Moraxella Catarrhalis Strains Research Articles

Polyurethane degradation by extracellular urethanase producing bacterial isolate Moraxella catarrhalis strain BMPPS3

Plastic waste has become a global issue and a threat to the ecosystem. The present study isolated polyurethane (PU) degrading bacterial species from soil dumped with plastic wastes. Four bacterial isolates, RS1, RS6, RS9 and RS13 were obtained and their ability to degrade PU in a synthetic medium with PU as a sole source of carbon was assessed individually. After thirty days of incubation, the highest PU weight loss of 67.36 ± 0.32% was recorded in the medium containing RS13 isolate. The results of FTIR revealed the occurrence of carbonyl peaks. The putative isolate RS13 confirmed with the genus Moraxella according to 16S rRNA gene sequencing and the isolate was specified as Moraxella catarrhalis strain BMPPS3. The restriction analysis of Moraxella catarrhalis strain BMPPS3 revealed that the GCAT content to 51% and 49% correspondingly. Moraxella catarrhalis strain BMPPS3 was able to colonize on PU surface and form a biofilm as revealed by SEM investigation. Fatty acids and alkanes were found to be the degradation products by GC-MS analysis. The presence of these metabolites facilitated the growth of strain RS13 and suggested that ester hydrolysis products had been mineralized into CO2 and H2O. Extracellular biosurfactant synthesis has also been found in Moraxella catarrhalis strain BMPPS13 inoculated with synthetic media and mineral salt media containing PU and glucose as carbon sources, respectively with a significant level of cell-surface hydrophobicity (32%). The production and activity of extracellular esterase showed consistent increase from day 1–15 which peaked (1.029 mM/min/mg) on day 24 significantly at P < 0.001. Crude biosurfactants were lipopeptide-based, according to the characteristic investigation. According to this study findings, Moraxella catarrhalis produces biosurfactants of the esterase, urethanase and lipase (lipopeptide) types when carbon source PU is present.

An integrated complete-genome sequencing and systems biology approach to predict antimicrobial resistance genes in the virulent bacterial strains of Moraxella catarrhalis.

Moraxella catarrhalis is a symbiotic as well as mucosal infection-causing bacterium unique to humans. Currently, it is considered as one of the leading factors of acute middle ear infection in children. As M. catarrhalis is resistant to multiple drugs, the treatment is unsuccessful; therefore, innovative and forward-thinking approaches are required to combat the problem of antimicrobial resistance (AMR). To better comprehend the numerous processes that lead to antibiotic resistance in M. catarrhalis, we have adopted a computational method in this study. From the NCBI-Genome database, we investigated 12 strains of M. catarrhalis. We explored the interaction network comprising 74 antimicrobial-resistant genes found by analyzing M. catarrhalis bacterial strains. Moreover, to elucidate the molecular mechanism of the AMR system, clustering and the functional enrichment analysis were assessed employing AMR gene interactions networks. According to the findings of our assessment, the majority of the genes in the network were involved in antibiotic inactivation; antibiotic target replacement, alteration and antibiotic efflux pump processes. They exhibit resistance to several antibiotics, such as isoniazid, ethionamide, cycloserine, fosfomycin, triclosan, etc. Additionally, rpoB, atpA, fusA, groEL and rpoL have the highest frequency of relevant interactors in the interaction network and are therefore regarded as the hub nodes. These genes can be exploited to create novel medications by serving as possible therapeutic targets. Finally, we believe that our findings could be useful to advance knowledge of the AMR system present in M. catarrhalis.

Оценка антибиотикочувствительности штаммов Moraxella catarrhalis, выделенных от пациентов с осложненным течением острых респираторных вирусных инфекций и других острых респираторных заболеваний

In recent years, acute respiratory viral infections (ARVIs) and other acute respiratory diseases (ARDs) have acquired some new characteristics of the disease course. The structure of complications has changed, in particular, such complications as community-acquired pneumonia (CAP) and lesions to the upper respiratory tract have become significantly more common. CAP remains one of the main causes of death in patients with ARVIs and other acute respiratory infections due to bacterial resistance to antibiotics. Objective. To assess drug sensitivity of Moraxella catarrhalis strains isolated from patients with complicated ARVIs or ARDs. Materials and methods. Drug susceptibility assessment was performed using the disk diffusion method (DDM) and gradient diffusion method (E-test). The production of β-lactamases was evaluated using nitrocephine, a chromogenic substrate. Results. Isolated strains of M. catarrhalis were resistant to third-generation cephalosporins and sensitive to fourth- and fifthgeneration cephalosporins. More than 70% of M. catarrhalis strains developed resistance to macrolides; 8% of strains were resistant to amoxiclav. All isolated M. catarrhalis strains were sensitive to respiratory fluoroquinolones, carbapenems, and ampicillin-sulbactam. Key words: Moraxella catarrhalis, complications of acute viral infections, bacterial sensitivity to antibiotics

