Microbial virulence, molecular epidemiology and pathogenic factors of fluoroquinolone-resistant Haemophilus influenzae infections in Guangzhou, China

Molecular characteristics and biofilm formation capacity of nontypeable Haemophilus influenza strains isolated from lower respiratory tract in children

With the widespread introduction of the Hib conjugate vaccine, Nontypeable Haemophilus influenzae (NTHi) has emerged as the predominant strain globally. NTHi presents a significant challenge as a causative agent of chronic clinical infections due to its high rates of drug resistance and biofilm formation. While current research on NTHi biofilms in children has primarily focused on upper respiratory diseases, investigations into lower respiratory sources remain limited. In this study, we collected 54 clinical strains of lower respiratory tract origin from children. Molecular information and drug resistance features were obtained through whole gene sequencing and the disk diffusion method, respectively. Additionally, an in vitro biofilm model was established. All clinical strains were identified as NTHi and demonstrated the ability to form biofilms in vitro. Based on scanning electron microscopy and crystal violet staining, the strains were categorized into weak and strong biofilm-forming groups. We explored the correlation between biofilm formation ability and drug resistance patterns, as well as clinical characteristics. Stronger biofilm formation was associated with a longer cough duration and a higher proportion of abnormal lung imaging findings. Frequent intake of β-lactam antibiotics might be associated with strong biofilm formation. While a complementary relationship between biofilm-forming capacity and drug resistance may exist, further comprehensive studies are warranted. This study confirms the in vitro biofilm formation of clinical NTHi strains and establishes correlations with clinical characteristics, offering valuable insights for combating NTHi infections.

First global report about the prevalence of multi-drug resistant Haemophilus influenzae: a systematic review and meta-analysis

BACKGROUND

In recent decades, the prevalence of antibiotic resistance is increasing in Haemophilus influenzae (Haemophilus influenzae), which poses important challenges to global health. This research offers a comprehensive meta-analysis of the global epidemiology of multi-drug resistant (MDR) H. influenzae.

METHODS

In this study, we conducted a meta-analysis based on PRISMA checklist. Electronic databases including PubMed, ISI Web of Science, Scopus, EMBASE, and Google Scholar were reviewed using keywords related to H. influenzae and antibiotic resistance. Eligible studies were selected based on stringent inclusion and exclusion criteria. Then, data from these studies were analyzed using the Comprehensive Meta-Analysis (CMA) software.

RESULTS

Of 375 retrieved articles, 16 met the inclusion criteria. These studies were conducted from 2003 to 2023 and analyzed data from 19,787 clinical isolates of H. influenzae. The results showed different levels of resistance of H. influenzae to different antibiotics: ampicillin (36%), azithromycin (15.3%), ceftriaxone (1.4%), etc. The global prevalence for beta-lactamases producing H. influenzae and MDR H. influenzae was measured 34.9% and 23.1%, respectively. The prevalence rate of MDR H. influenzae was higher in Asian countries (24.6%) compared to Western regions (15.7%). MDR H. influenzae had the highest prevalence in meningitis cases (46.9%) and the lowest prevalence in acute otitis media (0.5%).

CONCLUSIONS

The prevalence of MDR H. influenzae has been increasing worldwide, especially in Asian regions. This highlights the urgent need for monitoring and implementation of effective antibiotic stewardship programs globally.

National Danish surveillance of invasive clinical Haemophilus influenzae isolates and their resistance profile

INTRODUCTION

This study aimed to investigate the epidemiology, serotype distribution, phenotypical antibiogram, and molecular resistance gene characteristics of invasive Haemophilus influenzae infections in Denmark from 2014 to 2022. Additionally, the potential impact of outdoor temperature and COVID-19 restrictions on the epidemiology of H. influenzae was assessed.

MATERIALS AND METHODS

Invasive H. influenzae isolates were received from patients with positive culture results from cerebrospinal fluid, blood, or other sterile sites. Sample data were obtained from the Danish laboratory surveillance system/MiBa database, and whole-genome sequencing (WGS) was performed on the isolates. The incidence rates and distribution of H. influenzae cases were analyzed, and antibiotic susceptibility were assessed.

