Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases

The characterization of Moraxella catarrhalis carried in the general population

Moraxella catarrhalis is a common cause of respiratory tract infection, particularly otitis media in children, whilst it is also associated with the onset of exacerbation in chronic obstructive pulmonary disease in adults. Despite the need for an efficacious vaccine against M. catarrhalis, no candidates have progressed to clinical trial. This study, therefore, aimed to characterize the diversity of M. catarrhalis isolated from the upper respiratory tract of healthy children and adults, to gain a better understanding of the epidemiology of M. catarrhalis and the distribution of genes associated with virulence factors, to aid vaccine efforts. Isolates were sequenced and the presence of target genes reported. Contrary to prevailing data, this study found that lipooligosaccharide (LOS) B serotypes are not exclusively associated with 16S type 1. In addition, a particularly low prevalence of LOS B and high prevalence of LOS C serotypes was observed. M. catarrhalis isolates showed low prevalence of antimicrobial resistance and a high gene prevalence for a number of the target genes investigated: ompB2 (also known as copB), ompCD, ompE, ompG1a, ompG1b, mid (also known as hag), mcaP, m35, tbpA, lbpA, tbpB, lbpB, msp22, msp75 and msp78, afeA, pilA, pilQ, pilT, mod, oppA, sbp2, mcmA and mclS.

Moraxella Keratitis: A Case Series

OBJECTIVE

To report the ocular and systemic risk factors, clinical manifestations, and management outcomes of Moraxella keratitis.

METHODS

This retrospective study included patients with culture-proven Moraxella keratitis in South Texas between 2012 and 2018. Clinical data including demographics, ocular and systemic risk factors, clinical presentation, speciation, and treatment course were collected.

RESULTS

Fourteen eyes of 14 patients had culture-proven Moraxella keratitis which made up 8.1% of cases of culture-proven bacterial keratitis in the period studied. These included 10 men and 4 women with a mean age of 52.7±11.3 years. Ten patients (71.4%) had different ocular risk factors such as ocular trauma, corneal foreign body, contact lens use, preceding viral keratitis, neurotrophic cornea, and recent corneal transplant on topical steroids. Systemic risk factors included diabetes mellitus, systemic immunosuppressive therapy, cancer chemotherapy, and AIDS. There was no specific clinical manifestation. The size of stromal infiltration on initial presentation varied among the cases, with 71.4% stromal infiltrations of 4 mm or less. The patients were managed with fortified tobramycin, fortified vancomycin, and moxifloxacin eye drops. No eyes required surgical intervention during treatment for the active infection, except for one eye with pre-existing no light perception that was enucleated because of chronic pain.

CONCLUSIONS

Moraxella keratitis is a less frequent form of bacterial keratitis that appears more prevalent in patients with previous ocular conditions. Early diagnosis of this infection and medical treatment with a conventional corneal ulcer regimen can result in good clinical outcomes without the need for a surgical intervention.

Unexpected and Sudden Death Due to Undiagnosed Moraxella catarrhalis Meningoencephalitis in a 40-day-old Infant: Case Report and Literature Review

Acute bacterial meningitis in infants and newborns represents a medical emergency and a significant cause of mortality and morbidity worldwide. Moraxella catarrhalis has been considered a microorganism with low pathogenic potential, and only in exceptional cases has it been found to cause meningitis in infants and immunocompetent people. We will now document an unusual case of an unexpected and sudden death of a 40-day-old infant due to acute meningitis from M. catarrhalis, apparently asymptomatic and subsequently diagnosed by an autopsy. According to our knowledge this is the first case of unexpected infant death due to undiagnosed M. catarrhalis meningitis.The suggested case, as well as for the rarity of such a fatal event, should be considered a caution to pediatrics and neonatologists for M. catarrhalis can cause paucisymptomatic meningoencephalitis in infants which can be potentially fatal.From a forensic point of view, an autopsy accompanied by a multidisciplinary assessment is always necessary in cases of unexpected infant deaths to identify the causes.

