The activity of levofloxacin and other antimicrobials against clinical isolates of Streptococcus pneumoniae collected worldwide during 1999-2002

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Serotype distribution and antibiotic resistance of 140 pneumococcal isolates from pediatric patients with upper respiratory infections in Beijing, 2010

In the present study, the serotype distribution and antibiotic resistance of S. pneumoniae from pediatric patients with upper respiratory infections in Beijing, 2010 were described. 140 pneumococcal isolates were obtained, and the prevailing five serotypes were 19F (18.6%), 23F (9.3%), 14 (9.3%), 15 (9.3%), and 6A (7.1%). The vaccine coverage of PCV7, PCV10, and PCV13 were 43.6%, 43.6%, and 60.0%, respectively. According to the CLSI 2010 criteria, 99.3% of the S. pneumoniae isolates were susceptible to penicillin. The resistance rates to erythromycin and azithromycin were 96.4% and 97.1%, respectively. Meanwhile, 64.3% (90/140) of all pneumococcal isolates were multidrug-resistant S. pneumoniae (MDRSP). PCV13 covered 68.9% (62/90) of MDRSP strains, whereas it was 47.8% (43/90) for PCV7. ErmB was the dominant macrolide-resistance gene, whereas 30.4% pneumococcal isolates expressed both ermB and mefA. No isolate expressed ermTR. The potential coverage of PCV13 is higher than PCV7 and PCV10 because high rates of serotypes 6A and 19A, and the conjugate vaccines could prevent the spread of MDRSP. S. pneumoniae is still sensitive to penicillin. The resistance rate of S. pneumoniae to macrolides is high and ermB is the dominant macrolide-resistance gene in China, so continued surveillance of the antimicrobial susceptibility of S. pneumoniae may be necessary.

Reporting Emerging Resistance of Streptococcus pneumoniae from India

Background:

There are reports of emergence of resistant strains of S. pneumoniae showing resistance to penicillin from all over the world, and now, resistance to multiple drugs (multidrug-resistant strains) has been added to it. However, scanty reports are available so far from India, depicting such resistance.

Aims:

The aim of the present study is to look for the prevalence of penicillin-resistant pneumococci and also the multidrug-resistant strains among S. pneumoniae, isolated from respiratory specimens, in the coastal part of South India.

Settings and Design:

A cross-sectional study was conducted from June 2008 to December 2008, in our tertiary care center. Fifty pathogenic clinical isolates were collected from patients suffering from lower respiratory tract infections.

Materials and Methods:

Penicillin resistance was screened by 1 μg oxacillin disk on Muller-Hinton blood agar followed by Minimum Inhibitory Concentration (MIC) detection by the agar dilution method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. Antibiotic susceptibility for other antibiotics was carried out by the Kirby Bauer disk diffusion method followed by an E-test with HiComb test strips from Hi-media.

Results:

Out of 50 isolates, 4% (95% Confidence Interval - 1.4, 9.4) showed total resistance to penicillin, whereas, 10% (95% CI; 1.6, 18.3) showed intermediate resistance. These penicillin-resistant pneumococci (4%) were also found to be multidrug-resistant (MDR) strains. Maximum resistance was observed for cotrimoxazole and tetracycline (24% each with 95% CI; 12.2, 35.8) followed by erythromycin and ciprofloxacin (14% each with 95%CI; 4.4, 23.6).

Conclusions:

Increasing emergence of the resistant strains of S. pneumoniae in the community set up requires continuous monitoring and a restricted use of antibiotics to keep a check on its resistance pattern, for an effective treatment plan.

