Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States over a 10-year period: Alexander Project

Molecular epidemiology of Streptococcus pneumoniae isolates causing invasive and noninvasive infection in Ethiopia

Streptococcus pneumoniae, a medically important opportunistic bacterial pathogen of the upper respiratory tract, is a major public health concern, causing a wide range of pneumococcal illnesses, both invasive and noninvasive. It is associated with significant global morbidity and mortality, including pneumonia, meningitis, sepsis, and acute otitis media. The major purpose of this study was to determine the molecular epidemiology of Streptococcus pneumoniae strains that cause invasive and noninvasive infections in Ethiopia. A prospective study was undertaken in two regional hospitals between January 2018 and December 2019. Whole-genome sequencing was used to analyze all isolates. Serotypes and multilocus sequence types (MLST) were derived from genomic data. The E-test was used for antimicrobial susceptibility testing. Patient samples obtained 54 Streptococcus pneumoniae isolates, 33 from invasive and 21 from noninvasive specimens. Our findings identified 32 serotypes expressed by 25 Global Pneumococcal Sequence Clusters (GPSCs) and 42 sequence types (STs), including 21 new STs. The most common sequence types among the invasive isolates were ST3500, ST5368, ST11162, ST15425, ST15555, ST15559, and ST15561 (2/33, 6% each). These sequence types were linked to serotypes 8, 7 C, 15B/C, 16 F, 10 A, 15B, and 6 A, respectively. Among the noninvasive isolates, only ST15432, associated with serotype 23 A, had numerous isolates (4/21, 19%). Serotype 14 was revealed as the most resistant strain to penicillin G, whereas isolates from serotypes 3, 8, 7 C, and 10 A were resistant to erythromycin. Notably, all serotype 6 A isolates were resistant to both erythromycin and penicillin G. Our findings revealed an abnormally significant number of novel STs, as well as extremely diversified serotypes and sequence types, implying that Ethiopia may serve as a breeding ground for novel STs. Recombination can produce novel STs that cause capsular switching. This has the potential to influence how immunization campaigns affect the burden of invasive pneumococcal illness. The findings highlight the importance of continuous genetic surveillance of the pneumococcal population as a vital step toward enhancing future vaccine design.

Pneumococcal Immunization Strategies for High-Risk Pediatric Populations Worldwide: One Size Does Not Fit All

Despite the significant reduction in pneumococcal disease due to pneumococcal vaccines, protection of vulnerable high-risk individuals, especially pediatric populations, remains a great challenge. In an effort to maximize the protection of high-risk children against pneumococcal disease, a combined schedule that includes both conjugate and polysaccharide vaccines is recommended by several countries in the developed world. On the other hand, middle- and low-income countries do not have in place established policies for pneumococcal immunization of children at risk. Pneumococcal conjugate vaccines, despite their benefits, have several limitations, mainly associated with serotype replacement and the wide range of serotype coverage worldwide. In addition, PPV23-impaired immunogenicity and the hyporesponsiveness effect among populations at risk have been well-documented. Therefore, the added value of continuing to include PPV23 in vaccination schedules for high-risk individuals in the years to come remains to be determined by monitoring whether the replacing/remaining serotypes causing IPD are covered by PPV23 to determine whether its benefits outweigh its limitations. In this review, we aim to describe serotype distribution and vaccine efficacy data on pneumococcal disease in the pre- and post-PCV implementation era among high-risk children in both developed and developing countries, assessing the optimization of current recommendations for their vaccination against pneumococcal disease.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Manganese complex [Mn(CO)3(tpa-κ3N)]Br increases antibiotic sensitivity in multidrug resistant Streptococcus pneumoniae

OBJECTIVES

The emergence of multidrug-resistance (MDR) in Streptococcus pneumoniae clones and non-vaccine serotypes necessitate the development of novel treatment strategies. This work aimed to determine the efficacy of the Mn complex [Mn(CO)³(tpa-κ³N)]Br against clinically important MDR strains of S. pneumoniae.

METHODS

Twenty MDR clinicalS. pneumoniae strains were included in this study. Minimum inhibitory concentrations (MICs) of [Mn(CO)₃(tpa-κ³N)]Br were determined via broth microdilution alone and in combination with other antimicrobial agents using checkerboard assays and/or disc diffusion tests. In vitro efficacy was assessed by time-kill assays while in vivo efficacy was tested using the insect model Galleria mellonella.

RESULTS

[Mn(CO)₃(tpa-κ³N)]Br showed moderate in vitro efficacy against S. pneumoniae coupled with bactericidal activity. Checkerboard and disc diffusion assays showed synergy between [Mn(CO)₃(tpa-κ³N)]Br and tetracycline, and the combination of both agents caused rapid kill-kinetics and reduced the MIC below the susceptibility breakpoint of 1 mg/L even for tetracycline-resistant strains of S. pneumoniae. Similar results were observed for the erythromycin- and the co-trimoxazole-Mn complex combination. In the G. mellonella infection model, mortality and morbidity rates at 96 h were significantly lower in larvae treated with [Mn(CO)₃(tpa-κ³N)]Br than phosphate buffered saline, while treatment with the tetracycline-Mn complex combination was superior to monotherapy, resulting in significantly lower mortality and morbidity rates (p < 0.049).

CONCLUSIONS

We show that [Mn(CO)₃(tpa-κ³N)]Br has in vitro and in vivo antibacterial activity against clinically relevant strains of S. pneumoniae and has the potential to be used in combination with currently available antibiotics to increase their effectiveness against MDR S. pneumoniae.

Novel Protein-Based Pneumococcal Vaccines: Assessing the Use of Distinct Protein Fragments Instead of Full-Length Proteins as Vaccine Antigens

Non-serotype-specific protein-based pneumococcal vaccines have received extensive research focus due to the limitations of polysaccharide-based vaccines. Pneumococcal proteins (PnPs), universally expressed among serotypes, may induce broader immune responses, stimulating humoral and cellular immunity, while being easier to manufacture and less expensive. Such an approach has raised issues mainly associated with sequence/level of expression variability, chemical instability, as well as possible undesirable reactogenicity and autoimmune properties. A step forward employs the identification of highly-conserved antigenic regions within PnPs with the potential to retain the benefits of protein antigens. Besides, their low-cost and stable construction facilitates the combination of several antigenic regions or peptides that may impair different stages of pneumococcal disease offering even wider serotype coverage and more efficient protection. This review discusses the up-to-date progress on PnPs that are currently under clinical evaluation and the challenges for their licensure. Focus is given on the progress on the identification of antigenic regions/peptides within PnPs and their evaluation as vaccine candidates, accessing their potential to overcome the issues associated with full-length protein antigens. Particular mention is given of the use of newer delivery system technologies including conjugation to Toll-like receptors (TLRs) and reformulation into nanoparticles to enhance the poor immunogenicity of such antigens.

Prevalence and antibiotic resistance pattern of bacteria isolated from urinary tract infections in Northern Iran

Background:

This study aimed to investigate the bacteria associated with urinary tract infection (UTI) and antibiotic susceptibility pattern of the isolates during 2013–2015 in Northern Iran.

Materials and Methods:

Overall 3798 patients with clinical symptoms of UTI were subjected as samples, and they were cultured and pure isolated bacteria were identified using biochemical tests and subjected to antibiogram assessment using disc diffusion method.