Pneumococcal carriage among children aged 4 – 12 years in Angola 4 years after the introduction of a pneumococcal conjugate vaccine

Children in Angola are affected by a high burden of disease caused by pneumococcal infections. The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the childhood immunization programme in 2013 but the serotype distribution of Streptococcus pneumoniae and antimicrobial susceptibility patterns are unknown. We did a cross-sectional nasopharyngeal carriage study in Luanda and Saurimo, Angola (PCV13 3rd dose coverage 67% and 84%, respectively) during November to December 2017 comprising 940 children aged 4–12 years. The main objective was to assess vaccine serotype coverage and antimicrobial susceptibility rates for S. pneumoniae. Our secondary aim was to characterize colonizinig strains of Haemophilus influenzae and Moraxella catarrhalis. Pneumococcal colonization was found in 35% (95% CI 32–39%) of children (n = 332), with 41% of serotypes covered by PCV13. The most common serotypes were 3 (8%), 18C (6%), 23F (6%), 11A (6%), 34 (6%), 19F (5%) and 16 (5%). Carriage of H. influenzae and M. catarrhalis was detected in 13% (95% CI 11–15%) and 15% (95% CI 13–17%) of children, respectively. Non-susceptibility to penicillin was common among pneumococci (40%), particularly among PCV13-included serotypes (50% vs. 33%; p = 0.003), although the median minimal inhibitory concentration was low (0.19 µg/mL, IQR 0.13–0.25 µg/mL). Most pneumococci and H. influenzae were susceptible to amoxicillin (99% and 88%, respectively). Furthermore, resistance to trimethoprim-sulfamethoxazole was>70% among all three species. Multidrug-resistant pneumococci (non-susceptible to ≥ 3 antibiotics; 7% [n = 24]) were further studied with whole genome sequencing to investigate clonality as an underlying cause for this phenotype. No clearly dominating clone(s) were, however, detected. The results indicate that continued use of PCV13 may have positive direct and herd effects on pneumococcal infections in Angola as carriage of vaccine serotypes was common in the non-vaccinated age group. Finally, amoxicillin is assessed to be a feasible empirical treatment of respiratory tract infections in Angola.

Surveillance on susceptibility of strains isolated from pediatric infections.

During the period from January to December 2015, 104 Streptococcus pneumoniae strains, 129 Haemophilus influenzae strains and 54 Moraxella catarrhalis strains isolated from clinical specimens of pediatric infections in the national 16 institutions, studied susceptibilities of total 28 antibiotics, the capsular serotype for S.pneumoniae, the capsular b type and β-lactamase production capability for H.influenzae, and the β-lactamase production capability for M.catarrhalis were measured. In S.pneumoniae, the results showed that 68 strains (65.4%) were PSSP, 32 (30.8%) were PISP, and 4 (3.8%) were PRSP. The susceptibilities of TBPM and GRNX among oral antibiotics, and PAPM among injectable antibiotics demonstrated the lowest value with MIC90≤0.06μg/mL. The most frequent distribution of S.pneumoniae serotypes was seen in 15B, followed by 19A, and 35B. Serotype strains contained in 13-valent pneumococcal conjugate vaccine (PCV13) were 19 strains (18.3%). In H.influenzae, the results showed that BLNAS accounted for 40 strains (31.0%), BLNAI for 28 strains (21.7%), BLNAR for 47 strains (36.4%), β-lactamase producing for 14 strains (10.8%). The susceptibilities of quinolones demonstrated the lowest outcome among oral antibiotics with MIC90≤0.06μg/mL, and CTRX and TAZ/PIPC (TAZ4 fixed) among injectable antibiotics with MIC of 0.25μg/mL. There was no detection of capsular type b strains. In M.catarrhalis, all the isolates were β-lactamase producing strains. The susceptibilities of TBPM, CPFX, TFLX and GRNX among oral antibiotics, and TAZ/PIPC (TAZ4 fixed), PAPM, MEPM and DRPM among injectable antibiotics demonstrated the lowest outcome with MIC of ≤0.06μg/mL.

