Virulence characteristics of multidrug resistant biofilm forming Acinetobacter baumannii isolated from intensive care unit patients

Abstract

Background Nosocomial infections and persistence of multidrug resistant biofilm forming Acinetobacter baumannii in hospitals has made it as a serious problem in healthcare settings worldwide. Methods A total of 100 A. baumannii clinical isolates from immunocompromised patients hospitalized in ICU were investigated for biofilm formation, the presence of biofilm related genes ( bap, ompA, csuE, fimH, epsA, bla PER-1 , bfmS, ptk, pgaB, csgA, kpsMII ), integron characterization and molecular typing based on REP-PCR. Results All isolates were resistant to three or more categories of antibiotics and considered as multidrug resistant (MDR). A total of 32 isolates were resistant to all tested antibiotics and 91% were extensively drug-resistance (XDR). All isolates were able to produce biofilm and 58% of isolates showed strong ability to biofilm formation. All strong biofilm forming A. baumannii isolates were XDR. All A. baumannii isolates carried at least one biofilm related gene. The most prevalent gene was csuE (100%), followed by pgaB (98%), epsA and ptk (95%), bfmS (92%) and ompA (81%). 98% of isolates carried more than 4 biofilm related genes, simultaneously. Class I integron (67%) was more frequent in comparison with class II (10%) ( P < 0.05). The REP-PCR patterns were classified as 8 types (A-H) and 21 subtypes. The A1 (23%) and C1 (15%) clusters were the most prevalent among A. baumannii isolates ( P < 0.05). According to the REP-PCR patterns, 23% of all isolates had a clonal relatedness. Conclusion Our study revealed the high frequency of biofilm forming XDR A. baumannii in ICU patients, with a high prevalence of biofilm related genes of csuE and pgaB. It seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of XDR A. baumannii in our country.

Molecular typing of multi-drug resistant Acinetobacter baumannii isolates from clinical and environmental specimens in three Iranian hospitals by pulsed field gel electrophoresis

“…Our results are consistent with previous reports which showed that more than 75% of A. baumannii isolates form biofilms [23,24]. Previous studies have reported a positive relationship between biofilm formation and antibiotic resistance in A. baumannii isolates [17,25,26]. In our study, all strong biofilm forming A. baumannii isolates were XDR.…”

“…baumannii formed biofilm, which is in agreement with previous studies [2,17,22]. According to our results, 44.9% of isolates showed strong ability to biofilm formation.…”

“…These results can probably be attributed to inappropriate strategies of disinfection and hand washing by health workers in hospitals. Furthermore, 41(95.3%) clinical isolates were resistant to all tested antibiotics and were XDR, which agrees with other investigations conducted in Iran [16,17]. Of the 8 antimicrobials tested, the most potent ones were colistin and tigecycline (100%) for all clinical and environmental isolates.…”

<p>Discovery of a Novel Hypervirulent <em>Acinetobacter baumannii</em> Strain in a Case of Community-Acquired Pneumonia</p>

“…5 In the case of this isolate, LS01, multiple virulence factors were identified including genes associated with biofilm formation, adherence, phospholipase, and iron uptake. Interestingly, many of these virulence genes have also been identified in MDR A. baumannii including ompA, bap, bfmS, csgA csuE, and pgaB 19 as well as the ATCC 17978-mff, AB5075-UW, and MDR-ZJ06 strains (data not shown). Despite the prevalence of these genes in MDR A. baumannii, one study found that there was no significant difference in the presence of ompA and bap genes between environmental and clinical isolates.…”

Identification and Elimination of the Clinically Relevant Multi-Resistant Environmental Bacteria Ralstonia insidiosa in Primary Cell Culture

“…With the percentage of infections with MDR Gram-negative bacteria increasing, treatment options are limited [ 17 ]. Strong biofilm producers like Acinetobacter baumannii [ 18 ] or Ralstonia species are hard to fight, as they are well-protected against antimicrobials. The bacterial genus Ralstonia includes ubiquitous environmental bacteria known as phytopathogens ( R. solanacearum ) [ 19 ] and are a growing threat in hospitals, e.g., for patients under mechanical ventilation or suffering from cystic fibrosis ( R. pickettii , R. insidiosa , and R. mannitolilytica ) [ 20 , 21 , 22 ].…”