Results:

Totally, 568 (14.96%) from 3798 patients had positive UTI. Four hundred and ninety-seven (87.5%) from 568 isolated bacteria were resistant to at least one antibiotic. Escherichia coli, Staphylococcus spp., and Pseudomonas spp. were the most prevalent bacteria. Isolated bacteria indicated the highest antibiotic resistance to methicillin (76.06%) and ampicillin (89.29%) and also revealed the most sensitivity to imipenem (99.1%) and amikacin (91.57%). Statistical analysis of the resistance pattern trend during 3 years indicated the insignificant increase (P > 0.05) in antibiotic resistance of the isolates.

Conclusion:

The results of this study revealed a great concern for emerging UTI-related multidrug-resistant strains of bacteria causing UTI in Iran.

Professional practice evaluation of emergency department prescriptions for community-acquired infections in Lebanon

BACKGROUND

Selecting the appropriate antibiotic regimen is extremely important in improving patient outcomes, minimizing antimicrobial resistance, and reducing costs. This study was conducted to evaluate current prescribing practices for empiric antibiotics at the time of admission to the emergency department (ED) and to assess their appropriateness in Lebanon.

METHODS

A retrospective observational study was conducted at three different Lebanese hospitals between June and December 2016. Adult patients who received antibiotics in the ED during the study period were included. The assessment of antibiotic therapy based on adherence to international guidelines, including the choice of antibiotic, dosing, or both, was considered for analysis.

RESULTS

A total of 258 patients who had a single diagnosis of an infectious disease were included. Adherence to international guidelines was noted in only 32.6% of cases; the frequency was highest for skin and soft tissue infections (50.0%), followed by urinary tract infections (40%). Among the different antibiotic classes, the highest percentage of drug incompatibility was for β-lactam prescriptions (70.8%). The percentage of incompatibility with guidelines for administered regimens on the basis of drug selection, dosing, or both was 53.4%, 10.3%, and 36.2%, respectively.

CONCLUSIONS

Inappropriate antibiotic use in the ED is prevalent, and physician adherence to international guidelines for empiric antibiotic prescriptions in the ED remains low. This emphasizes the importance of monitoring the use of antibiotics in the ED, as there is growing concern for antibiotic resistance and healthcare safety.

Bacterial RadA is a DnaB-type helicase interacting with RecA to promote bidirectional D-loop extension

Homologous recombination (HR) is a central process of genome biology driven by a conserved recombinase, which catalyses the pairing of single-stranded DNA (ssDNA) with double-stranded DNA to generate a D-loop intermediate. Bacterial RadA is a conserved HR effector acting with RecA recombinase to promote ssDNA integration. The mechanism of this RadA-mediated assistance to RecA is unknown. Here, we report functional and structural analyses of RadA from the human pathogen Streptococcus pneumoniae. RadA is found to facilitate RecA-driven ssDNA recombination over long genomic distances during natural transformation. RadA is revealed as a hexameric DnaB-type helicase, which interacts with RecA to promote orientated unwinding of branched DNA molecules mimicking D-loop boundaries. These findings support a model of DNA branch migration in HR, relying on RecA-mediated loading of RadA hexamers on each strand of the recipient dsDNA in the D-loop, from which they migrate divergently to facilitate incorporation of invading ssDNA.

Bacterial homologous recombination involves the actions of RadA and RecA to promote single-stranded DNA integration. Here the authors report the structure of RadA from Streptococcus pneumoniae and demonstrate that it acts as a hexameric DnaB-type helicase.

What is the clinical relevance of drug-resistant pneumococcus?

PURPOSE OF REVIEW

Pneumococcal infections are a major cause of morbidity and mortality worldwide. In recent years, Streptococcus pneumoniae has shown increasing resistance to a several antibiotics, becoming a worldwide problem. The impact of antibiotic resistance of S. pneumoniae on clinical outcomes is still controversial. The principal reason for this controversy is the existence of several factors related to the patients and to the pathogen that may influence how antibiotic resistance patterns affect clinical outcomes. The aim of this review is to discuss current knowledge of the epidemiological data on antibiotic resistance; we also discuss mechanisms and risk factors for antibiotic resistance.

RECENT FINDINGS

The phenomenon of serotype replacement after the introduction of conjugate pneumococcal vaccinations and the escalation of antibiotic resistance worldwide remains an important issue in terms of their impact on clinical outcomes in pneumococcal disease. Antimicrobial resistance of pneumococcus leads to changes in the clinical presentation of pneumococcal disease, making it more difficult to diagnose and to treat. Consumption of antibiotics in the community is directly proportional to antimicrobial resistance. Carriage of S. pneumoniae and infection with antibiotic-resistant pneumococcus is associated with prior antibiotic therapy, extremes of age, presence of comorbidities (i.e. COPD), attendance at child day care centers, crowded conditions, intra-familial transmission, and nursing home residence.

SUMMARY

Antibiotic-resistant S. pneumoniae is a worldwide problem. The implementation of several strategies including vaccine campaigns, prudent use of current antibiotics, and programs for the surveillance of pneumococcal infections, could limit the increasing resistance of this pathogen to antimicrobials.

Fluoroquinolone resistance of Streptococcus pneumoniae isolates causing invasive disease: special focus on zabofloxacin

The present study examined the in vitro activity of various antibiotics including zabofloxacin, against isolates responsible for invasive pneumococcal diseases. Between 1997 and 2008, a total of 208 isolates were collected from sterile fluids, including blood (n=196, 94.2%), pleural fluid (n=5, 2.4%), cerebrospinal fluid (n=5, 2.4%), and ascites (n=2, 1.0%). Zabofloxacin showed the lowest MIC50 (0.015μg/mL) and MIC90 (0.025μg/mL) values of all the tested antibiotics. Rates of isolates resistant to penicillin (MIC ≥8μg/mL), ceftriaxone (MIC ≥4μg/mL) and levofloxacin (MIC ≥8μg/mL) were 3.4%, 0.4% and 2.0%, respectively. Four isolates (2.0%) were resistant to levofloxacin, and zabofloxacin showed low MICs (range, 0.025-0.125μg/mL). Zabofloxacin shows potent in vitro activity against S. pneumoniae isolates that caused invasive disease, even strains that are resistant to levofloxacin.

Extensively drug-resistant Streptococcus pneumoniae, South Korea, 2011-2012

To better understand extensively drug resistant Streptococcus pneumoniae, we assessed clinical and microbiological characteristics of 5 extensively drug-resistant pneumococcal isolates. We concluded that long-term care facility residents who had undergone tracheostomy might be reservoirs of these pneumococci; 13- and 23-valent pneumococcal vaccines should be considered for high-risk persons; and antimicrobial drugs should be used judiciously.

Antibiotics use patterns for surgical prophylaxis site infection in different surgical wards of a teaching hospital in ahvaz, iran

BACKGROUND

Despite the effectiveness of prophylactic antimicrobials to prevent surgical site infection the use of antibiotic prophylaxis is often inappropriate.

OBJECTIVES

The current study aimed to determine the pattern of prophylactic antibiotic use in a teaching hospital affiliated to Jundishapur University of Medical Sciences, Ahvaz, Iran.

