|Year : 2017 | Volume
| Issue : 6 | Page : 25-27
Prevalence and outcomes of colistin-resistant Acinetobacter infection in Saudi critical care units
Critical Care Department, King Fahad Hospital, Madinah, Saudi Arabia
|Date of Web Publication||23-Nov-2017|
King Fahad Hospital, Madinah
Source of Support: None, Conflict of Interest: None
Acinetobacter baumannii is a common healthcare associated problem. It can cause a wide variety of nosocomial infections because of its tremendous ability of acquiring antibiotic resistance and to survive in hospital environments. It's associated with high morbidity and mortality. So it has been considered as one of the dangerous organisms by the Infectious Diseases Society of America. In Saudi Arabia, many studies highlighted the magnitude of Acinetobacter baumannii infections but most of the studies were small. We plan to conduct a large multicenter prospective study in major ICUs in Saudi Arabia to determine the prevalence and prognosis of Acinetobacter baumannii infection, resistant pattern, risk factors associated with resistant and outcomes.
Keywords: Acinetobacter baumannii, intensive care, prevalence, risk factor
|How to cite this article:|
Kharaba A. Prevalence and outcomes of colistin-resistant Acinetobacter infection in Saudi critical care units. Saudi Crit Care J 2017;1, Suppl S2:25-7
|How to cite this URL:|
Kharaba A. Prevalence and outcomes of colistin-resistant Acinetobacter infection in Saudi critical care units. Saudi Crit Care J [serial online] 2017 [cited 2021 Oct 27];1, Suppl S2:25-7. Available from: https://www.sccj-sa.org/text.asp?2017/1/6/25/219134
| Introduction|| |
Acinetobacter baumannii is a major hospital-acquired pathogen. It can cause a wide variety of infections affecting the respiratory tract, bloodstream, surgical sites, and urinary tract. Acinetobacter species were first described in 1911, as Micrococcus calcoaceticus by Beijerinck. Acinetobacter species are Gram-negative coccobacilli which can be found in water, soil, and sewage, but they have also been isolated from food and the environment. Currently, the genus Acinetobacter contains more than 30 formally named species. Three among the Acinetobacter species; Acinetobacter baumannii, Acinetobacter nosocomialis (genospecies 13TU), and Acinetobacter pittii (genospecies 3) are considered the most important and they form the “Acinetobacter baumannii complex.” Acinetobacter baumannii accounts for more than 80% of all Acinetobacter species infections.
| Resistance Mechanisms|| |
The organism possesses the tremendous ability of acquiring resistance to most antimicrobial agents, and some strains are resistant to nearly all β-lactam antibiotics, quinolones, and aminoglycosides.
Documented mechanisms of resistance include inherent antibiotic resistance, efflux pumps, antimicrobial-degrading enzymes, decrease permeability, target modification, and porin deficiency.
Resistance to carbapenems is mostly mediated by serine oxacillinases (OXAs) and metallo-β-lactamases (MBLs). MBLs mediate resistance to β-lactamases and carbapenems except for aztreonam. There are different mechanisms of resistance to carbapenems in baumannii and non-baumannii Acinetobacter species. Resistance in Acinetobacter baumannii is mostly mediated by OXA production; whereas MBL production mediates resistant in non-baumannii Acinetobacter isolates. In Saudi Arabia, many studies have shown widespread of carbapenem-resistant Acinetobacter baumannii. Most of the Acinetobacter isolates carry blaOXA-23 gene and a VIM-type metallo-β-lactamase. Moreover, most of the Acinetobacter baumannii in Gulf country hospitals are OXA-23-type producers.
The development of resistance to colistin among Acinetobacter baumannii is alarming and is on the rise. Since colistin-resistant Acinetobacter baumannii was first reported in 1999, the numbers of reports worldwide have increased. SENTRY Antimicrobial Surveillance from 2001 to 2011, revealed low rates of colistin-resistant level (0.9%–3.3%). Other reports from Asia, Europe, North America, and South America revealed rates approaching 7%. However, two reports from Bulgaria and Spain showed even higher rates 16.7% and 19.1%, respectively. Indeed, the highest two reports of colistin-resistant Acinetobacter baumannii came from Spain and Korea with 40.7% and 30.6%, respectively. In Saudi Arabia, Abeer et al. reported colistin-resistant rate of 1.8% among Acinetobacter baumannii isolates that increased up to 4.7% over two years. Surprisingly, another report from 12 hospitals in Jeddah showed no Acinetobacter baumannii resistance to colistin.
Acinetobacter baumannii has unique mechanisms of resistance to colistin than other Gram-negative pathogens. Two main hypotheses have been postulated to explain resistance to colistin; the loss of lipopolysaccharide hypothesis and the PmrAB two components system mediated hypothesis. Furthermore, the previous uses of colistin and quinolone have been postulated to increase the risk of colistin-resistance.
| Prognosis|| |
Acinetobacter baumannii can cause a wide variety of infections. Most of the cases involve the respiratory tract followed by blood, central venous system, and wound infections. A recent antimicrobial surveillance in the US hospitals showed that most Acinetobacter isolates (57.6%) were from the lung, followed by bacteremia (23.9%) and wound infections (9.1%).Acinetobacter species account for 8.4% of ventilator-associated pneumonias and about 2.2% of catheter-related bloodstream infections in the US.
Approximately 65% of pneumonias caused by Acinetobacter baumannii in the US and Europe are carbapenems resistance. Similarly, most of the Acinetobacter baumannii isolates in Saudi Arabian hospitals were from respiratory tract followed by the bloodstream. Diabetic patients have higher rate of resistance to carbapenems. Immunosuppression and admission to the Intensive Care Unit (ICU) with invasive procedures such as endotracheal intubation and central venous catheters are associated with higher risk of nosocomial Acinetobacter infections.
Mortality rate of Acinetobacter baumannii infection is high, especially with carbapenems resistant strains. Mortality rate was 52% in patients with bacteremia and 23-73% in those with pneumonias. Another study suggested that infections with Acinetobacter baumannii were associated with higher mortality than non-Acinetobacter baumannii infections. Many prognostic factors have been identified, but age, the severity of illness; solid organ transplant, underlying malignancy, prolonged ICU stay, and inappropriate antimicrobial therapy are associated with worse prognosis. Not surprisingly, Acinetobacter baumannii has been considered by the Infectious Diseases Society of America among the top dangerous pathogens responsible for high morbidity and mortality.
| Research Gaps|| |
Understanding of mechanisms of résistance remains limited. In Saudi Arabia, many studies have been conducted addressing Acinetobacter baumannii prevalence, clinical presentation and risk factors associated with resistant but most of the studies were small, single center, or regional study. There is no large multicenter study addressing this National Health Problem. At national level, we need to address the prevalence and clinical presentation, risk factors associated with resistant, prognosis, and management of patient with colistin-resistant Acinetobacter species including outbreak control [Table 1].
|Table 1: Research gaps in current knowledge regarding colistin-resistant Acinetobacter species|
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In conclusion, the incidence of colistin-resistant Acinetobacter infection is increasing. Despite the perception of a large number of Acinetobacter infection, the prevalence and prognosis of colistin-resistant Acinetobacter baumannii in Saudi Arabia are unknown. A large multicenter cohort study in Saudi ICUs is urgently needed to determine the burden of the illness at a national level.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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