Pseudomonas aeruginosa is an opportunistic pathogen which is associated with nosocomial infections and causes various diseases including urinary tract infection, pneumonia, soft-tissue infection and sepsis. The emergence of P. aeruginosa-acquired metallo-β-lactamase (MBL) is most worrisome and poses a serious threat during treatment and infection control. The objective of this study was to identify antibiotic susceptibility, phenotypic detection of MBL production and to determine the prevalence of MBL genes in carbapenem-resistant P. aeruginosa isolated from different clinical samples.
A total of 329 non-duplicate P. aeruginosa isolated from various clinical samples from two hospitals in China between September 2017 and March 2019 were included in this study. Phenotypic detection of MBL was performed by the combined detection method using imipenem and imipenem-ethylenediaminetetraacetic acid (EDTA) discs. MBL-encoding genes including bla VIM-1 , bla VIM-2 , bla IMP-1 , bla IMP-2 , bla SPM-1 , bla SIM , bla NDM-1 and bla GIM were detected by polymerase chain reaction (PCR).
Of the 329 P. aeruginosa, majority of the isolates were resistant to imipenem (77.5%) followed by meropenem (64.7%). Of the 270 P. aeruginosa isolates tested, 149 (55.2%) isolates were found to be positive for MBL detection. Of the different samples, 57.8% (n = 26) of P. aeruginosa isolated from blood were found to be positive for MBL production. Of the various MBL genes, bla IMP-1 (28.2%) was the most predominant gene detected followed by bla VIM-2 (18.8%), bla VIM-1 (16.1%), bla NDM-1 (9.4%), bla IMP-2 (6.7%), bla SIM (6.0%), bla SPM-1 (4.0%) and bla GIM (1.3%) genes.
The high resistance of P. aeruginosa toward imipenem and meropenem and the high prevalence of bla IMP-1 and bla VIM-2 set the alarm on the increasing, perhaps the increased, carbapenem resistance. In addition to routine antibiotic susceptibility testings, our results emphasize the importance of both the phenotypic and genotypic MBL detection methods in routine practice for early detection of carbapenem resistance and to prevent further dissemination of this resistant pathogen.
Ahmad-Nejad P. Ghebremedhin B. Edited by:
Pseudomonas aeruginosa, an opportunistic pathogen, is associated with nosocomial infections and causes various diseases including pneumonia, urinary tract infection, soft-tissue infection and sepsis . Infections caused by multidrug-resistant (MDR) P. aeruginosa are associated with significant morbidity and mortality. A high level of intrinsic and acquired resistance to multiple antibiotics exhibited by P. aeruginosa makes it challenging to treat and limits the treatment options . Pseudomonas aeruginosa exhibits almost all known resistance mechanisms; however, enzyme production is the major mechanism of acquired resistance, especially β-lactamase production . The increased prevalence of extended-spectrum β-lactamase (ESBL)-producing P. aeruginosa led to the use of carbapenems. Carbapenems are the last choice of drug for the treatment of P. aeruginosa infections. However, the alarming increase in carbapenem resistance is a cause of serious concern in the treatment of P. aeruginosa infections . The World Health Organization (WHO) has identified 12 most common bacteria that pose a challenge to human health. Among these, carbapenem-resistant P. aeruginosa was designated as one of the highly critical and poses a serious threat to patients who require ventilators and blood catheters . β-lactamases are classified into four different classes: classes A, C and D act through a serine-based mechanism and metallo-β-lactamase (MBL), while class B requires a bivalent metal ion for its activity . Of all these mechanisms, the emergence of P. aeruginosa-acquired MBL is the most worrisome and poses a serious threat during treatment and infection control . Except for monobactams, MBL-producing strains can hydrolyze all other β-lactam antibiotics including penicillin, cephamycins, cephalosporin and carbapenems . The MBL-producing P. aeruginosa strains carry co-resistance genes for other classes of antibiotics.
