Antimicrobial resistance of Streptococcus pneumoniae isolated in Taiwan: an island-wide surveillance study between 1996 and 1997

Biological and Epidemiological Features of Antibiotic-Resistant Streptococcus pneumoniae in Pre- and Post-Conjugate Vaccine Eras: a United States Perspective

Streptococcus pneumoniae inflicts a huge disease burden as the leading cause of community-acquired pneumonia and meningitis. Soon after mainstream antibiotic usage, multiresistant pneumococcal clones emerged and disseminated worldwide. Resistant clones are generated through adaptation to antibiotic pressures imposed while naturally residing within the human upper respiratory tract. Here, a huge array of related commensal streptococcal strains transfers core genomic and accessory resistance determinants to the highly transformable pneumococcus. β-Lactam resistance is the hallmark of pneumococcal adaptability, requiring multiple independent recombination events that are traceable to nonpneumococcal origins and stably perpetuated in multiresistant clonal complexes. Pneumococcal strains with elevated MICs of β-lactams are most often resistant to additional antibiotics. Basic underlying mechanisms of most pneumococcal resistances have been identified, although new insights that increase our understanding are continually provided. Although all pneumococcal infections can be successfully treated with antibiotics, the available choices are limited for some strains. Invasive pneumococcal disease data compiled during 1998 to 2013 through the population-based Active Bacterial Core surveillance program (U.S. population base of 30,600,000) demonstrate that targeting prevalent capsular serotypes with conjugate vaccines (7-valent and 13-valent vaccines implemented in 2000 and 2010, respectively) is extremely effective in reducing resistant infections. Nonetheless, resistant non-vaccine-serotype clones continue to emerge and expand.

Pneumococcal disease and use of pneumococcal vaccines in Taiwan

The use of pneumococcal vaccine plays an important role for prevention of invasive pneumococcal disease (IPD). However, introducing the pneumococcal vaccine into the national immunization program (NIP) is complex and costly. The strategy of progressively integrating the pneumococcal conjugate vaccine (PCV) into the NIP in Taiwan provides valuable experience for policy makers. The 7-valent PCV (PCV7) was first available in Taiwan in late 2005. PCV7 was first provided free to children with underlying diseases, those in vulnerable socioeconomic status, and those with inadequate health care resources. The catch-up immunization program with the 13-valent PCV was launched in 2013 and the national pneumococcal immunization program was implemented in 2015. Children aged 2-5 years had the highest incidence of IPD among pediatric population in Taiwan. Although the incidence of IPD caused by PCV7 serotypes has declined, the overall incidence of IPD remained high in the context of PCV7 use in the private sector. A surge of IPD caused by serotype 19A occurred, accounting for 53.6% of IPD cases among children aged ≤ 5 years in 2011-2012. After the implementation of the national pneumococcal immunization program, serogroup 15 has become the leading serogroup for IPD in children. Continued surveillance is necessary to monitor the serotype epidemiology in Taiwan.

Bacterial etiology of acute otitis media in the era prior to universal pneumococcal vaccination in Taiwanese children

BACKGROUND

Acute otitis media (AOM) is one of the most frequent bacterial infections in children. Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are the two major bacterial pathogens. Pneumococcal conjugate vaccine was introduced into Taiwan in 2005 and only some children were vaccinated. This retrospective study assessed the bacterial etiology of AOM and its antimicrobial susceptibility in the era prior to universal pneumococcal vaccination in Taiwan.

METHODS

From December 2009 to November 2011, children presenting with AOM and having a middle ear effusion sample collected by tympanocentesis were enrolled. The study period was divided into two parts. Demographic data of patients and antibiotic susceptibility of the pathogens were collected and analyzed. Serotypes of S. pneumoniae were identified.

RESULTS

Among the 151 episodes, 46% of samples found bacterial pathogens. S. pneumoniae and NTHi were the leading causes of AOM, detected in 55.7% and 22.9% of bacterial AOM episodes, respectively. The prevalent serotypes of S. pneumoniae were 19 A and 19 F. Significantly more pneumococcal and serotype 19 A AOM were found in the later study period (18.4% vs. 33.3%, p = 0.0036; 10.5% vs. 24.0%, p = 0.028). Among the 39 S. pneumoniae isolates, 11 strains (28.2%) were penicillin-susceptible. Of the 16 NTHi, 10 (62.5%) were susceptible to amoxicillin/clavulanate and all were susceptible to cefotaxime.

