Pseudomonas aeruginosa as a cause of infections in haematological patients

Pseudomonas aeruginosa je gram-negativan nefermenativan bacil ubikvitarno prisutan u medijima poput tla, vode i vegetacije. Iako posjeduje mnoge čimbenike virulencije, to je oportunistički patogen koji rijetko uzrokuje infekcije u zdravih osoba. Infekcije se javljaju uglavnom u osoba sa oštećenjem kožne ili sluznične barijere uzrokovanim opeklinama, ranama i kirurškim zahvatima, imunokompromitiranih osoba, intubiranih osoba ili osoba sa kateteriziranim mokraćnim mjehurom. Posebna pažnja se pridaje P. aeruginosa kao potencijalnom patogenu u bolnicama budući da se pojavljuje na rizičnim odjelima (hematološki odjeli, odjeli intenzivne skrbi). Svi oblici imunokompromitiranosti mogu predisponirati razvoj infekcije, posebice neutropenija, defekti stanične i humoralne imunosti, cistična fibroza, karcinomi, sindrom stečene imunodeficijencije, dijabetes. Veliki broj zahvaćenih su upravo hematološki bolesnici, posebice oboljeli od akutnih leukemija. Oni mogu razviti infekciju kao posljedicu samog maligniteta ili zbog neutropenije uzrokovane terapijom koja može uključivati kemoterapiju i transplantaciju krvotvornih matičnih stanica. Pseudomonas aeruginosa u tih bolesnika najčešće uzrokuje sepsu i endokarditis. Klinički se bakterijemija uzrokovana s P. aeruginosa ne razlikuje od onih uzrokovanih drugim gram-negativnim bakterijama ali im je smrtnost vrlo visoka te može dosezati i do 50%. U nekim slučajevima javlja se karakteristična kožna lezija - echtyma gangrenosum. Ostali simptomi variraju ovisno o lokalizaciji primarne infekcije. Kod nekih pacijenata, zbog nemogućnosti stvaranja upalnog odgovora, klasični znaci i simptomi infekcije mogu biti maskirani. P. aeruginosa posjeduje veliki broj mehanizama rezistencije što često čini liječenje pseudomonasnih infekcija složenim i dugotrajnim. Zbog sve većeg broja multiplo rezistentnih sojeva nerijetko zahtjeva kombiniranu antibiotsku terapiju.Pseudomonas aeruginosa is a gram-negative non-fermentative bacillus, ubiquitously present in mediums such as soil, water and vegetation. Even though it has many virulence factors, it is an opportunistic pathogen which rarely causes infections in healthy persons. Infections occur in persons with damaged skin or mucosal barrier caused by burns, wounds and surgical procedures, in immunocompromised persons, intubated persons or persons with indwelling urinary catheters. It is important to take notice of P. aeruginosa as potential pathogen in hospitals as it appears in high-risk wards (haematological wards, intensive care units). All forms of immunodeficiency can lead to infections, especially neutropenia, cellular and humoral immune deficiency, cystic fibrosis, cancer, acquired immunodeficiency syndrome and diabetes. Hence, large number of affected are haematological patients, especially the ones who suffer from acute leukaemia. They can develop an infection as a consequence of the cancer itself or because of neutropenia following chemotherapy and stem cell transplant. In these patients P. aeruginosa mostly causes sepsis and endocarditis. It is usually not possible to distinguish between bacteraemia caused by P. aeruginosa and bacteraemia caused by other gram-negative bacteria, but its mortality is very high and can reach up to 50%. In some cases, a characteristic skin lesion develops – echtyma gangrenosum. Other symptoms vary, depending on the origin of infection. Some patients can have masked signs and symptoms of infection due to inability to create inflammatory response. P. aeruginosa has notable intrinsic mechanisms of resistance and is capable of acquiring multiple mechanisms of antibiotic resistance which can make the treatment of these infections long and complicated. Because of the rising number of multidrug-resistant strains, combination therapy is often required