The MBL genes are present in mobile genetic elements such as plasmids, transposons, integrons or associated with insertion sequences with a tendency to spread within species and between different species . Several types of MBL genes were identified in P. aeruginosa: (i) Verona integron-encoded metallo-β-lactamase (VIM), (ii) imipenemase (IMP), Seoul imipenemase (SIM), (iii) Germany imipenemase (GIM), (iv) São Paulo metallo-β-lactamase (SPM), (v) New Delhi metallo-β-lactamase (NDM) types. Of these, VIM and IMP are the most prevalent types of acquired MBLs , . In 1991, MBL resistance was first reported in Japan; later it was reported in various countries including China, India, Taiwan, Singapore, Korea, Italy, France, Greece, Australia, Germany, Austria, Turkey, Bulgaria, Netherlands, Spain, Mexico, Colombia and USA . Mortality due to MBL-producing P. aeruginosa ranged from 70% to 90% , .
When patients with severe infections caused by MBL-producing P. aeruginosa are treated with antibiotics, it often leads to poor clinical outcome. Thus, it is highly essential to detect MBL-producing P. aeruginosa as early as possible for the effective treatment of critically ill patients within clinical settings. The present study aimed to identify antibiotic susceptibility, phenotypic detection of MBL and to determine the prevalence of MBL genes in carbapenem-resistant P. aeruginosa isolated from different clinical samples.
Materials and methods
A total of 329 non-duplicate P. aeruginosa isolated from various clinical samples from the Beijing Friendship Hospital, Capital Medical University, Beijing, China and The Second Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, China between September 2017 and March 2019 were included in this study. The isolates were identified as P. aeruginosa using the VITEK 2 system (bioMérieux, Craponne, France). Demographic data and other relevant details of patients from whom P. aeruginosa was isolated were collected from the hospital medical record department. The Institutional Ethical Board approved the study (IRB: 037-2017).
Antibiotic susceptibility test for all P. aeruginosa isolates was performed by disc diffusion method on Mueller-Hinton agar (MHA) plates. The following antibiotics were used during the test: imipenem (10 μg), meropenem (10 μg), gentamicin (10 μg), amikacin (30 μg), cefotaxime (30 μg), ceftazidime (30 μg), norfloxacin (10 μg), ciprofloxacin (5 μg), piperacillin+tazobactam (100/10 μg), colistin (10 μg) and tigecycline (15 μg) (Himedia, Mumbai, India). The results were interpreted as per the Clinical Laboratory Standard Institute (CLSI) guidelines .
Phenotypic detection of MBL production
All isolates that were resistant and intermediately resistant to imipenem by disc diffusion method were subjected to MBL production test by the combined disk method . Briefly, overnight culture adjusted to 0.5 MacFarland standard was inoculated on to MHA plates. Two disks of 10 μg imipenem (10 μg) and imipenem (10 μg) with 0.5 M ethylenediaminetetraacetic acid (EDTA) were placed 25 mm apart on the MHA plates. The plates were incubated at 37 °C for 16–18 h and observed for the zone of inhibition. A zone of ≥7 mm in the imipenem plus EDTA disc compared to imipenem alone disc was considered as positive for the presence of carbapenem resistance (MBL resistance).
Detection of MBL genes
Carbapenem-resistant isolates were subjected to polymerase chain reaction (PCR) for the detection of MBL genes including bla VIM-1 , bla VIM-2 , bla IMP-1 , bla IMP-2 , bla SPM-1 , bla SIM , bla NDM-1 and bla GIM as described by Azimi et al. . In-house P. aeruginosa isolates positive for all tested genes and confirmed earlier through sequencing were used as controls for PCR. The gene-specific primer sequence and their annealing temperature are presented in Table 1 , , . DNA was extracted using a commercial genomic DNA extraction kit (Thermo Fisher Scientific, Waltham, MA, USA). The PCR reaction mixture contained 12.5 μL of ReadyMix™ Taq PCR Reaction Mix (Sigma-Aldrich, St. Louis, MO, USA), 2.5 μL of the DNA (20 pg), and 0.5 μM of each primer and nuclease-free water made up to 25 μL. The PCR cycling conditions were as follows: initial denaturation at 96 °C for 10 min, followed by 30 cycles of 96 °C for 1 min, the specific annealing temperatures of the respective primers as presented in Table 1 for 1 min, and 72 °C for 1 min, and a final extension step at 72 °C for 10 min. After PCR, the amplicons were resolved in 1.2% (w/v) agarose gel electrophoresis and visualized under a ultraviolet (UV) transilluminator (BioRad, Hercules, CA, USA).