CONCLUSION

S. pneumoniae and NTHi were the leading causes of AOM in Taiwanese children in the study period. An increase in patient numbers and proportion of pneumococcal and serotype 19 A AOM occurred. Antimicrobial nonsusceptibility was common in the predominant pathogens.

Regional epidemiology of invasive pneumococcal disease in Asian adults: epidemiology, disease burden, serotype distribution, and antimicrobial resistance patterns and prevention

OBJECTIVES

To summarize published data on the clinical and economic burden, epidemiology, antimicrobial resistance levels, serotype prevalence, and prevention strategies for pneumococcal disease among adults in Asia.

METHODS

We performed a systematic search of the PubMed database for relevant, peer-reviewed articles published between January 1995 and December 2011, covering China, Hong Kong, India, Indonesia, Japan, Malaysia, Pakistan, the Philippines, Singapore, South Korea, Taiwan, Thailand, and Vietnam.

RESULTS

Taiwan and Thailand had the most comprehensive epidemiological data on adult pneumococcal disease. Very little relevant data were found for Indonesia, Pakistan, the Philippines, and Vietnam; surveillance is urgently needed in these countries. The emergence and spread of resistance emphasize the importance of vaccination to prevent infection in adults at increased risk for serious pneumococcal disease. Vaccination policies and opinions on the efficacy of vaccination vary widely in Asian countries, although a new option in the form of a pneumococcal conjugate vaccine is now available.

CONCLUSIONS

Increased awareness of the public health and economic benefits of pneumococcal vaccination is critically needed to help both the public and policymakers in making changes to vaccination policies in the region. Maximizing access to pneumococcal vaccines will decrease the number of hospitalizations, complications, and deaths associated with pneumococcal disease.

Updated antibiotic resistance and clinical spectrum of infections caused by Streptococcus pneumoniae in Taiwan: Emphasis on risk factors for penicillin nonsusceptibilities

BACKGROUND/PURPOSE(S)

Streptococcus pneumoniae is one of the leading pathogens causing community-acquired infection with high mortality rates in elderly patients. Emerging antibiotic resistance was found in past decades. Continuous surveillance to monitor changes in antibiotic resistance of S. pneumoniae and associated risk factors are important clinical issues.

METHODS

Isolates of S. pneumoniae collected from six hospitals participating in the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program III (2002) - VI (2008) were enrolled in this study. Bacterial susceptibilities were determined by minimum inhibitory concentration. The clinical data of source patients were collected retrospectively.

RESULTS

A total of 330 nonduplicate S. pneumoniae isolates were enrolled in this study. Sputum was the most common specimen source, followed by pus. The mean age of the source patients was 38 years among these 330 patients, and 247 had various infections caused by S. pneumoniae. The overall in-hospital mortality rate was 6% and most (60%)of the mortality occurred in patients older than 65 years. The mortality rates among the patients age 65 years and older and those age 5 years and younger were 12.9% (9 of 70) and 2.4% (2 of 83), respectively. The rates of nonsusceptibility to penicillin by the meningitis criteria (PNSP-M) were 69.0% in 2002, 81.0% in 2004, 73.7% in 2006, and 74.5% in 2008. Resistance to erythromycin and trimethoprim/sulfamethoxazole remained high. Using multivariate analysis, patients with PNSP isolates were more likely to have a history of antibiotic exposure within the previous 15 days compared with patients with penicillin-susceptible (PSSP) isolates (nonmeningitis criteria: 29.70% vs. 18.34%, p = 0.0288; meningitis criteria: 25.30% vs. 9.88%, p = 0.006). Shock at presentation was the risk factor for in-hospital mortality.

CONCLUSION

Our study demonstrated that the rates of penicillin nonsusceptibility among S. pneumoniae remained high in Taiwan during the study period. Previous antibiotic exposure was the only risk factor for subsequent acquisition of penicillin- nonsusceptible S. pneumoniae compared with penicillin-susceptible S. pneumoniae. Judicious antibiotic use is important to control the spread of drug nonsusceptible S. pneumoniae.

