Pneumococcal resistance to beta-lactam antibiotics: a global geographic overview

Guideline-Concordant Therapy for Community-Acquired Pneumonia in the Hospitalized Population: A Systematic Review and Meta-analysis

Background

A commonly used guideline for community-acquired pneumonia (CAP) is the joint American Thoracic Society and Infectious Diseases Society of America practice guideline. We aimed to investigate the effect of guideline-concordant therapy in the treatment of CAP.

Methods

We systematically searched MEDLINE, Embase, CENTRAL, Web of Science, and Scopus from 2007 to December 2023. We screened citations, extracted data, and assessed risk of bias in duplicate. Primary outcomes were mortality rates, intensive care unit (ICU) admission, and length of stay. Secondary outcomes were guideline adherence, readmission, clinical cure rate, and adverse complications. We performed random-effect meta-analysis to estimate the overall effect size and assessed heterogeneity using the I2 statistics.

Results

We included 17 observational studies and 82 240 patients, of which 10 studies were comparative and pooled in meta-analysis. Overall guideline adherence rate was 65.2%. Guideline-concordant therapy was associated with a statistically significant reduction in 30-day mortality rate (crude odds ratio [OR], 0.49 [95% confidence interval .34-.70; I2 = 60%]; adjusted OR, 0.49 [.37-.65; I2 = 52%]) and in-hospital mortality rate (crude OR, 0.63 [.43-.92]; I2 = 61%). Due to significant heterogeneity, we could not assess the effect of guideline-concordant therapy on length of stay, ICU admission, readmission, clinical cure rate, and adverse complications.

Conclusions

In hospitalized patients with CAP, guideline-concordant therapy was associated with a significant reduction in mortality rate compared with nonconcordant therapy; however, there was limited evidence to support guideline-concordant therapy for other clinical outcomes. Future studies are needed to assess the clinical efficacy and safety of current guideline recommendations.

Prevalence of Penicillin Resistance Among Streptococcus pneumoniae Isolates in a General Hospital in Southwest Saudi Arabia: A Five-Year Retrospective Study

Background The rise in infections caused by penicillin-resistant strains of Streptococcus pneumoniae has become a global concern. However, the magnitude of this problem in Southwest Saudi Arabia has never been investigated. Therefore, this study aims to determine the prevalence of this bacteria in the region using in vitro data. Materials and methods This study retrospectively studied pneumococcal isolates collected by the Microbiology Laboratory of a general hospital in Al Baha, Saudi Arabia, from January 2013 to December 2017. A minimum inhibitory concentration (MIC) ≥ 8 mg/L was used as a cutoff concentration to detect the resistant isolates. Results A total of 201 S. pneumoniae isolates were identified using the VITEK® 2 system (bioMérieux SA, Marcy-l'Étoile, France). Most of these isolates (61%) were obtained from respiratory specimens, including sputum, tracheal aspirates, and bronchoalveolar lavage. Eye swabs accounted for 15% of the isolates, blood samples contributed 12%, ear swabs accounted for 7%, and cerebrospinal fluid (CSF) 3.4%. The resistance of S. pneumoniae during the five years varied from 61% to 76%, with an overall resistance of 70% (141/201). The resistance rate per year was 71% (43/60) in 2013, 76% (35/46) in 2014, 61% (22/36) in 2015, 68% (20/29) in 2016, and 66% (21/30) in 2017. Conclusion The data confirm the presence of penicillin-resistant S. pneumoniae in Southwest Saudi Arabia. Furthermore, the high resistance suggests a potential concern, emphasizing the need for penicillin control, surveillance, and vaccination to address this growing problem.

Resistance to β-lactams in Streptococcus pneumoniae

Streptococcus pneumoniae is an important causal agent of pneumonia, meningitis, sepsis, bacteremia, and otitis media. Penicillin resistance rates in S. pneumoniae have remained stable in Argentina in the last years. In the late '90s more isolates with MIC of penicillin ≥2μg/ml were observed; however, their frequency has decreased in recent years. The phenotypic expression of penicillin resistance is due to a modification in penicillin-binding proteins associated with a mosaic structure in the coding genes. The expansion of successful resistant clones varies among the different regions and is influenced by the use of antibiotics, vaccines, particularly conjugated ones, as well as population density. Parenteral treatment with high doses of penicillin G continues to be effective for the treatment of pneumonia and bacteremia, oral aminopenicillins for otitis media and sinusitis and third generation cephalosporins for meningitis.

Discovery of novel pneumococcal surface antigen A (PsaA) inhibitors using a fragment-based drug design approach

Streptococcus pneumoniae is a leading cause of life-threatening bacterial infections, especially in young children in developing countries. Pneumococcal infections can be treated with β-lactam antibiotics, but rapid emergence of multidrug-resistant strains of S. pneumoniae over the past two decades has emphasized the need to identify novel drug targets. Pneumococcal surface antigen A (PsaA) is one such target, found on the cell surface of S. pneumoniae. It functions as a high-affinity substrate-binding protein, facilitating acquisition of Mn(2+), which has an important role in protecting S. pneumoniae from reactive oxygen species and, hence, oxidative stress. Consequently, PsaA is essential for bacterial survival and an important virulence factor, which makes it a promising target for antibiotic drug development. To design novel PsaA inhibitors, we used a combination of de novo fragment-based drug discovery and in silico virtual screening methods. We profiled a collection of low molecular weight compounds that were selected based on their structural diversity and ability to bind to apo-PsaA in a virtual docking experiment. The screening resulted in two initial hits that were further optimized by structural variation to improve their potency while maintaining their ligand efficiency and favorable physicochemical properties. The optimized hits were validated using a cell-based assay and molecular dynamics simulations. We found that virtual screening substantially augmented fragment-based drug design approaches, leading to the identification of novel pneumococcal PsaA inhibitors.

Characterization of Mucoid and Non-Mucoid Streptococcus pneumoniae Isolated From Outpatients

Background

Streptococcus pneumoniae causes pneumonia, sepsis, and meningitis. This study aimed to investigate the clinical characteristics of mucoid and non-mucoid isolates of S. pneumoniae, and to explore the relationship between the isolate phenotypes and their antibiotic susceptibility.

Methods

Clinical isolates from 3,453 non-repetitive S. pneumoniae (189 mucoid and 3,264 non-mucoid) infections obtained between January 2008 and December 2012 from outpatients at the Kimitsu-Central Hospital were evaluated.

Results

Compared to the non-mucoid isolates, the mucoid phenotypes were more susceptible to certain antibiotics such as erythromycin, clarithromycin, and tetracycline as opposed to clindamycin, chloramphenicol, and rifampicin. The mucoid phenotype was isolated more frequently from schoolchildren, adults, and elderly adults in a variety of clinical sites, including otorrhea, genitalia, pus, and eye discharge than the non-mucoid phenotype. This suggested that mucoid isolates are more likely to be involved than non-mucoid isolates in various local infections. Systemic infection, which indicates invasiveness, was not associated with the mucoid or non-mucoid phenotype.

Conclusions

The results of this study suggest that mucoid isolates tend to have higher susceptibility than non-mucoid isolates to antibiotics. To the best of our knowledge, mucoid and non-mucoid S. pneumoniae isolates considerably differ in terms of clinical isolation site and age-specific prevalence.

Determination of vancomycin minimum inhibitory concentration for ceftazidime resistant Streptococcus pneumoniae in Iran

BACKGROUND

In the context of growing health concerns over antibiotic resistance, the evaluation of the minimum inhibitory concentration (MIC) of vancomycin for Streptococcus pneumoniae (S. pneumoniae) strains resistant to ceftazidime becomes important for guiding health policy makers. The aim of this study was to determine vancomycin MIC of ceftazidime resistant S. pneumoniae strains.

