In Vitro Activities of Daptomycin Against Recent Clinical Isolates of Methicillin-resistant Staphylococci and Vancomycin-resistant Enterococci in Korea / 감염과화학요법

BACKGROUND: Daptomycin is a novel cyclic lipopeptide antibiotic that exhibits in vitro bactericidal activity against gram-positive pathogens including methicillin-resistant staphylococci and vancomycin-resistant enterococci. The aim of this study is to determine the in vitro activities of daptomycin against recent clinical isolates of methicillin-resistant staphylococci and vancomycin-resistant enterococci in Korea. MATERIALS AND METHODS: A total of 117 clinical strains of methicillin-resistant staphylococci and vancomycin-resistant enterococci were isolated at a tertiary-care hospital in Korea in 2004. Susceptibility to daptomycin was tested by the CLSI broth microdilution method using Mueller-Hinton broth (MHB) which was adjusted to contain a final concentration of 50 microgram/mL of ionized calcium (Ca2+). Susceptibilities to ampicillin, oxacillin, levofloxacin, vancomycin, and linezolid were tested by the CLSI agar dilution method. RESULTS: All isolates of methicillin-resistant S. aureus and coagulase-negative staphylococci were inhibited by 1 microgram/mL of daptomycin, and MIC90s were 1 microgram/mL, which were similar to those of vancomycin and linezolid. MIC90s of daptomycin for vancomycin-resistant E. faecalis and E. faecium were 0.5 microgram/mL and 2 microgram/mL, respectively, and all isolates were susceptible to daptomycin. MIC90s of linezolid and levofloxacin for vancomycin-resistant enterococci were 1-2 microgram/mL and 64 microgram/mL, respectively. Resistance rates of vancomycin-resistant E. faecalis and E. faecium to levofloxacin were 100% and 96%, respectively. Daptomycin MICs in MHB supplemented to 20-25 microgram/ml of Ca2+ were 2-8 fold higher than those in MHB supplemented to 50 microgram/mL of Ca2+. CONCLUSION: Daptomycin is very active in vitro against methicillin-resistant staphylococci and vancomycin-resistant enterococci isolated in Korea, and it is important to test in vitro activity of daptomycin using MHB containing 50 microgram/mL of Ca2+.

In Vitro Activities of Daptomycin Against Recent Clinical Isolates of Methicillin-resistant Staphylococci and Vancomycin-resistant Enterococci in Korea / 감염과화학요법

BACKGROUND: Daptomycin is a novel cyclic lipopeptide antibiotic that exhibits in vitro bactericidal activity against gram-positive pathogens including methicillin-resistant staphylococci and vancomycin-resistant enterococci. The aim of this study is to determine the in vitro activities of daptomycin against recent clinical isolates of methicillin-resistant staphylococci and vancomycin-resistant enterococci in Korea. MATERIALS AND METHODS: A total of 117 clinical strains of methicillin-resistant staphylococci and vancomycin-resistant enterococci were isolated at a tertiary-care hospital in Korea in 2004. Susceptibility to daptomycin was tested by the CLSI broth microdilution method using Mueller-Hinton broth (MHB) which was adjusted to contain a final concentration of 50 microgram/mL of ionized calcium (Ca2+). Susceptibilities to ampicillin, oxacillin, levofloxacin, vancomycin, and linezolid were tested by the CLSI agar dilution method. RESULTS: All isolates of methicillin-resistant S. aureus and coagulase-negative staphylococci were inhibited by 1 microgram/mL of daptomycin, and MIC90s were 1 microgram/mL, which were similar to those of vancomycin and linezolid. MIC90s of daptomycin for vancomycin-resistant E. faecalis and E. faecium were 0.5 microgram/mL and 2 microgram/mL, respectively, and all isolates were susceptible to daptomycin. MIC90s of linezolid and levofloxacin for vancomycin-resistant enterococci were 1-2 microgram/mL and 64 microgram/mL, respectively. Resistance rates of vancomycin-resistant E. faecalis and E. faecium to levofloxacin were 100% and 96%, respectively. Daptomycin MICs in MHB supplemented to 20-25 microgram/ml of Ca2+ were 2-8 fold higher than those in MHB supplemented to 50 microgram/mL of Ca2+. CONCLUSION: Daptomycin is very active in vitro against methicillin-resistant staphylococci and vancomycin-resistant enterococci isolated in Korea, and it is important to test in vitro activity of daptomycin using MHB containing 50 microgram/mL of Ca2+.

