Ampicillin and penicillin concentration in serum and pleural fluid of hospitalized children with community-acquired pneumonia

Dual-Aptamer Drift Canceling Techniques to Improve Long-Term Stability of Real-Time Structure-Switching Aptasensors

This paper presents a dual-aptamer scheme to mitigate signal drifts caused by structure-switching aptamers during long-term monitoring. Electrochemical aptamer-based (E-AB) biosensors have recently shown great potential for continuous in vivo monitoring. However, the accuracy of detection is often limited by signaling drifts. Traditional approaches rely on kinetic differential measurements (KDM) coupled with square-wave voltammetry to eliminate these drifts. Yet, we have discovered that KDM does not apply universally to all aptamers, as their responses at different SWV frequencies heavily rely on their structure-switching characteristics and the electron transfer (ET) kinetics of the redox reporters. In light of this, we propose a "dual-aptamer" scheme that utilizes two aptamers, each responding differently to the same target molecule to cancel out drift. These paired aptamers are identified through (1) screening from an existing pool of aptamers and (2) engineering the signaling behavior of the redox reporters. We demonstrate the differential signaling of the aptamer pair in the presence of ampicillin and ATP molecules and show that the pair exhibits similar drifts in undiluted goat serum. By implementing drift cancelation, sensor drift is reduced by a factor of 370. Additionally, the differential signaling enables an increased recording throughput by leveraging differential readout electronics. The authors believe that the proposed technique holds significant benefits for long-term in vivo monitoring.

Lung penetration and pneumococcal target binding of antibiotics in lower respiratory tract infection

OBJECTIVES

To achieve the therapeutic effects, antibiotics must penetrate rapidly into infection sites and bind to targets. This study reviewed updated knowledge on the ability of antibiotics to penetrate into the lung, their physicochemical properties influencing the pulmonary penetration and their ability to bind to targets on pneumococci.

METHODS

A search strategy was developed using PubMED, Web of Science, and ChEMBL. Data on serum protein binding, drug concentration, target binding ability, drug transporters, lung penetration, physicochemical properties of antibiotics in low respiratory tract infection (LRTI) were collected.

RESULTS

It was seen that infection site-to-serum concentration ratios of most antibiotics are >1 at different time points except for ceftriaxone, clindamycin and vancomycin. Most agents have proper physicochemical properties that facilitate antibiotic penetration. In antimicrobial-resistant Streptococcus pneumoniae, the binding affinity of antibiotics to targets mostly decreases compared to that in susceptible strains. The data on binding affinity of linezolid, clindamycin and vancomycin were insufficient. The higher drug concentration at the infection sites compared to that in the blood can be associated with inflammation conditions. Little evidence showed the effect of drug transporters on the clinical efficacy of antibiotics against LRTI.

CONCLUSIONS

Data on antibiotic penetration into the lung in LRTI patients and binding affinity of antibiotics for pneumococcal targets are still limited. Further studies are required to clarify the associations of the lung penetration and target binding ability of antibitotics with therapeutic efficacy to help propose the right antibiotics for LRTI.

Resistance to β-lactams in Streptococcus pneumoniae

Streptococcus pneumoniae is an important causal agent of pneumonia, meningitis, sepsis, bacteremia, and otitis media. Penicillin resistance rates in S. pneumoniae have remained stable in Argentina in the last years. In the late '90s more isolates with MIC of penicillin ≥2μg/ml were observed; however, their frequency has decreased in recent years. The phenotypic expression of penicillin resistance is due to a modification in penicillin-binding proteins associated with a mosaic structure in the coding genes. The expansion of successful resistant clones varies among the different regions and is influenced by the use of antibiotics, vaccines, particularly conjugated ones, as well as population density. Parenteral treatment with high doses of penicillin G continues to be effective for the treatment of pneumonia and bacteremia, oral aminopenicillins for otitis media and sinusitis and third generation cephalosporins for meningitis.

