A total of 283 pregnant mothers without signs and symptoms of UTI were included in this study. The prevalence of ASB among pregnant women in this study was 14.85% (n = 42/283). In this study, gram- negative bacteria (66.7%) were more prevalent than gram- positive bacteria (33.4%). (Fig. 1) which are consistent with other studies done in Adigrat Northern Ethiopia (64.1%) [14]. and studies done in Nairobi Kenya (78.8%) [15], central region of Iran (69.6%) [16] and Bengal India(62.3%) [17]. This might be due to the fact that most uropathogenic bacteria in pregnant women are gram negative that usually originate from the bowel and ascend to the upper urinary tract due to the close proximity of female urethra to the anal area. In addition, during pregnancy difficulties in cleaning genital area during defecation might result in contamination of female urinary tract with fecal bacteria (mostly gram-negative). However, our finding is in contrary to studies done in Dessie Northeast Ethiopia [18], Hawassa Southern Ethiopia [19], which reported the predominance of gram-positive bacteria over gram-negative bacteria among pregnant women with ASB. The possible explanation for this discrepancy might be due to differences in environmental conditions such as temperature and humidity between these different study areas and differences in the level of antimicrobial usage by patients among these different study sites, all of which could affect the distribution of bacteria in different countries and among different regions in the same country
. Regarding bacterial species, E. coli (50%) was the predominant bacterial isolates observed in this study followed by K. pneumonia (16.7%), S. aureus (14.3%), CoNS (11.9%) and GBS (7.1%). (Fig. 1). The predominance of E. coli in our study is consistent with studies done in Bahir Dar Northwest Ethiopia [21], Hawassa Southern Ethiopia [20] and studies done in Ghana [22], Egypt [23] and India [18].The acquired ability of E. coli to produce a number of virulence factors that facilitate colonization and invasion of the urinary epithelium might be one possible explanation for the predominance of E. coli in pregnant women with ASB [24]. Regarding the antimicrobial susceptibility pattern of bacterial uropathogens, the finding of our study showed that bacterial uropathogens isolated from pregnant women with asymptomatic UTI develop resistant to commonly used antimicrobial agents. In this study, Most of the Gram-negative bacterial isolates were sensitive to meropenem (96.4%), ceftazidm (85.7%), while were highly resistant for tetracycline (96.4%), ampicillin (92.9%), (Table 1). Our finding is in line with studies done in Dessie Northeast Ethiopia [24], Baghdad, Iraq [25], and Kanpur, India[26]. Which show that most of the Gram-negative isolates were sensitive to ceftazidm, ceftriaxone, cefotaxime, amikacin, tobramycin and ciprofloxacin and resistant to tetracycline and amoxicillin. However, our finding is in contrary to studies done in Kashmir [27], and Adigrat Northern Ethiopia [28]. Which show that most of the Gram-negative isolates were sensitive trimethoprim-sulfamethoxazole augmentin, nalidixic acid and gentamycin. The easy accessibility of the commonly prescribed antimicrobials over-the counter combined with the misuse of the antibiotics by both patients and clinicians due to lack of facilities and trained personnel for urine culture in most health facilities in Ethiopia and frequent use of common antimicrobial agents by peoples without prescription or medical supervision might be responsible for the observed high prevalence of antimicrobial resistance to commonly used antibiotics. Increased resistance of E. coli to β-lactamase inhibitors combined with the emergence of extended spectrum β-lactamase (ESBL) inhibitors (meropenem) resistant E. coli isolates (4%) in this study area is a worrying situation that needs continuous monitoring and surveillance of antimicrobial resistance of E. coli mainly in highly vulnerable groups such as pregnant women.
The finding of our study also showed that Gram-positive bacterial isolates were highly resistant for tetracycline (100%), trimethoprim-sulfamethoxazole (78.6%), penicillin (71.4%), augmentin (75%) and nalidixic acid (57.1%).(Table 2) Relatively similar resistance rates of Gram-positive isolates for these antibiotics are also reported from studies done in, Gondar Northwest Ethiopia [29], and India [18] which might be due to the indiscriminate and misuse of the antibiotics for empirical therapy. In this study, most of Gram-positive bacteria isolates were sensitive for ceftazidime (100%), vancomycin (92.9%,), clindamycin (92.9%), tobramycin(85.7%),chloramphenicol (78.6%), norfloxacillin (70.4%), ciprofloxacin(64.3%) and erythromycin (64.3%). Relatively similar susceptibility rate of Gram-positive isolate to most of these antimicrobial agents are reported from studies done in Adama Central Ethiopia [15].which might be due to the relative inaccessibility of these antibiotics over the counter.
In this study, multi drug resistance (MDR = resistance in ≥ 3 drugs) was seen in 76.2% of the isolated bacterial uropathogens. Our finding is higher than studies done in Dessie Northeast Ethiopia (72.4%) [19], Tikur Anbessa Specialized Hospital Addis Ababa (74%) [30]. The high prevalence of MDR reported in this study might be due to the unrestricted availability and high rate of use of prescribed drugs. It could also be related to the rapid spread of resistant bacteria and high misuse of antimicrobial drugs such as self-medication, unnecessary use, failure to adhere to standard treatment guideline, lack of appropriate infection prevention strategies and inadequate or absence of antimicrobial drug resistance surveillance program.
