virus transmission to other avian or mammalian hosts can be prevented.

The aim of this study was to determine the antimicrobial resistance of various species of enterococci isolated from mastitic bovine milk samples. A total of 105 enterococci isolates were examined: Enterococcus faecalis (n = 47), Enterococcus faecium (n = 39), Enterococcus gallinarum (n = 6), Enterococcus avium (n = 6), Enterococcus hirae (n = 5) and Enterococcus durans (n = 2). All the isolates were susceptible to ampicillin, gentamicin and vancomycin, and only a single E. hirae isolate was resistant to ampicillin. In general, the most frequently observed resistance among the enterococcal isolates was to tetracycline (69.5%), followed by penicillin (64.7%), erythromycin (57.1%) and cephalothin (44.7%). A similar antimicrobial resistance pattern was observed among individual species except E. durans, which exhibited only tetracycline resistance. Resistance observed among isolates of E. hirae and E. gallinarum was almost as high as E. faecium and E. faecalis. Of 105 isolates, only six (5.7%) strains of E. faecium were susceptible to all the antimicrobials tested and about 52% (55/105) showed resistance to more than three antimicrobials. The most common multiple resistance pattern was penicillin, tetracycline and erythromycin, which was observed in 32 of 105 (30.4%) isolates. This study demonstrates that enterococcal isolates belonging to minor species showed antimicrobial resistance rates as high as those of E. faecium and E. faecalis, and that monitoring of antimicrobial resistance should not be restricted only to those two major species.