Antimicrobial Resistant Streptococcus pneumoniae: Prevalence, Mechanisms, and Clinical Implications

Cost-Effectiveness of Vaccination with the 20-Valent Pneumococcal Conjugate Vaccine in the Italian Adult Population

The availability of a new 20-valent pneumococcal conjugate vaccine (PCV) makes it appropriate to assess its cost-effectiveness. This was evaluated by adopting the Italian National Health Service perspective, using a cost consequences Markovian model. The expected effects of vaccination with 20-valent PCV were compared with the administration of 13-valent PCV and 15-valent PCV. Assuming a 100% vaccination of cohorts aged 65-74 years, in the (lifetime) comparison between 20-valent PCV and 13-valent PCV, the former is dominant (lower cost for a better health outcome). A reduction in disease events was estimated: -1208 deaths; -1171 cases of bacteraemia; -227 of meningitis; -9845 hospitalised all-cause nonbacteremic pneumonia cases (NBP) and -21,058 non-hospitalised. Overall, in the Italian population, a total gain of 6581.6 life years and of 4734.0 QALY was estimated. On the cost side, against an increase in vaccinations costs (EUR +40.568 million), other direct health costs are reduced by EUR 48.032 million, with a net saving of EUR +7.464 million. The comparison between 20-valent PCV and 15-valent PCV results in an Incremental Cost-Effectiveness Ratio (ICER) of EUR 66 per life year gained and EUR 91 per QALY gained. The sensitivity analyses confirm the robustness of the results. We can conclude that the switch to 20-valent PCV is a sustainable and efficient investment.

Airway Epithelial Cell Junctions as Targets for Pathogens and Antimicrobial Therapy

Intercellular contacts between epithelial cells are established and maintained by the apical junctional complexes (AJCs). AJCs conserve cell polarity and build epithelial barriers to pathogens, inhaled allergens, and environmental particles in the respiratory tract. AJCs consist of tight junctions (TJs) and adherens junctions (AJs), which play a key role in maintaining the integrity of the airway barrier. Emerging evidence has shown that different microorganisms cause airway barrier dysfunction by targeting TJ and AJ proteins. This review discusses the pathophysiologic mechanisms by which several microorganisms (bacteria and viruses) lead to the disruption of AJCs in airway epithelial cells. We present recent progress in understanding signaling pathways involved in the formation and regulation of cell junctions. We also summarize the potential chemical inhibitors and pharmacological approaches to restore the integrity of the airway epithelial barrier. Understanding the AJCs-pathogen interactions and mechanisms by which microorganisms target the AJC and impair barrier function may further help design therapeutic innovations to treat these infections.

Prevalence, Antimicrobial Resistance, and Associated Factors of Streptococcus pneumoniae Colonization Rate among Old-Age Patients with Respiratory Tract Infection Attending Sheik Hassan Yebere Referral and Karamara General Hospitals, Jigjiga, Ethiopia

Background

Streptococcus pneumoniae is part of the normal flora of the upper respiratory tract of humans. Colonization of the upper respiratory tract (carriage of pneumococcus) by S. pneumoniae is considered a prerequisite for pneumococcal infection. It is the major cause of respiratory tract infection and frequent cause of physician visits, hospitalization, and death among old-aged patients because of their low immunity status. However, data on S. pneumoniae among old-aged patients in eastern Ethiopia are limited. This study was undertaken to determine the prevalence, antimicrobial resistance, and associated factor of S. pneumoniae colonization among old-aged patients.

Method

A health facility-based cross-sectional study was conducted from 1 March to 15 April 2020, at Sheik Hassan Yebere Referral and Karamara General Hospitals, Jigjiga, eastern Ethiopia. A total of 188 individuals greater than or equal to 60 years suspected of both upper and lower respiratory tract infections were included. Sociodemographic, behavioral, living conditions, and clinical data were collected by trained data collectors. Sputum samples were collected and examined for S. pneumoniae using the culture and biochemical tests as per the standard procedures. The Kirby–Bauer disk diffusion method was used for antimicrobial susceptibility testing. The data were entered on Epi-data version 3.1, and frequencies, crude odds ratio, and adjusted odds ratio were analyzed using SPSS version 20.

Results

The prevalence of S. pneumoniae colonization rate among old-aged patients was 13.8% (26/188) (95% CI: 9.6–19.1). Smoking (AOR = 3.3; 95% CI: 1.3–8.3), upper airway problems (AOR = 4.1; 95% CI: 1.1–15), and asthma disease (AOR = 3.1; 95% CI: 1.1–8.9) were the factors associated with S. pneumoniae colonization. The isolated organisms showed high antimicrobial resistance to trimethoprim-sulphamethoxazole (n = 12, 46.2%), tetracycline (n = 11, 42.3%), and ampicillin (n = 9, 34.6%).

Conclusion

This study showed that high prevalence of S. pneumoniae and antimicrobial resistance for trimethoprim-sulphamethoxazole, tetracycline, and ampicillin when compared to similar studies. Cigarette smoking, having upper airway problem, and asthma disease were factors associated with S. pneumoniae colonization. The provision of pneumococci conjugate vaccination and avoiding smoking are highly recommended for old aged in the community.

Association of pili with widespread multidrug-resistant genetic lineages of non-invasive pediatric Streptococcus pneumoniae isolates

The study aimed to evaluate the presence of pili in non-invasive pediatric pneumococcal isolates and to elucidate possible links with genetic lineages, serotypes, and antimicrobial resistance. We examined 147 Streptococcus pneumoniae isolates from children with respiratory tract infections and acute otitis media. Serotyping was performed by latex agglutination and capsule swelling reaction. Serogroup 6 was subjected to PCR-serotyping. Minimum inhibitory concentrations were determined according to EUCAST breakpoints. PCRs for rlrA and pitB genes were performed to detect a presence of type 1 and type 2 pili. MLST was conducted to define the clonal structure of the piliated strains. Almost all children (96.5%) were vaccinated with the pneumococcal conjugate vaccine PCV10. We detected 76.8% non-PCV10 - serotypes (NVTs) and 14.3% PCV10 serotypes. The predominant serotypes were NVTs: 19A (14.3%), 6C (12.2%), 3 (9.5%), 15A (7.5%) and 6A (6.8%). PI-1 was detected among 10.9% non-PCV10 serotypes 6A, 6C, and 19A and 6.1% PCV10 serotypes 19F and 23F. Type 2 pili were not found in the studied population. High levels of antimicrobial nonsusceptibility to erythromycin (58.5%), oral penicillin (55.8%), clindamycin (46.9%), trimethoprim-sulfamethoxazole (45.6%), tetracycline (39.5%) and ceftriaxone (16.3%) were revealed. The multidrug-resistant strains (MDR) were 55.1%. MLST represented 18 STs and three CCs among the piliated pneumococci: CC386, CC320, and CC81. More than half of the piliated strains (56.0%) belonged to successfully circulating international clones. PI-1 was associated mainly with MDR 6A, 6C, 19A, 19F, and 23F isolates from the widespread CC386, CC320, and CC81.

Exploration of Streptococcus core genome to reveal druggable targets and novel therapeutics against S. pneumoniae

Streptococcus pneumoniae (S. pneumoniae), the major etiological agent of community-acquired pneumonia (CAP) contributes significantly to the global burden of infectious diseases which is getting resistant day by day. Nearly 30% of the S. pneumoniae genomes encode hypothetical proteins (HPs), and better understandings of these HPs in virulence and pathogenicity plausibly decipher new treatments. Some of the HPs are present across many Streptococcus species, systematic assessment of these unexplored HPs will disclose prospective drug targets. In this study, through a stringent bioinformatics analysis of the core genome and proteome of S. pneumoniae PCS8235, we identified and analyzed 28 HPs that are common in many Streptococcus species and might have a potential role in the virulence or pathogenesis of the bacteria. Functional annotations of the proteins were conducted based on the physicochemical properties, subcellular localization, virulence prediction, protein-protein interactions, and identification of essential genes, to find potentially druggable proteins among 28 HPs. The majority of the HPs are involved in bacterial transcription and translation. Besides, some of them were homologs of enzymes, binding proteins, transporters, and regulators. Protein-protein interactions revealed HP PCS8235_RS05845 made the highest interactions with other HPs and also has TRP structural motif along with virulent and pathogenic properties indicating it has critical cellular functions and might go under unconventional protein secretions. The second highest interacting protein HP PCS8235_RS02595 interacts with the Regulator of chromosomal segregation (RocS) which participates in chromosome segregation and nucleoid protection in S. pneumoniae. In this interacting network, 54% of protein members have virulent properties and 40% contain pathogenic properties. Among them, most of these proteins circulate in the cytoplasmic area and have hydrophilic properties. Finally, molecular docking and dynamics simulation demonstrated that the antimalarial drug Artenimol can act as a drug repurposing candidate against HP PCS8235_RS 04650 of S. pneumoniae. Hence, the present study could aid in drugs against S. pneumoniae.