Korean Nationwide Surveillance of Antimicrobial Resistance in 2000 with Special Reference to Vancomycin Resistance in Enterococci, and Expanded-Spectrum Cephalosporin and Imipenem Resistance in Gram-Negative Bacilli

Antimicrobial resistance surveillance is necessary to determine the size of the problem and to guide empirical selection of antimicrobial agents for treating infected patients. The aim of this study was to analyze the results of susceptibility tests performed by hospitals participating in the Korean Nationwide Surveillance of Antimicrobial Resistance (KONSAR) program. The rates of oxacillin-resistant staphylococci, penicillin-nonsusceptible pneumococci, and ampicillin-resistant E. faecium were over 70%. Ampicillin-resistant H. influenzae increased to 68%. Expanded-spectrum cephalosporin-resistant K. pneumoniae, fluoroquinolone-resistant E. coli, and imipenem-resistant P. aeruginosa remained at 16% through 27%, depending on the species. The proportions of vancomycin-resistant E. faecium and imipenem-resistant P. aeruginosa were 18 - 24% and 19-21%, respectively, indicating the seriousness of antimicrobial resistance. In conclusion, the increasing prevalence of resistant bacteria indicates that more concerted effort is required to conserve the usefulness of precious new antimicrobial agents.

Effect of Coexistence of Antimicrobial-susceptible Gram-negative Bacilli on the Resistant Gram-negative Bacilliin the Absence of Antimicrobial Agents / 감염

BACKGROUND: Carrying antimicrobial resistance genes is a burden to bacteria. Therefore, in the absence of antimicrobial selective pressure, susceptible bacteria are expected to replace resistant ones. The cost was reported to decrease with time, but the effect of different species of susceptible bacteria on extended-spectrum -lactamase (ESBL)-, AmpC beta-lactamase-, and VIM-2 metallo-beta-lactamase-producing gram-negative bacilli are not known. The aim of this study was to determine the effect in vitro. METHODS: Antimicrobial-susceptible and -resistant strains of Escherichia coli, Enterobacter aerogenes, Klebsiella p neumoniae, and Acinetobacter baumannii were subcultured daily in glucose limited minimal salt medium at 30degrees C and 37degrees C, and the numbers of cells (CFU/mL) were determined by culturing on Mueller-Hinton agar and MacConkey agar plates. RESULTS: Continued incubation without subculture of both individual and mixed cultures at 37degrees C showed higher counts of a ESBL-producing K. p neumoniae than a susceptible E. coli. Daily subcultures of two strains in a tube showed the counts were : ESBL-producing K. pneumoniae >susceptible E. coli; susceptible E. aerogenes >ESBL-producing K. p neumoniae; susceptible E. aerogenes >VIM-2-beta-lactamase-producing Acinetobacter baumannii. The counts were similar for susceptible K. p neumoniae and AmpC beta-lactamasehyperproducing E. aerogenes. Initial low count of a susceptible E. coli and an ESBL-producing K. p neumoniae at 30degrees C gradually increased with continued subculture. CONCLUSION: Growth of not all resistant bacteria are slower and the growth improves with continued subculture. Coexistence of a susceptible bacteria with resistant bacteria in GLMS medium both at 30degrees C and 37degrees C does not reduce the number of resistant bacteria.

Isolation Trend of Enterobacter, Citrobacter, and Serratia for the Recent Five Years and Antimicrobial Susceptibility of Derepressed AmpC beta-lactamase Producing Strains / 감염