Persistence of Moraxella catarrhalis in Chronic Obstructive Pulmonary Disease and Regulation of the Hag/MID Adhesin.

Persistence of bacterial pathogens in the airways has profound consequences on the course and pathogenesis of chronic obstructive pulmonary disease (COPD). Patients with COPD continuously acquire and clear strains of Moraxella catarrhalis, a major pathogen in COPD. Some strains are cleared quickly and some persist for months to years. The mechanism of the variability in duration of persistence is unknown. Guided by genome sequences of selected strains, we studied the expression of Hag/MID, hag/mid gene sequences, adherence to human cells, and autoaggregation in longitudinally collected strains of M. catarrhalis from adults with COPD. Twenty-eight of 30 cleared strains of M. catarrhalis expressed Hag/MID whereas 17 of 30 persistent strains expressed Hag/MID upon acquisition by patients. All persistent strains ceased expression of Hag/MID during persistence. Expression of Hag/MID in human airways was regulated by slipped-strand mispairing. Virulence-associated phenotypes (adherence to human respiratory epithelial cells and autoaggregation) paralleled Hag/MID expression in airway isolates. Most strains of M. catarrhalis express Hag/MID upon acquisition by adults with COPD and all persistent strains shut off expression during persistence. These observations suggest that Hag/MID is important for initial colonization by M. catarrhalis and that cessation of expression facilitates persistence in COPD airways.

Novel mechanism responsible for high-level macrolide resistance in Moraxella catarrhalis.

BackgroundHigh-level macrolide-resistant Moraxella catarrhalis strains have been isolated; however, the underlying mechanism has not been well elucidated. We investigated the role of mutations in the 23S rRNA gene and the L4 and L22 ribosomal proteins using spontaneous erythromycin-resistant mutants and transformants.Materials and methodsThe erythromycin-susceptible M. catarrhalis ATCC25238 and clinical isolate Mc19 were used as parental strains. To obtain spontaneous erythromycin-resistant mutants, in vitro stepwise selection was performed using brain–heart infusion agar plates containing various concentrations of erythromycin. The role of the mutations identified in the spontaneous mutants was validated using transformation experiments.ResultsWe obtained two spontaneous mutants with high-level resistance to erythromycin, S25-32-af10 and S19-256-af10, from ATCC25238 and Mc19, respectively. S25-32-af10 exhibited mutations of Q61R in L4 and Insertion98SRADRIS in L22. S19-256-af10 exhibited three C2611T-mutated alleles in the 23S rRNA gene and G65A in L4. Transformants with single mutations identified in S25-32-af10 or S19-256-af10 showed higher erythromycin and azithromycin minimum inhibitory concentrations (MICs) than those of each parental strain. However, transformants with multiple mutations identified in S25-32-af10 or S19-256-af10 showed macrolide MICs similar to those of each parental strain.ConclusionOur results provide the first evidence suggesting that Q61R in L4 and Insertion98SRADRIS in L22 are involved in the synergistic acquisition of high-level resistance to both 14- and 15-member macrolides, and that C2611T in the 23S rRNA gene and G65A in L4 also synergistically contribute toward conferring high-level 14-member macrolide resistance to M. catarrhalis.

Alternations in DNA gyrase genes in low-level fluoroquinolone-resistant Moraxella catarrhalis strains isolated in Poland.

PurposeThe purpose of this study was to investigate the molecular mechanisms of fluoroquinolone resistance in Moraxella catarrhalis clinical strains isolated in Lublin, Poland.Materials and methodsA total of 150 non-duplicate clinical strains of M. catarrhalis were obtained from individuals with signs of upper respiratory tract infection. Bacterial identification was corroborated on the basis of phenotypic and biochemical characteristics as well as with the use of molecular tests. The antimicrobial susceptibility of M. catarrhalis isolates was determined using the disk diffusion method and Etest. Mutations in the gyrase (gyrA and gyrB) and topoisomerase (parC and parE) genes were determined by polymerase chain reaction and sequencing.ResultsIt was observed that 16.7% of the studied isolates were drug resistant. Resistance to tetracycline was detected for 12% of the strains. Resistance to nalidixic acid, moxifloxacin, and levofloxacin was exhibited by 2.7% of the strains; 1.3% of the strains were resistant to trimethoprim/sulfamethoxazole and 0.7% to erythromycin. Minimum inhibitory concentration values of the four strains demonstrating fluoroquinolone resistance were: 6–12 mg/L for nalidixic acid, 1–1.5 mg/L for levofloxacin, 1 mg/L for moxifloxacin, and 0.25–0.5 mg/L for ciprofloxacin. The research resulted in the detection of mutations in 4 strains, in gyrase gyrA and gyrB genes. In gyrA gene, there occurred mutation G412C as well as four silent transition mutations. Within gyrB gene, there occurred mutation, substitution A1481G, as well as two identical silent mutations.ConclusionOur findings reveal that resistance to fluoroquinolones in M. catarrhalis is connected with amino acid substitutions in gyrA and gyrB genes. To our knowledge, this work is the first description of fluoroquinolone-resistant clinical strains of M. catarrhalis with described mutations in gyrA and gyrB genes isolated in Poland and in Europe.