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100-200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6-200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.

Host and microbiologic factors associated with mortality in Taiwanese children with invasive pneumococcal diseases, 2001 to 2006

We concurrently evaluated host- and organism-related factors in determining the outcomes of 160 invasive pneumococcal diseases episodes in 158 Taiwanese children during 2001 and 2006. Most (138/160, 86.2%) episodes occurred at age less than 60 months, and an underlying condition was present in 35 (22.2%) cases. Common disease syndromes included complicated pneumonia (29.4%), uncomplicated pneumonia (29.4%), occult bacteremia (17.5%), and meningitis (14.4%). Mortality (13/160, 8.1%) was associated with age less than 24 months, underlying conditions, meningitis, cytopenia, intensive care, and penicillin MIC >or=2 microg/mL in univariate analysis. Pneumococcal serotypes, genotypes, origin of infections, and discordant therapy did not influence the outcome. Multivariate analysis determined the presence of underlying conditions (adjusted odds ratio [OR], 30.5; 95% confidence interval [CI], 4.8-193.1) and penicillin MIC >or=2 microg/mL (adjusted OR, 8.1; 95% CI, 1.4-47.3), which are the independent predictors for fatality. This finding highlighted the importance of immunization of disadvantaged children, targeting drug-resistant pneumococci.

Antibody responses to pneumococcal polysaccharide vaccine in Taiwanese patients with chronic obstructive pulmonary disease

BACKGROUND/PURPOSE

A study was undertaken to assess the antibody responses to a 23-valent pneumococcal polysaccharide vaccine and clinical outcome in Taiwanese patients with chronic obstructive pulmonary disease (COPD).

METHODS

From January to December 1999, 80 Taiwanese patients with COPD were enrolled. Each patient received a 23-valent pneumococcal polysaccharide vaccine (Pneumovax 23). Specific IgG antibodies to pneumococcal capsular antigens of serotypes 4, 6B, 7F, 9V, 14, 18C, 19F, and 23F were measured before vaccination, and 6 weeks and 52 weeks after vaccination.

RESULTS

Detectable prevaccination IgG antibody (> 1 microg/mL) was found in the range of 27.5% of patients for serotype 7F to 96.2% for serotype 14. Antibody concentrations in prevaccination sera were not different between middle-aged (< 65 years old) and elderly patients (> or = 65 years old). The percentage of elderly patients with postvaccination antibody concentration > 2 -fold higher than that prior to vaccination ranged from 84% for serotype 18C to 90% for serotypes 7F, 9V, and 19F. The change in antibody level (fold and absolute increases) postvaccination was not significantly different among the different age groups.

CONCLUSION

Taiwanese elderly adults with COPD, even in advanced age, can mount a significant antibody response to pneumococcal polysaccharide vaccine. This study may support the existing recommendation that pneumococcal vaccine be offered to persons > or = 65 years old with COPD.

Antimicrobial resistance patterns and serotype distribution of invasive Streptococcus pneumoniae isolates from children in Taiwan from 1999 to 2004

Streptococcus pneumoniae causes substantial morbidity and mortality worldwide. Because only limited data are available for the antibiotic resistance patterns and seroepidemiology of invasive S. pneumoniae isolates in Taiwanese children, this national surveillance of invasive pneumococcal infections in children was conducted during a 5-year period. Invasive isolates of S. pneumoniae were obtained from sterile sites (yielding blood and cerebrospinal, pleural, and intra-articular fluids) in children (aged < or =14 years) at a total of 40 regional hospitals and medical centers distributed throughout Taiwan. The collection period was between July 1999 and June 2004, with a total of 286 isolates (including 30 cerebrospinal fluids) collected. All the samples were sent to the Center for Disease Control in Taipei for serotyping and susceptibility testing. Of the 286 S. pneumoniae isolates studied, the 5 most common serotypes were 14 (28.3%), 23F (21.0%), 6B (17.1%), 19F (13.6%), and 3 (4.9%). Intermediate- and high-level penicillin resistance was determined for 50.7% and 25.5% of the isolates, respectively. Isolate resistance was demonstrated to erythromycin (93%), tetracycline (82.2%), trimethoprim/sulfamethoxazole (79.4%), cefotaxime (11.2%), and levofloxacin (0.3%). Multiple drug resistance was found for each serotype, but mostly in types 14, 23F, 6B, and 19F. Overall, 85.0% of the serotypes, 90.8% of the penicillin-nonsusceptible S. pneumoniae (PNSSP), and 90.1% of the multiple drug-resistant (MDR) isolates were covered by the heptavalent pneumococcal conjugated vaccine (PCV7). In this study, we found a diverse pulse-field gel electrophoresis pattern among MDR isolates: a high prevalence of drug resistance and a continued increasing trend in penicillin resistance among nationwide pneumococcal isolates from children in Taiwan. The highest prevalence of invasive pneumococcal disease was in children aged 2 to 5 years, and the highest PNSSP prevalence and highest PCV7 coverage were in children aged <2 years. In terms of reducing the risk of invasive pneumococcal illness in Taiwan, the use of PCV7 is likely to have a beneficial effect similar to that obtained in countries that have used it.