PATIENTS AND METHODS

The current descriptive study included 8586 patients who received prophylactic antibiotics before surgery from April 2011 to March 2012, in Razi Hospital affiliated to Jundishapur University of Medical Sciences. Indications for antibiotic use, proper or inappropriate antibiotics, an antibiotic or combination of antibiotics, dosage and length of treatment for each patient based on the infectious disease textbook (Mandel's Principle and practice of infectious diseases) definitions were administrated.

RESULTS

Of the total 8586 patients who took antibiotics for preventive purposes, 4815 (56%) required antimicrobial prophylaxis, and 3771 (44%) patients did not. Of the 4815 patients who received prophylaxis, 86.9% received it appropriately, 13.1% received it inappropriately; 8.2% received inappropriate dosage, and 9.5% received antibiotic longer than 24 hours.

CONCLUSIONS

The current study revealed that 44% of those who received prophylaxis did not need it. In the patients who received antibiotics, the most common mistakes were antibiotic selection followed by prolonged prophylaxis (> 24 hours) and excess dose.

New paradigms in the pathogenesis of otitis media in children

Acute otitis media (AOM) is a multifactorial disease with a significant socioeconomic impact. The pathogenesis of AOM is attributed to a variety of well-established internal and extrinsic factors. Recent evidence strongly points to bacterial biofilm formation as an important contributor to this disease entity. The nasopharynx is a likely reservoir for infection with subsequent seeding of pathogens to the middle ear via planktonic shedding. Various modalities have been used to directly detect biofilm formation in the middle ear mucosa of children with AOM. Further insights into this disease may lead to new strategies for prevention and treatment.

Systemic antibiotic use among children and adolescents in Germany: a population-based study

The aim of the study was to comprehensively describe antibiotic use among children and young adolescents in Germany. Outpatient prescriptions of systemic antibiotics to children (<15 years) were analysed using data from four German statutory health insurances for the years 2004 to 2006. Annual prevalence of antibiotic prescriptions was determined using the average number of insured children during the respective year as reference population. Annual antibiotic prescription rates were calculated per 1,000 person years. Both figures were stratified by age (0-4, 5-9 and 10-14 years) and sex. Frequent indications for prescribing were analysed. Annual prevalence of antibiotic prescriptions rose from 35.68 % [95 % confidence intervals (CI), 35.62-35.75] in 2004 to 37.79 % [95 % CI, 37.72-37.86] in 2006. Prescription rates slightly increased by 6.01 % from 668.54 [95 % CI, 667.34-669.72] antibiotic prescriptions per 1,000 person years in 2004 to 708.71 [95 % CI, 707.47-709.95] in 2006. In 2006, prescriptions of broad-spectrum penicillins (25.09 %), second-generation cephalosporins (18.11 %) and narrow-spectrum penicillins (16.45 %) were most frequent. The most common indication for antibiotic prescribing was tonsillitis followed by bronchitis, otitis media, acute upper respiratory infections and scarlet fever.

CONCLUSION

In contrast to other northern European countries, paediatric prescription rates are high in Germany. This and the frequent prescribing of broad spectrum agents for the treatment of mostly viral self-limiting conditions indicate limited adherence to evidence-based practice guidelines in antibiotic prescribing in the German outpatient setting.

Functionally cloned pdrM from Streptococcus pneumoniae encodes a Na(+) coupled multidrug efflux pump

Multidrug efflux pumps play an important role as a self-defense system in bacteria. Bacterial multidrug efflux pumps are classified into five families based on structure and coupling energy: resistance−nodulation−cell division (RND), small multidrug resistance (SMR), major facilitator (MF), ATP binding cassette (ABC), and multidrug and toxic compounds extrusion (MATE). We cloned a gene encoding a MATE-type multidrug efflux pump from Streptococcus pneumoniae R6, and designated it pdrM. PdrM showed sequence similarity with NorM from Vibrio parahaemolyticus, YdhE from Escherichia coli, and other bacterial MATE-type multidrug efflux pumps. Heterologous expression of PdrM let to elevated resistance to several antibacterial agents, norfloxacin, acriflavine, and 4′,6-diamidino-2-phenylindole (DAPI) in E. coli KAM32 cells. PdrM effluxes acriflavine and DAPI in a Na⁺- or Li⁺-dependent manner. Moreover, Na⁺ efflux via PdrM was observed when acriflavine was added to Na⁺-loaded cells expressing pdrM. Therefore, we conclude that PdrM is a Na⁺/drug antiporter in S. pneumoniae. In addition to pdrM, we found another two genes, spr1756 and spr1877,that met the criteria of MATE-type by searching the S. pneumoniae genome database. However, cloned spr1756 and spr1877 did not elevate the MIC of any of the investigated drugs. mRNA expression of spr1756, spr1877, and pdrM was detected in S. pneumoniae R6 under laboratory growth conditions. Therefore, spr1756 and spr1877 are supposed to play physiological roles in this growth condition, but they may be unrelated to drug resistance.

Risk factors for multidrug-resistant invasive pneumococcal disease in South Africa, a setting with high HIV prevalence, in the prevaccine era from 2003 to 2008

The emergence of multidrug-resistant (MDR) Streptococcus pneumoniae complicates disease management. We aimed to determine risk factors associated with MDR invasive pneumococcal disease (IPD) in South Africa and evaluate the potential for vaccination to reduce disease burden. IPD data collected by laboratory-based surveillance from 2003 through 2008 were analyzed. Multidrug resistance was defined as nonsusceptibility to any three or more different antibiotic classes. Risk factors for multidrug resistance were evaluated using multivariable logistic regression. Of 20,100 cases of IPD identified, 3,708 (18%) had MDR isolates, with the proportion increasing from 16% (461/2,891) to 20% (648/3,326) (P < 0.001) over the study period. Serotypes included in the 13-valent pneumococcal conjugate vaccine (PCV13) accounted for 94% of MDR strains. Significant risk factors for MDR IPD included PCV13 (1,486/6,407; odds ratio [OR] of 6.3; 95% confidence interval [CI] of 5.0 to 7.9) and pediatric (3,382/9,980; OR of 12.8; 95% CI of 10.6 to 15.4) serotypes, age of <5 (802/3,110; OR of 2.0; 95% CI of 1.8 to 2.3) or ≥65 (39/239; OR of 1.5; 95% CI of 1.0 to 2.2) years versus age of 15 to 64 years, HIV infection (975/4,636; OR of 1.5; 95% CI of 1.2 to 1.8), previous antibiotic use (242/803; OR of 1.7; 95% CI of 1.4 to 2.1), previous hospital admissions (579/2,450; OR of 1.2; 95% CI of 1.03 to 1.4), urban location (883/4,375; OR of 2.0; 95% CI of 1.1 to 3.5), and tuberculosis treatment (246/1,021; OR of 1.2; 95% CI of 1.03 to 1.5). MDR IPD prevalence increased over the study period. The effect of many of the MDR risk factors could be reduced by more judicious use of antibiotics. Because PCV13 serotypes account for most MDR infections, pneumococcal vaccination may reduce the prevalence of multidrug resistance.

Outcome measurement of extensive implementation of antimicrobial stewardship in patients receiving intravenous antibiotics in a Japanese university hospital

BACKGROUND

Antimicrobial stewardship has not always prevailed in a wide variety of medical institutions in Japan.

