The study comprised 420 participants. Of these, a significant proportion (32.85) of specimens were obtained from patients aged between 41 and 50 years; 54.29% of them were female; 56.33% of them were from urban regions; 30.48% had a secondary school certificate; and 30% of the specimens originated from urine. This is similar to the results of a recent investigation [20, 21].
In this study, the overall rate of gram-negative bacteria was 49.76%. This finding is lower than reports at 77.1% in Ecuador [22] and 79.4%. In addition, these data are higher than those reported in Ethiopia (16.9%) [20], Mexico (19.1%) [23], and Nepal (17%) [24].
The high rate of GNB prevalence in our study may be due to several reasons, including misuse and overuse of antimicrobials, lack of access to clean water, poor practical hygiene, poor infection and disease prevention and control, poor access to quality, affordable medicines, and lack of awareness and knowledge.
Regarding age, a high rate of GNB was 57.97% observed in the current study among the age group of 41–50 years. This study is supported by earlier studies that documented that patients over 45 years of age had a high rate of microbial infections [24; 26]. Older people may get sick more often because their bodies do not work well enough, and their immune systems become weaker [27].
The present data showed that GNB were more significant among female patients than among male patients. However, as this study found, most studies indicated that UTIs in women predominate over UTIs in men, with UTIs being identified as diseases in women [25]. Poor personal cleanliness and anatomical predispositions that allow bacteria to enter the bladder may be the main causes, compared to men. In different reports, gram-negative infections were more frequently observed in males [27, 28].
In the current study, uneducated patients were more exposed to GNB infection than others. Several studies have been conducted in different Yemeni regions that support this finding [29–30]. Education enhances the likelihood of a long and healthy life and has the potential to reduce health disparities [31].
According to specimen type, the frequency of GNB was recorded in 51.28% of urine specimens. A comparable study by Helmy et al. [25] in Cairo, Egypt found that the most common source of microbial illnesses was urine specimens. In addition, several studies conducted in Yemen supported this data [32–33]. Previous studies have indicated that gram-negative bacteria are responsible for approximately 90% of UTI cases, whereas gram-positive bacteria account for only 10% of cases [34]. Approximately 150 million people worldwide are afflicted with urinary tract infections (UTIs), which are among the most widespread microbiological illnesses associated with hospitals and communities [35].
The prevalence of GNB in the vaginal specimens was 60.42%. This finding is higher than the prevalence of GNB reported in a similar study [36]. Variations in the prevalence rates of bacterial vaginosis have been linked to sociodemographic characteristics, sexual behavior, reproductive health information, and behavioral and genital hygiene. Additionally, an increase in the rate of vaginal infections has been reported in Yemen [37–39].
Most bacteria recovered from the patients in this study were E. coli (36.62%), followed by K. pneumoniae (18.66%), Enterobacter sp. (12.32%), and Acinetobacter spp. (10.92%), P. aeruginosa (9.15%), Citrobacter sp. (6.34%), and P. mirabilis (5.99%), respectively. This is in agreement with previous results obtained from different countries [20; 26, 40] which found that E. coli, K. pneumoniae, and Proteus sp. were the most frequently isolated gram-negative bacteria. Another study revealed that K. pneumoniae and P. aeruginosa are the most frequently isolated GNB infections [28].
The observable variations in the overall prevalence and occurrence of gram-negative bacteria may be attributed to the sources and numbers of clinical samples collected, the nature of infections, patient types or wards where the samples were obtained, and geographical disparities employed in each study.
E. coli showed greater resistance to imipenem (97.22%), tetracycline (84.62%), and enrofloxacin (78.85%). Moreover, resistance to meropenem and chloramphenicol was only moderate at 55.77% for each drug. These results are consistent with those of earlier studies that reported resistance rates to these antibiotics ranging from 70–90%. Almutawif et al. [34] found that over 50% of isolated E. coli strains were resistant to 10 of the 18 tested antibiotics. In contrast, at rates of 92.3% and 89.4%, E. coli was extremely susceptible to imipenem and meropenem, respectively. Additionally, E. coli showed different levels of resistance to cefuroxime (87.95%) [23], tetracycline (76.7%) [36], and chloramphenicol (46%) [24].
In this study, resistance of K. pneumoniae isolates to imipenem (100%) and norfloxacin (92.46%) was observed. A similar study by Almutawif et al. [34] reported that 59.7% and 44.7% of Klebsiella spp. isolates were resistant to meropenem and imipenem, respectively. In addition, resistance rates of over 65% of K. pneumoniae isolates have been reported for cefoperazone, ceftriaxone, cefotaxime, ciprofloxacin, norfloxacin, and ofloxacin [24]. Additionally, it was observed that between 64.3% and 81.55% of isolated K. pneumoniae were resistant to the cefuroxime antibiotic [23, 41]. Moreover, K. pneumoniae has been found to be highly resistant to tetracycline [42].
These data demonstrated that the highest resistance rate of P. aeruginosa isolates was observed for norfloxacin and imipenem, corresponding to 88.46% in each case, and the last administered antibiotics showed moderate resistance. The resistance of P. aeruginosa to imipenem has been observed in more than 60% of similar studies [23, 34]. Additionally, P. aeruginosa showed resistance rates of 50%, 63%, and 75% to meropenem, norfloxacin, and ofloxacin, respectively [24]
Furthermore, the highest resistance rate of the Enterobacter sp. isolates was 62.86% for both chloramphenicol and imipenem. This result is in agreement with the results of a previous study [24]. Moreover, a significant proportion of Acinetobacter sp. (83.33%, 80.65%, and 78.97%, respectively) showed resistance to imipenem, meropenem, and tetracycline. A similar report showed high rates of resistance to almost all tested antibiotics in Acinetobacter spp. [34].
Citrobacter sp. showed high resistance rates towards chloramphenicol (77.82%), tetracycline (66.73%), and norfloxacin (61.11%). This result is in agreement with those reported by Moges et al. [20], Edrees & Al-Awar [43], and Edrees & Banafa [44].
This finding revealed that 64.71% of the P. mirabilis isolates were resistant to ofloxacin and norfloxacin, 58.82% to tetracycline and cefuroxime, and 52.94% to ceftizoxime. This result aligns with the recent finding that the resistance rate of P. mirabilis was 67% for both ofloxacin and norfloxacin [25]. Additionally, 82.35% of the P. mirabilis isolates from this study exhibited sensitivity to meropenem and imipenem. These results are in agreement with previous reports showing that Proteus sp. had a sensitivity rate of 60.2% and 53.3% for meropenem and imipenem, respectively [34]. Currently, meropenem has been found to be the most effective antibiotic against Proteus sp. at a sensitivity rate of 100% [45].
The rationale behind The disparity in susceptibility or resistance of bacterial isolates can be attributed to the extent to which these isolates are subjected to factors that result in the emergence of resistance. These include the indiscriminate administration of antibiotics for extended periods without requiring medical guidance. Furthermore, low health standards, poor drug quality, the fact that physicians have issued unnecessary antibiotic prescriptions without conducting adequate susceptibility testing on bacteria, and the rapid and uncontrolled use of antimicrobials in agriculture and farming have all contributed to the escalation of this issue.