Adult Streptococcus pneumoniae meningitis in Southern Taiwan: epidemiologic trends and prognostic factors

The clinical features of 22 adult patients with Streptococcus pneumoniae meningitis, retrospectively collected over a 16-year period, were reviewed. Otopharyngeal infection, haematogenous spread and cranial neurosurgery continue to be the predominant routes of infection. Most patients acquired the infection in the community, and predisposing underlying conditions are common. The proportion of S. pneumoniae meningitis compared to all microorganisms causing meningitis in adults declined dramatically from 17% in the first 8 study years to 4% in the last 8 study years. However, all penicillin-resistant S. pneumoniae strains were found in the second half of the study period, accounting for 25% of these episodes. The overall mortality rates for the first and second halves of the study period were 43% and 63%, respectively. Third-generation cephalosporins were the antibiotics of choice for the treatment of S. pneumoniae meningitis in this study, however, the emergence of resistant strains may create a therapeutic challenge in the future. To avoid treatment failure, early diagnosis, careful monitoring of the clinical course and the choice of appropriate antibiotics according to the in vitro antimicrobial susceptibilities, are necessary.

The significance of seizures and other predictive factors during the acute illness for the long-term outcome after bacterial meningitis

BACKGROUND

Seizures are important neurological complications of bacterial meningitis, but no information about its epidemiology and the outcomes of seizures after community-acquired bacterial meningitis (CABM) in an adult population have been reported.

AIMS

To determine the frequency, clinical relevance, subtypes of seizures during the acute phase of bacterial meningitis, and the long-term outcomes of seizure complicating adult CABM.

METHODS

In this 12-year retrospective study, 117 adult patients were identified with culture-proven CABM. A comparison was made between the clinical data of the patients with and without seizures during hospitalization.

RESULTS

Thirty-one patients had seizures during CABM, accounting for 27% (31/117) of the episodes. The time interval between the onset of bacterial meningitis and the seizures was 1-21 days (mean, 4 days). Furthermore, 80% (25/31) of the episodes occurred within 24 h of presentation. Ten patients who had seizures progressed to status epilepticus. At follow-up after completing treatment, 10 patients completely recovered and were seizure-free, 19 died of meningitis during the acute stage and the other two progressed to chronic epilepsy.

CONCLUSION

A log-rank test demonstrated that the long-term outcome of adult CABM with acute seizures produced worse outcomes than for those who had no seizures, though no difference was noted between focal and generalized seizures. None of our patients without seizures in the acute phase of bacterial meningitis developed late seizures during the follow-up periods. Poor outcome in this study may attribute to neurological complications such as seizure, hydrocephalus, infection itself, or a combination of complications.

