Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States

Host-derived extracellular RNA promotes adhesion of Streptococcus pneumoniae to endothelial and epithelial cells

Streptococcus pneumoniae is the most frequent cause of community-acquired pneumonia. The infection process involves bacterial cell surface receptors, which interact with host extracellular matrix components to facilitate colonization and dissemination of bacteria. Here, we investigated the role of host-derived extracellular RNA (eRNA) in the process of pneumococcal alveolar epithelial cell infection. Our study demonstrates that eRNA dose-dependently increased S. pneumoniae invasion of alveolar epithelial cells. Extracellular enolase (Eno), a plasminogen (Plg) receptor, was identified as a novel eRNA-binding protein on S. pneumoniae surface, and six Eno eRNA-binding sites including a C-terminal 15 amino acid motif containing lysine residue 434 were characterized. Although the substitution of lysine 434 for glycine (K434G) markedly diminished the binding of eRNA to Eno, the adherence to and internalization into alveolar epithelial cells of S. pneumoniae strain carrying the C-terminal lysine deletion and the mutation of internal Plg-binding motif were only marginally impaired. Accordingly, using a mass spectrometric approach, we identified seven novel eRNA-binding proteins in pneumococcal cell wall. Given the high number of eRNA-interacting proteins on pneumococci, treatment with RNase1 completely inhibited eRNA-mediated pneumococcal alveolar epithelial cell infection. Our data support further efforts to employ RNAse1 as an antimicrobial agent to combat pneumococcal infectious diseases.

Efficacy of Yeast' Vacuoles as Antimicrobial Agents to Escherichia coli Bacteremia in Rat

Yeast vacuoles, lysosomes, are cell organelles that have antimicrobial activity against several bacteria in vitro. Lysosomes have a potential application to the treatment of pathogens such as antibiotics in vivo. Therefore, the in vivo efficacy of lysosomes was examined in a rat infection model against pathogenic Escherichia coli with varying susceptibilities to standard antimicrobial agents. Before in vivo testing, the concentration-dependent safety of lysosomes was confirmed by blood test and histopathology of normal rats. The therapeutic efficacy of lysosomes was examined in terms of the survival of E. coli in infected rat blood. The complete blood count and histopathology results were affected by the lysosomes concentration. In addition, the E. coli growth was inhibited by the initial injection of lysosomes. These results support the use of lysosomes as a bacterial inhibitor of an infected rat model.

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

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

The biofilm inhibitor Carolacton inhibits planktonic growth of virulent pneumococci via a conserved target

New antibacterial compounds, preferentially exploiting novel cellular targets, are urgently needed to fight the increasing resistance of pathogens against conventional antibiotics. Here we demonstrate that Carolacton, a myxobacterial secondary metabolite previously shown to damage Streptococcus mutans biofilms, inhibits planktonic growth of Streptococcus pneumoniae TIGR4 and multidrug-resistant clinical isolates of serotype 19A at nanomolar concentrations. A Carolacton diastereomer is inactive in both streptococci, indicating a highly specific interaction with a conserved cellular target. S. mutans requires the eukaryotic-like serine/threonine protein kinase PknB and the cysteine metabolism regulator CysR for susceptibility to Carolacton, whereas their homologues are not needed in S. pneumoniae, suggesting a specific function for S. mutans biofilms only. A bactericidal effect of Carolacton was observed for S. pneumoniae TIGR4, with a reduction of cell numbers by 3 log units. The clinical pneumonia isolate Sp49 showed immediate growth arrest and cell lysis, suggesting a bacteriolytic effect of Carolacton. Carolacton treatment caused a reduction in membrane potential, but not membrane integrity, and transcriptome analysis revealed compensatory reactions of the cell. Our data show that Carolacton might have potential for treating pneumococcal infections.

Immunization Rates and Beliefs among Elderly Patients of Inner City Neighborhood Health Centers

Although influenza and pneumonia are the sixth leading cause of death in the United States, immunization rates are modest and racial disparity occurs. To address this issue, the authors surveyed 220 of 261 contacted persons aged ≥ 66 years old who were randomly selected from inner city neighborhood health centers in Pittsburgh. The authors conducted computer assisted telephone interviewing using a standard questionnaire based on the theory of reasoned action. Influenza vaccination rates were 60% for Blacks and 79% for Whites, and varied from 59% to 81% by health center. Vaccination rates against pneumococcus were 59% for Blacks and 70% for Whites. No significant racial differences were found in report of experiencing influenza or in beliefs about the diseases and vaccines. Blacks were less likely than Whites to perceive that their doctor thought they should be vaccinated against influenza (83% vs. 93%, p = .02). Blacks were somewhat more likely than Whites to report that pneumococcal polysaccharide vaccination was more trouble than it was worth (21% vs. 10%, p = .02). Because factors related to social influences and facilitating conditions are associated with vaccination status and because immunization rates vary by medical center, the authors recommend enhancing immunization efforts within the health centers.

Patterns of Macrolide Resistance Determinants among S. pyogenes and S. pneumoniae Isolates in Saudi Arabia

In the study we characterized the macrolide sensitivity of recent clinical isolates of Streptococcus pyogenes and S. pneumoniae collected from major Saudi Arabian hospitals. Susceptibility testing was performed using standard National Committee for Clinical Laboratory Standards methodology on 335 S. pyogenes and 350 S. pneumoniae isolates. Macrolide resistance mechanism phenotypes were identified using double-disk diffusion. All S. pyogenes were penicillin sensitive, while 6.3% were macrolide resistant, the main mechanism of which was of M phenotype (96%). Approximately 51% of S. pneumoniae were penicillin non-susceptible. Macrolide resistance in S. pneumoniae accounted for 18.8%, the majority of which were M phenotype (91%). Low-level resistance mediated by mef-bearing strains predominated. Newer macrolides, including azithromycin, are still considered drugs of choice for empirical treatment of respiratory infection in such circumstances.

