Extensively drug-resistant Acinetobacter baumannii and Proteeae association in a Romanian intensive care unit: risk factors for acquisition

Risk factors for multidrug-resistant and extensively drug-resistant Acinetobacter baumannii infection of patients admitted in intensive care unit: a systematic review and meta-analysis

BACKGROUND

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter baumannii infections pose challenges for clinical treatment and cause high mortality, particularly in intensive care units (ICUs).

AIM

To systematically summarize and analyse the risk factors for MDR/XDR A. baumannii-infected patients admitted to ICUs.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for eligible original studies published in English before October 2023. Meta-analysis was conducted where appropriate, with mean differences (MDs) and odds ratios (ORs) calculated for continuous and nominal scaled data. The quality of included studies was assessed using the Newcastle-Ottawa Scale (NOS).

FINDINGS

Ten studies reporting 1199 ICU patients (604 from general ICUs, 435 from neonatal ICUs, and 160 from paediatric ICUs) from eight countries were included in our analysis. Risk factors associated with MDR A. baumannii infection among patients admitted to general ICUs included high Acute Physiology And Clinical Health II (APACHE Ⅱ) score (mean difference (MD): 7.52; 95% confidence interval (CI): 3.24-11.80; P = 0.0006), invasive procedures (odds ratio (OR): 3.47; 95% CI: 1.70-7.10; P = 0.0006), longer ICU stay (MD: 3.40; 95% CI: 2.94-3.86; P < 0.00001), and use of antibiotics (OR: 2.69; 95% CI: 1.22-5.94; P = 0.01). In the sub-group analysis, longer neonatal ICU stay (MD: 16.88; 95% CI: 9.79-23.97; P < 0.00001) was associated with XDR A. baumannii infection.

CONCLUSION

Close attention should be paid to patients with longer ICU stays, undergoing invasive procedures, using antibiotics, and with high APACHE Ⅱ scores to reduce the risk of MDR and XDR A. baumannii infections.

Healthcare-Associated Bloodstream Infections Due to Multidrug-Resistant Acinetobacter baumannii in COVID-19 Intensive Care Unit: A Single-Center Retrospective Study

Healthcare-associated infections are an emerging cause of morbidity and mortality in COVID-19 intensive care units (ICUs) worldwide, especially those caused by multidrug-resistant (MDR) pathogens. The objectives of this study were to assess the incidence of bloodstream infections (BSIs) among critically ill COVID-19 patients and to analyze the characteristics of healthcare-associated BSIs due to MDR Acinetobacter baumannii in an COVID-19 ICU. A single-center retrospective study was conducted at a tertiary hospital during a 5-month period. The detection of carbapenemase genes was performed by PCR and genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multilocus-sequence typing. A total of 193 episodes were registered in 176 COVID-19 ICU patients, with an incidence of 25/1000 patient-days at risk. A. baumannii was the most common etiological agent (40.3%), with a resistance to carbapenems of 100%. The blaOXA-23 gene was detected in ST2 isolates while the blaOXA-24 was ST636-specific. PFGE revealed a homogeneous genetic background of the isolates. The clonal spread of OXA-23-positive A. baumannii is responsible for the high prevalence of MDR A. baumannii BSIs in our COVID-19 ICU. Further surveillance of resistance trends and mechanisms is needed along with changes in behavior to improve the implementation of infection control and the rational use of antibiotics.

Bacterial and Fungal Superinfections in COVID-19 Patients Hospitalized in an Intensive Care Unit from Timișoara, Romania

PURPOSE

Critically ill patients hospitalized in the intensive care unit (ICU) have an increased infection risk. The aim of this study was to determine the bacterial and fungal superinfections rate in Coronavirus disease 2019 (COVID-19) patients stationed in the ICU, identify risk factors associated with their development and to determine whether superinfection plays a role in patients' outcome in this population.

PATIENTS AND METHODS

In this retrospective, non-interventional, single centre, cohort study, medical records of 302 consecutive patients with SARS-COV-2 pneumonia admitted into the COVID-19 ICU of the largest university hospital from Western Romania between October 2020 and May 2021, were reviewed, of whom 236 patients met the inclusion criteria.

