Molecular epidemiology of nontypeable Haemophilus influenzae causing community-acquired pneumonia in adults

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen which causes a variety of respiratory infections. The objectives of the study were to determine its antimicrobial susceptibility, to characterize the β-lactam resistance, and to establish a genetic characterization of NTHi isolates. Ninety-five NTHi isolates were analyzed by pulsed field gel electrophoresis (PFGE) and multi locus sequence typing (MLST). Antimicrobial susceptibility was determined by microdilution, and the ftsI gene (encoding penicillin-binding protein 3, PBP3) was PCR amplified and sequenced. Thirty (31.6%) isolates were non-susceptible to ampicillin (MIC ≥ 2 mg/L), with 10 of them producing β-lactamase type TEM-1 as a resistance mechanism. After ftsI sequencing, 39 (41.1%) isolates showed amino acid substitutions in PBP3, with Asn526 → Lys being the most common (69.2%). Eighty-four patients were successfully treated with amoxicillin/clavulanic acid, ceftriaxone and levofloxacin. Eight patients died due either to aspiration or complication of their comorbidities. In conclusion, NTHi causing CAP in adults shows high genetic diversity and is associated with a high rate of reduced susceptibility to ampicillin due to alterations in PBP3. The analysis of treatment and outcomes demonstrated that NTHi strains with mutations in the ftsI gene could be successfully treated with ceftriaxone or fluoroquinolones.

Molecular insights of co-trimoxazole resistance genes in Haemophilus influenzae isolated in Malaysia

In the last few decades, co-trimoxazole (SXT), an antibacterial combination of trimethoprim and sulfamethoxazole, has been used for treatment of upper respiratory tract infection due to Haemophilus influenzae. The usage of this antibiotic has become less important due to emergence of SXT-resistant strains worldwide. Most reports associate SXT resistance to the presence of variants of dihydrofolate reductase (DHFR) dfrA genes which are responsible for trimethoprim resistance; while the sulfamethoxazole (SMX) resistance are due to sulfonamide (SUL) genes sul1 and sul2 and/or mutation in the chromosomal (folP) gene encoding dihydropteroate synthetase (DHPS). This study aims to detect and analyse the genes that are involved in SXT resistance in H. influenzae strains that were isolated in Malaysia. Primers targeting for variants of dfrA, fol and sul genes were used to amplify the genes in nine SXT-resistant strains. The products of amplification were sequenced and multiple alignments of the assembled sequences of the local strains were compared to the sequences of other H. influenzae strains in the Genbank. Of the five variants of the dhfA genes, dfrA1 was detected in three out of the nine strains. In contrast to intermediate strains, at least one variant of folP genes was detected in the resistant strains. Multiple nucleotide alignment of this gene revealed that strain H152 was genetically different from the others due to a 15-bp nucleotide insert in folP gene. The sequence of the insert was similar to the insert in folP of H. influenzae strain A12, a strain isolated in United Kingdom. None of the strains had sul1 gene but sul2 gene was detected in four strains. Preliminary study on the limited number of samples shows that the TMP resistance was attributed to mainly to dfrA1 and the SMX was due to folP genes. Presence of sul2 in addition to folP in seven strains apparently had increased their level of resistance. A strain that lacked sul1 or sul2 gene, its resistance to sulfonamide was attributed to a 15-bp DNA insert in the folP gene.

Association of incidence of type 1 diabetes with mortality from infectious disease and with antibiotic susceptibility at a country level

To investigate the association between country incidence of type 1 diabetes and mortality from infectious disease and antibiotic susceptibility. An ecological study to explore the relationship at a country level of the reported incidence of type 1 diabetes (DiaMond) to infectious disease mortality (World Health Organisation) and to antibiotic susceptibility (Alexander Project). There were significant negative correlations between the incidence of type 1 diabetes and mortality for all infectious diseases studied. There were also significant positive correlations between the incidence of type 1 diabetes and antibiotic susceptibilities of Strep. pneumoniae, but not to those of Haem. influenzae. Since infectious disease mortality and antibiotic susceptibility are surrogate markers for bacterial exposure, our results provide support for a negative association between bacterial exposure in a community and its incidence of type 1 diabetes. The consistency of our results as well as the highly statistically significant results of most of the associations studied reinforces the validity of our findings.

Antimicrobial activity of the pleuromutilin antibiotic BC-3781 against bacterial pathogens isolated in the SENTRY antimicrobial surveillance program in 2010