General and URTI-specific antibiotic prescription rates in a Malaysian primary care setting

Antibiotic prescribing by primary care doctors has received renewed interest due to the continuing emergence of antibiotic resistance and the attendant cost to healthcare. We examined the antibiotic prescribing rate in relation to selected socio-demographic characteristics of the prescribers at the Seremban Health Clinic, a large public primary care clinic, designated for teaching, in the state of Negeri Sembilan, Malaysia. Data were obtained from: (1) retrospective review of prescriptions for the month of June 2002 and (2) a questionnaire survey of prescribers. A total of 10667 prescriptions were reviewed. The overall antibiotic prescribing rate was 15%; the rate (16%) was higher for the general Outpatient Department (OPD) than the 3% for the Maternal & Child Health Clinic (MCH). The antibiotic prescription rates for upper respiratory tract infection (URTI) were 26% and 16%, respectively, for the OPD and MCH. Half of all the antibiotic prescriptions were for URTI making prescribing for URTI an appropriate target for educational intervention. The URTI-specific antibiotic prescription rate did not correlate with the prescribers' intention to specialise, patient load, perceived patient's expectation for an antibiotic, or the score for knowledge of streptococcal tonsillitis. Prescribing behaviours and record-keeping practices requiring correction were identified.

The status of antimicrobial resistance in Taiwan among Gram-positive pathogens: the Taiwan Surveillance of Antimicrobial Resistance (TSAR) programme, 2000

In the Taiwan Surveillance of Antimicrobial Resistance programme, isolates were collected from 21 hospitals over a 3-month period in 2000 (TSAR II) and rates of resistance in Gram-positive pathogens were determined. Resistance rates were high including oxacillin resistance in Staphylococcus aureus (60%) and coagulase-negative staphylococci (80%), high-level gentamicin resistance (HLGR) in Enterococcus faecalis (60%) and penicillin non-susceptibility in Streptococcus pneumoniae (69%). Oxacillin resistance had increased from 1998 (TSAR I) and may be spreading into outpatient settings. In contrast, less than 2% enterococci were vancomycin-resistant. No linezolid resistance was found in either staphylococci or enterococci.

In vitro susceptibility of six fluoroquinolones against invasive Streptococcus pneumoniae isolated from 1996 to 2001 in Taiwan

A total of 331 invasive nonduplicated Streptococcus pneumoniae isolates from three sampling periods during 1996 to 2001 were tested for susceptibility to recently developed fluoroquinolones. Five major serotypes, 23F, 6B, 14, 19F, and 3, were frequently encountered in this collection. Penicillin nonsusceptible isolates constituted 52.9% from 1996 to 1997, 61.6% from 1998 to 1999, and 60.0% from 2000 to 2001. Fifty-seven percent of the isolates were susceptible to cefotaxime, 56.5% to ceftriaxone, 54.1% to cefepime, and 52.6% to cefuroxime. Macrolide-susceptible isolates constituted less than 14% of the total sample, and no vancomycin-resistant isolates were detected. For fluoroquinolones, MIC90 was lowest for gemifloxacin (MIC90 = < or = 0.12 microg/ml), followed by moxifloxacin (MIC90 = 0.25 microg/ml), gatifloxacin (MIC90 = 0.5 microg/ml), sparfloxacin (MIC90 = 0.5 microg/ml), levofloxacin (MIC90 = 1 microg/ml), and ciprofloxacin (MIC90 = 2 microg/ml). All isolates were susceptible to sparfloxacin, levofloxacin, gatifloxacin, and gemifloxacin apart from one isolate (0.3%), which was simultaneously resistant to sparfloxacin, levofloxacin, and gatifloxacin. Mutations at the positions S81F of GyrA and D435N and I460V of ParC were detected for this multiple drug resistant isolate. The in vitro results suggest that recently developed fluoroquinolones are very effective against invasive S. pneumoniae isolates in Taiwan. Nevertheless, emerging fluoroquinolone resistance should be acknowledged and clinicians alerted. Surveillance should be carried out to monitor any changes in antibiotic resistance of S. pneumoniae.

Telithromycin- and fluoroquinolone-resistant Streptococcus pneumoniae in Taiwan with high prevalence of resistance to macrolides and beta-lactams: SMART program 2001 data