In vitro and in vivo profiles of ACH-702, an isothiazoloquinolone, against bacterial pathogens

ACH-702, a novel isothiazoloquinolone (ITQ), was assessed for antibacterial activity against a panel of Gram-positive and Gram-negative clinical isolates and found to possess broad-spectrum activity, especially against antibiotic-resistant Gram-positive strains, including methicillin-resistant Staphylococcus aureus (MRSA). For Gram-negative bacteria, ACH-702 showed exceptional potency against Haemophilus influenzae, Moraxella catarrhalis, and a Neisseria sp. but was less active against members of the Enterobacteriaceae. Good antibacterial activity was also evident against several anaerobes as well as Legionella pneumophila and Mycoplasma pneumoniae. Excellent bactericidal activity was observed for ACH-702 against several bacterial pathogens in time-kill assays, and postantibiotic effects (PAEs) of >1 h were evident with both laboratory and clinical strains of staphylococci at 10 × MIC and similar in most cases to those observed for moxifloxacin at the same MIC multiple. In vivo efficacy was demonstrated against S. aureus with murine sepsis and thigh infection models, with decreases in the number of CFU/thigh equal to or greater than those observed after vancomycin treatment. Macromolecular synthesis assays showed specific dose-dependent inhibition of DNA replication in staphylococci, and biochemical analyses indicated potent dual inhibition of two essential DNA replication enzymes: DNA gyrase and topoisomerase IV. Additional biological data in support of an effective dual targeting mechanism of action include the following: low MIC values (≤0.25 μg/ml) against staphylococcal strains with single mutations in both gyrA and grlA (parC), retention of good antibacterial activity (MICs of ≤0.5 μg/ml) against staphylococcal strains with two mutations in both gyrA and grlA, and low frequencies for the selection of higher-level resistance (<10⁻¹⁰). These promising initial data support further study of isothiazoloquinolones as potential clinical candidates.

Design and synthesis of anti-MRSA benzimidazolylbenzene-sulfonamides. QSAR studies for prediction of antibacterial activity

A series of benzimidazolylbenzenesulfonamide compounds containing electron-releasing and electron-withdrawing substituents were synthesized and tested for their in vitro antibacterial activity. Two BZS compounds showed strong antibacterial activity against methicillin-resistant Staphylococcus aureus and Bacillus subtilis. Quantitative studies of their structure-activity relationship using a simple linear regression analysis were applied to explore the correlation between the biological activity and the charges on acidic hydrogen atoms in the synthesized compounds.

Economic evaluation of universal infant vaccination with 7vPCV in Hong Kong

OBJECTIVES

The purpose of this study was to evaluate the clinical and economic benefits of routine infant vaccination with seven-valent pneumococcal conjugate vaccine (7vPCV) in Hong Kong.

METHODS

A decision-analytic model was populated with local age-specific incidence data to simulate the expected health outcomes resulting from 7vPCV vaccination of a birth cohort of 57,100 children compared with an unvaccinated cohort over a 10-year horizon. Primary analyses were conducted from a payer perspective, using local inpatient and outpatient costs associated with the treatment of pneumococcal disease. Vaccine efficacy rates were consistent with results from pivotal clinical trials. The reduction in adult invasive pneumococcal disease (IPD) and associated cost avoidance due to the indirect effect of vaccination were estimated in line with published overseas rates.

RESULTS

Universal 7vPCV vaccination was estimated to prevent 524 cases of IPD and more than 2580 cases of otitis media in the birth cohort over a 10-year period, leading to a reduction of HK$28.7 million (US$3.7 million) in direct medical costs. Additional cost savings from the indirect prevention of 919 adult cases of IPD during this time period also resulted. Overall, 7vPCV vaccination was estimated to have an incremental cost per life-year gained of HK$50,456 (US$6460) from a payer perspective or HK$46,308 (US$5929) when both direct and indirect costs were included.

CONCLUSION

With reference to the World Health Organization's threshold for cost-effectiveness, results from this study indicate that routine infant vaccination with 7vPCV is a cost-effective intervention because of the added cost savings resulting from the indirect effect of vaccination on adult disease.