BC-3781 is a novel semisynthetic pleuromutilin antibiotic inhibiting bacterial protein synthesis. BC-3781 has completed a phase 2 clinical trial in acute bacterial skin and skin structure infections (ABSSSI). Its antibacterial spectrum additionally covers the predominant pathogens causing community-acquired bacterial pneumonia (CABP). In this study, the antibacterial activity of BC-3781 was evaluated against a contemporary collection of 10,035 bacterial isolates predominately causing ABSSSI and CABP, among other infections, collected within the SENTRY Antimicrobial Surveillance Program worldwide in 2010. BC-3781 exhibited potent activity against organisms commonly isolated from ABSSSI such as Staphylococcus aureus (MIC50/90, 0.12/0.12 μg/ml; 99.8% inhibited at ≤0.5 μg/ml), beta-hemolytic streptococci (MIC50/90, 0.03/0.03 μg/ml; 99.3% inhibited at ≤0.5 μg/ml), and coagulase-negative staphylococci (CoNS; MIC50/90, 0.06/0.12 μg/ml; 97.8% inhibited at ≤1 μg/ml). BC-3781 displayed similar MIC distributions among methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) S. aureus strains. BC-3781 was also active against Enterococcus faecium, with 76.3% of vancomycin-susceptible and 97.0% of vancomycin-resistant isolates being inhibited at BC-3781 concentrations of ≤1 μg/ml. Beta-hemolytic and viridans group streptococci were highly susceptible to BC-3781, with 99.3% and 96.7% of isolates inhibited at ≤0.5 μg/ml, respectively. Further, activity of BC-3781 against Streptococcus pneumoniae (MIC50/90, 0.12/0.25 μg/ml), Haemophilus influenzae (MIC50/90, 1/2 μg/ml), and Moraxella catarrhalis (MIC50/90, 0.12/0.25 μg/ml) was not negatively influenced by β-lactamase production or resistance to other antimicrobial classes tested. In all, BC-3781 displayed a very potent antibacterial profile including the most prevalent bacterial pathogens causing ABSSSI and CABP, thus warranting further clinical development of this antibiotic in these and possibly other indications.

Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis

Background

Indigenous children in Australia and Alaska have very high rates of chronic suppurative lung disease (CSLD)/bronchiectasis. Antibiotics, including frequent or long-term azithromycin in Australia and short-term beta-lactam therapy in both countries, are often prescribed to treat these patients. In the Bronchiectasis Observational Study we examined over several years the nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in these two PCV7-vaccinated populations.

Methods

Indigenous children aged 0.5–8.9 years with CSLD/bronchiectasis from remote Australia (n = 79) and Alaska (n = 41) were enrolled in a prospective cohort study during 2004–8. At scheduled study visits until 2010 antibiotic use in the preceding 2-weeks was recorded and nasopharyngeal swabs collected for culture and antimicrobial susceptibility testing. Analysis of respiratory bacterial carriage and antibiotic resistance was by baseline and final swabs, and total swabs by year.

Results

Streptococcus pneumoniae carriage changed little over time. In contrast, carriage of Haemophilus influenzae declined and Staphylococcus aureus increased (from 0% in 2005–6 to 23% in 2010 in Alaskan children); these changes were associated with increasing age. Moraxella catarrhalis carriage declined significantly in Australian, but not Alaskan, children (from 64% in 2004–6 to 11% in 2010). While beta-lactam antibiotic use was similar in the two cohorts, Australian children received more azithromycin. Macrolide resistance was significantly higher in Australian compared to Alaskan children, while H. influenzae beta-lactam resistance was higher in Alaskan children. Azithromycin use coincided significantly with reduced carriage of S. pneumoniae, H. influenzae and M. catarrhalis, but increased carriage of S. aureus and macrolide-resistant strains of S. pneumoniae and S. aureus (proportion of carriers and all swabs), in a ‘cumulative dose-response’ relationship.

Conclusions

Over time, similar (possibly age-related) changes in nasopharyngeal bacterial carriage were observed in Australian and Alaskan children with CSLD/bronchiectasis. However, there were also significant frequency-dependent differences in carriage and antibiotic resistance that coincided with azithromycin use.

Antimicrobial resistance among respiratory Haemophilus influenzae isolates from pulmonology services over a six-year period

BACKGROUND

Respiratory tract infections (RTI) are frequently caused by Haemophilus influenzae. Widespread antibacterial resistance among respiratory microorganisms complicates empirical RTI treatment. Therefore, national data on antibiotic resistance for H. influenzae are important for guiding optimal antibiotic choice.

METHODS

The antibiotic susceptibility of H. influenzae strains isolated from respiratory specimens of patients admitted to the pulmonology services between 2005 and 2010 was assessed. Isolates were collected annually from 13 hospitals in the Netherlands as part of the national intramural antimicrobial resistance surveillance performed by the Dutch Working Group on Antibiotic Policy (SWAB). Breakpoints for resistance were in accordance with the criteria of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Trend analysis was performed using logistic regression analysis.

RESULTS

In total, 1606 H. influenzae strains were analyzed. The prevalence of antibiotic resistance to amoxicillin, co-amoxiclav, doxycycline, co-trimoxazole, and clarithromycin was stable over the 6-y period, and there was a trend towards a decrease in the prevalence of beta-lactamase-producing isolates. Regarding prevalences, no significant trends were observed.

CONCLUSIONS

Our study showed no significant changes in antibiotic resistance for H. influenzae isolated at different hospitals in the Netherlands over a 6-y period. Regular surveillance remains important in controlling the prevalence of resistance, since actual resistance data should be taken into account when the choice of an empiric antibiotic is made.

