Optimization of periodic treatment strategies for bacterial biofilms using an agent-based in silico approach

Biofilms are responsible for most chronic infections and are highly resistant to antibiotic treatments. Previous studies have demonstrated that periodic dosing of antibiotics can help sensitize persistent subpopulations and reduce the overall dosage required for treatment. Because the dynamics and mechanisms of biofilm growth and the formation of persister cells are diverse and are affected by environmental conditions, it remains a challenge to design optimal periodic dosing regimens. Here, we develop a computational agent-based model to streamline this process and determine key parameters for effective treatment. We used our model to test a broad range of persistence switching dynamics and found that if periodic antibiotic dosing was tuned to biofilm dynamics, the dose required for effective treatment could be reduced by nearly 77%. The biofilm architecture and its response to antibiotics were found to depend on the dynamics of persister cells. Despite some differences in the response of biofilm governed by different persister switching rates, we found that a general optimized periodic treatment was still effective in significantly reducing the required antibiotic dose. As persistence becomes better quantified and understood, our model has the potential to act as a foundation for more effective strategies to target bacterial infections.

Efficacy of prophylactic antibiotics for preterm premature rupture of membranes: a systematic review and network meta-analysis

OBJECTIVE

Various prophylactic antibiotic regimens are used in the management of preterm premature rupture of membranes. We investigated the efficacy and safety of these regimens in terms of maternal and neonatal outcomes.

DATA SOURCES

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials from inception to July 20, 2021.

STUDY ELIGIBILITY CRITERIA

We included randomized controlled trials involving pregnant women with preterm premature rupture of membranes before 37 weeks of gestation and a comparison of ≥2 of the following 10 antibiotic regimens: control/placebo, erythromycin, clindamycin, clindamycin plus gentamicin, penicillins, cephalosporins, co-amoxiclav, co-amoxiclav plus erythromycin, aminopenicillins plus macrolides, and cephalosporins plus macrolides.

METHODS

Two investigators independently extracted published data and assessed the risk of bias with a standard procedure following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Network meta-analysis was conducted using the random-effects model.

RESULTS

A total of 23 studies that recruited a total of 7671 pregnant women were included. Only penicillins (odds ratio, 0.46; 95% confidence interval, 0.27-0.77) had significantly superior effectiveness for maternal chorioamnionitis. Clindamycin plus gentamicin reduced the risk of clinical chorioamnionitis, with borderline significance (odds ratio, 0.16; 95% confidence interval, 0.03-1.00). By contrast, clindamycin alone increased the risk of maternal infection. For cesarean delivery, no significant differences were noted among these regimens.

CONCLUSION

Penicillins remain the recommended antibiotic regimen for reducing maternal clinical chorioamnionitis. The alternative regimen includes clindamycin plus gentamicin. Clindamycin should not be used alone.

Single versus dual antibiotic regimen in women with term prolonged rupture of membranes and intrapartum fever: a retrospective study

OBJECTIVES

The impact of E. coli in causing peripartum infections has been increasing due to rising ampicillin resistance. In this study, we compared maternal and neonatal outcomes of women with prolonged rupture of membranes (ROM >18h) and intrapartum fever, according to two antibiotic regimens they received, and describe the bacterial distribution focusing on risk factors for Enterobacteriaceae-related infectious morbidity.

STUDY DESIGN

This 10-year retrospective study of women with ROM >18h and intrapartum fever included 62 women who were treated with ampicillin and gentamicin due to suspected intraamniotic infection and 79 without these signs who were treated with ampicillin alone. The primary outcomes were endometritis and neonatal early-onset sepsis (EOS) rates. Outcomes were compared using univariate and multivariate analyses.

RESULTS

Among women who received ampicillin alone compared with dual therapy, rates were higher of endometritis (17% vs. 3%, p<0.001), neonatal early onset sepsis (7.5% vs. 0%, p=0.03), Enterobacteriaceae positive placental swab culture (67.9% vs. 15.7%, p<0.001), and histopathological subchorionitis (25.3% vs. 8.0%, p=0.008). Over 83% of Enterobacteriaceae isolates were ampicillin-resistant. Gestational age at delivery >41 weeks, meconium at delivery, ROM >24h and treatment with a single antibiotic agent were associated with the presence of a positive Enterobacteriaceae placental swab culture.

CONCLUSION

Ampicillin compared to dual treatment in women with prolonged ROM and fever might promote the growth of ampicillin-resistant Enterobacteriaceae (including E.coli) and increase risks of maternal and neonatal infectious morbidity.

Application of metagenomic next-generation sequencing in patients with infective endocarditis

Objectives

Metagenomic next-generation sequencing (mNGS) technology is helpful for the early diagnosis of infective endocarditis, especially culture-negative infective endocarditis, which may guide clinical treatment. The purpose of this study was to compare the presence of culture-negative infective endocarditis pathogens versus culture-positive ones, and whether mNGS test results could influence treatment regimens for patients with routine culture-negative infective endocarditis.