Otitis Media: A Review, with a Focus on Alternative Treatments

Otitis media (OM) is the accumulation of fluids in the middle ear, with or without symptoms of inflammation. The infection is caused by dysfunction or obstruction of the eustachian tube and is most commonly diagnosed in children under the age of two. The microbiology of OM differs, with Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis the most commonly isolated pathogens. The emergence of penicillin-resistant Strep. pneumoniae, β-lactamase-producing strains, Haem. influenzae and Mor. catarrhalis is a major concern and health care costs associated with treatment are substantial, especially in cases of unresponsive treatment as a result of incorrect diagnosis. Alternative treatments such as vaccines and a nasal spray containing α-haemolytic streptococci with antimicrobial activity against OM pathogens, have been developed. The rationale behind such treatments is to induce an appropriate immune response against the pathogens and decrease bacterial colonisation in the nasopharynx. Another approach may be treatment with bacteriocins (natural antimicrobial peptides) or bacteriocin-like inhibitory substances (BLIS) produced by lactic acid bacteria. We have recently described an antibacterial peptide produced by Enterococcus mundtii ST4SA and have published on bacteriocins (enterocins) with antibacterial and antiviral activity. This review discusses the condition OM, summarises current methods used to treat the infection, and suggests alternative safe and natural treatments that need to be explored.

In vitro activities of the Rx-01 oxazolidinones against hospital and community pathogens

Rx-01_423 and Rx-01_667 are two members of the family of oxazolidinones that were designed using a combination of computational and medicinal chemistry and conventional biological techniques. The compounds have a two- to eightfold-improved potency over linezolid against serious gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant streptococci, and vancomycin-resistant enterococci. This enhanced potency extends to the coverage of linezolid-resistant gram-positive microbes, especially multidrug-resistant enterococci and pneumococci. Compounds from this series expand the spectrum compared with linezolid to include fastidious gram-negative organisms like Haemophilus influenzae and Moraxella catarrhalis. Like linezolid, the Rx-01 compounds are bacteriostatic against MRSA and enterococci but are generally bactericidal against S. pneumoniae and H. influenzae.

Regional trends in β-lactam, macrolide, fluoroquinolone and telithromycin resistance among Streptococcus pneumoniae isolates 2001–2004

OBJECTIVES

To determine global antibacterial resistance rates among community-acquired isolates of Streptococcus pneumoniae.

METHODS

Between 2001 and 2004, 20,142 S. pneumoniae isolates from 151 centres in 40 countries were collected and tested for susceptibility to common antibacterials in the PROTEKT surveillance study.

RESULTS

The prevalence of beta-lactam and macrolide resistance did not change, but there was marked geographic variability. The most common macrolide resistance mechanism was ribosomal methylation mediated by erm(B), except in Canada, Greece and the USA where drug efflux mediated by mef(A) was predominant. The erythromycin minimum inhibitory concentration for mef(A) isolates increased significantly (P<0.001; chi2 test). The global prevalence of macrolide-resistant isolates positive for both erm(B) and mef(A) was 12.0% in 2003-2004; erm(B)+mef(A) strains were particularly common in South Korea (40.8%), South Africa (46.4%) and the USA (29.6%). Telithromycin was the most active antibacterial tested. Over the studied period, > or = 99.7% of all isolates and > 99% of erythromycin-resistant isolates, irrespective of genotype, were susceptible to telithromycin.

CONCLUSIONS

These results confirm the high worldwide prevalence of resistance to commonly used antibacterial agents and multiple resistance phenotypes among clinical isolates of S. pneumoniae and suggest that high-level macrolide resistance is continuing to increase in most countries.

Pharmacodynamics of simulated total versus free-drug serum concentrations of a low versus a high protein bound third-generation oral cephalosporin (Cefpodoxime versus cefditoren) against Streptococcus pneumoniae

Pharmacodynamic parameters and bactericidal activity against Streptococcus pneumoniae were investigated by simulating total and free serum concentrations of cefpodoxime versus cefditoren. Total drug T>MIC against the penicillin-intermediate (PISP) and resistant (PRSP) strains were 70.6% and 42.9% for cefpodoxime, and 89.6% and 62.5% for cefditoren, respectively. Comparing activity of free versus total cefpodoxime, there were reductions of 8.5% and 19.1% in T>MIC, related to bactericidal activity reductions from approximately 4.5 to 3 log(10), and from 3 to 2.5 log(10 )against PISP and PRSP, respectively, at 10-12h. For cefditoren, reductions of 45.4% and 100% in T>MIC, were related to bactericidal activity reductions from approximately 5.5 to 2-2.5 log(10 )and from approximately 2.5 to 1.5 log(10 )against PISP and PRSP, respectively, at 10-12h. Higher differences in activity were found against the less resistant strains when comparing total versus free-drug profile.