Evaluation of Antimicrobial Treatments in Children with Acute Otitis Media in Spain: A Pharmacokinetic-Pharmacodynamic (PK/PD) Approach

Pharmacokinetic/pharmacodynamic (PK/PD) principles are priceless tools for evaluating the effectiveness of different antimicrobial treatments for different infections. However, very few studies deal with pediatric dosages and take into account the unbound drug serum levels. Our study is focused on the most frequent antibiotic dosing schedules used in Spain for the treatment of acute otitis media (AOM) in children, where high rates of penicillin and macrolide resistance exist among pneumococcal isolates. Pharmacokinetic parameters of antibiotics in children where obtained from the literature. The minimum inhibitory concentrations (MIC90) of antibiotics for pediatric strains of Streptococcus pneumoniae and Haemophilus influenzae were obtained from the SAUCE 2 project. Only ceftriaxone (50 mg/kg single intramuscular dose) and high doses of co-amoxiclav (27-33 mg/kg q8h) provided adequate efficacy indexes (tss(%)>MIC) for both S. pneumoniae and H. influenzae in AOM in children. These results are consistent with MEF (medium ear fluid) levels obtained from the literature. Our results confirm the utility of serum unbound levels to predict efficacy of antibiotics in children with AOM.

In VitroStudies on the Impact of Human Serum on the Antibacterial Effect of Faropenem

The interaction between faropenem and serum in determining antibacterial effect was studied using three target pathogens and two different in vitro methodologies. Strains of Staphylococcus aureus, Streptococcus pneumoniae, capsulate and non capsulate Haemophilus influenzae, all faropenem MIC 0.12 mg/L, were tested in a range of pharmacologically realistic faropenem concentrations with various proportions of serum up to 75%. Using simulated serum bactericidal titres the presence of human serum reduced the activity of faropenem against S. pneumoniae as did heat-treated serum for non-capsulate H. influenzae. Serum on its own was bactericidal against H. influenzae probably due to the presence of complement. The antibacterial effects of combinations of faropenem and serum was assessed in time-kill curves by calculation of the area-under-the bacterial-kill-curve (AUBKC). This was then related to faropenem concentration and the proportion of serum using three-dimensional plots. Serum on its own was mildly inhibitory of the growth of S. aureus, supported improved growth of S. pneumoniae at some proportions and was rapidly bactericidal to H. influenzae, especially the non-capsulate strains. Faropenem had a marked antibacterial effect against all three species in the range 0-2.5 mg/L. Increasing the faropenem concentration from 2.5-10 mg/L produced little or no additional effect. The combination of serum and faropenem had little impact on the antibacterial effect against S. pneumoniae and S. aureus but free drug concentrations were likely to be greater than the MIC in all the combinations used. Against capsulate H. influenzae the effect of serum and faropenem was broadly equivalent while against non-capsulate strains the activity of serum was so great it is difficult to assess the impact of faropenem alone. The interaction between serum and antibiotic in determining antibacterial effect is complex and critically dependent on the proportions of serum and drug concentrations chosen. Three-dimensional plots offer a tool to visualise these complex relationships which may be species specific.

Nationwide survey of the development of drug resistance in the pediatric field in 2007 and 2010: drug sensitivity of Haemophilus influenzae in Japan (second report)

The Drug-Resistant Pathogen Surveillance Group in Pediatric Infectious Disease conducted national surveillance for Haemophilus influenzae in 2007 (phase 3) and 2010 (phase 4), following the previous surveillance conducted from 2000 to 2001 (phase 1) and in 2004 (phase 2). We examined the antimicrobial susceptibility for H. influenzae derived from clinical specimens of pediatric patients collected nationwide from 27 institutions during phases 3 (386 strains) and 4 (484 strains). The frequency of β-lactamase-nonproducing ampicillin (ABPC)-resistant (BLNAR) strains, which rapidly increased from 11.4 % in phase 1 to 43.4 % in phase 2, has gradually decreased from 38.3 % in phase 3 to 37.8 % in phase 4. In contrast, On the other hand, the frequency of β-lactamase-producing strains, which continuously decreased from 8.3 % in phase 1 to 4.4 % in phase 3, has increased to 8.7 % in phase 4. Prevalence of β-lactamase-producing clavulanic acid/amoxicillin-resistant (BLPACR) strains, especially, has increased from 1.6 % in phase 3 to 4.8 % in phase 4. The oral antimicrobial agents with the lowest MIC90 were levofloxacin in both phases, and tosufloxacin in phase 4 (≤0.063 μg/ml), whereas for intravenous use the corresponding agent was tazobactam/piperacillin in both phases (0.125 μg/ml). There was no increase in the MIC90 of most β-lactams between phase 3 and phase 4. In relationship to sex, age, presence of siblings, attendance at a daycare center, siblings' attendance at a daycare center, and prior administration of antimicrobial agents within 1 month, the frequency of β-lactamase-nonproducing ABPC-intermediately resistant (BLNAI) strains + BLNAR strains was high (P = 0.005) in cases with prior administration of antimicrobial agents in phase 3.

Human neutrophil elastase degrades SPLUNC1 and impairs airway epithelial defense against bacteria

Background

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a significant cause of mortality of COPD patients, and pose a huge burden on healthcare. One of the major causes of AECOPD is airway bacterial (e.g. nontypeable Haemophilus influenzae [NTHi]) infection. However, the mechanisms underlying bacterial infections during AECOPD remain poorly understood. As neutrophilic inflammation including increased release of human neutrophil elastase (HNE) is a salient feature of AECOPD, we hypothesized that HNE impairs airway epithelial defense against NTHi by degrading airway epithelial host defense proteins such as short palate, lung, and nasal epithelium clone 1 (SPLUNC1).

