Carbapenem-resistant Acinetobacter ventilator-associated pneumonia: Clinical characteristics and outcome

A Nonlinear Time-Series Analysis to Identify the Thresholds in Relationships Between Antimicrobial Consumption and Resistance in a Chinese Tertiary Hospital

Introduction

Balancing the benefits and risks of antimicrobials in health care requires an understanding of their effects on antimicrobial resistance at the population scale. Therefore, we aimed to investigate the association between the population antibiotics use and resistance rates and further identify their critical thresholds.

Methods

Data for monthly consumption of six antibiotics (daily defined doses [DDDs]/1000 inpatient-days) and the number of cases caused by five common drug-resistant bacteria (occupied bed days [OBDs]/10,000 inpatient-days) from inpatients during 2009–2020 were retrieved from the electronic prescription system at Nanjing Drum Tower Hospital, a tertiary hospital in Jiangsu Province, China. Then, a nonlinear time series analysis method, named generalized additive models (GAM), was applied to analyze the pairwise relationships and thresholds of these antibiotic consumption and resistance.

Results

The incidence densities of carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Klebsiella pneumoniae (CRKP), and aminoglycoside-resistant Pseudomonas aeruginosa were all strongly synchronized with recent hospital use of carbapenems and glycopeptides. Besides, the prevalence of carbapenem-resistant Escherichia coli was also highly connected the consumption of carbapenems and fluoroquinolones. To lessen resistance, we determined a threshold for carbapenem and glycopeptide usage, where the maximum consumption should not exceed 31.042 and 25.152 DDDs per 1000 OBDs, respectively; however, the thresholds of fluoroquinolones, third-generation cephalosporin, aminoglycosides, and β-lactams have not been identified.

Conclusions

The inappropriate usage of carbapenems and glycopeptides was proved to drive the incidence of common drug-resistant bacteria in hospitals. Nonlinear time series analysis provided an efficient and simple way to determine the thresholds of these antibiotics, which could provide population-specific quantitative targets for antibiotic stewardship.

Temporal association between antibiotic use and resistance in Gram-negative bacteria

The β-lactam/lactamase inhibitors (BLBLIs) combination drugs are considered an effective alternative to carbapenems. However, there is a growing concern that the increased use of BLBLIs may lead to increased resistance. This study determined the temporal association between the consumption of BLBLI and the antimicrobial resistance in Gram-negative bacteria. In this retrospective study, electronic data on the Gram-negative bacterial isolates, including A. baumannii, P. aeruginosa, E. coli, and K. pneumoniae from in-patients and susceptibility testing results were retrieved from the medical records of the clinical laboratory. A linear regression and cross-correlation analysis were performed on the acquired data. Increasing trends (p<0.05) in the consumption of BIBLI and carbapenem with a median use of 27.68 and 34.46 DDD/1000 PD per quarter were observed, respectively. A decreased trend (p=0.023) in the consumption of fluoroquinolones with a median use of 29.13 DDD/1000 PD per quarter was observed. The resistance rate of K. pneumoniae was synchronized with the BIBLI and carbapenem consumptions with a correlation coefficient of 0.893 (p=0.012) and 0.951 (p=0.016), respectively. The cross-correlation analysis against the consumption of BIBLI and meropenem resistant K. pneumoniae was peaked at 0-quarter lag (r=951, p=0.016). There was an increasing trend in the consumption of BLBLI and carbapenems. The increasing trend in the rates of resistance to piperacillin/tazobactam, in line with the increasing consumption of BLBLI, suggests that BLBLI has to be used with caution and cannot be directly considered as a long-term alternative to carbapenems.

Temporal association between carbapenems usage and antimicrobial resistance in gram-negative bacteria at a tertiary hospital in Nanjing, China

In this study, we investigated the temporal association between carbapenems usage and antimicrobial resistance among major Gram-negative bacteria, using the data of quarterly carbapenems consumptions and percentages of antibiotic resistance for Gram-negative bacteria from inpatients from 2013 to 2017 in a tertiary hospital from Jiangsu Province, China. First, carbapenems consumption showed an increasing trend in the past 5 years, accompanied with the rising rates of A. baumannii and P. aeruginosa resistance against imipenem. In A. baumannii, we identified correlations between carbapenems consumption and antimicrobial resistance against piperacillin/tazobactam, ceftazidime, ciprofloxacin and imipenem, respectively. Additionally, close correlations were observed between carbapenems consumption and antimicrobial resistance against ceftazidime and ciprofloxacin in E. coli. Our data indicated that a significant positive correlation between the usage of carbapenems and the rate of antimicrobial resistance among A. baumannii and E. coli, respectively. Carbapenems should be cautiously prescribed to prevent antimicrobial resistance outbreak in A. baumannii and E. coli.

New Delhi metallo-β-lactamase-producing Acinetobacter isolates among late-onset VAP patients: multidrug-resistant pathogen and poor outcome

Background

Acinetobacter spp. are increasingly important microbes involved in late-onset ventilator-associated pneumonia (VAP).