A Comparison between Two Pathophysiologically Different yet Microbiologically Similar Lung Diseases: Cystic Fibrosis and Chronic Obstructive Pulmonary Disease

Cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD) are chronic pulmonary diseases that affect ~70,000 and 251 million individuals worldwide, respectively. Although these two diseases have distinctly different pathophysiologies, both cause chronic respiratory insufficiency that erodes quality of life and causes significant morbidity and eventually death. In both CF and COPD, the respiratory microbiome plays a major contributing role in disease progression and morbidity. Pulmonary pathogens can differ dramatically during various stages of each disease and frequently cause acute worsening of lung function due to disease exacerbation. Despite some similarities, outcome and timing/type of exacerbation can also be quite different between CF and COPD. Given these clinical distinctions, both patients and physicians should be aware of emerging therapeutic options currently being offered or in development for the treatment of lung infections in individuals with CF and COPD. Although interventions are available that prolong life and mitigate morbidity, neither disorder is curable. Both acute and chronic pulmonary infections contribute to an inexorable downward course and may trigger exacerbations, culminating in loss of lung function or respiratory failure. Knowledge of the pulmonary pathogens causing these infections, their clinical presentation, consequences, and management are, therefore, critical. In this review, we compare and contrast CF and COPD, including underlying causes, general outcomes, features of the lung microbiome, and potential treatment strategies.

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

PURPOSE

The purpose of this study was to investigate the molecular mechanisms of fluoroquinolone resistance in Moraxella catarrhalis clinical strains isolated in Lublin, Poland.

MATERIALS AND METHODS

A 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.

RESULTS

It 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.

CONCLUSION

Our 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.

Novel broad-spectrum and long-acting parenteral cephalosporins having an acyl cyanamide moiety at the C-3 terminal: Synthesis and structure-activity relationships

A series of novel 7β-[2-(2-aminothiazole-4-yl)-2-(Z)-(alkoxyimino)acetamido]-cephalosporins having pyridinium-linked acyl cyanamide at the C-3 position were prepared and their antibacterial activities and pharmacokinetics profiles were evaluated. Most of the compounds exhibited potent antibacterial activities against penicillin-resistant Streptococcus pneumoniae (PRSP) and β-lactamase non-producing penicillin-resistant Haemophilus influenzae (BLNAR). Introduction of a propenyl group between the cephalospoin core and the side chains at the C-3 position improved the pharmacokinetics profile. Among these compounds, 7β-[2-(2-aminothiazole-4-yl)-2-(Z)- (alkoxyimino)acetamido]-3-(pyridin-1-ium-1-yl)prop-1-en-1-yl)cephalosporins (32j) showed well-balanced antibacterial activity against S. pneumoniae and H. influenzae which included resistant strains and also other Gram-positive or Gram-negative pathogens. Furthermore, 32j showed a long half-life comparable to that of Ceftriaxone in mice and monkeys.

Curative Effects of Suhuang Zhike Capsule on Postinfectious Cough: A Meta-Analysis of Randomized Trials

Objective. In this paper, we intended to systematically evaluate the efficacy of Suhuang Zhike Capsule (SZC) on postinfectious cough (PIC) in adults (age > 18). Methods. MEDLINE (PubMed), Chinese National Knowledge Infrastructure (CNKI), Cqvip Database (VIP), and Wanfang Database were researched for the randomized controlled trials (RCTs) of SZC for PIC. The search was limited to human studies, using the search keywords or free-text terms “cough,” “post-infectious cough,” “postinfectious cough,” “post-cold cough,” “postviral cough,” “postcold cough,” “Suhuang Zhike capsule,” “Chinese Medicine,” and “randomized clinical trials”. Two reviewers individually extracted data from the included RCTs and then the extracted data were analyzed using Review Manager 5.3 software. Results. Seven RCTs involving 573 patients entered the inclusion criteria. Findings suggested that, compared with western conventional medicine (WCM) and other Chinese medicine, SZC could effectively improve the efficacy rate (OR 2.68, 95%  CI, 1.48–4.84, P = 0.001; OR 4.86, 95%  CI, 1.50–15.73, P = 0.008, separately). Moreover, SZC could also improve the efficacy rate of Chinese medicine symptom (MD −0.74, 95%  CI, −1.46~−0.02, P = 0.04). However, in terms of cough relief time, more evidence is needed to prove that SZC have an earlier antitussive effect (MD −1.31, 95%  CI, −3.06~0.45, P = 0.14). Conclusion. The current evidence shows that SZC is effective in the treatment of PIC in adults and can significantly improve the effective rate of Chinese medicine symptoms.

Clinical characteristics of the patients with bacteremia due to Moraxella catarrhalis in children: a case-control study

BACKGROUND

Invasive diseases due to Moraxella catarrhalis are rare in children, even in immunocompromised hosts. Therefore, data regarding clinical characteristics and risk factors of such patients are limited. The aim of this study is to compare the clinical characteristics of patients with bacteremia due to Moraxella catarrhalis against those with bacteremia due to Streptococcus pneumoniae and Haemophilus influenzae.