|Gene||Primer sequence (5′-3′)||Annealing temperature, °C|
|bla VIM-1||F: 5′-AGTGGTGAGTATCCGACAG-3′
|bla VIM-2||F: 5′-ATGTTCAAACTTTTGAGTAAG-3′
|bla IMP-1||F: 5′-ACCGCAGCAGAGTCTTTGCC-3′
|bla IMP-2||F: 5′-GTTTTATGTGTATGCTTCC-3′
|bla SPM-1||F: 5′-GCGTTTTGTTTGTTGCTC-3′
|bla SIM||F: 5′-TACAAGGGATTCGGCATCC-3′
|bla NDM-1||F: 5′-GGCGGAATGGCTCATCACGA-3′
|bla GIM||F: 5′-TCGACACACCTTGGTCTG-3′
Descriptive statistics were performed to determine the frequencies. The chi-square (χ2) test, Student’s t-test and Pearson’s correlation coefficient tests were performed to analyze the data using SPSS statistical software (IBM SPSS Inc., Chicago, IL, USA, Ver. 2015). A p-value of <0.05 was considered statistically significant.
A total of 329 P. aeruginosa were isolated from 329 non-repetitive clinical samples collected from 307 patients (mean age, 49.7±6.7 years); of these, 171 (55.7%) were male and 136 (44.3%) were female. Various clinical samples included sputum (n=92, 28.0%), burnt wounds (n=71, 21.6%), bronchoalveolar lavage (BAL) (n=63, 19.1%), blood (n=45, 13.7%), pus (n=33, 10.0%) and others (n=25, 7.6%). Of the 307 patients, 171 (55.7%) patients were admitted in the intensive care unit (ICU) for various critical disease conditions (Table 2). Of the 307 patients, in 10 patients, two different samples were collected and in six patients, three different samples were collected.
|Description||No. of patients/samples, %|
|Age (mean±SD)||49.7 ± 6.7 years|
|In ICU||171 (55.7%)|
|In ward||136 (44.3%)|
|Under ventilator support||89 (28.3%)|
|On catheter||56 (18.2%)|
|Prior antibiotic therapy||237 (77.2%)|
|Respiratory disorder||127 (41.4%)|
|Burnt wound||80 (26.1%)|
|Urinary tract infection||9 (2.9%)|
|Clinical samples (n=329)|
|Burnt wound||71 (21.6%)|
|Bronchoalveolar lavage||63 (19.1%)|
ICU, intensive care unit; SD, standard deviation.
Of the 329 P. aeruginosa, majority of the isolates were resistant to imipenem (255, 77.5%) followed by meropenem (213, 64.7%), amikacin (209, 63.5%), gentamicin (201, 61.1%), norfloxacin (187, 56.8%), piperacillin/tazobactam (185, 56.2%), cefotaxime (184, 55.9%), ciprofloxacin (175, 53.2%), tigecycline (172, 52.3%), ceftazidime (167, 50.8%) and colistin (53, 16.1%). Compared to other samples, a higher number of P. aeruginosa (71, 77.2%) isolated from sputum samples were found to be resistant to imipenem (p>0.05). All isolates that were resistant to meropenem were found to be resistant to imipenem. The correlation coefficient showed that there was a significant association between the P. aeruginosa isolated from patients with respiratory diseases and imipenem resistance (r=0.98, p=0.029). Thirty-two (9.7%) isolates were found to be susceptible to all the antibiotics tested. A total of 207 (62.9%) isolates were found to be MDR strains as they were intermediately or fully resistant to at least three different classes of antibiotics. None of the P. aeruginosa isolated from blood samples was resistant to colistin (Table 3).