RESULTS

One hundred and nineteen patients developed a superinfection ≥48 h after being admitted to the hospital. Superinfection rate in the ICU was 50.42%. Coagulase-negative Staphylococci (CoNS) and Enterococcus spp. were predominantly isolated from blood cultures, while Acinetobacter baumannii, Staphylococcus aureus and Candida spp. from tracheobronchial aspirates. Significant independent risk factors regarding bacterial/fungal superinfection in COVID-19 patients were obtained for the following variables: number of days of central venous catheter (HR = 1.13 [1.07-1.20], p < 0.001) and prior administration of corticosteroids (HR = 2.80 [1.33-5.93], p = 0.007). Four independent predictive risk factors were associated with unfavorable outcome: age (HR = 1.07 [95% CI 1.03-1.12], p = 0.001); Carmeli Score (HR = 6.09 [1.18-31.50], p = 0.031); body mass index (HR = 1.11 [1.02-1.21], p = 0.011) and the presence of a central venous catheter (HR = 6.49 [1.93-21.89], p = 0.003).

CONCLUSION

The superinfection rate in COVID-19 patients was high in this study group. Exogenous risk factors were associated with superinfection more than endogenous factors. Only a small percentage of uninfected COVID-19 patients were not prescribed antibiotics during their hospitalization, raising serious concerns regarding the judicious prescribing of antibiotics in viral infections.

Association of Proteus mirabilis and Providencia stuartii Infections with Diabetes

Background and Objectives: Proteus and Providencia are related genera of opportunistic pathogens belonging to the Morganellaceae family, often a cause of infections in the immunocompromised hosts, such as diabetic patients. Their clinical significance has increased due to their intrinsic resistance to polymyxins, which is often associated with acquired resistance mechanisms. In this study we evaluated the infections caused by Proteus mirabilis and Providencia stuartii in two groups of patients, with diabetes (group 1) and without diabetes (group 2) admitted to the intensive care unit and surgical wards. The infections were investigated in terms of infection type, risk factors, clinical course, predictive factors for unfavourable outcomes and antibiotic resistance profile. Materials and Methods: An observational, retrospective, cross-sectional study was conducted, comprising all patients infected with these pathogens. Bacterial identification and antibiotic sensitivity testing were performed using the Vitek2C automated system. Results: Comparison of the two groups showed that the statistically significant common infectious risk factors were found less frequently among diabetic patients when compared with non-diabetic patients, and that antimicrobial resistance was significantly lower in the diabetic patient group. However, survival rates did not differ between the two groups, drawing attention to the implications of diabetes as comorbidity. Additionally, with regard to the antibiotic resistance profile, 38.89% of P. stuartii strains isolated from diabetic patients belonged to the difficult-to-treat (DTR) phenotype, contributing to the severity of these infections compared with those caused by P. mirabilis, of which 32% were wild type strains and 0% were DTR phenotype. The DTR/extended spectrum beta-lactamase producing P. stuartii isolates more than doubled the risk of mortality, while the presence of nasogastric nutrition tripled the risk. Conclusions: P. stuartii infections that occurred in diabetic patients proved to be more difficult to treat, the majority of them being healthcare-associated bacteremias.

Epidemiology and Pattern of Resistance of Gram-Negative Bacteria Isolated from Blood Samples in Hospitalized Patients: A Single Center Retrospective Analysis from Southern Italy

BACKGROUND

Blood culturing remains the mainstream tool to inform an appropriate treatment in hospital-acquired bloodstream infections and to diagnose any bacteremia.

METHODS

A retrospective investigation on the prevalence of Gram-negative bacteria (GNB) and their resistance in hospitalized patients by age, sex, and units from blood cultures (BCs) was conducted from January 2018 to April 2020 at Sant'Elia hospital, Caltanissetta, southern Italy. We divided the patient age range into four equal intervals.

RESULTS

Multivariate demographic and microbiological variables did not show an association between bacteria distributions and gender and age. The distribution by units showed a higher prevalence of Klebsiella pneumoniae and Acinetobacter baumannii in the intensive care unit (ICU) and Escherichia coli in the non-intensive care units (non-ICUs). The analysis of antibiotic resistance showed that E. coli was susceptible to a large class of antibiotics such as carbapenem and trimethoprim-sulfamethoxazole. K. pneumoniae showed a significant susceptibility to colistin, tigecycline, and trimethoprim-sulfamethoxazole. From the survival analysis, patients with E. coli had a higher survival rate.