RESULTS

A total of 1,007 invasive H. influenzae cases were identified, with serotyping conducted for 752 (74.7%) isolates. The median incidence per year of H. influenzae was 2.0 cases per 100,000, with the highest incidence in 2014 and the lowest in 2020. The majority of H. influenzae isolates were non-typeable H. influenzae (NTHi), while the most prominent serotypes were serotype f followed by serotype b. Bacteremia cases accounted for the majority (88.6%) of occurrences, although meningitis cases showed an increasing trend during the time period. The age group 85+ exhibited the highest incidence. The implementation of COVID-19 preventive interventions in 2020 resulted in a significant reduction in H. influenzae incidence, which returned to pre-COVID levels in 2021. A negative correlation was observed between monthly H. influenzae cases and outdoor temperature. An overall level of genetic beta-lactamase resistance of 26.3% was observed divided into 10.6% beta-lactamase-positive ampicillin-resistant (gBLPAR), 13.6% beta-lactamase-negative ampicillin-resistant (gBLNAR) and 2.1% beta-lactamase-positive amoxicillin clavulanate-resistant (gBLPACR). Other non-beta-lactam resistance traits were detected in 7.6% of isolates (primarily aminoglycoside-modifying enzymes).

CONCLUSION

The overall incidence of H. influenzae in Denmark returned to stable levels after the COVID-19 epidemic, with NTHi strains dominating. The COVID-19 preventive interventions led to a major reduction in incidence. A significant negative correlation between the incidence of H. influenzae and temperature was observed. The study revealed an overall genetic beta-lactam resistance rate of 26.3%, and the concordance between genotypic and phenotypic beta-lactam resistance was high (98.2%).

Epidemic Trends and Biofilm Formation Mechanisms of Haemophilus influenzae: Insights into Clinical Implications and Prevention Strategies

Haemophilus influenzae (H. influenzae) is a significant pathogen responsible for causing respiratory tract infections and invasive diseases, leading to a considerable disease burden. The Haemophilus influenzae type b (Hib) conjugate vaccine has notably decreased the incidence of severe infections caused by Hib strains, and other non-typable H. influenzae (NTHi) serotypes have emerged as epidemic strains worldwide. As a result, the global epidemic trends and antibiotic resistance characteristics of H. influenzae have been altered. Researches on the virulence factors of H. influenzae, particularly the mechanisms underlying biofilm formation, and the development of anti-biofilm strategies hold significant clinical value. This article provides a summary of the epidemic trends, typing methods, virulence factors, biofilm formation mechanisms, and prevention strategies of H. influenzae. The increasing prevalence of NTHi strains and antibiotic resistance among H. influenzae, especially the high β-lactamase positivity and the emergence of BLNAR strains have increased clinical difficulties. Understanding its virulence factors, especially the formation mechanism of biofilm, and formulating effective anti-biofilm strategies may help to reduce the clinical impact. Therefore, future research efforts should focus on developing new approaches to prevent and control H. influenzae infections.

Molecular Epidemiology and Antibiotic Resistance Analysis of Non-Typeable Haemophilus influenzae (NTHi) in Guangzhou: A Representative City of Southern China

This study aimed to investigate the molecular epidemiology and antibiotic resistance of Haemophilus influenzae in Guangzhou, China. A total of 80 H. influenzae isolates were collected from the First Affiliated Hospital of Guangzhou Medical University from January 2020 to April 2021. Species identification, antimicrobial susceptibility, molecular capsular typing, multilocus sequence typing and the clinical characteristics analysis of patients were performed. For all recruited isolates, the majority of H. influenzae strains from patients with respiratory symptoms were found to be non-typeable H. influenzae (NTHi). The isolates were relative susceptible to third- and fourth-generation cephalosporins, quinolones and chloramphenicol, despite having a high ampicillin resistance rate (>70%). The genotyping results reveal a total of 36 sequence types (STs), with ST12 being the most prevalent ST. Remarkably, the 36 STs identified from 80 NTHi isolates within a short period of 15 months and in a single medical setting have revealed a high genetic diversity in NTHi isolates. In comparison, it is noteworthy that the most prevalent STs found in the present study have rarely been found to overlap with those from previous studies. This is the first study on the molecular epidemiology of NTHi isolates in Guangzhou, a city that is representative of southern China.

Molecular epidemiology and antimicrobial resistance of Haemophilus influenzae in Guiyang, Guizhou, China

Background

The widespread use of antimicrobials and Haemophilus influenzae type b (Hib) vaccine worldwide has altered the epidemiological patterns of invasive H. influenzae. Nonetheless, little is currently known on the epidemiological characteristics of H. influenzae in Guiyang, Guizhou, China.