METHODS

Fifty identified serotypes of ceftazidime resistant S. pneumoniae strains were included in the study. The vancomycin MIC of the above mentioned bacteria was determined based on the 0.5 McFarland standards, by using a microdilution broth and the Etest method.

RESULTS

The results showed that out of 50 ceftazidime resistant strains of S. pneumoniae, 46 strains (92%) have shown a vancomycin MIC ≤0.19 - 0.1.5 μg/ml and only four strains (8%) have shown a vancomycin MIC equal to 1.5 μg/ml and the related maximum zone of inhibition was of 10 millimeter diameters.

CONCLUSIONS

The results of this investigation point out the emergence of S. pneumoniae strains with a vancomycin MIC ≥1.5 μg/ml, which were resistant to ceftazidime. This finding uncovers a major health concern: a vancomycin MIC higher than 1.5 μg/ml and maximum zone of inhibition of only 10 millimeter. These findings represent an important warning for health authorities globally, concerning the treatment of patients, as the occurrence of S. pneumoniae strains with decreased vancomycin susceptibility has been demonstrated.

A qualitative study of pharmacists' perceptions of, and recommendations for improvement of antibiotic use in Qatar

BACKGROUND

Use of antibiotics has been correlated with increasing rates of resistance. Pharmacists are ideally positioned as front line health care providers to limit indiscriminate antibiotic use and promote the safe and effective administration of these medications.

OBJECTIVE

The aim of this project was to assess pharmacists' opinions relating to antibiotic utilization in the community setting.

SETTING

Doha, Qatar.

METHOD

Community and primary care pharmacists were invited to participate in one of three focus groups or a semi-structured interview at Qatar University or at their site of employment. A total of 22 community and primary care pharmacists participated in this study. Interviews were facilitated using a focus group guide, were recorded, and later transcribed. Transcripts were reviewed for recurring themes and coded using Nvivo software for qualitative research.

MAIN OUTCOME MEASURE

Pharmacists' perceptions.

RESULTS

Five major themes emerged from a series of focus groups and interviews. Themes which recurred across interview groups included: misconceptions and inappropriate practices by patients and healthcare providers, currently implemented strategies, perceived barriers, ways to overcome perceived barriers, and targets for improvement of antibiotic use in Qatar. The greatest need, as identified by pharmacists in this study was increased knowledge of the general population about appropriate antibiotic use through various educational interventions.

CONCLUSION

Pharmacists report a number of misconceptions and inappropriate practices relating to antibiotic use in Qatar by patients and healthcare providers. Education to improve knowledge of appropriate antibiotic use is needed. Despite recognition of these issues, barriers are preventing pharmacists from implementing strategies to improve antibiotic use in Qatar.

Pattern of Antibiotic Resistance ofStreptococcus pneumoniaein a Hospital in the Eastern Province of Saudi Arabia

The objective of the study was to evaluate the pattern of antibiotic resistance of Streptococcus pneumoniae at Saudi Aramco Medical Services Organization (SAMSO) in the Eastern Province of Saudi Arabia. We identified, retrospectively, S. pneumoniae isolates from January 1999 to December 2002. Antimicrobial susceptibility and clinical data were collected and analyzed. A total of 162 isolates of S. pneumoniae were identified in the study period. Of these isolates, 94 (58%) isolates were obtained from out-patients and 68 (42%) were obtained from in-patients. Thirty-five percent of isolates were from blood, 46% from the respiratory tract, and the remainder were obtained from other sites. Of these isolates, 83 (51%) were penicillin-susceptible and the remaining 79 (48.8%) were not penicillin susceptible. High-level resistance to penicillin existed in 19.8% of the total isolates. Prevalence of resistance to erythromycin, tetracycline and trimethoprim-sulfamethoxazole was 25%, 29%, and 42% respectively. None of the isolates was resistant to vancomycin or ceftriaxone. However, 12% of the isolates showed multi-drug resistance. Streptococcus pneumoniae shows 19.8% high-level penicillin resistance and 12% multi-drug resistance. These findings call for wiser use of antibiotics.

Efficacy of levofloxacin versus cefuroxime in treating acute exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Antibiotic treatment is one of the major pharmacologic treatments for acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, the choice of antibiotic depends on the local resistance pattern. A multicenter, randomized, controlled trial was done in patients with AECOPD to compare the efficacy of levofloxacin with that of cefuroxime axetil.

METHODS

Patients with AECOPD and without radiographic evidence of pneumonia were enrolled and randomized to either levofloxacin 500 mg daily or cefuroxime 250 mg twice daily in the mildmoderate exacerbation group, or 500 mg twice daily in the severe exacerbation group, for seven days. Clinical efficacy and microbiologic response were evaluated 5-7 days after the last dose.

RESULTS

Treatment was clinically successful in 90.4% of patients in the levofloxacin group, and in 90.6% of patients in the cefuroxime group (95% confidence interval -9.40 to 10.91), within a noninferiority margin of 10%. The microbiologic response appeared to be higher in the levofloxacin group, but the difference was not statistically significant. The safety profile was similar in both groups.

CONCLUSION

Levofloxacin is not inferior to cefuroxime with regard to clinical efficacy in treating AECOPD.

Acute bacterial meningitis in infants and children: epidemiology and management

Acute bacterial meningitis (ABM) continues to be associated with high mortality and morbidity, despite advances in antimicrobial therapy. The causative organism varies with age, immune function, immunization status, and geographic region, and empiric therapy for meningitis is based on these factors. Haemophilus influenzae type b (Hib), Streptococcus pneumoniae, and Neisseria meningitidis cause the majority of cases of ABM. Disease epidemiology is changing rapidly due to immunization practices and changing bacterial resistance patterns. Hib was the leading cause of meningitis in children prior to the introduction of an effective vaccination. In those countries where Hib vaccine is a part of the routine infant immunization schedule, Hib has now been virtually eradicated as a cause of childhood meningitis. Vaccines have also been introduced for pneumococcal and meningococcal diseases, which have significantly changed the disease profile. Where routine pneumococcal immunization has been introduced there has been a reported increase in invasive pneumococcal disease due to non-vaccine serotypes. In those parts of the world that have introduced conjugate meningococcal vaccines, there has been a significant change in the epidemiology of meningococcal meningitis. As a part of the United Nations Millennium Development Goal 4, the WHO has introduced a new vaccine policy to improve vaccine availability in resource poor countries. In addition, antibiotic resistance is an increasing problem, especially with pneumococcal infection. Effective treatment focuses on early recognition and use of effective antibiotics. This review will attempt to focus on the changing epidemiology of ABM in pediatric patients due to vaccination, the changing patterns of infecting bacterial serotypes due to vaccination, and on antibiotic resistance and its impact on current management strategies.

Severe pneumococcal community-acquired pneumonia admitted to medical Tunisian ICU

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). There are no available data about this disease in Tunisian intensive care patients. The objective of this study is to describe the clinical and microbiological features of pneumococcal CAP and determine the prognostic factors. This is a retrospective cohort study of all pneumococcal CAP cases hospitalized in the medical intensive care unit (ICU) of Hospital A. Mami of Ariana (Tunisia) between January 1999 and August 2008. Included were 132 patients (mean age, 49.5 years; 82.6% males); 30 patients had received antimicrobial treatment before hospital admission. The mean of the Simplified Acute Physiology Score II was 32.9. All patients had an acute respiratory failure; 34 patients (25.8%) had pneumococcal bacteremic CAP. Among the isolated strains, 125 antimicrobial susceptibility tests were performed. The use of the new Clinical and Laboratory Standards Institute breakpoints for susceptibility when testing penicillin against S. pneumoniae showed that all isolated strains were susceptible to penicillin. The mortality rate was 25%. The need of mechanical ventilation at admission [odds ratio (OR), 3.4; 95% confidence interval (CI), 1.67-6.94; P = 0.001), Sepsis-related Organ Failure Assessment (SOFA) score at admission ≥4 (OR, 3.1; 95% CI, 1.56-6.13; P = 0.001), and serum creatinine at admission ≥102 μmol/l (OR, 1.8; 95% CI, 1.02-3.17; P = 0.043) were independent factors related to ICU mortality. In conclusion, pneumococcal CAP requiring hospitalization in the ICU is associated with high mortality. All isolated stains were susceptible to penicillin.