Methods

The present study enrolled patients diagnosed with infective endocarditis and tested for mNGS in the First Affiliated Hospital of Zhengzhou University from February 2019 to February 2022 continuously. According to the culture results, patients were divided into culture-negative group (Group CN, n=18) and culture-positive group (Group CP, n=32). The baseline characteristics, clinical data, pathogens, 30 day mortality and treatment regimen of 50 patients with infective endocarditis were recorded and analyzed.

Results

Except for higher levels of PCT in the Group CN [0.33 (0.16-2.74) ng/ml vs. 0.23 (0.12-0.49) ng/ml, P=0.042], there were no significant differences in the basic clinical data and laboratory examinations between the two groups (all P>0.05). The aortic valve and mitral valve were the most involved valves in patients with infective endocarditis (aortic valve involved: Group CN 10, Group CP 16; mitral valve involved: Group CN 8, Group CP 21; P>0.05) while 9 patients had multiple valves involved (Group CN 2, Group CP 7; P>0.05). The detection rate of non-streptococci infections in the Group CN was significantly higher than that in the Group CP (9/18 vs. 3/32, P=0.004). There was no significant difference in patients with heart failure hospitalization and all-cause death at 30 days after discharge (3 in Group CN vs. 4 in Group CP, P>0.05). It is worth noting that 10 patients with culture-negative infective endocarditis had their antibiotic regimen optimized after the blood mNGS.

Conclusions

Culture-negative infective endocarditis should be tested for mNGS for early diagnosis and to guide clinical antibiotic regimen.

Evaluation of the Therapeutic Outcomes of Antibiotic Regimen Against Carbapenemase-Producing Klebsiella pneumoniae: A Systematic Review and Meta-Analysis

Background: Carbapenemase-producing Klebsiella pneumoniae (CpKP) has been implicated as an increasing threat to public health. CpKP is a ubiquitous, opportunistic pathogen that causes both hospital and community acquired infections. This organism hydrolyzes carbapenems and other β-lactams and thus, leading to multiple resistance to these antibiotics. Despite the difficult to treat nature of infections caused by CpKP, little has been discussed on the mortality, clinical response and microbiological success rates associated with various antibiotic regimen against CpKP. This meta-analysis was designed to fill the paucity of information on the clinical impact of various antibiotic therapeutic regimens among patients infected with CpKP.

Materials and Methods: Literature in most English databases such as Medline through PubMed, Google Scholar, Web of Science, Cochrane Library and EMBASE, were searched for most studies published between the years 2015–2020. Data were analyzed using the R studio 2.15.2 statistical software program (metaphor and meta Package, Version 2) by random-effects (DerSimonian and Laird) model.

Results: Twenty-one (21) studies including 2841 patients who had been infected with CpKP were analysed. The overall mortality rate was 32.2% (95%CI = 26.23–38.87; I² = 89%; p-value ≤ 0.01, Number of patients = 2716). Pooled clinical and microbiological success rates were 67.6% (95%CI = 58.35–75.64, I² = 22%, p-value = 0.25, Number of patients = 171) and 74.9% (95%CI = 59.02–86.09, I² = 53%, p-value = 0.05, Number of patients = 121), respectively. CpKP infected patients treated with combination therapy are less likely to die as compared to those treated with monotherapy (OR = 0.55, 95%CI = 0.35–0.87, p-value = 0.01, Number of patients = 1,475). No significant difference existed between the mortality rate among 60years and above patients vs below 60years (OR = 0.84, 95%CI = 0.28–2.57, p-value = 0.76, 6 studies, Number of patients = 1,688), and among patients treated with triple therapy vs. double therapy (OR = 0.50, 95%CI = 0.21–1.22, p-value = 0.13, 2 studies, Number of patients = 102). When compared with aminoglycoside-sparing therapies, aminoglycoside-containing therapies had positive significant outcomes on both mortality and microbiological success rates.

Conclusion: New effective therapies are urgently needed to help fight infections caused by this organism. The effective use of various therapeutic options and the strict implementation of infection control measures are of utmost importance in order to prevent infections caused by CpKP. Strict national or international implementation of infection control measures and treatment guidelines will help improve healthcare, and equip governments and communities to respond to and prevent the spread of infectious diseases caused by CpKP.

A Pilot Study of Antibiotic Regimens for Infections Caused by Acinetobacter baumannii in a Secondary Hospital in Thailand

Purpose

This retrospective pilot study aimed to investigate the antibiotic regimens used to treat Acinetobacter baumannii infections at a secondary hospital in southern Thailand. Additionally, the clinical outcomes and mortality of each regimen are described.

