A Clinico-microbiological Study of Urinary Tract Infections in Pregnant Women attending Antenatal Clinic of a Tertiary-level Hospital with Special Reference to Antimicrobial Sensitivity Pattern

• The high prevalence of UTI in general and asymptomatic bacteriuria in particular in pregnant population as observed in our study lead us to suggest that compulsory screening for UTI in pregnancy be continued in the current study setting and be started in other health centers across the developing World and which when diagnosed early can eventually reduce fetal and maternal morbidity and mortality.
• Multidisciplinary awareness and inter-disciplinary communication regarding the uropathogens and antimicrobial susceptibility pattern are necessary in successful treatment and controlling the rising trends of antimicrobial resistance (AMR) more so in vulnerable population like pregnant mothers.
• The rising trends of drug resistance in uropathogens against commonly prescribed antimicrobials like Penicillin, co-trimoxazole etc. raises conflicting and ambiguous scenario in the choice of antimicrobial therapy. An antibiotic policy based on local data and involving all sections of the population is the only answer to this ‘global headache’ of drug resistance.

Table 2: Prevalence of UTI among pregnant women.

Table 3: Association between socio-demographic and obstetric variables of pregnant women and prevalence of UTI

We observed a prevalence of UTI in pregnant women of 30.35% (Table 2),which was comparable with the prevalence rates reported in studies in Bangladesh (30%) and Egypt (31.3%)[17, 18] and higher compared to the findings of Gour et al. (20.27%) and Kant et al. (3.3%) in North India, and Thomas et al. (25%) in South India, respectively [2, 3, 13].However, Sibi G et al. (46.6%) in South India and Rizvi et al. (51.2%) in North India reported a higher prevalence of UTI [10, 14].

The prevalence of asymptomatic UTI (21.39%) among pregnant women was found to be higher than the prevalence of symptomatic UTI (8.96%) in pregnant women in our study (Figure 2) like Thomas et al. and Rizvi et al. [13, 14] However, Kant et al. and Vaijanathrao et al. found a higher prevalence of symptomatic UTI compared to asymptomatic UTI, which was opposing our study findings [3, 19] .The higher prevalence of asymptomatic bacteriuria in our study was alarming since asymptomatic bacteriuria might not be detected early due to lack of symptoms and may rapidly progress to acute pyelonephritis causing significant morbidity for mother and fetus [9].The high prevalence of UTI in general and asymptomatic bacteriuria in particular in pregnant population as observed in our study lead us to suggest that compulsory screening for UTI in pregnancy be continued in the current study setting and be started in other health centers in India and across the developing World.

In our study, 42.62% of pregnant women diagnosed with UTI belonged to the age-group of 20 - 25 years followed by 26.23% who were of the age group of 26 - 30 years, which together amounted to 68.85% of total cases of UTI (Table 4). Similar patterns were also reported by Thomas et al., Ahmed et al. and Elazayat et al. [13, 15, 20].This led us to conclude that pregnant women in the age range of 20 - 30 years constitute a high-risk group for UTI [13, 15].The reasons for high prevalence of UTI in young age group can be attributed to early sexual activity, early child bearing and early marriage [9] as concluded by Jalali et al. in their study on more vulnerable pregnant population [21]. Our study found the association between maternal age and prevalence of UTI to be statistically significant (p value < 0.00001) (Table 4), like studies by Laari et al. and Al Kashif et al. [19, 22] However, some other studies did not find significant association between maternal age and risk of UTI [18, 28].

In our study, 55.74% of pregnant women suffering from UTI were homemakers (Table 3). This finding is contradictory to the findings of Al-Kashif et al. who found pregnant females with UTI employed in work (57.4%) were more than homemakers [22]. The study findings by Multani et al. in North India were also in disagreement with our results [23]. In our study, it was observed that working women could possibly  might not be able to attend the antenatal clinic regularly due to work constraints resulting in lower numbers being reported [24].With regard to literacy, the prevalence of UTI was found to be higher in illiterate females (69.67%) than among literate females (30.33%) (Table 3) with a p value < 0.00001which was similar to most other studies [18, 25, 26]; This could probably be attributed to lack of awareness and knowledge among illiterate pregnant women on hygienic practices related to urination.

