Genital Group B Streptococcus carriage in the antenatal period: its role in prom and preterm labour

Of 326 high vaginal swabs taken during the antenatal period, Group B Streptococcus (GBS) was isolated from the birth canal in 46 women, giving a carrier rate of 14.1%, which is within the often quoted range of between 5% - 25% in different parts of the world. Carriage rates were similar at different gestations. In a subgroup of 34 women, 2 swabs taken at least 5 weeks apart yielded results which were discordant in over one fifth of the time. This knowledge of the natural history of GBS carriage questions the practice of treating asymptomatic carriers of GBS in the antenatal period to prevent transmission of GBS to the neonate. The group of women with positive swabs in the antenatal period did not have a significantly higher incidence of preterm labour and/or prelabour rupture of membranes (PROM) compared with the group of women with negative swabs. Routine screening of the antenatal population for GBS carrier status prior to 32 weeks gestation may not identify women at high risk of PROM or preterm labour.

Comparison of multiplex PCR and culture for detection of Legionellae in cooling tower water samples

We compared multiplex polymerase chain reaction (PCR) and culture for detecting the presence of Legionella pneumophila and Legionella spp in cooling tower water samples. Multiplex PCR was performed after phenol extraction of DNA from the samples. The set of primers for the PCR assay involved the 5S rRNA (Legionella spp) and the mip (macrophage infectivity potentiator gene, specific for L. pneumophila) genes as target sequences for amplification. Both the sensitivity and the specificity of the PCR assay were 100% when the 5S rRNA gene was used as target sequence. Isolation of Legionellae from the samples was observed only with the PCR-positive samples. We propose that PCR be used as a screening test before attempting to culture Legionellae from cooling tower water samples.

Antimicrobial susceptibilities of clinical isolates of Acinetobacter baumannii from Singapore

The in vitro activities of 17 antimicrobial agents alone or in combination against 70 clinical isolates of Acinetobacter baumannii from Singapore were determined by broth microdilution. The MICs of amoxicillin, ampicillin, ceftazidime, ceftriaxone, gentamicin, and piperacillin for 90% of the strains were > or = 128 micrograms/ml. Addition of sulbactam to ampicillin produced improved activity, whereas adding tazobactam to piperacillin did not. The MICs of amikacin, ciprofloxacin, and imipenem for 90% of the strains were 32, 32, and 16 micrograms/ml, respectively.

Prevalence in Singapore of enterococci with high-level resistance to aminoglycosides and comparison of three methods for their detection

The first study of the prevalence in Singapore of enterococci with high-level resistance to aminoglycosides has been made in the National University Hospital. From March to June 1992, 225 isolates were studied by means of three methods: (1) use of brain-heart infusion (BHI) agar incorporating the antibiotic; (2) microdilution of the antibiotic in broth; and (3) use of high content antibiotic discs. The BHI agar was the reference method. Of the total, 49 (22%) isolates were resistant to gentamicin, 86 (38%) to streptomycin, 82 (36%) to kanamycin and 93 (41%) to one or more of the agents. Results of the disc diffusion method correlated completely with the BHI agar method. The broth microdilution method showed a 100, 90 and 96% sensitivity in relation to gentamicin, streptomycin and kanamycin, respectively, and a specificity of 100% for all three aminoglycosides. Statistical significance (P < 0.01 to P < 0.001) was demonstrated in (1) a greater incidence of enterococci with high-level resistance to aminoglycosides among blood isolates; (2) gentamicin resistance predicting kanamycin high-level resistance; and (3) more resistance to gentamicin, streptomycin and kanamycin among Enterococcus faecium isolates compared to those of Enterococcus faecalis. Beta-lactamase activity was not detected.