Analysis of Serological Distribution,Virulence Gene and Drug Resistance among Group B Streptococcus from Shenzhen Patients / 现代检验医学杂志

Objective To understand the antimicrobial susceptibility profiles,serotype distribution and virulence genes.Methods A total of 515 group B Streptococcus (GBS) including 108 virulence,112 non virulence,and 295 colonizing isolates were collected in four Shenzhen hospitals.Isolates were characterized by conventional and molecular serotyping.The virulence genes of scpB,lmb,hylB,cylE,bac,bca and rib of GBS isolates were detected by PCR.Antimicrobial susceptibility to penicillins,macrolides,lincosamides,quinolones and tetracyclines was tested using disk diffusion and the MICs for penicillin were determined by E test.Results Molecular serotyping for all eight serotypes (Ⅰa,Ⅰb,Ⅱ ～ Ⅵ,Ⅸ) was in full accordance with conventional serotyping.Taking MS and CS together,serotype Ⅲ was the most common capsular type (56.5 ％),followed by Ⅰb (17.5 ％),Ⅰa (12.6 ％),V (7.4 ％),Ⅱ (2.7 ％),Ⅵ (1.4 ％),Ⅳ (1.0 ％) and Ⅸ (1.0 ％).Serotype Ⅲ was the main serotype in different groups,serotype Ⅰ a was significantly more common among patients with invasive infections (11.1％) and no invasive infections (29.5％),serotype Ⅰb isolates were significantly more common among clone (19.3％).Virulence gene screening using PCR method showed the presence of cylE,lmb,scpB and hylB in almost all the isolates,while rib,bca and bac genes were found in 29.1％,14.6％ and 9.7％ of the isolates.Certain genes were significantly associated with specific serotypes,for example,rib with serotypes Ⅲ,Ⅰa and Ⅰb,bca and bac with serotypes Ⅲ and Ⅰb.Drug susceptibility results showed that GBS susceptibility to β lactam antimicrobials was prevalent (100 ％).Resistance rates for erythromycin,clindamycin and tetracycline were 67.0 ％,61.9 ％ and 86.0 ％,respectively.Conclusion Serotype distribution,virulence genes and antimicrobial susceptibility profiles of GBS contributes to the clinical therapy,epidemiological studies and design of Vaccines.

Group B Streptococcus Infection in Vaginal Tract of Perinatal Pregnant Women and Drug Resistance Analysis / 现代检验医学杂志

Objective To provide evidences which are for clinicians to formulate effective prevention and treatment measures by analyzing the perinatal pregnant women vaginal group B streptococcus (GBS)infection and adverse pregnancy outcomes. Methods From January 2013 to February 2015,the vaginal secretions were sampled from 795 cases of perinatal pregnant women for culture identification of GBS,the final results were statistical analyzed.Results In the 795 pregnant women ca-ses,there were 256 GBS carriers cases,the carrier rate was 32.2%.There was statistically significance (χ2 = 19.095,P <0.01)between less than 30 years old group (28.9%)and greater than or equal to 30 years old group (42.3%).The differ-ent incidence rate of clinical symptoms between GBS negative cases and GBS positive cases (18.8% vs 8.0%)was also had statistically significance (χ2 =39.514,P <0.01).The antimicrobial resistant rates of ten kinds of antibacterial drugs (vanco-mycin,linezolid,penicillin,ampicillin,ceftriaxone,nitrofurantoin,levofloxacin,clindamycin,erythromycin and tetracycline) was 0,0,0.6%,3.1%,6.6%,9.6%,21.9%,23.8%,29.9% and 58.1% respectively.The positive rate of D-bacteriostatic ring experiment was 23.9%.Conclusion The carrier rate of perinatal pregnant women GBS was higher in this region,and the elderly were easier to be infected.Perinatal pregnant women infected with GBS to vancomycin and rina thiazole amine and penicillin and ampicillin and ceftriaxone and with nitrofurantoin because of the sensitive rate is high.

Analysis for Group B Streptococci Isolated from Bacteremic Patients / 대한임상미생물학회지

BACKGROUND: Group B streptococci (GBS) is known to be major cause of neonatal meningitis and bacteremia, and the infections also has been increasing in adults, particularly those with serious underlying diseases. This study is designed to define the trend of infection rate by year, underlying conditions, clinical outcome of group B streptococcal bacteremia, and to compare the distribution of age, sex, and serotype and antimicrobial susceptibility between invasive and noninvasive GBS infections. METHODS: We analyzed the medical records of 36 cases with group B streptococcal bacteremia between 1990 and 2003, and compared the distribution of age, sex, serotype and antimicrobial susceptibility between invasive and noninvasive GBS infections with GBS strains stocked from 1990 to 2000 at Wonju Christian Hospital. RESULTS: Of 36 GBS bacteremia patients, four (11.1%) patients were early-onset neonatal infection, 9 (25.0%) were late-onset neonatal infection, and 23 (63.9%) were older than 30 years of age. In the 23 adult patients, 19 (82.6%) patients had one or more underlying diseases, and liver cirrhosis and diabetes mellitus were the most common underlying diseases. There is no significant difference of antimicrobial susceptibility and serotype distribution of GBS between invasive and noninvasive infections. CONCLUSION: Bacteremia caused by GBS were prevalent in adult patients with chronic underlying diseases. In neonate, late-onset bacteremia was more common than early-onset bacteremia.