There is a high prevalence of beta-lactam- and macrolide-resistant Streptococcus pneumoniae in Taiwan. To understand the in vitro susceptibilities of recent isolates of S. pneumoniae to fluoroquinolones and telithromycin (which is not available in Taiwan), the MICs of 23 antimicrobial agents for 936 clinical isolates of S. pneumoniae isolated from different parts of Taiwan from 2000 to 2001 were determined by the agar dilution method. Overall, 72% of isolates were not susceptible to penicillin (with 61% being intermediate and 11% being resistant) and 92% were resistant to erythromycin. Telithromycin MICs were >or=1 microg/ml for 16% of the isolates, and for 99% of these isolates the MICs of all macrolides tested were >or=256 microg/ml; all of these isolates had the constitutive macrolide-lincosamide-streptogramin B phenotype. Eighty-eight percent of the isolates were resistant to three or more classes of drugs. The ciprofloxacin MICs were >or=4 microg/ml for six (0.6%) isolates from five patients collected in 2000 and 2001, and the levofloxacin MICs were >or=8 microg/ml for five of these isolates. Seven isolates for which ciprofloxacin MICs were >or=4 microg/ml, including one isolate recovered in 1999, belonged to three serotypes (serotype 19F, five isolates; serotype 23A, one isolate; and serotype 23B, one isolate). The isolates from the six patients for which ciprofloxacin MICs were >or=4 microg/ml had different pulsed-field gel electrophoresis profiles and random amplified polymorphic DNA patterns, indicating that no clonal dissemination occurred over this time period. Despite the increased rate of fluoroquinolone use, the proportion of pneumococcal isolates for which ciprofloxacin MICs were elevated (>or=4 microg/ml) remained low. However, the occurrence of telithromycin resistance is impressive and raises concerns for the future.

Epidemiology of invasive pneumococcal infection in Taiwan: antibiotic resistance, serogroup distribution, and ribotypes analyses

From July, 1998, to June, 1999, pneumococcal isolates from 288 patients with invasive disease in Taiwan were serogrouped and tested for their susceptibility to various antibiotics. Automated ribotyping was used to study their molecular epidemiology. The mortality rate among those > or = 65 years was higher than those 18 or 19-64 years (p < 0.001). The total incidence of infection was significantly higher during the cooler season than the warmer season (p = 0.017). Among strains isolated from children aged < or = 18 years, 76% were not susceptible to penicillin, a rate that was significantly higher (p < 0.001) than that for adults (45%), as was the susceptibility to azithromycin, erythromycin, and trimethoprim-sulfamethoxazole (p < 0.005). The most prevalent serogroup encountered in the invasive isolates was 23, followed by 6, 14, 19, and 3. Isolation of Streptococcus pneumoniae in cerebrospinal fluid was at high rate in children under 5 years (p = 0.00012). Molecular typing revealed a high degree of polymorphism among the isolates. Among serogroup 23 and 19 isolates, a high proportion had the same ribotypes, the Taiwan23F-15 and Taiwan19F-14 isolates, suggesting the circulation of a Taiwanese epidemic strain. In Taiwan, S. pneumoniae isolates should be tested for their resistance profile for children < or = 18 years old, as these are more likely to harbor high-level resistance. Control of pneumococcal infection with the 7-valent-conjugated vaccine should also be considered because it is estimated that it would cover nearly 90% of the serotypes among pediatric invasive disease.

Surveillance of resistance in bacteria causing community-acquired respiratory tract infections

Bacterial resistance to antibiotics in community-acquired respiratory tract infections is a serious problem and is increasing in prevalence world-wide at an alarming rate. Streptococcus pneumoniae, one of the main organisms implicated in respiratory tract infections, has developed multiple resistance mechanisms to combat the effects of most commonly used classes of antibiotics, particularly the beta-lactams (penicillin, aminopenicillins and cephalosporins) and macrolides. Furthermore, multidrug-resistant strains of S. pneumoniae have spread to all regions of the world, often via resistant genetic clones. A similar spread of resistance has been reported for other major respiratory tract pathogens, including Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. To develop and support resistance control strategies it is imperative to obtain accurate data on the prevalence, geographic distribution and antibiotic susceptibility of respiratory tract pathogens and how this relates to antibiotic prescribing patterns. In recent years, significant progress has been made in developing longitudinal national and international surveillance programs to monitor antibiotic resistance, such that the prevalence of resistance and underlying trends over time are now well documented for most parts of Europe, and many parts of Asia and the Americas. However, resistance surveillance data from parts of the developing world (regions of Central America, Africa, Asia and Central/Eastern Europe) remain poor. The quantity and quality of surveillance data is very heterogeneous; thus there is a clear need to standardize or validate the data collection, analysis and interpretative criteria used across studies. If disseminated effectively these data can be used to guide empiric antibiotic therapy, and to support-and monitor the impact of-interventions on antibiotic resistance.