Use of Local Community Hospital Data for Surveillance of Antimicrobial Resistance

We sought to determine whether antimicrobial susceptibility data from a nonteaching community hospital could be used to detect statistically significant local increases in resistance among Streptococcus pneumoniae over a 5-year period. Minimum inhibitory concentrations (MICs) of penicillin and ceftriaxone from 1997-1998 were compared with those from 2000-2001. MICs of penicillin and ceftriaxone for organisms collected in a nonteaching community hospital in central Illinois were used for analysis. The hospital has 224 beds and a catchment area of approximately 40 miles. There were significant increases in MICs of penicillin and ceftriaxone between 1997-1998 and 2000-2001. The MIC of penicillin increased from 0.042 to 0.121 μg/mL (P = .001; 95% confidence interval, -1.713 to -0.388), and the MIC of ceftriaxone increased from 0.028 to 0.071μg/mL (P = .005; 95% confidence interval, -1.353 to -0.188). There were no significant changes in the percentage of S. pneumoniae isolates that were resistant, intermediate, or susceptible to penicillin and ceftriaxone. MIC data from a community hospital can be used to detect local increases in the rate of resistance before antibiogram data show significant changes. This information is important for demonstrating to physicians the need to review local antibiotic use in the attempt to slow the development of resistant organisms in the community.

Failure to Control an Outbreak of Multidrug-ResistantStreptococcus pneumoniaein a Long-Term–Care Facility Emergence and Ongoing Transmission of a Fluoroquinolone-Resistant Strain

Objectives:

To characterize risk factors associated with pneumococcal disease and asymptomatic colonization during an outbreak of multidrug-resistantStreptococcus pneumoniae(MDRSP) among AIDS patients in a long-term–care facility (LTCF), evaluate the efficacy of antimicrobial prophylaxis in eliminating MDRSP colonization, and describe the emergence of fluoroquinolone resistance in the MDRSP outbreak strain.

Design:

Epidemiologic investigation based on chart review and characterization of SP strains by antimicrobial susceptibility testing and PFGE and prospective MDRSP surveillance.

Setting:

An 80-bed AIDS-care unit in an LTCF.

Participants:

Staff and residents on the unit.

Results:

From April 1995 through January 1996, 7 cases of MDRSP occurred. A nasopharyngeal (NP) swab survey of all residents (n = 65) and staff (n = 70) detected asymptomatic colonization among 6 residents (9%), but no staff. Isolates were sensitive only to rifampin, ofloxacin, and vancomycin. A 7-day course of rifampin and ofloxacin was given to eliminate colonization among residents: NP swab surveys at 1, 4, and 10 weeks after prophylaxis identified 1 or more colonized residents at each follow-up with isolates showing resistance to one or both treatment drugs. Between 1996 and 1999, an additional 6 patients were diagnosed with fluoroquinolone-resistant (FQ-R) MDRSP infection, with PFGE results demonstrating that the outbreak strain had persisted 3 years after the initial outbreak was recognized.

Conclusions:

Chemoprophylaxis likely contributed to the development of a FQ-R outbreak strain that continued to be transmitted in the facility through 1999. Long-term control of future MDRSP outbreaks should rely primarily on vaccination and strict infection control measures.

Overcoming Barriers to Establishing an Inpatient Vaccination Program for Pneumococcus Using Standing Orders

Objectives:

To identify and classify barriers to establishing a standing orders program (SOP) for adult pneumococcal vaccination in acute care inpatient facilities and to provide recommendations for overcoming these roadblocks. Vaccination rates in hospitals with SOPs are generally higher than those in hospitals that require individual physician orders. The array of solutions drawn from our experience in different hospital settings should permit many types of facilities to anticipate and overcome barriers, allowing a smoother transition from initiation to successful implementation of an inpatient pneumococcal vaccination SOP.

Design:

Descriptive study of barriers and solutions encountered during implementation of a pneumococcal vaccination SOP in three hospitals of the University of Pittsburgh Medical Center Health System (UPMC) and in the scientific literature.

Setting:

As of 2004, two UPMC tertiary-care hospitals and one UPMC community hospital had incorporated SOPs into existing physician order-driven programs for inpatient vaccination with pneumococcal polysaccharide vaccine.

Results:

Barriers were identified at each step of implementation and categorized as patient related, provider related, or institutional. Based on a process of continual review and revision of our programs in response to encountered barriers, steps were taken to overcome these impediments.

Conclusions:

A strong commitment by key individuals in the facility's administration including a physician champion; ongoing, persistent efforts to educate and train staff; and close monitoring of the vaccination rate were essential for successful implementation of a SOP for pneumococcal vaccination of eligible inpatients. Legal statutes and evaluations of external hospital-rating associations regarding the effectiveness of the vaccination program were major motivating factors in its success.

Immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years: A randomized, double-blinded, active control, phase III trial

Streptococcus pneumoniae is an important pathogen causing invasive diseases such as sepsis, meningitis, and pneumonia. Vaccines have become the most effective way to prevent pneumococcal infections. This phase III trial was designed to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine in Chinese healthy population aged >2 years. We conducted a randomized, double-blinded, active-controlled, multicenter trial in which 1660 healthy population (>2 years of age) were randomly assigned in a 1 : 1 ratio to receive 2 intramuscular doses of either the treatment vaccine or the active control vaccine, PNEUMOVAX 23. The surveillance period was 30 days. The primary end point was the 2-fold increase rate of anti-pneumococcal antibody for all 23 included serotypes in each group. In the intention-to-treat cohort, the 2-fold increase rate of anti-pneumococcal antibody for 23 included serotypes varied from 62.47% to 97.01% in the treatment group, and from 51.49% to 95.77% in the control group. According to -10% non-inferiority margin and 95% confidence intervals of rate difference, almost all included serotypes of the treatment group reached non-inferiority to control group except for serotype 6B, the lower limit of rate difference of which was -10.00%, equal to the non-inferiority margin. The 2-fold increase rates of anti-pneumococcal antibody were significantly higher in the treatment group for serotype 2, 3, 4, 10A, 11A and 20. Furthermore, for all 23 serotypes, IgG geometric mean concentrations (GMCs) at day 30 were significantly higher in treatment group for serotype 2, 3, 4, 9 V, 10A, 11A, 15 B, 18C, 19 A, 22 F and 33 F. Higher geometric mean fold increase (GMFI) were also observed in the treatment group correspondingly. Serious adverse events occurred in 3 of 830 participants in the treatment group (0.36%) and 2 of 830 participants in the control group (0.24%). No death occurred during the trial. The frequencies of both solicited and unsolicited adverse events (AEs) were small lower in the treatment group (34.34% vs 35.66% for solicited AEs, 4.34% vs 5.42% for unsolicited AEs). Both vaccines were well tolerated and most AEs were mild or moderate in intensity. The newly vaccine was well tolerated and immunologically non-inferior to the active control vaccine PNEUMOVAX 23 for all 23 vaccine serotypes in the Chinese population (>2 years of age).