In vitro and in vivo antibacterial activities of heteroaryl isothiazolones against resistant gram-positive pathogens

The activities of several tricyclic heteroaryl isothiazolones (HITZs) against an assortment of gram-positive and gram-negative clinical isolates were assessed. These compounds target bacterial DNA replication and were found to possess broad-spectrum activities especially against gram-positive strains, including antibiotic-resistant staphylococci and streptococci. These included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-nonsusceptible staphylococci, and quinolone-resistant strains. The HITZs were more active than the comparator antimicrobials in most cases. For gram-negative bacteria, the tested compounds were less active against members of the family Enterobacteriaceae but showed exceptional potencies against Haemophilus influenzae, Moraxella catarrhalis, and Neisseria spp. Good activity against several anaerobes, as well as Legionella pneumophila and Mycoplasma pneumoniae, was also observed. Excellent bactericidal activity against staphylococci was observed in time-kill assays, with an approximately 3-log drop in the numbers of CFU/ml occurring after 4 h of exposure to compound. Postantibiotic effects (PAEs) of 2.0 and 1.7 h for methicillin-susceptible S. aureus and MRSA strains, respectively, were observed, and these were similar to those seen with moxifloxacin at 10x MIC. In vivo efficacy was demonstrated in murine infections by using sepsis and thigh infection models. The 50% protective doses were <or=1 mg/kg of body weight against S. aureus in the sepsis model, while decreases in the numbers of CFU per thigh equal to or greater than those detected in animals treated with a standard dose of vancomycin were seen in the animals with thigh infections. Pharmacokinetic analyses of treated mice indicated exposures similar to those to ciprofloxacin at equivalent dose levels. These promising initial data suggest further study on the use of the HITZs as antibacterial agents.

Oropharyngeal colonization by Streptococcus pneumoniae among HIV-infected adults in Uganda: assessing prevalence and antimicrobial susceptibility

OBJECTIVES

To evaluate characteristics of Streptococcus pneumoniae associated with oropharyngeal colonization in the Ugandan adult HIV population.

METHODS

We conducted a cross-sectional study at the outpatient HIV clinic at the Joint Clinical Research Centre in Kampala, Uganda between July 2004 and February 2005. Six hundred HIV-infected individuals were interviewed and had oropharyngeal specimens collected. Pneumococci were isolated from these specimens and antimicrobial susceptibility patterns determined using standard microdilution methods. Serotypes of the pneumococcal isolates were evaluated by capsular swelling reaction with commercial antisera.

RESULTS

The prevalence of oropharyngeal colonization with pneumococci was 18% (108/600). Thirty-two different pneumococcal serotypes were identified, and the most common were serotypes 3 (14.7%), 19F (6.4%), 23F (6.4%), and 16 (5.5%). Seventy-two percent of the isolates were penicillin (PCN) intermediate (MICs 0.12-1 microg/mL), the remainder all being PCN susceptible, and >99% were trimethoprim-sulfamethoxazole (TMP-SMX) resistant. Novel PCN intermediate serotypes included 7, 11, 16, 20, 22, 24, and 34. Only one isolate was resistant to macrolides, and resistance to other antibiotics was rare.

CONCLUSIONS

HIV-infected adults in Uganda are colonized with pneumococci that exhibit a high degree of TMP-SMX and PCN non-susceptibility, with several unique PCN non-susceptible serotypes that are not included in current vaccine preparations.