Antimicrobial resistance in Streptococcus pneumoniae, Taiwan

Taiwan has one of the highest levels of antibiotic-resistant pneumococcus in the world. Pneumococcal isolates not susceptible to penicillin first appeared in Taiwan in 1986; in 1995 an increase in the prevalence of nonsusceptibility to penicillins, extended-spectrum cephalosporins, trimethoprim-sulfamethoxazole, and macrolides as well as multidrug resistance began to be recognized. With the persistence of antibiotic selective pressure, resistance in some antibiotics reached a high plateau (beta-lactam antibiotics) or continued to increase (macrolides), while novel resistance (fluoroquinolones) emerged in the last 3 years. Widespread distribution of some novel resistant 23F and 19F clones (and the international epidemic of 23F clones) contributes further to the rapid increase of resistance. Because Streptococcus pneumoniae is a major pathogen that causes community-acquired lower respiratory tract infections and meningitis in adults and children, antibiotic-resistance in this organism is a serious problem.

Emergence in Vietnam of Streptococcus pneumoniae resistant to multiple antimicrobial agents as a result of dissemination of the multiresistant Spain(23F)-1 clone

Surveillance for Streptococcus pneumoniae resistant to penicillin and other antimicrobial agents is necessary to define the optimal empirical antibiotic therapy for meningitis in resource-poor countries such as Vietnam. The clinical and microbiological features of 100 patients admitted to the Centre for Tropical Diseases in Ho Chi Minh City, Vietnam, between 1993 and 2002 with invasive pneumococcal disease were studied. A penicillin-nonsusceptible pneumococcus (MIC, > or =0.1 micro g/ml) was isolated from the blood or cerebrospinal fluid of 8% of patients (2 of 24) between 1993 and 1995 but 56% (20 of 36) during 1999 to 2002 (P < 0.0001). Pneumococcal isolates resistant to penicillin (MIC, > or =2.0 micro g/ml) increased from 0% (0 of 24) to 28% (10 of 36) (P = 0.002). Only one isolate was ceftriaxone resistant (MIC, 2.0 micro g/ml). Penicillin-nonsusceptible pneumococci were isolated from 78% of children younger than 15 years (28 of 36) compared with 25% of adults (16 of 64) (P = 0.0001). Isolation of a penicillin-nonsusceptible pneumococcus in adults with meningitis was independently associated with referral from another hospital (P = 0.005) and previous antibiotic therapy (P = 0.025). Multilocus sequence typing showed that 86% of the invasive penicillin-resistant pneumococcus isolates tested (12 of 14) were of the Spain(23F)-1 clone. The serotypes of >95% of the penicillin-nonsusceptible pneumococci were included in the currently available pneumococcal vaccines. Our findings point to the recent introduction and spread of the Spain(23F)-1 clone of penicillin-resistant pneumococci in Vietnam. Simple clinical predictors can be used to guide empirical antibiotic therapy of meningitis. Pneumococcal vaccination may help to control this problem.

The burden of invasive pneumococcal disease and the potential for reduction by immunisation

Streptococcus pneumoniae causes invasive disease world-wide and in all age groups. The reported incidence varies geographically and is increased in certain population groups. The incidence is highest in children less than 2 years and is also increased in the elderly. Mortality remains substantial even in the developed world despite appropriate antimicrobial therapy. The emergence of penicillin-resistant pneumococci highlights the importance of immunisation as a means to prevent disease. This review discusses the burden of invasive pneumococcal disease, identifies high-risk patients and analyses evidence for vaccine efficacy and cost-effectiveness.

Current status of antimicrobial resistance in Taiwan

While some trends in antimicrobial resistance rates are universal, others appear to be unique for specific regions. In Taiwan, the strikingly high prevalence of resistance to macrolides and streptogramin in clinical isolates of gram-positive bacteria correlates with the widespread use of these agents in the medical and farming communities, respectively. The relatively low rate of enterococci that are resistant to glycopeptide does not parallel the high use of glycopeptides and extended-spectrum beta-lactams in hospitals. The evolving problem of extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates is substantial, and some unique enzymes have been found. Recently, some gram-negative bacteria (e.g., Pseudomonas aeruginosa and Acinetobacter baumannii) that are resistant to all available antimicrobial agents including carbapenems have emerged.