Antimicrobial Activity of Ceftaroline and Comparator Agents Against Ceftriaxone-Nonsusceptible Streptococcus pneumoniae from the United States (2008-2020)

We evaluated the activity of ceftaroline against clinical isolates of ceftriaxone-nonsusceptible Streptococcus pneumoniae from United States medical centers. Streptococcus pneumoniae isolates (n = 21,750) were consecutively collected from 201 medical centers in 2008-2020 and tested for susceptibility by broth microdilution method. Among these isolates, 1,419 (6.5%) were ceftriaxone-nonsusceptible (ceftriaxone minimum inhibitory concentration [MIC], ≥2 mg/L). Other resistant subgroups analyzed included multidrug-resistant (MDR; nonsusceptibility to ≥3 classes of agents; n = 4,454) and extensively drug-resistant (XDR; nonsusceptibility to ≥5 classes; n = 1,708) isolates. Ceftriaxone susceptibility increased from 89.0% (2008-2011) to 98.1% (2018-2020). Ceftaroline was active against 99.9% of ceftriaxone-nonsusceptible isolates (MIC_50/90, 0.25/0.25 mg/L) and retained potent activity against MDR (n = 4,454; MIC_50/90, 0.12/0.25 mg/L; >99.9% susceptible) and XDR (n = 1,708; MIC_50/90, 0.25/0.25 mg/L; 100.0% susceptible) isolates. Only one isolate had a ceftaroline MIC ≥0.5 mg/L. In summary, ceftaroline demonstrated potent and consistent activity over time (2008-2020) against a large collection of S. pneumoniae from U.S. medical centers, including ceftriaxone-nonsusceptible, MDR, and XDR isolates.

Streptococcus pneumoniae vaccination strategies and its expected impact on penicillin non-susceptibility in children under the age of five: Let's recap!

•

The efficacy of PCVs currently used in children under 5 years of age is threatened by the emergence of invasive and resistant non-vaccine serotypes worldwide.

•

Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings.

•

Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

The impact of pneumococcal conjugate vaccines (PCVs) on invasive pneumococcal disease (IPD) burden has been extensively studied in children aged<5 years; however, a pooled estimation of the effect of PCVs on penicillin non-susceptible pneumococci (PNSP) has not yet been performed. We aimed to identify whether the introduction of PCV-10 and PCV-13 had led to the decrease of the overall PNSP rate in children < 5 years. We conducted a systematic review of published surveillance studies reporting the rate of PNSP rates in children < 5 in countries where PCV10/13 were introduced. The overall observed trend onwards the introduction of PCV-10 and PCV-13 is a decrease in PNSP among children < 5 years in surveillance sites located in PCV-13 countries. We identified an increase of PNSP rates (serotype 19A) in PCV-10 settings. Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings. Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

Colonization by Streptococcus pneumoniae among children in Porto Velho, Rondônia, Western Brazilian Amazon

Streptococcus pneumoniae is one of the primary pathogens that are associated with acute respiratory infections (ARI) that cause high rates of morbidity and mortality among children under five years of age in developed and developing countries. This study aimed to determine the prevalence of nasopharyngeal colonization, the antimicrobial resistance profile, and the capacity for biofilm formation by S. pneumoniae isolated from children aged 0-6 years with ARI throughout the Porto Velho-RO. A total of 660 swabs were collected from children with ARI. Molecular and biochemical tests were performed to characterize the isolates. The disk-difusion method and the E-test were used for antimicrobial sensitivity testing (TSA). Biofilm formation capacity was assessed using microtiter plate assays, and serotype detection was acheived using polymerase chain reaction (PCR) analyses. The colonization rate for S. pneumoniae was 8.9% (59/660) and exhibited a high prevalence in children under 23 months of age 64.4% (38/59). The observed serotypes were 9V and 19F with frequencies of 1.7% (1/59) and 13.6% (8/59), respectively. The antimicrobial susceptibility test revealed 100% (59/59) sensitivity to vancomycin. In contrast, trimethoprim and oxacillin exhibited high resistance rates of 76.3% (45/59) and 52.5% (31/59), respectively. Of the biofilm-forming isolates, 54.8% (23/42) possessed resistance to some antimicrobials. In this study, S. pneumoniae showed high rates of antimicrobial resistance and the ability to form biofilms, as these are factors that favor bacterial persistence and can cause serious damage to the host.

Glucosylated nanoparticles for the oral delivery of antibiotics to the proximal small intestine protect mice from gut dysbiosis

Orally delivered antibiotics can reach the caecum and colon, and induce gut dysbiosis. Here we show that the encapsulation of antibiotics in orally administered positively charged polymeric nanoparticles with a glucosylated surface enhances absorption by the proximal small intestine through specific interactions of glucose and the abundantly expressed sodium-dependent glucose transporter 1. This improves bioavailability of the antibiotics, and limits their exposure to flora in the large intestine and their accumulation in caecal and faecal contents. Compared with the standard administration of the same antibiotics, the oral administration of nanoparticle-encapsulated ampicillin, chloramphenicol or vancomycin in mice with bacterial infections in the lungs effectively eliminated the infections, decreased adverse effects on the intestinal microbiota by protecting the animals from dysbiosis-associated metabolic syndromes and from opportunistic pathogen infections, and reduced the accumulation of known antibiotic-resistance genes in commensal bacteria. Glucosylated nanocarriers may be suitable for the oral delivery of other drugs causing gut dysbiosis.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

Increase of Macrolide-Resistance in Streptococcus pneumoniae Strains After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Lima, Peru

Streptococcus pneumoniae upper respiratory infections and pneumonia are often treated with macrolides, but recently macrolide resistance is becoming an increasingly important problem. The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the National Immunization Program of Peru in 2015. This study aimed to evaluate the temporal evolution of macrolide resistance in S. pneumoniae isolates collected in five cross-sectional studies conducted before and after this vaccine introduction, from 2006 to 2019 in Lima, Peru. A total of 521 and 242 S. pneumoniae isolates recovered from nasopharyngeal swabs from healthy carrier children < 2 years old (2 carriage studies) and samples from normally sterile body areas from pediatric patients with invasive pneumococcal disease (IPD) (3 IPD studies), respectively, were included in this study. Phenotypic macrolide resistance was detected using the Kirby-Bauer method and/or MIC test. We found a significant increase in macrolide resistance over time, from 33.5% to 50.0% in carriage studies, and from 24.8% to 37.5% and 70.8% in IPD studies. Macrolide resistance genes [erm(B) and mef(A/E)] were screened using PCR. In carriage studies, we detected a significant decrease in the frequency of mef(A/E) genes among macrolide-resistant S. pneumoniae strains (from 66.7% to 50.0%) after introduction of PCV13. The most common mechanism of macrolide-resistant among IPD strains was the presence of erm(B) (96.0%, 95.2% and 85.1% in the 3 IPD studies respectively). Macrolide resistance was more common in serotype 19A strains (80% and 90% among carriage and IPD strains, respectively) vs. non-serotype 19A (35.5% and 34.4% among carriage and IPD strains, respectively). In conclusion, S. pneumoniae macrolide resistance rates are very high among Peruvian children. Future studies are needed in order to evaluate macrolide resistance trends among pneumococcal strains, especially now after the COVID-19 pandemic, since azithromycin was vastly used as empiric treatment of COVID-19 in Peru.

Antimicrobial resistance among GLASS pathogens in Morocco: an epidemiological scoping review

BACKGROUND

Monitoring of antimicrobial resistance (AMR) is of great importance due to the frequency of strains becoming increasingly resistant to antibiotics. This review, using a public health focused approach, which aims to understand and describe the current status of AMR in Morocco in relation to WHO priority pathogens and treatment guidelines.