BACKGROUND: Derepressed AmpC beta-lactamase producing Enterobacter cloacae, Citrobacter f reundii, and Serratia marcescens are important nosocomial pathogens and the infections are difficult to treat, because they are multi-drug resistant. The aim of this study was to determine the isolation rate and trend, and antimicrobial susceptibility of derepressed strains isolated from clinical specimens. METHODS: E. cloacae, S. marcescens, and C. f reundii isolated from 1996 through 2000 were enrolled in the study. Antimicrobial susceptibility was tested by NCCLS disk diffusion method. Derepressed strain was defined as strain non-susceptible to third generation cephalosporin. The isolation patterns of important gram-negative bacilli with the derepressed strains were analyzed with respect to years, patient's locations and specimens. RESULTS: Among the clinical isolates, the derepressed strains of E. cloacae, S. marcescens, and C. f reundii were 65%, 70%, and 56%. The proportion of the derepressed strains : E. cloacae increased from 68% in 1996 to 71% in 1998, however, decreased to 59% in 2000, S. marcescens increased from 68% in 1996 to 73% in 2000, C. f reundii decreased from 69% in 1996 to 41% in 2000. The proportion of the derepressed strains were high among the isolates from blood and respiratory specimens of inpatient and intensive care patient. The resistance rates of the depressed strains were 47~62% to third generation cephalosporin and aztreonam, 15~85% to aminoglycoside, 68% to cotrimoxazole, and 31% to levofloxacin. CONCLUSION: Among the clinical isolates of E. cloacae, S. marcescens, and C. f reundii, the derepressed strains were as high as 56~70%, and they were commonly isolated from blood and sputum specimens of inpatient and intensive care patient, and showed high resistance rates to the most antimicrobial agents.

Antimicrobial Resistance Surveillance of Bacteria in 1999 in Korea with a Special Reference to Resistance of Enterococci to Vancomycin and Gram-Negative Bacilli to Third Generation Cephalosporin, Imipenem, and Fluoroquinolone

The trend of antimicrobial resistance of bacteria isolated from patients in 30 Korean hospitals in 1999 was analyzed with a particular attention to cefotaxime- or fluoroquinolone-resistant gram-negative bacilli, imipenem-resistant Pseudomonas aeruginosa, and vancomycin-resistant enterococci. Adequacy of susceptibility testing, and any change in the frequencies of isolated species were also analyzed. The results showed that only 20% and 30% of hospitals tested the piperacillin-tazobactam and cefoxitin susceptibility of Enterobacteriaceae, respectively, only 24% of hospitals the piperacillin-tazobactam susceptibility of P. aeruginosa, and 17% of hospitals the fusidic acid susceptibility of staphylococci. Among the isolates 26.3% were glucose-nonfermenting gram-negative bacilli, and 34.7% of Enterococcus were Enterococcus faecium. Slight decline of cefotaxime-resistance rate to 20% was noted in Klebsiella pneumoniae, while fluoroquinolone-resistantce rate was 68% in Acinetobacter baumannii. The ceftazidime- and imipenem-resistance rates were 17% and 18%, respectively in P. aeruginosa. The vancomycin-resistance rate of E. faecium rose significantly to 15.1%, but the rates varied significantly depending on hospitals suggesting presence of different degree of selective pressure or nosocomial spread. In conclusion, the prevalence of imipenem-resistant P. aeruginosa and the increase of vancomycin-resistant E. faecium were the particularly worrisome phenomena observed in this study.

Detection of Vancomycin Heteroresistant Staphylococcus aureus Using Mu-3 Agar / 감염

BACKGROUND: The aim of the study was to determine prevalence of potential heterogeneous vancomycin-resistant Staphylococcus aureus (h-VRSA) among methicillin-resistant S. aureus (MRSA) isolated in Korea by using Mu-3 agar and to determine the effect of in vitro vancomycin exposure on the resistance. METHODS: MRSAs isolated in 1980-1999 were screened for the presence of VISA or h-VRSA using Mu-3 agar. MIC of vancomycin was tested by NCCLS agar dilution and broth microdilution tests. Suspected h-VRSA were selected by vancomycin-containing media and change of resistance was determined by population analysis. A strain with Mu50 type growth was serially exposed to 8 pg/ml of vancomycin containing media and change of the vancomycin resistance was determined. RESULTS: Among the 455 MRSA isolates, 18 (3.9 %) grew on selective brain heart infusion agar (BHIA), and 354 (77,8%) on Mu-3 agar, 66 (14.5%) with Mu3 type growth and 78 (17.1%) with Mu50 type growth. MIC of vancomycin was 11 pg/ml for some of the isolates when inocula were approximately 10' CFU, but VISA was not present when tested by NCCLS broth microdilution test. Exposure of the isolates to van-cornycin raised the MIC. Serial exposure once to 8 pg/ml of vancomycin resulted in significant decrease of cells susceptible to 8-12 pg/ml of vancomycin. CONCLUSION: VISA was not present among the test isolates, but 34.2% were suspected to be potential h-VRSAs, suggesting possible emergence of VISA if vancomycin was administered prolonged period. It is considered that suitable screening media are vancomycin containing BHIA for VISA and Mu-3 agar for h-VRSA. The isolates showing Mu50 type growth on Mu-3 agar are not always VISA, but rather h-VRSA.