|Imipenem||59 (17.9%)||15 (4.6%)||255 (77.5%)|
|Meropenem||84 (25.5%)||32 (9.7%)||213 (64.7%)|
|Amikacin||72 (21.9%)||48 (14.6%)||209 (63.5%)|
|Gentamicin||94 (28.6%)||34 (10.3%)||201 (61.1%)|
|Norfloxacin||121 (36.8%)||21 (6.4%)||187 (56.8%)|
|Piperacillin/tazobactum||117 (35.6%)||27 (8.2%)||185 (56.2%)|
|Cefotaxime||91 (27.1%)||54 (16.4%)||184 (55.9%)|
|Ciprofloxacin||122 (37.1%)||32 (9.7%)||175 (53.2%)|
|Tigecycline||119 (36.2%)||38 (11.6%)||172 (52.3%)|
|Ceftazidime||114 (34.7%)||48 (14.6%)||167 (50.8%)|
|Colistin||227 (69.0%)||53 (14.9%)||53 (16.1%)|
Phenotypic detection of MBL production
All the isolates that were resistant (255, 77.5%) and intermediately resistant (15, 4.6%) to imipenem were subjected to MBL detection by the combined disk method. Of the 270 P. aeruginosa isolates tested, 149 (55.2%) isolates were found to be positive for MBL detection. Of the different samples, 57.8% (26/45) of P. aeruginosa isolated from blood were found to be positive for MBL, followed by P. aeruginosa isolated from pus (18/33, 54.5%), sputum (41/92, 44.6%), burnt wound (31/71, 43.7%), BAL (24/63, 38.1%) and urine (9/25, 36.0%). The MBL was predominantly detected in P. aeruginosa isolated from male (83, 55.7%) compared to female (66, 44.3%) patients (Table 4). The presence of MBL among P. aeruginosa isolated from different samples did not differ significantly (p>0.05).
|Antibiotics||Sputum (n=92)||Burnt wound (n=71)||BAL (n=63)||Blood (n=45)||Pus (n=33)||Urine (n=25)|
|Imipenem||86 (93.5%)||57 (80.3%)||45 (71.4%)||29 (64.4%)||21 (63.6%)||17 (68.0%)|
|Meropenem||75 (81.5)||65 (91.5%)||33 (52.4%)||20 (44.4%)||12 (36.4%)||8 (32.0%)|
|Amikacin||41 (44.6%)||52 (73.2%)||51 (80.9%)||22 (48.9%)||24 (72.7%)||19 (76.0%)|
|Gentamicin||42 (45.7%)||51 (71.8%)||47 (74.6%)||21 (46.7%)||26 (78.8%)||14 (56.0%)|
|Norfloxacin||56 (60.9%)||41 (57.7%)||26 (41.3%)||28 (62.2%)||21 (63.6%)||15 (60.0%)|
|Piperacillin/tazobactum||48 (52.2%)||61 (85.9%)||24 (38.1%)||21 (46.7%)||17 (51.5%)||14 (56.0%)|
|Cefotaxime||54 (58.7%)||40 (56.3%)||32 (50.8%)||23 (51.1%)||23 (69.7%)||12 (48.0%)|
|Ciprofloxacin||42 (45.7%)||53 (74.6%)||38 (60.3%)||19 (42.2%)||14 (42.4%)||9 (36.0%)|
|Tigecycline||36 (39.1%)||41 (57.7%)||44 (69.8%)||18 (40.0%)||17 (51.5%)||16 (64.0%)|
|Ceftazidime||71 (77.2%)||36 (50.7%)||21 (33.3%)||22 (48.9%)||9 (27.3%)||8 (32.0%)|
|Colistin||18 (19.6%)||15 (21.1%)||6 (9.5%)||0 (0.0%)||9 (27.3%)||5 (20.0%)|
BAL, bronchoalveolar lavage; MBL, metallo-β-lactamase.
Detection of MBL genes
All the 149 P. aeruginosa that were positive for carbapenem resistance were subjected to MBL gene detection by PCR. Of the various MBL genes tested, bla IMP-1 (41, 28.2%) was the most common gene detected from the isolates followed by the bla VIM-2 (28, 18.8%), bla VIM-1 (24, 16.1%), bla NDM-1 (14, 9.4%), bla IMP-2 (10, 6.7%), bla SIM (9, 6.0%), bla SPM-1 (6, 4.0%) and bla GIM (2, 1.3%) genes. The presence of the bla IMP-1 gene was significantly higher among the isolates tested (p=0.023). Of the various combinations identified, the presence of the bla IMP-1 gene along with bla IMP-2 was the most common combination of genes present among the isolates (Table 5). Fourteen (9.4%) isolates did not amplify any of the genes tested.
