Clinical Predictors of Pseudomonas aeruginosa Bacteremia in Emergency Department

Zinc sulfate acts as an efflux pump inhibitor on Pseudomonas aeruginosa clinical isolates

Efflux pumps in Pseudomonas aeruginosa play an important role in decreasing the bacterium's antibiotic susceptibility. This study aimed to identify P. aeruginosa efflux pumps and examine the effect of Zinc sulfate on these pumps. This study was conducted on 104 P. aeruginosa clinical isolates collected from different types of specimens. The antimicrobial susceptibility pattern of all isolates was examined by disc diffusion and microdilution methods. A Cartwheel test was done for phenotypic detection of P. aeruginosa efflux pumps in the presence and absence of zinc sulfate. The expression of efflux pumps encoding genes and their regulators in the presence and absence of zinc sulfate was measured using real-time reverse transcriptase PCR. A high rate of multidrug-resistant (MDR) pattern was observed among the tested isolates (55.7%). Combining different antibiotics with Zinc sulfate exhibited synergistic effects against most of the studied isolates. The addition of sub-inhibitory concentrations of Zinc sulfate to the cartwheel test was found to inhibit efflux pump activity in all tested isolates. The expression of the positive regulator gene, mexT, was significantly decreased. Additionally, Zinc sulfate significantly upregulated the expression of the mexR gene (P-value < 0.05), a negative regulator of the MexAB-OprM efflux pump. Zinc sulfate demonstrated a strong antimicrobial effect against P. aeruginosa clinical isolates. We recommend the use of Zinc sulfate as an antibiotic adjuvant and efflux pump inhibitor in the treatment of P. aeruginosa infections to enhance the bacterium's susceptibility to antimicrobial agents.

Relationship between Target Time above Minimum Inhibitory Concentration Achievement Rate of Meropenem Using Monte Carlo Simulation and In-Hospital Survival in Patients with Pseudomonas aeruginosa Bacteremia

Pseudomonas aeruginosa bacteremia is associated with a high mortality rate, and meropenem (MEPM) is commonly used to treat it. However, the relationship between the time above the minimum inhibitory concentration (fT>MIC) of MEPM and its therapeutic efficacy in P. aeruginosa bacteremia has not been explored. This study aimed to investigate this relationship by defining the target % fT>MIC of MEPM as 75%. The retrospective study spanned 14 years and included hospitalized patients treated with MEPM for P. aeruginosa bacteremia. Monte Carlo simulation was used to calculate the probability of target attainment (PTA) for each patient, and the threshold for a PTA of 75% fT>MIC associated with in-hospital survival was determined using receiver operating characteristic (ROC) curves. The ROC curve-derived PTA associated with improved in-hospital survival was 65.0%, a significant finding in multivariate logistic regression analysis adjusted for patient background factors (odds ratio: 20.49, 95% confidence interval: 3.02-245.23, p = 0.005). This result suggests a dosing regimen that achieves a PTA of at least 65% when the target fT>MIC of MEPM for treating P. aeruginosa bacteremia is defined as 75%.

Comparison of Length of Hospital Stay for Community-Acquired Infections Due to Enteric Pathogens, Influenza Viruses and Multidrug-Resistant Bacteria: A Cross-Sectional Study in Hungary

Community-acquired infections (CAI) can affect the duration of care and mortality of patients. Therefore, we aimed to investigate these as well as factors influencing the length of hospital stay in patients with CAI due to enteric pathogens, influenza viruses and multidrug-resistant (MDR) bacteria. We obtained data on 531 patients with CAI from the medical databases of a Hungarian university hospital and analyzed their characteristics using a regression model. Patients with MDR bacterial infection had the highest mortality (26.24%) and they stayed significantly longer in the hospital than cases with other CAIs. Our results showed that infection by Clostridioides difficile (odds ratio (OR): 6.98, 95% confidence interval (CI): 1.03-47.48; p = 0.047), MDR Escherichia coli (OR: 7.64, 95% CI: 1.24-47.17; p = 0.029), MDR Klebsiella spp. (OR: 7.35, 95% CI: 1.15-47.07; p = 0.035) and hospitalization in the department of pulmonology (OR: 5.48, 95% CI: 1.38-21.76; p = 0.016) and surgery (OR: 4.19, 95% CI: 1.18-14.81; p = 0.026) significantly increased, whereas female sex (OR: 0.62, 95% CI: 0.40-0.97; p = 0.037) and hospitalization in the department of pediatrics (OR: 0.17, 95% CI: 0.04-0.64; p = 0.009) decreased the odds of staying in the hospital for more than 6 days. Our findings provide new information on the epidemiology of CAI and can contribute to the development of public health programs that decrease the burden of infections acquired in the community.

Routine laboratory biomarkers used to predict Gram-positive or Gram-negative bacteria involved in bloodstream infections

This study evaluated routine laboratory biomarkers (RLB) to predict the infectious bacterial group, Gram-positive (GP) or Gram-negative (GN) associated with bloodstream infection (BSI) before the result of blood culture (BC). A total of 13,574 BC of 6787 patients (217 BSI-GP and 238 BSI-GN) and 68 different RLB from these were analyzed. The logistic regression model was built considering BSI-GP or BSI-GN as response variable and RLB as covariates. After four filters applied total of 320 patients and 16 RLB remained in the Complete-Model-CM, and 4 RLB in the Reduced-Model-RM (RLB p > 0.05 excluded). In the RM, only platelets, creatinine, mean corpuscular hemoglobin and erythrocytes were used. The reproductivity of both models were applied to a test bank of 2019. The new model presented values to predict BSI-GN of the area under the curve (AUC) of 0.72 and 0.69 for CM and RM, respectively; with sensitivity of 0.62 and 0.61 (CM and RM) and specificity of 0.67 for both. These data confirm the discriminatory capacity of the new models for BSI-GN (p = 0.64). AUC of 0.69 using only 4 RLB, associated with the patient's clinical data could be useful for better targeted antimicrobial therapy in BSI.

