In the present study, a comprehensive molecular characterization of six bacterial isolates was carried out. We observed that the sequence in sample 1 was 100% identical to the partial gene sequence of 16S rRNA of
E. coli strain
U5/41. Phylogenetically strains included
U5/41, E. fergusonii strain
ATCC35469, E. fergusonii strain
NBRC102419, E. coli strain
JCM1649, E. fergusonii strain
ATCC35469, Shigella flexneri strain
ATCC29903, E. coli strain
NBRC102203, Shigella boydii strain
P288, Shigella sonnei strain
CECT4887, and
Brenneriaalni strain pvfi20. Campos et al. also conducted a study in Brazil, of
E. coli isolated from urine samples of hospitalized patients and identified strains 131 and 69 as the most frequently found
E. coli strains (
6). Strain 69 was found to be associated with both community-acquired and healthcare-associated UTIs (
7). The MDR manner of these strains was attributed due to the dfrA17-aadA5 gene, which makes these strains resistant to Trimethoprim, aminoglycosides. The other ST groups identified by Campos et al. included
ST648, ST405, ST73, and
ST10.
The sequence of sample 2 was 100% identical to that of the partial gene sequence of 16S rRNA of Klebsiella aerogenes strain F26. The phylogenetically identified strains were F26, K. aerogenes strain NCTC10006, K. aerogenes strain NCTC10006, K. aerogenes strain FDAARGOS_513 chromosome, K. aerogenes strain CB46l, K. aerogenes strain FDAARGOS_327 chromosome, K. aerogenes strain DAS43, K. aerogenes strain gol2, K. aerogenes strain NCTC9735, and K. aerogenes strain CX-122.
In sample 3, the sequence was 100% identical to that of Pseudomonas entomophila strain 2014. The phylogenetically identified strains were P. entomophila strain 2014, P. entomophila strain 1257 chromosome, Bacterium strain E70 16S ribosomal RNA gene, P. putida strain CK223, P. spp strain AZ5, P. guariconensis strain njensis, P. spp strain BYT-1, P. spp WCHPs060039, P. guariconensis strain MR149, and P. guariconensis strain MR144.
In sample 4, the sequence was 100% identical to that of Staphylococcus aureus strain NCTC13616. Phylogenetically identified strains included S. aureus strain NCTC13616, S. aureus strain NCTC4163, S. aureus strain NCTC11965, S. aureus strain NCTC4137, S. aureus strain NCTC9555, S. aureus strain NCTC5660, S. aureus strain NCTC7121, S. aureus strain NCTC13142, S. aureus strain NCTC12233, S. aureus strain NCTC13552.
In sample 5, the strain identified was Staphylococcus saprophyticus strain FDAARGOS_355. The other phylogenetically identified strains were S. saprophyticus strain FDAARGOS_355, S. saprophyticus strain FDAARGOS_137, S. saprophyticus sub spp. saprophyticus ATCC 15305, S. saprophyticus strain RJ17, S. saprophyticus sub spp. saprophyticus ATCC 15305, Staphylococcus spp. S04009, S. saprophyticus sub spp. saprophyticus strain NCTC7666, S. saprophyticus strain FDAARGOS_336, S. spp 82B, S. saprophyticus strain BVC51.
The sequence of the sample was 100% identical to that of the partial gene sequence of 16S rRNA of Proteus mirabilis strain NCTC 11938. The phylogenetically identified strains were P. mirabilis strain NCTC 11938, P. mirabilis strain PmSC1111, P. mirabilis strain NCTC4199, P. mirabilis strain AR_0029, P. mirabilis strain AR379, P. mirabilis isolate GN2, P. mirabilis strain AR_0156, P. mirabilis strain AR_0159, P. mirabilis strain AR_0059, and P. mirabilis strain AOUC-001.
Jenkins et al. obtained pus samples and joint fluids from 23 patients using 1,343 bp PCR. Of 38 samples using 762/598 bp PCR, 33 samples were negative by both culture and PCR. Moreover, 16S rDNA was identified in 8/17 culture-positive samples (
8). The bacteria identified were
S. aureus, Streptococcus pneumoniae, Streptococcus viridians, Prevotella pleuritidis, and
Prevotella oulorum. Gene sequencing helped in identifying anaerobes in samples positive on culture. As the Gram-positive cell wall is disrupted readily during the extraction process, it is not identified as easily as Gram-negative bacteria (
9-
12). However, Jenkins et al. found that for both Gram-negative and -positive bacteria, there was no bias as they could not be identified by PCR (
8).
Van der Zee et al. demonstrated that PCR-based detection can replace the culture-based diagnosis except in the case of antibiotic sensitivity testing that might be essential for the adequate treatment of patients. These results were confirmed by 16S PCR. However, the limitation of this study was that only a few strains were tested, and hence, the presence and homology of target genes need further substantiation (
13).
Tajbakhsh et al. isolated and detected Gram-negative bacteria, causing UTI in patients from Shahrekord Hospitals, Iran. The study used PCR, which was found to be an effective method for diagnosis of bacteria causing UTI, especially Gram-negative ones and also other infections (
14).
Abulmeshah carried out a study to identify organisms causing UTI by doing 16S rRNA gene sequencing and BLAST analysis and found that
E. coli, K. pneumoniae, S. aureus, P. mirabilis and
P. aeruginosa were the most prevalent organisms (
15).
5.1. Conclusions
Six bacterial isolates were analyzed by 16S rRNA gene sequencing, followed by the construction of a phylogenetic tree formation up to the species level. This method was a valuable tool for a cost-effective and accurate diagnosis of an array of uropathogens in both asymptomatic and symptomatic pregnant women. If the samples presented MDR on sensitivity testing, the specific strain isolated by PCR would provide guidelines for the management of UTI in pregnant women in the future.