Intrapulmonary pharmacokinetics and pharmacodynamics of high-dose levofloxacin in healthy volunteer subjects

The objective of this study was to determine the plasma and intrapulmonary pharmacokinetic parameters of intravenously administered levofloxacin in healthy volunteers. Three doses of either 750 mg or 1000 mg levofloxacin were administered intravenously to 4 healthy adult subjects (750 mg) to 20 healthy adult subjects divided into five groups of 4 subjects (1000 mg). Standardised bronchoscopy and timed bronchoalveolar lavage (BAL) were performed following administration of the last dose. Blood was obtained for drug assay prior to drug administration and at the time of BAL. Levofloxacin was measured in plasma, BAL fluid and alveolar cells (ACs) using a sensitive and specific combined high-performance liquid chromatographic tandem mass spectrometric technique (HPLC/MS/MS). Plasma, epithelial lining fluid (ELF) and AC pharmacokinetics were derived using non-compartmental methods. The maximum plasma drug concentration to minimum inhibitory concentration ratio (C(max)/MIC(90)) and the area under the drug concentration curve to minimum inhibitory concentration ratio (AUC/MIC(90)) during the dosing interval were calculated for potential respiratory pathogens with MIC(90) values from 0.03 microg/mL to 2 microg/mL. In the 1000 mg dose group, the C(max) (mean+/-standard deviation (S.D.)), AUC(0-8h) and half-life were: for plasma, 9.2+/-1.9 microg/mL, 103.6 microg h/mL and 7.45 h; for ELF, 25.8+/-7.9 microg/mL, 279.1 microg h/mL and 8.10h; and for ACs, 51.8+/-26.2 microg/mL, 507.5 microg h/mL and 14.32 h. In the 750 mg dose group, the C(max) values in plasma, ELF and ACs were 5.7+/-0.4, 28.0+/-23.6 and 34.2+/-18.7 microg/mL, respectively. Levofloxacin concentrations were significantly higher in ELF and ACs than in plasma at all time points. For pathogens commonly associated with community-acquired pneumonia, C(max)/MIC(90) ratios in ELF ranged from 12.9 for Mycoplasma pneumoniae to 859 for Haemophilus influenzae, and AUC/MIC(90) ratios ranged from 139 to 9303, respectively. The C(max)/MIC(90) ratios in ACs ranged from 25.9 for M. pneumoniae to 1727 for H. influenzae, and AUC/MIC(90) ratios ranged from 254 to 16917, respectively. The C(max)/MIC(90) and AUC/MIC(90) ratios provide a pharmacokinetic rationale for once-daily administration of a 1000 mg dose of levofloxacin and are favourable for the treatment of community-acquired respiratory pathogens.

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

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

In vitro antibacterial activity of DX-619, a novel des-fluoro(6) quinolone

The in vitro activities of DX-619, des-fluoro(6) quinolone, against 1,208 clinical isolates were examined. DX-619 was particularly potent against staphylococci, including ciprofloxacin- and methicillin-resistant strains; the MIC at which 90% of the strains tested were inhibited was 0.5 microg/ml. In addition, DX-619 was also active against gram-negative bacteria.

Evolving Concepts of Pharmaceutical Company–Sponsored Surveillance Studies

As a result of increasing bacterial resistance to antimicrobial agents, there is a need to conduct studies that monitor changes in susceptibility. In addition to studying the emergence and dissemination of antibacterial resistance, pharmaceutical companies perform surveillance studies for a number of reasons. As an example, the Alexander Project was conducted to study community-acquired respiratory infections internationally over 10 years. The project's findings have been valuable in the study of antimicrobial resistance. The Alexander Project has also been instrumental in the study of the evolution of resistance genes and in predictions of future rates of resistance, as well as in establishing the importance of high-quality data, the complexity of the evolution of resistance, and the need to disseminate the results in a variety of formats. Although there has been a reduction in pharmaceutical company studies, consolidated efforts between industry, government, and private groups have increased. Future surveillance efforts by pharmaceutical companies will likely be more targeted and disease directed.

Addition of macrolide in treating adult hospitalized community-acquired pneumonia

OBJECTIVES

Current clinical practice guidelines, including those in south Asia, recommend the addition of a macrolide to a broad-spectrum antibiotic for the treatment of severe hospitalized community-acquired pneumonia (CAP). The aim of this study was to observe the influence of macrolide addition on clinical outcomes of hospitalized adult patients with CAP.

METHODOLOGY

Over a 16-month period between 2002 and 2004, 141 eligible patients were prospectively recruited from an urban-based teaching hospital in Malaysia.