Nationwide survey of Streptococcus pneumoniae drug resistance in the pediatric field in Japan

BACKGROUND

Streptococcus pneumoniae is a major causative pathogen of pneumonia in children. The Drug-Resistant Pathogen Surveillance Group in Pediatric Infectious Disease conducted a nationwide surveillance of S. pneumoniae in 2000-2001, 2004, 2007, 2010 and 2012, and investigated changes in drug resistance of S. pneumoniae.

METHODS

All strains of S. pneumoniae were isolated from clinical specimens collected from pediatric patients. The minimun inhibitory concentration was measured and the strains were classified according to the Clinical Laboratory Standards Institute criteria. The isolation rates of penicillin-intermediate resistant S. pneumoniae (PISP) and penicillin-resistant S. pneumoniae (PRSP) were compared based on seven patient factors. Logistic regression analysis was also performed.

RESULTS

The sum of the isolation rates for PISP and PRSP for each period was 64.6%, 67.0%, 56.2%, 76.9% and 49.5%, respectively. Among the patient factors, age category 1 (<3 years, ≥3 years), age category 2 (infant, toddler and preschooler, schoolchild), siblings (absence, presence), and pre-treatment with antimicrobial agents (absence, presence) were associated with significant differences in the isolation rate of PISP + PRSP. An interaction was observed between pre-treatment with antimicrobial agents and schoolchild, and the isolation rate of PISP + PRSP was higher in patients with both pre-treatment with antimicrobial agents and schoolchild.

CONCLUSION

Although some changes were observed in the rate of resistance of S. pneumoniae, an increasing trend was not observed. Both pre-treatment with antimicrobial agents and age were associated with resistance, and an interaction was observed between pre-treatment with antimicrobial agents and schoolchild.

Infektionen des ZNS

Viren, Bakterien, Protozoen, Helminthen und Pilze können, sofern es ihnen gelingt, die Blut-Hirn-Schranke zu überwinden, ZNS und gelegentlich das periphere Nervensystem involvieren; Meningitis, Enzephalitis, Hirnabszess, Meningovaskulitis oder granulomatöse Prozesse sind potenzielle Folgen.

ucFabV Requires Functional Reductase Activity to Confer Reduced Triclosan Susceptibility in Escherichia coli

BACKGROUND/AIMS

We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in Escherichia coli. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positions that would predict differences in substrate binding. Therefore, a detailed characterization of ucFabV was conducted to link its biochemical activity to its ability to confer reduced triclosan sensitivity.

METHODS

ucFabV and a catalytic mutant were purified and used to reduce crotonoyl-CoA in vitro. The mutant and wild-type enzymes were introduced into E. coli, and their ability to confer triclosan tolerance as well as suppress a temperature-sensitive mutant of FabI were measured.

RESULTS

Purified ucFabV, but not the mutant, reduced crotonoyl-CoA in vitro. The wild-type enzyme confers increased triclosan tolerance when introduced into E. coli, whereas the mutant remained susceptible to triclosan. Additionally, wild-type ucFabV, but not the mutant, functionally replaced FabI within living cells.

CONCLUSION

ucFabV confers increased tolerance through its function as an enoyl-ACP reductase. Furthermore, ucFabV is capable of restoring viability in the presence of compromised FabI, suggesting ucFabV is likely facilitating an alternate step within fatty acid synthesis, bypassing FabI inhibition.

Antibiotic resistance of Streptococcus pneumoniae in children with acute otitis media treatment failure

OBJECTIVES

The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with acute otitis media (AOM). This study aimed to analyze the types of bacterial strains in fluid isolated from the middle ear of children with AOM who did not respond to oral antibiotic treatment. We also determined the antibiotic resistance of the most frequently isolated bacterial strain (Streptococcus pneumoniae) found in these children.

METHODS

This was a prospective study of 157 children with AOM aged from 6 months to 7 years admitted due to unsuccessful oral antibiotic treatment. All children underwent a myringotomy, and samples of the middle ear fluid were collected for bacteriological examination.

RESULTS

Positive bacterial cultures were obtained in 104 patients (66.2%), with Streptococcus pneumoniae (39.69%), Haemophilus influenzae (16.03%) Staphylococcus aureus (16.03%), Staphylococcus haemolyticus (6.9%) and Streptococcus pyogenes (5.34%) found most frequently. The majority (65.4%) of S. pneumoniae strains were penicillin-intermediate-resistant or penicillin-resistant, and 67.2% strains of S. pneumoniae were multidrug-resistant.

CONCLUSIONS

We identified S. pneumoniae as the most frequently isolated pathogen from the middle ear in children with AOM treatment failure and determined that the majority of strains were antibiotic-resistant. We propose that the microbiological identification of bacterial strains and their degree of antibiotic resistance should be performed prior to therapy in order to choose the most appropriate antibiotic therapy for children with AOM treatment failure.

Emerging Infections Program as Surveillance for Antimicrobial Drug Resistance

Across the United States, antimicrobial drug-resistant infections affect a diverse population, and effective interventions require concerted efforts across various public health and clinical programs. Since its onset in 1994, the Centers for Disease Control and Prevention Emerging Infections Program has provided robust and timely data on antimicrobial drug-resistant infections that have been used to inform public health action across a spectrum of partners with regard to many highly visible antimicrobial drug-resistance threats. These data span several activities within the Program, including respiratory bacterial infections, health care-associated infections, and some aspects of foodborne diseases. These data have contributed to estimates of national burden, identified populations at risk, and determined microbiological causes of infection and their outcomes, all of which have been used to inform national policy and guidelines to prevent antimicrobial drug-resistant infections.

Twenty Years of Active Bacterial Core Surveillance

Active Bacterial Core surveillance (ABCs) was established in 1995 as part of the Centers for Disease Control and Prevention Emerging Infections Program (EIP) network to assess the extent of invasive bacterial infections of public health importance. ABCs is distinctive among surveillance systems because of its large, population-based, geographically diverse catchment area; active laboratory-based identification of cases to ensure complete case capture; detailed collection of epidemiologic information paired with laboratory isolates; infrastructure that allows for more in-depth investigations; and sustained commitment of public health, academic, and clinical partners to maintain the system. ABCs has directly affected public health policies and practices through the development and evaluation of vaccines and other prevention strategies, the monitoring of antimicrobial drug resistance, and the response to public health emergencies and other emerging infections.

New issues in bacterial meningitis in adults

The epidemiologic factors of bacterial meningitis, a serious disease that must be addressed with great urgency, have evolved dramatically in the last 25 years. Among both adults and children, multidrug-resistant Streptococcus pneumoniae has emerged as a clinical challenge and has greatly complicated the empirical management of this disease. In this article, the author focuses on new issues involving the epidemiologic factors, diagnosis, treatment, and prevention of bacterial meningitis in adults.

