Prevalence of aerobically growing opportunistic bacteria in the nasopharyngeal microbiota of pregnant women living in rural and urban areas

The upper respiratory tract, including the nasopharynx, is inhabited by many microbial species. Still, the nasopharyngeal microbiota (or microbiome) of pregnant women is not well understood and may be influenced by a number of factors, including place of residence. Many changes occur during pregnancy, and their association with the respiratory microbiota is important for the health of the mother and for the developing fetus. The aim of this study was to compare the colonisation of the nasopharyngeal cavity by culturable aerobic bacteria in the microbiota of women with a physiological pregnancy course according to rural or urban place of residence. Nasopharyngeal swabs were collected from 37 pregnant women (17 from rural and 20 from urban areas) to detect the colonisation of aerobically growing culturable bacteria. Isolates were identified using microbiological culture methods and the MALDI-TOF MS technique. Bacteria were colonisers of the nasopharynx cavity in all cases tested. Accordingly, 97.3% (36/37) of the pregnant women were colonised by Gram-positive bacteria, mainly coagulase-negative (CoNS) and -positive (CoPS) Staphylococcus spp. and Corynebacterium spp. in both the rural and urban groups. Gram-negative Klebsiella variicola, Proteus mirabilis and Pseudomonas congelans colonised only 17.6% (3/17) of rural women and Stenotrophomonas maltophilia only 5.0% (1/20) of the urban women. To summarise, all pregnant women were colonised with bacteria in the nasopharyngeal cavity. The majority from both rural and urban residences were colonised with Gram-positive bacteria only. Gram-negative bacteria were isolated mainly from samples in the rural group.