Risk factors and clinical significance of invasive infections caused by levofloxacin-resistant Streptococcus pneumoniae

Nationwide surveillance of antimicrobial resistance in invasive isolates of Streptococcus pneumoniae in Taiwan from 2017 to 2019

BACKGROUND/PURPOSE

Streptococcus pneumoniae causes pneumonia and other invasive diseases, and is a leading cause of mortality in the elderly population. The present study aimed to provide current antimicrobial resistance and epidemiological profiles of S. pneumoniae infections in Taiwan.

METHODS

A total of 252 nonduplicate S. pneumoniae isolates were collected from patients admitted to 16 hospitals in Taiwan between January 2017 and December 2019, and were analyzed. The minimum inhibitory concentration of antibiotics was determined using the Vitek 2 automated system for antimicrobial susceptibility testing. Furthermore, epidemiological profiles of S. pneumoniae infections were analyzed.

RESULTS

Among the strains analyzed, 88% were recognized as invasive pneumococcal strains. According to the Clinical and Laboratory Standards Institute criteria for non-meningitis, the prevalence of penicillin-non-susceptible S. pneumoniae demonstrated a declining trend from 43.6% in 2017 to 17.2% in 2019. However, the rate of penicillin-non-susceptible S. pneumoniae was 85.7% based on the criteria for meningitis. Furthermore, the prevalence of ceftriaxone-non-susceptible S. pneumoniae was 62.7% based on the criteria for meningitis. Isolates demonstrated higher susceptibility toward doripenem and ertapenem than toward meropenem and imipenem. An increased rate of non-susceptibility toward levofloxacin was observed in southern Taiwan (15.1%) and elderly patients (≥65 years; 11.4%). Most isolates were susceptible to vancomycin and linezolid.

CONCLUSION

Empirical treatment with ceftriaxone monotherapy for pneumococcal meningitis should be carefully monitored owing to its high non-susceptibility rate. The susceptibility rates of most isolates to penicillin (used for treating non-meningitis pneumococcal diseases), carbapenems (ertapenem and doripenem), respiratory quinolones (moxifloxacin and levofloxacin), vancomycin, and linezolid suggested the potential of these antibiotics in treating pneumococcal diseases in Taiwan.

Pharmacokinetic/pharmacodynamic evaluation of the antimicrobial therapy of pneumococcal invasive disease in adults in post-PCV13 vaccine period in Madrid, Spain

The objective of our study was to evaluate by pharmacokinetic/pharmacodynamic (PK/PD) analysis, if the antimicrobials used for the treatment of invasive pneumococcal disease (IPD) in adults, including meningitis, are adequate considering the susceptibility profile of S. pneumoniae in Spain after the implantation of PVC13 vaccine. Pharmacokinetic parameters of benzylpenicillin and cefotaxime were obtained from the literature, and susceptibility data of invasive S. pneumoniae strains recovered in 2017 (post-PCV13 vaccination period) were provided by the Public Health Regional Laboratory of Madrid. We have also studied levofloxacin because it is used to treat pneumococcal pneumonia previously to be diagnosed as bacteremic pneumonia. Monte Carlo simulation was used to estimate the probability of target attainment (PTA) and the cumulative fraction of response (CFR). All doses of benzylpenicillin except 2 mU q6h provide a high probability of treatment success for MIC values ≤ 1 mg/L; 4 mU q4h is even useful for MIC values up to 4 mg/L. This high dose, used for the treatment of meningitis, also provides high probability of treatment success for MIC ≤ 0.5 mg/L. At the susceptibility EUCAST breakpoint (≤ 0.5 mg/L), cefotaxime provides a high rate of PD target achievement, even at the lowest dose (1 g q8h). For meningitis, 2 g q6h ensures probabilities of target attainment ≥90% for MIC up to 1 mg/L. Our study confirms that after the implementation of PCV13 vaccine, the treatment with benzylpenicillin and cefotaxime provides high probability of the therapy success of IPD, including meningitis.

Antibiotic Resistance Is Associated with Integrative and Conjugative Elements and Genomic Islands in Naturally Circulating Streptococcus pneumoniae Isolates from Adults in Liverpool, UK

Pneumonia is the sixth largest cause of death in the UK. It is usually caused by Streptococcus pneumoniae, which healthy individuals can carry in their nose without symptoms of disease. Antimicrobial resistance further increases mortality and morbidity associated with pneumococcal infection, although few studies have analysed resistance in naturally circulating pneumococcal isolates in adult populations. Here, we report on the resistome and associated mobile genetic elements within circulating pneumococcus isolated from adult volunteers enrolled in the experimental human pneumococcal colonisation (EHPC) research program at the Liverpool School of Tropical Medicine, UK. Pneumococcal isolates collected from 30 healthy asymptomatic adults who had volunteered to take part in clinical research were screened for antibiotic susceptibility to erythromycin and tetracycline, and whole-genome sequenced. The genetic context of resistance to one or both antibiotics in four isolates was characterised bioinformatically, and any association of the resistance genes with mobile genetic elements was determined. Tetracycline and macrolide resistance genes [tet(M), erm(B), mef(A), msr(D)] were detected on known Tn916-like integrative and conjugative elements, namely Tn6002 and Tn2010, and tet(32) was found for the first time in S. pneumoniae located on a novel 50 kb genomic island. The widespread use of pneumococcal conjugate vaccines impacts on serotype prevalence and transmission within the community. It is therefore important to continue to monitor antimicrobial resistance (AMR) genes present in both vaccine types and non-vaccine types in response to contemporary antimicrobial therapies and characterise the genetic context of acquired resistance genes to continually optimise antibiotic therapies.