|Gene combination||No. of isolates|
|bla IMP-1||41 (27.5%)|
|bla VIM-2||28 (18.8%)|
|bla VIM-1||24 (16.1%)|
|bla NDM-1||14 (9.4%)|
|bla IMP-2||10 (6.7%)|
|bla SIM||9 (6%)|
|bla SPM-1||6 (4%)|
|bla GIM||2 (1.3%)|
|bla IMP-1 , bla IMP-2||6 (4.0%)|
|bla VIM-1 , bla VIM-2||4 (2.7%)|
|bla IMP-1 , bla NDM-1||4 (2.7%)|
|bla SIM , bla IMP-2||2 (1.3%)|
|bla NDM-1 , bla VIM-1 , bla IMP-1||2 (1.3%)|
|bla NDM-1 , bla GIM , bla IMP-1||2 (1.3%)|
|bla NDM-1 , bla VIM-1 , bla IMP-1 , bla IMP-2||1 (0.7%)|
Pseudomonas aeruginosa infections are effectively treated by carbapenems; however, resistance toward these antibiotics spread across hospitals due to the extensive use of antibiotics . Intrinsic resistance among P. aeruginosa leads to MDR and is associated with high mortality. This study reported a high level of carbapenem resistance among P. aeruginosa isolated from various clinical samples. Although not significant, P. aeruginosa (77.2%) isolated from sputum samples were found to be resistant to imipenem (p>0.05). The majority of our isolates were from sputum samples (28.0%) and the majority of our sputum samples (72.4%) were from patients with respiratory diseases. A significant association between the P. aeruginosa isolated from patients with respiratory diseases and imipenem resistance (r=0.98, p=0.029) was found in this study. In our hospital, imipenem is one of the most commonly used antibiotics as first-line therapy for most of the cases with pseudomonas infection, especially for respiratory diseases and patients who are on ventilator support. An overexposure of this drug could possibly be the reason for this higher rate of imipenem resistance among our isolates.
A wide range of resistant mechanisms make P. aeruginosa swiftly change to the selective environmental pressure and makes it resistant to several classes of antibiotics. In this study, 77.5% of the isolates were found to be resistant to imipenem, which corroborates to that reported from Egypt (78.3%)  and China (73.3%) . Compared to other studies from the Asia-Pacific region including Iran (25.2%) , China (17.1%, 43.3%) , , Japan (28.5%)  and Taiwan (16%) , this study reported a much higher resistance toward imipenem. Another study from Iran reported a resistance of 98.8% . In a review article, Hong et al. presented an overview of the epidemiology and molecular characteristics of MBL-producing P. aeruginosa. The study which analyzed several publications from Asia, Europe, America and Africa reported imipenem resistance among P. aeruginosa ranging from 8% to 66% . In this study, meropenem resistance was the second most common resistance reported (64.7%) among our isolates. In addition to imipenem resistance, Hong et al. reported meropenem resistance ranging from 8% to 57% . In the aforementioned study, which covers multiple countries of all regions, the reported imipenem and meropenem resistance ranges among P. aeruginosa do not exceed the rate reported in this study . This implies that imipenem and meropenem resistance among our isolates was higher than that reported worldwide and needs special attention. In addition to the overuse of imipenem and meropenem in our hospital settings, the presence of resistant genes on mobile genetic elements may have also contributed to the spread of resistance within our isolates . In our study, 62.9% of the isolates were found to be MDR strains, which was higher than that reported from Brazil (37%) and Asia (42.8%) , .
In this study, 55.2% of the isolates were found to be MBL producers. A study from Iran, which included P. aeruginosa isolated from burnt wound, reported a lower rate (43.7%) of MBL producers compared to this study . Similarly, another study from Iran also reported a lower rate (37.7%) of MBL producers among their clinical isolates of P. aeruginosa . Hong et al. in a review article analyzed reports with varied carbapenem resistance rates. Compared to this study, the review article reported lower carbapenem-resistant isolates from South and Southeast Asia including Philippines (31.1%), Singapore (23.3%), Thailand (28.7%), Vietnam (46.7%) and India (32%); Oceanic including Australia (16%) and New Zealand (10.3%); East Africa including Kenya (13.7%); and North America including Canada (3.3%) and the United States (20%). A much higher rate was reported from Russia (75.3%) and Costa Rica (63.1%) . A meta-analysis from Iran, which included 14 publications on P. aeruginosa isolated from burn patients, reported a pooled prevalence rate of 76.8% carbapenem-resistant P. aeruginosa, which is much higher than that reported in this study . However, a study from China, which included P. aeruginosa isolated from cystic fibrosis patients, reported that 56.25% of their isolates were found to be MBL producers, which is comparable to that reported in this study . Although not significant, a relatively high number (41, 27.52%) of P. aeruginosa isolated from sputum samples were found to be MBL producers. However, in terms of percentage, P. aeruginosa isolated from blood samples yielded a higher rate (57.8%) of MBL producers. Pseudomonas aeruginosa isolated from male (55.7%) patients were found to be the predominant MBL producers.