Current Status of Antimicrobial Resistance in Korea

No Abstract Available.

Current Status of Antimicrobial Resistance in Korea

No Abstract Available.

A Case of Nocardiosis in Patient with Chronic Lymphocytic Leukemia / 대한혈액학회지

Nocardiosis is an acute, subacute, or chronic infection, most often beginning in the lung, and usually affects the immunocompromised host. Nocardial infections are not rare in the United States, 500 to 1000 cases are recognized each year, but rarely reported in Korea. Disorders associated with cellular immune dysfunction are the major risk factors for nocardiosis. We report one case of brain and retroperitoneal abscess caused by Nocardia asteroides in patient who has had a chronic lymphocytic leukemia and diabetes mellitus, with a review of the relevant literature.

Clinical Microbiology in the Era of Cost Saving / 대한임상미생물학회지

No abstract available.

Determination of DNA-DNA Hybridization Condition for Rapid Identification of Mycobacterium Species

Rapid identification of Mycobacterium spp. isolated from patients is important with increased isolation of mycobacteria other than tubercle bacilli (MOTT). DNA-DNA hybridization with streptavidin-peroxidase and tetramethylbenzidine (TMB) color reaction method was recognized as a useful tool for identification of various species of mycobacteria. In this study, optimum condition of the test was determined. The optimal concentrations of tetramethylbenzidine dihydrochloride and hydrogen peroxide for streptavidin-horseradish peroxidase were 0.3-0.6 ug/ ml and 0.16 mM, respectively. The TMB stock solution was stable when prepared in methanol and the dilution of TBM stock solution in 10 mM sodium citrate-10 mM EDTA solution (pH 5.0) gave highest peroxidase-TMB activity. The suitable composition of hybridization solution consisted of 2 x SSC, 10% dextran sulfate, 50 ug/ml salmon DNA, 5 x Denhardt's solution, and 50% formamide. The 5-minute heating at 100C of test DNA prior to photobiotin labeling significantly increased the reaction. In conclusion, DNA-DNA hybridization method with streptavidin-peroxidase and TMB color reaction method may be useful for rapid identification of Mycobacterium spp. isolated from patients.

A Study of Group B Streptococcal Infection in Korean Pregnant Women / 대한산부인과학회잡지

OBJECTIVE: To evaluate the degree of streptococcal colonization in Korean pregnant women. METHODS: The study comprised of 153 singleton pregnant women who visited Severance Hospital for delivery, and their neonates. Specimens for GBS culture were collected by a sterile cotton swab from lower vagina and cervix of pregnant women, and from ear canal and throat of neonates. They were first cultured for 48 hours in Todd-Hewitt broth and then subcultured onto Tryptose blood agar plates(Difco). Group B streptococci were confirmed by the presence of beta-hemolysis and a positive reaction with Phadebact group B Streptococci reagent(Karo Biodiagnostics AB, Huddinge, Sweden). RESULTS: The prevalence of positive cultures in pregnant women and neonates were 2.61%(4/153) and 0%(0/4), respectively. In the study population there was a case of suspicious group B streptococcual sepsis in an infant whose mother was colonized. CONCLUSIONS: In our study the GBS colonization rate in Korean pregnant women was significantly lower than that of other countries. The reason for this difference may be associated with a racial differences, or social factors such as socio-economic status or a life style.

In Vitro Activities of Cefatrizine/clavulanic Acid Against Major Clinical Isolates of Bacteria / 대한임상미생물학회지