Purpose

The aims of this study were to determine the prevalence of New Delhi metallo-β-lactamase (MβL) (blaNDM-1)-producing Acinetobacter spp. among late-onset VAP patients in different intensive care units (ICUs) of Menoufia and Kasr Al Ainy University Hospitals, to investigate the possible risk factors contributing to the acquisition of blaNDM-1-producing Acinetobacter infection, and to correlate between antimicrobial resistance pattern and therapeutic efficacy as well as clinical outcomes of these patients.

Materials and methods

Sixty-four Acinetobacter isolates were collected from mechanically ventilated patients with suspected late-onset VAP and subjected to antimicrobial susceptibility testing. The modified Hodge test (MHT) and combined disk tests (CDT) were applied for blaNDM-1 MβL detection. Acinetobacter isolates with phenotypically confirmed MβLs production were subjected to a PCR assay to verify the presence of blaNDM-1 gene. The most obvious risk factors for acquisition of carbapenem resistance in VAP patients and treatment outcomes were also analyzed.

Results

Out of 64 Acinetobacter isolates, 42 (65.6%) proved to be blaNDM-1 positive. The sensitivity and specificity of MHT were 52.38% and 41.67%, while for CDT they were 92.86% and 83.33%, respectively. Acinetobacter isolates showed high susceptibility to colistin (85.7%). The clinical response was better among VAP patients who received combined carbapenem plus colistin therapy than those who received colistin alone. Relapse of infection was detected in 12.5% (8/64) of VAP cases. The reported mortality reached 46.8% (30/64) of which 27 (64.3%) were infected with blaNDM-1-positive isolates. Prolonged duration of mechanical ventilation, longer hospital and ICU stays, and prior exposure to antibiotic therapy were by far the most important factors predisposing to carbapenem resistance among VAP patients.

Conclusion

A worldwide spread of Acinetobacter spp. expressing carbapenemases represents a significant threat to the medical community. The current study addressed the high prevalence of blaNDM-1-producing Acinetobacter isolates among late-onset VAP patients.

Guidelines for Antibiotic Prescription in Intensive Care Unit

How to cite this article: Khilnani GC, Zirpe K, Hadda V, Mehta Y, Madan K, Kulkarni A, Mohan A, Dixit S, Guleria R, Bhattacharya P. Guidelines for Antibiotic Prescription in Intensive Care Unit. Indian Journal of Critical Care Medicine 2019;23 (Suppl 1):1-63.

Intravenous Colistin Monotherapy versus Combination Therapy against Carbapenem-Resistant Gram-Negative Bacteria Infections: Meta-Analysis of Randomized Controlled Trials

This meta-analysis aims to compare intravenous colistin monotherapy and colistin-based combination therapy against carbapenem-resistant gram-negative bacteria (GNB) infections. PubMed, Embase, and Cochrane databases were searched up to July 2018. Only randomized controlled trials (RCTs) evaluating colistin alone and colistin-based combination therapy in the treatment of carbapenem-resistant GNB infections were included. The primary outcome was all-cause mortality. Five RCTs including 791 patients were included. Overall, colistin monotherapy was associated with a risk ratio (RR) of 1.03 (95% confidence interval (CI), 0.89–1.20, I² = 0%) for all-cause mortality compared with colistin-based combination therapy. The non-significant difference was also detected in infection-related mortality (RR, 1.23, 95% CI, 0.91–1.67, I² = 0%) and microbiologic response (RR, 0.86, 95% CI, 0.72–1.04, I² = 62%). In addition, no significant difference was observed in the subgroup analysis—high or low dose, with or without a loading dose, carbapenem-resistant Acinetobacter baumannii infections, and in combination with rifampicin. Finally, colistin monotherapy was not associated with lower nephrotoxicity than colistin combination therapy (RR, 0.98; 95% CI, 0.84–1.21, I² = 0%). Based on the analysis of the five RCTs, no differences were found between colistin monotherapy and colistin-based combination therapy against carbapenem-resistant GNB infections, especially for A. baumannii infections.

Emergence of Carbapenem Resistant Non-Fermenting Gram-Negative Bacilli Isolated in an ICU of a Tertiary Care Hospital

INTRODUCTION

The emergence and spread of Multi-Drug Resistant (MDR) Non-Fermenting Gram-Negative Bacilli (NFGNB) in Intensive Care Units (ICU) and their genetic potential to transmit diverse antibiotic resistance regardless of their ability to ferment glucose poses a major threat in hospitals. The complex interplay of clonal spread, persistence, transmission of resistance elements and cell-cell interaction leads to the difficulty in controlling infections caused by these multi drug-resistant strains. Among non-fermenting Gram-negative rods, the most clinically significant species Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia are increasingly acquiring resistant to carbapenems. Carbapenems once considered as a backbone of treatment of life threatening infections appears to be broken as the resistance to carbapenems is on rise.

AIM

To document the prevalence of carbapenem resistance in non-fermenting Gram-negative bacilli isolated from patients with respiratory tract infections in the ICU of Himalayan Institute of Medical Sciences, Dehradun.