RESULTS

Of the 141 patients, 63 (44.7%) patients (age (standard deviation (SD)) 56 (20.0) years; 50.8% male) received a macrolide-containing antibiotic regimen, while 78 (55.3%; age (SD) 57 (20.2) years; 52.6% male) were on a single broad-spectrum antibiotic only. In total, 39 (27.7%) and 102 (72.3%) patients had severe and 'non-severe' pneumonia, respectively. Irrespective of whether they had severe or non-severe pneumonia, there were no significant differences in mortality (non-severe pneumonia, 6.5% vs. 5.4%, P = 0.804; severe pneumonia, 17.6% vs. 18.2%, P = 0.966), need of ventilation (non-severe pneumonia, 8.7% vs. 3.6%, P = 0.274; severe pneumonia, 23.5% vs. 13.6%, P = 0.425) or median length of hospital stay (non-severe pneumonia, 5.5 vs. 5 days, P = 0.954; severe pneumonia, 7 vs. 6 days, P = 0.401) between the two treatment regimens.

CONCLUSION

This observational, non-randomized study suggests that addition of a macrolide may not convey any extra clinical benefits in adult hospitalized patients with CAP.

A review of Streptococcus pneumoniae infection treatment failures associated with fluoroquinolone resistance

We reviewed all of the published reports of cases of fluoroquinolone treatment failures for respiratory tract infection due to fluoroquinolone-resistant Streptococcus pneumoniae. There were 20 ciprofloxacin and levofloxacin treatment failures reported. Physicians should be aware, when treating pneumococcal respiratory tract infections in older patients with a fluoroquinolone, that clinical failures might occur, especially for patients with comorbid illnesses and a history of recent fluoroquinolone use.

Role of efflux mechanisms on fluoroquinolone resistance in Streptococcus pneumoniae and Pseudomonas aeruginosa

Prokaryotic efflux mechanisms can effectively increase the intrinsic resistance of bacteria by actively transporting antibiotics out of cells, thus reducing the effective concentration of these agents. The fluoroquinolones, similar to most other antimicrobial classes, are susceptible to efflux mechanisms, particularly in Gram-negative organisms, such as Pseudomonas aeruginosa. Resistant P. aeruginosa clones isolated after fluoroquinolone therapy frequently over express at least one of the multiple efflux pump mechanisms found in this organism. Gram-positive bacteria, such as Streptococcus pneumoniae, also possess efflux mechanisms, though their effect on fluoroquinolone resistance seems to be more limited and selective. In the future, efflux pump inhibitors may offer effective adjunctive therapy to antibiotics for the treatment of difficult infections by efflux mutants. In the meantime, appropriate antibiotic selection and optimal dosing strategies should aim to eradicate the causative pathogen before a resistant efflux mutant can emerge.

Comparative activity of oral and parenteral cephalosporins tested against multidrug-resistant Streptococcus pneumoniae: report from the SENTRY Antimicrobial Surveillance Program (1997–2003)

A large international collection of Streptococcus pneumoniae (21605 strains) was analyzed to determine the comparative activity of selected oral (cefuroxime and cefpodoxime) and parenteral (ceftriaxone and cefepime) cephalosporins when tested against different antimicrobial resistance phenotypes including penicillin-resistant strains and strains displaying additional resistances to other agents (erythromycin, clindamycin, tetracycline, and trimethoprim/sulfamethoxazole). The multidrug-resistant (MDR) rate ranged from 17.6% (penicillin- and erythromycin-resistant only) to 5.7% (resistance to all 5 drugs). The parenteral cephalosporins retained wider activity for all MDR phenotypes studied with the resistance rates (minimum inhibitory concentration > or = 4 mug/mL) being lower for cefepime (1.3-1.9%) when compared with ceftriaxone (3.0-4.4%) or the orally administered cephalosporins, cefpodoxime (64.4-74.1%), and cefuroxime (69.3-79.1%). Our findings confirm that the parenteral cephalosporins, cefepime, and ceftriaxone possess significant activity against those MDR pneumococci responsible for an increasing number of serious respiratory tract infections.