Methodology/Main Results

Recombinant human SPLUNC1 protein was incubated with HNE to confirm SPLUNC1 degradation by HNE. To determine if HNE-mediated impairment of host defense against NTHi was SPLUNC1-dependent, SPLUNC1 protein was added to HNE-treated primary normal human airway epithelial cells. The in vivo function of SPLUNC1 in NTHi defense was investigated by infecting SPLUNC1 knockout and wild-type mice intranasally with NTHi. We found that: (1) HNE directly increased NTHi load in human airway epithelial cells; (2) HNE degraded human SPLUNC1 protein; (3) Recombinant SPLUNC1 protein reduced NTHi levels in HNE-treated human airway epithelial cells; (4) NTHi levels in lungs of SPLUNC1 knockout mice were increased compared to wild-type mice; and (5) SPLUNC1 was reduced in lungs of COPD patients.

Conclusions

Our findings suggest that SPLUNC1 degradation by neutrophil elastase may increase airway susceptibility to bacterial infections. SPLUNC1 therapy likely attenuates bacterial infections during AECOPD.

Antimicrobial activity of ceftaroline and comparator agents tested against bacterial isolates causing skin and soft tissue infections and community-acquired respiratory tract infections isolated from the Asia-Pacific region and South Africa (2010)

Ceftaroline, the active metabolite of the prodrug ceftaroline fosamil, is a cephalosporin with in vitro bactericidal activity against resistant Gram-positive organisms including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant strains of Streptococcus pneumoniae, and common Gram-negative organisms, including wild-type Enterobacteriaceae. We evaluated the in vitro activity of ceftaroline and selected comparator agents against bacterial isolates collected from patients with skin and soft tissue infections (SSTI) and community-acquired respiratory tract infections (CARTI) in the Asia-Pacific region and South Africa. A total of 2351 isolates, 1100 from SSTI and 1251 from CARTI, were collected from 25 medical centers distributed across 8 countries as part of the 2010 AWARE ceftaroline surveillance program and tested for susceptibility by reference broth microdilution methods. Ceftaroline was very active against S. aureus (MIC50/90, 0.25/1 μg/mL; 93.4% susceptible), including MRSA (MIC50/90, 1/2 μg/mL; 80.6% susceptible). Against β-hemolytic streptococci, ceftaroline demonstrated greater activity (MIC90, 0.015 μg/mL) than penicillin (MIC90, 0.06 μg/mL). Ceftaroline was also highly active against viridans group streptococci (MIC90, 0.12 μg/mL). Similarly to ceftriaxone, ceftaroline activity against Escherichia coli (MIC50/90, >32/>32 μg/mL) and Klebsiella spp. (MIC50/90, 0.12/>32 μg/mL) was compromised by the high prevalence of isolates with an ESBL phenotype in the region, particularly in China. Ceftaroline was the most potent β-lactam tested against S. pneumoniae (MIC50/90 of 0.015/0.25 μg/mL; 99.8% susceptible by Clinical and Laboratory Standards Institute [CLSI] criteria), and it was also highly potent against Haemophilus influenzae (MIC50/90, ≤ 0.008/0.03 μg/mL; 100% susceptible by CLSI criteria). Ceftaroline was also active against H. parainfluenzae (MIC50/90, ≤ 0.008/0.015 μg/mL) and Moraxella catarrhalis (MIC50/90, 0.06/0.12 μg/mL). In summary, ceftaroline showed potent in vitro activity against a large collection of bacterial isolates (2351) associated with SSTI and CARTI from the Asia-Pacific region and South Africa.

Haemophilus influenzae as an airborne contamination in child day care centers

BACKGROUND

The aim of this study was to assess the exposure of children to airborne Haemophilus influenzae in day care centers.

METHODS

Air samples were taken using an Andersen impactor in 32 rooms designed for children stay. The concentrations of airborne bacteria were calculated as colony forming units (CFU) (growing on trypticase soy agar) per cubic meter of air (CFU/m(3)). The compositions of bioaerosol were determined on blood trypticase soy agar and Haemophilus selective agar. Isolated strains were identified using API NH strips and apiweb software. The antibiotic resistance of H influenzae strains was determined by the disk diffusion method.

RESULTS

Compared with the proposed criteria for microbiologic quality of indoor air, the rooms were characterized by the very high bacterial contamination of the air. The prevailing component of bacterial aerosol was gram-positive cocci. Airborne H influenzae strains were found in 25% of the investigated rooms and were mostly classified as biotype II (33%).

CONCLUSION

It may be accepted that the exposure to airborne H influenzae is typical of child day care centers in contrast to indoor environments with older population. Child day care center contribute to the expansion of H influenzae in human population via air. Generally, airborne H influenzae isolates from the investigated child day care centers were susceptible to older antibiotics such as ampicillin and amoxicillin-clavulanic acid.

[Antimicrobial susceptibility of community-acquired respiratory tract pathogens isolated from patients in primary hospitals in Shanghai from 2007 to 2010]

OBJECTIVE

To investigate the etiology of community-acquired respiratory tract infections (CARTI) and the antimicrobial resistance of the major pathogens in primary hospitals in Shanghai.