Our investigations revealed that UTI cases in rural population significantly surpassed urban population, with a p value = 0.000713(Table 3). This was in concordance with the study by Multani et al. in Haryana, India [23].The reason for higher prevalence of UTI in rural population might have been due to non-compliance to hygienic sanitary conditions in villages, lack of awareness and lower concern for personal and environmental hygiene in rural population which increased the risk for UTI [21].This necessitates need for better outreach programs on hygiene and increasing accessibility of antenatal services in rural areas of all developing nations.

The maximum number of cases of UTI were found in the 3^rd trimester of pregnancy (47.54%) followed by 2^nd trimester (31.97%) and 1^st trimester (20.49%) respectively with a p value = 0.002721 (Table 3). The observed trend in our study thus shows that prevalence of UTI increases with increase in gestational age like Kant et al. and Sibi G et al. in their studies in North India and South India respectively [3, 10].Gour et al. and Johnson et al. also reported highest proportion of females with UTI in the 3^rd trimester of pregnancy [7, 27]. The enlarging uterus in later trimesters exerts more pressure on the urinary bladder causing increase in the intra-vesicular pressure and consequent vesico-ureteric reflux culminating in retention of urine which acts as a suitable environment for bacterial growth [9]. We suggest that screening for bacteriuria be done in the first antenatal visit, regardless of gestational age.

Our study reported a high proportion of pregnant women with UTI were multiparous with a p value =0.001201 (Table 3) similar to findings of Haider et al. [25] Multiparity is a known risk factor for UTI in pregnancy as it causes widening of orifice of urethra and descent of organs of pelvic cavity which aids in ascent and colonization of urinary tract by microbial pathogens[20].Likewise, the prevalence of UTI was higher in multigravida accounting for 72.31% of total cases of UTI with a p value = 0.001254 (Table 3) which was in agreement of findings in studies by Al-Kashif  and Mohamed et al.[22, 28].

Escherichia coli was the most common causative microorganism responsible for UTI in our study with a prevalence rate of 68.03% (Figure 3)which was similar to majority study findings in India and abroad [2, 5, 7, 10] .Urinary stasis in pregnancy is regarded as the most crucial factor predisposing to colonization of the urinary tract by Escherichia coli [29].The proportion of cases of UTI caused by Escherichia coli as reported in our study was found to be close to the findings  by Sabharwal(63.3%)[5] whereas Jyoti Jojan et al. reported Staphylococcus aureus (82.6%) to be the most predominant uropathogen  [30], which was not in agreement with our findings. Ansari et al. reported that Klebsiella pneumoniae (28.57%) and Staphylococcus aureus (28.57%) were responsible for maximum number of cases of UTI in pregnancy [31] whereas our study reported Klebsiella pneumoniae as the second most common uropathogen (18.85%) followed by Pseudomonas aeruginosa (4.1%) and Proteus vulgaris (3.28%) respectively (Figure 2). Gour et al. also reported Klebsiella pneumoniae to be the second most predominant (13.33%) in concordance with our study [7]. Sibi G et al. found a different species of Klebsiella namely Klebsiella oxytoca to be the second most common followed by Klebsiella pneumoniae in their study [10]. The study by Shailja et al. and Thomas et al. however found Coagulase negative Staphylococcus (17.1%) and Pseudomonas aeruginosa (25%) to be the second most common uropathogens respectively [2, 13].

