Risk factors for carbapenem-resistant Acinetobacter baumannii infections at a tertiary care hospital in New Caledonia, South Pacific

Correlation between Carbapenem Consumption and Carbapenems Susceptibility Profiles of Acinetobacter baumannii and Pseudomonas aeruginosa in an Academic Medical Center in Thailand

The emergent issue of carbapenem-resistant Acinetobacter baumannii (A. baumannii) and Pseudomonas aeruginosa (P. aeruginosa) is a major problem in Thailand. The wide use of carbapenems can increase selective pressure of bacterial resistance. The objective of this study was to determine the relationship between carbapenem consumption and the susceptibility rates of A. baumannii and P. aeruginosa, including multi-drug resistance (MDR) strains. This was a retrospective study. Carbapenem consumption and susceptibility profiles were collected from 2007 to 2013 at the Her Royal Highness Princess Maha Chakri Sirindhorn Medical Center, Thailand. We found that the susceptibility rate of A. baumannii to imipenem and meropenem from the sputum and the bronchoalveolar lavage (BAL) specimens was significantly decreased during the study period, but no significant change was found in the P. aeruginosa data. The relationship between carbapenem consumption and the susceptibility rate of A. baumannii had a clear association with the use of ertapenem. We found a statistically significant negative correlation between ertapenem consumption and the susceptibility rate of A. baumannii to imipenem (r = −0.91; p = 0.004) and meropenem (r = −0.97; p = 0.000) in the data from the non-ICU wards. In addition, imipenem use had a moderate negative correlation with the MDR P. aeruginosa data but no statistical significance (r = −0.714; p > 0.05). In conclusion, our study suggested there is an association between carbapenem use and the susceptibility of A. baumannii and P. aeruginosa. Notwithstanding this, information on ecological factors should be considered for further study. These findings showed the need to optimize the carbapenem prescription policy. Avoiding carbapenem overuse and rethinking the appropriate initial therapy might decrease the rate of resistant organisms.

Deciphering Multidrug-Resistant Acinetobacter baumannii from a Pediatric Cancer Hospital in Egypt

Infection by multidrug-resistant (MDR) Acinetobacter baumannii is one of the major causes of hospital-acquired infections worldwide. The ability of A. baumannii to survive in adverse conditions as well as its extensive antimicrobial resistance make it one of the most difficult to treat pathogens associated with high mortality rates. The aim of this study was to investigate MDR A. baumannii that has spread among pediatric cancer patients in the Children’s Cancer Hospital Egypt 57357. Whole-genome sequencing was used to characterize 31 MDR A. baumannii clinical isolates. Phenotypically, the isolates were MDR, with four isolates showing resistance to the last-resort antibiotic colistin. Multilocus sequence typing showed the presence of eight clonal groups, two of which were previously reported to cause outbreaks in Egypt, and one novel sequence type (ST), Oxf-ST2246. Identification of the circulating plasmids showed the presence of two plasmid lineages in the isolates, strongly governed by sequence type. A large number of antimicrobial genes with a range of resistance mechanisms were detected in the isolates, including β-lactamases and antibiotic efflux pumps. Analysis of insertion sequences (ISs) revealed the presence of ISAba1 and ISAba125 in all the samples, which amplify β-lactamase expression, causing extensive carbapenem resistance. Mutation analysis was used to decipher underlying mutations responsible for colistin resistance and revealed novel mutations in several outer membrane proteins, in addition to previously reported mutations in pmrB. Altogether, understanding the transmissibility of A. baumannii as well as its resistance and virulence mechanisms will help develop novel treatment options for better management of hospital-acquired infections.

IMPORTANCEAcinetobacter baumannii represents a major health threat, in particular among immunocompromised cancer patients. The rise in carbapenem-resistant A. baumannii, and the development of resistance to the last-resort antimicrobial agent colistin, complicates the management of A. baumannii outbreaks and increases mortality rates. Here, we investigate 31 multidrug resistant A. baumannii isolates from pediatric cancer patients in Children’s Cancer Hospital Egypt (CCHE) 57357 via whole-genome sequencing. Multilocus sequence typing (MLST) showed the presence of eight clonal groups including a novel sequence type. In silico detection of antimicrobial-resistant genes and virulence factors revealed a strong correlation between certain virulence genes and mortality as well as several point mutations in outer membrane proteins contributing to colistin resistance. Detection of CRISPR/Cas sequences in the majority of the samples was strongly correlated with the presence of prophage sequences and associated with failure of bacteriophage therapy. Altogether, understanding the genetic makeup of circulating A. baumannii is essential for better management of outbreaks.