Objective

To determine the serotype distribution, antimicrobial resistance and Multilocus Sequence Typing (MLST) of H. influenzae in hospitalized patients in Guiyang City.

Methods

A total of 196 clinical isolates from hospitalized patients were collected. Serotypes were determined according to the specific capsule gene, bexA, amplified by PCR. According to the guidelines of Clinical and Laboratory Standards Institute (CLSI) 2020 drug susceptibility tested, and the results determined. The chromogenic cephalosporin nitrocefin method was used to detect β-lactamase production, β-lactamase negative, ampicillin-resistant (BLNAR) strains were detected by PCR amplification and sequencing of the penicillin-binding protein 3 (PBP3) locus of ftsI. Multilocus Sequence Typing was performed for molecular typing.

Results

All isolates studied were non-typeable H. influenzae (NTHi). Most patients originated from the pediatrics department (78.6%, 154/196), and suffered from lung with respiratory tract infection (pneumonia and bronchitis, 68.4%, 134/196). The resistance rates of ampicillin, cefaclor and azithromycin were 71.4% (140/196), 36.7% (72/196) and 34.2% (67/196), respectively. 40.3% (79/196) of strains were β-lactamase positive ampicillin-resistant (BLPAR). All BLPAR carried the TEM-1 gene. 9.2% (18/196) were β-lactamase negative ampicillin-resistant strains (BLNAR). The PBP3 mutation was detected in the ampicillin-resistant strains (n = 113), of which 18 belonged to group IIa. A total of 49 sequence types (ST) and 23 clonal complexes (CC) were detected, among which CC107 (ST107, n = 27; ST1002, n = 5; ST1218, n = 5) was the most frequent clonal complexes. BLPAR isolates mostly belonged to ST107 (20/79), while BLNAR was predominantly distributed in ST12 (5/18).

Conclusion

H. influenzae infections are predominately caused by genetically diverse NTHi among hospitalized patients in Guiyang. The prevalence of β-lactamase production and PBP3 mutation may contribute to the high local ampicillin resistance rate.

Immunoinformatics design of multi-epitope peptide-based vaccine against Haemophilus influenzae strain using cell division protein

Haemophilus influenzae is a pathogen that causes invasive bacterial infections in humans. The highest prevalence lies in both young children and adults. Generally, there are no vaccines available that target all the strains of Haemophilus influenzae. Hence, the purpose of this research is to employ bioinformatics and immunoinformatics approaches to design a Multi-Epitope Vaccine candidate employing the pathogenic cell division protein FtsN that specifically combat all the Haemophilus influenzae strains. The current research focuses on developing subunit vaccine in contrast to vaccines generated from the entire pathogen. This will be accomplished by combining multiple bioinformatics and immunoinformatics approaches. As a result, prospective T cells (helper T lymphocyte and cytotoxic T lymphocytes) and B cells epitopes were investigated. The human leukocyte antigen allele having strong associations with the antigenic and overlapping epitopes were chosen, with 70% of the total coverage of the world population. To construct a linked vaccine design, multiple linkers were used. To increase the immunogenic profile, an adjuvant was linked using EAAAK linker. The final vaccine construct with 149 amino acids was obtained after adjuvants and linkers were added. The developed Multi-Epitope Vaccine has a high antigenicity as well as viable physiochemical features. The 3D conformation was modeled and undergoes refinement and validation using bioinformatics methods. Furthermore, protein-protein molecular docking analysis was performed to predict the effective binding poses of Multi-Epitope Vaccine with the Toll-like receptor 4 protein. Besides, vaccine underwent the codon translational optimization and computational cloning to verify the reliability and proper Multi-Epitope Vaccine expression. In addition, it is necessary to conduct experiments and research in the laboratory to demonstrate that the vaccine that has been developed is immunogenic and protective.

Antimicrobial resistance of Haemophilus influenzae isolates from pediatric hospitals in Mainland China: Report from the ISPED program, 2017-2019

PURPOSE

This study set out to determine the antimicrobial resistance trends of Haemophilus influenzae isolates from pediatric hospitals in Mainland China, which would provide basis for clinical treatment.