Among the Penicillin group of β lactam antibiotics, a high overall resistance to amoxicillin-clavulanic acid (88.52%) and ampicillin (86.88%) was shown by uropathogens (Figure 4) like most other studies [5, 15]. The high resistance to these drugs can be attributed to rampant spread of beta-lactamase producing strains of bacteria [10] Most Gram-positive bacteria were highly resistant to both drugs in our study with the sole exception of Enterococcus faecalis which was fully sensitive to both the antibiotics. The high resistance of Staphylococcus species to ampicillin and amoxicillin-clavulanic acid in our study agreed with many other studies [7, 15, 32, 33]. However, both Samaga and Sadhvi et al. reported Enterococcus isolates to be 100% resistant Amoxycillin-Clavulanic acid and Ampicillin [32, 33]. Among Gram-negative bacteria, Escherichia coli isolates showed an alarmingly high resistance to amoxicillin- clavulanic acid (91.57%) and ampicillin (86.75%) respectively like several other studies. [7, 15, 32, 33] Klebsiella pneumoniae also showed high resistance to ampicillin and amoxicillin-clavulanic acid in our study comparable to findings of Ahmed et al. and Samaga et al. [15, 32]. Indiscriminate use of these antibiotics resulting in alarming drug resistance has made these unsuitable to be included in empirical treatment despite being traditionally safe drugs in pregnancy. The only effective drug from this group is piperacillin-tazobactam which showed an overall high sensitivity of 60.65% in our study. Staphylococcus aureus and Coagulase negative Staphylococcus had 100% sensitivity to piperacillin-tazobactam which contradicted study findings of Sadhvi et al[33]. The sensitivity rates of Escherichia coli (57.83%) and Klebsiella pneumoniae (47.83%) in our study were however lower than that reported by Kaushal et al. [4]

Apart from cefepime, bacterial uropathies were found to be moderately resistant to all other cephalosporins with resistance rates ranging between 50% and 65% (Figure 4). This might be due to extended spectrum beta lactamase (ESBL) producing organisms. Cefuroxime had an overall sensitivity of 23.77% in our study which was lower than that reported by Shamim et al. [34]. The overall sensitivity of ceftriaxone in our study is 31.97% which was comparable to the findings of Sabharwal et al. but lower than that found by Sibi G et al. [5, 10] Cefoperazone-sulbactam showed an overall sensitivity of 38.52% which was similar to study findings of Sabharwal et al. [5]

Klebsiella pneumoniae reported a sensitivity of 21.74% to cefuroxime which was similar to the finding of Sadhvi et al. [33]. The percentage sensitivity of uropathogens against Ceftriaxone was as following: Escherichia coli (32.53%), Klebsiella pneumoniae (26.09%), Pseudomonas aeruginosa (40%), Staphylococcus aureus (50%) and Staphylococcus saprophyticus (33.33%) which was lower than that noted by Ali et al. [35]

In our study, the bacterial uropathogens demonstrated a very high sensitivity to Carbapenems: imipenem and meropenem with a total sensitivity rate of 90.98% and 81.96% respectively (Figure 4) similar to findings of Sabharwal et al [5]. High sensitivity towards imipenem was observed among Escherichia coli (92.77%) in our study, similar to several other observers [7, 14, 32.  Klebsiella pneumoniae also showed high sensitivity to imipenem in our study (82.61%) comparable to other studies. [7, 27,36] The sensitivity rates of meropenem to Escherichia coli (80.72%) and Klebsiella pneumoniae (82.61%) in our study which was lower than that reported by Kaushal et al. [4] Imipenem was 100% sensitive to all Gram-positive isolates in our study (Table 5). Sadhvi et al. reported 100% sensitivity of Enterococcus spp. to imipenem which was in agreement with our findings [33].

Our study reported an overall high resistance of 68.03% to co-trimoxazole (Figure 4) like Sabharwal and Sibi G et al. [5, 10]. Escherichia coli demonstrated high resistance to co-trimoxazole of 66.27% (Table 4), which was in disagreement with a study by Patnaik et al. who reported 100% sensitivity of Escherichia coli to cotrimoxazole [37]. Pseudomonas aeruginosa showed very high resistance to cotrimoxazole in our study (Table 4), this finding was similar to observations of Derese et al. in Ethiopia [40]. Unlike most Gram-positive bacterial isolates in our studies, Coagulase negative Staphylococcus showed high sensitivity (66.67%) to co-trimoxazole (Table 8) similar to study findings by Rohini et al. [36]. The results of our study together suggest that co-trimoxazole is less effective in treating UTI in pregnancy, a view corroborated by Sibi G et al [10].