METHODS

The infection control team was involved in the review of individual use of antibiotics in all inpatients (6348 and 6507 patients/year during the first and second annual interventions, respectively) receiving intravenous antibiotics, according to the published guidelines, consultation with physicians before prescription of antimicrobial agents and organisation of education programme on infection control for all medical staff. The outcomes of extensive implementation of antimicrobial stewardship were evaluated from the standpoint of antimicrobial use density, treatment duration, duration of hospital stay, occurrence of antimicrobial-resistant bacteria and medical expenses.

RESULTS

Prolonged use of antibiotics over 2 weeks was significantly reduced after active implementation of antimicrobial stewardship (2.9% vs. 5.2%, p < 0.001). Significant reduction in the antimicrobial consumption was observed in the second-generation cephalosporins (p = 0.03), carbapenems (p = 0.003), aminoglycosides (p < 0.001), leading to a reduction in the cost of antibiotics by 11.7%. The appearance of methicillin-resistant Staphylococcus aureus and the proportion of Serratia marcescens to Gram-negative bacteria decreased significantly from 47.6% to 39.5% (p = 0.026) and from 3.7% to 2.0% (p = 0.026), respectively. Moreover, the mean hospital stay was shortened by 2.9 days after active implementation of antimicrobial stewardship.

CONCLUSION

Extensive implementation of antimicrobial stewardship led to a decrease in the inappropriate use of antibiotics, saving in medical expenses, reduction in the development of antimicrobial resistance and shortening of hospital stay.

Nasopharyngeal Carriage, Antibiotic Resistance and Serotype Distribution of Streptococcus Pneumoniae among Healthy Adolescents in Zahedan

BACKGROUND

Colonization of nasopharynx by Streptococcus pneumoniae can lead to pneumococcal diseases. This study was performed to determine the carriage rate of nasopharyngeal S. pneumoniae in adolescents, antibiotic susceptibility and serotype prevalence in Zahedan, Iran.

METHODS

Nasopharyngeal specimens from 865 adolescents (age range: 10-19 years old) attending eight schools in Zahedan, Iran, were collected and assessed by standard procedures to recover S. pneumoniae. The serotyping was carried out by latex agglutination test and the minimum inhibitory concentrations (MIC) of penicillin as well as other commonly used antibiotics were determined by a broth dilution method.

RESULTS

Pneumococci were recovered from 15.7% (136/865, 95% confidence interval (CI) 12.3-18.9) of total samples which 119 isolates were typable with the available antisera. 1, 19A, 15C, 9V, 11A and 19F were found as the most frequent serotypes. Ninety three pneumococcal isolates were sensitive to penicillin. The MIC values of antibiotics tested were (μg/ml): penicillin 0.01-4, cefotaxime 0.01-4, ceftriaxone 0.02-128, chloramphenicol 0.08-32, ciprofloxacin 0.06-16, erythromycin 0.01-128, tetracycline 0.08-128 and vancomycin 0.02-1.

CONCLUSION

A clear diversity was seen in the serotype distribution of the S. pneumoniae isolates and most of the antibiotic resistant strains belonged to few serotypes. Healthy adolescents in Zahedan, Iran commonly show pneumococcal carriage and antibiotic resistance.

Antibiotic resistance in sputum isolates of Streptococcus pneumoniae in chronic obstructive pulmonary disease is related to antibiotic exposure

Streptococcus pneumoniae (S. pneumoniae) is recovered from sputum of patients with chronic obstructive pulmonary disease (COPD) during stable disease and exacerbations. In patients with community acquired pneumonia, antibiotic exposure in the prior 3-6 months is associated with recovery of antibiotic resistant isolates of S. pneumoniae. Whether the same relationship is seen in COPD is not known. From April 1994 to June 2004, 127 adults with COPD were enrolled in a prospective longitudinal study. Sputum isolates of S. pneumoniae were characterized with susceptibility testing and pulsed-field gel electrophoresis (PFGE). The relationship between antibiotic use in the previous 3 and 6 months with either new acquisition of a resistant pneumococcal isolate or development of resistance (4-fold increase in MIC) in a pre-existing colonizing pneumococcal strain was determined. A total of 194 pneumococcal isolates were recovered from 38 patients. Among 71 newly acquired and 4 resistance-emergent strains analyzed further, rates of resistance to penicillin (MIC ≥2), erythromycin (MIC ≥1), tetracycline (MIC ≥8) and trimethoprim/sulfamethoxazole (MIC ≥4) were 8%, 24%, 17% and 16% respectively. Flouroquinolone resistance was not seen. Among strains isolated from patients exposed to a macrolide within 6 months, 53.6% displayed erythromycin resistance vs. 14% of strains without such exposure (p = 0.00085). Similar associations were not seen for other antibiotics. Macrolide use in the previous 6 months is associated with macrolide resistance in sputum isolates of S. pneumoniae. Recent antibiotic exposure may help in determining appropriate antibiotic treatment in these patients.

Comparison of transformation frequencies among selected Streptococcus pneumoniae serotypes

Although there are over 90 serotypes of Streptococcus pneumoniae, antimicrobial resistance is predominantly found in a limited number of serotypes/serogroups, namely 6, 9, 14, 19 and 23. There is no compelling mechanism to account for this restriction. We aimed to determine whether serotypes commonly associated with drug resistance have higher transformation frequencies than those that are susceptible to antimicrobial agents. An in vitro investigation of the genetic transformation frequency of drug-resistant serotypes compared with that of susceptible serotypes under the influence of synthetic competence-stimulating peptides was performed. The transforming DNA was genomic DNA carrying a Tn916-like transposon containing the mefE gene that confers resistance to erythromycin. It was observed that serotypes 6, 9, 14, 19 and 23, which are highly associated with drug resistance, do not exhibit a higher degree of transformation efficiency than other serotypes. These findings suggest that the association of serotype with drug resistance is likely due to prolonged exposure to transforming DNA resulting from longer nasopharyngeal carriage and to a greater selective pressure from antimicrobials, particularly in children. This is the first study to compare the transformation frequencies of pneumococcal clinical isolates using genomic DNA that carries the composite Tn916-like element.

Antibiotics in acute exacerbations of chronic bronchitis

Acute exacerbations of chronic bronchitis (AECB) are a major contributor to morbidity and mortality in patients with chronic obstructive pulmonary disease, accounting for more than 16 million physician office visits and over 500,000 hospitalizations in the USA each year. Antimicrobials have been recognized by clinical guidelines as an important component in the management of AECB with a bacterial etiology. The challenge of identifying patients most likely to benefit from antimicrobial therapy is difficult in the clinical setting. However, appropriate risk stratification of patients, and the use of antimicrobials within the correct spectrum and for a suitable duration, can improve clinical outcomes while minimizing induction of antimicrobial resistance. With an improved design in pharmacologic and clinical studies, differences can be appreciated among the various antimicrobial agents available to treat AECB. Factors to be considered in antimicrobial agent selection include local tissue penetration, effects on bacteriological eradication, duration of therapy, speed of resolution and prevention or delay of recurrences.