METHODS

PubMed, ScienceDirect and Google Scholar Databases and grey literature are searched published articles on antimicrobial drug resistance data for GLASS priority pathogens isolated from Morocco between January 2011 and December 2021. Articles are screened using strict inclusion/exclusion criteria. AMR data is extracted with medians and IQR of resistance rates.

RESULTS

Forty-nine articles are included in the final analysis. The most reported bacterium is Escherichia coli with median resistance rates of 90.9%, 64.0%, and 56.0%, for amoxicillin, amoxicillin-clavulanic acid, and co-trimoxazole, respectively. Colistin had the lowest median resistance with 0.1%. A median resistance of 63.0% is calculated for amoxicillin-clavulanic acid in Klebsiella pneumonia. Imipenem resistance with a median of 74.5% is reported for Acinetobacter baumannii. AMR data for Streptococcus pneumonie does not exceed 50.0% as a median.

CONCLUSIONS

Whilst resistance rates are high for most of GLASS pathogens, there are deficient data to draw vigorous conclusions about the current status AMR in Morocco. The recently join to the GLASS system surveillance will begin to address this data gap.

Identification of a two-component regulatory system involved in antimicrobial peptide resistance in Streptococcus pneumoniae

Two-component regulatory systems (TCS) are among the most widespread mechanisms that bacteria use to sense and respond to environmental changes. In the human pathogen Streptococcus pneumoniae, a total of 13 TCS have been identified and many of them have been linked to pathogenicity. Notably, TCS01 strongly contributes to pneumococcal virulence in several infection models. However, it remains one of the least studied TCS in pneumococci and its functional role is still unclear. In this study, we demonstrate that TCS01 cooperates with a BceAB-type ABC transporter to sense and induce resistance to structurally-unrelated antimicrobial peptides of bacterial origin that all target undecaprenyl-pyrophosphate or lipid II, which are essential precursors of cell wall biosynthesis. Even though tcs01 and bceAB genes do not locate in the same gene cluster, disruption of either of them equally sensitized the bacterium to the same set of antimicrobial peptides. We show that the key function of TCS01 is to upregulate the expression of the transporter, while the latter appears the main actor in resistance. Electrophoretic mobility shift assays further demonstrated that the response regulator of TCS01 binds to the promoter region of the bceAB genes, implying a direct control of these genes. The BceAB transporter was overexpressed and purified from E. coli. After reconstitution in liposomes, it displayed substantial ATPase and GTPase activities that were stimulated by antimicrobial peptides to which it confers resistance to, revealing new functional features of a BceAB-type transporter. Altogether, this inducible defense mechanism likely contributes to the survival of the opportunistic microorganism in the human host, in which competition among commensal microorganisms is a key determinant for effective host colonization and invasive path.

Macrolide Treatment Failure due to Drug–Drug Interactions: Real-World Evidence to Evaluate a Pharmacological Hypothesis

Macrolide antibiotics have received criticism concerning their use and risk of treatment failure. Nevertheless, they are an important class of antibiotics and are frequently used in clinical practice for treating a variety of infections. This study sought to utilize pharmacoepidemiology methods and pharmacology principles to estimate the risk of macrolide treatment failure and quantify the influence of their pharmacokinetics on the risk of treatment failure, using clinically reported drug–drug interaction data. Using a large, commercial claims database (2006–2015), inclusion and exclusion criteria were applied to create a cohort of patients who received a macrolide for three common acute infections. Furthermore, an additional analysis examining only bacterial pneumonia events treated with macrolides was conducted. These criteria were formulated specifically to ensure treatment failure would not be expected nor influenced by intrinsic or extrinsic factors. Treatment failure rates were 6% within the common acute infections and 8% in the bacterial pneumonia populations. Regression results indicated that macrolide AUC changes greater than 50% had a significant effect on treatment failure risk, particularly for azithromycin. In fact, our results show that decreased or increased exposure change can influence failure risk, by 35% or 12%, respectively, for the acute infection scenarios. The bacterial pneumonia results were less significant with respect to the regression analyses. This integration of pharmacoepidemiology and clinical pharmacology provides a framework for utilizing real-world data to provide insight into pharmacokinetic mechanisms and support future study development related to antibiotic treatments.

Emerging Roles of Extracellular Vesicles in Pneumococcal Infections: Immunomodulators to Potential Novel Vaccine Candidates

The Gram-positive bacterial pathogen, Streptococcus pneumoniae is a major global health threat that kills over one million people worldwide. The pneumococcus commonly colonizes the nasopharynx asymptomatically as a commensal, but is also capable of causing a wide range of life-threatening diseases such as pneumonia, meningitis and septicemia upon migration into the lower respiratory tract and spread to internal organs. Emergence of antibiotic resistant strains and non-vaccine serotypes has led to the classification of pneumococcal bacteria as a priority pathogen by the World Health Organization that needs urgent research into bacterial pathogenesis and development of novel vaccine strategies. Extracellular vesicles are spherical membrane bound structures that are released by both pathogen and host cells, and influence bacterial pathogenesis as well as the immune response. Recent studies have found that while bacterial vesicles shuttle virulence factors and toxins into host cells and regulate inflammatory responses, vesicles released from the infected host cells contain both bacterial and host proteins that are antigenic and immunomodulatory. Bacterial membrane vesicles have great potential to be developed as cell-free vaccine candidates in the future due to their immunogenicity and biostability. Host-derived vesicles isolated from patient biofluids such as blood and bronchoalveolar lavage could be used to identify potential diagnostic biomarkers as well as engineered to deliver desired payloads to specific target cells for immunotherapy. In this review, we summarize the recent developments on the role of bacterial and host vesicles in pneumococcal infections and future prospects in developing novel therapeutics and diagnostics for control of invasive pneumococcal diseases.

Bacterial profile, antimicrobial susceptibility patterns, and associated factors of community-acquired pneumonia among adult patients in Gondar, Northwest Ethiopia: A cross-sectional study

Introduction

Community-acquired pneumonia is associated with higher morbidity, hospitalization, and mortality in adults. Likewise, antimicrobial resistance has increased in recent decades in Ethiopia. Therefore, this study was aimed to determine the bacterial isolates, their antimicrobial susceptibility patterns, and factors associated with community-acquired pneumonia among adult patients in Gondar, Northwest Ethiopia.

Materials and methods

This institutional-based cross-sectional study was conducted from April to June 2021. Sociodemographic, clinical, and other relevant data were collected using a pre-tested questionnaire. A total of 312 sputum specimens were collected using sputum cups and inoculated into blood agar, chocolate agar, mannitol salt agar, and MacConkey agar plates, which were then incubated at 37°C for 24 hours. The bacterial isolates were identified based on Gram staining, colony characteristics, and biochemical tests. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. Inducible clindamycin resistance among the S. aureus isolates was detected by the D-test. Data were entered using EPI data version 4.6 and analyzed using SPSS version 20. P-value ≤ 0.05 at 95% CI was considered statistically significant.

Results

Of 312 cases, 39.4% (n = 123; 95% CI: 34.1%–44.9%) were found to have culture-confirmed pneumonia. The most common isolates were K. pneumoniae (31.0%, n = 39), S. pneumoniae (26.2%, n = 33), and S. aureus (20.6%, n = 26). The gram-positive bacteria were susceptible to chloramphenicol (100%) and clindamycin (96.6%). Gram-negative bacteria were susceptible to gentamicin (87.5%), azithromycin (87.1%), ciprofloxacin (86.6%), and ceftriaxone (79.0%) but highly resistant to ampicillin (100%), followed by tetracycline (87.1%), doxycycline (86.4%), co-trimoxazole (80.6%), and amoxicillin-clavulanic acid (79.0%). Overall, 72.2% of the isolates were multi-drug resistant to K. pneumoniae (94.9%, n = 37), E. coli (93.8%, n = 15), and S. pneumoniae (72.7%, n = 24). Only, 7.7% of S. aureus isolates showed inducible clindamycin resistance. Aging (AOR: 3.248, 95% CI: 1.001–10.545, p = 0.050), a history of pneumonia (AOR: 7.004, 95% CI: 3.591–13.658, p = 0.001), alcohol use (AOR: 6.614, 95% CI: 3.399–12.872, p < 0.001), and overcrowded living conditions (AOR: 4.348, 95% CI: 1.964–9.624, p = 0.001) were significantly associated with culture-positive sputum.