A copper-dependent compound restores ampicillin sensitivity in multidrug-resistant Staphylococcus aureus

Multi-drug resistant Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), has become a worldwide, major health care problem. While initially restricted to clinical settings, drug resistant S. aureus is now one of the key causative agents of community-acquired infections. We have previously demonstrated that copper dependent inhibitors (CDIs), a class of antibiotics that are only active in the presence of copper ions, are effective bactericidal agents against MRSA. A second-generation CDI, APT-6K, exerted bactericidal activity at nanomolar concentrations. At sub-bactericidal concentrations, it effectively synergized with ampicillin to reverse drug resistance in multiple MRSA strains. APT-6K had a favorable therapeutic index when tested on eukaryotic cells (TI: > 30) and, unlike some previously reported CDIs, did not affect mitochondrial activity. These results further establish inhibitors that are activated by the binding of transition metal ions as a promising class of antibiotics, and for the first time, describe their ability to reverse existing drug resistance against clinically relevant antibiotics.

Hematopoiesis and the bacterial microbiome

Recent studies have revealed that the intestinal bacterial microbiome plays an important role in the regulation of hematopoiesis. A correlation between adverse hematologic effects and imbalance of the intestinal microbiome, or dysbiosis, is evident in several human conditions, such as inflammatory bowel disease, obesity, and, critically, in the setting of antibiotic exposure. Here we review the effects of gut dysbiosis on the hematological compartment and our current understanding of the mechanisms through which changes in the bacterial microbiome affect hematopoiesis.

A reagentless and reusable electrochemical aptamer-based sensor for rapid detection of ampicillin in complex samples

We report the design and fabrication of a "signal-on" electrochemical aptamer-based (E-AB) sensor for detection of ampicillin. The signaling of the sensor is based on target binding-induced changes in the conformation and flexibility of the methylene blue-modified aptamer probe. The sensor's response is fast; signal saturation can be reached in ~ 200s. Since all the sensor components are surface-immobilized, it is regenerable and can be reused for at least three times. It has demonstrated good specificity and is capable of differentiating between ampicillin and structurally similar antibiotics such as amoxicillin. More importantly, it is selective enough to be employed directly in complex samples, including serum, saliva, and milk. Although both alternating current voltammetry (ACV) and square wave voltammetry (SWV) are suitable sensor characterization techniques, our results show that ACV is better suited for target analysis. Even under the optimal experimental conditions, the limit of detection of the sensor obtained in ACV (1µM) is significantly lower than that obtained in SWV (30µM).

A Protocol for Functional Assessment of Whole-Protein Saturation Mutagenesis Libraries Utilizing High-Throughput Sequencing

Site-directed mutagenesis has long been used as a method to interrogate protein structure, function and evolution. Recent advances in massively-parallel sequencing technology have opened up the possibility of assessing the functional or fitness effects of large numbers of mutations simultaneously. Here, we present a protocol for experimentally determining the effects of all possible single amino acid mutations in a protein of interest utilizing high-throughput sequencing technology, using the 263 amino acid antibiotic resistance enzyme TEM-1 β-lactamase as an example. In this approach, a whole-protein saturation mutagenesis library is constructed by site-directed mutagenic PCR, randomizing each position individually to all possible amino acids. The library is then transformed into bacteria, and selected for the ability to confer resistance to β-lactam antibiotics. The fitness effect of each mutation is then determined by deep sequencing of the library before and after selection. Importantly, this protocol introduces methods which maximize sequencing read depth and permit the simultaneous selection of the entire mutation library, by mixing adjacent positions into groups of length accommodated by high-throughput sequencing read length and utilizing orthogonal primers to barcode each group. Representative results using this protocol are provided by assessing the fitness effects of all single amino acid mutations in TEM-1 at a clinically relevant dosage of ampicillin. The method should be easily extendable to other proteins for which a high-throughput selection assay is in place.

[Community acquired pneumonia in children: Treatment of complicated cases and risk patients. Consensus statement by the Spanish Society of Paediatric Infectious Diseases (SEIP) and the Spanish Society of Paediatric Chest Diseases (SENP)]

The incidence of community-acquired pneumonia complications has increased during the last decade. According to the records from several countries, empyema and necrotizing pneumonia became more frequent during the last few years. The optimal therapeutic approach for such conditions is still controversial. Both pharmacological management (antimicrobials and fibrinolysis), and surgical management (pleural drainage and video-assisted thoracoscopic surgery), are the subject of continuous assessment. In this paper, the Spanish Society of Paediatric Infectious Diseases and the Spanish Society of Paediatric Chest Diseases have reviewed the available evidence. Consensus treatment guidelines are proposed for complications of community-acquired pneumonia in children, focusing on parapneumonic pleural effusion. Recommendations are also provided for the increasing population of patients with underlying diseases and immunosuppression.