Most of the MBL genes are located in the integrons within mobile genetic elements and are responsible for the dissemination of antibiotic resistance through horizontal gene transfer. In the past decade, the emergence and dissemination of the newly identified blaNDM and blaAIM and the most prevalent bla IMP , bla VIM , bla SIM and bla GIM MBL genes have been widely reported around the world . In this study, bla IMP-1 (28.2%) was the most common gene detected; bla VIM-2 (18.8%) was the second most common gene detected, followed by bla VIM-1 (16.1%). Similar to this study, a study from Iran which included MBL-producing P. aeruginosa reported that bla IMP (24.65%) was the predominant gene detected followed by blaVIM (11.5%) . Similarly, a study from Japan which included 180 P. aeruginosa reported that bla IMP-1 was the predominant gene detected (116/180 isolates) followed by bla VIM-2 (63/180 isolates) . While a meta-analysis from Iran which included P. aeruginosa from burn patients reported that the pooled prevalence of blaVIM was 21.4% and of bla IMP was 13.1%, the reported rates were higher than in this study . A study from Iran also reported that blaVIM (17.5%) was the most common gene followed by bla IMP (15.6%) . A study from China that included 63 MBL-producing P. aeruginosa reported that blaVIM was the most common gene but with a higher rate (84.1%) and bla IMP was the second most common gene (76.1%), however, with higher rates than those reported in this study . A study from Iran that included 19 MBL-producing P. aeruginosa reported that 31.5% of their isolates carried the blaVIM gene and 10.5% carried bla IMP , which was higher than that reported in this study . In contrast to our study, a study from Egypt reported that none of their P. aeruginosa was positive for the blaVIM gene . In the present study, 9.4% of our isolates were positive for the bla NDM-1 gene, which is lower than that reported from India (27%) . A study from Bahrain reported a lower rate of bla NDM-1 (2.5%) than that reported in this study . In the present study, the bla IMP-1 gene was significantly higher among the isolates tested (p=0.023). The bla IMP-1 gene along with bla IMP-2 was the most common combination found in this study. There was no significant difference in the presence of MBL genes with that of hospital settings, including ICU/in-ward patients, patients under ventilator and burnt wound patients (p>0.05). Fourteen (9.4%) isolates did not amplify any of the genes tested, and these isolates could possibly carry other resistant gene variations that were not tested in this study. A study to test more resistant gene variations could possibly reveal the resistant genes associated with these isolates. The present study suggests that with the predominance of the bla IMP-1 gene, blaVIM is also increasing in our region. In addition, the high rate of the bla NDM-1 gene signifies its spread and emphasizes the need for continuous monitoring for better patient management and infection control.
In conclusion, the relatively high resistance of P. aeruginosa toward imipenem and meropenem and the high prevalence of bla IMP-1 and bla VIM-2 set an alarm on the increasing, perhaps the increased, carbapenem resistance. In addition to routine antibiotic susceptibility testings, our results emphasize the importance of both the phenotypic and genotypic MBL detection methods in routine practice for early detection of carbapenem resistance and to prevent further dissemination of this resistant pathogen.
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Competing interests: Authors state no conflict of interest.
Informed consent: Informed consent was obtained from all individuals included in this study.
Ethical approval: Research involving human subjects complied with all relevant national regulations, institutional policies and is in accordance with the tenets of the Helsinki Declaration (as revised in 2013), and has been approved by the authors’ institutional human Ethics Committee (037-2017).