BACKGROUND: beta-lactam antibiotics are one of the most frequently used antimicrobial agents. However, with the increase of beta-lactamase-producing bacteria, penicillins arid 1 st generation cephalosporins have become less useful. Cefatrizine and clavulanic acid combination (CTCA) was developed to restore the activity. The aim of this study was to determine the activities of CTCA against major recent clinical isolates. METHODS: Aerobic and anaerobic bacteria tested were isolated from clinical specimens in Severance Hospital during 1996 to 1999. Antimicrobial susceptibility was determined by the NCCLS agar dilution methods. RESULTS: MICs of cefatrizine (CT) and CTCA were similar for methicillin-susceptible Staphylococcus aureus, Streptococcus pyogenes and S. pneumoniae. For Moraxella (Branhamella) catarrhalis, MIC90 CTCA was 1 microgram/mL, which was 1/8-fold lower than that of cefatrizine. MIC90S of CTCA for Escherichia coli and Klebsiella pneumoniae were 4 microgram/mL and 8 microgram/mL, respectively, which were 1/4- to 1/16-fold lower than those of CT. However, it was less active against Citrobacter freundii, Enterobacter cloacae and Serratia marcescens. Against Bacteroides fragilis group organisms, it showed good activities similar to those of other beta-lactam and beta-lactamase inhibitor combinations. CONCLUSIONS: CTCA showed good antimicrobial activities against M. (B.) catarrhalis, Haemophilus influenzae, Neisseria gonorrhoeae, extended spectrum beta-lactamase-producing E. coli and K. pneumoniae, Proteus vulgaris and B. fragilis. In conclusion, it would be useful for the treatment of infections due to those organisms, and for the empirical treatment of respiratory and urinary tract infections.

Group B Streptococcus Isolated from Bacteremic Patients: Serotypes and Antimicrobial Susceptibilities / 대한임상미생물학회지

Group B Streptococcus (GBS, S. agalactiae) is known to be the leading cause of neonatal sepsis and meningitis and the infection has been increasingly noted in adults, particularly in those with underlying diseases. Penicillin G is the drug of choice for GBS infection. However, the MIC of penicillin for GBS is greater than that for S. pyogenes. Therefore some GBS infections may be difficult to be treated. However, in Korea, our knowledge on GBS infection is limited. We observed 7 cases of GBS bacteremia during 1993-1996 in a hospital, Of the 7 patients, 3 were less than one month of age with no known underlying disease and 4 were adults with liver cirrhosis or malignancy. One adult patient developed disseminated intravascular coagulopathy and expired. Among the GBS isolates, 4 were serotype III and 3 were Ib. All of the isolates were susceptible to ampicillin, teicoplanin and vancomycin, but most were intermediate or resistant to clindamycin, erythromycin or tetracycline. It is concluded that GBS also cause severe infections in adult with underlying diseases and the serotypes III and I b may be more virulent than other serotypes. Early detection and antimicrobial susceptibility test of GBS from severe infection may be necessary for the proper treatment of the patients.

A Case of Tularemia Caused by Francisella Tularensis / 대한임상병리학회지

Tularemia is a major laboratory acquired zoonoses caused by Francisella tularensis that have high virulence, and usually transmitted to humans from direct contact with infected wild animals like rabbits or insect vectors like ticks. Clinical tularemia can be divided with 6 major syndromes that are delineated by the mode of organism aquisition, in which ulceroglandular type is the most common. F. tularensis have 3 different biogroups which have homogeneous antigenecity, type A (biogroup tularensis), type B (biogroup palearctica) and biogroup novicida, and can be confirmed by serology most frequently. In the domestic area, there was no reports of tularemia in humans or presence of bacteria in the reservoirs. Authers experienced a case of tularemia which is suspected as F. tularensis type B, ulceroglandular type. A healthy 40-year-old man admitted the hospital for lymph node swelling in both axillary and upper arm area and for furuncles in both forearm and palm. He contacted with dead rabbit and eated it after cooking before 20 days from admission day. In laboratory cultures, F. tularensis did not grow in any of the routine or anaerobic culture media except for one blood agar plate at 5 days. After subculturing that to cystine containing chocolate agar plate at 37C degree, 5% CO2 incubator, we could see the accelerating growth of colony. In microbiological test, it was oxidase and urease negative. In acid production in cystine trypticase agar base, it was glucose positive and sucrose, maltose, glycerol negative. In agglutinating test, F. tularensis antiserum titer (Difco, USA) with isolates was 1:160 or over and antibody titer to F. tularensis antigen (Difco, USA) was 1:320 or over. Anti-F. tularensis-IF assay and Anti-F. tularensis-indirect-EIA with isolates were positive.

