VAP is one of the prevalent infections with high mortality in patients hospitalized in ICUs of hospitals in most parts of the world. In this study, the most MDR isolated pathogens were Acinetobacter Baumannii and Pseudomonas aeruginosa. And the highest antibiotic sensitivity was observed in gram negative cases against ciprofloxacin, meropenem and imipenem, and in gram-positives against linezolid and ciprofloxacin. The mortality rate in this study was 38%.
The prevalence of VAP in different regions is different according to several studies conducted [4, 8, 9]. However, the incidence of VAP in Asian countries is similar to the European countries. In the present study, it became clear that the incidence of VAP is lower in educational hospitals of Shiraz (especially Namazi). The reasons for the low incidence of pneumonia in Namazi Hospital in the intensive care units in comparison with the Asian countries, are as follows: 1- In the ICU of Namazi Hospital, the ratio of the number of nurses to the number of patients is 1:1, while in a study in India [10], the ratio has been 3:17. 2- Nemazi Hospital has an active infection control committee and highly emphasizes the health of the personnel, especially washing the hands. 3- Care and protection of patients is done very carefully and patients are suctioned in a timely manner. 4. Traveling in ICU is prohibited, and patients do not associate with anyone else except the nurse and doctor. In general, the more standard become the interventions performed on hospitalized patients, and the more modern are the designs of the physical conditions of the hospitals to prevent VAP in a more modern form, the lower will be the frequency of having VAP.
Determining the factors that affect mortality extent will provide a better prognosis [11]. In our study, 45% of the patients with VAP received antibiotics before the incidence of pneumonia, of which 31.6% died. While of the remaining 54.8%, only 8.7% died. In other words, patients who received antibiotics before the incidence of pneumonia had higher mortality. On the other hand, the most common microorganisms isolated from patients were Acinetobacter (28.8%) and Pseudomonas (18.6%) that were considered as part of MDR pathogens. Probably, the antimicrobial treatment prior to the onset of VAP has led to the selection of these MDR pathogens [12]. The most common pathogens in our study were Acinetobacter Baumannii (28.8%) and then Pseudomonas aeruginosa (18.6%). In general, the incidence of Acinetobacter in Asian countries is higher than other European countries. While the incidence of MRSA and P. aeruginosa in Asian countries is lower than the values reported in European countries [13]. The reason for the high incidence of Acinetobacter infection in Asian countries is not clear, but it may be due to temperature and humidity differences, because the warmer the environment and the higher the moisture, the more ideal become the conditions for the growth of Acinetobacter [14].
In this study, the mortality rate for the 20 individuals who received inappropriate experimental treatment was 23.4% and for the 27 subjects who received appropriate experimental treatment, it was 14.9%. P. value was less than 0.05. Therefore, there is a significant relationship between the quality of treatment and mortality. Several clinical studies have shown that experimental treatment of VAP with an appropriate antimicrobial regimen is associated with lower mortality [15-17]. In other words, the failure of antibiotic treatment is due to the presence of MDR pathogens [18]. In the prospective study by Fabrice Michel et al. [6] and also in the retrospective study of David L. Green [19], the patients whose experimental antibiotic therapy has been inappropriate, the changes in antibiotics after providing the culture response have not diminished the extent of mortality. In this study, patients who had received inappropriate experimental treatment had a higher mortality, however, this issue should also be taken into consideration that these patients had a critical condition of disease at the admitting time. Therefore, it cannot be properly demonstrated that inappropriate experimental treatment of hospital pneumonia has increased their mortality or is associated with their critical condition.
This finding show, overall 70.6% of the isolated Acinetobacters were sensitive to Meropenem and 76.5% of them were sensitive to amikacin, and in other words, they are the best coating for Acinetobacters. In the case of Pseudomonas, the highest susceptibilities were observed for meropenem, imipenem and ciprofloxacin (90, 80, 70%) and appear to be the best treatment against this bacterium. Meropenem seems to be the best coating for both bacteria. Also in our study, the sensitivity of gram-positive bacteria against linezolid was (100%). However, it is better to use vancomycin for treatment because linezolid is an alternative drug for treating VAP resulting from MRSA. Therefore, it is recommended that in the experimental treatment for MRSA treatment, vancomycin be used, which is considered the standard treatment for MRSA, and linezolid be stored for specific cases. Our data showed that most isolates (57%) were related to MDR pathogens. The most common organisms in the last study in Shiraz, were Acinetobacter Baumannii, MRSA, and in the third place, the Pseudomonas aeruginosa, but in our study, Pseudomonas aeruginosa was ranked second.