Clinical Culture Surveillance of Carbapenem-Resistant Pseudomonas aeruginosa and Acinetobacter Species in a Teaching Hospital in São Paulo, Brazil: A 7-Year Study

Immediate and later impacts of antimicrobial consumption on carbapenem-resistant Acinetobacter spp., Pseudomonas aeruginosa, and Klebsiella spp. in a teaching hospital in Brazil: a 10-year trend study

To evaluate trends and the immediate and late impact of antimicrobial consumption on carbapenem-resistant Acinetobacter spp. (CRAs), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and carbapenem-resistant Klebsiella spp. (CRKs) over a 10-year period. An ecological study was conducted at the teaching hospital in São Paulo, Brazil, from 2007 to 2016. Consumption and resistance data were collected from the supply sector and central laboratory of the institution, respectively. Associations between consumption and resistance were analyzed in the same year, 1 year later, and 2 years later by linear regression of mixed effects. A total of 22,041 isolates were analyzed. Among these, 9988 corresponded to the gram-negatives in this study [3682 (36.9%) were Klebsiella spp., 3169 (31.7%) were P. aeruginosa, and 3137 (31.4%) were Acinetobacter spp.]. An increasing trend of consumption was observed, except for fourth-generation cephalosporins. Carbapenems were the most used antimicrobial class; CRKs presented a substantial increase over this period (from 1.4 to 67.0%; p = 0.001). Increased consumption of third-generation cephalosporins reduced CRAs [- 2.43%, 95% confidence interval (CI), - 3.30 to - 1.57; p < 0.001] and increased CRPA [26.67%, 95% CI, 2.99 to 50.35; p = 0.034] in the same year. Increased consumption of β-lactam/β-lactamase inhibitors increased CRKs with a 1-year delay [5.13%, 95% CI, 2.40 to 7.86; p = 0.001]. Our study demonstrated high antimicrobial consumption and growing carbapenem-resistance rates among gram-negative bacteria, especially Klebsiella spp., and the immediate and later effects of consumption of multiple antimicrobials on carbapenem resistance.

Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

The non-glucose-fermenting Gram-negative bacilli Pseudomonas aeruginosa and Acinetobacter baumannii are increasingly acquiring carbapenem resistance. Given their intrinsic antibiotic resistance, this can cause extremely difficult-to-treat infections. Additionally, resistance gene transfer can occur between Gram-negative species, regardless of their ability to ferment glucose. Thus, the acquisition of carbapenemase genes by these organisms increases the risk of carbapenemase spread in general. Ultimately, infection control practitioners and clinical microbiologists need to work together to determine the risk carried by carbapenem-resistant non-glucose-fermenting Gram-negative bacilli (CR-NF) in their institution and what methods should be considered for surveillance and detection of CR-NF.

Phenotypic detection of metallo-β-lactamases in Pseudomonas aeruginosa and Acinetobacter baumannii isolated from hospitalized patients in São Luis, State of Maranhão, Brazil

INTRODUCTION

Acquired metallo-β-lactamases (MβL) are emerging determinants of resistance in Pseudomonas aeruginosa and Acinetobacter baumannii. The objectives of this study were to phenotypically detect MβL in imipenem-resistant P. aeruginosa and A. baumannii, to investigate the association between MβL-positive strains and hospitals, and to compare the resistance profiles of MβL-producing and non-MβL-producing strains.

METHODS

The approximation disk and combined disk assay methods were used in this study.

RESULTS

A total of 18 (38.3%) P. aeruginosa isolates and 1 (5.6%) A. baumannii isolate tested positive for the presence of MβL.

CONCLUSIONS

These results demonstrate the need for strict surveillance and for the adoption of preventive measures to reduce the spread of infection and potential outbreaks of disease caused by MβL-producing microorganisms.

Prevalence and clinical outcomes of episodes of ventilator-associated pneumonia caused by SPM-1-producing and non-producing imipenem-resistant Pseudomonas aeruginosa

INTRODUCTION

Pseudomonas aeruginosa is a leading cause of ventilator-associated pneumonia (VAP) and exhibits high rates of resistance to several antimicrobial drugs. The carbapenens are usually the drugs of choice against this microorganism. However, the carbapenem resistance has increased among these strains worldwide. The presence of metallo-β-lactamases (MBL) has been pointed out as a major mechanism of resistance among these strains. No previous study addressed outcomes of respiratory infections caused by these strains.

METHODS

Our group sought to analyze the epidemiology and clinical outcomes of patients with VAP caused by imipenem-resistant P. aeruginosa. A total of 29 clinical isolates of carbapenem-resistant Pseudomonas aeruginosa were screened for metallo-β-lactamase (MBL) genes.

RESULTS

Demographic and clinical variables were similar between the SPM-1-producing and non-SPM-1-producing group. Five (17.2%) isolates were positive for blaSPM-1. No other MBL gene was found. All patients were treated with polymyxin B. The infection-related mortality was 40% and 54.2% for SPM-1-producing and -non-producing isolates, respectively.

CONCLUSIONS

There were no differences in epidemiological and clinical outcomes between the two groups.