CONCLUSIONS

The authors stress the importance of the implementation of large community-level programs to prevent E. coli bacteremia. K. pneumoniae and E. coli susceptibility patterns to antibiotics, including in the prescription patterns of general practitioners, suggest that the local surveillance and implementation of educational programs remain essential measures to slow down the spread of resistance and, consequently, increase the antibiotic lifespan.

Distribution of NDM1 Carbapenemase-Producing Proteeae Strains on High-Risk Hospital Wards

Background

Carbapenem-resistant Proteeae (CRP) is a group of multidrug-resistant (MDR) microorganisms that raise special treatment problems due to their intrinsic resistance to colistin. In this study, our aim is to provide a phenotypic and molecular characterization of the carbapenemases secreted by CRP strains isolated from inpatients from an intensive care unit (ICU) and surgical wards, as well as the identification of the risk factors involved in their acquisition.

Methods

An observational, cross-sectional study was performed which included all Proteeae strains isolated in samples from inpatients on high-risk wards of the largest university hospital in Western Romania, from July 2017 to April 2019. Meropenem-resistant strains (N=65) with MIC ≥16 µg/mL were subjected to a singleplex PCR assay for the detection of blaNDM, blaVIM and blaCTX-M genes. The analysis of risk factors was performed by logistic regression.

Results

Out of 8317 samples that were processed, 400 Proteeae strains were isolated: 64% belonging to the genus Proteus, 26.75% to the genus Providencia and 9.25% to the genus Morganella. Most CRP strains (N=56) were of MBL type, and 55 had the blaNDM gene as the prevalent gene substrate. P. stuartii was the main species that provided the circulating MDR strains. Most CRP strains came from patients admitted to ICU, being isolated mainly from bronchial aspirates and blood cultures. Multivariate analysis revealed 3 independent risk factors – mechanical ventilation>96h (HR: 40.51 [13.65–120.25], p <0.001), tracheostomy (HR: 2.65 [1.14–6.17], p = 0.024) and prolonged antibiotic therapy (HR: 1.01 [1.00–1.02], p = 0.03).

Conclusion

There is a significant increase in the incidence of CR P. stuartii strains, the MBL-blaNDM type being predominant. These strains presented various other resistance mechanisms, being often extremely difficult to treat and led to an excess of lethality of 27.16%.

Detection of Extended-Spectrum β-Lactamase and Carbapenemase Activity in Gram-Negative Bacilli Using Liquid Chromatography - Tandem Mass Spectrometry

Purpose

Several mass spectrometry-based methods for antimicrobial sensitivity testing have been described in recent years. They offer an alternative to commercially available testing systems which were considered to have disadvantages in terms of cost- and time-efficiency. The aim of this study was to develop an LC-MS/MS-based antibiotic hydrolysis assay for evaluating antimicrobial resistance (AMR) of Gram-negative bacteria.

Materials and Methods

Four species of Gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Providencia stuartii and Acinetobacter baumannii) were tested against six antibiotics from three different classes: ampicillin, meropenem, imipenem, ceftazidime, ceftriaxone and cefepime. Bacterial suspensions from each species were incubated with a mixture of the six antibiotics. Any remaining antibiotic following incubation was measured using LC-MS/MS. The results were interpreted using measurements obtained for an E. coli strain sensitive to all antibiotics and expressed as percentage of hydrolyzed antibiotic. These were subsequently compared to commercially-available system for the bacteria identification and susceptibility testing.

Results

Overall, LC-MS/MS assay and commercial antimicrobial susceptibility platform results showed good agreement in terms of an organism being resistant/sensitive to an antibiotic. The time required to complete the LC-MS/MS-based hydrolysis test was under 5 h, significantly shorter that commercially available susceptibility testing platforms.

Conclusion

By using a sensitive strain for results interpretation and simultaneous use of multiple antibiotics, the proposed protocol offers improved robustness and multiplexing over previously described methods for antibiotic sensitivity testing. Nevertheless, further research is needed before routine assimilation of the method, especially for strains with intermediate resistance.