Sensitivity and Specificity of Vi-Indirect Fluore scent Antibody Test in Diagnosis of Typhoid Fever / 감염

BACKGROUND: Typhoid fever is diagnosed by culture or serological study. The confirmative diagnosis of typhoid fever is made by culture of the causative orga-nism usually from body fluids. Serological test is a supportive diagnostic tool, which is useful for early dia-gnosis. In Severance Hospital, Vi-indirect fluorescent antibody test(Vi-IFAT) using the Vi-antigen of Salmo-nella typhi has been used in the diagnosis of typhoid fever since 1989. We investigated the test results from the past 7 years, in order to clarify the sensitivity and specificity of Vi-IFAT. METHODS: A retrospective study was done on pa-tients whose chief complaint was fever and who were tested using Vi-IFAT in the Severance Hospital from 1989 to 1996. The positive value for Vi-IFAT was de- fined as 1:64 or higher. RESULTS: The sensitivity and specificity of Vi-IFAT for typhoid fever was 94.4% and 95.1%, respectively. The positive and negative predictive values were 85.7% and 98.2% respectively. Positive rates of Vi-IFAT after fever onset increased with time and 68% were positive before the first week. From the first to the second week, 89.5% were positive and after the second week, 100% were positive. CONCLUSION: Vi-IFAT is not only a valuable sero-logic test for the diagnosis of typhoid fever, but also useful in the early diagnosis of the disease.

Rapid Identification of Methicillin-Resistant Staphylococcus mecA Gene by Polymerase Chain Reaction and Cloning of the Gene

The peneicillin binding protein gene(mecA gene) is present in the methicillin-resistant Staphylococcus strains but not in the susceptible ones. The goal of the present study was to establish experimental evidences which might use polymerase chain reaction(PCR) for culture confirmation and eventually clinical diagnosis of methicillin resistant Staphylococcui. Two primers (5'-AAAATCGATGGTAAAGGTTGGC-3', 5'-AGTTCTGCAGTACCGGATTTGC-3') based on the known DNA sequence of the mecA gene from methicillin-resistant Staphylococcus aureus were used in PCRs to screen for the presence of this gene in Staphylococcal isolates from various clinical settings. When the primers were used to copy the DNA of the mecA gene, only 533 base-pair DNA fragment was appeared. The product indicates a positive PCR result for methicillin-resistant Staphylococcal isolates. In contrast, from the DNA of the methicillin-sensitive Staphylococcal isolates the 533bp was not amplified. Results obtained with PCR were generally consistent with those of standard microbiological assays. The mecA gene in methicillin-high resistant Staphylococci was located on the approximately 5.56kb Hind III restriction fragment. The 533bp probe was hybridized to the 5.56kb Hind III restriction fragment of mecA-positive S. aureus. No hybridization was occured in the mecA-negative strain. The mecA gene was cloned, named pHL-1201 and verified by colony hyhridization. The 533bp probe was hybridized to the approximately 5.56kb Hind III restriction fragment of the DNA obtained from pHL-1201. PCRs with the primers successfully distinguished methicillin-resistants from methicillin-susceptible strains of S. aureus and S. epidermidis.

Detection of Mycobacterium tuberculosis Antigens in Sputum for the Diagnosis of Pulmonary Tuberculosis

As an effort to develop a rapid and sensitive diagnostic test, we produced previously a monoclonal antibody (MAb) specific to the lipoarabinomannan (LAM) antigen and used in a sandwich ELISA for detection of mycobacterial antigens in sputum. In this study, we attempted to improve the antigen detection assay by combination of af5nity-purified antibodies against Mycobacterium tuberculosis soluble antigen and anti-LAM MAb. With the new assay, the LAM antigen was detectable as low as 2 ng/ml, and none of 10 gram-negative and gram-positive organisms gave significant absorbance, thus indicating the specific detection of mycobacterial antigens. Sputum samples from 62 patients who were suspected having tuberculosis and from 37 healthy controls were examined. The sensitivity of the antigen detection assay ranged from 0% in the 1+ culture group to 78.8% in the 3+ culture group. When the results were combined, 15 of 24 culture-positive samples were antigen-positive, thus giving an overall sensitivity of 62.5%. The overall specificity was 96.0%, when all the culture-negative samples were combined. The results thus demonstrate that the antigen detection assay can provide a rapid supplemental information for the diagnosis of pulmonary diagnosis.

Prevalence of antibodies to the coxiella burnetii phase II antigen among residents in korea

No abstract available.