Microbiology of the middle ear fluid in Costa Rican children between 2002 and 2007

BACKGROUND

Because the microbiology and susceptibility patterns of middle ear fluid pathogens in children with otitis media change over time, an active surveillance is recommended to establish appropriate therapeutic guidelines.

OBJECTIVE

To analyze the microbiology and susceptibility pattern of middle ear pathogens obtained from Costa Rican children with acute otitis media (AOM), recurrent otitis media (ROM) and therapeutic failure otitis media (OMTF) between 2002 and 2007.

PATIENTS AND METHODS

1108 children aged 2-92 months who participated in various otitis media clinical trials between the years 2002 and 2007.

RESULTS

Among the study population, 880 were children with AOM (61% <24 months of age), 138 were children with ROM (54% <24 months of age) and 90 were children with OMTF (67% <24 months of age). Bilateral otitis media was more frequent in children with OMTF (44%) than in children with AOM (37%) (P=0.19) and ROM (27%) (P=0.009). Presence of siblings <8 years of age was more frequently observed in children with OMTF (73%) than in children with ROM (65%) (P=0.0001) and AOM (47%) (P=0.000002). Overall Streptococcus pneumoniae (44%) was the most common pathogen isolated followed by Haemophilus influenzae (37%), Moraxella catarrhalis (11%) and Streptococcus pyogenes (4%). S. pneumoniae was the most common pathogen in AOM (44%) and ROM (47%), however, H. influenzae was the most common pathogen in OMTF (40%). Among all H. influenzae, an increase in the number of β-lactamase producing strains was observed from 5.2% in 2001 to 14% (P=0.04) in 2007 and this was associated with an increase in the use of amoxicillin. An increase in the number of M. catarrhalis was also observed, from 3% (9/350) in 2001 to 11% (71/628) (P=0.000003) in 2007. During the study period the incidence of penicillin non-susceptible S. pneumoniae was 42/211 (20%) in children with AOM; 5/35 (17%) in children with ROM and 5/17 (42%) in children with OMTF. M. catarrhalis cases increased from 8% in 2004 to 17% in 2007 (P=0.0005) and S. pyogenes decreased from 7% in 2002-2004 to 1% in 2005-2007 (P=0.001).

CONCLUSIONS

In Costa Rica, S. pneumoniae remains the most common pathogen in children with AOM and ROM whereas non-typable H. influenzae remains the most common pathogen in children with OMTF. A significant increase in the number of β-lactamase positive H. influenzae and M. catarrhalis has been observed in recent years.

Microbiology of otitis media: a moving target

The microbiology of acute otitis media (AOM) is linked to the nasopharyngeal commensal flora. This respiratory ecosystem undergoes various selective pressures, such as antibiotic consumption and vaccine use. Socio-economic conditions also influence the bacterial composition of the nasopharynx. Streptococcus pneumoniae, non-encapsulated Haemophilus influenzae, Moraxella catarrhalis, and group A Streptococcus are the leading causes of bacterial AOM worldwide. This paper will discuss the causes and consequences of recent shifts in the underlying microbiology of AOM.

Acute bacterial meningitis caused by Streptococcus pneumoniae resistant to the antimicrobian agents and their serotypes

The main objectives of this study are to evaluate the resistance rates of Streptococcus pneumonia to penicillin G, ceftriaxone and vancomycin in patients with meningitis; to analyze possible risk factors to the antimicrobian resistance; to describe the serotypes detected and to suggest an initial empirical treatment for meningitis. The sensitiveness and serotypes of all isolated S. pneumoniae of patients with acute bacterial meningitis received by the Paraná State Central Laboratory from April 2001 to august 2002 have been evaluated. One hundred S. pneumoniae have been isolated, of which 15% were resistant to penicillin, 1% to cephalosporin and 0% to vancomycin. The serotypes most found were 14 (19%), 3 and 23F (10% each). When only the resistant serotypes were analyzed, the most prevalent was the 14 with 44%. The risk factors found in relation to the S. pneumoniae resistance were: age under one year old (p=0.01) and previous use of antibiotic (p=0.046). The resistance rates found, which were moderate to penicillin, low to cephalosporin and neutral to vancomycin, suggest the isolated use of a 3rd generation cephalosporin as an initial empirical therapy for the treatment of acute bacterial meningitis with a communitarian background.

Drug-resistant pneumococci in children with acute lower respiratory infections in Vietnam

BACKGROUND

Acute lower respiratory infections (ALRI), primarily pneumonia, are the leading cause of death in children under 5 years of age. Most of these deaths occur in Africa and southeast Asia. Increasing rates of drug resistance in pneumococcal strains emphasize the necessity of prevention of pneumococcal vaccines. The aim of the present study was to determine the frequency of drug resistance and the distribution of serotype of pneumococcal strains isolated from pediatric patients with ALRI in Vietnam.

METHODS

Two hundred and twenty pediatric patients with ALRI under 5 years of age were enrolled in Hanoi, Vietnam between 2001 and 2002. Bacterial pathogens with a heavy growth (10(6) c.f.u./mL) were isolated from nasopharyngeal secretions on quantitative culture. Fifty-three pneumococcal strains isolated from the nasopharynx of pediatric patients were examined for antibiotic susceptibility including drug-resistant genes and serotyping.

RESULTS

A total of 73.6% of pneumococcal strains were genotypic penicillin-resistant Streptococcus pnemoniae (gPRSP), possessing altered penicillin-binding protein genes pbp 1a + 2x + 2b; 67.9% of these strains were gPRSP and simultaneously had the ermB gene, which is responsible for high resistance to erythromycin. The majority of gPRSP strains were serotype 19F or 23F.

CONCLUSION

gPRSP strains with serotype 19F or 23F are highly prevalent among pediatric patients with ALRI under 5 years of age in Hanoi, Vietnam.

Rapid identification of penicillin and macrolide resistance genes and simultaneous quantification of Streptococcus pneumoniae in purulent sputum samples by use of a novel real-time multiplex PCR assay

We evaluated a real-time quantitative PCR combined with a multiplex PCR assay for the quantification of Streptococcus pneumoniae and the simultaneous detection of drug-resistant genes by gel-based PCR, using purulent sputum samples. This assay correctly quantified S. pneumoniae and identified their penicillin and erythromycin susceptibilities directly from samples within 3 h.

Comparative immune responses of patients with chronic pulmonary diseases during the 2-year period after pneumococcal vaccination

Antibody responses to a 23-valent pneumococcal vaccine for Streptococcus pneumoniae serotypes 6B, 14, 19F, and 23F in 84 patients with chronic pulmonary diseases over a 2-year period after vaccination were examined by using a third-generation enzyme-linked immunosorbent assay. Of these patients, 28 (31%) were low responders who had developed increases of at least twofold in the levels of serotype-specific immunoglobulin G (IgG) in sera for none of the four serotypes at 1 month after vaccination. Although no specific clinical features of low responders were evident, their prevaccination levels of IgG for all serotypes were higher than those of responders. In responders, the levels of IgG specific for serotypes 14 and 23F in sera were greatly increased 1 month after vaccination and those specific for serotypes 6B and 19F were moderately increased. In contrast, no significant increases in the levels of IgG specific for serotypes 6B, 19F, and 23F in the low responders during the same period were found, but the levels of IgG specific for serotype 14 did increase. Although a rapid decline in the levels of IgG for all serotypes in responders between 1 month and 6 months after vaccination was found, the levels of IgG specific for serotypes 14 and 23F in sera remained higher than the prevaccination levels for at least 2 years after vaccination. These data suggest the need for the revaccination of responders but not low responders among patients with chronic pulmonary diseases. Revaccination as early as 3 years postvaccination is recommended for responders to increase the reduced levels of IgG in sera, especially those specific for the weak vaccine antigens.