Risk factors for acquisition of levofloxacin-resistant Streptococcus pneumoniae: a case-control study

A case-control study was conducted to identify the risk factors associated with levofloxacin-resistant Streptococcus pneumoniae (LRSP) colonization or infection. Twenty-seven case patients (patients with LRSP) were compared with 54 controls (patients with levofloxacin-susceptible S. pneumoniae). Risk factors that were significantly associated with LRSP colonization or infection, according to univariate analysis, included an older age (median age, 75 years for case patients versus 72.5 years for controls), residence in a nursing home (odds ratio [OR], 7.2), history of recent (OR, 4.6) and multiple (OR, 4.4) hospitalizations, prior exposure to fluoroquinolones (OR, 10.6) and beta-lactams (OR, 8.6), presence of chronic obstructive pulmonary disease (COPD; OR, 5.9), and nosocomial origin of the bacteria (OR, 5.7). Multivariate analysis showed that presence of COPD (OR, 10.3), nosocomial origin of the bacteria (OR, 16.2), residence in a nursing home (OR, 7.4), and exposure to fluoroquinolones (OR, 10.7) were independently associated with LRSP colonization or infection. Thus, a distinct group of patients with COPD is the reservoir of LRSP.

Changing Epidemiology of Bacterial Meningitis in the United States

Bacterial meningitis is an important cause of morbidity and mortality in the United States and throughout the world. Over the past 20 years, there have been significant changes in the epidemiology of bacterial meningitis. The most important change is the decrease in the frequency of Haemophilus influenzae type b as the most common etiologic agent of bacterial meningitis, since the H. influenzae type b conjugate vaccine was introduced. Streptococcccus pneumoniae is now the major cause of bacterial meningitis in the US and bacterial meningitis is now a disease predominantly of adults, rather than of infants and children. Emergence of antimicrobial resistance in S. pneumoniae has also altered the approach to antimicrobial therapy in patients with pneumococcal meningitis, indicating the need to use preventive strategies to reduce the frequency of this serious infection. Recent licensure of the heptavalent pneumococcal conjugate vaccine will likely decrease the overall incidence of pneumococcal meningitis.

A randomized controlled trial of azithromycin and amoxycillin/clavulanate in the management of subacute childhood rhinosinusitis

OBJECTIVE

Subacute childhood rhinosinusitis is a disorder commonly seen in children with allergic rhinitis. Antibiotics have been recommended as a major component of the treatment regime. The objective of the present study was to compare the effectiveness of a 3-day course of azithromycin and a 2-week course of amoxycillin/clavulanate in the treatment of subacute childhood rhinosinusitis.

METHODOLOGY

A randomized single-blinded control study of subacute rhinosinusitis was conducted, comparing a 3-day course of azithromycin and a 2-week course of amoxycillin/clavulanate. Inclusion criteria were children aged between 5 and 16 years, duration of nasal blockage or discharge between 30 and 120 days, and abnormal sinus radiographs. All enrolled children were prescribed budesonide nasal spray (Rhinocort Aqua Nasal Spray, Astra Pharmaceuticals, Sodertalje, Sweden) as adjuvant treatment.

RESULTS

Forty-two children were recruited into the study and one defaulted on follow-up. Failure occurred in 6 of 20 for the azithromycin group and 5 of 21 for the amoxycillin/clavulanate group. The odds ratio was 1.46 (95%CI 0.37-5. 80, P = 0.73). No relapse occurred in azithromycin group and 5 of 21 in amoxycillin/clavulanate group. The odds ratio was 0.16 (95%CI 0. 017-1.51, P = 0.18). Both antibiotics were well tolerated, however, two children, one from each group, complained of mild transient epigastric discomfort.

CONCLUSIONS

This small study did not provide evidence of a difference between 14 days of amoxycillin/clavulanate and 3 days of azithromycin. Larger studies will be needed to determine which, if any, antibiotic regimen should be used in treating subacute childhood rhinosinusitis.