Conclusion and recommendations

This study found a high prevalence of bacteria-caused community-acquired pneumonia among adults and low susceptibility to ampicillin, tetracyclines, and amoxicillin-clavulanic acid. Therefore, culture-based bacterial identification and local antibiotic susceptibility testing should be performed regularly. Additionally, new insights into vaccine coverage against highly multi-drug resistant bacteria, particularly K. pneumoniae, are necessary.

Antimicrobial Susceptibility Pattern and Serotype Distribution of Streptococcus pneumoniae Isolates From a Hospital-Based Study in Chandigarh, North India

Streptococcus pneumoniae (pneumococcus) causes significant infection-related morbidity and mortality worldwide. The genome plasticity of pneumococcus is an essential factor in antibiotic resistance, serotype switching, and the emergence of nonvaccine serotypes. Information regarding the serotype distribution as well as antimicrobial susceptibility in pneumococcus clinical isolates responsible for various infections in Northern India is limited. Here, we have explored the antibiotic resistance and serotype pattern associated with S. pneumoniae infections from both invasive and noninvasive sites of patients of all ages, visiting out-patient department of a tertiary care hospital (PGIMER, Chandigarh, India). This study was carried out on 68 S. pneumoniae isolates and the isolates exhibited the highest resistance (76.5%) to cotrimaxozole followed by resistance toward tetracycline (36.8%) and erythromycin (23.5%). All isolates showed vancomycin susceptibility and 86.8% of isolates showed sensitivity to chloramphenicol. Multidrug resistance was found in 32% (n=22) of the S. pneumoniae isolates showing resistance toward three different antibiotics. Serotype 19F was found to be the most prevalent serotype (39%) followed by serotypes 6A/B/C (19%) and 1 (12%). These data shed light on the latest trends in antibiotic susceptibility and prevalent serotype patterns of hospital-based S. pneumoniae isolates. This information can be helpful in designing future disease-preventive strategies.

Novel 2,4-disubstituted quinazoline analogs as antibacterial agents with improved cytotoxicity profile: Modification of the benzenoid part

Bacterial resistance to currently used antibiotics demands the development of novel antibacterial agents with good safety margins and sufficient efficacy against multi-drug resistant isolates. We have previously described the synthesis of N-butyl-2-(butylthio)quinazolin-4-amine (I) as an optimized hit with broad-spectrum antibacterial activity and low cytotoxicity. In addition, we have identified a potential growing vector for this series of compounds. Herein, we describe further hit optimization which includes systematic diversifications of both the benzenoid part and the substituents at position 6 and 7 of compound I. Growing of the molecule beside the core modifications yielded several compounds with remarkable anti(myco)bacterial activity against a panel of pathogenic bacteria, including drug-resistant strains. Compound 12 showed a 2-4 fold improvement in activity than I against S. aureus Newman, S. pneumoniae DSM-20566 and E. faecalis DSM-20478. The compounds also showed a good safety profile towards human HepG2 cells.

Walking-induced exposure of biological particles simulated by a children robot with different shoes on public floors

Inhalation exposure to the resuspended biological particles from public places can cause adverse effects on human health. In this work, carpet dust samples were first collected from twenty example conference and hotel rooms by a vacuum cleaner. A bipedal robot was then used to simulate children's walking with three different shoes (cotton socks, PVC shoes and EVA shoes) in a hotel room. The particle resuspensions were simultaneously monitored by an aerosol spectrometer. In addition, air samples were also taken using a cyclone liquid impinger operated at 400 L min^-1, and further subjected to gene sequencing analysis. Our results showed that dominant bacterial genera in the carpet dusts included those containing respiratory pathogens such as Staphylococcus, Acinetobacter and Pseudomonas. The bacterial structures in carpet dusts were shown different among the samples from hotel and conference rooms (p < 0.05). Robot-walking resuspended a significant amount of particles from the floors, and different shoes have produced different size and concentration level particles (p < 0.05). Furthermore, walking was observed to resuspend more large particles than smaller ones for the studied range (0.3-10 μm). Robot walking induced increases in airborne Acinetobacter and Pseudomonas in breathing zones that were simulated for children. The results demonstrated that particle resuspension by walking was strongly influenced by particle size, biological species (particle properties), and shoe's sole material. The data from this work provide important information for people especially children aged 1-2 years to protect from resuspension exposure of biological agents when using public floors.

Interleukin-36 Cytokines in Infectious and Non-Infectious Lung Diseases

The IL-36 family of cytokines were identified in the early 2000’s as a new subfamily of the IL-1 cytokine family, and since then, the role of IL-36 cytokines during various inflammatory processes has been characterized. While most of the research has focused on the role of these cytokines in autoimmune skin diseases such as psoriasis and dermatitis, recent studies have also shown the importance of IL-36 cytokines in the lung inflammatory response during infectious and non-infectious diseases. In this review, we discuss the biology of IL-36 cytokines in terms of how they are produced and activated, as well as their effects on myeloid and lymphoid cells during inflammation. We also discuss the role of these cytokines during lung infectious diseases caused by bacteria and influenza virus, as well as other inflammatory conditions in the lungs such as allergic asthma, lung fibrosis, chronic obstructive pulmonary disease, cystic fibrosis and cancer. Finally, we discuss the current therapeutic advances that target the IL-36 pathway and the possibility to extend these tools to treat lung inflammatory diseases.

Antibiotic therapy in children with community-acquired pneumonia

PubMed was reviewed on antibiotic treatment of community-acquired pneumonia (CAP) in children for the years 2011-2020, and three clinical trials in high-income and eight in low-income countries were found. Prospective studies combining laboratory and clinical findings for steering of antibiotic treatment found that five-day courses were equally effective as longer courses. No new antibiotics were launched for children's CAP during the last 10 years. Five-day courses are equally effective as 7- to 10-day courses for CAP in children. Stewardship of antibiotics needs lessening of exposure to antibiotics by better targeting their use and by shortening the lengths of antibiotic courses.

Subcutaneous immunization with the fusion protein ΔA146Ply-SP0148 confers protection against Streptococcus pneumoniae infection

Pneumococcal SP0148 and pneumolysin (Ply) derivatives are important vaccine candidates. SP0148 is a conserved lipoprotein with high immunogenicity produced by Streptococcus pneumoniae. We have previously demonstrated that SP0148 can confer protection against fatal infections caused by S. pneumoniae. ΔA146Ply is a noncytotoxic mutant of Ply that retains the TLR4 agonistic effect and has mucosal and subcutaneous adjuvant activities suggested to induce protective immunity against S. pneumoniae infection. In this study, we constructed the fusion protein ΔA146Ply-SP0148, composed of ΔA146Ply and SP0148, and evaluated the immunoprotective effect of the fusion protein. When mice were subcutaneously immunized with the fusion protein ΔA146Ply-SP0148, high levels of anti-ΔA146Ply and anti-SP0148 IgG antibodies were induced in the serum. Specific antibodies can bind to a variety of different serotypes of S. pneumoniae. Compared with mice immunized with ΔA146Ply and SP0148 alone, mice immunized subcutaneously with the fusion protein ΔA146Ply-SP0148 with Al(OH)₃ had a higher survival rate when challenged by a lethal dose of S. pneumoniae, and they also had significantly lower lung bacterial loads and milder lung inflammation. In addition, mice immunized subcutaneously with the fusion protein ΔA146Ply-SP0148 stimulated strong Th1, Th2, and Th17 cell responses. In summary, these results suggest that subcutaneous immunization with the ΔA146Ply-SP0148 fusion protein can protect mice against fatal pneumococcal infection and lung infection. The fusion protein ΔA146ply-SP0148 can be a new pneumococcal vaccine target.

Phenotypic and genotypic characteristics of non-invasive S. pneumoniae isolates recovered from PCV10-vaccinated children in Bulgaria

PURPOSE

The non-invasive pneumococcal disease (NIPD) is a common infection during childhood. We aimed to define the clonal spread of pediatric non-invasive isolates recovered during the PCV10-period in Bulgaria concerning the serotype and antimicrobial susceptibility.

MATERIALS AND METHODS

Serogrouping/serotyping were performed using latex agglutination and capsular swelling reaction. Serogroup 6 strains were subjected to serotype-specific PCR's. The antibiotic susceptibilities were assessed by broth microdilution. MLST was performed to define the clonal composition.