METHODS

Patients with CARTI were prospectively recruited from 30 primary hospitals from December 2007 to July 2010. Those who had used antimicrobials within previous 2 weeks were excluded from the study. The clinical information such as temperature, white blood cell (WBC) count and percentage of neutrophils was recorded, and throat swab or deep cough sputum was collected to isolate pathogens. The specimens were collected and couriered to the Zhongshan Hospital microbiology laboratory within 2 h for bacterial culture. The minimal inhibition concentrations (MIC) of penicillin G, amoxicillin, cephradine, cephalexin, cefadroxil, sulfamethoxazole/trimethoprim and azithromycin were determined using the agar dilution test.

RESULTS

Totally 806 qualified cases were enrolled in this study. Fever (T ≥ 38 °C) was present in 51.7% (n = 417) , and increased WBC count (>10×10(9)/L) was noted in 68.5% (n = 552 cases) of the patients. For bacterial culture, 184 strains were isolated from throat swabs of 688 patients with upper respiratory infection; the most frequently isolated bacteria were Haemophilus influenzae (44, 23.9%), Staphylococcus aureus (44, 23.9%) and Group G streptococcus (43, 23.0%). Thirty-three strains were isolated from 118 patients with lower respiratory infections, with Haemophilus influenza (21, 63.6%), Group G streptococcus (6,18.2%) and Streptococcus pneumoniae (3,9.1%) as the leading pathogens. All strains of Haemophilus influenzae were susceptible to azithromycin. The susceptibility rate of Streptococcus pneumoniae to penicillin was as high as 94.7%, while that to azithromycin was significantly decreased (21.1%). The MIC90 values of cephalexin, cefadroxil and ceftazidime for β-hemolytic streptococcus spp were ≤ 2 mg/L.

CONCLUSIONS

Upper respiratory infections were responsible for most cases of CARTI. The commonly used antimicrobials in primary hospitals kept a high susceptibility to the frequent pathogens for CARTI. However, Streptococcus pneumoniae showed a decreased susceptibility to macrolides, which should be used carefully as a single agent when treating CARTI.

Comparison study of single and concurrent administrations of carbapenem, new quinolone, and macrolide against in vitro nontypeable Haemophilus influenzae mature biofilms

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen and a common cause of otitis media in children, chronic bronchitis, and pneumonia in patients with chronic obstructive pulmonary disease. Many studies have reported that NTHi is capable of producing biofilms, which may be one of the important factors involved in chronic diseases and accelerating antimicrobial resistance. Unfortunately, there is still no consensus about the elimination of biofilms. In this study, concurrent administrations of levofloxacin (LVFX)-imipenem (IPM) and clarithromycin (CAM)-IPM, as well as the single administration of IPM, LVFX, and CAM, were performed to treat the mature biofilms produced by NTHi, respectively. Biofilm inhibition was quantified using microtiter biofilm assay (MBA), and relative biomass was calculated as the ratio compared to that of untreated control biofilms. The relative biomasses of biofilms treated with IPM, LVFX-IPM, and CAM-IPM against a β-lactamase-negative ampicillin-resistant strain was 1.10, 0.08, and 0.13 at 1× minimum inhibitory concentration (MIC), 0.90, 0.05, and 0.07 at 10× MIC, and 0.80, 0.06, and 0.07 at 100× MIC, respectively. Biofilms were also visually observed by scanning electron microscopy, and a focused ion-beam system showed that high concentrations of combined administration strongly inhibited the biofilms, which was consistent with the results of MBA. Our data demonstrated the antibiofilm effect of concurrent administration against mature NTHi biofilms, which indicated a rationale for the potential use of concurrent administrations in diseases involving chronic NTHi biofilms.

[Microbial structure of acute bacterial conjunctivitis]

Microbiological investigation of 124 patients with acute conjunctivitis which were treated in one of Tbilisi policlinics in 2010-12 years, was performed; microbial structure containing 124 microbial strains of different species was detected. Namely, following species of microorganisms were isolated: S. aureus - 35 strains (28,2%), Str. pneumoniae - 10 strains (8,1%), S. epidermidis - 6 strains (4,8%), Ps. aeruginosa - 24 strains (19,4%), Moraxella catarrhalis - 21 strains (16,9%), Haemophilus influenzae biogroup aegipticus - 17 strains (13,7%), and Klebsiella pneumoniae - 11 strains (8,9%). Identification of microorganisms was performed using classic methods of microbiological explorations and test systems API (bio Meriux). Study of sensitivity/resistance to antibiotics (ciprofloxacin, levofloxacin, tobramicin, norfoloxacin, moxifloxacin) containing in eye drops, was performed by diffusion in agar. High level of resistance to this antibiotic was found. As a result it is recommended to perform microbiological investigation in each case of acute conjunctivitis, to receive rational treatment.

