Imipenem Resistant Pseudomonas aeruginosa: The fall of the final quarterback

Glyphosate and glyphosate-based herbicides (GBHs) induce phenotypic imipenem resistance in Pseudomonas aeruginosa

GBHs are the most widely used herbicides for weed control worldwide that potentially affect microorganisms, but the role of their sublethal exposure in the development of antibiotic resistance of Pseudomonas aeruginosa is still not fully investigated. Here, the effects of glyphosate acid (GLY), five glyphosate-based herbicides (GBHs), and POE(15), a formerly used co-formulant, on susceptibility to imipenem, a potent carbapenem-type antibiotic, in one clinical and four non-clinical environmental P. aeruginosa isolates were studied. Both pre-exposure in broth culture and co-exposure in solid media of the examined P. aeruginosa strains with 0.5% GBHs resulted in a decreased susceptibility to imipenem, while other carbapenems (doripenem and meropenem) retained their effectiveness. Additionally, the microdilution chequerboard method was used to examine additive/antagonistic/synergistic effects between GLY/POE(15)/GBHs and imipenem by determining the fractional inhibitory concentration (FIC) indexes. Based on the FIC index values, glyphosate acid and Total demonstrated a potent antagonistic effect in all P. aeruginosa strains. Dominator Extra 608 SL and Fozat 480 reduced the activity of imipenem in only one strain (ATCC10145), while POE(15) and three other GBHs did not have any effect on susceptibility to imipenem. Considering the simultaneous presence of GBHs and imipenem in various environmental niches, the detected interactions between these chemicals may affect microbial communities. The mechanisms of the glyphosate and GBH-induced imipenem resistance in P. aeruginosa are yet to be investigated.

Toxicity Study and Antibacterial Effects of the Leaves Extracts of Boscia coriacea and Uvaria leptocladon

Background

The objective of this study was to evaluate the in vivo toxicity and antibacterial activity of the leaves extracts of Boscia coriacea and Uvaria leptocladon.

Methods

Extraction was performed using 80% methanol by maceration and Soxhlet extraction method. Evaluation of the acute toxicity of the extracts was based on the Organization for Economic Cooperation and Development (OECD) guideline. Evaluation of antibacterial activity of the extracts was done by agar well diffusion assay. Determinations of minimum inhibitory concentrations (MIC) of the extracts were performed by broth macro-dilution method. The checkerboard method was used for the determination of combined effect of antibiotics and the extracts. Paired T-test and one way analysis of variance were used for statistical analysis.

Results

B. coriacea and U. leptocladon have no toxic effect in Swiss albino mice up to dose of 5000 mg/kg. B. coriacea and U. leptocladon showed antibacterial activity at concentration of 500 mg/ml. The chloroform-methanol fraction of B. coriacea and U. leptocladon showed the highest antibacterial activity at concentration of 25 mg/ml. The MIC and minimum bactericidal concentration (MBC) of B. coriacea were 125 mg/ml and 250 mg/ml, respectively. The MIC of U. leptocladon ranged from 31.25 mg/ml to 62.5 mg/ml, while its MBC ranged from 62.5 to 125 mg/ml. The combination assay of B. coriacea and the antibiotics showed additive effect, while U. leptocladon and the antibiotics showed indifferent effect.

Conclusion

The findings showed that U. leptocladon and B. coriacea leaves extracts have antibacterial activity and no toxicity in animal model.

Imipenem Resistance in Gram-Negative Bacteria in the Central Pediatric Teaching Hospital in Baghdad, Iraq

Antimicrobial resistance (AMR) is a serious challenge for infectious disease prevention and treatment, according to the World Health Organization. It is a worldwide problem caused primarily by inappropriate and insufficient therapy, misuse of antimicrobials without physician supervision, unnecessary hospital readmissions, and other factors. AMR has several consequences, including increased medical costs and mortality. The present study aimed to evaluate imipenem resistance in gram-negative bacteria in Central Pediatric Teaching Hospital in Baghdad, Iraq, and determine this bacteria resistance in different samples. Initially, a total of 100 different samples were collected from child patients from October 1, 2020, to August 31, 2021. Each isolate was identified using VITEK 2 automated microbiology system. The recorded data showed that the isolated organisms resistant to imipenem included Klebsiella pneumonia (n=21), Pseudomonas aeruginosa (n=19), and Acinetobacter baumannii (n=16). In the current study, Klebsiella pneumonia was the most common pathogen in males (n=57) compared to female (n=43), followed by Pseudomonas aeruginosa and Acinetobacter baumannii, particularly in the age range of 1 day- 3 years. Depending on the sample type, Klebsiella pneumonia, the most imipenem-resistant bacteria, was found more in the urine of patients with urinary tract infections. Pseudomonas aeruginosa was equally found in blood, urine, wound swab, and sputum samples. In comparison to other samples, Acinetobacter baumannii was found in greater numbers in the blood and in an equal number in urine and cerebrospinal.

