Emergence of multidrug-resistant Streptococcus pneumoniae: report from the SENTRY Antimicrobial Surveillance Program (1999–2003)

New guidelines for the management of adult community-acquired pneumonia

PURPOSE OF REVIEW

Community-acquired pneumonia is a major cause of morbidity and mortality, and is the leading cause of death from an infectious disease. International societies have published and revised guidelines aiming to improve the management of adult community-acquired pneumonia, based on the best available evidence. The aim of this review is to compare the current guideline recommendations.

RECENT FINDINGS

Aspects of guidelines differ based on local factors including resources and antimicrobial factors, as well as the differences in interpretation of existing evidence.

SUMMARY

The lack of robust evidence behind aspects of guideline recommendations as well as the lack of adherence to published guidelines both need to be addressed if the management of community-acquired pneumonia is to be improved.

Oral β-lactams in the treatment of acute otitis media

Acute otitis media (AOM) is an important infectious disease among children throughout the world. The management of AOM is complicated by difficulties in diagnosis, spontaneous resolution, altered microbiology after pneumococcal conjugate vaccine use, and expanding antimicrobial resistance. The recent introduction of the heptavalent pneumococcal vaccine has resulted in a decrease in AOM due to penicillin-nonsusceptible strains of Streptococcus pneumoniae (PNSP) and an increase in infection due to beta-lactamase-positive nontypeable Haemophilus influenzae. The results of in vitro susceptibility testing in the context of broad surveillance programs provide useful information regarding the potency and spectrum of the oral beta-lactam antibacterial agents used in the treatment of AOM. The application of pharmacokinetic/pharmacodynamic breakpoints provides an effective means of projecting the potential clinical efficacy of the available agents. In view of what appears to be an increase prominence of beta-lactamase-positive Gram-negative AOM pathogens and a decrease in PNSP, it appears that empiric therapy for AOM should now include an agent with activity against beta-lactamase-positive H. influenzae and S. pneumoniae.

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.

Oral beta-lactams in the treatment of acute bacterial rhinosinusitis

Acute bacterial rhinosinusitis (ABRS) is a well-known complication of viral upper respiratory tract infection and is associated with a significant socioeconomic burden. Difficulties in diagnosis, a substantial spontaneous resolution rate, and growing concerns regarding antimicrobial resistance make the proper management of ABRS quite challenging. Treatment guidelines have been developed, taking into account the major bacterial pathogens, rates of antimicrobial resistance, spontaneous resolution rates, and pharmacokinetic and pharmacodynamic considerations. Optimal choices for initial treatment of ABRS in patients without prior antibacterial exposure include the oral beta-lactam agents amoxicillin/clavulanate, cefdinir, cefpodoxime, and cefuroxime. Clinicians are encouraged to consider the local pathogen distribution and rates of antibacterial resistance in selecting therapy for ABRS.

The efficacy of cefditoren pivoxil in the treatment of lower respiratory tract infections, with a focus on the per-pathogen bacteriologic response in infections caused by Streptococcus pneumoniae and Haemophilus influenzae: a pooled analysis of seven clinical trials

BACKGROUND

Community-acquired pneumonia (CAP) and acute exacerbations of chronic bronchitis (AECB) are frequently caused by Streptococcus pneumoniae, Haemopbilus influenzae, and Moraxella catarrbalis; thus, these are the target pathogens for antibiotic treatment.

OBJECTIVES

This pooled analysis was performed to evaluate the efficacy of cefditoren pivoxil (CDN) in patients with lower respiratory tract infections (CAP or AECB). A particular focus was the per-pathogen bacteriologic response rate among the most common causative pathogens, S pneumoniae, H influenzae, and M catarrbalis.