Effect of low-intensity focused ultrasound on the middle ear in a mouse model of acute otitis media

We hypothesized that low-intensity focused ultrasound (LIFU) increases vessel permeability and antibacterial drug activity in the mouse middle ear. We determined appropriate settings by applying LIFU to mouse ears with the external auditory canal filled with normal saline and performed histologic and immunohistologic examination. Acute otitis media was induced in mice with nontypable Haemophilus influenzae, and they were given ampicillin (50, 10, or 2 mg/kg) intraperitoneally once daily for 3 days with or without LIFU (1.0 W/cm(2), 20% duty cycle, 30 s). In the LIFU(+) groups receiving the 2- and 10-mg/kg doses, viable bacteria counts, number of inflammatory cells and IL-1β and TNF-α levels in middle ear effusion were significantly lower than in the LIFU(-) groups on the same doses. Severity of AOM also tended to be reduced more in the LIFU(+) groups than in the LIFU(-) groups. LIFU application with antibiotics may be effective for middle ear infection.

Genetic diversity of the ftsI gene in β-lactamase-nonproducing ampicillin-resistant and β-lactamase-producing amoxicillin-/clavulanic acid-resistant nasopharyngeal Haemophilus influenzae strains isolated from children in South Korea

Haemophilus influenzae frequently colonizes the nasopharynx of children and adults, which can lead to a variety of infections. We investigated H. influenzae carriage in the nasopharynx of 360 children, in terms of (1) the prevalence of strains with decreased susceptibility, and (2) the presence of amino acid substitutions in PBP3. One hundred twenty-three strains were isolated (34.2%, 123/360), 122 of which were classified as nontypable H. influenzae (NTHi). Of these, β-lactamase-nonproducing ampicillin-susceptible strains accounted for 26.2%, β-lactamase-producing-ampicillin-resistant strains for 9.0%, β-lactamase-nonproducing ampicillin-resistant (BLNAR) strains for 40.2%, and β-lactamase-producing amoxicillin-/clavulanic acid-resistant (BLPACR) for 24.6%, respectively. Pulsed field gel electrophoresis (PFGE) patterns were so diverse that they were clustered into 41 groups. The amino acid substitutions in the transpeptidase domain (292 amino acids) of ftsI in BLNAR isolates showed that group IIb accounted for 30.6%, IIc for 8.2%, IId for 16.3%, III for 32.7%, and the others for 12.2%. Moreover, groups IIb (56.7%; 17/30) and III (23.3%; 7/30) were prevalent among BLPACR strains. They were subclassified into more diverse sequence subtypes by analysis of the entire PBP3 (610 amino acids). Groups IIb, IIc, IId, and III exhibited 13, four, six, and four sequence subtypes, respectively. Such a genetic diversity is likely indicative of significant potential for decreased antimicrobial susceptibility in nasopharyngeal-colonizing NTHi strains.

[In vitro activity of doripenem against strains from pediatric diseases and strains causing purulent meningitis]

This study evaluated the in vitro activity of doripenem (DRPM) against 200 Streptococcus pneumoniae and 197 Haemophilus influenzae from children and adults in 2007, 50 H. influenzae type b in 2006, 20 Listeria monocytogenes in 1990-2005, 23 Neisseria meningitidis in 2007-2009 and 83 Bordetella pertussis in 1989-2003. All strains were isolated from Japanese clinical facilities. We also investigated in vitro activity of other carbapenems (meropenem, imipenem, panipenem, biapenem), cephems (ceftriaxone, cefotaxime), ampicillin and clarithromycin. The all MICs were determined by a broth micro dilution method or an agar dilution method according to CLSI. The MIC90(s) of DRPM against S. pneumoniae and H. influenzae from children were 0.25 microg/mL, 1 microg/mL, respectively, which were similar to strains from adults. These results suggested that antibacterial activity of DRPM is not variable by patient's age. DRPM also showed excellent activities against H. influenzae type b, L. monocytogenes and N. meningitidis, which cause purulent meningitis, and B. pertussis causing whooping cough more than the other carbapenems. DRPM showed superior activities against serious strains of pediatric infection diseases.

[Morphological changes in penicillin-resistant Streptococcus pneumoniae and beta-lactamase-nonproducing, ampicillin-resistant Haemophilus influenzae after exposure to oral antibacterial agents]

Morphological changes in penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase-nonproducing, ampicillin-resistant Haemophilus influenzae (BLNAR) after exposure to oral antibacterial agents could be observed over time under a phase-contrast microscope. Morphological changes in BLNAR were also observed using a scanning electron microscope. The organisms used in this study were ME19F strain identified as genotypic(g) gPRSP (serotype: 19F) and JPH002 strain identified as gBLNAR (serotype: b). The antibacterial agents used were amoxicillin (AMPC), cefditoren (CDTR), tebipenem (TBPM), and tosufloxacin (TFLX). The concentration of each antibacterial agent to which the bacteria were exposed was set at the blood level one hour after Cmax when administered to children at the usual dose. Bacteriolysis of gPRSP cells started after exposure of only 20minutes to TBPM, and 90% of the cells were lysed within 2 hours. A high bactericidal action of TBPM on gPRSP was supported by these findings. When gBLNAR was exposed to AMPC and TBPM, lysis from spheroplasts and cells with vacuoles were sometimes observed. In contrast, after gBLNAR was exposed to CDTR, lysis occurred after marked filamentation in the cells, but after exposure to TFLX, cells deduced to be killed after mild filamentation without lysis. Time-dependent morphological changes that reflect the differences in bactericidal activity and PBP affinity among beta-lactams provide beneficial information to select antibacterial agents.