Impact of initial discordant treatment with beta-lactam antibiotics on clinical outcomes in adults with pneumococcal pneumonia: a systematic review

OBJECTIVE

To systematically examine the available evidence regarding the effect of initial discordant therapy with beta-lactam antibiotics on mortality, clinical success, and bacteriological eradication in patients with pneumococcal pneumonia.

METHODS

We analyzed prospective studies that compared the clinical effectiveness of concordant (active in vitro) beta-lactam monotherapy with discordant (inactive in vitro) monotherapy with the same beta-lactam in patients with pneumococcal pneumonia. Relevant studies were identified from searches of the PubMed database (1950 to November 2005) and references from articles. Outcomes between groups of patients who received concordant and discordant treatment were compared by simple pooling of data and by estimation of pooled odds ratios or risk difference (RD), when applicable.

RESULTS

Six prospective studies were included in our analysis. No statistically significant difference was found in mortality of patients treated with beta-Iactam concordant and discordant therapy (51/275 [19%] vs 9/42 [21%]; P = .66; data from 6 studies; RD, -0.05; 95% confidence interval [CI], -0.23 to 0.12; data from 5 studies). In addition, no statistically significant difference was found regarding clinical success (37/42 [88%] vs 5/6 [83%]; P = .57; odds ratio, 2.57; 95% CI, 0.46 to 14.34; RD, 0.07; 95% CI, -0.36 to 0.50; data from 3 studies) or bacteriological success (24/30 [80%] vs 3/3 [100%]; P = .99; and RD, -0.18; 95% CI, -0.79 to 0.42; data from 2 studies) between concordant and discordant therapy.

CONCLUSION

The initial discordant treatment with beta-lactam antibiotics was not associated with a statistically significant Increase in mortality or clinical or bacteriological failure of therapy for pneumococcal pneumonia.

Antimicrobial resistance of nasopharyngeal pneumococci from children from day-care centres and orphanages in Russia: results of a unique prospective multicentre study

This study assessed the antimicrobial resistance of nasopharyngeal pneumococci isolated from children aged < 5 years in day-care centres and orphanages throughout Russia during 2001-2002. Swabs were collected from 2484 children in 43 day-care centres and eight orphanages in 11 cities of European Russia, and from 1669 children in 37 day-care centres and three orphanages in eight cities of Asian Russia, with a total of 1144 and 912 Streptococcus pneumoniae isolates being recovered in European and Asian Russia, respectively. All macrolide-non-susceptible (MICs 0.5-128 mg/L) and fluoroquinolone-non-susceptible (ciprofloxacin MICs > or = 4 mg/L) isolates were tested for resistance mechanisms and clonal relatedness. Non-susceptibility rates, by CLSI criteria, were 19.3%, 0.9% and 0.4% for penicillin G, cefotaxime and amoxycillin-clavulanate, respectively. Resistance to macrolides and lincosamides was also relatively low, i.e., < 7% for clindamycin and 14- and 15-membered macrolides. The highest rates of non-susceptibility were for tetracycline and co-trimoxazole (52.0% and 64.5%, respectively). No clones resistant to ciprofloxacin (MICs > or = 8 mg/L) were found, but 1.7% of isolates were non-susceptible (MIC 4 mg/L). No resistance was found to levofloxacin, gemifloxacin, telithromycin or vancomycin. Pulsed-field gel electrophoresis analysis showed no relationship between ciprofloxacin- and macrolide-non-susceptible isolates in European and Asian Russia. Resistance among macrolide-resistant isolates resulted mostly from the presence of erm(B) and mef(A), and from changes in L4; additionally, L22 mutations were common in isolates from Asian Russia. Non-susceptibility to quinolones was associated with mutations in parC and parE among European isolates. Asian Russian isolates had mutations in parC and gyrA, and alterations in parE were more common. There were substantial differences in non-susceptibility and mechanisms of resistance between pneumococci from Asian and European Russia, with orphanages appearing to be 'hot-spots' of resistance.

Gram-positive cocci infections in intensive care: guide to antibacterial selection

The incidence of multiresistance in Gram-positive cocci causing infections in critically ill patients admitted to the intensive care unit (ICU) has increased notably in recent years. Thus, therapeutic proposals have been modified according to the emergence of multiresistant cocci and adapted to epidemiological markers of individual infectious processes, geographical variations of these markers, the availability of new antibacterials, and advances in the knowledge of pharmacokinetic and pharmacodynamic aspects of their use. The current management of critically ill patients should consider new therapeutic approaches, such as the "de-escalating strategy", which includes the administration of empirical antibacterials active against multiresistant pathogens followed by directed treatment based on unequivocal data from antibacterial-susceptibility testing. Optimisation of antibacterial treatment should be viewed in the context of the need to determine plasma drug concentrations, pharmacoeconomic considerations and control of drug-related adverse events. Therapeutic proposals should be developed within the framework of the antibacterial policy of each hospital. The present review is focused on the description of the therapeutic strategies for the main infectious processes caused by Gram-positive cocci in severely ill patients admitted to the ICU according to a review of the pertinent literature and the clinical experience of the authors.

Drug-resistant genes and serotypes of pneumococcal strains of community-acquired pneumonia among adults in Japan

BACKGROUND

A high frequency of drug-resistant pneumococci has been reported in Asian countries. Few data on the drug-resistance or serotype of pneumococcal strains responsible for community-acquired pneumonia (CAP), however, are available for the past two decades in Japan.

METHODOLOGY

Susceptibility to antibiotics and the genotype of antibiotic-resistant genes and serotypes of Streptococcus pneumoniae isolates from 114 adult patients with CAP were examined in a nationwide study in Japan between 2001 and 2003.

RESULTS

Most of the cases were non-bacteraemic pneumonia and the case fatality rate was 4.4%. The most frequent genotype of the pbp gene was pbp1a + 2x + 2b (gPRSP; 36.8%) followed by pbp 2x (28.1%) and of the macrolide-resistant gene, it was ermB (50.0%). The most common serotype was 19F (29.1%), followed by serotype 23F (13.2%), 6B (12.3%) and 3 (11.4%). The coverage of serotypes of isolates by a 23-valent pneumococcal polysaccharide vaccine (PPV) would be 82.5% in these patients with CAP. Most of strains with serotypes 19F and 23F were gPRSP. A cluster of serotype 3 strains associated with the pbp 2x and ermB gene was also noted.

CONCLUSION

A high frequency of altered pbp gene mutations or of macrolide-related genes and a high serotype coverage by the 23-valent PPV found in our study of pneumococcal pneumonia facilitates attempts to increase the coverage rate of the 23-valent PPV in adults older than 65 years in Japan.

Epidemiological relationships among penicillin non-susceptible Streptococcus pneumoniae strains recovered in the Czech Republic

Since 1986, penicillin non-susceptible pneumococci (PNSP) have been found in the Czech Republic. As documented by a nationwide study, the proportion of invasive strains with reduced susceptibility to penicillin has fluctuated around 5 % in the past decade. Although the level of resistance to penicillin remains stable, the contribution of different capsular serotypes among the PNSP population varies. Whereas serotype 19A was predominantly associated with penicillin resistance until 1997, serotype 9V became most common among PNSP strains in 1998. In a collection of PNSP strains (n=225) isolated from 2000 to 2002, the most frequent serotype was 9V (n=91, 40.4 %), followed by 19F (n=30, 13.3 %) and 14 (n=25, 11.5 %). PFGE and multilocus sequence typing were used to characterize a set of PNSP of the currently predominant serotypes 9V (n=42), 14 (n=15) and 19F (n=14). The Spain(9V)-3 clone [sequence type (ST) 156] was responsible for a large proportion (100 % of serotype 9V strains, n=42; 93.3 % of serotype 14 strains, n=14) of the analysed strains. A representative of the Taiwan(19F)-14 clone (ST 236) was also recovered in the Czech Republic (a single isolate of serotype 19F). These findings confirm the spread of the major penicillin-resistant clones in the Czech Republic.

