Acinetobacter baumannii (A. baumannii) is a Gram-negative bacterium that is commonly found around us. This bacterium often causes nosocomial infection around the hospital which happens to 2-10 percent of all nosocomial infections caused by a Gram-negative bacterium. The symptoms of infection include immune disorders for those who are admitted to the hospital for some time. It may also infect the patients undergoing surgical procedures or other chronic diseases. Its ability to grow in various environments with simple nutrition is a key factor in its pathogenesis. A. baumannii may cause bacteremia, ventilator-associated pneumonia, urinary tract, skin, and soft tissues infections, burn and surgical wound infections, osteomyelitis and meningitis. The bacterium may easily enter the body through an open wound, mechanical ventilator, and catheter. The death rate for bacteremia caused by A. baumannii is high with an estimated 30-40 percent.
Carbapenems (imipenem, meropenem, and doripenem) are considered effective antibiotics for A. baumannii infection. The irrational antibiotic prescriptions of carbapenem cause the increasing bacterial resistance to carbapenem, including A. baumannii. Antibiotic resistance caused by A. baumannii infections is hard to treat. The prevalence of carbapenem non-susceptible A. baumannii (CNSAB) is increasing worldwide, including in Indonesia. The main resistance mechanism of CNSAB is to produce beta-lactamase enzymes. Beta-lactamases that possess versatile hydrolytic capacities and therefore can hydrolyze carbapenems are called carbapenemases. Carbapenemases that are commonly found are also known as oxacillinase (OXA). However, A. baumannii naturally has OXA-51. This causes the bacterium gets easily resistant to carbapenemases. The other types of carbapenemases are OXA-23-, OXA-40/24, and OXA-58. OXA-23 enzyme is the most common cause of nosocomial infection outbreaks. The other beta-lactamase commonly found in A. baumannii carbapenem resistance is imipenemase (IMP), Verona integron-encoded Metallo-β-lactamase (VIM), Seoul imipenemase (SIM), and New Delhi Metallo-β-lactamase (NDM).
In this study, the sample was collected from blood cultures of patients treated in various hospitals and tested in the Clinical Microbiology Laboratory. At the national level, there has been 110 A. baumannii bacterium confirmed.
Among 110 isolated A. baumannii bacteria, the result of the test towards antibiotics shows the three antibiotics with the lowest resistance, are Tigecycline, Cotrimoxazole, and Amikacin. The most common type of carbapenemase gene, apart from OXA-51, is OXA-23 (83.6%) and OXA-24 (37.3%). The high prevalence of this gene indicates that A. baumannii is resistant to carbapenems, while there are very few choices of antibiotics to treat patients caused by these bacteria.
The result shows that the highest number of isolated A. baumannii were in RSUD Dr. Soetomo Surabaya, followed by RS Dr. Saiful Anwar Malang, and RSUP Persahabatan Jakarta. These 3 hospitals are type A hospitals with a large number of beds.
The question is, why do many A. baumannii develop resistance to carbapenem. This is presumably due to the irrational use of carbapenem antibiotic prescriptions. The high case of carbapenem-resistant bacteria, occurring in tertiary referral hospitals, is understandable. As these patients are referral patients from various secondary referral hospitals, which are thought to have received a lot of antibiotics, including the carbapenem group.
It is important to prevent bacterial resistance to carbapenem. The first attempt is an appropriate use of antibiotics which are only used when a patient acquires a serious infection that needs carbapenem according to clinical microbiology. Second, it is important to prevent the resistance by raising awareness of hand hygiene by washing hands using antiseptic soap post-contact with the patient or their surroundings in the hospital. Hopefully, with mutual efforts and understanding, we can provide good, effective, and economical infectious disease services.
Author: Prof. Dr. Kuntaman, dr., MS., SpMK(K), Professor of Medical Microbiology
Faculty of Medicine Universitas Airlangga