[Antibacterial susceptibility surveillance of Haemophilus influenzae isolated from pediatric patients in Gifu and Aichi prefectures (2009-2010)]

We investigated the susceptibility to antibacterial agents of 197 strains of Haemophilus influenzae isolated from pediatric patients at medical facilities in Gifu and Aichi prefectures between 2009 and 2010. Those strains were also examined for the mutations of ftsI coding for penicillin-binding protein 3, presence of bla TEM-1, serotype and beta-lactamase producing ability. Among the 197 strains, the most prevalent serotype was non-typeable (89.8%), followed by serotype b (8.1%), e (1.5%) and f (0.5%). Based on the susceptibility among the 197 strains to antibacterial agents, beta-lactamase nonproducing ampicillin-susceptible H. influenzae (BLNAS) accounted for 27.4%, beta-lactamase nonproducing ampicillin-resistant H. influenzae (BLNAR) for 62.4%, beta-lactamase producing ampicillin-resistant H. influenzae (BLPAR) for 6.1% and beta-lactamase producing amoxicillin/ clavulanic acid-resistant H. influenzae (BLPACR) for 4.1%. According to PCR-based genotyping, the strains were classified into 6 categories: gBLNAS, gLow-BLNAR, gBLNAR, gBLPAR, gBLPACR-I and gBLPACR-II. The incidences of each resistant class were 17.3% for gBLNAS, 6.6% for gLow-BLNAR, 66.0% for gBLNAR, 5.6% for gBLPAR and 4.6% for gBLPACR-II. The combined incidence of gLow-BLNAR and gBLNAR was 72.6%, which was higher than that of BLNAR (62.4%). The MIC90s of antibacterial agents against the 197 strains were as follows; 0.0156 microg/mL for tosufloxacin and garenoxacin, 0.0313 microg/mL for levofloxacin and pazufloxacin, 0.0625 microg/mL for norfloxacin, 0.25 microg/mL for tazobactam/piperacillin (TAZ/PIPC) and ceftriaxone, 0.5 microg/mL for TAZ/PIPC (1:8) and cefditoren, 1 microg/mL for piperacillin, cefteram, cefotaxime, meropenem, tebipenem and minocycline, 2 microg/mL for doripenem, 4 microg/mL for cefcapene, imipenem and azithromycin, 8 microg/mL for sulbactam/ampicillin, clavulanic acid/amoxicillin (1:2, CVA/AMPC) and cefdinir, 16 microg/mL for CVA/AMPC (1:14), flomoxef and clarithromycin, 32 microg/mL for ampicillin. Although there was no rapid increase in the antibacterial resistance, the prevalence of BLNAR was still over 50%. In order to ensure the appropriate chemotherapy, it is important to continue the surveillance of susceptibility among H. influenzae.

Disk diffusion and MIC quality control ranges for BC-3205 and BC-3781, two novel pleuromutilin antibiotics

MIC and disk diffusion quality control (QC) ranges were established for two new pleuromutilin antimicrobials (BC-3205 and BC-3781) in an eight-laboratory study performed according to Clinical and Laboratory Standards Institute M23-A3 guidelines. Staphylococcus aureus ATCC 29213 and 25923, Streptococcus pneumoniae ATCC 49619, and Haemophilus influenzae ATCC 4927 strains were evaluated. The proposed QC ranges would aid clinical laboratories in testing these compounds following their development for treatment of respiratory and cutaneous infections.

AWARE Ceftaroline Surveillance Program (2008-2010): trends in resistance patterns among Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in the United States

Ceftaroline fosamil, the prodrug form of the active metabolite ceftaroline, is a new broad-spectrum parenteral cephalosporin with antibacterial activity against the prevalent respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Bacterial resistance surveillance (5330 isolates) was conducted in the United States between 2008 and 2010 to assess the in vitro activity of ceftaroline and comparator antibacterial agents against invasive respiratory isolates of S. pneumoniae (3329 isolates), H. influenzae (1545 isolates), and M. catarrhalis (456 isolates). All organisms were cultured from patient infections in 71 US hospital laboratories and were submitted to a central reference monitor for broth microdilution testing by Clinical and Laboratory Standards Institute reference methods. Against S. pneumoniae, ceftaroline inhibited 98.7% of strains at the susceptible breakpoint of ≤ 0.25 µg/mL (50% minimum inhibitory concentration [MIC(50)], 0.01 µg/mL; 90% MIC [MIC(90)], 0.12 µg/mL) and was 16-fold more active than ceftriaxone (MIC(90), 2 µg/mL). Among 70 ceftriaxone-resistant pneumococcal isolates, all were inhibited by ≤ 0.5 µg/mL of ceftaroline. Haemophilus influenzae (MIC(50), ≤ 0.008 µg/mL; MIC(90), 0.015 µg/mL) and M. catarrhalis (MIC(50), 0.06 µg/mL; MIC(90), 0.12 µg/mL) were very susceptible to ceftaroline regardless of β-lactamase production. Whereas the high-level of activity of ceftaroline was maintained against S. pneumoniae and H. influenzae from 2008 through 2010, increased rates of nonsusceptibility were observed for amoxicillin/clavulanate, erythromycin, and levofloxacin among S. pneumoniae and for trimethoprim/sulfamethoxazole and azithromycin among H. influenzae. In summary, ceftaroline resistance surveillance (Assessing Worldwide Antimicrobial Resistance Evaluation [AWARE] Program) in the United States (2008-2010) documented in vitro sustained potency and spectrum against Gram-positive and Gram-negative pathogens known to cause community-acquired bacterial pneumonia.

