• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.302-307
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• 2003

Although, in human medicine, strains of methicillin-resistant staphylococi have become the most important causative agents of nosocomial infections, studies on the small animals are very. limited. The aim of this study was to determine mecA gene and susceptibility to antibiotics of staphylococci strains isolated from clinically ill or healthy dogs and cats, during the period August 2002-July 2003. A total of 136 staphylococci (87 coagulase-positive and 49 coagulase-negative) were investigated for antibiotic resistance, using disk diffusion and minimum inhibitory concentration (MIC) test. The mecA gene was detected using the polymerase chain reaction. The isolates belonged to the species S. aureus (53 isolates), S. intermedius (34 isolates), S. epidermidis (26 isolates) and other coagulase-negative staphylococci (CNS, 23 isolates). Of the 136 isolates, 43 (31.6%) were mecA-positive and the frequency of the ,presence of mecA gene varied among the different species. All S. aureus strains were mecA-negative and were found to be susceptible, with an oxacillin MIC $\leq$1 $\mu\textrm{g}$/ml. Five (13.6%) isolates of 36 that exhibited oxacillin resistance on the MIC testing were found to be mecA-negative, suggesting not all mecA-positive strains may be an oxacillin resistant. However, the mecA presence of the strains was correlated with high oxacillin resistance: 71.4% (10 isolates of 14; P < 0.001) for mecA-positive S. intermedius and 72.4% (21 isolates of 29; P < 0.001) for mecA-positive CNS isolates. About 69% (94 isolates of 136) showed resistance to at least one drug, and 22.8% (31 isolates) were resistant to four or more different drug classes. Resistance (36 isolates, 71.7%) to penicillin G was a common finidng. This study suggest that the mecA-positive staphylococci are prevalent in small animals, and selection of antibiotics to treat infections caused by mecA-positive staphylococci may be very limited because of multi-drug resistance.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1377-1383
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• 2006

Among 46 Acinetobacter baumannii isolates collected in 2004, two imipenem-resistant isolates were obtained from clinical specimens taken from patients hospitalized in Busan, Republic of Korea. Two carbapenemase-producing isolates were further investigated to determine the mechanism of resistance. These isolates were analyzed by antibiotic susceptibility testing, microbiological tests of carbapenemase activity, determination of pI, transconjugation test, enterobacterial repetitive consensus (ERIC)-PCR, and DNA sequencing. Two cases of infection by A. baumannii producing the IMP-1 ${\beta}$-lactamase were detected. The isolates were characterized by a modified cloverleaf synergy test and EDTA-disk synergy test. Isoelectric focusing of crude bacterial extracts revealed nitrocefin-positive bands with a pI value of 9.0. PCR amplification and characterization of the amplicons by direct sequencing indicated that the isolates carried a $bla_{IMP-l}$ determinant. The isolates were characterized by a multidrug resistance phenotype, including penicillins, extended-spectrum cephalosporins, carbapenems, and aminoglycosides. These results indicate that the observed imipenem resistance of two Korean A. baumannii isolates was due to the spread of an IMP-1-producing clone. Our microbiological test of carbapenemase activity is simple to screen class B metallo-${\beta}$-lactamase-producing clinical isolates to determine their clinical impact and to prevent further spread. This study shows that the $bla_{IMP-l}$ resistance determinant, which is emerging in Korea, may become an emerging therapeutic problem, since clinicians are advised not to use extended-spectrum cephalosporins, imipenem, and aminoglycosides. This observation emphasizes the importance of having effective control measures in Asian hospitals, such as early detection of colonized patients, isolation procedures, and a judicious use of antibiotics.

• Pediatric Infection and Vaccine
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• v.15 no.1
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• pp.45-51
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• 2008

Purpose : Better understanding of the epidemiology of Streptococcus pneumoniae affects preventive and therapeutic strategies for children with otitis media. This study was undertaken to examine the prevalence of pneumococcal serotypes causing otitis media in children. Methods : Pneumococcal isolates obtained from the ear discharge of children with otitis media between January 2001 and December 2006 were characterized by serotyping and antibiotic susceptibility testing. Results : There were 54 pneumococcal isolates from 54 children with otitis media. The median age of patients was 13 months, and the proportion of children <5 years old was 81%. The predominant serotypes, in order of decreasing frequency, were 19A (44%), 19F(28%), 6B (7%), 6A (4%), 9V (4%), and 1 (4%); 23 isolates (43%) belonged to types included in the heptavalent pneumococcal conjugate vaccine (PCV7). The proportion of serotype 19A and 19F accounted for 72% of overall pneumococcal isolates, which accounted for 84% of pneumococcal isolates from otorrhea of children <5 years old (vs 20% in children ${\geq}5$ years old, P<0.001). All serotypes isolated from 3 vaccinees of PCV7 were 19A. There was no significant diminution in otitis media caused by pneumococcal vaccine serotypes after the introduction of PCV7. The frequency of nonsusceptibility to penicillin, erythromycin, and trimethoprim-sulfamethoxazole was higher in serotype 19A than in other non-vaccine serotypes, respectively. The frequency of multiple drug resistance was 96% in serotype 19A, compared with 29% in other non-vaccine serotypes (P=0.001). Conclusion : 19A was the most common pneumococcal serotype causing otitis media and represented a large proportion of strains with multiple drug resistance in children younger than 5 years of age.