1. Rosenthal VD, Bijie H, Maki DG, Mehta Y, Apisarnthanarak A, Medeiros EA, et al. International Nosocomial Infection Control Consortium (INICC) report, data summary of 36 countries, for 2004–2009. Am J Infect Control 2012;40:396–407.10.1016/j.ajic.2011.05.020Search in Google Scholar
2. Mohanty S, Maurya V, Gaind R, Deb M. Phenotypic characterization and colistin susceptibilities of carbapenem-resistant of Pseudomonas aeruginosa and Acinetobacter spp. J Infect Dev Ctries 2013;7:880–7.10.3855/jidc.2924Search in Google Scholar
5. WHO publishes list of bacteria for which new antibiotics are urgently needed [https://www.who.int/en/news-room/detail/27-02-2017-who-publishes-list-of-bacteria-for-which-new-antibiotics-are-urgently-needed].Search in Google Scholar
7. Meletis G, Bagkeri M. Pseudomonas aeruginosa: multi- drug-resistance development and treatment options. In: Basak C, editor. Infection Control. Rijeka, Croatia: IntechOpen, 2013: 33–56.10.5772/55616Search in Google Scholar
9. Hong DJ, Bae IK, Jang IH, Jeong SH, Kang HK, Lee K. Epidemiology and characteristics of metallo-beta-lactamase-producing Pseudomonas aeruginosa. Infect Chemother 2015;47:81–97.10.3947/ic.2015.47.2.81Search in Google Scholar
10. Ramakrishnan K, Rajagopalan S, Nair S, Kenchappa P, Chandrakesan SD. Molecular characterization of metallo beta-lactamase producing multidrug resistant Pseudomonas aeruginosa from various clinical samples. Indian J Pathol Microbiol 2014;57:579–82.10.4103/0377-4929.142670Search in Google Scholar
12. Zavascki AP, Barth AL, Goncalves AL, Moro AL, Fernandes JF, Martins AF, et al. The influence of metallo-beta-lactamase production on mortality in nosocomial Pseudomonas aeruginosa infections. J Nat Sci Biol Med 2006;58:387–92.10.1093/jac/dkl239Search in Google Scholar
13. CLSI. M100-S25 performance standards for antimicrobial. Clinical and laboratory standards institute 950 west valley road, suite 2500 Wayne, PA 19087, USA, 2015.Search in Google Scholar
14. Behera B, Mathur P, Das A, Kapil A, Sharma V. An evaluation of four different phenotypic techniques for detection of metallo-beta-lactamase producing Pseudomonas aeruginosa. Indian J Med Microbiol 2008;26:233–7.10.1016/S0255-0857(21)01868-5Search in Google Scholar
15. Azimi A, Peymani A, Pour PK. Phenotypic and molecular detection of metallo-beta-lactamase-producing Pseudomonas aeruginosa isolates from patients with burns in Tehran, Iran. Rev Soc Bras Med Trop 2018;51:610–5.10.1590/0037-8682-0174-2017Search in Google Scholar PubMed
16. Shibata N, Doi Y, Yamane K, Yagi T, Kurokawa H, Shibayama K, et al. PCR typing of genetic determinants for metallo-beta-lactamases and integrases carried by gram-negative bacteria isolated in Japan, with focus on the class 3 integron. J Clin Microbiol 2003;41:5407–13.10.1128/JCM.41.12.5407-5413.2003Search in Google Scholar PubMed PubMed Central
17. Jovcic B, Lepsanovic Z, Suljagic V, Rackov G, Begovic J, Topisirovic L, et al. Emergence of NDM-1 metallo-beta-lactamase in Pseudomonas aeruginosa clinical isolates from Serbia. Antimicrob Agents Chemother 2011;55:3929–31.10.1128/AAC.00226-11Search in Google Scholar PubMed PubMed Central
19. Michalopoulos A, Falagas ME, Karatza DC, Alexandropoulou P, Papadakis E, Gregorakos L, et al. Epidemiologic, clinical characteristics, and risk factors for adverse outcome in multiresistant gram-negative primary bacteremia of critically ill patients. Am J Infect Control 2011;39:396–400.10.1016/j.ajic.2010.06.017Search in Google Scholar PubMed