Antibiotic susceptibility profile of Haemophilus influenzae and transfer of co-trimoxazole resistance determinants

Prior to the implementation of Haemophilus influenzae type b vaccination worldwide, H. influenzae has been one of the main causative agents of community acquired pneumonia and meningitis in children. Due to the lack of information on the characteristics of the H. influenzae isolates that have previously been collected in Malaysia, the H. influenzae were assessed of their microbial susceptibility to commonly used antibiotics. Emphasis was made on strains that were resistance to co-trimoxazole (SXT) and their mode of transfer of the antibiotic resistance determinants were examined. A collection of 34 H. influenzae isolates was serotyped and antimicrobial susceptibility tests were performed to 11 antibiotics. To the isolates that were found to be resistant to co-trimoxazole, minimum inhibition concentration (MIC) to SXT was performed using Etest while agar dilution method was used to measure the individual MICs of trimethoprim (TMP) and sulfamethoxazole (SUL). These isolates were also examined for presence of plasmid by PCR and isolation method. Conjugal transfers of SXT-resistant genes to SXT-susceptible hosts were performed to determine their rate of transfer. Result showed that 20.6% of the total number of isolates was serotype B while the remaining was non-typeable. Antimicrobial susceptibility profile of all the isolates revealed that 58.8% was resistant to at least one antibiotic. Majority of these isolates were equally resistant to ampicillin and tetracycline (29.4% each), followed by resistance to SXT (26.5%). From nine isolates that were found to be SXT-resistant, five contained plasmid/s. Conjugal transfer experiment showed that these five isolates with plasmid transferred SXT-resistance determinants at a higher frequency than those without. From these observations, it is postulated that plasmid is not involved in the transfer of SXT-resistance genes but presence of plasmid facilitates their transfer. The information obtained from this study provides some basic knowledge on the antimicrobial susceptibility pattern of the H. influenzae isolates and their mode of transfer of SXT-resistance genes.

Summary of ceftaroline activity against pathogens in the United States, 2010: report from the Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) surveillance program

The Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) surveillance program is a sentinel resistance monitoring system designed to track the activity of ceftaroline and comparator agents. In the United States, a total of 8,434 isolates were collected during the 2010 surveillance program from 65 medical centers distributed across the nine census regions (5 to 10 medical centers per region). All organisms were isolated from documented infections, including 3,055 (36.2%) bloodstream infections, 2,282 (27.1%) respiratory tract infections, 1,965 (23.3%) acute bacterial skin and skin structure infections, 665 (7.9%) urinary tract infections, and 467 (5.5%) miscellaneous other infection sites. Ceftaroline was the most potent β-lactam agent tested against staphylococci. The MIC(90) values were 1 μg/ml for methicillin-resistant Staphylococcus aureus (MRSA; 98.4% susceptible) and 0.5 μg/ml for methicillin-resistant coagulase-negative staphylococci (CoNS). Ceftaroline was 16- to 32-fold more potent than ceftriaxone against methicillin-susceptible staphylococcal strains. All staphylococcus isolates (S. aureus and CoNS) were inhibited at ceftaroline MIC values of ≤ 2 μg/ml. Ceftaroline also displayed potent activity against streptococci (MIC(90), 0.015 μg/ml for beta-hemolytic streptococci; MIC(90), 0.25 μg/ml for penicillin-resistant Streptococcus pneumoniae). Potent activity was also shown against Gram-negative pathogens (Haemophilus influenzae, Haemophilus parainfluenzae, and Moraxella catarrhalis). Furthermore, wild-type strains of Enterobacteriaceae (non-extended-spectrum β-lactamase [ESBL]-producing strains and non-AmpC-hyperproducing strains) were often susceptible to ceftaroline. Continued monitoring through surveillance networks will allow for the assessment of the evolution of resistance as this new cephalosporin is used more broadly to provide clinicians with up-to-date information to assist in antibiotic stewardship and therapeutic decision making.

Isolation, structure elucidation, and antibacterial activity of methiosetin, a tetramic acid from a tropical sooty mold (Capnodium sp.)

Drug-resistant bacteria continue to make many existing antibiotic classes ineffective. In order to avoid a future epidemic from drug-resistant bacterial infections, new antibiotics with new modes of action are needed. In an antibiotic screening program for new drug leads with new modes of action using antisense Staphylococcus aureus Fitness Test screening, we discovered a new tetramic acid, methiosetin, from a tropical sooty mold, Capnodium sp. The fungus also produced epicorazine A, a known antibiotic. The structure and relative configuration of methiosetin was elucidated by 2D NMR and ESIMS techniques. Methiosetin and epicorazine A showed weak to modest antibacterial activity against S. aureus and Haemophilus influenzae. The isolation, structure elucidation, and antibacterial activity of both compounds are described.