Design of mononuclear, binuclear and polynuclear molybdenum(VI) complexes based on ONO benzoylacetone derived enaminones and their in vitro biological activity

Molybdenum(VI) complexes of different nuclearity, mononuclear, [MoO2(L1 or 2)(MeOH)]·MeOH (1·MeOH and 2·MeOH), [MoO2(L1 or 2)(D)] [D = pyridine, (1a and 2a), 3-methylpyridine, (1b and 2b) and 4-methylpyridine, (1c and 2c)], binuclear [{MoO2(L1 or 2)}2(D)] (D = 4,4′-bipyridine (1d, 1d′ and 2d), and polynuclear complexes [MoO2(L1 or 2)]n (3 and 4) were synthesized by solution based reactions of enaminones (H2L1 = 3-(2-hydroxy-4-methylphenylamino)-1-phenylbut-2-en-1-one; H2L2 = 3-(2-hydroxy-5-methylphenylamino)-1-phenylbut-2-en-1-one) with the dioxobis(acetylacetonato)molybdenum(VI) complex, [MoO2(acac)2]. Reactions of the mononuclear complexes 1·MeOH and 2·MeOH with pyridine and its derivatives resulted in corresponding mononuclear [MoO2(L1 or 2)(D)] or binuclear [{MoO2(L1 or 2)}2(D)] complexes. In case of [{MoO2(L1)}2(4,4-bpy)] two polymorphic forms are obtained (1d and 1d′). The cross-linked transformations of [MoO2(L1 or 2)(D)] complexes in solution or when exposed to vapors of N-heterocyclic bases have been explored. Crystal and molecular structures of ten complexes (1·MeOH, 2·MeOH, 1a–d, 1d′, 2b–d) were determined by the single-crystal X-ray diffraction analysis. Enaminone ligands and their molybdenum complexes were characterized by elemental and TG analysis, IR and NMR spectroscopy and screened for their in vitro cytotoxic and antibacterial activities. None of the tested compounds showed cytotoxic ability against THP-1 and HepG2 cell lines. Compounds 1·MeOH, 1b, 2·MeOH, 2a and 3, exhibited weak antibacterial activity on Moraxella catarrhalis strain while other complexes did not show antibacterial properties towards Staphylococcus aureus, Enterococcus faecalis and Escherichia coli bacteria.

Inhibitory effect of streptococci on the growth of M. catarrhalis strains and the diversity of putative bacteriocin-like gene loci in the genomes of S. pneumoniae and its relatives

S. pneumoniae is a facultative human pathogen causing a wide range of infections including the life-threatening pneumoniae or meningitis. It colonizes nasopharynx as well as its closest phylogenetic relatives S. pseudopneumoniae and S. mitis. Both the latter, despite the considerable morphological and phenotypic similarity with the pneumococcus, are considerably less pathogenic for humans and cause infections mainly in the immunocompromized hosts. In this work, we compared the inhibitory effect of S. pneumoniae and its relatives on the growth of Moraxella catarrhalis strains using the culture-based antagonistic test. We observed that the inhibitory effect of S. mitis strains is kept when a hydrogen peroxide produced by cells is inactivated by catalase, and even when the live cells are killed in chloroform vapors, in contrast to the pneumococcus whose inhibiting ability disappeared when the cells die. It was suggested that this effect may be due to the production of bacterial antimicrobial peptides by S. mitis, so we examined the genomes of our strains for the presence of bacteriocin-like peptides encoding genes. We observed that a set of bacteriocin-like genes in the genome of S. mitis is greatly poorer in comparison with S. pneumoniae one; moreover, in one S. mitis strain we found no bacteriocin-like genes. It could mean that there are probably some additional opportunities of S. mitis to inhibit the growth of competing neighbors which are still have to be discovered.