20. Abaza AF, El Shazly SA, Selim HS, Aly GS. Metallo-beta-lactamase producing Pseudomonas aeruginosa in a Healthcare Setting in Alexandria, Egypt. Pol J Microbiol 2017;66:297–308.10.5604/01.3001.0010.4855Search in Google Scholar PubMed
21. Li Y, Zhang X, Wang C, Hu Y, Niu X, Pei D, et al. Characterization by phenotypic and genotypic methods of metallo-beta-lactamase-producing Pseudomonas aeruginosa isolated from patients with cystic fibrosis. Mol Med Rep 2015;11:494–8.10.3892/mmr.2014.2685Search in Google Scholar PubMed
22. Kazeminezhad B, Bostanmanesh Rad A, Gharib A, Zahedifard S. blaVIM and blaIMP genes detection in isolates of carbapenem resistant P. aeruginosa of hospitalized patients in two hospitals in Iran. Iran J Pathol 2017;12:392–6.10.30699/ijp.2017.28323Search in Google Scholar
23. Hu F, Guo Y, Yang Y, Zheng Y, Wu S, Jiang X, et al. Resistance reported from China antimicrobial surveillance network (CHINET) in 2018. Eur J Clin Microbiol Infect Dis 2019;38:2275–81.10.1007/s10096-019-03673-1Search in Google Scholar PubMed
24. Xu J, Duan X, Wu H, Zhou Q. Surveillance and correlation of antimicrobial usage and resistance of Pseudomonas aeruginosa. a hospital population-based study. PLoS One 2013;8:e78604.10.1371/journal.pone.0078604Search in Google Scholar PubMed PubMed Central
25. Kakeya H, Yamada K, Nakaie K, Takizawa E, Okada Y, Fujita A, et al. [A comparison of susceptibility of Pseudomonas aeruginosa clinical isolates to carbapenem antibiotics in our hospital]. Jpn J Antibiot 2014;67:241–8.Search in Google Scholar
26. Lee HS, Loh YX, Lee JJ, Liu CS, Chu C. Antimicrobial consumption and resistance in five Gram-negative bacterial species in a hospital from 2003 to 2011. J Microbiol Immunol Infect 2015;48:647–54.10.1016/j.jmii.2014.04.009Search in Google Scholar PubMed
27. Chung DR, Song JH, Kim SH, Thamlikitkul V, Huang SG, Wang H, et al. High prevalence of multidrug-resistant nonfermenters in hospital-acquired pneumonia in Asia. Am J Respir Crit Care Med 2011;184:1409–17.10.1164/rccm.201102-0349OCSearch in Google Scholar PubMed
28. Matos EC, Matos HJ, Conceicao ML, Rodrigues YC, Carneiro IC, Lima KV. Clinical and microbiological features of infections caused by Pseudomonas aeruginosa in patients hospitalized in intensive care units. Rev Soc Bras Med Trop 2016;49:305–11.10.1590/0037-8682-0446-2015Search in Google Scholar PubMed
29. Ghasemian A, Salimian Rizi K, Rajabi Vardanjani H, Nojoomi F. Prevalence of clinically isolated metallo-beta-lactamase-producing Pseudomonas aeruginosa, coding genes, and possible risk factors in Iran. Iran J Pathol 2018;13:1–9.10.30699/ijp.13.1.1Search in Google Scholar
30. Jabalameli F, Taki E, Emaneini M, Beigverdi R. Prevalence of metallo-beta-lactamase-encoding genes among carbapenem-resistant Pseudomonas aeruginosa strains isolated from burn patients in Iran. Rev Soc Bras Med Trop 2018;51:270–6.10.1590/0037-8682-0044-2018Search in Google Scholar PubMed
31. Mohanam L, Menon T. Coexistence of metallo-beta-lactamase-encoding genes in Pseudomonas aeruginosa. Indian J Med Res 2017;146(Supplement):S46–52.10.4103/ijmr.IJMR_29_16Search in Google Scholar PubMed PubMed Central
32. Joji RM, Al-Rashed N, Saeed NK, Bindayna KM. Detection of VIM and NDM-1 metallo-beta-lactamase genes in carbapenem-resistant Pseudomonas aeruginosa clinical strains in Bahrain. J Lab Physicians 2019;11:138–43.10.4103/JLP.JLP_118_18Search in Google Scholar PubMed PubMed Central
©2020 Wei Wang et al.,Lihua Ye et al., published by De Gruyter, Berlin/Boston
This work is licensed under the Creative Commons Attribution 4.0 International License.