The epidemiology of pneumococcal infections--the Swedish experience

Pneumococcal infections are major contributors to morbidity and mortality world-wide and pose a major public health problem. Despite being a devastating pathogen pneumococci are common colonizers of the upper respiratory tract of healthy children. There is a need for more knowledge on the molecular epidemiology, and pathogenesis of pneumococcal infections to be able to find better strategies for prevention and treatment of these common infections. Here we discuss trends in the vaccine era of the epidemiology of pneumococcal carriage, invasive disease and antibiotic resistance development as well as present national epidemiology data from Sweden of invasive pneumococcal infections during 1987-2006.

Fosfomycin for the treatment of infections caused by Gram-positive cocci with advanced antimicrobial drug resistance: a review of microbiological, animal and clinical studies

BACKGROUND

The advancing antimicrobial drug resistance in Gram-positive cocci complicates the selection of appropriate therapy. The re-evaluation of older antibiotics may prove useful in expanding relevant therapeutic options.

OBJECTIVE

We sought to evaluate fosfomycin for the treatment of infections caused by methicillin-resistant staphylococci, vancomycin-resistant enterococci, and penicillin-non-susceptible pneumococci.

METHODS

We searched in PubMed, Scopus, and the Cochrane Library for studies evaluating the antimicrobial activity of fosfomycin against the above-mentioned pathogens, or the in vivo or clinical effectiveness of fosfomycin for the treatment of infections caused by these pathogens.

RESULTS/CONCLUSIONS

As reported in the identified studies, the susceptibility rate of methicillin-resistant Staphylococcus aureus to fosfomycin was > or = 90% in 12/22, and 50-90% in 7/22 studies; the cumulative susceptibility rate was 87.9% (4240/4892 isolates). The cumulative susceptibility rate of vancomycin-resistant enterococci to fosfomycin was 30.3% (183/604 isolates), and that of penicillin-non-susceptible pneumococci was 87.2% (191/219 isolates). Clinical data show that fosfomycin, primarily in combination regimens, has been associated with clinical success in 28/29 (96.6%) cases of infection (mainly pneumonia, bacteremia, and meningitis) by fosfomycin-susceptible isolates of methicillin-resistant S. aureus. The above data support further research on the role of fosfomycin against infections caused by Gram-positive cocci with advanced antimicrobial drug resistance.

The impact of the pneumococcal conjugate vaccine on antimicrobial resistance in the United States since 1996: evidence for a significant rebound by 2007 in many classes of antibiotics

BACKGROUND

The impact of the introduction of the pneumococcal conjugate vaccine over antimicrobial resistance has not been well established. The present study models the changes in resistance over time for all major classes of antibiotics.

METHODS

Susceptibility data on a total of 129,652 isolates from The Surveillance Network surveillance database during the period 1996-2007 were available for analysis, as well as age, specimen source, inpatient or outpatient location, and census region. Cubic splines in a logistic regression mixed model were used to model changes of the resistance rates over time in the United States, taking into account risk factors, so that separate adjusted curves were modeled for each antibiotic.

RESULTS

Yearly resistance prevalence to most antibiotics had been increasing in the period 1996-2001. Adjusted prevalence rates in a multivariate model declined in the period 2001-2004 for penicillin, erythromycin, amoxicillin/clavulanate, trimethoprim/sulfamethoxazole, tetracycline, ceftriaxone, and multidrug. These same antibiotics showed a significant rebound for the period 2004-2007, with the largest overall increase for erythromycin, followed by amoxicillin/clavulanate, tetracycline, multidrug, penicillin, trimethoprim/sulfamethoxazole, and ceftriaxone. Changes in both decline and rebound were more marked for children <5 years old and for otitis media isolates.

CONCLUSION

The indirect effect of the pneumococcal conjugate vaccine introduction on yearly resistance prevalence for several antibacterials as well as for multidrug resistance is one of blunting of a prior sustained increase, with a significant but short-lived decrease in resistance rates, and a significant rebound in adjusted rates for the period 2004-2007.

Risk factors for nasopharyngeal carriage of drug-resistant Streptococcus pneumoniae: data from a nation-wide surveillance study in Greece

Background

A nation-wide surveillance study was conducted in Greece in order to provide a representative depiction of pneumococcal carriage in the pre-vaccination era and to evaluate potential risk factors for carriage of resistant strains in healthy preschool children attending daycare centers.

Methods

A study group was organized with the responsibility to collect nasopharyngeal samples from children. Questionnaires provided demographic data, data on antibiotic consumption, family and household data, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and resistant strains were serotyped.

Results

Between February and May 2004, from a total population of 2536 healthy children, a yield of 746 pneumococci was isolated (carriage rate 29.41%). Resistance rates differed among geographic regions. Recent antibiotic use in the last month was strongly associated with the isolation of resistant pneumococci to a single or multiple antibiotics. Serotypes 19F, 14, 9V, 23F and 6B formed 70.6% of the total number of resistant strains serotyped.

Conclusion

Recent antibiotic use is a significant risk factor for the colonization of otherwise healthy children's nasopharynx by resistant strains of S pneumoniae. The heptavalent pneumococcal conjugate vaccine could provide coverage for a significant proportion of resistant strains in the Greek community. A combined strategy of vaccination and prudent antibiotic use could provide a means for combating pneumococcal resistance.

Novel type of Streptococcus pneumoniae causing multidrug-resistant acute otitis media in children

A new multidrug-resistant strain of serotype 19A has been characterized in upstate New York.

After our recent discovery of a Streptococcus pneumoniae 19A “superbug” (Legacy strain) that is resistant to all Food and Drug Administration–approved antimicrobial drugs for treatment of acute otitis media (AOM) in children, other S. pneumoniae isolates from children with AOM were characterized by multilocus sequence typing (MLST). Among 40 isolates studied, 16 (40%) were serotype 19A, and 9 (23%) were resistant to multiple antimicrobial drugs. Two others had unreported sequence types (STs) that expressed the 19A capsule, and 8 (88%) of the 9 multidrug-resistant strains were serotype 19A, including the Legacy strain with the new ST-2722. In genetic relatedness, ST-2722 belonged to a cluster of reported strains of S. pneumoniae in which all strains had 6 of the same alleles as ST-156. The multidrug-resistant strains related to ST-156 expressed different capsular serotypes: 9V, 14, 11A, 15C, and 19F.