Table 1
Antimicrobial susceptibility pattern of gram-negative bacteria isolated from the urine of pregnant women
Bacterial isolates (no.) | | Antimicrobial agents tested |
| | TER | NA | CIP | SMT | GEN | AMK | TOB | AMP | AMX-C | CEF | CTX | CAZ | MER |
E. coli (n = 21) | S | 1 4.8 | 9 42.9 | 14 66.6 | 5 23.8 | 10 47.6 | 18 85.7 | 21 100 | 2 9.5 | 5 23.8 | 15 71.4 | 16 76.2 | 17 81 | 20 95.2 |
| R | 20 95.2 | 12 57.1 | 7 33.4 | 16 76.2 | 11 52.4 | 3 14.3 | 0 0 | 19 90.5 | 16 76.2 | 6 28.6 | 5 23.8 | 4 19 | 1 4.8 |
K. pneumonia(7) | S | 0 0 | 2 28.6 | 2 28.6 | 0 0 | 2 28.6 | 3 42.9 | 3 42.9 | 0 0 | 2 28.6 | 3 42.9 | 2 28.6 | 7 100 | 7 100 |
| R | 7 100 | 5 71.4 | 5 71.4 | 7 100 | 5 71.4 | 4 57.1 | 4 57.1 | 7 100 | 5 71.4 | 4 57.1 | 5 71.4 | 0 0 | 0 0 |
Total (n = 28) | S | 1 3.6 | 11 39.3 | 16 57.1 | 5 17.9 | 12 42.9 | 21 75 | 24 85.7 | 2 7.1 | 7 25 | 18 64.3 | 18 64.3 | 24 85.7 | 27 96.4 |
| R | 27 96.4 | 17 60.7 | 12 42.9 | 23 82.1 | 16 57.1 | 7 25 | 4 14.3 | 26 92.9 | 21 75 | 10 35.7 | 10 35.7 | 4 14.3 | 1 3.6 |
S: susceptible; R: resistant; CPR: ciprofloxacin; TER: tetracycline; STX: trimethoprim-sulfamethoxazole; CEF: ceftriaxone; AMP: aampicillin; Amox-clav: amoxicillin-clavulanic acid; CAZ: ceftazidime; GEN: gentamycin; AMK: amikacin; MER: meropenem;NA: nalidixicacid;COF: cefotaxime |
Table 2. Antimicrobial susceptibility pattern of gram-positive bacteria isolated from the urine of pregnant women
Bacterial isolates (no.) | Antimicrobial agents tested |
| | CLI | ERY | CAF | PE | CAZ | NA | TOB | CIP | STX | NOR | VAN | TET |
S. aureus(6) | S | 6 (100) | 4 (66.7) | 5 (83.3) | 1 (16.7) | 6 (100) | 3 (50) | 6 (100) | 4 (66.7) | 1 (16.7) | 5 (83.3) | 5 (83.3) | 0 (0) |
| R | 0 (0) | 2 (33.3) | 1 (16.7) | 5 (83.3) | 0 (0) | 3 (50) | 0 (0) | 2 (33.3) | 5 (83.3) | 1 (16.7) | 1 (16.7) | 6 (100) |
CoNS (5) | S | 4 (80) | 3 (60) | 4 (80) | 2 (40) | 5 (100) | 2 (40) | 4 (80) | 3 (60) | 1 (20) | 3 (60) | 5 (100) | 0 (0) |
| R | 1 (20) | 2 (40) | 1 (20) | 3 (60) | 0 (0) | 3 (60) | 1 (20) | 2 (40) | 4 (80) | 2 (40) | 0 (0) | 5 (100) |
GBS(3) | S | 3 (100) | 2 (66.7) | 2 (66.7) | 1 (33.3) | 3 (100) | 1 (33.3) | 2 (66.7) | 2 (66.7) | 1 (33.3) | 2 (66.7) | 3 (100) | 0 (0) |
| R | 0 (0) | 1 (33.3) | 1 (33.3) | 2 (66.7) | 0 (0) | 2 (66.7) | 1 (33.3) | 1 (33.3) | 2 (66.7) | 1 (33.3) | 0 (0) | 3 (100) |
TOTAL(14) | S | 13 (92.9) | 9 (64.3) | 11 (78.6) | 4 (28.6) | 14 (100) | 6 (42.9) | 12 (85.7) | 9 (64.3) | 3 (21.4) | 10 (71.4) | 13 (92.9) | 0 (0) |
| R | 1 (7.1) | 5 (35.7) | 3 (21.4) | 10 (71.4) | 0 (0) | 8 (57.1) | 2 (14.3) | 5 (35.7) | 11 (78.6) | 4 (29.6) | 1 (7.1) | 14 (100) |
CLN: clindamycin; ERY: erythromycin; CAF: Chloramphenicol; Pen: penicillin; CAZ: ceftazidime; CPR: ciprofloxacin; TET: tetracycline; STX: trimethoprim-sulfamethoxazole; NOR: norfloxaci; VAN: vancomycin; |