METHODS

We performed a retrospective case-control study to compare patients younger than 18 years of age with positive blood cultures for the three pathogens between June 2008 and May 2014 at our institution. Data regarding patients' demographics and clinical course were collected from their medical records. Three group comparisons, with M. catarrhalis as reference, were made by the Fisher's exact test and Wilcoxon rank sum test for discrete and continuous variables, respectively.

RESULTS

There were eight cases of M. catarrhalis, 110 cases of S. pneumoniae (105 patients) and 22 cases of H. influenzae. The M. catarrhalis group consisted of six females (75 %) with a mean age of 16 months. The majority of patients (7/8, 88 %) had underlying diseases; however, only one was immunocompromised. Characteristically, six patients (75 %) had medical devices including trans-nasal devices (5/8, 63 %). Univariate analysis revealed that underlying conditions (P = 0.005), trans-nasal devices (P < 0.001), and lower body weight (P = 0.016) and low white blood cell count (P = 0.011) at the onset of illness were associated with the M. catarrhalis group compared to the S. pneumoniae group. Meanwhile, the higher rates of the patients with underlying conditions and trans-nasal devices were associated with the M. catarrhalis group compared to the H. influenzae group (P = 0.039, P < 0.001, respectively).

CONCLUSIONS

The presence of underlying conditions, particularly in those with trans-nasal devices, were characteristic features of patients with bacteremia due to M. catarrhalis.

Activity of Aristolochia bracteolata against Moraxella catarrhalis

A bioassay-guided fractionation of methanol extract of Aristolochia bracteolata whole plant was carried out in order to evaluate its antimicrobial activity and to identify the active compounds in this extract. Antibacterial and antifungal activities of methanol extract against gram-positive, gram-negative, and fungal strains were investigated by the agar disk diffusion method. Among the strains tested, Moraxella catarrhalis and sea urchin-derived Bacillus sp. showed the highest sensitivity towards the methanol extract and hence they are used as test organisms for the bioassay-guided fractionation. From this extract, aristolochic acid 1 (AA-1) has been isolated and has showed the greatest antibacterial activity against both standard strain and clinical isolates of Moraxella catarrhalis with equal minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 25 and 50 μg/mL. Modification of the AA-1 to AA-1 methyl ester completely abolished the antibacterial activity of the compound and the piperonylic acid moiety of AA-1 which suggested that the coexistence of phenanthrene ring and free carboxylic acid is essential for AA-1 antibacterial activity.

Moraxella Catarrhalis peritonitis

Background:

Peritonitis continues to be a major complication of peritonitis in peritoneal dialysis patients. Recent advances in connectology and better patient training have decreased the incidence of peritonitis in the last two decades. Peritonitis in PD patients is usually due to gram positive and less often due to gram negative organisms. Herein we report a case of peritonitis due to Moraxella Catarrhalis and review the literature on the diagnosis and treatment of this rare cause of peritonitis.

Case Report:

Our patient was a 56 year old man with end stage renal disease, on peritoneal dialysis, who was totally asymptomatic and on routine clinic visit was noted to have a high white blood cell count in his peritoneal fluid. Due to the nature of the organism, it took two weeks and two different microbiology laboratories to identify the organism and provide proper treatment.

Conclusions:

Peritonitis is the major cause of peritoneal dialysis failure and prompt recognition of the causative agent is of crucial importance to the proper and timely management of this complication.

bro {beta}-lactamase and antibiotic resistances in a global cross-sectional study of Moraxella catarrhalis from children and adults

OBJECTIVES

To compare and contrast the geographic and demographic distribution of bro beta-lactamase and antibiotic MIC(50/90) for 1440 global Moraxella catarrhalis isolates obtained from children and adults between 2001 and 2002.

METHODS

One thousand four hundred and forty M. catarrhalis isolates originating from seven world regions were investigated. The isolates were recovered from 411 children <5 years of age and 1029 adults >20 years of age. PCR-restriction fragment length polymorphism (RFLP) was performed to determine bro prevalence and to distinguish between bro types. MIC values of 12 different antibiotics were determined using the CLSI (formerly NCCLS) broth microdilution method.