Retrospective analysis of the efficacies of two different regimens of aqueous penicillin G administered to children with pneumonia

Community-acquired pneumonia (CAP) is an important childhood health problem. Penicillin remains appropriate for treating children with CAP. Clinical data are lacking on disease evolution in children treated with different posologic schemes of aqueous penicillin G. To assess if there were differences in disease evolution between children with CAP treated with 6 or 4 daily doses of aqueous penicillin G, we reviewed the medical charts of hospitalized patients 2 months to 11.5 years of age. Pneumonia was radiologically confirmed based on the detection of pulmonary infiltrate or pleural effusion on the chest radiograph taken on admission and read by a pediatric radiologist blinded to the clinical data. The total daily dose of aqueous penicillin G was 200,000 IU/kg of body weight. Data were recorded on admission, during disease evolution up to the 7th day of treatment, and at the final outcome. The results of hospitalization and the daily frequency of physical signs suggestive of pneumonia were assessed. The subgroups comprised 120 and 144 children who received aqueous penicillin G in 6 or 4 daily doses, respectively. Children≥5 years of age were more frequent in the 4-daily-doses subgroup (16.0% versus 4.2%; respectively, P=0.02). There were no differences between the compared subgroups in terms of final outcomes, lengths of hospitalization, durations of aqueous penicillin G use, frequencies of aqueous penicillin G substitution, or daily frequencies of tachypnea, fever, chest retraction, lower chest recession, nasal flaring, and cyanosis up to the 7th day of treatment. The studied posologic regimens were similarly effective in treating children hospitalized with a radiologically confirmed CAP diagnosis. Aqueous penicillin G (200,000 IU/kg/day) may be given in 4 daily doses to children with CAP.

Antibiotic therapy for pediatric community-acquired pneumonia: do we know when, what and for how long to treat?

Community-acquired pneumonia (CAP) is a common cause of morbidity among children in developed countries and accounts for an incidence of 10-40 cases per 1000 children in the first 5 years of life. Given the clinical, social and economic importance of CAP, there is general agreement that prompt and adequate therapy is essential to reduce the impact of the disease. The aim of this discussion paper is to consider critically the available data concerning the treatment of uncomplicated pediatric CAP and to consider when, how and for how long it should be treated. This review has identified the various reasons that make it difficult to establish a rational approach to the treatment of pediatric CAP, including the definition of CAP, the absence of a pediatric CAP severity score, the difficulty of identifying the etiology, limited pharmacokinetic (PK)/pharmacodynamic (PD) studies, the high resistance of the most frequent respiratory pathogens to the most widely used anti-infectious agents and the lack of information concerning the changes in CAP epidemiology following the introduction of new vaccines against respiratory pathogens. More research is clearly required in various areas, such as the etiology of CAP and the reasons for its complications, the better definition of first- and second-line antibiotic therapies (including the doses and duration of parenteral and oral antibiotic treatment), the role of antiviral treatment and on how to follow-up patients with CAP. Finally, further efforts are needed to increase vaccination coverage against respiratory pathogens and to conduct prospective studies of their impact.

Outcome of children hospitalized with community-acquired pneumonia treated with aqueous penicillin G

OBJECTIVE

To describe the evolution and outcome of children hospitalized with community-acquired pneumonia receiving penicillin.

METHODS

A search was carried out for all hospitalized community-acquired pneumonia cases in a 37-month period. Inclusion criteria comprised age >2 months, intravenous penicillin G use at 200,000 IU/kg/day for >48 h and chest x-ray results. Confounders leading to exclusion included underlying debilitating or chronic pulmonary illnesses, nosocomial pneumonia or transference to another hospital. Pneumonia was confirmed if a pulmonary infiltrate or pleural effusion was described by an independent radiologist blind to the clinical information. Data on admission and evolution were entered on a standardized form.