Prevention and control of highly antibiotic-resistant bacteria in a Pacific territory: Feedback from New Caledonia between 2004 and 2020

OBJECTIVE

Carbapenemase-producing Enterobacteriaceae (CRE) and Enterococcus faecium resistant to vancomycin (VRE) constitute major threats to public health worldwide. The Pacific area is concerned and has implemented strategies to control antimicrobial resistance (AMR). However, accurate epidemiological data are rarely reported. Our study aimed to present the strategies applied to prevent and control the spread of highly resistant bacteria in the Pacific territory of New Caledonia.

PATIENTS AND METHODS

Cohort prospective study of all cases of highly resistant bacteria (HRB) isolated in New Caledonia from September 2004 to December 2020. Evaluation of the impact of the infection control measures implemented in healthcare settings: screening strategy, cohorting unit, IT tools and control of antibiotic prescriptions.

RESULTS

A total of 346 patients with HRB were identified. Most of them (63.0%) were infected or colonized by VRE (n=218) and 128 by CRE. While the number of CREs significantly increased from 2013 to 2020 (P<0.0001), control procedures have limited their dissemination. Most patients were colonized by IMP-4-CRE (n=124/128). The incidence density of VRE significantly decreased from 38.52 for 100,000 hospitalisation-days in 2015 to 4.19 for 100,000 hospitalisation-days in 2019 due to systematic screening of patients before sanitary repatriation from Australia and cohorting implementation. The risk of VRE diffusion is now well under control.

CONCLUSIONS

Our study confirms that it is possible to control the spread of AMR in a circumscribed territory by means of a global control strategy involving screening, cohorting unit, IT tools and antibiotic prescription controls.

Antibiotic Resistance in Pacific Island Countries and Territories: A Systematic Scoping Review

Several studies have investigated antimicrobial resistance in low- and middle-income countries, but to date little attention has been paid to the Pacific Islands Countries and Territories (PICTs). This study aims to review the literature on antibiotic resistance (ABR) in healthcare settings in PICTs to inform further research and future policy development for the region. Following the PRISMA-ScR checklist health databases and grey literature sources were searched. Three reviewers independently screened the literature for inclusion, data was extracted using a charting tool and the results were described and synthesised. Sixty-five studies about ABR in PICTs were identified and these are primarily about New Caledonia, Fiji and Papua New Guinea. Ten PICTs contributed the remaining 21 studies and nine PICTs were not represented. The predominant gram-positive pathogen reported was community-acquired methicillin resistant S. aureus and the rates of resistance ranged widely (>50% to <20%). Resistance reported in gram-negative pathogens was mainly associated with healthcare-associated infections (HCAIs). Extended spectrum beta-lactamase (ESBL) producing K. pneumoniae isolates were reported in New Caledonia (3.4%) and Fiji (22%) and carbapenem resistant A. baumannii (CR-ab) isolates in the French Territories (24.8%). ABR is a problem in the PICTs, but the epidemiology requires further characterisation. Action on strengthening surveillance in PICTs needs to be prioritised so strategies to contain ABR can be fully realised.

Co-Colonization with Neisseria species Is a Risk Factor for Prolonged Colonization with Multidrug-Resistant Acinetobacter baumannii in the Respiratory Tract