Duration of Treatment for Pseudomonas aeruginosa Bacteremia: a Retrospective Study

INTRODUCTION

There is no consensus regarding optimal duration of antibiotic therapy for Pseudomonas aeruginosa bacteremia. We aimed to evaluate the impact of short antibiotic course.

METHODS

We present a retrospective multicenter study including patients with P. aeruginosa bacteremia during 2009-2015. We evaluated outcomes of patients treated with short (6-10 days) versus long (11-15 days) antibiotic courses. The primary outcome was a composite of 30-day mortality or bacteremia recurrence and/or persistence. Univariate and inverse probability treatment-weighted (IPTW) adjusted multivariate analysis for the primary outcome was performed. To avoid immortal time bias, the landmark method was used.

RESULTS

We included 657 patients; 273 received a short antibiotic course and 384 a long course. There was no significant difference in baseline characteristics of patients. The composite primary outcome occurred in 61/384 patients in the long-treatment group (16%) versus 32/273 in the short-treatment group (12%) (p = 0.131). Mortality accounted for 41/384 (11%) versus 25/273 (9%) of cases, respectively. Length of hospital stay was significantly shorter in the short group [median 13 days, interquartile range (IQR) 9-21 days, versus median 15 days, IQR 11-26 days, p = 0.002]. Ten patients in the long group discontinued antibiotic therapy owing to adverse events, compared with none in the short group. On univariate and multivariate analyses, duration of therapy was not associated with the primary outcome.

CONCLUSIONS

In this retrospective study, 6-10 days of antibiotic course for P. aeruginosa bacteremia were as effective as longer courses in terms of survival and recurrence. Shorter therapy was associated with reduced length of stay and less drug discontinuation.

β-lactam Resistance in Pseudomonas aeruginosa: Current Status, Future Prospects

Pseudomonas aeruginosa is a major opportunistic pathogen, causing a wide range of acute and chronic infections. β-lactam antibiotics including penicillins, carbapenems, monobactams, and cephalosporins play a key role in the treatment of P. aeruginosa infections. However, a significant number of isolates of these bacteria are resistant to β-lactams, complicating treatment of infections and leading to worse outcomes for patients. In this review, we summarize studies demonstrating the health and economic impacts associated with β-lactam-resistant P. aeruginosa. We then describe how β-lactams bind to and inhibit P. aeruginosa penicillin-binding proteins that are required for synthesis and remodelling of peptidoglycan. Resistance to β-lactams is multifactorial and can involve changes to a key target protein, penicillin-binding protein 3, that is essential for cell division; reduced uptake or increased efflux of β-lactams; degradation of β-lactam antibiotics by increased expression or altered substrate specificity of an AmpC β-lactamase, or by the acquisition of β-lactamases through horizontal gene transfer; and changes to biofilm formation and metabolism. The current understanding of these mechanisms is discussed. Lastly, important knowledge gaps are identified, and possible strategies for enhancing the effectiveness of β-lactam antibiotics in treating P. aeruginosa infections are considered.

Risk factors, antimicrobial susceptibility pattern and patient outcomes of Pseudomonas aeruginosa infection: A matched case-control study

BACKGROUND

Pseudomonas aeruginosa is a leading nosocomial Gram-negative bacteria associated with prolonged hospitalization, and increased morbidity and mortality. Limited data exist regarding P. aeruginosa infection and outcome in patients managed in intensive care units (ICUs) in the Gulf countries. We aimed to determine the risk factors, antimicrobial susceptibility pattern and patient outcomes of P. aeruginosa infection in ICU.

METHODS

In this matched case-control study, all P. aeruginosa infections that occurred >48 h after hospital admission between January 31st 2016 and December 31st 2018 at ICUs affiliated with King Abdulaziz Medical City, Riyadh were included. P. aeruginosa was identified using MALDI-TOF (Vitek-MS) by biomérieux, and the antimicrobial susceptibility testing was performed using an automated biomérieux VITEK^®️ 2 Antimicrobial Susceptibility card.

RESULTS

The study included 90 cases and 90 controls. Compared with controls, cases had significantly higher mean ICU stay and higher proportions with previous history of antimicrobial therapy, coronary artery disease, malignancy, hemodialysis, previous surgery, use of central line, urethral catheterization, nasogastric tube, and tracheostomy. In a multivariate conditional logistic regression analysis, factors independently associated with P. aeruginosa infection were ICU duration [Odds Ratio (OR) 9.05, 95%CI 2.53-32.27, p = .001], previous surgery (OR = 7.33, 95%CI 1.66-32.36, p = .009), tracheostomy (OR = 11.13, 95%CI 1.05-118.59, p = .046), urethral catheterization (OR = 7.38, 95%CI 1.21-45.11, p = .030) and use of aminoglycosides (OR = 10.59, 95%CI 1.14-98.13, p = .038). Approximately 41% of P. aeruginosa isolates were resistant to imipenem, while 36.7% were multidrug-resistant. Mortality was similar in both groups: 54(60%) cases and 51(56.7%) controls; p = .650.

CONCLUSIONS

The study identifies several potentially modifiable factors associated with P. aeruginosa infection in ICUs. Identification of these factors could facilitate case identification and enhance control measures.