Benefit-risk assessment of telithromycin in the treatment of community-acquired pneumonia

The purpose of this review is to assess the benefits and risks associated with the use of the ketolide antibacterial telithromycin, currently licensed for the treatment of adults with mild to moderate community-acquired pneumonia (CAP). Telithromycin is active against both the major (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) and atypical/intracellular (Chlamydophila pneumoniae, Legionella pneumophila and Mycoplasma pneumoniae) CAP pathogens. It is associated with a low potential to select for resistance and has maintained its in vitro activity against isolates of respiratory pathogens in countries where it has been in clinical use for several years. In randomized clinical trials, telithromycin has demonstrated efficacy comparable to the established antibacterial classes (macrolides, fluoroquinolones and beta-lactams) in the treatment of CAP.The safety profile of telithromycin is broadly similar to that of other antibacterials used to treat CAP. The most common adverse events are gastrointestinal adverse effects and headache; these are generally mild to moderate in severity and reversible. Telithromycin appears to be well tolerated by adult patients in all age groups, including those with co-morbid conditions. In common with other antibacterials, telithromycin has the potential to affect the corrected QT interval; the concomitant use of cisapride or pimozide with telithromycin is contraindicated, while telithromycin should be avoided in patients receiving Class IA or Class III antiarrhythmic drugs. Visual disturbances (usually transient) have occurred in a small proportion of patients treated with telithromycin; it is recommended that activities such as driving are minimized during treatment. Telithromycin is contraindicated in patients with myasthenia gravis. Hepatic dysfunction may occur in some patients taking telithromycin; rare cases of acute hepatic failure and severe liver injury, including deaths, have been reported. As telithromycin is an inhibitor of the cytochrome P450 (CYP) 3A4 system, coadministration of telithromycin with drugs metabolized by this pathway may require dose adjustments (e.g. with benzodiazepines) or a temporary hiatus in the use of the coadministered drug (e.g. HMG-CoA reductase inhibitors) metabolized by CYP3A4. Telithromycin may potentiate the effects of oral anticoagulants; careful monitoring is recommended in patients receiving telithromycin and oral anticoagulants simultaneously.Although serious and sometimes fatal events have occurred in patients receiving telithromycin therapy, current data indicate that telithromycin offers an acceptable benefit risk ratio in the treatment of mild to moderate CAP.

The British Society for Antimicrobial Chemotherapy Resistance Surveillance Project: a successful collaborative model

The British Society for Antimicrobial Chemotherapy (BSAC) Resistance Surveillance Project was initiated in light of the need for UK-wide surveillance of antibacterial resistance in key clinical pathogens. The Project comprises two defined-protocol programmes that cover a range of important pathogens and antibacterials related to community-acquired respiratory tract infection and bloodstream infection, respectively. The Respiratory Programme has reported quantitative susceptibility data for Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis collected from across the UK and Ireland since 1999. The Bacteraemia Programme has reported the susceptibility of a wide range of Gram-positive and -negative organisms since 2001. The sustainability of the Programmes relies on a unique collaborative funding model: sponsorship is provided by a number of pharmaceutical companies in return for the inclusion of their investigational or marketed agents in the study alongside a core panel of established antibacterials. The sponsors have changed over time according to their interest in participating. Results for marketed agents are communicated in a timely manner through the BSAC web site and by presentation and publication, and for investigational agents with the agreement of their sponsors. The Project satisfies the requirement for sustainable defined-protocol high-quality resistance surveillance across the UK and Ireland.

Low incidence of antibiotic resistance among invasive and nasopharyngeal isolates of Streptococcus pneumoniae from children in rural Philippines between 1994 and 2000

The purpose of this study was to determine the prevalence of acquired antimicrobial resistance in Streptococcus pneumoniae isolated from nasopharyngeal swabs and blood and cerebrospinal fluid (CSF) specimens of 3,028 children hospitalized with signs or symptoms of pneumonia, sepsis, or meningitis in rural Philippines between 1994 and 2000. Pneumococci were identified using standard methods, serotyped, and their susceptibility to oxacillin, erythromycin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole was determined using the disk diffusion method. Penicillin minimum inhibitory concentrations (MICs) of the oxacillin-resistant isolates were further tested. The clonality of the penicillin-nonsusceptible (PNSP) isolates was analyzed using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Altogether 1,048 isolates were analyzed, of which 35 were invasive and 1,013 nasopharyngeal isolates. None was resistant, but 22 (2.1%) were intermediately resistant to penicillin, 4 (0.2%) were resistant to chloramphenicol, 3 (0.2%) to erythromycin, 39 (3.7%) to tetracycline, and 4 (0.2%) to trimethoprim/sulfamethoxazole. Twelve of the 22 PNSP isolates were of serotype 14 and of sequence type 63. These included the two invasive PNSP isolates. PFGE profiling further identified three separate clusters among the sequence of type 63, serotype 14 (ST63(14)) isolates. Antimicrobial resistance in both invasive and nasopharyngeal pneumococcal pediatric isolates in rural Philippines is rare. In spite of this remote setting, the PNSP isolates of the serotype 14 clusters were of ST63 type, which has been described previously on other continents.

National and regional assessment of antimicrobial resistance among community-acquired respiratory tract pathogens identified in a 2005-2006 U.S. Faropenem surveillance study

Surveillance studies conducted in the United States over the last decade have revealed increasing resistance among community-acquired respiratory pathogens, especially Streptococcus pneumoniae, that may limit future options for empirical therapy. The objective of this study was to assess the scope and magnitude of the problem at the national and regional levels during the 2005-2006 respiratory season (the season when community-acquired respiratory pathogens are prevalent) in the United States. Also, since faropenem is an oral penem being developed for the treatment of community-acquired respiratory tract infections, another study objective was to provide baseline data to benchmark changes in the susceptibility of U.S. respiratory pathogens to the drug in the future. The in vitro activities of faropenem and other agents were determined against 1,543 S. pneumoniae isolates, 978 Haemophilus influenzae isolates, and 489 Moraxella catarrhalis isolates collected from 104 U.S. laboratories across six geographic regions during the 2005-2006 respiratory season. Among S. pneumoniae isolates, the rates of resistance to penicillin, amoxicillin-clavulanate, and cefdinir were 16, 6.4, and 19.2%, respectively. The least effective agents were trimethoprim-sulfamethoxazole (SXT) and azithromycin, with resistance rates of 23.5 and 34%, respectively. Penicillin resistance rates for S. pneumoniae varied by region (from 8.7 to 22.5%), as did multidrug resistance rates for S. pneumoniae (from 8.8 to 24.9%). Resistance to beta-lactams, azithromycin, and SXT was higher among S. pneumoniae isolates from children than those from adults. beta-Lactamase production rates among H. influenzae and M. catarrhalis isolates were 27.4 and 91.6%, respectively. Faropenem MICs at which 90% of isolates are inhibited were 0.5 mug/ml for S. pneumoniae, 1 mug/ml for H. influenzae, and 0.5 mug/ml for M. catarrhalis, suggesting that faropenem shows promise as a treatment option for respiratory infections caused by contemporary resistant phenotypes.

Distribution of resistant gram-positive organisms across the census regions of the United States and in vitro activity of tigecycline, a new glycylcycline antimicrobial

BACKGROUND

Gram-positive isolates were collected from 76 medical centers within the 9 census regions across the United States.

METHODS

Antimicrobial susceptibilities were determined according to Clinical and Laboratory Standards Institute guidelines.

RESULTS

Vancomycin resistance among Enterococcus faecium isolates varied from 45.5% (New England) to 85.3% (East South Central). The lowest concentrations at which 90% of the isolates were inhibited (MIC90) were for tigecycline (0.06-0.12 microg/mL) and for linezolid (2-4 microg/mL). Methicillin-resistant Staphylococcus aureus (MRSA) varied from 27.4% (New England) to 62.4% (East South Central). All MRSA were susceptible to tigecycline, linezolid, and vancomycin. Penicillin-nonsusceptible Streptococcus pneumoniae ranged from 23.3% in the Pacific region to 54.5% in the East South Central region. Tigecycline, imipenem, levofloxacin, linezolid, and vancomycin all maintained MIC90 of < or =1 microg/mL against penicillin-nonsusceptible S pneumoniae in vitro, irrespective of region.