RESULTS

Of the 1440 isolates, 1313 (91%) possessed the bro-1 gene and 64 (4%) possessed the bro-2 gene. Additionally, the prevalence of bro positivity between the child and adult age groups was significantly different (P < 0.0001), though bro-1 and bro-2 prevalences within age groups were not significantly different. Consistently higher beta-lactam MICs were observed for M. catarrhalis isolates originating in the Far East. Significant correlations in MICs were observed for several antibiotic combinations, including all five beta-lactams with each other, and among the two quinolones.

CONCLUSIONS

The worldwide prevalence of bro gene carriage in clinical isolates of M. catarrhalis is now approaching 95%, with children significantly more likely to harbour bro-positive isolates than adults. Further, statistically significant differences in the distribution of beta-lactam MICs were observed between different world regions, particularly with respect to the Far East.

Development of a disk diffusion method for testing Moraxella catarrhalis susceptibility using clinical and laboratory standards institute methods: a SENTRY antimicrobial surveillance program report

Currently, there is no Clinical and Laboratory Standards Institute (CLSI) disk diffusion method for testing Moraxella catarrhalis susceptibility. We examined 318 clinical strains of M. catarrhalis obtained as part of the SENTRY (Asia-Pacific) Antimicrobial Surveillance Program, plus two ATCC strains. MICs were determined by the CLSI standard broth microdilution method, and zone diameters were determined on Mueller-Hinton agar incubated in 5% CO(2). All strains were examined for the presence of BRO-1 and BRO-2 beta-lactamases by using molecular techniques. Tentative zone diameter interpretive criteria were successfully developed for 19 antimicrobial agents, including nine beta-lactams, using current MIC interpretive criteria where available or wild-type cutoff values where no prior criteria were available. The proposed interpretive criteria were highly accurate, with <or=0.7% very major (falsely susceptible) and <or=1.0% major (falsely resistant) errors, respectively.

Clinical and laboratory aspects of Moraxella catarrhalis bacteremia in children

Moraxella catarrhalis is an uncommon cause of bacteremia in children. We present 17 children with M. catarrhalis bacteremia. Most patients were <2 years old (76.4%), immunocompetent (82.3%), and had concomitant lower respiratory symptoms (76.5%). Moraxella catarrhalis bacteremia occurs in young immunocompetent children and is frequently associated with lower respiratory tract symptomatology.

[Antimicrobial susceptibility of 80 Moraxella catarrhalis strains isolated in the children's hospital of Tunis]

Eighty non-repetitive strains of Moraxella catarrhalis, isolated in Tunis Children's Hospital during five years from 1998 to 2002, were tested for their antimicrobial susceptibility, 95% of these strains were isolated from lung samples: 57.5% from trachea products, 35% from sputum and 2.5% from bronchial washings. The majority of strains (72%) were obtained from children under two years old. Antimicrobial susceptibility study showed that 95% of stains were beta-lactamase-producing, therefore they were penicillin G and amoxicillin resistant with high MICs. MIC(90) of penicillin G and amoxicillin of beta-lactamase-producing strains were respectively greater than 32 and 6 mg/l, these MIC decrease with addition of clavulanic acid. In fact, all strains studied were susceptible to the association amoxicillin-clavulanic acid as well as to cefotaxime. Concerning the other antimicrobial groups percentages of resistant strains found were as follows: erythromycin 3.75%, trimethoprim-sulfamethoxazol 12.5% and tetracycline 1.25%. Finally, all strains were susceptible to chloramphenicol, rifampicin and ciprofloxacin.

Pneumonia caused by Moraxella catarrhalis in haematopoietic stem cell transplant patients. Report of two cases and review of the literature

Moraxella catarrhalis is a gram negative diplococcus that causes a variety of upper and lower respiratory tract infections. Patients with malignant, hematological disorders treated with intensive cytotoxic chemotherapy, and recipients of various forms of haematopoietic stem cell transplant receiving immunosuppressive agents are at high risk of developing severe infections and septic complications. Early detection of the organism and prompt treatment with appropriate antibiotics provide both resolution of the infection and prevention of further consequences. Two patients with haematopoietic stem cell transplant who developed pneumonia caused by M. catarrhalis at King Faisal Specialist Hospital and Research Centre in Riyadh are reported and the literature is reviewed. To our knowledge, these are the first case reports of M. catarrhalis pneumonia in haematopoietic stem cell transplant patients.