RESULTS

We analyzed 154 pediatrics non-invasive S. pneumoniae isolates. The PCV10-vaccinated children were 94.1%. We disclosed 88% non-vaccine serotypes (NVTs) and 12% PCV10 - serotypes. All common serotypes among PCV10-vaccinated children (n ​= ​145) were non-vaccine types (NVTs): 19A (13.8%), 6C (11.7%), 3 (9.6%), 15A (8.3%) and 23A (5.5%). Antimicrobial non-susceptibility showed highest levels in erythromycin (50.0%), oral penicillin (49.4%), clindamycin (45.4%), trimethoprim-sulfamethoxazole (43.5%), tetracycline (42.2%), and ceftriaxone (14.3%). The multidrug-resistant strains (MDR) were 51.3%. MDR-serotypes were 6C (20.2%), 19A (17.7%), 15A (11.4%), 19F (10.1%), and 23A (8.9%). MLST presented 17 clonal complexes (CCs) with prevalence of CC320, CC386, CC505, CC8029 and CC2613 clustered 83% MDR isolates.

CONCLUSIONS

All emergent pediatric non-invasive serotypes in our geographic area during the studied PCV10-period were NVTs (19A, 6C, 3, 15A, and 23A). The fifth widespread CCs: CC320, CC386, CC505, CC8029 and CC2613 clustered 83% MDR isolates. Future surveillance of vaccine-induced changes in the clonality and the antimicrobial resistance of the pneumococcal population is needed.

The Effect of Impaired Polyamine Transport on Pneumococcal Transcriptome

Infections due to Streptococcus pneumoniae, a commensal in the nasopharynx, still claim a significant number of lives worldwide. Genome plasticity, antibiotic resistance, and limited serotype coverage of the available polysaccharide-based conjugate vaccines confounds therapeutic interventions to limit the spread of this pathogen. Pathogenic mechanisms that allow successful adaption and persistence in the host could be potential innovative therapeutic targets. Polyamines are ubiquitous polycationic molecules that regulate many cellular processes. We previously reported that deletion of polyamine transport operon potABCD, which encodes a putrescine/spermidine transporter (ΔpotABCD), resulted in an unencapsulated attenuated phenotype. Here, we characterize the transcriptome, metabolome, and stress responses of polyamine transport-deficient S. pneumoniae. Compared with the wild-type strain, the expression of genes involved in oxidative stress responses and the nucleotide sugar metabolism was reduced, while expression of genes involved in the Leloir, tagatose, and pentose phosphate pathways was higher in ΔpotABCD. A metabolic shift towards the pentose phosphate pathway will limit the synthesis of precursors of capsule polysaccharides. Metabolomics results show reduced levels of glutathione and pyruvate in the mutant. Our results also show that the potABCD operon protects pneumococci against hydrogen peroxide and nitrosative stress. Our findings demonstrate the importance of polyamine transport in pneumococcal physiology that could impact in vivo fitness. Thus, polyamine transport in pneumococci represents a novel target for therapeutic interventions.

Bacteriophage-Liposomes Complex, a Bi-therapy System to Target Streptococcus pneumonia and Biofilm: A Research Protocol

Introduction: Streptococcus pneumoniae is a gram-positive bacterium, which is the leading cause of death for young children, elderly population, and immunocompromised patients. Its ability to mutate and become resistant to some of the strongest antibiotics makes them difficult to treat and increases the risk of disease spread. Although the development of stronger antibiotics to treat such microbes may be an option, they potentially pose a dangerous threat to the body. As such, a viable treatment option to fight against antimicrobial resistance has yet been found. Methods: The study focuses on utilizing a bi-therapy system to target S. pneumoniae in biofilm, which is the site of emerging antibiotic resistant mutants, by creating levofloxacin-liposomes carrying phages and testing them both in vitro and in vivo. Anticipated results: Using bacteriophage therapy and applying bacteriophage-antibiotic synergy, it is hoped to augment the potency of the treatment while lowering its side-effects. The Cp-1 bacteriophage-liposomes complexes are expected to be specific to the S. pneumoniae to carry antibiotics to sites of infection. Discussion: The therapy could ensure targeted bacterial lysis and site-directed delivery of low-dose drugs to decrease the toxicity effect of the antibiotics. Once the efficacy is established and is proven to be significant, its potency can be tested in BALB/cByJ mice models before bringing this therapy to animal trials then human clinical trials. Conclusion: Bacteriophages are very attractive therapeutic agents that effectively target pathogenic bacteria, safe for the human body, and highly modifiable to combat newly emerging bacterial threats. In addition to its many benefits, the use of bacteriophages could significantly reduce healthcare costs. The potential use of bacteriophages-liposomes complexes could be translated to treat respiratory infections in humans after confirming its efficacy in vitro and in vivo studies.

Antimicrobial use in central nervous system infections

PURPOSE OF REVIEW

Central nervous system (CNS) infections are associated with high rates of morbidity and mortality. The purpose of this review is to summarize current antimicrobial therapies, as well as, updates in the management of community-acquired meningitis and healthcare-associated meningitis and ventriculitis.

RECENT FINDINGS

Due to the increasing rates of multidrug resistant and extensively-drug resistant organisms, available antimicrobials are limited. Novel treatment options include newer systemic antimicrobials and antimicrobials that have previously limited data in the management of CNS infections. Although limited by retrospective data, intrathecal (IT) and intraventricular (IVT) routes of administration offer the opportunity for antimicrobials that conventionally have minimal cerebrospinal fluid (CSF) penetration to achieve high CSF concentrations while minimizing systemic exposure.

SUMMARY

Updates in the use of systemic, IT, and IVT antimicrobials offer promise as therapeutic options for CNS infections. Additional pharmacokinetic and prospective data are needed to confirm these findings.

Emerging Treatment Options for Multi-Drug-Resistant Bacterial Infections

Antimicrobial resistance (AMR) remains one of the top public health issues of global concern. Among the most important strategies for AMR control there is the correct and appropriate use of antibiotics, including those available for the treatment of AMR pathogens. In this article, after briefly reviewing the most important and clinically relevant multi-drug-resistant bacteria and their main resistance mechanisms, we describe the emerging antimicrobial options for both MDR Gram-positive cocci and Gram-negative bacilli, including recently marketed agents, molecules just approved or under evaluation and rediscovered older antibiotics that have regained importance due to their antimicrobial spectrum. Specifically, emerging options for Gram-positive cocci we reviewed include ceftaroline, ceftobiprole, tedizolid, dalbavancin, and fosfomycin. Emerging treatment options for Gram-negative bacilli we considered comprise ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, aztreonam-avibactam, minocycline, fosfomycin, eravacycline, plazomicin, and cefiderocol. An exciting scenario is opening today with the long awaited growing availability of novel molecules for the treatment of AMR bacteria. Knowledge of mechanisms of action and resistance patterns allows physicians to increasingly drive antimicrobial treatment towards a precision medicine approach. Strict adherence to antimicrobial stewardship practices will allow us to preserve the emerging antimicrobials for our future.

In vitro susceptibility of common bacterial pathogens causing respiratory tract infections in Canada to lefamulin, a new pleuromutilin

Background

Community-acquired pneumonia (CAP) is a significant global health concern. Pathogens causing CAP demonstrate increasing resistance to commonly prescribed empiric treatments. Resistance in Streptococcus pneumoniae, the most prevalent bacterial cause of CAP, has been increasing worldwide, highlighting the need for improved antibacterial agents. Lefamulin, a novel pleuromutilin, is a recently approved therapeutic agent highly active against many lower respiratory tract pathogens. However, to date minimal data are available to describe the in vitro activity of lefamulin against bacterial isolates associated with CAP.

Methods

Common bacterial causes of CAP obtained from both lower respiratory and blood specimen isolates cultured by hospital laboratories across Canada were submitted to the annual CANWARD study's coordinating laboratory in Winnipeg, Canada, from January 2015 to October 2018. A total of 876 bacterial isolates were tested against lefamulin and comparator agents using the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method, and minimum inhibitory concentrations (MICs) were interpreted using accepted breakpoints.