Risk Factors for Community-Onset Pneumonia Caused by Levofloxacin-Nonsusceptible Streptococcus pneumoniae

BACKGROUND

Fluoroquinolones are antibiotics commonly used in the treatment of infections caused by Streptococcus pneumoniae. However, rates of fluoroquinolone resistance are increasing with their frequent use. We designed this study to verify current fluoroquinolone resistance rates and risk factors for community-onset pneumococcal pneumonia.

METHODS

A retrospective case-control study was conducted in a tertiary referral hospital. The study population comprised patients admitted for pneumococcal pneumonia between January 2011 and May 2017. The case group included community-onset pneumonia caused by levofloxacin-nonsusceptible S. pneumoniae. The control group consisted of two patients with levofloxacin-susceptible S. pneumoniae who were admitted around the same time as each case.

RESULTS

A total of 198 pneumococcal pneumonia cases were identified during the study period. Twenty-five levofloxacin-resistant S. pneumoniae cases and 3 levofloxacin-intermediate S. pneumoniae cases were included in the case group (nonsusceptibility rate = 14.1%). Multivariate analysis showed that healthcare-associated factors (odds ratio [OR] 4.78, 95% confidence interval [CI] 1.39-16.43, p = 0.013), bronchopulmonary disease (OR 3.79, 95% CI 1.07-13.40, p = 0.039), cerebrovascular disease (OR 6.08, 95% CI 1.24-29.75, p = 0.026), and exposure to fluoroquinolones within the previous 3 months (OR 5.89, 95% CI 1.21-28.68, p = 0.028) were associated with nonsusceptibility to levofloxacin.

CONCLUSION

Independent risk factors for levofloxacin-nonsusceptible pneumococcal pneumonia were recent hospitalization, bronchopulmonary disease, cerebrovascular disease, and prior antibiotic use within 3 months. Careful selection of empirical antibiotics is thus needed in at-risk patients. Similarly, efforts to prevent the interpersonal spread of drug-resistant pathogens in long-term care facilities and to restrict unnecessary fluoroquinolone prescriptions are important.

Antimicrobial Resistance Among Streptococcus pneumoniae

Antibiotic resistance in Streptococcus pneumoniae (pneumococcus), the main pathogen responsible for community-acquired pneumonia (CAP), meningitis, bacteremia, and otitis media, is a major concern for clinicians. This pathogen is associated with high rates of morbidity and mortality, especially among children under 2 years old, immunocompromised persons, and the elderly population. The major anti-pneumococcus agents are β-lactams and macrolides, with fluoroquinolones ranking third. The emergence of antibiotic-resistant pneumococcus due to overuse of antibiotics is a global concern. While the discovery of novel classes of antibiotics for the pneumococcus is at a standstill, significant progress in reducing the problem of resistance is associated with antibacterial vaccines. Nevertheless, the World Health Organization recently considered drug-resistant S. pneumoniae as ranking among the 12 bacteria, for which there is an urgent need for new treatments. A challenge is to slow the evolution of new strains that are resistant to the vaccines.

Linezolid activity against clinical Gram-positive cocci with advanced antimicrobial drug resistance in Iran

OBJECTIVES

The aim of the study was to investigate the linezolid activity against clinical Gram-positive cocci with advanced antimicrobial drug resistance.

METHODS

A collection of methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococci (VRE), penicillin non-susceptible Streptococcus pneumoniae (PNSP), and group B streptococci (GBS) were isolated from various clinical samples. Antimicrobial susceptibility tests were done using standard methods Subsequently, we investigated linezolid antibacterial activities, the first approved oxazolidinone against isolates by the standard broth microdilution method.

RESULTS

According to our results, MRSA and PNSP isolates were multidrug resistant, and almost half of the VRE isolates were high level gentamicin resistant (HLGR). Furthermore, resistance to linezolid was not seen among the isolates. The MIC₉₀ values for MRSA, VRE, PNSP and GBS isolates were 4μg/ml, 2μg/ml, 1μg/ml, and 0.5μg/ml, respectively. Only 6.25% of vancomycin resistant enterococci showed intermediate susceptibility to this antibiotic.

CONCLUSIONS

These findings indicate that linezolid has an excellent activity against clinical drug resistant Gram-positive isolates in Iran. Constant monitoring and surveillance of linezolid MIC distribution allows the researchers to assess and detect gradual upward MIC drifts.

Prevalence of pneumococcal serotypes in adults ≥50 years of age

CONTEXT

Currently, majority of studies on antibiotic resistance and serotype prevalence in Streptococcus pneumoniae are in paediatric population and there is limited epidemiologic data pertaining to elderly Indian population.