METHODS

The final reports of all clinical trials of CDN in the treatment of community-acquired lower respiratory tract infection were reviewed. Microbiologic outcome data for CDN 200 and 400 mg and comparator treatments were pooled from 4 CAP studies (3 randomized and 1 noncomparative) and 3 AECB studies. The comparators were the standard oral treatments clarithromycin 500 mg BID, cefuroxime 250 mg BID, cefpodoxime 200 mg BID, and amoxicillin/clavulanate 500/125 mg TID or 875/125 mg BID. Microbiologic response was defined as eradication of the initial pathogen or presumed eradication (absence of sputum for culture in a patient with a clinical response).

RESULTS

The bacteriologically evaluable population contained 654 patients in the CDN 200-mg group, 592 in the CDN 400-mg group, and 664 in the comparator group. A total of 1223 target pathogens were isolated before treatment: 406 isolates of S pneumoniae (including 56 penicillin-nonsusceptible [intermediate + resistant] strains), 595 isolates of H influenzae, and 222 isolates of M catarrbalis. The microbiologic response ranged from 84.1% to 88.8% in the CAP studies and from 75.1% to 77.1% in the AECB studies, with no differences between the CDN 200-mg, CDN 400-mg, and comparator groups. In the analysis of per-pathogen bacteriologic response, similar response rates were found for S pneumoniae (range, 88.5%-92.0%), H influenzae (range, 82.7%-86.6%), and M catarrbalis (range, 84.1%-95.2%), with no significant differences between groups. Focusing on penicillin-nonsusceptible (MIC >or=0.12 microg/mL) strains of S pneumoniae, CDN (both doses pooled) was associated with a response rate of 92.3% (36/39 isolates); all nonresponders were in the CDN 200-mg group. When only penicillin-resistant (MIC >or=2 microg/mL) strains were considered, there was only 1 nonresponder, again in the CDN 200-mg group. Thus, the overall response rate to CDN (both doses pooled) was 94.4% (17/18 isolates).

CONCLUSIONS

In this pooled analysis, CDN was associated with high rates of per-pathogen bacteriologic response among the main causative pathogens in lower respiratory tract infection. The rates of response were approximately 85% against H influenzae and approximately 90% against S pneumoniae, including penicillin-intermediate and penicillin-resistant strains.

Serotype and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from Taiwanese children: comparison of nasopharyngeal and clinical isolates

This report describes the serotypes and antimicrobial resistance patterns of 860 strains of Streptococcus pneumoniae isolated from nasopharyngeal (NP) carriers and clinical specimens collected from Taiwanese children during the years 1997 to 2003. The 6 most common serotypes/groups were 23F, 19F, 6B, 14, 6A, and 3. These accounted for 652/716 (91.1%) of the NP and 131/144 (91.0%) of the clinical isolates. Serotype 23F was the most common isolate in the NP carriers (25.7%, 184/716). Serogroup14 was most common in the clinical isolates (29.2%, 42/144) and the most frequent invasive isolate (43.4%, 33/76). It was more frequently associated with invasive infection than all other serotypes/groups (odds ratio = 7.2; 95% confidence interval, 4.16-12.46; P < .0001). Resistance to macrolides was high in all serotypes/groups, which ranged from 70% to 97%. Resistance to penicillin varied among the 6 leading serotypes/groups, ranging from 3% in serogroup 3 to 99% in serotype 19F. Serotype 23F was most likely to be multidrug resistant to penicillin, macrolides, and chloramphenicol compared with all others (107/150 [71%] versus 105/461 [23%], P < .0001). The potential coverage by the pentavalent and heptavalent vaccines was 83% for all isolates, but was significantly lower for NP than clinical isolates (81% versus 92%, P< .01). These findings provide baseline data to compare trends in the distribution of pneumococcal serotypes and antibiotic resistance patterns with the introduction of childhood pneumococcal vaccination in Taiwan and other countries.

World Wide Web resources on antimicrobial resistance

Advances of modern technology, including the development of the Internet and the World Wide Web, have given clinicians and researches the opportunity to have immediate access to continuously updated information in various scientific fields. We compiled a list of World Wide Web resources of data from surveillance studies on antimicrobial resistance that may be useful to practitioners--especially infectious diseases specialists--as well as to scientists with a research interest in the field of antimicrobial resistance.