Evaluation of susceptibility patterns and BRO beta-lactamase types among clinical isolates of Moraxella catarrhalis

The aims of this study were to detect BRO beta-lactamase types and to evaluate any correlation with the susceptibility patterns of 90 clinical isolates of Moraxella catarrhalis. The overall prevalences of the bro-1 and bro-2 genes were 78% and 12%, respectively. Penicillin G MICs for BRO-1+ isolates were significantly higher than those for BRO-2+ isolates. All the isolates were susceptible to amoxycillin-clavulanate, levofloxacin and cefixime. Resistance to clarithromycin, tetracycline and trimethoprim-sulphamethoxazole was 1.1%, 2.2% and 1.1%, respectively. One-step, length-based PCR was an efficient method to screen for BRO beta-lactamase genes.

Postinfectious cough: ACCP evidence-based clinical practice guidelines

BACKGROUND

Patients who complain of a persistent cough lasting >3 weeks after experiencing the acute symptoms of an upper respiratory tract infection may have a postinfectious cough. Such patients are considered to have a subacute cough because the condition lasts for no >8 weeks. The chest radiograph findings are normal, thus ruling out pneumonia, and the cough eventually resolves, usually on its own. The purpose of this review is to present the evidence for the diagnosis and treatment of postinfectious cough, including the most virulent form caused by Bordetella pertussis infection, and make recommendations that will be useful for clinical practice.

METHODS

Recommendations for this section of the guideline were obtained from data using a National Library of Medicine (PubMed) search dating back to 1950, which was performed in August 2004, of the literature published in the English language. The search was limited to human studies, using the search terms "cough," "postinfectious cough," "postviral cough," "Bordetella pertussis," "pertussis infection," and "whooping cough."

RESULTS

The pathogenesis of the postinfectious cough is not known, but it is thought to be due to the extensive inflammation and disruption of upper and/or lower airway epithelial integrity. When postinfectious cough emanates from the lower airway, this is often associated with the accumulation of an excessive amount of mucus hypersecretion and/or transient airway and cough receptor hyperresponsiveness; all may contribute to the subacute cough. In these patients, the optimal treatment is not known. Except for bacterial sinusitis or early on in a B pertussis infection, therapy with antibiotics has no role, as the cause is not bacterial infection. The use of inhaled ipratropium may be helpful. Other causes of postinfectious cough are persistent inflammation of the nose and paranasal sinuses, which leads to an upper airway cough syndrome (previously referred to as postnasal drip syndrome), and gastroesophageal reflux disease, which may be a complication of the vigorous coughing. One type of postinfectious cough that is particularly virulent is that caused by B pertussis infection. When the cough is accompanied by paroxysms of coughing, posttussive vomiting, and/or an inspiratory whooping sound, the diagnosis of a B pertussis infection should be made unless another diagnosis is proven. This infection is highly contagious but responds to antibiotic coverage with an oral macrolide when administered early in the course of the disease. A safe and effective vaccine to prevent B pertussis is now available for adults as well as children. It is recommended according to CDC guidelines.

CONCLUSIONS

In patients who have a cough lasting from 3 to 8 weeks with normal chest radiograph findings, consider the diagnosis of postinfectious cough. In most patients, a specific etiologic agent will not be identified, and empiric therapy may be helpful. A high degree of suspicion for cough due to B pertussis infection will lead to earlier diagnosis, patient isolation, and antibiotic treatment.

Antibiotic resistance patterns among respiratory pathogens at a German university children's hospital over a period of 10 years

Growing antimicrobial resistance among Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis is raising major concern worldwide. Strains of S. pneumoniae, H. influenzae and M. catarrhalis isolated from children with respiratory tract as well as invasive infection in a South-Western region of Germany between 1993 and 2002 were tested for susceptibility to common antibiotics including penicillins, cephalosporins and macrolides. A total of 2,362 S. pneumoniae, 2,501 H. influenzae, and 1,982 M. catarrhalis isolates were tested. Only two S. pneumoniae strains were found to be highly resistant to penicillin. The overall rate of intermediate resistance to penicillin was 3.5%. There was a significant increase in erythromycin resistance from 5% in 1993 to 12.2% in 2002 (P=0.001). No increase in ampicillin resistance was observed for H. influenzae over time. The rate of cefaclor resistance, however, increased from 4.5% to 11.8% (P<0.0001). Furthermore, a massive increase in erythromycin resistance from 26% to 40% was observed (P<0.0001). The vast majority of M. catarrhalis isolates were beta-lactamase positive, the minimal inhibitory concentration to ampicillin, however, exceeded only in 3% of all strains the cut-off of 1.5 mg/l. The erythromycin resistance rate of M. catarrhalis was 0.3%.