Risk factors for pneumonia caused by antimicrobial drug-resistant or drug-sensitive Acinetobacter baumannii infections: A retrospective study

Acinetobacter baumannii (AB) is one of the major types of infection in hospitalized patients. The development of AB resistance is becoming a global clinical challenge. To assist in the clinical management of AB-induced pneumonia, we designed the present retrospective observational study to investigate the risk factors for antimicrobial drug-resistant/-sensitive AB infections.A total of 214 individuals were reviewed, in which 100 and 55 pneumonia patients were infected with drug-resistant and drug-sensitive AB, respectively. Fifty-nine pneumonia patients without AB infection served as a control group. Age, sex, duration of hospital stay, prior surgery history, the presence of coinfection and companion diseases, routine blood test results, and immunogenicity were recorded. Logistic regression was performed to identify risk factors of AB infections.Multivariate analysis revealed that long duration of hospital stay (odds ratio = 1.091 [95% CI: 1.010-1.178], P = .027) and the absence of coinfection (odds ratio = 0.507 [95% CI: 0.265-0.970], P = .040) were independent risk factors for AB infections. Same pattern of risk factors was identified for the drug-sensitive group (long duration of hospital stay: odds ratio = 1.119 [95% CI: 1.016-1.232], P = .022; absence of coinfection: odds ratio = 0.328 [95% CI: 0.135-0.797], P = .014), while high blood urea nitrogen (odds ratio: 1.382 [95% CI: 1.042-1.833], P = .025) was the only significant risk factor for drug-resistant AB infection.Long duration of hospital stay and the absence of coinfection might predict AB infections in hospitalized patients. Antimicrobial drug-resistant and drug-sensitive AB infections possess different risk factor profiles. A poor kidney function may be predictive of drug-resistant AB infection. Further prospective studies are required to validate our findings.

A prospective multicenter study on the evaluation of antimicrobial resistance and molecular epidemiology of multidrug-resistant Acinetobacter baumannii infections in intensive care units with clinical and environmental features

BACKGROUND

Multidrug-resistant (MDR) Acinetobacter baumannii infections are considered as emerging nosocomial infections particularly in patients hospitalized in intensive care units (ICUs). Therefore, reliable detection of MDR strains is crucial for management of treatment but also for epidemiological data collections. The purpose of this study was to compare antimicrobial resistance and the clonal distribution of MDR clinical and environmental A. baumannii isolates obtained from the ICUs of 10 different hospitals from five geographical regions of Turkey in the context of the demographic and clinical characteristics of the patients.

METHODS

A multicenter-prospective study was conducted in 10 medical centers of Turkey over a 6 month period. A total of 164 clinical and 12 environmental MDR A. baumannii isolates were included in the study. Antimicrobial susceptibility testing was performed for amikacin (AN), ampicillin-sulbactam (SAM), ceftazidime (CAZ), ciprofloxacin (CIP), imipenem (IMP) and colistin (COL) by microdilution method and by antibiotic gradient test for tigecycline (TIG). Pulsed-field gel electrophoresis (PFGE) was performed to determine the clonal relationship between the isolates. The detection of the resistance genes, bla_OXA-23, bla_OXA-24, bla_OXA-51, bla_OXA-58, bla_IMP, bla_NDM, bla_KPC, bla_OXA-48 and bla_PER-1 was carried out using the PCR method.

RESULTS

The mortality rate of the 164 patients was 58.5%. The risk factors for mortality included diabetes mellitus, liv1er failure, the use of chemotherapy and previous use of quinolones. Antimicrobial resistance rates for AN, SAM, CAZ, CIP, IMP, COL and TIG were 91.8%, 99.4%, 99.4%, 100%, 99.4%, 1.2% and 1.7% respectively. Colistin showed the highest susceptibility rate. Four isolates did not grow on the culture and were excluded from the analyses. Of 172 isolates, 166 (96.5%) carried bla_OXA-23, 5 (2.9%) bla_OXA-58 and one isolate (0.6%) was positive for both genes. The frequency of bla_PER-1 was found to be 2.9%. None of the isolates had bla_IMP, bla_KPC, bla_NDM and bla_OXA-48 genes. PFGE analysis showed 88 pulsotypes. Fifteen isolates were clonally unrelated. One hundred fifty-seven (91.2%) of the isolates were involved in 14 different clusters.

CONCLUSIONS

Colistin is still the most effective antibiotic for A. baumannii infections. The gene bla_OXA-23 has become the most prevalent carbapenemase in Turkey. The distribution of invasive A. baumannii isolates from different regions of Turkey is not diverse so, infection control measures at medical centers should be revised to decrease the MDR A. baumannii infections across the country. The results of this study are expected to provide an important baseline to assess the future prophylactic and therapeutic options.