Investigation of Acinetobacter baumannii Outbreak in a Burn Unit Revealed a Surprising Environmental Source

We describe an outbreak of Acinetobacter baumannii in a 15-bed regional burn unit in an academic tertiary care medical center, and the investigations and control measures used to halt the outbreak are described. Nine cases of A. baumannii were reported in our burn unit in a one-year period, which was higher than our expected number of two-three cases per year. Our burn unit director requested an outbreak investigation, and our hospital's infection control department investigated thoroughly and found a source for that outbreak, which was never reported as a source in the previous literature. We identified table fans as the source of this outbreak. We then developed a strict fan policy, and after implementation of the policy, and terminal cleaning of rooms, only two cases per year of A. baumannii were reported in the next three-year period. We concluded that the table fans were colonized with A. baumannii and since they were used interchangeably in all patient rooms, caused this outbreak. There are no specific joint commission guidelines for the use of fans in hospitals. While fans can be used for the comfort of the patient, we should be cautious not to spread infections.

Multidrug-resistant Acinetobacter baumannii infections: looming threat in the Indian clinical setting

INTRODUCTION

The recent increase in multidrug-resistant strains of A. baumannii has increased the incidences of ventilator-associated pneumoniae, catheter-associated urinary tract infections, and central line-associated blood stream infections, together increasing hospital stay, treatment cost, and mortality. Resistance genes blaOXA and blaNDM are dominant in India. Carbapenem-resistant A. baumannii (CRAB) International clone-2 (IC-2) are rising in India. High dependency on carbapenems and last-resort combination of tigecycline and polymyxins have aggravated outcomes. Despite nursing barriers, ward closure, environmental disinfections etc for detecting and controlling transmission, MDR isolates and CRAB nosocomial outbreaks continue. Treatment cost overruns by AMR adversely affect 80% of Indians without insurance cover.

AREA COVERED

This narrative review will cover epidemiology, resistance pattern, genetic diversity, device-related infection, cost, and mortality due to multidrug-resistant and CRAB in India. A comprehensive literature search in PubMed and Google Scholar using appropriate keywords at different time points yielded relevant articles.

EXPERT OPINION

It is challenging to enforce policies to control MDR A. baumannii in India. Government and hospitals should enforce stringent infection control measures, surveillance, and antimicrobial stewardship to prevent further spread and emergence of more virulent and resistant strains. Knowledge on antibiotic resistance mechanisms can help design novel antibiotics that can evade, resistance.

The Evaluation of Antibiotic Resistance and nalB Mutants in Pseudomonas eruginosa Isolated from Burnt Patients of Shohada Mehrab Yazd Hospital Burn Ward

Background

Due to extensive damage to the skin, burn victims may acquire life-threatening infections. Though the skin primarily protects against microbial invasions, a large number of bacteria, fungi, and viruses can be isolated from burn patients, specifically Pseudomonas aeruginosa, a gram-negative bacterium with both intrinsic and acquired antibiotic resistance (AR) properties. nalB mutations can be found on the mexR in the P. aeruginosa chromosome. This mutation can induce overexpression of the mexAB-oprMoperon, and affect the MexAB-OprM efflux pump, which removes antimicrobial agents from the bacterial cell. Identifying nalB mutants can be useful for monitoring factors affecting AR.

Methods

In this study, 70 P. aeruginosa isolates identified from burn patients and antibacterial sensitivity was evaluated using the Kirby-Bauer method. We also investigated nalB mutations in samples using molecular methods including Polymerase reaction chain (PCR) and Sequencing.

Results

We identified nalB mutations in 16 isolates. We also found that the increasing effect of nalB mutants induces hyper production activity of MexAB-OprM resulting in AR. Overall, these findings compliment the findings of previous reports.

Conclusion

According to the resistance patterns of the samples, both Amikacin and Ciprofloxacin showed the highest resistance (%). Further, the relationship between Ciprofloxacin resistance and nalB mutations was statistically significant (p= 0.016). The results confirm that the increasing effect of nalB mutants on hyper production activity of MexAB-OprM leads to AR.

Comparative mechanism based study on disinfectants against multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii has emerged as a hospital-acquired pathogen and has spread in the hospital settings, leading to enhanced nosocomial outbreaks associated with high death rates. Therefore, the aim of the current study is to determine the effective concentration of disinfectants like sodium hypochlorite, hydrogen peroxide, and chlorine dioxide, against multidrug-resistant (MDR) strains of A. baumannii. In this study, we have investigated the effect of disinfectants on different MDR strains i.e. RS307, RS6694, RS7434, RS10953, RS122, and sensitive strain ATCC-19606 of A. baumannii, via differential growth curves analysis, disc diffusion assay, estimation of reactive oxygen species (ROS), lipid peroxidation, and protein carbonylation. All the results collectively showed that 1% sodium hypochlorite (P value < 0.0027), 2.5% hydrogen peroxide (P value = 0.0032), and 10 mM (P value = 0.017) chlorine dioxide significantly inhibit the growth of MDR strains of A. baumannii. A significant increase in the ROS generations, altered lipid peroxidation, and a decrease in protein carbonylation was also observed after treatment with disinfectants, which confirmed its ROS-dependent damage mechanism. These disinfectants also enhance the membrane leakage of reducing sugar, protein, and DNA. The current study highlights and recommends the use of 2.5% hydrogen peroxide to control the MDR strains of A. baumannii in the hospital setup. Therefore, the present results will help in selecting concentrations of different disinfectants for regular use in hospital setups to eradicate the multidrug-resistant A. baumannii from the hospital setup.