RESULTS

Of 154 studied cases, 123 (80%) and 40 (26%) had pulmonary infiltrate or pleural effusion, respectively. Penicilli was substituted by other antibiotics in 28 (18%) patients, in whom the sole significant decrease was in the frequency of tachypnea from the first to the second day of treatment (86% vs. 50%, p = 0.008). Among patients treated exclusively with penicillin G, fever (46% vs. 26%, p = 0.002), tachypnea (74% vs. 59%, p = 0.003), chest indrawing (29% vs. 13%, p<0.001) and nasal flaring (10% vs. 1.6%, p = 0.001) frequencies significantly decreased from admission to the first day of treatment. Patients treated with other antimicrobial agents stayed longer in the hospital than those treated solely with penicillin G (16 ± 6 vs. 8 ± 4 days, p<0.001, mean difference (95% confidence interval) 8 (6-10)). None of the studied patients died.

CONCLUSION

Penicillin G successfully treated 82% (126/154) of the study group and improvement was marked on the first day of treatment.

[Intrapleural streptokinase in the treatment of complicated parapneumonic empyema]

INTRODUCTION

Parapneumonic empyema is a frequent cause of admission in the Pediatric Hospital of the Pereira Rossell Hospital Center. In January 2005, we implemented a treatment protocol that included intrapleural streptokinase (STK) for children with complicated parapneumonic empyema as an alternative to surgery.

OBJECTIVES

To describe the results of intrapleural STK in the treatment of hospitalized children with complicated parapneumonic empyema and to compare these results with those of early thoracotomy.

PATIENTS AND METHODS

Children with complicated parapneumonic empyema admitted between January 1st 2004 and October 1st 2005 were included. The children were divided into two groups: a historical group, composed of children hospitalized between January 1st and December 31st 2004, treated with conventional thoracotomy before day 8 of chest drain placement and a prospective group, composed of children hospitalized between January 1st and October 1st 2005, treated with intrapleural STK before day 8 of chest drain placement. The variables used to compare outcome and treatment complications were duration of chest tube drainage after the treatment procedure, complications, re-admission, length of hospital stay, and death.

RESULTS

The results in both groups were similar. Length of hospital stay showed no significant differences. Duration of chest tube drainage after intrapleural STK was significantly shorter than after thoracotomy (p < 0.001). In the thoracotomy group a significantly higher proportion of patients required partial atypical pneumonectomy (p = 0.051). There were no deaths.

CONCLUSIONS

Intrapleural STK is a valid alternative for the treatment of children with complicated parapneumonic empyema.

Pharmacokinetics of penicillin g in very-low-birth-weight neonates

Data on the pharmacokinetics (PKs) of penicillin G (PEN) in neonates date back to the 1970s and do not include data for very-low-birth-weight (VLBW) neonates. The aim of this study was to describe the steady-state PKs and to establish an optimal regimen for the dosing of PEN in neonates with gestational ages of less than 28 weeks and birth weights of less than 1,200 g. Two PEN dosing regimens were studied: 50,000 IU (30 mg)/kg of body weight every 12 h (q12h) (group 1; n = 9) and 25,000 IU (15 mg)/kg q12h (group 2; n = 9). Samples for PK analysis were drawn before the injection of PEN and at 2 and 30 min and 1.5, 4, 8, and 12 h after intravenous injection of the third to eighth PEN doses. The PEN concentration was measured by a high-performance liquid chromatography with UV detection technique. The median peak and trough concentrations of PEN were 147 mug/ml (lower and upper quartiles, 109 and 157 mug/ml, respectively) and 7 mug/ml (lower and upper quartiles, 5 and 13 mug/ml, respectively) after administration of the dose of 50,000 IU and 59 mug/ml (lower and upper quartiles, 53 and 78 mug/ml, respectively) and 3 mug/ml (lower and upper quartiles, 3 and 4 mug/ml, respectively) after administration of the dose of 25,000 IU. The PEN half-life (median and lower and upper quartiles for group 1, 3.9 h and 3.3 and 7.0 h, respectively; median and lower and upper quartiles for group 2, 4.6 h and 3.8 and 5.6 h, respectively) was longer in VLBW neonates than in adults and term infants. PEN renal clearance correlated with creatinine clearance (R(2) = 0.309596; P = 0.038). Only a median of 34% (lower and upper quartiles, 28 and 37%, respectively) of the administered dose was excreted in urine within the following 12 h. We conclude that in VLBW infants a PEN dose of 25,000 IU (15 mg)/kg q12h is safe and sufficient to achieve serum concentrations above the MIC(90) for group B streptococci for the entire dosing interval.