Multilocus sequence typing-based analysis of Moraxella catarrhalis population structure reveals clonal spreading of drug-resistant strains isolated from childhood pneumonia

This work revealed the drug resistance and population structure of Moraxella catarrhalis strains isolated from children less than three years old with pneumonia. Forty-four independent M. catarrhalis strains were analyzed using broth dilution antimicrobial susceptibility testing and multilocus sequence typing (MLST). The highest non-susceptibility rate was observed for amoxicillin (AMX), which reached 95.5%, followed by clindamycin (CLI) (n=33; 75.0%), azithromycin (AZM) (61.4%), cefaclor (CEC) (25.0%), trimethoprim-sulfamethoxazole (SXT) (15.9%), cefuroxime (CXM) (4.5%), tetracycline (TE) (2.3%), and doxycycline (DOX) (2.3%). There was no strain showing non-susceptibility to other six antimicrobials. Using MLST, the 44 M. catarrhalis strains were divided into 33 sequence types (STs). Based on their allelic profiles, the 33 STs were divided into one CC (CC363) and 28 singletons. CC363 contained five STs and ST363 was the founder ST. CC363 contained 63.6%, 33.3%, and 40.7% of CEC non-susceptible, CLI non-susceptible and AZM non-susceptible strains, respectively. The proportions of CEC non-susceptible, CLI non-susceptible and AZM non-susceptible strains in CC363 were higher than that of singletons; these differences were significant for CEC (p=0.002) and AZM (p=0.011). Furthermore, CC363 contained more AMX-CLI-AZM co-non-susceptible and AMX-CEC-CLI-AZM co-non-susceptible strains than the singletons (p=0.007 and p<0.001, respectively). CC363 is a drug-resistant clone of clinical M. catarrhalis strains in China. Expansion of this clone under selective pressure of antibiotics should be noted and long-term monitoring should be established.

A Genoproteomic Approach to Detect Peptide Markers of Bacterial Respiratory Pathogens.

Rapid identification of respiratory pathogens may facilitate targeted antimicrobial therapy. Direct identification of bacteria in bronchoalveolar lavage (BAL) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry is confounded by interfering substances. We describe a method to identify unique peptide markers of 5 gram-negative bacteria by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for direct pathogen identification in BAL. In silico translation and digestion were performed on 14-25 whole genomes representing strains of Acinetobacter baumannii, Moraxella catarrhalis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Klebsiella pneumoniae. Peptides constituting theoretical core peptidomes in each were identified. Rapid tryptic digestion was performed; peptides were analyzed by LC-MS/MS and compared with the theoretical core peptidomes. High-confidence core peptides (false discovery rate <1%) were identified and analyzed with the lowest common ancestor search to yield potential species-specific peptide markers. The species specificity of each peptide was verified with protein BLAST. Further, 1 or 2 pathogens were serially diluted into pooled inflamed BAL, and a targeted LC-MS/MS assay was used to detect 25 peptides simultaneously. Five unique peptides with the highest abundance for each pathogen distinguished these pathogens with varied detection sensitivities. Peptide markers for A. baumannii and P. aeruginosa, when spiked simultaneously into inflamed BAL, were detected with as few as 3.6 (0.2) × 103 and 2.2 (0.6) × 103 colony-forming units, respectively, by targeted LC-MS/MS. This proof-of-concept study shows the feasibility of identifying unique peptides in BAL for 5 gram-negative bacterial pathogens, and it may provide a novel approach for rapid direct identification of bacterial pathogens in BAL.

Bacterial-resistance among outpatients of county hospitals in China: significant geographic distinctions and minor differences between central cities