Results

All S. pneumoniae isolates tested from both respiratory (n = 315) and blood specimens (n = 167) were susceptible to lefamulin (MIC ≤0.5 μg/mL), including isolates resistant to penicillins, clarithromycin, doxycycline, and trimethoprim-sulfamethoxazole. Lefamulin also inhibited 99.0% of Haemophilus influenzae isolates (regardless of β-lactamase production) (99 specimens; MIC ≤2 μg/mL) and 95.7% of methicillin-susceptible Staphylococcus aureus (MSSA) (MIC ≤0.25 μg/mL; 70 specimens) at their susceptible breakpoints. Conclusions: Lefamulin demonstrated potent in vitro activity against all respiratory isolates tested and may represent a significant advancement in empiric treatment options for CAP.

Is Penicillin-Nonsusceptible Streptococcus pneumoniae a Significant Challenge to Healthcare System? A Systematic Review and Meta-Analysis

BACKGROUND

In recent years, antibiotic-resistant pathogens including penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) have posed serious threats against human health. The aim of this meta-analysis was to investigate the prevalence of Streptococcus pneumoniae drug resistance particularly the incidence of PNSP strains in Iran.

METHODS

A systematic search was done in national and international electronic databases using Persian and English keywords. Up until May 20, 2020, a total of 58 publications were detected as eligible articles based on the inclusion and exclusion criteria, and then the selected studies were enrolled for data extraction and meta-analysis according to the PRISMA guidelines.

RESULTS

A high rate of PNSP (46.9%) and multidrug-resistant (MDR) S. pneumoniae (45.3%) in our isolates were evident. Furthermore, total frequency resistance to other drugs in S. pneumoniae was as follows: erythromycin 41.1%, azithromycin 53.2%, tetracycline 39.9%, levofloxacin 1.7%, rifampin 1.2%, clindamycin 31.7%, vancomycin 1.7%, trimethoprim/sulfamethoxazole 63.9%, chloramphenicol 20%, ceftriaxone 10.9%, amoxicillin 30.5%, ciprofloxacin 8.3%, imipenem 6.1%, linezolid 0%, and cefotaxime 8.3%.

CONCLUSION

Although the overall prevalence of cephalosporin- and carbapenem-resistant Streptococcus pneumoniae was low, penicillin-resistant strains, especially PNSP, could become a significant challenge to the healthcare system in Iran. Hence, the prescription of penicillin as the first-choice antibiotic in the treatment of S. pneumoniae infections should be avoided.

Prediction of human-Streptococcus pneumoniae protein-protein interactions using logistic regression

Streptococcus pneumoniae is a major cause of mortality in children under five years old. In recent years, the emergence of antibiotic-resistant strains of S. pneumoniae increases the threat level of this pathogen. For that reason, the exploration of S. pneumoniae protein virulence factors should be considered in developing new drugs or vaccines, for instance by the analysis of host-pathogen protein-protein interactions (HP-PPIs). In this research, prediction of protein-protein interactions was performed with a logistic regression model with the number of protein domain occurrences as features. By utilizing HP-PPIs of three different pathogens as training data, the model achieved 57-77 % precision, 64-75 % recall, and 96-98 % specificity. Prediction of human-S. pneumoniae protein-protein interactions using the model yielded 5823 interactions involving thirty S. pneumoniae proteins and 324 human proteins. Pathway enrichment analysis showed that most of the pathways involved in the predicted interactions are immune system pathways. Network topology analysis revealed β-galactosidase (BgaA) as the most central among the S. pneumoniae proteins in the predicted HP-PPI networks, with a degree centrality of 1.0 and a betweenness centrality of 0.451853. Further experimental studies are required to validate the predicted interactions and examine their roles in S. pneumoniae infection.

Antimicrobial Susceptibility Trends of Streptococcus pneumoniae by Age Groups Over Recent 10 Years in a Single Hospital in South Korea

PURPOSE

Streptococcus pneumoniae (S. pneumoniae) causes respiratory tract infections. Its non-vaccine serotypes and multidrug-resistant pneumococcal diseases have increased during the post-pneumococcal vaccination era. Therefore, it is important to understand the regional and age-related antimicrobial susceptibility of S. pneumoniae to select appropriate empirical antimicrobials.

MATERIALS AND METHODS

We retrospectively studied trends in the antimicrobial resistance of S. pneumoniae to commonly prescribed antibiotics in patient groups of various ages at a single teaching hospital in Jeju Island from 2009 to 2018.

RESULTS

In total, 1460 S. pneumoniae isolates were obtained during the study period. The overall antimicrobial resistance rates of S. pneumoniae to penicillin, erythromycin, ceftriaxone, levofloxacin, and vancomycin were 16.2%, 84.7%, 25.9%, 3.3%, and 0.0%, respectively, and the MDR rate was 6.7%. Erythromycin and ceftriaxone resistance rates increased by years; however, they were significantly reduced in adult groups. Levofloxacin resistance and MDR rates were also higher in adult groups. Overall, the MDR rate significantly increased during the recent 10 years, as well as in patients with a history of hospitalization within 90 days [odds ratio (OR)=3.58, 95% confidence interval (CI)=1.91-6.71] and sinusitis (OR=4.98, 95% CI=2.07-11.96).

CONCLUSION

Erythromycin and ceftriaxone resistance rates and the MDR rate of S. pneumoniae significantly increased during the recent 10 years; the trends in individual antimicrobial resistance rates significantly differed between the age groups. This study indicates the need for caution when using ceftriaxone as an empirical antimicrobial against pneumococcal infections.

[Current microbiological aspects of community respiratory infection beyond COVID-19]

From a microbiological point of view, both empirical and targeted antimicrobial treatment in respiratory infection is based on the sensitivity profile of isolated microorganisms and the possible resistance mechanisms that they may present. The latter may vary in different geographic areas according to prescription profiles and vaccination programs. Beta-lactam antibiotics, fluoroquinolones, and macrolides are the most commonly used antimicrobials during the exacerbations of chronic obstructive pulmonary disease and community-acquired pneumonia. In their prescription, different aspects such as intrinsic activity, bactericidal effect or their ability to prevent the development of resistance must be taken into account. The latter is related to the PK/PD parameters, the mutant prevention concentration and the so-called selection window. More recently, the potential ecological impact has grown in importance, not only on the intestinal microbiota, but also on the respiratory one. Maintaining the state of eubiosis requires the use of antimicrobials with a low profile of action on anaerobic bacteria. With their use, the resilience of the bacterial populations belonging to the microbiota, the state of resistance of colonization and the collateral damage related to the emergence of resistance to the antimicrobials in pathogens causing the infections and in the bacterial populations integrating the microbiota.

Sorting out the Superbugs: Potential of Sortase A Inhibitors among Other Antimicrobial Strategies to Tackle the Problem of Antibiotic Resistance

Rapid spread of antibiotic resistance throughout the kingdom bacteria is inevitably bringing humanity towards the "post-antibiotic" era. The emergence of so-called "superbugs"-pathogen strains that develop resistance to multiple conventional antibiotics-is urging researchers around the globe to work on the development or perfecting of alternative means of tackling the pathogenic bacteria infections. Although various conceptually different approaches are being considered, each comes with its advantages and drawbacks. While drug-resistant pathogens are undoubtedly represented by both Gram(+) and Gram(-) bacteria, possible target spectrum across the proposed alternative approaches of tackling them is variable. Numerous anti-virulence strategies aimed at reducing the pathogenicity of target bacteria rather than eliminating them are being considered among such alternative approaches. Sortase A (SrtA) is a membrane-associated cysteine protease that catalyzes a cell wall sorting reaction by which surface proteins, including virulence factors, are anchored to the bacterial cell wall of Gram(+) bacteria. Although SrtA inhibition seems perspective among the Gram-positive pathogen-targeted antivirulence strategies, it still remains less popular than other alternatives. A decrease in virulence due to inactivation of SrtA activity has been extensively studied in Staphylococcus aureus, but it has also been demonstrated in other Gram(+) species. In this manuscript, results of past studies on the discovery of novel SrtA inhibitory compounds and evaluation of their potency were summarized and commented on. Here, we discussed the rationale behind the inhibition of SrtA, raised some concerns on the comparability of the results from different studies, and touched upon the possible resistance mechanisms as a response to implementation of such therapy in practice. The goal of this article is to encourage further studies of SrtA inhibitory compounds.