CONCLUSION

This study demonstrates the variable rate of antimicrobial-resistant gram-positive organisms in the United States. Tigecycline may make a useful addition to the antimicrobial armamentarium.

Antimicrobial susceptibility and genetic characteristics of Streptococcus pneumoniae isolates indicating possible nosocomial transmission routes in a community hospital in Japan

A clinical study was designed to study Streptococcus pneumoniae isolates recovered from a community hospital in Japan from April 2001 to November 2002. A total of 73 isolates were defined as derived from inpatient, outpatient, and hospital staff groups. The MIC results showed that 20 strains (27.4%) were susceptible to penicillin G, 39 strains (53.4%) had intermediate resistance, and 14 strains (19.2%) had full resistance. Low susceptibility to macrolides was also detected: 32.9%, 32.9%, and 34.2% of all strains were resistant to erythromycin, clarithromycin, and azithromycin, respectively. Thirty strains (41%) were resistant to at least two different kinds of antibiotics. Nineteen disparate serotypes were detected besides two nontypeable strains, and the predominant serotypes were 19F and 23F. Pulsed-field gel electrophoresis (PFGE) pattern A was dominant in the serotype 19F group; this pattern was similar to that of the international clone Taiwan 19F. A total of 10 different patterns were detected in the 23F group and were distinguishable from those of the international clones Spain 23F and Taiwan 23F. Pattern b strains were identified in the same ward, and pattern d strains were found both in patients with nosocomial pneumococcal infections (NPI) and in outpatients. In conclusion, drug-resistant S. pneumoniae was spreading rapidly, especially isolates of the serotype 19F and 23F groups. PFGE data revealed interpatient transmission and suggested that there might be some association between NPI patient strains and outpatient strains.

Risk factors for development of multiple-class resistance to Streptococcus pneumoniae Strains in Belgium over a 10-year period: antimicrobial consumption, population density, and geographic location

We investigated the impact of the usage of antibiotics in ambulatory patients in Belgium in 147 defined geographical circumscriptions and at the individual isolate level. The study included 14,448 Streptococcus pneumoniae strains collected by the Belgium national reference lab from 1994 to 2004. Additional risk factors for resistance, such as population density/structure and day care attendance, were investigated for the same time-space window. A statistical model that included resistance to two or more antimicrobial classes offered the best fit for measuring the changes in nonsusceptibility to penicillin, macrolides, and tetracycline over time and place in Belgium. Analysis at the geographic level identified antimicrobial consumption with a 1-year lag (0.5% increase per additional defined daily dose) and population density as independent predictors of multiple resistance. Independent risk factors at the isolate level were age (odds ratio [OR], 1.55 for children aged <5 years), population density (7% increase in multiple resistance per 100 inhabitants/km(2)), conjugate 7-valent vaccine serotype (OR, 14.3), location (OR, 1.55 for regions bordering high-resistance France), and isolate source (OR, 1.54 for ear isolates). The expansion of multiple-resistant strains explains most of the overall twofold increase and subsequent decrease in single antimicrobial resistance between 1994 and 2004. We conclude that factors in addition to antibiotic use, such as high population density and proximity to high-resistance regions, favor multiple resistance. Regional resistance rates are not linearly related to actual antibiotic use but are linked to past antibiotic use plus a combination of demographic and geographic factors.

Microbiology and Principles of Antimicrobial Therapy for Head and Neck Infections

The principles of antimicrobial management for head and neck infections include establishing an accurate clinical and microbiologic diagnosis and treating the patient initially with an empiric antimicrobial regimen based on predicted likelihood of success and reduced potential for resistance. Subsequent adjustments may be required based on clinical response and available culture results. This article summarizes the aerobic and anaerobic microbiology of selected acute and chronic infections of the head and neck and the approaches to antimicrobial therapy.

Empirical use of antibiotics and adjustment of empirical antibiotic therapies in a university hospital: a prospective observational study

Background

Several strategies to optimise the use of antibiotics have been developed. Most of these interventions can be classified as educational or restrictive. Restrictive measures are considered to be more effective, but the enforcement of these measures may be difficult and lead to conflicts with prescribers. Any intervention should be aimed at targets with the highest impact on antibiotic prescribing. The aim of the present study was to assess the adequacy of empirical and adjusted antibiotic therapies in a Swiss university hospital where no antibiotic use restrictions are enforced, and to identify risk factors for inadequate treatment and targets for intervention.

Methods

A prospective observational study was performed during 9 months. All patients admitted through the emergency department who received an antibiotic therapy within 24 hours of admission were included. Data on demographic characteristics, diagnoses, comorbidities, systemic inflammatory response syndrome (SIRS) parameters, microbiological tests, and administered antibiotics were collected prospectively. Antibiotic therapy was considered adequate if spectrum, dose, application modus, and duration of therapy were appropriate according to local recommendations or published guidelines.

Results

2943 admitted patients were evaluated. Of these, 572 (19.4%) received antibiotics within 24 hours and 539 (94%) were analysed in detail. Empirical antibiotic therapy was inadequate in 121 patients (22%). Initial therapy was adjusted in 168 patients (31%). This adjusted antibiotic therapy was inadequate in 46 patients (27%). The main reason for inadequacy was the use of antibiotics with unnecessarily broad spectrum (24% of inadequate empirical, and 52% of inadequate adjusted therapies). In 26% of patients with inadequate adjusted therapy, antibiotics used were either ineffective against isolated pathogenic bacteria or antibiotic therapy was continued despite negative results of microbiological investigations.

Conclusion

The rate of inadequate antibiotic therapies was similar to the rates reported from other institutions despite the absence of a restrictive antibiotic policy. Surprisingly, adjusted antibiotic therapies were more frequently inappropriate than empirical therapies. Interventions aiming at improving antibiotic prescribing should focus on both initial empirical therapy and streamlining and adjustment of therapy once microbiological results become available.

A comparison of antibiotic use in children between Canada and Denmark

BACKGROUND

High rates of antibiotic prescribing in children lead to antibiotic resistance in the community. Surveillance on utilization rates and comparisons with other jurisdictions are methods for benchmarking. Surveillance on antibiotic use is well established in Europe, including Denmark, but until recently, similar data from Canada were lacking.

OBJECTIVE

To compare pediatric antibiotic prescribing rates in British Columbia, Canada, with those in Denmark.

METHODS

Population-based data on antibiotic prescriptions from British Columbia and Denmark were obtained from 1999 to 2003 for children less than 15 years of age. Annual trends in prescription rates per 1000 children were analyzed by using generalized linear models for all children less than 15 years of age; they were stratified by age group (0-4, 5-9, 10-14 y) for all antibiotics. Class-specific trends were also evaluated for penicillins, cephalosporins, macrolides, sulfonamides and trimethoprim, tetracyclines, and fluoroquinolones.