The purpose of this study was to survey antibacterial resistance in outpatients of Chinese county hospitals. A total of 31 county hospitals were selected and samples continuously collected from August 2010 to August 2011. Drug sensitivity testing was conducted in a central laboratory. A total of 2946 unique isolates were collected, including 634 strains of Escherichia coli, 606 Klebsiella pneumoniae, 476 Staphylococcus aureus, 308 Streptococcus pneumoniae, and 160 Haemophilus influenzae. Extended-spectrum β-lactamases were detected in E. coli (42.3% strains), K. pneumoniae (31.7%), and Proteus mirabilis (39.0%). Ciprofloxacin-resistance was detected in 51.0% of E. coli strains. Salmonella spp. and Shigella spp. were sensitive to most antibacterial agents. Less than 8.0% of Pseudomonas aeruginosa isolates were resistant to carbapenem. For S. aureus strains, 15.3% were resistant to methicillin, and some strains of S. pneumoniae showed resistance to penicillin (1.6%), ceftriaxone (13.0%), and erythromycin (96.4%). β-lactamase was produced by 96.5% of Moraxella catarrhalis strains, and 36.2% of H. influenzae isolates were resistant to ampicillin. Azithromycin-resistant H. influenzae, imipenem-resistant but meropenem-sensitive Proteus, and ceftriaxone- and carbapenem non-sensitive M. catarrhalis were recorded. In conclusion, cephalosporin- and quinolone-resistant strains of E. coli and Klebsiella pneumonia and macrolide-resistant Gram-positive cocci were relatively prominent in county hospitals. The antibacterial resistance profiles of isolates from different geographical locations varied significantly, with proportions in county hospitals lower than those in their tertiary counterparts in the central cities, although the difference is diminishing.

Antibodies against outer membrane proteins of Moraxella catarrhalis and nontypeable Haemophilus influenzae cross-react with various pathogens of human respiratory tract

Event Abstract Back to Event Antibodies against outer membrane proteins of Moraxella catarrhalis and nontypeable Haemophilus influenzae cross-react with various pathogens of human respiratory tract Daria Augustyniak1*, Joanna Bonarowska1, Paweł Mackiewicz2 and Zuzanna Drulis-Kawa1 1 University of Wroclaw, Department of Pathogen Biology and Immunology, Institute of Genetics and Microbiology, Poland 2 University of Wroclaw, Department of Genomics, Faculty of Biotechnology, , Poland Introduction: Moraxella catarrhalis and nontypaeble Haemophilus influenzae are important, human-restricted respiratory tract pathogens [1,2]. Outer membrane proteins (OMPs) of these bacteria are their most immunogenic antigens and targets for the host immune response [3,4]. The goal of the study was to quantitatively and qualitatively assess the reactivity of anti-OMPs antibodies against cross-reactive and surface-exposed epitopes of other important pathogens of human respiratory tract. Materials and Methods: Antisera were obtained from six groups of mice, each immunized with OMPs isolated from different Moraxella catarrhalis strains (anti-OMPMc sera) or nontypeable Haemophilus influenzae strains (anti-OMPNTHi sera). OMPs were isolated using Zwittergent 3-14 procedure [4]. The titers of cross-reactive antibodies were measured by whole-cell ELISA whereas their specificities with bacterial OMPs was confirmed by Western-blot according to described methods [4]. The studied pathogens were: Pseudomonas aeruginosa including cystic fibrosis (CF) and non-cystic fibrosis (non-CF) strains, Burkholderia cepacia (CF), Acinetobacter baumanii, Haemophilus parainfluenzae and additionally Candida albicans. To find potential cross-reactive antigens and epitopes in these pathogens, we performed BLAST searches of their protein databases using as a query M. catarrhalis and H. influenzae OMPs for which immune reaction was proved. Results: We found statistically significant homologues especially to Moraxella OMP CopB, E and CD as well as to Haemophilus OMP P1, P4, D15 and Tbp1. Majority of the found homologues are peripheral or outer membrane proteins and could be involved in the cross immune reactions. In whole-cell ELISA we found cross-reactive epitopes in all studied pathogens of respiratory tract. We found that among analyzed anti-OMPMc and anti-OMPNTHi sera, the several were medium or highly cross-reactive. The cross-reactive titers in anti-OMPMc sera were in the range 1:200 – 1:1500 that was 500 – 1000-fold lower than titers for homologous strains. The cross-reactivity of anti-OMPNTHi sera were in the range 1:2000 – 1:11000 that was 4 – 20-fold lower than for homologous counterparts. The reactivity of some cross-reactive antibodies was confirmed with OMPs of tested strains. The differences in recognition of cross-reactive surface epitope between CF and non-CF strains were dependent on used antisera rather than particular strain. Within anti-OMPMc sera the weakest reactivity was usually detected for A. baumanii whereas the highest for C. albicans. In the case of anti-OMPNTHi sera the weakest reactivity was observed for C. albicans and the highest for H. parainfluenzae. The sera with greater cross-reactive potency were found within anti-OMPNTHi ones. Conclusion: The results indicate that IgG antibodies induced against OMPs of particular M.catarrhalis and H.influenzae recognize cross-reactive surface-exposed epitopes in multiple strains of respiratory pathogens. The biological role of this phenomenom is supposed to be confirm in antibody-dependent functional assays. The presence of cross-reactivity should be take under consideration in immunodiagnostic tests for respiratory pathogens.