Antimicrobial Resistance and Serotypes in the Clinical Isolates of Group B Streptococci / 대한임상미생물학회지

BACKGROUND: This study is designed to provide data on the trend of resistance by year of isolation in the clinical isolates of group B streptococci(GBS) during recent eight years and to elucidate the relationship between serotypes and antimicrobial resistance patterns. METHODS: The minimal inhibitory concentrations (MIC) of seven antimicrobial agents and serotypes for 150 strains of GBS isolated from clinical specimens between 1990 and 1997 were investigated. RESULTS: The resistance rate of 150 clinical isolates of GBS were 20.0% to clindamycin, 16.0% to erythromycin, 4.0% to chloramphenicol, and 95.3% to tetracycline. None was resistant to penicillin, ceftriaxone, or vancomycin. Of the 24 isolates resistant to erythromycin, 20 (83.3%) were resistant to clindamycin. Resistance rates of erythromycin according to serotypes in decreasing order were 69.2% (V), 23.2% (III), and 3.5% (Ib). All serotypes Ia and II were susceptible to erythromycin and clindamycin. CONCLUSIONS: Striking emergence of resistant strains to erythromycin and clindamycin in our clinical isolates of GBS was mainly due to sudden increase of serotype V and III which shows multi-drug resistance phenotype.

Colonization Rate and Serotypes of Group B Streptococci in First Trimester of Pregnancy / 대한임상병리학회지

BACKGROUND: Group B streptococci (GBS) are the most common cause of sepsis and meningitis in newborns in the United States and Europe, and maternal colonization rate of GBS is the most important factor of group B streptococcal neonatal infections. But, in Korea, studies on the maternal colonization rate of GBS are rare due to low incidence of neonatal group B streptococcal infections, particularly, data on colonization rate of GBS during first trimester is nearly absent. The aim of this study was to establish the rates of maternal carriage of GBS and the distribution of GBS serotypes in first trimester of pregnancy. METHODS: During the period of June to December 1997, we studied women attending private clinic. A total of 309 women in first trimester were enrolled in the study. Cotton swab specimens from vagina and cervix were placed to new Granada tube medium. The new Granada tube medium with specimen swab was incubated in 5% CO2 atmosphere at 35degreesC. For the identification of GBS, the colonies showing orange color on new Granada tube medium were tested with Streptex group B Streptococcus reagent (Wellcome Diagnostics, UK). Serotyping was done by Hemolytic Streptococcus Group B Typing Sera (Denka Seiken, Japan). The typing sera used in this study were Ia, Ib, II, III, IV, and V. RESULTS: Of the pregnant women in first trimester, 2.3% (7/309) were colonized with GBS, and all seven women who colonized GBS were positive in vagina and cervix at the same time. Frequency of serotype III and Ib were 71.4% (5/7) and 29.6% (2/7), respectively. Serotypes Ia, II, VI, and V were absent. CONCLUSIONS: Maternal carriage rate of GBS in first trimester of pregnancy was 2.3%, and serotype III was the most common serotype. Serotypes Ia, II, VI, and V were absent.

Serotypes and Biochemical Reaction Patterns of Group B Streptococci / 대한임상병리학회지

BACKGROUND: This study is designed to provide data on the trend of serotypes of group B streptococci (GBS) isolated from clinical specimens during recent eight years and to elucidate the relationship between biochemical reactions and serotypes of GBS. METHODS: Serotyping, pigment production test, CAMP test, hippurate hydrolysis, and hemolysis test were performed for 150 GBS isolates from clinical specimens during March 1990 to February 1998. The typing sera used were Ia, Ib, II, III, IV, and V. Pigment production was detected by new Granada tube medium. The CAMP test and hippurate hydrolysis were performed by standard technique. Hemolytic patterns of GBS were determined on sheep blood agar and human blood agar plate. RESULTS: GBS were frequently isolated from cervix, urine, wound (pus), and blood. Striking increase of GBS isolates were notified from 1996 to 1997 period. Identification rates of GBS serotypes were Ib (38.0%), III (37.3%), Ia (9.3%), V (8.7%), nontypable strains (4.0%), and II (2.7%) in decreasing order. The proportion of serotype III increased markedly from 1996. Serotype V was not isolated until 1996, and ranked third in 1997. Seven (4.7%) isolates were nonhemolytic, and six of seven isolates revealed serotype III. Two (1.3%) isolates that were negative in both CAMP test and hippurate hydrolysis were serotype II. CONCLUSIONS: Clinical microbiology laboratories relying on beta hemolysis or pigment production for initial detection of GBS may underestimate the isolation rate of GBS and the proportion of serotype III which hardly makes hemolysis. It is therefore recommended that laboratories providing cultures for the GBS of genitalia specimens supplement other detection methods such as CAMP test or immunologic methods.