CONCLUSION

There is still a low rate of penicillin/ampicillin resistance in S. pneumoniae, and H. influenzae, but an alarming increase in resistance to erythromycin, and in H. influenzae a significant increase in cefaclor resistance was observed over the 10-year period in South-Western Germany.

Mode of action of the microbial metabolite GE23077, a novel potent and selective inhibitor of bacterial RNA polymerase

GE23077, a novel microbial metabolite recently isolated from Actinomadura sp. culture media, is a potent and selective inhibitor of bacterial RNA polymerase (RNAP). It inhibits Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) RNAPs with IC50 values (i.e. the concentration at which the enzyme activity is inhibited by 50%) in the 10(-8) m range, whereas it is not active on E. coli DNA polymerase or on eukaryotic (wheat germ) RNAP II (IC50 values > 10(-4) m in both cases). In spite of its potent activity on purified bacterial RNAPs, GE23077 shows a narrow spectrum of antimicrobial activity on Gram-positive and Gram-negative bacteria. To investigate the molecular basis of this behaviour, the effects of GE23077 on macromolecular biosynthesis were tested in E. coli cells permeabilized under different conditions. The addition of GE23077 to plasmolyzed cells resulted in an immediate and specific inhibition of intracellular RNA biosynthesis, in a dose-response manner, strongly suggesting that cell penetration is the main obstacle for effective antimicrobial activity of the antibiotic. Biochemical studies were also conducted with purified enzymes to obtain further insights into the mode of action of GE23077. Interestingly, the compound displays a behaviour similar to that of rifampicin, an antibiotic structurally unrelated to GE23077: both compounds act at the level of transcription initiation, but not on the sigma subunit and not on the formation of the promoter DNA-RNAP complex. Tests on different rifampicin-resistant E. coli RNAPs did not show any cross-resistance between the two compounds, indicating distinct binding sites on the target enzyme. In conclusion, GE23077 is an interesting new molecule for future mechanistic studies on bacterial RNAP and for its potential in anti-infective drug discovery.

Evaluation of restriction endonuclease analysis of BRO beta-lactamases in clinical and carrier isolates of Moraxella catarrhalis

A rapid increase in the prevalance of beta-lactamase producing M. catarrhalis isolates has highlighted its pathogenic potential. In this study, we aimed to detect the BRO beta-lactamases of our clinical (n = 32) and carrier (n =32) strains of Moraxella catarrhalis and compare the relationship of the enzyme type in assesment of MIC results of the antibiotics tested. BRO beta-lactamases were differentiated by restriction endonuclease analysis. Antibiotic susceptibility was performed by the agar dilution method recommended by NCCLS (M7A5). The clinical isolates produced 96.9%, whereas the carrier strains produced 90.6% beta-lactamase positivity by the restriction enzyme analysis. BRO-1 was isolated as 90.6% (n =29) while the BRO-2 and non-beta-lactamase producers (NBLP) were isolated as 6.3% (n =2) and 3.1% (n =1) respectively among clinical isolates. The rate of BRO-1 in the carrier strains was 75.0% (n =24), BRO-2 was 15.6% (n =5) and NBLP was 9.4%, (n =3). The beta-lactamase production with nitrocefin test was 96.9% (31/32) in clinical isolates and 90.6% (29/32) in carrier strains. M. catarrhalis needs a continous monitoring of antibiotic susceptibility; in this era restriction endonuclease analysis could be useful to screen BRO beta-lactamase genes.

Correlation between susceptibility and BRO type enzyme of Moraxella catarrhalis strains

Clinical isolates of Moraxella catarrhalis (76 isolates) were screened for beta-lactamase production and antibiotic susceptibility. beta-Lactamases (detected in 90.8% of isolates) were typed using isoelectric focusing to BRO-1 (87%) and BRO-2 (13%). Minor variations in electrofocusing patterns between the two types were seen. Isolates expressing BRO type enzymes showed solid resistance to penicillin, ampicillin and cephalothin, in particular BRO-1 producers. BRO-1 isolates were less susceptible to cephems and to beta-lactamase inhibitors than BRO-2 isolates. Isolates harbouring BRO-1 enzymes have more enzymatic activity than those expressed by BRO-2 isolates. Apart from resistance to tetracycline (14.5%), all isolates were consistently susceptible to erythromycin, chloramphenicol, ciprofloxacin and gentamicin. The conjugal transfer of BRO beta-lactamase gene(s) between M. catarrhalis isolates occurred with a frequency of 10(-5) to 10(-7)/donor cell. The data emphasize the importance of M. catarrhalis as an etiological agent spreading beta-lactamases that may inhibit some beta-lactams and lead to failure in treatment of mixed infections.

