Molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii in a university hospital in Italy

Abstract

This study investigated the molecular epidemiology of a clonal outbreak of multidrug-resistant Acinetobacter baumannii that occurred between June 2003 and June 2004 in a tertiary-care hospital in Naples, Italy. A. baumannii was isolated from 74 patients, of whom 38 were infected and 36 were colonised. Thirty-three patients had ventilator-associated pneumonia, three had hospital-acquired pneumonia, and two had sepsis. Genotypic analysis of 45 available A. baumannii isolates revealed two distinct pulsed-field gel electrophoresis (PFGE) patterns. Of these, PFGE pattern 1 was represented by isolates from 44 patients and was identical to that of an epidemic A. baumannii clone isolated in another hospital of Naples during 2002. All A. baumannii isolates of PFGE type 1 showed identical multiresistant antibiotypes, characterised by resistance to all antimicrobial agents tested, including carbapenems, with the exception of colistin. In these isolates, inhibition of OXA enzymes by 200 mM NaCl reduced the imipenem MIC by up to four-fold. Molecular analysis of antimicrobial resistance genes showed that all A. baumannii isolates of PFGE type 1 harboured a class 1 integron containing the aacA4, orfX and bla(OXA-20) gene cassettes, an ampC gene and a bla(OXA-51)-like allele. Moreover, a bla(OXA-58)-like gene surrounded by the regulatory elements ISAba2 and ISAba3 was identified in a 30-kb plasmid from A. baumannii isolates of PFGE type 1, but not PFGE type 2. Thus, selection of a single A. baumannii clone producing an OXA-58-type carbapenem-hydrolysing oxacillinase was responsible for the increase in the number of A. baumannii infections that occurred in this hospital.

Antimicrobial Resistant Determination and Prokaryotic Expression of smpA Gene of Acinetobacter baumannii Isolated from Admitted Patients

“…Recently progressive significant increasing of antibiotic resistance in A. baumannii isolates, created a serious threat to hospitalized patients (6,(8)(9)(10)(11). In our study, in around 45% of isolates A. baumannii was diagnosed, the majority of studied patients were hospitalized in the ICU and most samples were isolated from the sputum cultures (50%).…”

“…The above mentioned properties of these species and the emerging antibiotic resistance for A. baumannii, could be related to biofilm formation. Outer membrane proteins (OMPs) are the plentiful surface proteins of this organism cause of nosocomial infections (6,(9)(10)(11)(12)(13)(14)(15). The most important way for restriction of infectious diseases is vaccination.…”

<i>Acinetobacter</i> multirresistente – um desafio para a saúde pública

“…Outro estudo realizado na Itália relacionou o aumento da resistência aos carbapenêmicos e a ocorrência de surtos à presença do gene bla oxa-58 tanto em isolados de pacientes infectados como colonizados. 37 Uma característica importante que tem sido descrita é a emergência de cepas PAN-R associadas a surtos. A multirresistência pode ser definida como a resistência a pelo menos três classes de antimicrobianos, enquanto a pan-resistência tem sido definida como resistência a todas as classes de antimicrobianos normalmente utilizados no tratamento.…”

“…Entretanto, quando relatamos surtos mais amplos, com disseminação entre hospitais de uma mesma cidade ou país, a disseminação está associada a um determinante de resistência que se propaga entre diferentes cepas. 22,25,[28][29][30]32,35,37,44 …”

Pulsed-Field Gel Electrophoresis (PFGE) standardization protocol for Proteus mirabilis

“…Epidemiyolojik sürveyans ve olası bir salgınla ilişkili suşlar arasındaki klonal ilişkiyi araş-tırmada farklı moleküler tipleme yöntemleri denenmektedir [11,13,16]. Bunlar arasında ayrım gücü en yüksek olan "pulsed-field jel elektroforezi (PFGE)" yöntemidir [12,13,17]. Altın standart olarak kabul edilen bu yöntemin, en önemli dezavantajı, farklı laboratuvarlarda değişik protokollerin uygulanması nedeniyle sonuçların birbirleriyle kıyaslanma olanağının olmamasıdır.…”