Patients and Methods

The medical charts of all patients admitted to Phang-Nga Hospital, Thailand, between 1 January 2019 and 31 May 2020 due to Acinetobacter baumannii infection were reviewed. Data were collected on the antibiotics that patients received before and after sensitivity testing, along with the clinical cure, mortality rates, and nephrotoxicity.

Results

Of the 32 inpatients recruited in the study, the most prescribed antibiotic regimen for empirical therapy was beta-lactam/beta-lactamase inhibitor monotherapy (22%), and for definitive therapy was meropenem monotherapy (28%). Combination therapy with two, three, or four antibiotics was prescribed less than 50% of cases for both empirical and definitive therapy. Moreover, the results indicated that patients receiving combination therapy had a lower clinical response and higher mortality than those receiving monotherapy. Furthermore, regimens containing colistin did not provide a higher clinical cure compared to those without colistin.

Conclusion

The results of this pilot study support the use of monotherapy antibiotic regimens, including ceftazidime and meropenem, for the treatment of Acinetobacter baumannii infections in secondary hospitals. However, as these results are from a single hospital with limited number of patients, the application of the results should be done carefully. More patient data from other hospitals will be collected in the next phase of this study.

Pandrug-resistant Acinetobacter Baumannii Infection Identified in a Non-intensive Care Unit Patient: A Case Study

Acinetobacter baumannii is a major cause of hospital-acquired infections, particularly in patients treated in intensive care units (ICUs). It can be a causal agent of conditions like pneumonia, bacteremia, meningitis, soft-tissue, and urinary tract infections, and is associated with high mortality rates. We present a case of a 72-year-old male patient treated for fractured neck of femur who went on to develop an infection from a pandrug-resistant Acinetobacter baumannii isolated in blood and urine cultures during his hospitalization in trauma and orthopedic ward. The patient was operated on the second day following his injury with a cephalomedullary nail device and became febrile with rigors on day six. His clinical condition deteriorated over the next days and his inflammatory markers reached a peak value on day 10 post-injury. Acinetobacter baumannii was isolated from blood and urine cultures and a regimen combining rifampicin, tigecycline, and vancomycin in their maximum doses was initiated. The patient was discharged on day 26 post-injury. Before discharge, he had received the above-mentioned intravenous antibiotic regimen for 14 days. He had also been afebrile for six days and undergone three consecutive negative blood culture samples.

Intraperitoneal Cefepime Monotherapy Versus Combination Therapy of Cefazolin Plus Ceftazidime for Empirical Treatment of CAPD-Associated Peritonitis: A Multicenter, Open-Label, Noninferiority, Randomized, Controlled Trial

RATIONALE & OBJECTIVE

Compared to combination therapy, intraperitoneal (IP) cefepime monotherapy for continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis may provide potential benefits in lowering staff burden, shortening time-consuming antibiotic preparation, and reducing bag contamination risk. This study sought to evaluate whether cefepime monotherapy is noninferior to combination regimens.

STUDY DESIGN

Multicenter, open-label, noninferiority, randomized, controlled trial.

SETTING & PARTICIPANTS

Adult incident peritoneal dialysis (PD) patients with CAPD-associated peritonitis in 8 PD centers in Thailand.

INTERVENTIONS

Random assignment to either IP monotherapy of cefepime, 1g/d, or IP combination of cefazolin and ceftazidime, 1g/d, both given as continuous dosing.

OUTCOMES

Primary end point: resolution of peritonitis at day 10 (primary treatment response).

SECONDARY OUTCOMES

initial response (day 5), complete cure (relapse/recurrence-free response 28 days after treatment completion), relapsing/recurrent peritonitis, and death from any cause. Noninferiority would be confirmed for the primary outcome if the lower margin of the 1-sided 95% CI was not less than-10% for difference in the primary response rate. A 2-sided 90% CI was used to demonstrate the upper or lower border of the 1-sided 95% CI.

RESULTS

There were 144 eligible patients with CAPD-associated peritonitis, of whom 70 and 74 patients were in the monotherapy and combination-therapy groups, respectively. Baseline demographic and clinical characteristics were not different between the groups. The primary response was 82.6% in the monotherapy group and 81.1% in the combination-therapy group (treatment difference, 1.5%; 90% CI, -9.1% to 12.1%; P=0.04). There was no significant difference in the monotherapy group compared with the combination-therapy group in terms of initial response rate (65.7% vs 60.8%; treatment difference, 4.9%; 95% CI, -10.8% to 20.6%; P=0.5) and complete cure rate (80.0% vs 80.6%; treatment difference, -0.6%; 95% CI, -13.9% to 12.8%; P=0.7). Relapsing and recurrent peritonitis occurred in 4.6% and 4.6% of the monotherapy group and 4.2% and 5.6% of the combination-therapy group (P=0.9and P=0.8, respectively). There was nominally higher all-cause mortality in the monotherapy group (7.1% vs 2.7%; treatment difference, 4.4%; 95% CI, -2.6% to 11.5%), but this difference was not statistically significant (P = 0.2).