METHODS

The Infectious Disease Surveillance of Pediatrics (ISPED) collaboration group conducted this study. H. influenzae strains isolated from nine pediatric hospitals in Mainland China were included. Disk diffusion method was used for antimicrobial susceptibility test. Cefinase disc was used for detection of β-lactamase.

RESULTS

In total, 13810 H. influenzae isolates were included during 2017-2019: 93.17% of which were from respiratory tract specimens, 4.63% from vaginal swabs, 1.10% from secretion, and 1.10% from others. Of all strains, 63.32% isolates produced β-lactamase; 8.22% isolates were β-lactamase-negative and ampicillin-resistant (BLNAR). The resistance to sulfamethoxazole-trimethoprim was 70.98%, followed by resistance to ampicillin (69.37%), cefuroxime (51.35%), ampicillin-sulbactam (38.82%), azithromycin (38.21%), amoxicillin-clavulanate (35.28%). More than 90% of H. influenzae isolates were susceptible to ceftriaxone, cefotaxime, meropenem, levofloxacin and chloramphenicol. The resistance rate of ampicillin and azithromycin in H. influenzae showed an increasing trend through the years. Statistically significant differences in antibiotic-resistance rates of all the antibiotics except chloramphenicol were found in different regions. The major Multi-Drug Resistance pattern was resistant to β-lactams, macrolides, and sulfonamides.

CONCLUSIONS

There is a rising trend of resistance rate of ampicillin and azithromycin in H. influenzae. Antimicrobial resistance of H. influenzae deserves our ongoing attention. Third-generation cephalosporin could be the preferred treatment option of infections caused by ampicillin-resistant H. influenzae.

Microbial contamination profile change over a 4-year period in nonoperated cleft soft palate

AIMS

Surgical site infection is a major concern in cleft soft palate. Knowledge of the type, number and antimicrobial resistance of pathogens present preoperatively contribute to treatment success. The aim of this study is to determine whether or not the microbial contamination (diversity) preoperatively has changed since 2015.

METHODS AND RESULTS

Swabs were taken from the surgical site in 103 consecutive patients who presented for primary repair of the soft palate cleft. These were sent for microscopy, culture and sensitivity testing. Swabs were taken before disinfecting the site. Results were tabled and compared with two previous studies from the same facility. Out of 103 patients, 100 patients showed positive cultures with 42 different pathogenic micro-organisms identified. Most dominant pathogen was Klebsiella pneumoniae, 45.6%, increased by 28% from the previous two studies, with 93.6% of these pathogens resistant to one or more antimicrobials. Most of the other identified pathogens showed an alarming increase in occurrence, with a wide resistance to antimicrobials.

CONCLUSIONS

The increase in number and diversity of microbial contamination as well as their resistance to antimicrobials is a real concern. Ways of preventing postoperative infection in a natural way need to be explored.

SIGNIFICANCE

Surgeons need to be aware of constant changes in micro-organisms.

Bioprocessing and integration of a high flux screening systematic platform based on isothermal amplification for the detection on 8 common pathogens

During a large variety of common pathogens, E. coli, P. aeruginosa, MRSA, MRCNS, V. parahaemolyticus, L. monocytogenes and Salmonella are the leading pathogens responsible for large number of human infections and diseases. In this study, a high flux screening based on nucleic acid isothermal amplification technique has been developed. For the 8 common pathogens, species-specific targets had been selected and analyzed for their unique specificity. After optimization, separate LAMP reaction assays had been bioprocessed and integrated into one systematic detection platform, including 8 strips (PCR tubes) and 96-well plates. Eight standard strains verified for the accuracy. Application of the established high flux screening platform was used for detection for 48 samples in 4 different 96-well plates, with 2 groups of 2 operators using double-blind procedure. The accuracy of 100% was obtained, with the total time consumption as 66-75 min (for 12 samples detection on 8 different pathogens). As concluded, through the bioprocess of the systematic platform based on LAMP technique, it's been demonstrated to be capable of simultaneous detection of 8 pathogens, with high sensitivity, specificity, rapidity and convenience.