Mechanisms by which antibiotics promote dissemination of resistant pneumococci in human populations

Mechanisms by which antimicrobials contribute to dissemination of pneumococcal resistance are incompletely characterized. A serial cross-sectional study of nasopharyngeal pneumococcal carriage in healthy, home-living children <or=6 years of age was conducted in four rural communities-two in Utah (1998-2003) and two in Idaho (2002-2003). Prevalence odds ratios for carriage of resistant pneumococci (OR(res)) and of susceptible pneumococci (OR(sus)) were estimated. Dynamic transmission models were developed to facilitate a mechanistic interpretation of OR(res) and OR(sus) and to compare the population impact of distinct antimicrobial classes. A total of 5,667 cultures were obtained; 25% of the cultures were positive, and 29% of isolates exhibited reduced susceptibility to penicillin. The adjusted OR(res) for recent individual and sibling cephalosporin use was 2.2 (95% confidence interval: 1.4, 3.4) and 1.8 (95% confidence interval: 1.0, 3.3), respectively. Neither individual nor sibling penicillin use was associated with increased OR(res). Rather, recent use of penicillins was associated with decreased carriage of susceptible pneumococci (OR(sus) = 0.2, 95% confidence interval: 0.1, 0.3). In simulations, both types of effects promoted dissemination of resistant pneumococci at the population level. Findings show that oral cephalosporins enhance the risk of acquiring resistant pneumococci. Penicillins accelerate clearance of susceptible strains. The effect of penicillins in increasing resistance is shared equally by treated and untreated members of the population.

The -omics era and its impact

OBJECTIVE

To review the advances in clinically useful molecular biologic techniques and to identify their applications, as presented at the 12th Annual William Beaumont Hospital DNA Symposium.

DATA SOURCES

The 7 manuscripts submitted were reviewed and their major findings were compared with literature on the same or related topics.

STUDY SELECTION

Manuscripts address the use of molecular techniques in the detection of severe acute respiratory syndrome (SARS) and bacterial ribosome mutations, which may lead to ribosome-targeted drug resistance; pharmacogenomics as a clinical laboratory service and example of warfarin dosing using CYP2C9 mutation analysis; definition of the potential of cytosine arabinoside incorporation into DNA to disrupt transcription using an in vitro model of oligonucleotides; use of laser capture microdissection to isolate solid tumor cells free of nontumor cells; and molecular methods used to classify lymphomas.

DATA SYNTHESIS

Two current issues related to the use of molecular tests in the clinical laboratories are (1) decentralization of molecular-based testing to a variety of nonmolecular laboratories and (2) need for wider acceptance of molecular-based testing through its incorporation in clinical practice guidelines. Molecular methods have had a major impact on infectious disease through the rapid identification of new infectious agents, SARS, and the characterization of drug resistance. Pharmacogenomics identifies the genetic basis for heritable and interindividual variation in response to drugs. The incorporation of the nucleoside analog, cytosine arabinoside, into DNA leads to local perturbation of DNA structure and reduces the ability of transcription factors to bind to their specific DNA binding elements as measured by electrophoretic mobility shift assays. Laser capture microdissection of tumor cells can provide an adequate number of cells for whole genome amplification. Gene expression microassay profiles of various lymphomas have modified classification systems and predict prognosis and response to therapy.

CONCLUSIONS

The current -omics era will continue to emphasize the use of microarrays and database software for genomic, transcriptomic, and proteomic screening to search for a useful clinical assay. The number of molecular pathologic techniques will expand as additional disease-associated mutations are defined.

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

The Alexander Project is a global surveillance study conducted from 1992 to 2001. Minimum inhibitory concentrations and percent resistance to a panel of antimicrobial agents were determined according to National Committee for Clinical Laboratory Standards methodology. Resistance to penicillin (PEN-R) and erythromycin (ERY-R) have increased in the period 1992-2001 by 3.9 and 4.5 times to 20.7% and 27.9%, respectively. Joint PEN-ERY-R has increased 4.9 times, up to 15.3%. In 1992, 57.1% of all PEN-R isolates were also ERY-R, whereas in 2001, 75.8% were ERY-R. Resistance to only 1 antibiotic increased slightly, from 8% in 1992 to 12% in 2001, whereas resistance to more than 1 antibiotic increased 4.3 times, from 6.4% in 1992 to 27.8% of all strains in 2001. Multidrug-resistant pneumococci are an increasingly common finding in the United States. Three of four PEN-R isolates are also multiresistant. The rate of growth of multidrug resistance is higher than that of single antibiotic resistance.

Novel Antibiotic-Resistant Pneumococcal Strains Recovered from the Upper Respiratory Tracts of HIV-Infected Adults and Their Children in Kisumu, Kenya

In a survey of genetic diversity within penicillin-nonsusceptible pneumococcal isolates in Kenya, we examined 162 upper respiratory isolates from 104 human immunodeficiency virus (HIV)-infected adults and 46 children in a cotrimoxazole prophylaxis study. Antibiotic resistance levels were high; 152 (94.4%) were cotrimoxazole nonsusceptible (134 fully resistant) and 124 (77%) were intermediately penicillin resistant. Isolates nonsusceptible to penicillin and cotrimoxazole (PNCNP) were found among 24 of the 29 serotypes encountered, 15 of which have rarely or never had documented nonsusceptibility to penicillin. These included serotypes 3, 4, 7C, 7F, 10A, 11A, 13, 15A, 15B, 16F, 17F, 19B, 21, 35A, and 35B. Segments of pbp2b genes from 9 PNCNP (serotypes 3, 13, 15A, 16F, 20, and 35A) were typical of resistance-conferring alleles in that they were highly divergent and contained two substitutions thought to be critical for resistance. Similarly, the dhfr genes from 3 PNCNP were divergent and contained a substitution required for cotrimoxazole resistance. Multilocus sequence typing (MLST) of 48 PNCNP revealed 33 sequence types (STs), none of which were previously recorded at http://www.mlst.net. Comparisons with all known STs revealed that 23 of these STs were unrelated to other known STs, whereas 10 STs were highly related to STs from internationally disseminated strains, including 2 of the 26 antibiotic-resistant clones recognized by the Pneumococcal Molecular Epidemiology Network. Based upon differing serotypes expressed by strains of identical or closely similar genotypes, there has been an extensive history of capsular switching within seven genetic clusters represented by these 10 STs and related STs described at http://www.mlst.net.

PROTEKT 1999–2000: a multicentre study of the antimicrobial susceptibility of respiratory tract pathogens in Japan

DESIGN

A six-centre study in Japan during the winter of 1999-2000 assessed the in vitro activity of >20 antimicrobial agents against the common respiratory pathogens Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, and Moraxella catarrhalis. The minimum inhibitory concentrations (MIC) of each antimicrobial was determined against these isolates using National Committee for Clinical Laboratory Standards (NCCLS) methodology.

RESULTS

Among S. pneumoniae isolates, 44.5% were penicillin resistant. The macrolide resistance rate was 77.9% with 90.5% of penicillin-resistant strains also being macrolide resistant. Resistance mechanisms in macrolide-resistant isolates were identified as mef(A) or erm(B) in 42.5% and 52.5%, respectively. Of the fluoroquinolone-resistant isolates (1.3%), most were also penicillin and macrolide resistant. All strains were inhibited by telithromycin at <or=1mg/L. Among S. pyogenes isolates, erythromycin resistance was 17.5% overall but showed considerable variation among the six centres. For H. influenzae, 8.5% produced beta-lactamase and a single beta-lactamase-negative, ampicillin-resistant isolate (0.36%) was obtained, and there was no fluoroquinolone resistance. All isolates were susceptible to telithromycin. Most antimicrobials showed good activity against M. catarrhalis, although 96.7% were beta-lactamase positive.