RESULTS

From 1999 to 2003, the overall British Columbia prescription rate was significantly higher than that of Denmark (p < 0.0001) at all age stratifications. In 2003, the British Columbia prescription rate was twice that of Denmark, at 608 versus 385 prescriptions per 1000 children, respectively. In both jurisdictions, the majority of antibiotics used were penicillins (Anatomical Therapeutic Chemical class J01C). However, in British Columbia, most penicillins used were extended-spectrum (83% in 2003); in Denmark, 34% of penicillins used in 2003 were extended-spectrum and 56% were beta-lactamase sensitive. In British Columbia, use of penicillins (-4.5%), cephalosporins (-5.5%), trimethoprim/sulfamethoxazole (-36%), and tetracycline (-1.6%) decreased over time, whereas in Denmark, use of penicillins increased by 11% over time and non-penicillin antibiotics remained stable. A significant increase in macrolide consumption was seen in British Columbia due to use of clarithromycin and azithromycin; in contrast, macrolide consumption declined in Denmark.

CONCLUSIONS

Compared with Denmark, the antibiotic prescription rate for children is substantially higher in British Columbia. In addition, there has been a significant increase in the use of macrolides, especially the second-generation agents, in British Columbia compared with the use in Denmark. Further studies are required to delineate reasons for antibiotic prescribing patterns in these 2 jurisdictions.

Role of oral extended-spectrum cephems in the treatment of acute exacerbation of chronic bronchitis

Risk stratification is the recommended approach for treatment of acute exacerbation of chronic bronchitis (AECB) to optimize the chances of clinical success. The suggested oral therapy for "simple or uncomplicated" AECB, which is predominantly a result of infection due to Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae, includes advanced macrolides and 2nd- or 3rd-generation cephalosporins, in addition to the older 1st-line agents (aminopenicillins, doxycycline, trimethoprim/sulfamethoxazole, and erythromycin). In light of increasing resistance of H. influenzae and S. pneumoniae to the older agents, the specific directed structural modification of the cephalosporin nucleus resulted in the development of extended-spectrum 3rd-generation oral cephems with enhanced beta-lactamase stability and improved activity against Gram-positive pathogens (penicillin-susceptible S. pneumoniae and oxacillin-susceptible Staphylococcus aureus). Analysis of results of double-blind randomized clinical trials assessing efficacy of the extended-spectrum oral cephems published since 2000 demonstrates that both cefdinir and cefditoren have similar point estimates of success in comparison to their comparators (cefuroxime, cefprozil, or Locarbacef), when either the clinical cure or the bacteriologic response was analyzed. Thus, oral extended-spectrum 3rd-generation cephems, which retain antimicrobial efficacy against the traditional respiratory pathogens despite changing resistance patterns, offer excellent coverage against the key pathogens involved in simple or uncomplicated AECB.

Streptococcus pneumononiae gyrase ATPase: development and validation of an assay for inhibitor discovery and characterization

The rise in bacterial resistance to antibiotics demonstrates the medical need for new antibacterial agents. One approach to this problem is to identify new antibacterials that act through validated drug targets such as bacterial DNA gyrase. DNA gyrase uses the energy of ATP hydrolysis to introduce negative supercoils into plasmid and chromosomal DNA and is essential for DNA replication. Inhibition of the ATPase activity of DNA gyrase is the mechanism by which coumarin-class antibiotics such as novobiocin inhibit bacterial growth. Although ATPase inhibitors exhibit potent antibacterial activity against gram-positive pathogens, no gyrase ATPase activity from a gram-positive organism is described in the literature. To address this, we developed and optimized an enzyme-coupled phosphate assay and used this assay to characterize the ATPase kinetics of Streptococcus pneumoniae gyrase. The S. pneumoniae enzyme exhibits cooperativity with ATP and requires organic potassium salts. We also studied inhibition of the enzyme by novobiocin. Apparent inhibition constants for novobiocin increased linearly with ATP concentration, indicative of an ATP-competitive mechanism. Similar binding affinities were measured by isothermal titration calorimetry. These results reveal unique features of the S. pneumoniae DNA gyrase ATPase and demonstrate the utility of the assay for screening and kinetic characterization of ATPase inhibitors.

Statewide sentinel surveillance for antibiotic nonsusceptibility among streptococcus pneumoniae isolates in South Carolina, 2003-2004

BACKGROUND

In 2003, the South Carolina Department of Health and Environmental Control established the Carolina Antibiotic Resistance Surveillance System (CARSS), an active sentinel surveillance system for antibiotic-resistant Streptococcus pneumoniae.

METHODS

CARSS includes twelve hospitals. Each hospital was assigned a weighted sample size. Minimum inhibitory concentrations were determined using the E-test method.

RESULTS

A total of 452 isolates were collected. The prevalence of penicillin nonsusceptibility in the study was 44.9%. Penicillin intermediate resistance (PCN-I) was 33.2%, and penicillin high-level resistance (PCN-R) was 11.7%. One hundred six (23.5%) isolates were nonsusceptible to one antibiotic. One hundred twenty-four (27.4%) isolates were nonsusceptible to three or more antibiotics.

CONCLUSIONS

CARSS confirmed the prevalences of antibiotic nonsusceptibility previously reported for South Carolina. However, CARSS suggests resistance is shifting from PCN-R to PCN-I in South Carolina. There is a high prevalence of multidrug nonsusceptibility in South Carolina. CARSS will continue to monitor these trends.

Tigecycline: a new glycylcycline antimicrobial

Tigecycline is a new glycyclcycline antimicrobial recently approved for use in the USA, Europe and elsewhere. While related to the tetracyclines, tigecycline overcomes many of the mechanisms responsible for resistance to this class. It demonstrates favourable in vitro potency against a variety of aerobic and anaerobic Gram-positive and Gram-negative pathogens, including those frequently demonstrating resistance to multiple classes of antimicrobials. This includes methicillin-resistant Staphylococcus aureus, penicillin-resistant S. pneumoniae, vancomycin-resistant enterococci, Acinetobacter baumannii, beta-lactamase producing strains of Haemophilis influenzae and Moraxella catarrhalis, and extended-spectrum beta-lactamase producing strains of Escherichia coli and Klebsiella pneumoniae. In contrast, minimum inhibitory concentrations for Pseudomonas and Proteus spp. are markedly elevated. Tigecycline is administered parenterally twice daily. Randomised, controlled trials have demonstrated that tigecycline is non-inferior to the comparators for the treatment of complicated skin and skin structure infections, as well as complicated intra-abdominal infections. The most frequent and problematic side effect associated with its administration to date has been nausea and/or vomiting.

Geographically-based evaluation of multidrug resistance trends among Streptococcus pneumoniae in the USA: findings of the FAST surveillance initiative (2003–2004)

Surveillance initiatives to track Streptococcus pneumoniae resistance trends are important for understanding the current in vitro effectiveness of available antimicrobial agents. The antimicrobial susceptibility profiles of S. pneumoniae (n=1479 isolates) collected from 17 geographical areas across the USA (2003-2004) were analysed; 36.8% of isolates were resistant to one or more agents (24.4% were multidrug-resistant, i.e. resistant to two or more antimicrobial classes). Multidrug resistance involved resistance to beta-lactams, macrolides, tetracycline and trimethoprim/sulphamethoxazole, but rarely fluoroquinolones (>96% of multidrug-resistant isolates were fluoroquinolone-susceptible). Multidrug resistance rates were prominent regardless of the geographical region surveyed. As this trend continues, the empirical therapeutic options for S. pneumoniae infections will diminish and there will be an ongoing need to evaluate the effectiveness of potent fluoroquinolones such as gemifloxacin.