Epidemiological analysis of pneumococcal strains isolated at Yangon Children's Hospital in Myanmar via whole-genome sequencing-based methods

Streptococcus pneumoniae causes over one million deaths from lower respiratory infections per annum worldwide. Although mortality is very high in Southeast Asian countries, molecular epidemiological information remains unavailable for some countries. In this study, we report, for the first time, the whole-genome sequences and genetic profiles of pneumococcal strains isolated in Myanmar. We isolated 60 streptococcal strains from 300 children with acute respiratory infection at Yangon Children's Hospital in Myanmar. We obtained whole-genome sequences and identified the species, serotypes, sequence types, antimicrobial resistance (AMR) profiles, virulence factor profiles and pangenome structure using sequencing-based analysis. Average nucleotide identity analysis indicated that 58 strains were S. pneumoniae and the other 2 strains were Streptococcus mitis. The major serotype was 19F (11 strains), followed by 6E (6B genetic variant; 7 strains) and 15 other serotypes; 5 untypable strains were also detected. Multilocus sequence typing analysis revealed 39 different sequence types, including 11 novel ones. In addition, genetic profiling indicated that AMR genes and mutations spread among pneumococcal strains in Myanmar. A minimum inhibitory concentration assay indicated that several pneumococcal strains had acquired azithromycin and tetracycline resistance, whereas no strains were found to be resistant against levofloxacin and high-dose penicillin G. Phylogenetic and pangenome analysis showed various pneumococcal lineages and that the pneumococcal strains contain a rich and mobile gene pool, providing them with the ability to adapt to selective pressures. This molecular epidemiological information can help in tracking global infection and supporting AMR control in addition to public health interventions in Myanmar.

Omadacycline vs moxifloxacin in adults with community-acquired bacterial pneumonia

OBJECTIVE

Community-acquired bacterial pneumonia (CABP) is a major clinical burden worldwide. In the phase III OPTIC study (NCT02531438) in CABP, omadacycline was found to be non-inferior to moxifloxacin for investigator-assessed clinical response (IACR) at post-treatment evaluation (PTE, 5-10 days after last dose). This article reports the efficacy findings, as specified in the European Medicines Agency (EMA) guidance.

METHODS

Patients were randomized 1:1 to omadacycline 100 mg intravenously (every 12 h for two doses, then every 24 h) with optional transition to 300 mg orally after 3 days, or moxifloxacin 400 mg intravenously (every 24 h) with optional transition to 400 mg orally after 3 days. The total treatment duration was 7-14 days. The primary endpoint for EMA efficacy analysis was IACR at PTE in patients with Pneumonia Patient Outcomes Research Team (PORT) risk class III and IV.

RESULTS

In total, 660 patients were randomized as PORT risk class III and IV. Omadacycline was non-inferior to moxifloxacin at PTE. The clinical success rates were 88.4% and 85.2%, respectively [intent-to-treat population; difference 3.3; 97.5% confidence interval (CI) -2.7 to 9.3], and 92.5% and 90.5%, respectively (clinically evaluable population; difference 2.0; 97.5% CI 3.2-7.4). Clinical success rates with omadacycline and moxifloxacin were similar against identified pathogens and across key subgroups.

CONCLUSIONS

Omadacycline was non-inferior to moxifloxacin for IACR at PTE, with high clinical success across pathogen types and patient subgroups.

The search for novel treatment strategies for Streptococcus pneumoniae infections

This review provides an overview of the most important novel treatment strategies against Streptococcus pneumoniae infections published over the past 10 years. The pneumococcus causes the majority of community-acquired bacterial pneumonia cases, and it is one of the prime pathogens in bacterial meningitis. Over the last 10 years, extensive research has been conducted to prevent severe pneumococcal infections, with a major focus on (i) boosting the host immune system and (ii) discovering novel antibacterials. Boosting the immune system can be done in two ways, either by actively modulating host immunity, mostly through administration of selective antibodies, or by interfering with pneumococcal virulence factors, thereby supporting the host immune system to effectively overcome an infection. While several of such experimental therapies are promising, few have evolved to clinical trials. The discovery of novel antibacterials is hampered by the high research and development costs versus the relatively low revenues for the pharmaceutical industry. Nevertheless, novel enzymatic assays and target-based drug design, allow the identification of targets and the development of novel molecules to effectively treat this life-threatening pathogen.

A New Phage Lysin Isolated from the Oral Microbiome Targeting Streptococcus pneumoniae

Streptococcus pneumoniae is highly pathogenic and causes several mucosal and invasive infections. Due to the rising number of multidrug-resistant (MDR) strains of S. pneumoniae, new antimicrobials with alternative mechanisms of action are urgently needed. In this study, we identified two new Streptococcal phages from the oral microbiome, 23TH and SA01. Their lysins, 23TH_48 and SA01_53, were recombinantly expressed, characterized and tested for their lethality. SA01_53 was found to only lyse its host strain of S. anginosus, while 23TH_48 was found to possess a broader lytic activity beyond its host strain of S. infantis, with several S. pneumoniae isolates sensitive to its lytic activity. 23TH_48 at a concentration of five activity units per mL (U/mL) was found to reduce cell counts of S. pneumoniae DSM 24048 by 4 log₁₀ colony forming units per mL (CFU/mL) within 1 h and effectively prevented and destroyed biofilms of S. pneumoniae R6 at concentrations of 228.8 ng/µL and 14.3 ng/µL, respectively. Given its high lytic activity, 23TH_48 could prove to be a promising candidate to help combat pneumococcal infections.

The Many Roles of the Bacterial Second Messenger Cyclic di-AMP in Adapting to Stress Cues

Bacteria respond to changes in environmental conditions through adaptation to external cues. Frequently, bacteria employ nucleotide signaling molecules to mediate a specific, rapid response. Cyclic di-AMP (c-di-AMP) was recently discovered to be a bacterial second messenger that is essential for viability in many species. In this review, we highlight recent work that has described the roles of c-di-AMP in bacterial responses to various stress conditions. These studies show that depending on the lifestyle and environmental niche of the bacterial species, the c-di-AMP signaling network results in diverse outcomes, such as regulating osmolyte transport, controlling plant attachment, or providing a checkpoint for spore formation. c-di-AMP achieves this signaling specificity through expression of different classes of synthesis and catabolic enzymes as well as receptor proteins and RNAs, which will be summarized.

Identification of Streptococcus pneumoniae and other Mitis streptococci: importance of molecular methods

The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower pathogenicity. In clinical practice, some representatives of these species, especially Streptococcus pseudopneumoniae and Streptococcus mitis, are sometimes mistaken for S. pneumoniae based on the results of classical microbiological methods, such as optochin susceptibility and bile solubility. Several various molecular approaches that address the issue of correct identification of pneumococci and other Mitis streptococci have been proposed and are discussed in this review, including PCR- and gene sequencing-based tests as well as new developments in the genomic field that represents an important advance in our understanding of relationships within the Mitis group.

Investigational and Experimental Drugs for Community-Acquired Pneumonia: the Current Evidence

Community-acquired pneumonia (CAP) is a common infection with a constantly evolving etiological spectrum. This changing etiology conditions the adequate selection of optimal therapeutic regimens, both in empirical and definitive treatments. In recent years, new antimicrobials have been approved by regulatory authorities for use in CAP, although it is necessary to continue incorporating new antimicrobial agents that improve the activity profile in relation to the appearance of bacterial resistance in certain pathogens, such as pneumococcus, Staphylococcus aureus or Pseudomonas aeruginosa. Delafloxacin, omadacycline and lefamulin are the most recently approved antibiotics for CAP. These three antibiotics have shown non-inferiority to their comparators for the treatment of CAP with an excellent safety profile. However, in the 2019 ATS/IDSA guidelines, it has been considered that more information is needed to incorporate these new drugs into community-based treatment. New antimicrobials, such as solithromycin and nemonoxacin, are currently being studied in Phase III clinical trials. Both drugs have shown non-inferiority against the comparators and an acceptable safety profile; however, they have not yet been approved by the regulatory authorities. Several drugs are being tested in Phase I and II clinical trials. These include zabofloxacin, aravofloxacin, nafithromycin, TP-271, gepotidacin, radezolid, delpazolid, and CAL02. The preliminary results of these clinical trials allow us to assure that most of these drugs may play a role in the future treatment of CAP.