Antimicrobial Susceptibility Pattern of Invasive Pneumococcal Isolates in North West Nigeria

BACKGROUND

An alarming increase in infections due to penicillin non-susceptible pneumococci (PNSP) has been documented in nearly all countries. Increasingly, PNSP are also resistant to other antibiotics, and a growing number of clinical failures following the use of these agents have been reported.

AIMS

To determine the resistance pattern of pneumococcal isolates from patients with invasive pneumococcal infection in North West Nigeria.

MATERIALS AND METHODS

In a cross-sectional study clinical specimens were obtained from patients with community acquired pneumonia (CAP), meningitis and bacteraemia over a 2 year period. Pneumococcus strains were identified. Isolates were tested against a panel of antibiotics using E-test strips, and interpreted according to the CLSI criteria. 0.06 μg/ml was used as break point for penicillin. Analysis was carried out using descriptive statistics; relationships determined using chi-squared or Fisher's exact tests, with P < 0.05 regarded as significant.

RESULTS

Total number of isolates was 132. Twenty-two (16.7%) of the isolates were fully sensitive to penicillin while 73 (55.3%) and 37 (28.0%) were intermediately and fully resistant, respectively. One hundred and twenty-seven (96.2%) of the isolates were fully resistant to trimethoprim-sulphamethoxazole. Eleven (8.5%) were fully resistant to amoxicillin and 104 (78.8%) and 17 (12.9%) were intermediately resistant and fully susceptible. One hundred and six (80.3%) of the isolates were fully susceptible to chloramphenicol. Resistance to penicillin was shown to infer resistance to other antibiotics.

CONCLUSIONS

Pneumococcal resistance is common in North West Nigeria. Ceftriaxone retains excellent activity against most of the invasive isolate, while trimethoprim-sulphamethoxazole is almost uniformly resistant.

Changes in capsule and drug resistance of Pneumococci after introduction of PCV7, Japan, 2010-2013

We aimed to clarify changes in serotypes and genotypes mediating β-lactam and macrolide resistance in Streptococcus pneumoniae isolates from Japanese children who had invasive pneumococcal disease (IPD) after the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into Japan; 341 participating general hospitals conducted IPD surveillance during April 2010-March 2013. A total of 300 pneumococcal isolates were collected in 2010, 146 in 2011, and 156 in 2012. The proportion of vaccine serotypes in infectious isolates decreased from 73.3% to 54.8% to 14.7% during the 3 years. Among vaccine serotype strains, genotypic penicillin-resistant S. pneumoniae strains also declined each year. Among nonvaccine serotype strains, 19A, 15A, 15B, 15C, and 24 increased in 2012. Increases were noted especially in genotypic penicillin-resistant S. pneumoniae isolates of serotypes 15A and 35B, as well as macrolide resistance mediated by the erm(B) gene in 15A, 15B, 15C, and 24.

Bacterial etiology of acute otitis media and characterization of pneumococcal serotypes and genotypes among children in Moscow, Russia

BACKGROUND

We aimed to describe bacterial etiology of acute otitis media (AOM) and characterize resistance, serotypes and genotype profiles of AOM-causing pneumococci recovered in Moscow children.

METHODS

Children with AOM and an available middle ear fluid specimen were prospectively enrolled in this study. Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis were considered as true otopathogens. All pneumococcal isolates were serotyped using the Quellung reaction; multidrug-resistant (MDR) pneumococci underwent multilocus sequence typing.

RESULTS

In 172 of 541 enrolled AOM patients (32%) at least 1 otopathogen was recovered, with S. pneumoniae having the highest rate of 63% (109/172). When adjusted for antibiotic treatment before sampling, in untreated patients the rate of culture-positive AOM was 35% (124/352), S. pneumoniae had a prevalence of 69% (86/124), S. pyogenes 19% (24/124), H. influenzae 13% (16/124) and M. catarrhalis 9% (11/124). Among 107 examined pneumococci, 45% were penicillin-nonsusceptible, 34 and 30% were resistant to erythromycin and clindamycin, respectively; 30% had an MDR phenotype, but no amoxicillin-resistant isolates were found. Ten of 32 (31%) MDR pneumococci related to clonal complex 320, the remaining isolates belonged to 7 different clonal complex. Six leading serotypes were 19F (27%), 3 (12%), 6B (11%), 14 (11%), 19A (9%) and 23F (8%); overall polysaccharide conjugate vaccine13 coverage was 93%.

CONCLUSIONS

S. pneumoniae, the leading bacterial AOM pathogen in Moscow children, is characterized by a substantial rate of antibiotic nonsusceptibility and clonality. A polysaccharide conjugate vaccine with expanded coverage seems to fit the current AOM pneumococcal serotype distribution in Russia better.

Phenotypic and functional analysis of HL-60 cells used in opsonophagocytic-killing assay for Streptococcus pneumoniae

Differentiated HL-60 is an effector cell widely used for the opsonophagocytic-killing assay (OPKA) to measure efficacy of pneumococcal vaccines. We investigated the correlation between phenotypic expression of immunoreceptors and phagocytic ability of HL-60 cells differentiated with N,N-dimethylformamide (DMF), all-trans retinoic acid (ATRA), or 1α, 25-dihydroxyvitamin D3 (VitD3) for 5 days. Phenotypic change was examined by flow cytometry with specific antibodies to CD11c, CD14, CD18, CD32, and CD64. Apoptosis was determined by flow cytometry using 7-aminoactinomycin D. Function was evaluated by a standard OPKA against serotype 19F and chemiluminescence-based respiratory burst assay. The expression of CD11c and CD14 gradually increased upon exposure to all three agents, while CD14 expression increased abruptly after VitD3. The expression of CD18, CD32, and CD64 increased during differentiation with all three agents. Apoptosis remained less than 10% until day 3 but increased after differentiation by DMF or ATRA. Differentiation with ATRA or VitD3 increased the respiratory burst after day 4. DMF differentiation showed a high OPKA titer at day 1 which sustained thereafter while ATRA or VitD3-differentiated cells gradually increased. Pearson analysis between the phenotypic changes and OPKA titers suggests that CD11c might be a useful differentiation marker for HL-60 cells for use in pneumococcal OPKA.