CONCLUSION

The prevalence of antimicrobial resistance to macrolides, penicillin and the fluoroquinolones among the common respiratory pathogens is high in Japan.

Surveillance of antimicrobial resistance at a tertiary hospital in Tanzania

BACKGROUND

Antimicrobial resistance is particularly harmful to infectious disease management in low-income countries since expensive second-line drugs are not readily available. The objective of this study was to implement and evaluate a computerized system for surveillance of antimicrobial resistance at a tertiary hospital in Tanzania.

METHODS

A computerized surveillance system for antimicrobial susceptibility (WHONET) was implemented at the national referral hospital in Tanzania in 1998. The antimicrobial susceptibilities of all clinical bacterial isolates received during an 18 months' period were recorded and analyzed.

RESULTS

The surveillance system was successfully implemented at the hospital. This activity increased the focus on antimicrobial resistance issues and on laboratory quality assurance issues. The study identified specific nosocomial problems in the hospital and led to the initiation of other prospective studies on prevalence and antimicrobial susceptibility of bacterial infections. Furthermore, the study provided useful data on antimicrobial patterns in bacterial isolates from the hospital. Gram-negative bacteria displayed high rates of resistance to common inexpensive antibiotics such as ampicillin, tetracycline and trimethoprim-sulfamethoxazole, leaving fluoroquinolones as the only reliable oral drugs against common Gram-negative bacilli. Gentamicin and third generation cephalosporins remain useful for parenteral therapy.

CONCLUSION

The surveillance system is a low-cost tool to generate valuable information on antimicrobial resistance, which can be used to prepare locally applicable recommendations on antimicrobial use. The system pinpoints relevant nosocomial problems and can be used to efficiently plan further research. The surveillance system also functions as a quality assurance tool, bringing attention to methodological issues in identification and susceptibility testing.

Solution structure and function of an essential CMP kinase of Streptococcus pneumoniae

Streptococcus pneumoniae is a major human pathogen that causes high mortality and morbidity and has developed resistance to many antibiotics. We show that the gene product from SP1603, identified from S. pneumoniae TIGR4, is a CMP kinase that is essential for bacterial growth. It represents an attractive drug target for the development of a novel antibiotic to overcome the problems of drug resistance development for this organism. Here we describe the three-dimensional solution structure of the S. pneumoniae CMP kinase as determined by NMR spectroscopy. The structure consists of eight alpha-helices and two beta-sheets that fold into the classical core domain, the substrate-binding domain, and the LID domain. The three domains of the protein pack together to form a central cavity for substrate-binding and enzymatic catalysis. The S. pneumoniae CMP kinase resembles the fold of the Escherichia coli homolog. An insertion of one residue is observed at the beta-turn in the substrate-binding domain of the S. pneumoniae CMP kinase when compared with the E. coli homolog. Chemical shift perturbations caused by the binding of CMP, CDP, and ATP revealed that CMP or CDP binds to the junction between the core and substrate-binding domains, whereas ATP binds to the junction between the core and LID domains. From NMR relaxation studies, we determined that the loops in the LID domain are highly mobile. These mobile loops could aid in the closing/opening of the LID domain during enzyme catalysis.

Antimicrobial prescribing patterns for respiratory diseases including tuberculosis in Russia: a possible role in drug resistance?

BACKGROUND

Inappropriate antibiotic prescribing exposes patients to the risk of side effects and encourages the development of drug resistance across antimicrobial groups used for respiratory infections including tuberculosis (TB).

AIM

Determine among Russian general practitioners and specialists: (1) sources of antimicrobial prescribing information; (2) patterns of antimicrobial prescribing for common respiratory diseases and differences between primary and specialist physicians; (3) whether drug resistance in TB might be linked to over-prescribing of anti-TB drugs for respiratory conditions.

METHODS

Point-prevalence cross-sectional survey involving all 28 primary care, general medicine and TB treatment institutions in Samara City, Russian Federation. In this two-stage study, a questionnaire was used to examine doctors' antimicrobial (including TB drugs) prescribing habits, sources of prescribing information, management of respiratory infections and a case scenario ('common cold'). This was followed by a case note review of actual prescribing for consecutive patients with respiratory diseases at three institutions.

RESULTS

Initial questionnaires were completed by 81.3% (425/523) of physicians with 78.4% working in primary care. Most doctors used standard textbooks to guide their antimicrobial practice but 80% made extensive use of pharmaceutical company information. A minority of 1.7% would have inappropriately prescribed antibiotics for the case and 0.8-1.8% of respondents would have definitely prescribed TB drugs for non-TB conditions. Of the 495 respiratory cases, 25% of doctors prescribed an antibiotic for a simple upper respiratory tract infection and of 8 patients with a clinical diagnosis of TB, 4 received rifampicin monotherapy alone. Ciprofloxacin was widely but inappropriately used.

CONCLUSION

Doctors rely on information provided by pharmaceutical companies; there was inappropriate antibiotic prescribing.

Limited spread of penicillin-nonsusceptible pneumococci, Skåne County, Sweden

In response to increasing frequencies of penicillin-nonsusceptible pneumococci (PNSP), for which the MIC of penicillin was >0.12 mg/L, in Skåne County, southern Sweden, national recommendations were initiated in 1995 to limit the spread of pneumococci with high MICs (> or =0.5 mg/L) of penicillin (PRP), especially among children of preschool age. Traditional communicable disease control measures were combined with actions against inappropriate antimicrobial drug use. During the first 6 years that these recommendations were applied in Skåne County, the average frequency of penicillin-resistant pneumococci has been stable at =2.6%, as has the average PNSP frequency (7.4%). However, PNSP have been unevenly distributed in the county, with the highest frequencies in the southwest. Simultaneously, the rate of antimicrobial drug use for children <6 years of age was reduced by 20%. Thus the spread of PNSP between and within the municipalities in the county has been limited.

Clinical Outcomes of Pneumococcal Pneumonia Caused by Antibiotic-Resistant Strains in Asian Countries: A Study by the Asian Network for Surveillance of Resistant Pathogens

To evaluate the clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries, we performed a prospective observational study of 233 cases of adult pneumococcal pneumonia in 9 Asian countries from January 2000 to June 2001. Among 233 isolates, 128 (55%) were not susceptible to penicillin (25.3% were intermediately susceptible, and 29.6% were resistant). Clinical severity of pneumococcal pneumonia was not significantly different between antibiotic-resistant and antibiotic-susceptible groups. Mortality rates among patients with pneumococcal pneumonia caused by penicillin-, cephalosporin-, or macrolide-resistant strains were not higher than those with antibiotic-susceptible pneumococcal pneumonia. Bacteremia and mechanical ventilation were significant risk factors for death, but any kind of antibiotic resistance was not associated with increased mortality due to pneumococcal pneumonia. Outcome of pneumococcal pneumonia was not significantly affected by drug resistance, and current antimicrobial regimens are mostly effective in the treatment of pneumococcal pneumonia, despite the widespread emergence of in vitro resistance.

Prospective observational study of bacteremic pneumococcal pneumonia: Effect of discordant therapy on mortality*

STUDY OBJECTIVE

To evaluate the effect of discordant empirical therapy on outcome in bacteremic pneumococcal community-acquired pneumonia.

DESIGN

Prospective observational study.

SETTING

A 600-bed teaching hospital with a reference area of 400,000 inhabitants.