Metallo-β-lactamase and genetic diversity of Pseudomonas aeruginosa in intensive care units in Campo Grande, MS, Brazil

Infection by Pseudomonas aeruginosa has spread worldwide, with limited options for treatment. The purpose of this study was to investigate metallo-β-lactamase-producing P. aeruginosa strains and compare their genetic profile using samples collected from patients in intensive care units. Forty P. aeruginosa strains were isolated from two public hospitals in Campo Grande, Mato Grosso do Sul State, from January 1st, 2007 to June 31st, 2008. Profiles of antimicrobial susceptibility were determined using the agar diffusion method. Metallo-β-lactamase was investigated using the double-disk diffusion test and PCR. Molecular typing was performed by pulsed-field gel electrophoresis (PFGE). Respiratory and urinary tracts were the most common isolation sites. Of the 40 samples tested, 72.5% (29/40) were resistant to ceftazidime and 92.5% (37/40) to imipenem, whereas 65% (26/40) were resistant to both antimicrobials. Fifteen pan-resistant samples were found. Five percent (2/40) of samples were positive for metallo-β-lactamase on the phenotype test. No metallo-β-lactamase subtype was detected by PCR. Macrorestriction analysis revealed 14 distinct genetic patterns. Based on the superior accuracy of PCR, it can be inferred that P. aeruginosa isolates from the investigated hospitals have alternative mechanisms of carbapenem resistance. The results also suggest clonal spread of P. aeruginosa between the studied hospitals.

Risk factors for hospital-acquired pneumonia caused by imipenem-resistant Pseudomonas aeruginosa in an intensive care unit

Imipenem-resistant Pseudomonas aeruginosa is a leading cause of hospital-acquired pneumonia. Aiming to determine the risk factors associated for hospital-acquired pneumonia due to imipenem-resistant Pseudomonas aeruginosa, we undertook a retrospective case-case-control study. Patients admitted to a 14-bed medical-surgical intensive care unit from a university-affiliated hospital with hospital-acquired pneumonia caused by imipenem-resistant Pseudomonas aeruginosa strains and by imipenem-susceptible Pseudomonas aeruginosa strains were matched to control patients by time under risk and comorbidities. A total of 58 resistant cases, 47 susceptible cases and 237 controls were evaluated. The risk factors independently associated to hospital-acquired pneumonia caused by imipenem-resistant Pseudomonas aeruginosa were: duration of hospitalisation, Acute Physiological and Chronic Health Evaluation II score, male gender receipt of haemodialysis, receipt of piperacillin-tazobactam and receipt of third-generation cephalosporins.

Management of antibiotic resistance in the intensive care unit setting

Over the past few decades, an alarming increase of infections caused by antibiotic-resistant pathogens, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus species, carbapenem-resistant Pseudomonas aeruginosa, extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella spp., and multidrug-resistant Acinetobacter spp., has been observed, particularly in intensive care units. For clinicians, the rising resistance rate observed in nosocomial pathogens, when coupled with the lack of effective antimicrobials, represents the real challenge in the therapeutic management of critically ill patients. The contribution of clinicians in minimizing the increasing trend of resistance is represented by reduction of the patients' exposure to antibiotics, which reduces the resistance-selecting pressure, and by avoiding unnecessary antibiotic treatments. Recent issues on strategies to minimize resistance development and to appropriately manage critically ill patients with infections caused by multidrug-resistant organisms in the intensive care unit setting are discussed in this article.

Imipenem-resistant Pseudomonas aeruginosa infection at a medical-surgical intensive care unit: risk factors and mortality

OBJECTIVES

The aim of this study was to evaluate the risk factors and attributable mortality associated with imipenem-resistant Pseudomonas aeruginosa (IRPA) infections in a medical-surgical intensive care unit (ICU).

METHODS

A retrospective case-control study was carried out at a 16-bed medical-surgical ICU in a 780-bed, university-affiliated hospital. All patients admitted from January 1, 2003, to December 31, 2004, who had nosocomial infection caused by IRPA, were included in the study.

RESULTS

Imipenem-resistant P. aeruginosa was recovered from 63 patients during the study period. One hundred eighty-two controls were matched with cases by period of admission, age, and time at risk. Urinary tract (34.9%) and respiratory tract (22.2%) were the main sources of IRPA isolation. In multivariate analysis, a previous stay in the ICU (odds ratio, 3.54; 95% confidence interval [CI], 1.29-9.73; P = .03) was the only independent risk factor for IRPA infection. The in-hospital mortality rate among case patients was 49% (31 of 63) compared with 33% (61 of 182) for control patients (odds ratio, 1.92; 95% CI, 1.07-3.44; P = .02). Thus, we had an attributable mortality of 16% (95% CI, 9.74%-22.3%; P = .03).

CONCLUSIONS

Our study suggests that IRPA infections are strongly related to previous ICU stay, and that IRPA infections significantly increase mortality in those critical patients.

Intravenous polymyxin B for the treatment of nosocomial pneumonia caused by multidrug-resistant Pseudomonas aeruginosa

Nosocomial pneumonia caused by multidrug-resistant (MDR) Pseudomonas aeruginosa is becoming increasingly prevalent throughout the world. The use of polymyxins to treat these infections has greatly increased. We analysed 74 patients with nosocomial pneumonia caused by MDR P. aeruginosa who were treated with polymyxin B. A favourable outcome was observed in 35 patients (47.3%). A case-control study was performed to assess the variables associated with an unfavourable outcome. The presence of acute respiratory distress syndrome (odds ratio (OR)=11.29, 95% confidence interval (CI) 2.64-48.22; P=0.001) and septic shock (OR=4.81, 95% CI 1.42-16.25; P=0.01) were independently associated with an unfavourable outcome in patients with nosocomial pneumonia due to MDR P. aeruginosa. Our study demonstrated that polymyxin B is a reliable antimicrobial drug, but only as salvage therapy, for nosocomial pneumonia caused by MDR P. aeruginosa.