Human immunodeficiency virus (HIV) associated immunosuppression increases the vulnerability of patients to various infections [1]. Enteric bacterial pathogens such as Salmonella species, Campylobacter species, Shigella species, Clostridium difficile and different strains of Escherichia coli have been identified as etiologic agents with the potential to cause severe illness in HIV-infected patients [2, 3]. Symptoms, duration and potential for severe manifestations of enteric bacterial infections are influenced by many factors including immunity status (measured by CD4+ T cell count) and the use of highly active antiretroviral therapy (HAART) and prophylaxis. Previous research showed that patients with lower CD4+ T cell counts are more likely experience bacterial diarrhea [4]. Bacteremia due to Salmonella, Campylobacter and Shigella was also more common in those with lower CD4+ T cell counts [5, 6].

Gastrointestinal tract (GIT) illnesses such as diarrhea affect up to 95% of persons with AIDS, frequently causing malabsorption, significant weight loss, higher rates of extra-intestinal infections, and increased mortality in developing countries [7]. The introduction of HAART and prophylactic management of opportunistic infections has brought substantial improvements in health and life expectancy of PLHIV. Several reports from developed countries have shown the decline in diarrheal episodes (specifically bacterial diarrhea) [4, 6]. However, these protective roles of HAART were not demonstrated in some other studies [3, 8].

An increasing rate of bacterial resistance to drugs commonly used to treat enteric infections further complicates the management of disease in PLWHIV. Due to the frequent exposure to antibiotic therapy and prophylaxis, HIV-infected patients might carry resistant bacterial strains [9]. In some studies, enteric bacterial pathogens with higher rate of resistance to antimicrobials were isolated from PLWHIV [10, 11].

In Ethiopia, information about the epidemiology of enteric bacterial pathogens in PLHIV is scant. A study that investigated HIV-infected patients in the southwest part of the country (Jimma) during the pre-HAART period showed bacterial pathogens such as Salmonella, Shigella, Campylobacter and E. coli were common [12]. In the same study, isolates were found to be less sensitive to tetracycline, chloramphenicol, gentamicin, and nalidixic acid. The present study aimed to identify bacterial pathogens and their antibiotic susceptibility pattern among HIV-infected patients attending a largest hospital in southern Ethiopia. The findings of this study will help generate evidence to inform antimicrobial stewardship efforts, and provide location –specific comparator information for similar studies undertaken in other populations.

A compromised immunity resulting from HIV infection hampers the intestinal defense against microbes. Consequently, enteric bacteria are common and more likely to cause diarrhea and other invasive conditions in HIV-infected patients than healthy individuals [13]. The rate of enteric bacterial isolates in the present study was shown to be 12.6%. A similar rate (16%) was reported in a previous study in southwest Ethiopia (Jimma) [12], and other settings outside Africa, including Cambodia (12.5%) [14] and Peru (14.5%) [2]. Rates reported in Uganda (19.2%) [15] and India (29%) [16] were higher than our findings. The rate of bacterial isolation among patients with diarrhea (22.5%) in the current study was comparable to findings in Peru (22%) [2], Thailand (17.4%) [17], and Uganda (21%) [15] but lower than rates reported from India (44%) [16] and South Africa (43.3%) [18]. The observed differences in rates of bacterial isolation could be attributed to differences in risk factors in various populations. The number of patients with diarrhea included in different studies could also affect the rate of enteric bacterial isolates as it was shown in the present study that majority of the pathogens (80%) were isolated from those patients who reported having diarrhea.

The predominance of Campylobacter species in the present study was similarly reported in South Africa [18] and England [3] although this bacterium was not isolated in other studies that employed similar laboratory technique [14, 16]. The rates of Campylobacter species in Uganda (3.5%) [15], in Peru (1.7%) [2], and in Brazil (1%) [19] were shown to be lower than our observation. The rate of Salmonella infection (5.1%) in the present study was higher than a finding in Peru (1%) [2], but lower than a result from Uganda (8.1%) [15]. The rate of Shigella species (1.3%) was also comparable with findings in India (1%) [16] and Cambodia (1.3%) [14], but lower than a result in Uganda (9.5%) [15]. The predominance of S. flexineri was consistent with results in Thailand and USA [4, 17]. Similar to the studies reported elsewhere [17, 20], only EHEC strains (O26:H11 and O48:H21) was identified in the present study even if reports [19, 21] on other strains of E. coli were also documented.

The occurrence of enteric bacterial infection in HIV-infected individuals is thought to be the net effect of socio-demographic as well as clinical status of the infected patients. Factors like hand washing practice, contact with pet animals, consumption of raw food and others have been indicated as potential factors for acquiring enteric bacterial infection [22]. In the current study, only a habit of consuming raw food was found to increase the odds of having enteric bacterial pathogens.

It was previously reported that a higher rate (80%) of enteric bacterial isolates among patients with CD4+ T cell count <200 cells/mm³ [4]. In contrast, the current study showed no significant difference in the rate of bacterial isolates among patients with CD4+ T cell count above and below 350 cells/mm³. Similar finding was reported in a study from England where 65.6% of the isolates were detected among patients with CD4+ T cell count >350 cells/mm³ [3].

The role of HAART in protecting against enteric infection through inhibition of viral replication and restoring immunity has been well documented [23]. However, the absence of association between the rate of isolation and HAART status in this study may be due to the frequent exposure of people living in poor hygienic condition to enteric bacterial infection that possibly diminishes the protective role of HAART in the present study participants. The limited effect of HAART in restoring GIT immunity was also reported [24].

Globally, increased bacterial resistance to antimicrobial agents is raising a significant concern for public health. The study showed that most bacterial isolates were resistant to tetracycline, SXT and chloramphenicol. Resistance is likely to have developed due to the unrestricted, frequent and inappropriate usage of antimicrobials in the study area. These drugs are commonly used for empirical treatment (SXT and chloramphenicol), as prophylactic before and after surgery (chloramphenicol together with other agents), and patients’ own self-medication (SXT and tetracycline) [25]. The present study showed that most of the isolates were sensitive to nalidixic acid, gentamicin, norfloxacin, ceftriaxone and ciprofloxacin.

Our study faces several limitations. First, as for any hospital-based study, our sample may have lacked representativeness and results may not be generalizable to all HIV-infected population in the study area. Second, the small sample size of the study likely limits its power.

This study showed that enteric bacterial pathogens were common among HIV-infected individuals, particularly in those who experienced diarrhea. Campylobacter and Salmonella species were the predominant isolates. The observed significant association between consumption of raw food and enteric bacteria pathogens may hint at the importance of ingesting adequately cooked food to prevent infection. Most isolates were sensitive to nalidixic acid, gentamicin, norfloxacin, ceftriaxone and ciprofloxacin and a high proportion were resistant to SXT and chloramphenicol. The need to strengthen antimicrobial stewardship efforts should be emphasized to slow grown antimicrobial resistance among this population group.