LIMITATION

Not double blind.

CONCLUSIONS

IP cefepime monotherapy was noninferior to conventional combination therapy for resolution of CAPD-associated peritonitis at day 10 and may be a reasonable alternative first-line treatment.

FUNDING

This study is supported by The Kidney Foundation of Thailand (R5879), Thailand; Rachadaphiseksompotch Fund (RA56/006) and Rachadaphicseksompotch Endorsement Fund (CU-GRS_61_06_30_01), Chulalongkorn University, Thailand; National Research Council of Thailand (156/2560), Thailand; and Thailand Research Foundation (IRG5780017), Thailand.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT02872038.

An update on the pharmacotherapeutic management of lower respiratory tract infections

INTRODUCTION

Our knowledge about lower respiratory tract infections (LRTIs) has improved substantially in the last years, but the management of respiratory infections is still a challenge and we are still far from using precision medicine in their treatment. Areas covered: The approaches developed in recent years to improve the pharmacotherapeutic management of LRTIs, such as novel diagnostic assays to facilitate medical decision-making, attempts for selecting an optimal empiric antibiotic regimen, and the role of new and possibly unproven adjunctive therapies, are described. Expert opinion: Early and appropriate antibiotics remain the cornerstone in the treatment of LRTIs. The updated trend is to apply antimicrobial stewardship principles and initiatives to optimize both the management and the outcomes of LTRIs. Biomarkers, mainly C-reactive protein (CRP) and procalcitonin (PCT), can improve the diagnostic and prognostic assessment of LRTIs and aid to guide antibiotic therapy. The widespread use of antimicrobial agents has greatly contributed to faster development of antibiotic resistance and the emergence of opportunistic pathogens, which substitute the indigenous microbiota. However, very few new antibiotics in development to overcome existing resistance and ensure continued success in the treatment of LRTIs have been approved, likely because antibiotic stewardship programs discourage the use of new agents.

CIED infection with either pocket or systemic infection presentation--complete device removal and long-term antibiotic treatment; long-term outcome

OBJECTIVE

Cardiovascular implantable electronic device (CIED) infections are increasing in numbers. The objective was to review the clinical presentation and outcome in patients affected with CIED infections with either local pocket or systemic presentation.

DESIGN

All device removals due to CIED infection during the period from 2005 to 2012 were retrospectively reviewed. CIED infections were categorized as systemic or pocket infections. Treatment included complete removal of the device, followed by antibiotic treatment of six weeks.

RESULTS

Seventy-one device removals due to infection (32 systemic and 39 pocket infections) were recorded during the study period. Median follow-up time was 26 (IQR 9-41) months, 30 day and 12 month mortality were 4% and 14%, respectively. There was no long-term difference in mortality between patients with pocket vs. systemic infection (p = 0.48). During follow-up no relapses and two cases of new infections were noted (2.8%).

CONCLUSIONS

CIED infection with systemic or pocket infection was difficult to distinguish in clinical presentation and outcome. Complete device removal and antibiotic treatment of long duration was safe and without relapses.

Single daily dosing ceftriaxone and metronidazole vs standard triple antibiotic regimen for perforated appendicitis in children: a prospective randomized trial

INTRODUCTION

Appendicitis is the most common emergency condition in children. Historically, a 3-drug regimen consisting of ampicillin, gentamicin, and clindamycin (AGC) has been used postoperatively for perforated appendicitis. A retrospective review at our institution has found single day dosing of ceftriaxone and metronidazole (CM) to be a more simple and cost-effective antibiotic strategy. Therefore, we performed a prospective, randomized trial to compare efficacy and cost-effectiveness of these 2 regimens.

METHODS

After internal review board approval (IRB no. 04 12-149), children found to have perforated appendicitis at appendectomy were randomized to either once daily dosing of CM (2 total doses per day) or standard dosing of AGC (11 total doses per day). Perforation was defined as an identifiable hole in the appendix. The operative approach (laparoscopic), length of antibiotic use, and criteria for discharge were standardized for the groups. Based on our retrospective analysis using length of postoperative hospitalization as a primary end point, a sample size of 100 patients was calculated for an alpha of .5 and a power of 0.82.

RESULTS

One hundred patients underwent laparoscopic appendectomy for perforated appendicitis. On presentation, there were no differences in sex distribution, days of symptoms, temperature, or leukocyte count. There was no difference in abscess rate or wound infections between groups. The CM group resulted in significantly less antibiotic charges then the AGC group.

CONCLUSIONS

Once daily dosing with the 2-drug regimen (CM) offers a more efficient, cost-effective antibiotic management in children with perforated appendicitis without compromising infection control when compared to a traditional 3-drug regimen.