Multidrug-resistant Acinetobacter baumannii (MDRAB) colonization increases the risk of bacterial spread in the hospital setting. The impact of clinical factors, including antibiotic use, on prolongation of MDRAB colonization has not been investigated. Patients with respiratory tract MDRAB detected using culture were enrolled in this study. Long-term colonizers and short-term colonizers were defined as patients whose colonization periods were >30 days or ≤30 days, respectively. Clinical data were abstracted from medical records. MDRAB was isolated in 34 patients. There were 13 long-term colonizers and 9 short-term colonizers. Twelve patients were lost to follow-up and excluded from the study. There were no significant differences in average leukocyte counts, numbers of antibiotic classes administered, duration of antibiotic use in the 30 days following colonization, or rates of central catheterization or mechanical ventilation between the 2 groups. Long-term colonizers carried Neisseria species (spp.) more frequently in the 30 days following colonization than short-term colonizers (7/13 vs 1/9, p = 0.01); however, this was not the case prior to colonization with MDRAB (5/13 vs 1/9, p = 0.33). The 90-day MDRAB colonization rates for Neisseria-negative patients and Neisseria-positive patients were 10.0% and 83.3%, respectively (P < 0.01). Prolonged MDRAB colonization in the respiratory tract was associated with Neisseria spp. co-colonization.

Epidemiology and Cytokine Levels among Children with Nosocomial Multidrug-Resistant Acinetobacter baumannii Complex in a Tertiary Hospital of Eastern China

BACKGROUND AND AIM

The present study was aimed at assessing the characteristics of children with nosocomial multidrug-resistant Acinetobacter baumannii complex (MDR ABC) in a tertiary hospital of eastern China. MDR ABC poses a serious threat to public health. However, information on nosocomial MDR ABC in children is lacking.

METHOD

This study retrospectively reviewed the cases in a tertiary hospital of eastern China between January 1, 2011, and December 31, 2014 (excluding outpatients).

RESULTS

A total of 377 non-duplicated nosocomial ABC isolates were collected from various samples including 200 (53.1%) MDR ABC isolates. Moreover, 158 of the 200 MDR ABC isolates were collected from intensive care units (ICUs; MDR constituent ratios, 62.5%), while 98 of the 200 MDR ABC isolates were collected from children older than 1 year (MDR constituent ratios, 62.8%). Multivariate logistic analysis revealed that being in the surgical intensive care unit (SICU), prolonged hospital stay, surgical intervention, and mechanical ventilation were independent risk factors for MDR acquisition among children with nosocomial ABC. The interleukin (IL)-6 level of children with nosocomial MDR ABC was significantly lower than that of the children with nosocomial non-MDR ABC.

CONCLUSION

Nosocomial MDR ABC infection is a serious concern in pediatric patients. Being in the SICU, prolonged hospital stay, surgical intervention, and mechanical ventilation increased the risk of nosocomial MDR ABC. IL-6 might be involved in developing nosocomial MDR ABC among children.

Treatment for patients with multidrug resistant Acinetobacter baumannii pulmonary infection

Bacterial infections are common but have become increasingly resistant to drugs. The aim of the present study was to examine the combined treatment of traditional Chinese and Western medicine in 30 cases of pulmonary infection with multidrug resistant Acinetobacter baumannii. Patients were divided into groups A and B according to drug treatments. Cefoperazone or sulbactam and tanreqing were administered in group A, and cefoperazone or sulbactam in group B. The curative effect and prognosis of the two groups were recorded and the remaining treatments were performed routinely in the clinic. For the combined therapy group, which was administered sulperazone and tanreqing, 8 patients were recovered, 6 patients had significant effects, 3 patients exhibited some improvement and 1 patient had no response. One of the patients did not survive after 28 days. By contrast, there were 4 patients that were successfully treated, 3 patients with significant effects, 2 patients with some improvement and 2 patients had no response in the sulperazone group, and 4 patients did not survive after 28 days. In conclusion, the combined therapy of cefoperazone or sulbactam supplemented with tanreqing was identified to be more effective than cefoperazone or sulbactam as monotherapy, for treating multidrug resistant Acinetobacter baumannii.