Molecular detection of BRO β-lactamase gene of Moraxella catarrhalis isolated from Sudanese patients

Objective: To determine the frequency of BRO β-lactamase gene among Moraxella catarrhalis strains isolated from individuals with different clinical manifestations in Sudan. Design: Prospective cross-sectional laboratory-based study. Setting: Different hospitals and health centers in Khartoum State, Sudan. Materials and Methods: Fifteen (n = 15) β lactamase positive M. catarrhalis isolates, isolated from Sudanese patients with different clinical pictures were examined for the presence of BRO β-lactamase gene using restriction fragment length polymorphism (RFLP) technique. Results: Out of 400 patients, M. catarrhalis was isolated from 15 (3.75%) patients. All of the M. catarrhalis isolates were conϐirmed as β-lactamase producer, from which 11 isolates (73.3%) were positive for a BRO-1 gene using RFLP, whereas 4 isolates (23.7%) were BRO negative. Conclusion: The majority of β-lactamase gene of Moraxella catarrhalis in Sudan is BRO-1 gene. No BRO-2 gene was detected in this study; hence, the resistant phenomenon of Sudanese isolates of M. catarrhalis may attribute to BRO-1 gene.

Genome Analysis of Moraxella catarrhalis Strain RH4, a Human Respiratory Tract Pathogen

__AUTHOR'S CORRECTION__ Volume 192, no. 14, pages 3574–3583, 2010. The genome sequence described is that of strain BBH18, isolated from sputum, and not of strain RH4, which was isolated from blood. Consequently, the title should read “Genome Analysis of Moraxella catarrhalis Strain BBH18, a Human Respiratory Tract Pathogen,” and the strain name RH4 should be replaced by BBH18 throughout the manuscript. Furthermore, in the abstract (page 3574, line 4), introduction (page 3574, column 2, line 27), and Materials and Methods (page 3575, column 1, lines 13 and 14), the phrase “isolated from blood of an infected patient (14)” should be changed to “isolated from sputum of a patient with COPD during an exacerbation (45).” The correct reference for strain BBH18 is reference 45 (A. Mollenkvist et al., J. Bacteriol. 185:2285–2295, 2003).

Molecular mechanism of macrolide–lincosamide resistance in Moraxella catarrhalis

We identified a Moraxella catarrhalis strain with high-level resistance to azithromycin (MIC>256 mg l(-1)), NSH1, isolated from nasopharyngeal swab samples from an inpatient with acute bronchitis in a Japanese hospital in 2011 and determined its mechanism of macrolide-lincosamide resistance. Antimicrobial susceptibility of M. catarrhalis strains was determined using the Etest and agar dilution methods. Mutations in the four 23S rRNA alleles, the ribosomal proteins L4 and L22, and methylase genes erm(B) and erm(F) were tested by PCR and/or sequencing. The efflux system was examined using appropriate inhibitors. Transformation experiments were performed using DNA amplicons of the 23S rRNA gene of M. catarrhalis strain NSH1. This strain showed high-level resistance to erythromycin, clarithromycin, azithromycin, clindamycin (MICs>256 mg l(-1)) and josamycin (MIC = 128 mg l(-1)), and contained the A2058T mutation (Escherichia coli numbering) in four of the 23S rRNA alleles. Mutation of the ribosomal proteins and overproduction of the efflux system were not observed, and methylase genes were not detected. When amplified DNA containing the single A2058T mutation was transformed into M. catarrhalis strains, transformants with three A2058T-mutated 23S rRNA alleles showed high-level resistance to macrolide-lincosamide, similar to strain NSH1. In contrast, transformants with two A2058T-mutated 23S rRNA alleles showed low-level MICs (azithromycin: 0.38-0.5 mg l(-1)). Thus, a single A2058T mutation occurring in at least three 23S rRNA alleles confers high-level resistance to 14-, 15- and 16-membered macrolides and lincosamides in M. catarrhalis possessing four 23S rRNA alleles. This study represents the first evidence, to our knowledge, of this effect in M. catarrhalis.