Pharmacokinetic and pharmacodynamic evaluation of ceftaroline fosamil

INTRODUCTION

Ceftaroline fosamil is a 5th generation cephalosporin with an in vitro spectrum of activity including Streptococcus agalactiae, penicillin- and cephalosporin-resistant S. pneumoniae, S. pyogenes, methicillin-susceptible S. aureus and methicillin-resistant S. aureus, Haemophilus influenzae, Klebsiella oxytoca, K. pneumoniae and Moraxella catarrhalis. It is currently approved by the FDA for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) in adults.

AREAS COVERED

This review covers the mechanism of action; bacterial resistance; pharmacokinetic characteristics in various patient populations; pharmacodynamic data in animal and in vitro models as well as human studies; efficacy observed in clinical trials for ABSSSI and CABP; and adverse effects.

EXPERT OPINION

Ceftaroline provides in vitro bactericidal activity against methicillin-, vancomycin-, daptomycin-, and linezolid-resistant Gram-positive organisms and select Gram-negative pathogens. The pharmacodynamics of ceftaroline is similar to other β-lactam agents. Ceftaroline exhibits a favorable adverse effect profile and is generally well tolerated. There is little data on clinical success of ceftaroline in patients with bacteremia or endocarditis other than what has been published in a small series of case reports. Randomized-control studies are needed to establish clinical outcomes and safety in these patient populations.

Natural transformation and genome evolution in Streptococcus pneumoniae

Streptococcus pneumoniae is a frequent colonizer of the human nasopharynx that has the potential to cause severe infections such as pneumonia, bacteremia and meningitis. Despite considerable efforts to reduce the burden of pneumococcal disease, it continues to be a major public health problem. After the Second World War, antimicrobial therapy was introduced to fight pneumococcal infections, followed by the first effective vaccines more than half a century later. These clinical interventions generated a selection pressure that drove the evolution of vaccine-escape mutants and strains that were highly resistant against antibiotics. The remarkable ability of S. pneumoniae to acquire drug resistance and evade vaccine pressure is due to its recombination-mediated genetic plasticity. S. pneumoniae is competent for natural genetic transformation, a property that enables the pneumococcus to acquire new traits by taking up naked DNA from the environment and incorporating it into its genome through homologous recombination. In the present paper, we review current knowledge on pneumococcal transformation, and discuss how the pneumococcus uses this mechanism to adapt and survive under adverse and fluctuating conditions.

Changes in pneumococcal serotypes and antimicrobial resistance after introduction of the 13-valent conjugate vaccine in the United States

Ongoing surveillance for Streptococcus pneumoniae is needed to assess the impact of the pneumococcal conjugate vaccine introduced in 2010 (PCV13). Forty-two U.S. centers submitted S. pneumoniae isolates between 1 October 2012 and 31 March 2013. Susceptibility testing was performed by use of a broth dilution method as recommended by the Clinical and Laboratory Standards Institute. Serotyping was performed by multiplex PCR and the Quellung reaction. Multidrug resistance (MDR) was defined as nonsusceptibility to penicillin (PNSP; MIC ≥ 0.12 μg/ml) combined with resistance to ≥2 non-β-lactam antimicrobials. Penicillin-resistant S. pneumoniae (PRSP) was defined as a penicillin MIC of ≥2 μg/ml. For the 1,498 isolates collected during 2012-13, the PRSP and MDR rates were 14.2 and 21.0%, respectively. These percentages were lower than rates obtained in a surveillance study conducted 4 years earlier in 2008-09 (17.0 and 26.6%, respectively). The most common serotypes identified in 2012-13 were 3, 35B, and 19A, each representing 9 to 10% of all isolates. The largest percentage of PNSP in 2012-13 were found in serotypes 35B (24.8%), 19A (23.5%), and 15A (10.3%). Predominant PRSP serotypes were 19A (54.5%), 35B (28.2%), and 19F (7.0%). Major MDR serotypes were 19A (38.5%), 15A (16.9%), 6C (8.3%), and 35B (6.4%). The change in prevalence of PCV13 serotypes (43.4 to 27.1%) was primarily due to a decrease in serotype 19A strains, i.e., 22% of all strains in 2008-09 to 10% of all strains in 2012-13. Among the PNSP subset, serotypes showing a proportional increase were 35B, 15B, and 23B. Among MDR strains, the largest proportional increases were observed in serotypes 35B, 15B, and 23A.

Nasopharyngeal carriage of Streptococcus pneumoniae in Romanian children before the introduction of the pneumococcal conjugated vaccination into the national immunization programme: a national, multi-centre, cross-sectional observational study

OBJECTIVES

We analysed the distribution of vaccine and non-vaccine Streptococcus pneumoniae serotypes and the antimicrobial susceptibility of pneumococcal strains isolated from healthy Romanian children.

METHODS

A multi-centre cross-sectional study was performed in four counties to evaluate carried strains of S. pneumoniae isolated from 2000 children aged 0-5 years.

RESULTS

S. pneumoniae carriage was detected in 25.25% of the tested children. Carriage increased from 16.7% among infants to 29.4% in 3-5-year-old children (p<0.0001). The proportions of the serotypes included in pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 among our isolates were 39.9%, 40.1%, and 58.7%, respectively. Erythromycin resistance was 72.5%, and it was significantly lower in non-vaccine serotypes compared with PCV13 serotypes: 57.3% versus 83.6% (p<10(-7)). Penicillin minimum inhibitory concentrations (MICs) >0.064mg/l were recorded in 71.6%, but the penicillin MIC was >2mg/l for only 8.4% of tested isolates.

CONCLUSIONS

In Romanian children, the majority of carried S. pneumoniae isolates are vaccine serotypes. The isolates with MICs defining macrolide resistance were very frequent, as well as the isolates with MICs defining penicillin resistance in the case of meningitis or penicillin dose-dependent susceptibility for other infections, mainly for the strains belonging to PCV13 serotypes. The implementation of PCV13 within the Romanian national immunization programme could reduce the circulation of these strains with higher macrolide and/or penicillin MICs.

Antimicrobial Susceptibilities and Distribution of Resistance Genes for β-Lactams in Streptococcus pneumoniae Isolated in Hamadan

BACKGROUND

β-lactams resistant Streptococcus pneumoniae are an emerging problem throughout the world. Several resistance mechanisms have been reported, including expression of drug-destroying enzymes such as β-lactamases, altered drug targets such as conformational changes in PBPs, decreased bacterial permeability, and increased drug efflux.