The Italian Epidemiological Survey 1997-1999. Antimicrobial susceptibility data of Haemophilus influenzae, Haemophilus parainfluenzae and Moraxella catarrhalis in Italy

The Italian Epidemiological Survey began a surveillance study with the aim of monitoring the antimicrobial resistance of respiratory pathogens. From 1997 to 1999, 2028 strains of Haemophilus influenzae and 523 strains of Haemophilus parainfluenzae were collected from 59 Clinical Microbiology Laboratories distributed throughout Italy. In 1998, the study was extended to include Moraxella catarrhalis and a total of 360 isolates were collected. There was a significant increase in the beta-lactamase production both for H. influenzae (from 5% in 1997 to 16% in 1999) and for H. parainfluenzae (from 5% in 1997 to 22% in 1999). Beta-lactamase production in M. catarrhalis was 84% in 1998 and 87% in 1999. Beta-lactamase production affected the susceptibility to unprotected penicillins (87% in H. influenzae, 85% in H. parainfluenzae and 34% in M. catarrhalis), and in part the susceptibility to cefaclor (about 98%). Amoxycillin/clavulanate, cefixime, ceftriaxone and ciprofloxacin were active against all strains of H. influenzae, H. parainfluenzae and M. catarrhalis.

Production of BRO beta-lactamases and resistance to complement in European Moraxella catarrhalis isolates

Of the 419 Moraxella catarrhalis isolates collected during the 1997-1999 European SENTRY surveillance study, 385 (92%) were beta-lactamase positive. Twenty-two (5.7%) produced BRO-2 beta-lactamase. Twenty-one new mutations were found in the putative promoter region of the bro genes. Nineteen percent of all isolates tested were complement sensitive. Resistance to beta-lactams is not linked to the phylogenetic lineages associated with susceptibility to complement.

Moraxella catarrhalis: from emerging to established pathogen

Moraxella catarrhalis (formerly known as Branhamella catarrhalis) has emerged as a significant bacterial pathogen of humans over the past two decades. During this period, microbiological and molecular diagnostic techniques have been developed and improved for M. catarrhalis, allowing the adequate determination and taxonomic positioning of this pathogen. Over the same period, studies have revealed its involvement in respiratory (e.g., sinusitis, otitis media, bronchitis, and pneumonia) and ocular infections in children and in laryngitis, bronchitis, and pneumonia in adults. The development of (molecular) epidemiological tools has enabled the national and international distribution of M. catarrhalis strains to be established, and has allowed the monitoring of nosocomial infections and the dynamics of carriage. Indeed, such monitoring has revealed an increasing number of B-lactamase-positive M. catarrhalis isolates (now well above 90%), underscoring the pathogenic potential of this organism. Although a number of putative M. catarrhalis virulence factors have been identified and described in detail, their relationship to actual bacterial adhesion, invasion, complement resistance, etc. (and ultimately their role in infection and immunity), has been established in a only few cases. In the past 10 years, various animal models for the study of M. catarrhalis pathogenicity have been described, although not all of these models are equally suitable for the study of human infection. Techniques involving the molecular manipulation of M. catarrhalis genes and antigens are also advancing our knowledge of the host response to and pathogenesis of this bacterial species in humans, as well as providing insights into possible vaccine candidates. This review aims to outline our current knowledge of M. catarrhalis, an organism that has evolved from an emerging to a well-established human pathogen.

Moraxella catarrhalis pneumonia during HIV disease

To assess the role of Moraxella catarrhalis complications in the setting of HIV disease, and to evaluate their occurrence and outcome according to several epidemiological, clinical, and laboratory parameters, the clinical records of 2123 consecutive HIV-infected patients hospitalized in a 9-year period were retrospectively reviewed, and 4 cases of community-acquired M. catarrhalis pneumonia were identified. Three adult patients had a diagnosis of AIDS and severe concurrent immunodeficiency (with a CD4+ lymphocyte count below 60 cells/microL), while the fourth case involved a child with vertical HIV disease. Leukopenia and neutropenia were never present, but no patient received a potent antiretroviral regimen at the time of disease onset. A concurrent respiratory infection by Streptococcus pneumoniae and Mycobacterium tuberculosis was recognized in 2 of 4 patients. Isolated M. catarrhalis strains were susceptible to all tested antimicrobial compounds (save ampicillin in 2 cases), and appropriate antimicrobial treatment led to clinical and microbiological cure in all described episodes. Only 8 cases of HIV-associated Moraxella spp. disease have been reported to date in seven different literature reports (6 cases of pneumonia, and 1 of septicemia). According to our experience, M. catarrhalis may be responsible for appreciable morbidity among patients with advanced HIV infection, especially when a low CD4+ cell count or coexisting respiratory disease are present. Clinicians and microbiologists who care for HIV-infected patients should carefully consider the potential pathogenic role of Moraxella spp. organisms.