Detection of synergistic antimicrobial resistance mechanisms in clinical isolates of Pseudomonas aeruginosa from post-operative wound infections

Infections caused by carbapenem-resistant Pseudomonas aeruginosa are life-threatening due to its synergistic resistance mechanisms resulting in the ineffectiveness of the used antimicrobials. This study aimed to characterize P. aeruginosa isolates for antimicrobial susceptibility, biofilm formation virulence genes, and molecular mechanisms responsible for resistance against various antimicrobials. Out of 700 samples, 91 isolates were confirmed as P. aeruginosa which were further classified into 19 non-multidrug-resistant (non-MDR), 7 multidrug-resistant (MDR), 19 extensively drug-resistant (XDR), and 8 pan drug-resistant (PDR) pulsotypes based on standard Kirby Bauer disc diffusion test and pulse field gel electrophoresis. In M9 minimal media, strong biofilms were formed by the XDR and PDR pulsotypes as compared to the non-MDR pulsotypes. The virulence genes, responsible for the worsening of wounds including LasB, plcH, toxA, and exoU, were detected among all MDR, XDR, and PDR pulsotypes. Carbapenemase activity was phenotypically detected in 45% pulsotypes and the responsible genes were found as bla_GES (100%), bla_VIM (58%), bla_IMP (4%), and bla_NDM (4%). Real-time polymerase chain reaction showed the concomitant use of multiple mechanisms such as oprD under-expression, enhanced efflux pump activity, and ampC overexpression in the resistant isolates. Polymyxin is found as the only class left with more than 80% susceptibility among the isolates which is an alarming situation suggesting appropriate measures to be taken including alternative therapies. KEY POINTS: • Multidrug-resistant P. aeruginosa isolates formed stronger biofilms in minimal media. • Only polymyxin antimicrobial was found effective against MDR P. aeruginosa isolates. • Under-expression of oprD and overexpression of ampC were found in resistant isolates.

Epidemiology and high incidence of metallo-β-lactamase and AmpC-β-lactamases in nosocomial Pseudomonas aeruginosa

OBJECTIVES

Isolates producing metallo-β-lactamase (MBL) have a significant impact on therapeutic and diagnostic layouts, plus their increased frequency has been reported globally. Determination of incidence of clinical isolates of Pseudomonas aeruginosa that are capable of producing MBL and AmpC-β-lactamases making them resistant to imipenem and cefoxitin.

MATERIALS AND METHODS

Out of 1159 collected samples of urine, wound swabs, blood, tissue, and pus, the isolation rate of P. aeruginosa in the period of March 2020 to February 2021 was 22.0% (255/1159). Bacterial strains that were resistant towards imipenem were further processed for detecting the β-lactamase group of genes followed by statistical analysis of risk factors done based on clinical sample, gender, plus department of sample collection.

RESULTS

The percentage of resistance against imipenem was found to be 53%. Out of 135 strains, phenotypic tests revealed MBLs incidence to be 61.5% by combination disc test and 81.5% by Modified Hodge test (MHT). Frequencies of blaIMP-1, blaVIM, blaSHV, blaTEM, and blaOXA genes were calculated to be 13%, 15%, 32%, 43%, and 21%, respectively. Co-expressions of blaMBLs (blaVIM and blaIMP-1) plus blaESBL (blaSHV, blaOXA, blaTEM) were detected using simplex and multiplex PCR. blaTEM, blaSHV, and blaOXA co-existed in 7.5% of clinical isolates. 5.5% of the isolates exhibited simultaneous expression of MBL/ESBL genes. 15% of the isolates resistant to cefoxitin were positive for the blaAmpC gene (17/114).

CONCLUSION

This is a pioneer report from Pakistan that concomitantly presents expression of blaVIM and blaIMP-1 with blaTEM, blaOXA, blaSHV, and blaAmpC in isolates of P. aeruginosa.