OBJECTIVES

The present study aimed to determine the relationship between the results of polymerase chain reaction identification of the Pbp1a, Pbp2b and Pbp2x genes (penicillin-binding proteins) and susceptibilities of β-lactam antibiotics against S. pneumoniae.

MATERIALS AND METHODS

Fifty five isolates of S. pneumoniae were obtained from clinical samples with antimicrobial tests. The susceptibilities of isolates to benzylpenicillin, imipenem, oxacillin, ceftazidime were determined. The resistance genotype was determined by the polymerase chain reaction with primers designed for the PBP genes.

RESULTS

The number of S. pneumoniae isolates resistant to benzylpenicillin, imipenem, oxacillin and ceftazidime were 94.5%, 100%, 100%, and 21.8%, respectively. Analysis of mutation in the genes for pbp showed that 85% of isolates had mutations in pbp2x, pbp2b and pbp1a. Susceptibility to benzylpenicillin was decreased once the number of mutated pbp genes in S. pneumonia increased. According to the results of this study, S. pneumoniae isolates showed reduced susceptibility due to accumulation of resistance genes.

CONCLUSIONS

We suggest that studies should be performed to evaluate changes in Minimum Inhibitory Concentration (MIC) values as well as genetic mutations in order to determine prevalence of S. pneumoniae resistance against antimicrobial agents.

Invasive pneumococcal disease after implementation of 13-valent conjugate vaccine

OBJECTIVE

To examine whether there is a different clinical profile and severity of invasive pneumococcal disease (IPD) in children caused by nonvaccine types in the era of 13-valent pneumococcal conjugate vaccine (PCV13).

METHODS

Observational study of childhood IPD in Massachusetts based on state public health surveillance data comparing pre-PCV13 (2007-2009) and post-PCV13 (2010-2012) eras.

RESULTS

There were 168 pre-PCV13 cases of IPD and 85 post-PCV13 cases of IPD in Massachusetts children ≤5 years of age. PCV13 serotypes declined by 18% in the first 2 years after PCV13 use (P = .011). In the post-PCV13 phase, a higher proportion of children were hospitalized (57.6% vs. 50.6%), and a higher proportion of children had comorbidity (23.5% vs. 19.6%). Neither difference was statistically significant, nor were comparisons of IPD caused by vaccine and nonvaccine types. Children with comorbidities had higher rates of IPD caused by a nonvaccine type (27.6% vs. 17.2%; P = .085), were more likely to be hospitalized (80.4% vs. 50%; P < .0001), and were more likely to have a longer hospital stay (median of 3 days vs. 0.5 days; P = .0001).

CONCLUSIONS

Initial data suggest that nonvaccine serotypes are more common in children with underlying conditions, who have greater morbidity from disease. In the post-PCV13 era, a larger proportion of patients are hospitalized, but mortality rates are unchanged. Routine vaccination with PCV13 may not be enough to reduce the risk in patients with comorbidity.

A novel protein, RafX, is important for common cell wall polysaccharide biosynthesis in Streptococcus pneumoniae: implications for bacterial virulence

Teichoic acid (TA), together with peptidoglycan (PG), represents a highly complex glycopolymer that ensures cell wall integrity and has several crucial physiological activities. Through an insertion-deletion mutation strategy, we show that ΔrafX mutants are impaired in cell wall covalently attached TA (WTA)-PG biosynthesis, as evidenced by their abnormal banding patterns and reduced amounts of WTA in comparison with wild-type strains. Site-directed mutagenesis revealed an essential role for external loop 4 and some highly conserved amino acid residues in the function of RafX protein. The rafX gene was highly conserved in closely related streptococcal species, suggesting an important physiological function in the lifestyle of streptococci. Moreover, a strain D39 ΔrafX mutant was impaired in bacterial growth, autolysis, bacterial division, and morphology. We observed that a strain R6 ΔrafX mutant was reduced in adhesion relative to the wild-type R6 strain, which was supported by an inhibition assay and a reduced amount of CbpA protein on the ΔrafX mutant bacterial cell surface, as shown by flow cytometric analysis. Finally, ΔrafX mutants were significantly attenuated in virulence in a murine sepsis model. Together, these findings suggest that RafX contributes to the biosynthesis of WTA, which is essential for full pneumococcal virulence.

Evidence for soft selective sweeps in the evolution of pneumococcal multidrug resistance and vaccine escape

The multidrug-resistant Streptococcus pneumoniae Taiwan(19F)-14, or PMEN14, clone was first observed with a 19F serotype, which is targeted by the heptavalent polysaccharide conjugate vaccine (PCV7). However, "vaccine escape" PMEN14 isolates with a 19A serotype became an increasingly important cause of disease post-PCV7. Whole genome sequencing was used to characterize the recent evolution of 173 pneumococci of, or related to, PMEN14. This suggested that PMEN14 is a single lineage that originated in the late 1980s in parallel with the acquisition of multiple resistances by close relatives. One of the four detected serotype switches to 19A generated representatives of the sequence type (ST) 320 isolates that have been highly successful post-PCV7. A second produced an ST236 19A genotype with reduced resistance to β-lactams owing to alteration of pbp1a and pbp2x sequences through the same recombination that caused the change in serotype. A third, which generated a mosaic capsule biosynthesis locus, resulted in serotype 19A ST271 isolates. The rapid diversification through homologous recombination seen in the global collection was similarly observed in the absence of vaccination in a set of isolates from the Maela refugee camp in Thailand, a collection that also allowed variation to be observed within carriage through longitudinal sampling. This suggests that some pneumococcal genotypes generate a pool of standing variation that is sufficiently extensive to result in "soft" selective sweeps: The emergence of multiple mutants in parallel upon a change in selection pressure, such as vaccine introduction. The subsequent competition between these mutants makes this phenomenon difficult to detect without deep sampling of individual lineages.