Moraxella catarrhalis endocarditis: case report and review of the literature

A case of bacterial endocarditis caused by Moraxella catarrhalis in an apparently immunocompetent Greek male is presented, which was diagnosed after a 2-month history of low-grade fever of unknown origin. The agent seems to be a rare pathogen, but due to the high mortality rate, it should always be considered in the differential diagnosis of relevant cases. Beta-lactamase production by many strains complicates the choice of antibiotic.

Long-term trends in susceptibility of Moraxella catarrhalis: a population analysis

A retrospective, population analysis of antimicrobial susceptibility patterns was performed on Moraxella catarrhalis isolates recovered from a single medical centre to detect temporal trends and infer potential mechanisms of reduced susceptibility. The duration of this study, June 1984 to July 1994, encompassed the period during which the frequency of beta-lactamase production expanded from 30 to 96% in the population. MICs of penicillin G, cefamandole, ceftriaxone, amoxycillin/clavulanate, imipenem, clarithromycin, tetracycline, ciprofloxacin and trimethoprim/sulphamethoxazole for a representative sample of 375 isolates were determined. Analyses were conducted to test for variation in susceptibility among isolates, correlations of susceptibility levels among different antimicrobial agents, and temporal patterns in susceptibility. All antimicrobials except clarithromycin displayed significant differences among isolates within years, and mean MICs of all antimicrobial agents except tetracycline and clarithromycin varied significantly between years. Temporal trends to a reduction in susceptibility were detected to four of five beta-lactam antimicrobials (all except cefamandole). Significant correlations in MICs were uncovered among all pairs of four beta-lactam antimicrobials in both producers and non-producers of beta-lactamase. In contrast, cefamandole MICs were correlated only with ceftriaxone and penicillin, and these were limited to beta-lactam producing isolates; cefamandole and amoxycillin/clavulanate showed a correlation limited to non-producing isolates. For some antimicrobials, trends toward decreasing susceptibility may have been caused by an increased proportion of beta-lactamase producing isolates in the population, but the observation of significant decreases in susceptibility limited to beta-lactamase-producing isolates suggests that the underlying factors were different forms of beta-lactamase, beta-lactamase-dependent modifiers and/or additional factors.

Bordetella pertussis, Bordetella parapertussis, Mycoplasma pneumoniae, Chlamydia pneumoniae and persistent cough in children

Material collected during a prospective pertussis vaccine trial in 1992-95 was examined for Bordetella pertussis (culture and serology), Bordetella parapertussis (culture), Mycoplasma pneumoniae and Chlamydia pneumoniae (PCR). From 64% (99/155) of episodes with cough for less than 100 d, 115 aetiological agents were identified in one southern and one northern subset of DT-recipients. The most common single agent was B. pertussis, representing 56%(64/115), with a median cough period of 51 d, followed by M. pneumoniae 26%(30/115), 23 d, C. pneumoniae 17% (19/115), 26 d, and B. parapertussis 2% (2/115). For co-infections, the median duration of cough was about 60 d. Spasmodic cough for 21 d or more (clinical WHO criteria for pertussis) was present in 82% (41/50) of infections with B. pertussis as single agent, 38% (17/45) with B. parapertussis, 38% (5/13) with C. pneumoniae, 26% (5/19) with M. pneumoniae and 30%(17/56) in cases where no aetiology was found. In children with cough for more than 100 d (n = 78) using all vaccine arms, B. pertussis was responsible in 83% (65/78), in 21%(16/78) together with other agents. Acellular vaccines were more efficient against serious disease than whole cell vaccine. Antibiotic treatment was more common at the southern (34%) study site than at the northern one (12%). The findings indicate that diagnosis should rely on laboratory confirmation, both for rational treatment of an individual case and for monitoring outbreaks.