MATERIALS AND METHODS

This is a cross-sectional study conducted in ICU patients between October 2015 to March 2016. A total of 366 lower respiratory tract samples were collected from 356 patients with clinical evidence of lower respiratory tract infections in form of Endotracheal (ET) aspirate, Tracheal Tube (TT) aspirate and Bronchoalveolar Lavage (BAL) specimen. Organism identification and the susceptibility testing was done by using an automated system VITEK 2.

RESULTS

Out of 366 samples received 99 NFGNB were isolated and most common sample was ET aspirate sample 256 (64.5%). Acinetobacter baumannii was the most common NFGNB isolated 63 (63.63%) followed by Pseudomonas aeruginosa 25 (25.25%), Elizabethkingia meningoseptica seven (7.07%) and Strenotrophomonas maltophilia four (4.04%). We observed that 90.5% Acinetobacter baumannii were resistant to imipenem and 95.2% resistant to meropenem, Pseudomonas aeruginosa came out to be 52% resistant to imipenem and 56% resistant to meropenem while Stenotrophomonas maltophilia and Elizabethkingia meningoseptica were 100% resistant to carbapenems as they are intrinsically resistant to carbapenems.

CONCLUSION

The resistance rate of carbapenems for NFGNB infections is very high in our study and variable in different regions. Overall carbapenem resistance is on rise. So, the infection control team and microbiologist needs to work together to determine the risk carried by multi drug resistant non-fermenting gram-negative infections and the resistance surveillance programs are mandatory to control these bacteria in ICU settings.

National Survey of Thai Infectious Disease Physicians on Treatment of Carbapenem-Resistant Acinetobacter baumannii Ventilator-Associated Pneumonia: The Role of Infection Control Awareness

OBJECTIVE To evaluate the expected and treatment outcomes of Thai infectious disease physicians (IDPs) regarding carbapenem-resistant Acinetobacter baumannii (CRAB) ventilator-associated pneumonia (VAP) METHODS From June 1, 2014, to March 1, 2015, survey data regarding the expected and clinical success rates of CRAB VAP treatment were collected from all Thai IDPs. The expected success rate was defined as the expectation of clinical response after CRAB VAP treatment for the given case scenario. Clinical success rate was defined as the overall reported success rate of CRAB VAP treatment based on the clinical practice of each IDP. The expected and clinical success rates were divided into low (80%) categories and were then compared with standard clinical response rates archived in the existing literature. RESULTS Of 183 total Thai IDPs, 111 (60%) were enrolled in this study. The median expected and clinical success rates were 68% and 58%, respectively. Using multivariate analysis, we determined that working in a hospital that implemented the standard intervention combined with an intensified infection control (IC) intervention for CRAB (adjusted odds ratio [aOR], 3.01; 95% confidence interval [CI], 1.17-7.73; P=.02) was associated with standard and high expected rates (>60%). Being a board-certified IDP (aOR, 5.76; 95% CI, 2.16-15.37; P60%). We identified a significant correlation between expected and clinical success rates (r=0.58; P<.001). CONCLUSIONS Awareness of IC among IDPs can improve physicians' expected and clinical success rates for CRAB VAP treatment, and treatment experience impacts overall treatment success. Infect. Control Hosp. Epidemiol. 2015;37(1):61-69.

Nosocomial Acinetobacter pneumonia: Treatment and prognostic factors in 356 cases

BACKGROUND AND OBJECTIVE

Acinetobacter baumannii and A. baumannii/calcoaceticus complex are commonly encountered pathogens in nosocomial infections. This study aimed to evaluate the treatment and prognostic risk factors in nosocomial pneumonia caused by these microorganisms.

METHODS

The study was conducted retrospectively in Uludag University Hospital and included 356 adult non-neutropenic patients with nosocomial pneumonia.

RESULTS

Of the subjects, 94.9% (n = 338) had ventilator-associated pneumonia. The clinical response rate was 57.2%, the 14-day mortality 39.6% and the 30-day mortality 53.1%. The significant independent risk factors for the 30-day mortality were severe sepsis (OR, 2.60; 95% CI: 1.49-4.56; P = 0.001), septic shock (OR, 6.12; 95% CI: 2.75-13.64; P < 0.001), APACHE II score ≥ 20 (OR, 2.12; 95% CI: 1.28-3.50; P = 0.003) and empiric monotherapy (OR, 1.63; 95% CI: 1.00-2.64; P = 0.048). Multi-trauma (OR, 2.50; 95% CI: 1.11-5.68; P = 0.028) was found to be a protective factor. In patients with a clinical pulmonary infection score (CPIS) > 6 on the third day of treatment, both the 14- and 30-day mortality rates were high (P < 0.001, P < 0.001). Also, the 14- and 30-day mortality rates were significantly higher in the patients treated with empiric monotherapy compared with combination therapy (48/93 (51.6%)-46/123 (37.4%), P = 0.037 and 62/93 (66.7%)-65/123 (52.8%), P = 0.041, respectively) in pneumonia caused by imipenem-resistant strains.

CONCLUSION

Mortality rates were high in pneumonia caused by imipenem-resistant A. baumannii or A. baumannii/calcoaceticus complex. In the units with a high level of carbapenem resistance, antibiotic combinations should be considered for empiric therapy.