Despite progress in modern medical techniques and clinical application of various surgical operations, nosocomial infections (NIs) is considered as a major risk factor for the prognosis of patients .It is also notable that, NIs might not only be, directly or indirectly, the critical cause the death of patients, but also directly affect the treatment or operation of the patients and prolong their hospitalization. The primary objective of present study was investigate the rate of nosocomial infections (NIs) in two type of ICU (internal and medical surgery), and analysis the related risk factors NIs we observed that, infection (positive culture) incidence between internal ICU and MS-ICU was 27.2% and 10.2%from 2015 to 2016, respectively. Previous studies have demonstrated that, the suffering of infection in the internal ICU was greater than the MS-ICU, which was significant [7, 9, 10–12].
In addition, we observed that, a variety of risk factors may be associated with the occurrence of NI such as the length of stay and use of medical devices (NG tube and ventilator). Therefore, we should pay more attention to the affecting factors of the patients in ICU, who are known as the group with the high risk of NI. In our study, we demonstrated that, the mean of length stay of internal ICU and MS-ICU was 8.73 ± 7.46 and 8.11 ± 4.8 days, respectively. There was a significant relationship between the length of stay two ICUs and infection (p-value < 0.001).Also, there was no significant difference between the two groups in terms of age and gender; however, a relationship between age and the rate of infection was significant (p-value < 0.001). Ott et al. have revealed that, length of ICU stay was as one factor in occurrence of infection in internal ICU . Increasing the length of stay in the ICU, both spontaneously and through the longer usage of ventilator and NG tube, can be considered as a factor in increasing internal ICU infections compared to surgery.
Moreover, in our study and other studies [10, 11, 13, 14–16], there was a direct relationship among the age, length of ICU stay, duration of catheterization, and infection, so that in both ICUs, this relationship was significant(p-value < 0.001), if the most common type of infection were UTI and RTI in each of ICUs. The presence of underlying diseases in internal ICU patients can be one of the causes of more infections in this group. In our study, in internal ICU, hypertension (41.1%) was found to be the most common underlying disease followed by the chronic lung disease (22.1%), Diabetes (16.7%), and heart diseases (16.4%). While hypertension (31.1%) was the most common underlying disease followed by heart disease (23.5%), chronic lung disease (21.1%), and cancer (17.0%) at surgical ICU (Table1). In this regard, underlying disease can cause people become more susceptible to further infection, as well as to the dangerous non-common pathogens, due to cellular immune deficiency and the increased susceptibility to infection, along with the need for long-term hospitalization for sugar control and also the need for broad-spectrum antibiotics .
In our study, we found that, the most common infections in internal ICU were RTI and UTI 46.9% and 37.5%, respectively. On the other hand, the most common infections in MS-ICU were RTI (38.3%) and RTI&SSI (22.0%), respectively. High prevalence of RTI and pneumonia in both ICUs in our study and other studies is due to the long-term patient's intubation. All of the patients (100%) have mechanical ventilation, and in addition to the infection caused by intubation; aspiration pneumonia and nosocomial pneumonia can also be named. In a preview study, The most common infection in both ICUs was pneumonia followed by UTI and septicemia and SSI, respectively [11, 18, 19]. In this regard, we demonstrated that Candida spp. was the most frequent isolated pathogens for UTI, and Pseudomonas aeruginosa was the most common pathogens for RTI, BSI, and SSI. In MS-ICU E.coli was the most isolated pathogens for UTI, Pseudomonas aeruginosa was the most common pathogens for RTI, and Staphylococci and Klebsiella spp. were responsible for most of the BSI and SSI (Fig. 2). According of other studies Pseudomonas aeruginosa was the most common pathogens that isolates from variety samples in ICU patients, followed by Staphylococci, Klebsiella, E.coli were as the common agents of infection [7, 20, 2].
Notably, the incidence of NI in internal ICU (27.2%) was significantly more than MS-ICU (10.2%). In this regard, we should pay more attention to the influencing factors of critical patients who admitted in internal ICU. In our study, we found that rate of infection, length of ICU stay and used of NG tube were related with NIs rate in surgical ICU. However, age, the length of ICU stay, underlying disease, used of NG tube and ventilator were factors associated with NIs rate in internal ICU. In terms of mortality, 62.5% of the patients in the internal ICU had positive culture and 48.4% had no infection, and in the ICU surgery 39.7% of the patients had positive culture and 14.3% had no infection, which was a significant difference (p-value < 0.001). In a preview studies showed that, NIs rate with increasing of infection (positive-culture) in internal ICU had a significant difference [22–26] Therefore, we should be undertaken to monitor and reduce the affecting factors of the patients in ICUs, who are known as the group with the high risk of NI.