Molecular Epidemiology and Characterization of Genotypes of Acinetobacter baumannii Isolates from Regions of South China

The aim of this study was to analyze the molecular epidemiologic characteristics of Acinetobacter baumannii. A total of 398 isolates were collected in 7 regions of South China from January to June of 2012. Drug sensitivity was tested toward 15 commonly used antibiotics; thus, 146 multi-drug-resistant strains (resistant to more than 7 drugs) were identified, representing 36.7% of all isolates. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used for molecular subtyping. According to the PFGE results (with a cutoff of 70% similarity for the DNA electrophoretic bands), 146 strains were subdivided into 15 clusters, with cluster A being the largest (33.6%, distributed in all districts except Jiaxing). Cluster B was also widespread and included 14.4% of all strains. In addition, MLST results revealed 11 sequence types (ST), with ST208 being the most prevalent, followed by ST191 and ST729. Furthermore, 4 novel alleles and 6 novel STs were identified. Our results showed that multi-drug-resistant A. baumannii in South China shares the origin with other widespread strains in other countries. The nosocomial infections caused by A. baumannii have been severe in South China. Continuous monitoring and judicious antibiotic use are required.

Molecular identification of Acinetobacter baumannii isolated from intensive care units and their antimicrobial resistance patterns

Background:

Acinetobacter baumannii is one of the most important pathogens in hospital-acquired infections especially in intensive care units (ICUs). This opportunistic pathogen can be easily isolated from water, soil, and hospital facilities. A. baumannii as a nosocomial opportunistic pathogen is resistant to a wide range of antibiotics and responsible for multiple infections, including bacteremia, pneumonia, meningitis, urinary tract infections, and surgical wounds. The aim of this study was to determine frequency and resistance patterns of A. baumannii isolated in ICUs of Isfahan Hospitals.

Materials and Methods:

During 1 year period (2012-2013), 350 specimens were collected from ICUs of Isfahan hospitals. The isolates were characterized as A. baumannii by conventional phenotypic, biochemical tests and confirmed by PCR for OXA-51-like gene. Susceptibility of isolates was determined by standard disk diffusion method according to CLSI.

Results:

From total of 350 specimens, 43 isolates were A. baumannii. The antimicrobial patterns of isolates showed that 53.5% of isolates were resistant to amikacin, 83.7% to tetracyclin, 86% to ceftazidime, 90.7% to Trimethoprim sulfametoxazol, 93% to imipenem, cefepime, meropenem, ampicillin–sulbactam. All isolates were resistant to ciprofloxacin.

Conclusion:

This study showed a high resistance of A. baumannii to a wide range of antimicrobial agent. It is necessary to adopt appropriate strategies to control the spread of the bacteria in care unit centers and wards.

Mechanisms of β-lactam antimicrobial resistance and epidemiology of major community- and healthcare-associated multidrug-resistant bacteria

Alexander Fleming's discovery of penicillin heralded an age of antibiotic development and healthcare advances that are premised on the ability to prevent and treat bacterial infections both safely and effectively. The resultant evolution of antimicrobial resistant mechanisms and spread of bacteria bearing these genetic determinants of resistance are acknowledged to be one of the major public health challenges globally, and threatens to unravel the gains of the past decades. We describe the major mechanisms of resistance to β-lactam antibiotics - the most widely used and effective antibiotics currently - in both Gram-positive and Gram-negative bacteria, and also briefly detail the existing and emergent pharmacological strategies to overcome such resistance. The global epidemiology of the four major types of bacteria that are responsible for the bulk of antimicrobial-resistant infections in the healthcare setting - methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Enterobactericeae, and Acinetobacter baumannii - are also briefly described.

Risk factors of mortality in patients with carbapenem-resistant Acinetobacter baumannii bacteremia

BACKGROUND/PURPOSE

Identification of risks of mortality for carbapenem-resistant Acinetobacter baumannii (CRAB), with early implementation of an appropriate therapy, is crucial for the patients' outcome. The aim of this study was to survey mortality risk factors in 182 patients with CRAB bacteremia in a medical center in Taiwan.

METHODS

A total of 182 isolates of CRAB bacteremia were collected from 2009 to 2012 in Mackay Memorial Hospital, Taipei, Taiwan These isolates were identified by using the genotypic method. Risk of attributable mortality analysis was carried out with a Cox proportional hazards model.