Antibiotics in Food Chain: The Consequences for Antibiotic Resistance

Antibiotics have been used as essential therapeutics for nearly 100 years and, increasingly, as a preventive agent in the agricultural and animal industry. Continuous use and misuse of antibiotics have provoked the development of antibiotic resistant bacteria that progressively increased mortality from multidrug-resistant bacterial infections, thereby posing a tremendous threat to public health. The goal of our review is to advance the understanding of mechanisms of dissemination and the development of antibiotic resistance genes in the context of nutrition and related clinical, agricultural, veterinary, and environmental settings. We conclude with an overview of alternative strategies, including probiotics, essential oils, vaccines, and antibodies, as primary or adjunct preventive antimicrobial measures or therapies against multidrug-resistant bacterial infections. The solution for antibiotic resistance will require comprehensive and incessant efforts of policymakers in agriculture along with the development of alternative therapeutics by experts in diverse fields of microbiology, biochemistry, clinical research, genetic, and computational engineering.

Psp140: an immunodominant antigen in the supernatant of Streptococcus pneumoniae culture

Background and Objectives:

Streptococcus pneumoniae causes many lethal infections. Due to its reduced sensitivity to commonly used antibiotics, development of new strategies against pneumococcal infections seems to be necessary. We aimed to investigate immunodominant antigens in S. pneumoniae culture supernatant in order to develop novel targets for pneumococcal vaccines.

Materials and Methods:

In this study S. pneumoniae ATCC49619 was sub-cultured into BHI broth from overnight culture at 37°C for 4 h. The supernatant proteins were precipitated using acetone precipitation method. A rabbit was intramuscularly immunized with alum adjuvant and 100 μg pneumococcal supernatant proteins, 6 times at 14 days’ intervals to produce hyperimmune serum. ELISA assay was performed to determine the antibody level response to pneumococcal secretory proteins. Then dot blot applied for rapid evaluation of hyperimmune serum reactivity to pneumococcus supernatant proteins. The western blot was also used to determine the interaction of supernatant proteins with immunogenic rabbit’s hyperimmune-serum.

Results:

According to the western blot analysis, the immunodominant protein had 140KDa molecular weight and designated as pneumococcal secretory protein140 (Psp140).

Conclusion:

The Psp140 protein in the supernatant of S. pneumoniae culture is an immunodominant protein and it is likely related to pneumococcal secretory protein or surface exposed protein which released into culture supernatant during bacterial growth.

Venom peptides in association with standard drugs: a novel strategy for combating antibiotic resistance - an overview

Development of antibiotic resistance that leads to resurgence of bacterial infections poses a threat to disease-free existence for humankind and is a challenge for the welfare of the society at large. Despite research efforts directed towards treatment of pathogens, antibiotics within new improved classes have not emerged for years, a fact largely attributable to the pharmacological necessities compelling drug development. Recent reversion to the use of natural products alone or in combination with standard drugs has opened up new vistas for alternative therapeutics. The success of this strategy is evident in the sudden interest in plant extracts as additives/synergists for treatment of maladies caused by drug-resistant bacterial strains. Animal venoms have long fascinated scientists as sources of pharmacologically active components that can be exploited for the treatment of specific ailments and should be promoted further to clinical trials. In the present review, we outline the scope and possible methods for the applications of animal venoms in combination with commercial antibiotics to offer a better treatment approach against antibiotic-resistant infections.

Pneumococcal susceptibility to antibiotics in carriage: a 17 year time series analysis of the adaptive evolution of non-vaccine emerging serotypes to a new selective pressure environment

BACKGROUND

Pneumococcal conjugate vaccine (PCV) implementations led to major changes in serotype distribution and antibiotic resistance in carriage, accompanied by changes in antibiotic consumption.

OBJECTIVES

To assess the dynamic patterns of antimicrobial non-susceptibility across non-PCV13 serotypes following PCV implementations.

METHODS

We conducted a quasi-experimental interrupted time series analysis based on a 17 year French nationwide prospective cohort. From 2001 to 2018, 121 paediatricians obtained nasopharyngeal swabs from children with acute otitis media who were aged 6 months to 2 years. The main outcome was the rate of penicillin-non-susceptible pneumococci (PNSP), analysed by segmented regression.

RESULTS

We enrolled 10 204 children. After PCV13 implementation, the PNSP rate decreased (-0.5% per month; 95% CI -0.9 to -0.1), then, after 2014, the rate slightly increased (+0.7% per month; 95% CI +0.2 to +1.2). Global antibiotic use within the previous 3 months decreased over the study period (-22.2%; 95% CI -33.0 to -11.3), but aminopenicillin use remained high. Among the main non-PCV13 serotypes, four dynamic patterns of penicillin susceptibility evolution were observed, including unexpected patterns of serotypes emerging while remaining or even becoming penicillin susceptible. In contrast to PNSP strains, for these latter patterns, the rate of co-colonization with Haemophilus influenzae increased concomitant with their emergence.

CONCLUSIONS

In a context of continuing high antibiotic selective pressure, a progressive increase in PNSP rate was observed after 2014. However, we highlighted an unexpected variability in dynamic patterns of penicillin susceptibility among emerging non-PCV13 serotypes. Antibiotic resistance may not be the only adaptive mechanism to antimicrobial selective pressure, and co-colonization with H. influenzae may be involved.

Mass Balance Study of the Engineered Cationic Antimicrobial Peptide, WLBU2, Following a Single Intravenous Dose of 14C-WLBU2 in Mice

BACKGROUND

To address multidrug resistance, we developed engineered Cationic Antimicrobial Peptides (eCAPs). Lead eCAP WLBU2 displays potent activity against drug-resistant bacteria and effectively treats lethal bacterial infections in mice, reducing bacterial loads to undetectable levels in diverse organs.

OBJECTIVE

To support the development of WLBU2, we conducted a mass balance study.

METHODS

CD1 mice were administered 10, 15, 20 and 30 mg/kg of QDx5 WLBU2 or a single dose of [14C]-WLBU2 at 15 mg/kg IV. Tolerability, tissue distribution and excretion were evaluated with liquid scintillation and HPLC-radiochromatography.

RESULTS

The maximum tolerated dose of WLBU2 is 20 mg/kg IV. We could account for greater than >96% of the radioactivity distributed within mouse tissues at 5 and 15 min. By 24h, only ~40-50% of radioactivity remained in the mice. The greatest % of the dose was present in liver, accounting for ~35% of radioactivity at 5 and 15 min, and ~ 8% of radioactivity remained at 24h. High radioactivity was also present in kidneys, plasma, red blood cells and lungs, while less than 0.2% of radioactivity was present in brain, fat, or skeletal muscle. Urinary and fecal excretion accounted for 12.5 and 2.2% of radioactivity at 24h.

CONCLUSION

WLBU2 distributes widely to mouse tissues and is rapidly cleared with a terminal radioactivity half-life of 22 h, a clearance of 27.4 mL/h/kg, and a distribution volume of 0.94 L/kg. At 2-100 μg-eq/g, the concentrations of 14C-WLBU2 appear high enough in the tissues to account for the inhibition of microbial growth.

Bacteriophages and the One Health Approach to Combat Multidrug Resistance: Is This the Way?

Antimicrobial resistance necessitates action to reduce and eliminate infectious disease, ensure animal and human health, and combat emerging diseases. Species such as Acinetobacter baumanniii, vancomycin resistant Enterococcus, methicillin resistance Staphylococcus aureus, and Pseudomonas aeruginosa, as well as other WHO priority pathogens, are becoming extremely difficult to treat. In 2017, the EU adopted the “One Health” approach to combat antibiotic resistance in animal and human medicine and to prevent the transmission of zoonotic disease. As the current therapeutic agents become increasingly inadequate, there is a dire need to establish novel methods of treatment under this One Health Framework. Bacteriophages (phages), viruses infecting bacterial species, demonstrate clear antimicrobial activity against an array of resistant species, with high levels of specificity and potency. Bacteriophages play key roles in bacterial evolution and are essential components of all ecosystems, including the human microbiome. Factors such are their specificity, potency, biocompatibility, and bactericidal activity make them desirable options as therapeutics. Issues remain, however, relating to their large-scale production, formulation, stability, and bacterial resistance, limiting their implementation globally. Phages used in therapy must be virulent, purified, and well characterized before administration. Clinical studies are warranted to assess the in vivo pharmacokinetics and pharmacodynamic characteristics of phages to fully establish their therapeutic potential.