PATIENTS

All patients aged > or =18 yrs with a diagnosis of community-acquired pneumonia whose blood cultures, obtained within the first 48 hrs of hospitalization, demonstrated growth of Streptococcus pneumoniae were included in the study.

METHODS

Discordant therapy was defined as failure to administer an antibiotic with in vitro activity against the isolated strain within 24 hrs of hospital admission. The 2002 breakpoints recommended for respiratory infections by the National Committee for Clinical Laboratory Standards were used to classify therapy.

RESULTS

A total of 100 patients with bacteremic pneumococcal pneumonia were identified. Penicillin- and macrolide-resistant strains were identified in 29 and 18 cases, respectively. Only two strains had minimum inhibitory concentrations of >2 microg/mL for cephalosporins. Discordant therapy was documented in ten patients, five of whom died. Mortality in patients receiving concordant therapy was 14% (13 of 90). Nursing home residence (odds ratio [OR] = 14.8) and immunocompromise (OR = 11.5) were independently (p <.05) associated with discordant therapy. Risk of discordant therapy was significantly higher (p <.05) when empirical therapy did not include cefotaxime or ceftriaxone (OR = 10.4). Discordant therapy (OR = 27.3), multilobar involvement (OR = 14.2), underlying chronic obstructive pulmonary disease (OR = 9.1), and hospitalization during the previous 12 wks (OR = 7.9) were independently associated (p <.05) with death. The excess mortality for initial discordant therapy was estimated to be 35.6% (95% confidence interval, 3.73-67.4).

CONCLUSIONS

Survival in patients with bacteremic community-acquired pneumococcal pneumonia can be improved by avoiding suboptimal therapy. Using the 2002 breakpoints, it is very unlikely that discordant therapy would be given with ceftriaxone or cefotaxime. Clinical outcome is worse in those patients receiving antimicrobial therapy that in vitro testing suggests would be ineffective.

Pneumococcal bacteremia in a single center in Argentina

OBJECTIVE

To determine the clinical and microbiologic characteristics of pneumococcal bacteremia at Sanatorio Mitre, Buenos Aires, Argentina.

METHODS

One-hundred-and-seven episodes of pneumococcal bacteremia were prospectively analyzed from 1993 to 1998. Demographics, clinical and microbiological variables were studied.

RESULTS

Eighty-one patients (76%) were adults and 26 children (24%). Most cases (98%) were acquired in the community. Seventy-nine patients (74%) had at least one underlying condition. The primary source of bacteremia was found in 91 patients (85%), the lungs being the most common source. Streptococcus pneumoniae was isolated from one sterile site other than the primary focus in 25 patients (23%). Eighty-five (79%) of the Streptococcus pneumoniae were susceptible to penicillin and 22 (21%) showed intermediate or high resistance to penicillin and 2% were additionally resistant to ceftriaxone. Initial antimicrobial therapy was appropriate in 95% of the cases. The overall mortality was 21%, however adults admitted to the intensive care unit (ICU) had higher mortality (81%). No patients under 14 years old died. Multivariate analysis showed that age and recovery of the organisms from a sterile site other than the primary focus were statistically significant predictors of mortality.

CONCLUSION

Bacteremic pneumococcal infections continue to be an important worldwide problem causing morbidity and high mortality despite supportive care and appropriate antimicrobial therapy.

Clonal Analysis ofStreptococcus pneumoniaeNonsusceptible to Penicillin at Day-Care Centers with Index Cases, in a Region with Low Incidence of Resistance: Emergence of an Invasive Type 35B Clone among Carriers

The nasopharyngeal carriage rate of potential respiratory pathogens was studied in 36 index children with a pneumococci nonsusceptible to penicillin (PNSP), in 595 healthy children, and in 123 personnel at 16 day-care centers (DCCs) with index cases in the Stockholm area, an urban area with a low incidence of antibiotic resistant pneumococci, during the winter of 1997-1998. The spread and clonality of PNSP, Haemophilus influenzae and Moraxella catarrhalis, were studied by analyzing antibiotic susceptibility and serotype, and for PSNP also by using pulsed-field electrophoresis (PFGE) and multilocus sequence typing (MLST). In contrast to the low carriage rate found among the adult contacts (2%), 40% of the children harbored pneumococci, of which 20% were PNSP. Nasopharyngeal colonization decreased with age. The 49 PNSP isolates consisted of 20 clones, of which 10 could be identified in more than one child attending the same or different DCCs. In five DCCs, we observed a spread of PNSP from the index case. A novel PNSP clone of type 35B, found to cause invasive disease in several states in the United States, was found to emerge among several carriers at two DCCs . A high proportion of PNSP isolates were multiresistant to antibiotics (34%), which has implications for treatment regimens, even in a country like Sweden where the proportion of PNSP currently is low (3-4%). One PNSP clone of type 9V found among the carriers, has been shown to cause invasive disease in Sweden as well as in other countries, suggesting that one reason for the occurrence of invasive PNSP clones may be their ability to colonize and spread among healthy carriers. Other internationally spread antibiotic resistant pneumococcal clones found were of types 9V, 19F, and 23F.

[A comparison of moxifloxacin and amoxicillin in the treatment of community-acquired pneumonia in Latin America: results of a multicenter clinical trial]

Since community-acquired pneumonia (CAP) is a common disease with a high morbidity rate, it is important to obtain information concerning its etiology and susceptibility to antibiotics across different geographic areas. This study presents data obtained in 5 Latin American counties in the course of an international clinical trial that evaluated the efficacy and safety of treatment with either moxifloxacin or amoxicillin administered for 10 days to patients suspected of having CAP caused by a pneumococcal infection. Details are given of the pathogens identified, the patterns of sensitivity to antibiotics observed, and the clinical and microbiological results obtained.A total of 84 patients were studied, of whom 70 (83.3%) were evaluated at the end of the trial to determine the efficacy and safety of the treatment received. Gram-positive bacteria were found in samples from 29 patients (80.5%). The pathogen was Streptococcus pneumoniae in 28 of those cases (77.7%). Gram-negative bacteria were found in 7 patients (19.4%), the most common being Haemophilus influenzae in 3 patients (8.3%). The presence of atypical microorganisms was detected in 18 of the 70 patients (25%), mainly Mycobacterium pneumoniae (n=11), and in 6 cases (8.5%) the infection was mixed. Ten strains of S. pneumoniae (35.7%) were shown to be susceptible to penicillin, 2 (7.1%) were highly resistant, and 16 (57.1%) showed moderate resistance. The clinical success rate at the final visit after treatment was 94.1% for moxifloxacin and 91.7% for amoxicillin. The results of this trial demonstrate a high prevalence of S. pneumoniae with reduced susceptibility to penicillin in patients with CAP in Latin America. It also revealed a high incidence of atypical pathogens and mixed infection in 8.6% of patients. This information should be taken into account when establishing protocols for empirical treatment of CAP in Latin America.

A common clone of erythromycin-resistant Streptococcus pneumoniae in Greece and the UK

OBJECTIVE

To investigate the possible genetic relationship among erythromycin-resistant Streptococcus pneumoniae strains isolated in Greece and the UK.

METHODS

During 1995-97, 140 S. pneumoniae strains were isolated from clinical specimens submitted to the microbiology departments of the two main children's hospital in Athens. All erythromycin-resistant strains were further studied with respect to the presence of genes encoding for the two major mechanisms of macrolide resistance, their serotypes, and pulsed-field gel electrophoresis (PFGE) types, in comparison to a previously characterized UK erythromycin-resistant clone.

RESULTS

Eleven of the 140 isolates (7.9%) were resistant to erythromycin; nine of these were susceptible to penicillin. Serotyping allocated seven, three and one isolates to serotypes 14, 19F and serogroup 6, respectively. The mefA gene was detected in seven isolates (five serotype 14 and two serotype 19F), ermB in two (one serotype 19F and the serogroup 6 isolate), whilst in the remaining two isolates no resistance gene could be detected by polymerase chain reaction (PCR). Pulsed-field gel electrophoresis of genomic DNA showed that five Greek serotype 14 isolates belonged to the same chromosomal type as the serotype 14 erythromycin-resistant UK clone.