Factors associated with ceftriaxone nonsusceptibility of Streptococcus pneumoniae: analysis of South African national surveillance data, 2003 to 2010

It is important to monitor β-lactam antimicrobial nonsusceptibility trends for Streptococcus pneumoniae to inform empirical treatment guidelines. In this study, we describe penicillin and ceftriaxone susceptibility trends using national laboratory-based pneumococcal surveillance data from 2003 to 2010. A sentinel enhanced-site patient subset (2009 to 2010) contributed to the risk factor and mortality analyses. We included 9,218 invasive pneumococcal disease (IPD) cases for trend analyses and 2,854 IPD cases for risk factor and mortality analyses. Overall, we detected no significant changes in penicillin (patients <5 years of age, P = 0.50; patients ≥ 5 years of age, P = 0.05) or ceftriaxone nonsusceptibility rates (patients <5 years of age, P = 0.21; patients ≥ 5 years of age, P = 0.60). Factors associated with ceftriaxone nonsusceptibility on multivariate analysis were an age of <5 years (<1 year of age: adjusted odds ratio [aOR], 2.87; 95% confidence interval [CI], 1.70 to 4.86; 1 to 4 years of age: aOR, 2.58; 95% CI, 1.53 to 4.35, versus 25 to 44 years of age), province (Gauteng [aOR, 2.46; 95% CI, 1.26 to 4.84], and Northern Cape [aOR, 4.52; 95% CI, 1.95 to 10.52] versus KwaZulu-Natal), β-lactam use within 24 h preceding admission (aOR, 2.52; 95% CI, 1.41 to 4.53), and 13-valent vaccine serotypes (aOR, 51.64; 95% CI, 7.18 to 371.71). Among patients ≥ 5 years of age with meningitis who were treated according to current guidelines, HIV-infected patients (aOR, 2.94; 95% CI, 1.32 to 6.54) and patients infected with ceftriaxone-nonsusceptible isolates (aOR, 3.17; 95% CI, 1.27 to 7.89) had increased mortality rates. Among children <5 years of age with meningitis, mortality was increased in HIV-infected patients (aOR, 3.04; 95% CI, 1.40 to 6.56) but not in those with ceftriaxone-nonsusceptible isolates. Penicillin and ceftriaxone nonsusceptibility remained stable over the study period. Ceftriaxone nonsusceptibility was associated with increased mortality among patients ≥5 years of age with meningitis. The introduction of a pneumococcal conjugate vaccine may reduce ceftriaxone-nonsusceptible meningitis.

Cardiopulmonary morbidity of streptococcal infections in a PICU

AIM

The streptococci are important bacteria that cause serious childhood infections. We investigated cardiopulmonary morbidity associated with streptococcal infection and pediatric intensive care unit (PICU) admission.

METHODS

A retrospective study between 2002 and 2013 of all children with a laboratory isolation of streptococcus.

RESULTS

There were 40 (2.3%) PICU patients with streptococcal isolations including Streptococcus pyogenes (Group A streptococcus, GAS, n = 7), Streptococcus agalactiae (Group B streptococcus, GBS, n = 5), Streptococcus pneumoniae (SP, n = 20), alpha-hemolytic (n = 4), beta-hemolytic (n = 2) and gama-hemolytic (n = 2) streptococci. Comparing among GAS, GBS and SP, respiratory isolates were more likely positive for GAS or SP (P = 0.033), whereas cerebrospinal fluid was more likely positive for GBS (P = 0.002). All GAS and GBS, and the majority of SP (90%) were sensitive to penicillin. All SP specimens were sensitive to cefotaxime and vancomycin. These infections were associated with high PICU mortality of 43%, 20% and 25%, respectively. Isolation of streptococci was associated with a 30% mortality and high rates of need for mechanical ventilatory and inotropic supports. Patients with GAS, SP or any streptococcal isolation had relative risks [95% confidence interval (CI), P value] of PICU deaths of 7.5 (CI 3.1-18.1, P < 0.0001), 4.5 (CI 2.0-9.8, P < 0.0002) and 5.7 (CI 3.4-9.5, P < 0.0001), respectively. In SP, older children had significantly higher prevalence of premorbid conditions such as malignancy, mental retardation/cerebral palsy ± seizure disorders, chromosomal or genetic disorders (P = 0.003) than children <5 years of age. Serotypes were available for some of these specimens that included 19A, 6B, 3 and 6C. There were four SP deaths with multiorgan system failure and hemolytic uremic syndrome (two 19A and two serotype 3).

CONCLUSIONS

Severe streptococcal infections are associated with significant morbidity and mortality despite treatment with systemic antibiotics and intensive care unit support. GAS and SP affect the lungs of children, whereas GBS more likely causes meningitis in infants. The expanded coverage of newer polyvalent pneumococcal vaccines can probably prevent infections by serotypes 19A, 19F, 6B and 3.

High-dose amoxicillin with clavulanate for the treatment of acute otitis media in children

Objective. This study uses the acute otitis media clinical practice guideline proposed in 2004 as a reference to evaluate whether antibiotics doses that are in line with the recommendations lead to better prognosis. The study also attempts to clarify possible factors that influence the outcome. Study Design. Retrospective cohort study. Subjects and Methods. A total of 400 children with acute otitis media were enrolled. The dosage of amoxicillin was considered to be appropriate when in accord with clinical practice guidelines, that is, 80–90 mg/kg/day. The outcome was defined according to the description of tympanic membrane on medical records. Multivariate logistic regression was used to analyze the relationship between antibiotic dosage and prognosis after adjusting for baseline factors. Results. The majority of prescriptions were under dosage (89.1%) but it was not noticeably associated with outcome (P = 0.41). The correlation between under dosage and poor prognosis was significant in children below 20 kg with bilateral acute otitis media (odds ratio 1.63; 95% CI 1.02–2.59, P = 0.04). Conclusion. Treating acute otitis media in children, high-dose amoxicillin with clavulanate as recommended in the clinical practice guideline was superior to conventional doses only in children under 20 kg with bilateral diseases.

Current concepts in the treatment of bacterial meningitis beyond the neonatal period

The epidemiology and treatment approach to bacterial meningitis has changed dramatically since the advent of antimicrobial therapy. New vaccines against meningeal pathogens have been implemented into national immunization programs successfully around the world. Antibiotic resistance has had a considerable impact on the efficacy of several therapeutic agents. In this review, the authors will discuss the principles of antibiotic chemotherapy, focusing on new agents for the treatment of penicillin-resistant pneumococci and adjunctive treatments to reduce the inflammatory response to bacterial infection of the meninges.

Pneumococcal serotypes before and after introduction of conjugate vaccines, United States, 1999-2011(1.)

Serotyping data for pneumococci causing invasive and noninvasive disease in 2008-2009 and 2010-2011 from >43 US centers were compared with data from preconjugate vaccine (1999-2000) and postconjugate vaccine (2004-2005) periods. Prevalence of 7-valent pneumococcal conjugate vaccine serotypes decreased from 64% of invasive and 50% of noninvasive isolates in 1999-2000 to 3.8% and 4.2%, respectively, in 2010-2011. Increases in serotype 19A stopped after introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. Prevalences of other predominant serotypes included in or related to PCV13 (3, 6C, 7F) also remained similar for 2008-2009 and 2010-2011. The only major serotype that increased from 2008-2009 to 2010-2011 was nonvaccine serotype 35B. These data show that introduction of the 7-valent vaccine has dramatically decreased prevalence of its serotypes and that addition of serotypes in PCV13 could provide coverage of 39% of isolates that continue to cause disease.