"One-step" characterization platform for pathogenic genetics of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is an important human pathogen causing a variety of life-threatening diseases. In recent years, the health problem caused by S. aureus contaminated food has become a global health problem. S. aureus can express various pathogenic factors, mainly used for adhesion, colonization, invasion and infection of the host. Therefore, rapid and accurate detection of virulence genes in S. aureus is necessary to prevent outbreaks caused by this pathogen. PCR is a useful tool for rapid detection of foodborne pathogens. The objective of this study was to detect the presence of major toxin genes in S. aureus, including sea, seb, sec, see, pvl and tsst, by using a PCR plate. Of the 13 strains tested, 12 (92.3%) were found to be positive for one or more toxin genes. This study realized the one-step detection of main toxin factors in S. aureus.

Emergence of Haemophilus influenzae with low susceptibility to quinolones isolated from pediatric patients in Japan

INTRODUCTION

In 2010, oral fluoroquinolone tosufloxacin (TFX) granules were released as the first oral respiratory quinolone for children in Japan.

METHODS

To investigate the recent trend of H. influenzae strains with low susceptibility to quinolones in children, we analyzed the gene sequences of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC, and parE of 23 clinical isolates from 15 patients aged <15 years with an MIC of ≥0.5 μg/mL for TFX from 2010 to 2018.

RESULTS

Amino acid substitutions were observed in both GyrA and ParC in 13 strains (81%, 13/16), except two strains with a TFX MIC of 0.5 μg/mL with amino acid substitution in only GyrA and one strain with a TFX MIC of 1 μg/mL with no amino acid substitution. Four ST422 strains were observed in 2018, the detection age range was wide (0-7 years), and the residential city was varied. A total of 3/15 patients had a clear history of TFX treatment.

CONCLUSIONS

Even for the strain with an MIC of 0.5 μg/mL for TFX, it is highly possible that it harbors a mutation in gyrA, which is the first step toward quinolone resistance, and it may also harbor mutations in both gyrA and parC. Furthermore, several specific sequence type quinolone-resistant H. influenzae strains, particularly ST422, may be widespread among children in Japan. It is necessary to investigate changes in resistance both at the MIC and gene levels. The continuous monitoring of strains and the use of antimicrobial drugs in treatment should be carefully observed.

Molecular Epidemiology and Antimicrobial Resistance of Haemophilus influenzae in Adult Patients in Shanghai, China

Background: The serotype and antimicrobial resistance of Haemophilus influenzae in adult patients have changed due to the application of antimicrobials and H. influenzae type b (Hib) vaccine worldwide. However, the epidemiologic characteristics of H. influenzae in Shanghai are still unavailable.

Objective: To determine the serotype distribution, antimicrobial resistance and multilocus sequence type (MLST) of H. influenzae in adult patients in Shanghai.

Methods: A total of 51 clinical isolates from adult patients were consecutively collected. Serotypes were determined according to specific capsule gene, bexA, amplified by PCR. Antimicrobial susceptibility test was carried out by the broth microdilution method. β-lactamase production was detected by cefinase disk and the ftsI gene were amplified and sequenced to determine the penicillin binding protein 3 (PBP3) mutation. Molecular epidemiology was performed by MLST analyses.

Results: All isolates studied were nontypeable H. influenzae (NTHi) and three of them (5.88%) caused invasive infection. The resistant rates of ampicillin and trimethoprim/sulfamethoxazole were both 45.10%. One third of these isolates produced TEM-1 type β-lactamase and 11.76% were β-lactamase negative ampicillin resistant strains (BLNAR). The PBP3 mutation was detected in 74.51% of the isolates, of which 12 belonged to group III. A total of 36 sequence types (STs) were identified among all isolates. Four isolates of ST103 (7.84%) all produced β-lactamase without mutation of PBP3.

Conclusion:H. influenzae infections among adults in Shanghai are predominately caused by NTHi with genetic diversity among adult patients. The prevalence of both β-lactamase production and PBP3 mutation may contribute to high ampicillin resistance rate in Shanghai.

Antibiotic-Resistant Community-Acquired Bacterial Pneumonia

Antimicrobial resistance is a global concern, and prudent use of antibiotics is essential to preserve the current armamentarium of effective drugs. Acute respiratory tract infection is the most common reason for antibiotic prescription in adults. In particular, community-acquired pneumonia poses a significant health challenge and economic burden globally, especially in the current landscape of a dense and aging population. By updating the knowledge on the common antimicrobial-resistant pathogens in community-acquired respiratory tract infections, their prevalence, and resistance may pave the way to enhancing appropriate antibiotic use in the ambulatory and health care setting.