Polymyxin B resistance rates in carbapenem-resistant Pseudomonas aeruginosa isolates and a comparison between Etest® and broth microdilution methods of antimicrobial susceptibility testing

Polymyxin B has been considered to be the last line of defense for life-threatening infections caused by multiple drug resistant gram-negative pathogens, including carbapenem-resistant Pseudomonas aeruginosa (CRPA). The present study analyzed CRPA resistance to polymyxin B in the Suzhou district of China. Additionally, polymyxin B resistance rates were compared in different parts of the world to determine global trends. The present study also assessed the reliability and effectiveness of the Etest^® in a clinical setting, as laboratories lack a reliable and efficient susceptibility test for polymyxin B. The susceptibility rate of polymyxin B reached 96.0%, which is in accordance with results obtained from the United States of America, Europe, Africa and the majority of Asian countries. However, the rate of polymyxin B non-susceptibility (resistant or intermediate) in Singapore is 0.53 (95% confidence interval, 0.12-0.93). In addition, the susceptibility rate of polymyxin B determined via Etest^® was not significantly increased compared with that determined via broth microdilution (98.0 vs. 96.0%; P=0.558). Essential and categorical agreement rates reached 98.0%. In conclusion, the polymyxin B resistance rate of CRPA isolates is relatively low in the majority of countries, with the exception of Singapore. Furthermore, Etest^® may be a reliable clinical method for the measurement of polymyxin B resistance in CRPA isolates.

Frequency and antibiogram of multi-drug resistant pseudomonas aeruginosa in a Tertiary Care Hospital of Pakistan

Objective:

To determine pathogen burden and susceptibility pattern of multi-drug resistant (MDR) Pseudomonas aeruginosa isolates from clinical specimens in Karachi.

Methods:

It was In-vitro Clinical study, conducted in department of Pharmacology, Ziauddin University, and isolates were collected from various specimens such as pus, tracheal aspiration, wound swab, blood and urine in Microbiology department of Ziauddin Hospital, Nazimabad campus, Karachi. The antibiotic susceptibility pattern was determined by Kirby Bauer Disc diffusion method. Samples were processed as per procedures defined by Clinical and Laboratory Standards Institute (CLSI) guidelines 2018.

Results:

About 55% were found to be multi drug resistant P. aeruginosa. Majority of the isolates (35.4%) were recovered from the age range 60-80 years. Maximum number of MDR P. aeruginosa was isolated from pus (33.1%) followed by tracheal aspiration (20.6%). Highest sensitivity was seen by colistin (100%) followed by ceftolozane/tazobactam (60%). Least sensitivity was observed with imipenem (19%). However, increase trend of resistance was seen among all antipesudomonal drugs.

Conclusion:

Increasing frequency of infections due to MDR P. aeruginosa is an emerging threat in our set up which can be prevented by prescribing antibiotics judiciously. Consistent lab detection and surveillance regarding this resistant pathogen is compulsory for providing effective health care to community.

High Prevalence of Antimicrobial Resistance Among Gram-Negative Isolated Bacilli in Intensive Care Units at a Tertiary-Care Hospital in Yucatán Mexico

Background and Objectives: Antimicrobial resistance (AMR) is increasing worldwide and imposes significant life-threatening risks to several different populations, especially to those in intensive care units (ICU). The most commonly isolated organisms in ICU comprise gram-negative bacilli (GNB), and these represent a leading cause of serious infections. This study was conducted to describe the prevalence of resistance in GNB isolated from patients in adults, pediatric, and neonatal ICU in a tertiary-care hospital in Mérida, Mexico. Materials and Methods: A retrospective study was done on samples collected in Neonatal (NICU), Pediatric (PICU) and Adult (AICU) ICU of Unidad Médica de Alta Especialidad, Instituto Mexicano del Seguro Social in Mérida, México. The identification of isolates and antimicrobial susceptibility testing were performed using an automated system. Results: A total of 517 GNB strains were isolated. The most common positive culture was bronchial secretions. Pseudomonas aeruginosa was the prevalent pathogen in NICU and PICU, whereas Escherichia coli was common in the AICU. Overall, GNB exhibited a high resistance rates for Ampicillin (95.85%), Cefuroxime (84.17%), Piperacillin (82.93%), Cefotaxime (78.07%), Ceftriaxone (77.41%), Aztreonam (75.23%), Cefazolin (75.00%), and Ceftazidime (73.19%). There are significant differences in the resistance rates of GNB from different ICUs for penicillins, cephalosporins, carbapenems and fluoroquinolones drugs. Escherichia coli (multidrug-resistant [MDR] = 91.57%, highly resistant microorganisms [HRMO] = 90.36%) and Acinetobacter baumannii (MDR = 86.79%, HRMO = 83.02%) exhibited the highest percentage of MDR and HRMO profiles. The prevalence of the extended-spectrum beta-lactamases (ESBL)-producing isolates was 83.13% in E. coli, 78.84% in Klebsiella pneumoniae, and 66.67% in Proteus mirabilis, respectively. Conclusions: The high resistance rates to drugs were exhibited by our GNB isolates. Continuous surveillance and control of the use of antimicrobials are urgently needed to reduce the emergence and spreading of MDR, HRMO, and/or ESBL-producing bacilli.

