Evaluation of Three Carbapenemase-Phenotypic Detection Methods and Emergence of Diverse VIM and GES Variants among Pseudomonas aeruginosa Isolates in Tunisia

Abstract

Background: Since 2012, few reports on the molecular epidemiology of Pseudomonas aeruginosa were reported in Tunisia. Objectives: This study aimed to evaluate carbapenem-resistance determinants and molecular epidemiology and to compare the carbapenemase-phenotypic detection methods of multidrug-resistant P. aeruginosa isolates. Methods: During a period of four years (2014 to 2017), all imipenem-ceftazidime-resistant P. aeruginosa isolates were retrospectively selected at the microbial laboratory of Charles Nicolle hospital of Tunis. These isolates were examined by the modified Hodge test, modified carbapenem inactivation method (mCIM), and another mCIM, called CIMTris, and their performance was evaluated using PCR analysis as the gold standard. Results: A total of 35 isolates were recovered among patients hospitalized in different units. All strains were colistin-susceptible.All carbapenem-resistant isolates showed a high-level resistance to carbapenems. CIMTris and mCIM showed 96.15% and 46.15% sensitivity and 44.44% and 100% specificity, respectively, for detecting carbapenemase production.Conclusions: CIMTris is a promising approach for detecting carbapenemase activity in P. aeruginosa and merits further testing. Moreover, this study described the first detection of GES-5- and GES-9-producing P. aeruginosa in Tunisia as well as the co-occurrence of the blaGES-5 and blaVIM-11 carbapenemase genes in one isolate. These findings are of great concern because the rapid dissemination of MDR strains represents a major therapeutic and epidemiological threat.

High Prevalence of GES-5 Variant and Co-Expression of VIM-2 and GES-45 among Clinical Pseudomonas aeruginosa Strains in Tunisia

“…Moreover, four isolates (7%) were VIM-2 MBL producers. This result aligns with the recent studies reporting the detection of GES-5 and VIM-2 in the CRPA of Tunisia [ 30 , 31 ], and it is worth mentioning that this GES-5 prevalence in CRPA might be a sign of the start of the expansion of these strains in Tunisia. On the other hand, the predominance of VIM-2 among P. aeruginosa was previously revealed in studies performed in Tunisia [ 25 , 28 , 29 , 31 ] and in other countries such as the United Arab Emirates [ 34 ], Spain [ 32 , 43 , 44 , 48 ], Russia, the United States [ 14 ], Lebanon, and Egypt [ 49 , 50 ].…”

“…Additionally, the successful worldwide spread of high-risk clones of P. aeruginosa poses a threat to global public health that needs to be studied and managed. However, few reports have been conducted on the molecular epidemiology or molecular typing of CRPA in Tunisia [ 29 , 30 , 31 ]. The aim of the present study was to analyze the characteristics of clinical CRPA isolates recovered from the Military Hospital of Tunis, including their antimicrobial resistance, integrons, virulence factors, and molecular typing.…”

Uncovering the Resistance Mechanisms in Extended-Drug-Resistant Pseudomonas aeruginosa Clinical Isolates: Insights from Gene Expression and Phenotypic Tests

“…Nevertheless, our study showed GES as the most encountered carbapenemase gene in P. aeruginosa . This was also found in other studies, conducted in Iran, Tunisia, Egypt and Japan [ 41 , 42 , 43 , 44 ]. A recent review on the frequency of carbapenemase genes showed the high prevalence of bla VIM and bla IMP in Romania [ 45 ].…”

Outbreak of an extensively resistant strain of <em>Pseudomonas aeruginosa</em> in the US

“…This is the first VIM-GES-CRPA outbreak reported in the US and globally; no other confirmed or suspected outbreaks have been documented. However, several genomic analysis studies have identified the co-expression of VIM and GES genes, of differing variants, in isolated cases in several countries [28][29][30][31][32][33] (Table 1). Although this previous outbreak was caused by a different P. aeruginosa strain, it demonstrates the bacteria's propensity to cause nosocomial infections.…”

“…Unfortunately, there is limited data regarding global VIM-GES-CRPA prevalence, and although isolated confirmed cases have occurred in several countries, there is likely underreporting [28][29][30][31][32][33]. Ezricare eyedrops were marketed in the US [41], however, the outbreak source could be certain eyedrop ingredients or manufacturing equipment.…”