Effects of Bacterial Infection on Airway Antimicrobial Peptides and Proteins in COPD

Pathogenic bacteria colonize the airways of 30% to 40% of patients with COPD and cause approximately 50% of exacerbations. New strains of nontypeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis are associated with exacerbations. Antimicrobial protein/peptides (AMPs) play important roles in innate lung defense against pathogens. To our knowledge, the changes in AMP baseline levels in respiratory secretions during bacterial colonization and exacerbation have not been described. The objective of this study was to elucidate the effects of the acquisition of a new strain of pathogenic bacteria on the airway levels of AMPs in patients with COPD. One hundred fifty-three samples from 11 patients were selected from COPD sputum samples collected prospectively over 6 years. Samples were grouped as culture-negative (no pathogenic bacteria), colonization, and exacerbation due to new strains of NTHI and M catarrhalis. Levels of lysozyme, lactoferrin, LL-37, and secretory leukocyte protease inhibitor (SLPI) were measured by enzyme-linked immunosorbent assay and compared among groups by paired analysis. Compared with baseline, sputum lysozyme levels were significantly lower during colonization and exacerbation by NTHI (P = .001 and P = .013, respectively) and M catarrhalis (P = .007 and P = .018, respectively); SLPI levels were lower with exacerbation due to NTHI and M catarrhalis (P = .002 and P = .004, respectively), and during colonization by M catarrhalis (P = 032). Lactoferrin levels did not change significantly; LL-37 levels were higher during exacerbation by NTHI and M catarrhalis (P = .001 and P = .018, respectively). Acquisition of NTHI and M catarrhalis is associated with significant changes in airway levels of AMPs, with larger changes in exacerbation. Airway AMP levels are likely to be important in pathogen clearance and clinical outcomes of infection in COPD.

Progress of Moraxella Catarrhalis

Moraxella Catarrhalis emerged as the third cause of respiratory tract infection in children.Over 90% of the Moraxella Catarrhalis strains isolated currently produced by β-lactamases positive.Moraxella Catarrhalis resist to Ampicillin because of the β-lactamases,such as the BRO-1 type,BRO-2 type and BRO-3 type.The BRO genes appeared to be located on the chromosome and be coded.Twenty-one new mutations were found in the putative promoter region of the BRO genes. Key words: Moraxella catarrhalis; Drug resistance; β-lactamases; BRO-gene

Outer membrane porin M35 of Moraxella catarrhalis mediates susceptibility to aminopenicillins

BackgroundThe outer membrane protein M35 is a conserved porin of type 1 strains of the respiratory pathogen Moraxella catarrhalis. It was previously shown that M35 is involved in the uptake of essential nutrients required for bacterial growth and for nasal colonization in mice. The aim of this study was (i) to characterize the potential roles of M35 in the host-pathogen interactions considering the known multifunctionality of porins and (ii) to characterize the degree of conservation in the phylogenetic older subpopulation (type 2) of M. catarrhalis.ResultsIsogenic m35 mutants of the type 1 strains O35E, 300 and 415 were tested for their antimicrobial susceptibility against 15 different agents. Differences in the MIC (Minimum Inhibitory Concentration) between wild-type and mutant strains were found for eight antibiotics. For ampicillin and amoxicillin, we observed a statistically significant 2.5 to 2.9-fold MIC increase (p < 0.03) in the m35 mutants. Immunoblot analysis demonstrated that human saliva contains anti-M35 IgA. Wild-type strains and their respective m35 mutants were indistinguishable with respect to the phenotypes of autoagglutination, serum resistance, iron acquisition from human lactoferrin, adherence to and invasion of respiratory tract epithelial cells, and proinflammatory stimulation of human monocytes. DNA sequencing of m35 from the phylogenetic subpopulation type 2 strain 287 revealed 94.2% and 92.8% identity on the DNA and amino acid levels, respectively, in comparison with type 1 strains.ConclusionThe increase in MIC for ampicillin and amoxicillin, respectively, in the M35-deficient mutants indicates that this porin affects the outer membrane permeability for aminopenicillins in a clinically relevant manner. The presence of IgA antibodies in healthy human donors indicates that M35 is expressed in vivo and recognized as a mucosal antigen by the human host. However, immunoblot analysis of human saliva suggests the possibility of antigenic variation of immunoreactive epitopes, which warrants further analysis before M35 can be considered a potential vaccine candidate.