RESULTS

The 182 CRAB isolates belonged to 38 different pulsotypes. The attributable mortality rate of the 182 patients was 58.24%. The risk factors for attributable mortality included intensive care unit stay [hazard ratio (HR): 2.27; p = 0.011], an Acute Physiology and Chronic Health Evaluation II score of >20 (HR: 2.19; p < 0.001), respiratory tract as the origin of bacteremia (HR: 3.40; p < 0.001), and previous use of ceftriaxone (HR: 2.51; p = 0.011). The appropriateness of antimicrobial therapy was 18.87% (20/106) in the mortality group versus 88.16% (67/76) in the survivor group (p < 0.001). The sensitivity of CRAB to colistin was 100% and to tigecycline was 40.11%.

CONCLUSION

The risk factors for mortality for CRAB included intensive care unit stay, a high Acute Physiology and Chronic Health Evaluation II score, respiratory tract as the origin of bacteremia, and previous use of ceftriaxone. Early implementation of an antimicrobial agent that had the highest in vitro activity against CRAB in patients at risk of CRAB bacteremia and high mortality may improve their outcome.

Risk factors and outcomes of infections caused by extremely drug-resistant gram-negative bacilli in patients hospitalized in intensive care units

BACKGROUND

Extremely drug-resistant gram-negative bacilli (XDR-GNB) increasingly cause health care-associated infections (HAIs) in intensive care units (ICUs).

METHODS

A matched case-control (1:2) study was conducted from February 2007 to January 2010 in 16 ICUs. Case and control subjects had HAIs caused by GNB susceptible to ≤1 antibiotic versus ≥2 antibiotics, respectively. Logistic and Cox proportional hazards regression assessed risk factors for HAIs and predictors of mortality, respectively.

RESULTS

Overall, 103 case and 195 control subjects were enrolled. An immunocompromised state (odds ratio [OR], 1.55; P = .047) and exposure to amikacin (OR, 13.81; P < .001), levofloxacin (OR, 2.05; P = .005), or trimethoprim-sulfamethoxazole (OR, 3.42; P = .009) were factors associated with XDR-GNB HAIs. Multiple factors in both case and control subjects significantly predicted increased mortality at different time intervals after HAI diagnosis. At 7 days, liver disease (hazard ratio [HR], 5.52), immunocompromised state (HR, 3.41), and bloodstream infection (HR, 2.55) predicted mortality; at 15 days, age (HR, 1.02 per year increase), liver disease (HR, 3.34), and immunocompromised state (HR, 2.03) predicted mortality; and, at 30 days, age (HR, 1.02 per 1-year increase), liver disease (HR, 3.34), immunocompromised state (HR, 2.03), and hospitalization in a medical ICU (HR, 1.85) predicted mortality.

CONCLUSION

HAIs caused by XDR-GNB were associated with potentially modifiable factors. Age, liver disease, and immunocompromised state, but not XDR-GNB HAIs, were associated with mortality.

Correlation between antibiotic consumption and carbapenem-resistant Acinetobacter baumannii causing health care-associated infections at a hospital from 2005 to 2010

BACKGROUND/PURPOSE

This study investigated the correlation between antibiotic consumption and the incidence of health care-associated infections (HCAIs) caused by imipenem-resistant Acinetobacter baumannii (IRAB) at a hospital in Taiwan from 2005 to 2010.

METHODS

Data on annual consumption (defined daily dose per 1000 patient-days) of extended-spectrum cephalosporins, β-lactam-β-lactamase inhibitor combinations, carbapenems, aminoglycosides, and fluoroquinolones from 2005 to 2010 were analyzed. Yearly aggregated data on the number of nonduplicate clinical IRAB isolates causing HCAI were collected. The incidence rates of HCAI caused by IRAB were defined as the number of patients infected with IRAB per 1000 inpatient-days.

RESULTS

The trend of total consumption (defined daily dose per 1000 patient-days) of extended-spectrum cephalosporins, carbapenems, and fluoroquinolones was significantly increased, but the use of aminoglycosides decreased during 2005 to 2010. During the same period, the incidence of HCAI caused by IRAB gradually increased. The consumptions of carbapenems and fluoroquinolones were positively correlated with the incidence of HCAI caused by IRAB. There was no significant association between the use of extended-spectrum cephalosporins, β-lactam-β-lactamase inhibitor combinations, and aminoglycosides and the incidence of HCAI caused by IRAB.

CONCLUSION

The increasing use of carbapenems and fluoroquinolones was associated with the increasing incidence of HCAI caused by IRAB.