Bacterial meningitis

Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained, preceding any imaging studies. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, and an altered level of consciousness but signs may be scarce in children, in the elderly, and in meningococcal disease. Host genetic factors are major determinants of susceptibility to meningococcal and pneumococcal disease. Dexamethasone therapy has been implemented as adjunctive treatment of adults with pneumococcal meningitis. Adequate and prompt treatment of bacterial meningitis is critical to outcome. In this chapter we review the epidemiology, pathophysiology, and management of bacterial meningitis.

From knock-out phenotype to three-dimensional structure of a promising antibiotic target from Streptococcus pneumoniae

Given the rise in drug-resistant Streptococcus pneumoniae, there is an urgent need to discover new antimicrobials targeting this pathogen and an equally urgent need to characterize new drug targets. A promising antibiotic target is dihydrodipicolinate synthase (DHDPS), which catalyzes the rate-limiting step in lysine biosynthesis. In this study, we firstly show by gene knock out studies that S. pneumoniae (sp) lacking the DHDPS gene is unable to grow unless supplemented with lysine-rich media. We subsequently set out to characterize the structure, function and stability of the enzyme drug target. Our studies show that sp-DHDPS is folded and active with a k(cat) = 22 s(-1), K(M)(PYR) = 2.55 ± 0.05 mM and K(M)(ASA) = 0.044 ± 0.003 mM. Thermal denaturation experiments demonstrate sp-DHDPS exhibits an apparent melting temperature (T(M)(app)) of 72 °C, which is significantly greater than Escherichia coli DHDPS (Ec-DHDPS) (T(M)(app) = 59 °C). Sedimentation studies show that sp-DHDPS exists in a dimer-tetramer equilibrium with a K(D)(4→2) = 1.7 nM, which is considerably tighter than its E. coli ortholog (K(D)(4→2) = 76 nM). To further characterize the structure of the enzyme and probe its enhanced stability, we solved the high resolution (1.9 Å) crystal structure of sp-DHDPS (PDB ID 3VFL). The enzyme is tetrameric in the crystal state, consistent with biophysical measurements in solution. Although the sp-DHDPS and Ec-DHDPS active sites are almost identical, the tetramerization interface of the s. pneumoniae enzyme is significantly different in composition and has greater buried surface area (800 Å(2)) compared to its E. coli counterpart (500 Å(2)). This larger interface area is consistent with our solution studies demonstrating that sp-DHDPS is considerably more thermally and thermodynamically stable than Ec-DHDPS. Our study describe for the first time the knock-out phenotype, solution properties, stability and crystal structure of DHDPS from S. pneumoniae, a promising antimicrobial target.

Procalcitonin versus C-reactive protein for guiding antibiotic therapy in sepsis: a randomized trial

OBJECTIVE

We sought to evaluate whether procalcitonin was superior to C-reactive protein in guiding antibiotic therapy in intensive care patients with sepsis.

DESIGN

Randomized open clinical trial.

SETTING

Two university hospitals in Brazil.

PATIENTS

Patients with severe sepsis or septic shock.

INTERVENTIONS

Patients were randomized in two groups: the procalcitonin group and the C-reactive protein group. Antibiotic therapy was discontinued following a protocol based on serum levels of these markers, according to the allocation group. The procalcitonin group was considered superior if the duration of antibiotic therapy was at least 25% shorter than in the C-reactive protein group. For both groups, at least seven full-days of antibiotic therapy were ensured in patients with Sequential Organ Failure Assessment greater than 10 and/or bacteremia at inclusion, and patients with evident resolution of the infectious process had antibiotics stopped after 7 days, despite biomarkers levels.

MEASUREMENTS AND MAIN RESULTS

Ninety-four patients were randomized: 49 patients to the procalcitonin group and 45 patients to the C-reactive protein group. The mean age was 59.8 (SD, 16.8) years. The median duration of antibiotic therapy for the first episode of infection was 7.0 (Q1-Q3, 6.0-8.5) days in the procalcitonin group and 6.0 (Q1-Q3, 5.0-7.0) days in the C-reactive protein group (p=0.13), with a hazard ratio of 1.206 (95% CI, 0.774-1.3; p=0.13). Overall, protocol overruling occurred in only 13 (13.8%) patients. Twenty-one patients died in each group (p=0.836).

CONCLUSIONS

C-reactive protein was as useful as procalcitonin in reducing antibiotic use in a predominantly medical population of septic patients, causing no apparent harm.

Virulence potential and genome-wide characterization of drug resistant Streptococcus pneumoniae clones selected in vivo by the 7-valent pneumococcal conjugate vaccine

We used mouse models of pneumococcal colonization and disease combined with full genome sequencing to characterize three major drug resistant clones of S. pneumoniae that were recovered from the nasopharynx of PCV7-immunized children in Portugal. The three clones--serotype 6A (ST2191), serotype 15A (ST63) and serotype 19A (ST276) carried some of the same drug resistance determinants already identified in nasopharyngeal isolates from the pre-PCV7 era. The three clones were able to colonize efficiently the mouse nasopharyngeal mucosa where populations of these pneumococci were retained for as long as 21 days. During this period, the three clones were able to asymptomatically invade the olfactory bulbs, brain, lungs and the middle ear mucosa and established populations in these tissues. The virulence potential of the three clones was poor even at high inoculum (10(5) CFU per mouse) concentrations in the mouse septicemia model and was undetectable in the pneumonia model. Capsular type 3 transformants of clones 6A and 19A prepared in the laboratory produced lethal infection at low cell concentration (10(3) CFU per mouse) but the same transformants became impaired in their potential to colonize, indicating the importance of the capsular polysaccharide in both disease and colonization. The three clones were compared to the genomes of 56 S. pneumoniae strains for which sequence information was available in the public databank. Clone 15A (ST63) only differed from the serotype 19F clone G54 in a very few genes including serotype so that this clone may be considered the product of a capsular switch. While no strain with comparable degree of similarity to clone 19A (ST276) was found among the sequenced isolates, by MLST this clone is a single locust variant (SLV) of Denmark14-ST230 international clone. Clone 6A (ST2191) was most similar to the penicillin resistant Hungarian serotype 19A clone.