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J Med Microbiol. 2014 Oct;63(Pt 10):1395-9. doi: 10.1099/jmm.0.066738-0. Epub 2014 Jul 31.

Evaluation of chromogenic medium and direct latex agglutination test for detection of group B streptococcus in vaginal specimens from pregnant women in Lebanon and Kuwait.

Author information

1
Faculty of Health Science, University of Balamand, Lebanon Microbiology Unit, Department of Laboratories, Farwania Hospital, Kuwait.
2
Microbiology Unit, Department of Laboratories, Farwania Hospital, Kuwait Department of Microbiology, Faculty of Medicine, Kuwait alfouzan.w@hsc.edu.kw.
3
Department of Obstetrics and Gynecology, Saint George Hospital, Lebanon Department of Obstetrics and Gynecology, Faculty of Medicine, University of Balamand, Lebanon.
4
Depatrment of Microbiology, Makased Hospital, Lebanon.
5
Department of Obstetrics and Gynecology, Makassed Hospital, Lebanon.
6
Faculty of Health Science, University of Balamand, Lebanon.
7
Department of Obstetrics and Gynecology, Clemenceau Medical Center, Lebanon.
8
Department of Public Health, Faculty of Health Science, Lebanese International University, Lebanon.
9
Microbiology Unit, Department of Laboratories, Farwania Hospital, Kuwait.
10
Department of Internal Medicine, Faculty of Medicine, American University of Beirut, Lebanon.

Abstract

This study was undertaken to evaluate chromogenic medium and a direct latex agglutination test (DLA) for detection of Group B Streptococcus (GBS) in the vaginal specimens of pregnant women, and to ascertain the prevalence of GBS in this population in Kuwait and Lebanon. Vaginal swabs, collected from women at 35-37 weeks of gestation, were cultured on 5 % sheep blood agar (SBA), colistin nalidixic acid agar (CNA), Strept B Select chromogenic agar (SBS) as well as Lim enrichment broth in 168 cases in Lebanon while only SBA was used for 1391 samples in Kuwait. In addition, vaginal samples from 102 GBS-positive and 20 GBS-negative women near the time of delivery were collected in Kuwait for evaluation of the DLA test. During the study period, the prevalence of GBS colonization was determined to be 20.7 % (288/1391) in Kuwait while 18.4 % (31) of 168 pregnant women in Lebanon had vaginal cultures positive for GBS. By direct plating of vaginal swabs on the three media used, the isolation rates of GBS were 51.6, 64.5 and 77.4 % on SBA, CNA and SBS, respectively, which increased to 90.35, 93.1 and 96.8 %, respectively, following subculture in Lim broth after 18 h of incubation. The sensitivity of the DLA test was found to be dependent on the density of GBS colonization, resulting in 100 % sensitivity and 100 % specificity for heavy (>10(2) c.f.u. per swab) and moderately heavy (50-100 c.f.u. per swab) growth of GBS. However, for vaginal specimens yielding <50 c.f.u. per swab, the sensitivity, specificity, positive and negative predictive values of the DLA test were 100, 55.5, 63.6 and 100 %, respectively. In conclusion, a chromogenic agar, such as SBS, and a DLA test can be used for rapid detection of GBS in pregnant women. The DLA test, in particular, could prove to be a useful tool for immediate detection of GBS in women near delivery so that intrapartum antibiotic prophylaxis can be initiated.

PMID:
25082944
DOI:
10.1099/jmm.0.066738-0
[Indexed for MEDLINE]

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