Our study found out that the uropathogens demonstrated an overall sensitivity rate of 54.10% to nitrofurantoin (Figure 4), which was lower than that reported in rest of India and Uganda. [5, 27]. Staphylococcus aureus showed high sensitivity to nitrofurantoin (Table 5), like some studies in India and abroad [2, 27]. Although Shailja et al. and Thomas et al. reported 33.3% and 25% resistance to nitrofurantoin for Enterococcus faecalis respectively, while our study reported no resistance (Table 5). Sensitivity rates showed that nitrofurantoin was effective against Escherichia coli (60.24%) and Proteus vulgaris (75%) in agreement with Johnson et al. [27] However, Klebsiella pneumoniae differed from other Gram- negative isolates in our study since it showed resistance of 82.61% to nitrofurantoin. High resistance of Klebsiella pneumoniae to nitrofurantoin had also been reported in a study in Ethiopia [38].

Fosfomycin was found to have an overall sensitivity of 81.97% (Figure 4) in our study which was comparable to the study by Souza et al. in Brazil [39]. Fosfomycin was found to be highly effective against most Gram-negative and Gram-positive uropathogens in our study except for Pseudomonas aeruginosa which was reported to have only 20% sensitivity. High sensitivity of Fosfomycin to both Gram-positive and Gram-negative pathogens was also reported by Rosana et al. [40] Among the Gram-negative uropathogens, Escherichia coli and Proteus vulgaris were most sensitive with sensitivity rates of 93.98% and 75% respectively (Table 4). Half of the isolates of Staphylococcus aureus and Enterococcus faecalis were sensitive while 66.67% of the isolates of Staphylococcus saprophyticus were sensitive (Table 5). Our findings on sensitivity of Enterococcus fecalis against Fosfomycin were in disagreement with that of Rohini et al. which reported 100% sensitivity [36]. The overall high sensitivity and wide spectrum of action of Fosfomycin leads us to suggest its use in empirical treatment. Similar to us, Souza et al. and Rosana et al. have also recommended use of Fosfomycin in empirical treatment of UTI in pregnancy [39, 40]. This is also in accordance with the recommendations of the Indian Council of Medical Research [11].

CONCLUSION

The high prevalence of UTI in our study leads us to conclude that regular screening of UTI in pregnancy is essential to avert maternal and foetal complications. The sensitivity patterns of bacterial uropathogens to different antimicrobials in our study lead us to suggest use of carbapenems and Fosfomycin in empirical treatment of UTIs in pregnancy.

Funding: This was a self-funded project. The first author was awarded a onetime stipend of INR 50,000/-as part of ICMR-STS. The study was conducted using existing institutional infrastructure.

Conflict of Interest: None.

Ethical approval: The study was conducted after it was ethically reviewed and approved by the Institutional Ethics Committee (IEC) of our apex teaching hospital.

Availability of data and materials:

Author contribution: We declare that all listed authors have made substantial contributions to all of the following three parts of the manuscript:

- Research design, or acquisition, analysis or interpretation of data;

- Drafting the paper or revising it critically;

- Approving the submitted version.

We also declare that no-one who qualifies for authorship has been excluded from the list of authors.

ACKNOWLEDGMENT

This study by Mr. Soham Basu (Final year student of MBBS, IPGME&R and SSKM Hospital, Kolkata, India) under the guidance of Prof. Dr. Kumkum Bhattacharyya (Professor of Microbiology, IPGME&R and SSKM Hospital, Kolkata, India) and Dr. Abirlal Sanyal (Demonstrator, IPGME&R and SSKM Hospital, Kolkata, India) was selected by Indian Council of Medical Research (ICMR) for Short Term Studentship (STS) in the year 2022 (Reference ID: 2022-04795).