High frequency and molecular epidemiology of metallo-β-lactamase-producing gram-negative bacilli in a tertiary care hospital in Lahore, Pakistan

Background

Metallo-β-lactamase (MBL)-producing isolates have a strong impact on diagnostic and therapeutic decisions. A high frequency of MBL-producing gram-negative bacilli has been reported worldwide. The current study was based on determining the incidence of MBL-producing imipenem-resistant clinical isolates and investigating the β-lactamase gene variants in strains conferring resistance to a carbapenem drug (imipenem).

Methods

A total of 924 gram negative isolates were recovered from a tertiary care hospital in Lahore, Pakistan, during a two-year period (July 2015 to February 2017). The initial selection of bacterial isolates was based on antibiotic susceptibility testing. Strains resistant to imipenem were processed for the molecular screening of β-lactamase genes. Statistical analysis for risk factor determination was based on age, gender, clinical specimen and type of infection.

Results

The rate of imipenem resistance was calculated to be 56.51%. Among the 142 strains processed, the phenotypic tests revealed that the incidence of MBLs was 63.38% and 86.61% based on the combination disc test and the modified Hodge test, respectively. The frequencies of bla_TEM, bla_SHV,bla_OXA,bla_IMP-1, and bla_VIM genes were calculated to be 46%, 34%, 24%, 12.5% and 7%, respectively. The co-expression of bla_MBL (bla_IMP and bla_VIM) and bla_ESBL (bla_TEM, bla_SHV,bla_OXA) was also detected through multiplex and singleplex PCR. bla_OXA, bla_TEM and bla_SHV coexisted in 82% of the isolates. Co-expression of ESBL and MBL genes was found in 7% of the isolates.

Conclusion

To our knowledge, this is the first report from Pakistan presenting the concomitant expression of bla_OXA, bla_TEM and bla_SHV with bla_IMP-1 and bla_VIM in MBL-producing gram-negative bacilli.

Systematic review and meta-analysis of imipenem-resistant Pseudomonas aeruginosa prevalence in Iran

INTRODUCTION

Imipenem-resistant Pseudomonas aeruginosa (IRPA), due to resistance to different classes of antibiotics and its remarkable capacity to survive in harsh and adverse conditions such as those in the hospital environment, is considered a serious threat to the healthcare system. Given the great impact of IRPA on patients' outcome and in order to possibly improve antibiotic prescription, this study was conducted to determine the prevalence of clinical isolates of IRPA in different parts of Iran.

METHODS

A systematic literature search was performed in PubMed, Web of Science, Google Scholar and Scopus, as well as in two Iranian domestic search engines, i.e., Iranian Scientific Information Database and Magiran. Finally, after applying exclusion and inclusion criteria 37 articles with full-texts describing the prevalence of imipenem-resistant P. aeruginosa were selected for meta-analysis and systematic review.

RESULTS

The pooled estimation of 5227 P. aeruginosa isolates in this analysis showed that the percentage of imipenem-resistant P. aeruginosa is about 54% in the Iranian population (95%CI: 0.47-0.62, logit event rate=0.19, 95%CI: -0.12,0.49).

CONCLUSION

The findings of this analysis show that in the majority of Iranian hospitals the relative frequency of IRPA is high, therefore, in order to prevent further dissemination of IRPA, more appropriate antibiotic prescription and infection control policies must be implemented by decision-makers.