AIMS

This study was undertaken to assess antibiotic resistance pattern and the coverage of the polysaccharide vaccine 23 (PPV23) in the elderly population.

SETTINGS AND DESIGN

This was a prospective 2-year pneumococcal surveillance study in patients with community-acquired pneumococcal infections of ≥50 years' age group on fifty isolates of S. pneumoniae.

MATERIALS AND METHODS

Antibiotic susceptibility by Kirby-Bauer disc diffusion method and minimum inhibitory concentration susceptibility testing by E-test method were performed for various antibiotics. All isolates were serotyped by the capsular Quellung method with commercial antisera.

RESULTS

All S. pneumoniae isolates were sensitive to penicillin and ceftriaxone. Non-susceptibility to levofloxacin, co-trimoxazole, erythromycin and clindamycin was noted as 16%, 74%, 10% and 6%, respectively. Prevalence of multidrug resistance in S. pneumoniae was observed as 6%. The most common serotypes observed in our study were 19A (14%), 8 (10%), 19F (8%), 3 (6%) and 9N (6%). PCV7, PCV10, PCV13 and PCV23 coverage was observed as 16%, 24%, 48% and 66%, respectively. The non-vaccine serotypes (NVTs) comprised 30% (n = 15) of the isolates.

CONCLUSIONS

Our study shows different antibiotic susceptibility patterns of S. pneumoniae as compared to other neighbouring regions in Asia. The modest coverage of S. pneumoniae serotypes by PPV23 vaccine and prevalence of diverse NVTs in adult population make it a challenging task to recommend further changes in the future vaccine.

Clinical and economic burden of community-acquired pneumonia in the Veterans Health Administration, 2011: a retrospective cohort study

Purpose

The burden of community-acquired pneumonia (CAP) is not well described in the US Veterans Health Administration (VHA).

Methods

CAP was defined as having a pneumonia diagnosis with evidence of chest X-ray, and no evidence of prior (90 days) hospitalization/long-term care. We calculated incidence rates of adult CAP occurring in inpatient or outpatient VHA settings in 2011. We also estimated the proportion of VHA CAP patients who were hospitalized, were readmitted within 30 days of hospital discharge, and died (any cause) in the year following diagnosis. Incremental costs during the 90 days following a CAP diagnosis were estimated from the perspective of the VHA.

Results

In 2011, 34,101 Veterans developed CAP (35,380 episodes) over 7,739,757 VHA person-years. Median age of CAP patients was 65 years (95 % male). CAP incidence rates were higher for those aged ≥50 years. A majority of Veterans aged 50–64 (53 %) and ≥65 (66 %) years had ≥1 chronic medical (moderate risk) or immunocompromising (high risk) condition. Compared to those at low-risk (healthy), moderate- and high-risk Veterans were >3 and >6 times more likely to develop CAP, respectively. The percentage of CAP patients who were hospitalized was 45 %, ranging from 12 % (age 18–49, low risk) to 57 % (age ≥65, high risk). One-year all-cause mortality rates ranged from 1 % (age 18–49, low risk) to 36 % (age ≥65, high risk). Annual VHA medical expenditure related to CAP was estimated to be $750 million (M) ($415M for those aged ≥65 years).

Conclusion

A focus on CAP prevention among older Veterans and those with comorbid or immunocompromising conditions is important.

Electronic supplementary material

The online version of this article (doi:10.1007/s15010-015-0789-3) contains supplementary material, which is available to authorized users.

Recurrent pneumococcal invasive disease in the region of Madrid during a five-year period

PURPOSE

The aim of this study was to describe the clinical and microbiological characteristics of recurrent invasive pneumococcal disease (RIPD) cases identified in the Region of Madrid between January 2007 and December 2011.

METHODS

Streptococcus pneumoniae serotyping was performed by Pneumotest-Latex and Quellung reaction. Molecular typing was carried out by pulsed-field gel electrophoresis (PFGE). A relapse was defined as any case of RIPD caused by strains with similar PFGE profile. Re-infections were defined by detection of recurrent episodes caused by strains with different PFGE patterns.

RESULTS

During the study period, 2,929 S. pneumoniae strains isolated from 2,858 patients with invasive pneumococcal disease (IPD) were studied. In 61 patients (2.1 %), 132 episodes of RIPD were detected (two episodes in 52 patients, three in 8 and four in 1). Twelve patients had relapses, 47 had re-infections and two had re-infections followed by relapses. Common risk factors to developing RIPD were HIV (42.6 %) and haematological malignancies (16.4 %). The most frequent serotypes were 8 (16 episodes) and 19A (15 episodes). Fourteen strains that were resistant to levofloxacin were also resistant to erythromycin. The proportion of strains co-resistant to erythromycin and levofloxacin was significantly higher in relapses (11/29) than in re-infections (3/103).

CONCLUSIONS

The occurrence of repeated episodes of IPD in the same patient over the time is not an exceptional issue. Some underlying conditions that may favour these recurrences, mainly immunosuppression, need to be considered in patients having an episode of IPD.