In our study, all the HAIs were associated with the use of invasive devices and majority (92%) of the patients were admitted in ICUs.
VAP comprised majority (69%) of the infection followed by CAUTI (21%) and CLABSI (20%).
The WHO quotes that the risk of acquiring HAIs is significantly higher in intensive care units (ICUs), with approximately 30% of patients affected by at least one episode of HAIs. The present study was carried out exclusively in ICU setup.
The pattern of distribution of diseases in our study was similar to multiple prior published studies. U.S National Nosocomial Infection Surveillance system reports that three major infection sites comprised 68% of all reported infections; nosocomial pneumonias were most frequent, followed by UTIs and primary bloodstream infections (BSIs), and the vast majority of infections were associated with the use of invasive devices (87% of primary BSIs, 83% of nosocomial pneumonias, and 97% of UTIs were associated with central intravenous lines, mechanical ventilation, and urinary catheter respectively).
In a prospective observational study by Habibi et al, pneumonia (77%) was the most common infection followed by UTI (24%) and bloodstream infection (24%).
Pooled rates of VAP, CLABSI, and CAUTI were 9.4/1,000 mechanical ventilator–days, 5.1/1,000 central line–days, and 2.1/1,000 urinary catheter–days respectively, as reported by International Nosocomial Infection Control Consortium from India.
Majority of the patients in our study were young and belonged to 18-30-year age group category (36% overall; 34.8% in VAP, 50% in CLABSI, and 33% in CAUTI). This is contrary to the common finding; that age > 60 year predisposes patients to develop HAI and can be attributed to the varying population characteristic. [4, 8, 9]
When examining gender distribution, males (61) were more common than females (39) in our study. Gender of the patient per se does not have a strong correlation with increased risk of HAI overall as seen in EPIC II study and many other Indian studies. [3, 10, 11] However, when breaking down the infection into VAP and CAUTI, male gender has been demonstrated to be a risk factor of VAP and female gender likewise for development of CAUTI.
Cook et al in their seminal paper published on risk factors of VAP showed higher proportion of male gender afflicted with VAP. Similarly, Rello et al in their large epidemiological study published on VAP showed that male gender was strongly correlated with development of VAP. Whether this is causal or correlational is still unknown; however, higher proportion of males smoke in India and are thus predisposed to the development of COPD in comparison to females. This could possibly offer an explanation for higher incidence of VAP in males in our study.
Nineteen percent of patients in our study who developed CAUTI were females. Female gender is a non-modifiable risk factor for development of CAUTI. Female patients are susceptible to developing CAUTI, owing to the differences in urethral anatomy, with female urethra being relatively short and wide with straight path into the bladder, making it easy for bacterial entry.
Organisms isolated and Antibiotic sensitivity profile
A total of 76 pathogens were isolated on culture and accounted for the nosocomial infections in these patients. Majority (92%) were gram-negative organisms and only 8% were gram-positive. All of the isolated organisms were multidrug resistant. The global scenario shows that gram-positive infections are more prevalent in the Western world ICUs. However, gram-negative bugs dominate in India and Asia-Pacific region.[3, 7, 15] In Asian ICUs, gram-negative isolates constituted 74% as compared to 58% in Western Europe, while gram-positive isolates constituted 34% in Asian ICUs and 49% in Western Europe. Our findings are in corroboration with the other worldwide studies. The National Nosocomial Infections Surveillance System reported a significant increase in the proportion of Acinetobacter among all gram-negative aerobes during the 17 years of the study period. Acinetobacter was also the predominant (39.5%) causative organism in our study.
Resistance shown by organisms from developing countries are higher than in developed countries, which is clearly proven in our study. Study from China, analyzing the resistance rate of Acinetobacter baumannii and Pseudomonas aeruginosa, showed that the resistant rate of Acinetobacter baumannii to Meropenem has increased from 32–83% in the last 10 years, for piperacillin/tazobactam it has increased from 44.8–78.4%. The resistance rate of P. aeruginosa to imipenem has been increasing as well, which was 30.3% in 2006 and 45.6% in 2015. High resistance rates have been reported by adult and pediatric ICUs from 40 hospitals in 20 cities of India to International Nosocomial Infection Control Consortium.Numerous studies from developing counties including India show the same of high levels of sensitivity to colistin and high levels of resistance to broad spectrum antibiotics [6, 11, 18]. Our study shows similar findings. In Ghanshani et al study, all Enterobacteriaceae and pseudomonas were ≥ 95% sensitive to colistin, Klebsiella and Pseudomonas were > 50% resistant to 3rd generation cephalosporin and carbapenems, while E. coli was still > 50% sensitive to carbapenems and Acinetobacter > 50% sensitive to 3rd generation cephalosporin. Gram-positive organisms showed zero sensitivity to penicillin, oxacillin, and tetracycline. MSSA were 100% sensitive to vancomycin, and 50% sensitive to linezolid and gentamycin. Enterococcus was 100% sensitive to linezolid, 50% sensitive to vancomycin. In Dutta et al study Staphylococcus aureus and Enterococcus were 100% sensitive to linezolid and vancomycin and more than 50% resistant to gentamicin, erythromycin, and ciprofloxacin. Similar findings were seen in Ghanshani et al study.
Our study and numerous studies worldwide are in concordance. Indiscriminate use of antibiotics for prolonged and inappropriate duration is the possible explanation of such high levels of multidrug resistance in the organisms.
Limitations of the study
The sample size of the study was small, therefore statistical power of the study is low.
Our study cannot give information on anaerobic and fungal causative pathogens of HAI as no special culture techniques were employed to isolate them.
High mortality seen in our study could be due to the severity of the disease they were admitted with and also due to lack of state-of-the-art ICU care.