CONCLUSIONS

The present study showed that erythromycin resistance among the S. pneumoniae isolates was mostly owing to the efflux mechanism and suggested a possible clonal spread of serotype 14 erythromycin-resistant S. pneumoniae strains between Greece and the UK.

Serotype distribution and antimicrobial resistance patterns in Streptococcus pneumoniae isolates from hospitalized pediatric patients with respiratory infections in Shanghai, China

BACKGROUND

Surveillance for pneumococcal respiratory illness was conducted in children hospitalized at Affiliated Pediatric Hospital of Fudan University in Shanghai from August 2000 to August 2001.

METHODS

Sputum cultures were obtained from pediatric patients admitted with pneumonia or respiratory distress by tracheal aspirate. Blood cultures were also performed on a subset of patients. All pneumococcal isolates were serotyped and tested for antibiotic susceptibility. In addition clinical information on the patients including prior antibiotic history was abstracted. Streptococcus pneumoniae tracheal isolations were attempted in a total of 1013 pediatric patients hospitalized during this period. Among these samples 112 specimens were S. pneumoniae-positive. These positive isolates underwent serotyping and antibiotic susceptibility testing.

RESULTS

Five serotypes (19F, 23F, 6A, 14, 6B) of S. pneumonia accounted for 81% (91 of 112 cases). Other serotypes accounted only for 12% (13 of 112 cases), and 7% (8 of 112 cases) of isolates could not be typed by quelling test. Only one blood culture isolate was positive, probably reflecting the frequent use of antibiotic treatment before hospitalization. Fifty-one and 8.0% of isolates had intermediate and high level penicillin resistance, respectively. Fifty-eight percent were resistant to ampicillin, 6.6% to cefazolin, 25.0% to cefaclor, 6.6% to ceftriaxone, 85.7% to erythromycin, 66.7% to clindamycin and 28.2% to chloramphenicol. Among 66 isolates that were not susceptible to penicillin, serotype 19F was the most common, followed by 23F and 14.

CONCLUSION

S. pneumoniae is a common cause of respiratory illness requiring hospitalization in young children in Shanghai, with antibiotic resistance increasingly common. Five serotypes account for most disease.

Lack of vancomycin tolerance in Streptococcus pneumoniae strains isolated in Barcelona, Spain, from 1999 to 2001

To evaluate the incidence of vancomycin tolerance among Streptococcus pneumoniae isolates, we performed killing curve studies with 633 isolates. The penicillin MIC was > or = 0.12 mg/liter for 481 (76%) of the isolates. All strains were susceptible to vancomycin. Killing curve studies were performed with a vancomycin concentration of 2.5 mg/liter. The Tupelo strain was used for quality control. No vancomycin-tolerant strain was detected.

Geographic diversity and temporal trends of antimicrobial resistance in Streptococcus pneumoniae in the United States

Resistance of Streptococcus pneumoniae to antibiotics is increasing throughout the United States, with substantial variation among geographic regions. We show that patterns of geographic variation are best explained by the intensity of selection for resistance, which is reflected by differences between the proportions of resistance within individual serotypes, rather than by differences between the frequencies of particular serotypes. Using a mathematical transmission model, we analyzed temporal trends in the proportions of singly and dually resistant organisms and found that pneumococcal strains resistant to both penicillin and erythromycin are increasing faster than strains singly resistant to either. Using the model, we predict that by 1 July 2004, in the absence of a vaccine, 41% of pneumococci at the Centers for Disease Control and Prevention (CDC)'s Active Bacterial Core surveillance (ABCs) sites, taken together, will be dually resistant, with 5% resistant to penicillin only and 5% to erythromycin only.

Macrolide-resistant Streptococcus pneumoniae and Streptococcus pyogenes in the pediatric population in Germany during 2000-2001

In a nationwide study in Germany covering 13 clinical microbiology laboratories, a total of 307 Streptococcus pyogenes (mainly pharyngitis) and 333 Streptococcus pneumoniae (respiratory tract infections) strains were collected from outpatients less than 16 years of age. The MICs of penicillin G, amoxicillin, cefotaxime, erythromycin A, clindamycin, levofloxacin, and telithromycin were determined by the microdilution method. In S. pyogenes isolates, resistance rates were as follows: penicillin, 0%; erythromycin A, 13.7%; and levofloxacin, 0%. Telithromycin showed good activity against S. pyogenes isolates (MIC(90) = 0.25 micro g/ml; MIC range, 0.016 to 16 micro g/ml). Three strains were found to be telithromycin-resistant (MIC >/= 4 micro g/ml). Erythromycin-resistant strains were characterized for the underlying resistance genotype, with 40.5% having the efflux type mef(A), 38.1% having the erm(A), and 9.5% having the erm(B) genotypes. emm typing of macrolide-resistant S. pyogenes isolates showed emm types 4 (45.2%), 77 (26.2%), and 12 (11.9%) to be predominant. In S. pneumoniae, resistance rates were as follows: penicillin intermediate, 7.5%; penicillin resistant, 0%; erythromycin A, 17.4%; and levofloxacin, 0%. Telithromycin was highly active against pneumococcal isolates (MIC(90) </= 0.016 micro g/ml; range, 0.016 to 0.5 micro g/ml). The overall resistance profile of streptococcal respiratory tract isolates is still favorable, but macrolide resistance is of growing concern in Germany.

Bacterial resistance: origins, epidemiology, and impact

The basic mechanisms of antibacterial resistance are well known, but critical new aspects continue to be discovered. Recently discovered factors with major implications for the emergence, dissemination, and maintenance of resistance include multidrug efflux, hypermutability, integrons, and plasmid addiction. Some resistances are widespread and others local, with prevalence rates often worst in newly prosperous countries and in those specialist units where antibacterial use is heaviest. Multidrug-resistant epidemic strains are critical to the total accumulation of resistance (e.g., among Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae), but it remains unclear why some bacterial lineages achieve epidemic spread whereas others that are equally resistant do not. The correlation between in vitro resistance and treatment failure is imperfect, but resistance undoubtedly increases mortality, morbidity, and costs in many settings. Recent concern has led to a plethora of governmental and agency reports advocating less antibacterial use, better antibacterial use, better infection control, and the development of new antibacterials. The evidence that better prescribing can reduce resistance rates is mixed, and although changes to hospital regimens may reduce one resistance problem, other opportunistic bacteria may fill the vacant niche. Overall, the best that can reasonably be anticipated is an improved balance between the accumulation of resistance and new antibacterial development.

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.

Antibiotic tolerance in pneumococci

When bacteria such as Staphylococcus aureus and Streptococcus pneumoniae are exposed to lytic antibiotics such as penicillin and vancomycin, a self-induced killing process is initiated in the organism. This killing occurs via both non-lytic and lytic processes. Recent data suggest that the non-lytic killing system, which might affect the cytoplasmic membrane, secondarily activates murein hydrolases that eventually lyse the cell. Disturbances in this suicide pathway can lead to antibiotic tolerance, a process whereby the antibiotic still exerts its bacteriostatic effects but the self-induced killing system is impaired. In mutants obtained in vitro, signaling pathways have been affected that show either increased or decreased antibiotic-induced killing. Among clinical isolates of S. pneumoniae that are tolerant to penicillin and/or vancomycin, we do not yet know whether these signaling pathways are affected. We could, however, demonstrate that the activity of murein hydrolases is negatively controlled by the production of capsular polysaccharides in one vancomycin-tolerant isolate. Hence, type and level of capsular expression might constitute one factor that determines the degree of lysis, once the killing signal has been elicited by the antibiotic.