Evolution of antibiotic susceptibility profiles of staphylococci from osteoarticular infections: A 10-year retrospective study

BACKGROUND

Knowledge of the antibiotic susceptibility profiles of the bacteria responsible for osteoarticular infections is crucial for choosing the appropriate empirical antibiotic regimen. Wide use of broad spectrum antibiotics in these infections may have lead to selection of resistant bacteria. The aim of our study was to answer to these questions: (1) Did the bacterial pathogens isolated from osteoarticular infections (OAIs) and their antibiotic susceptibility profile change over the 10-year period in our University Hospital, particularly for Staphylococcus aureus and Coagulase negative staphylococci? (2) Are the antibiotics used for post-operative antibiotic therapy still effective against staphylococci involved in OAIs? (3) Are the antibiotics used for documented therapy still effective against staphylococci involved in OAIs?

HYPOTHESIS

We hypothetise that bacterial epidemiology and antibiotic resistance rates have changed little thanks to a reasoned prescription of antibiotics in our Center.

MATERIALS AND METHODS

We performed a retrospective study describing the antibiotic susceptibility profile of bacteria isolated from osteoarticular infections over 10years in our University Hospital, with a focus on the Staphylococcus genus.

RESULTS

A total of 3474 staphylococci were included (2373 coagulase negative staphylococci and 1101 S. aureus), 34.8% (1207/3469) of which were resistant to methicillin. Antibiotic susceptibility profiles remained quite stable between 2010 and 2019, except for rifampicin (14.1% (45/318) versus 5.7% (23/401), p=0.0001) and fluoroquinolones (35.3% (109/309) versus 20.3% (81/399), p=0.000008) for which resistance rates significantly decreased even among methicillin-resistant strains.

DISCUSSION

In spite of wide use of antibiotics in orthopaedic units, overall resistance rates did not increase over the last 10years. The prescription of these molecules in combination regimens guided by the antibiotic susceptibility patterns performed on reliable samples and on the basis of multidisciplinary discussions may explain these results.

LEVEL OF EVIDENCE

IV, retrospective study.

Infectious hazards of tatami mats

A 16-year old girl consulted for repeated axillary abscesses. The bacteriological culture yielded monomicrobial Staphylococcus aureus. Faced with these recurrent abscesses in an immunocompetent patient playing a close contact sport, the biologist suspected the strain to harbor a virulence factor explaining these recurrences.

A LAMP-based assay for the molecular detection of group B Streptococcus

PURPOSE

Streptococcus agalactiae remains a major pathogen in human health, especially in neonatal infection. Detection in pregnant women is essential to initiate intrapartum antibiotic prophylaxis. This study compared the HiberGene loop-mediated isothermal amplification (LAMP) assay to culture, the reference method, for the detection of group B Streptococcus (GBS) in pregnant women.

METHODS

This was a prospective multicenter study conducted in four French hospitals. Three hundred fifty-four non-redundant routine care vaginal swabs were analyzed by both methods, LAMP assay and culture. Clinicians and patients were blinded to the results of the LAMP assay.

RESULTS

Three hundred thirty-seven samples presented concordant results, 15 presented discordant results, and 2 were invalid using the LAMP assay (excluded from the study). Compared to culture, the LAMP assay had a sensitivity of 87.7%, a specificity of 98%, a negative predictive value of 97.6%, and a positive predictive value of 89.3%.

CONCLUSION

The HiberGene GBS LAMP assay is an easy test that possesses good performances compared with the reference method, culture. It could be used in case of emergency when a quick result is needed.

Whole genomes from bacteria collected at diagnostic units around the world 2020

The Two Weeks in the World research project has resulted in a dataset of 3087 clinically relevant bacterial genomes with pertaining metadata, collected from 59 diagnostic units in 35 countries around the world during 2020. A relational database is available with metadata and summary data from selected bioinformatic analysis, such as species prediction and identification of acquired resistance genes.

An unusual case of native aortic endocarditis due to Corynebacterium pseudodiphtheriticum

Corynebacterium pseudodiphtheriticum, a Gram-positive rod belonging the oropharynx microbiota, is usually described in pulmonary infections, especially in immunocompromised patients. This paper describes a rare case of native aortic infectious endocarditis (IE) and reviews the literature on similar cases. A 62-year-old man with rheumatic fever since childhood was hospitalized for surgical treatment of a febrile IE due to C. diphtheriticum with a large vegetation (15.8 X 8.3 mm). MALDI-TOF-MS from strain isolated in positive blood cultures identified C. pseudodiphtheriticum (2.34), and 16S rRNA sequencing from the valve sample confirmed the identification. The summary of 25 cases shows that the outcome of an IE due to C. pseudodiphtheriticum is bad. The review of the literature shows that this agent found in blood cultures in a cardiovascular context deserves to be explored meticulously because an unfavorable prognosis is frequent.

Short communication: dog bite and back pain

Capnocytophaga canimorsus is a Gram-negative rod commensal of oral cavity of dogs and cats. It can cause sepsis, septic shock, endocarditis, and meningitis associated with bites or licking wounds, especially in immunocompromised patients. Herein, we report a case of C. canimorsus spondylodiscitis linked to a dog bite in a previously healthy patient and review the literature on this pathogen.

Apyretic pulmonary oedema revealing Cardiobacterium hominis endocarditis: case report and review of literature

Cardiobacterium hominis is a member of the HACEK group of bacteria, responsible for infective endocarditis, mainly in patients with damaged or prosthetic valves. The low virulence of this organism can explain the insidious presentation and subacute or chronic progression of C. hominis infective endocarditis. Here, a 41-year-old man with a past history of surgery for a Waldhausen type aortic coarctation was hospitalised with dyspnea and chest pains revealing an acute pulmonary oedema, without fever. Transesophageal echocardiography indicated a 20 mm vegetation on biscuspid aortic valve. Six sets of blood culture were positive with Cardiobacterium hominis. In case of lack of fever, the diagnosis of infectious endocarditis is difficult because other symptoms are non-specific and biological markers of inflammatory syndrome are quiet or non-existent. This is the first case of C. hominis infectious endocarditis with a clinical presentation of acute pulmonary oedema in the literature. We report here an apyretic pulmonary oedema revealing C. hominis endocarditis and a review of the literature on apyretic infective endocarditis due to C. hominis.

Evaluation of the new BL-RED (β-Lactamase Rapid Electrochemical Detection) test in positive blood culture broths

The rapid detection of extended-spectrum β-lactamase Enterobacterales (ESBL-E) in a positive blood culture is important in order to initiate an appropriate antibiotic therapy and thus decrease mortality. We evaluated the new BL-RED (β-Lactamase Rapid Electrochemical Detection) test in 100 positive blood culture broths to detect (in ten minutes) the presence or absence of ESBL-E. The BL-RED test appears to be an easy, rapid and reliable test to detect the presence of ESBL directly in Gram negative bacilli-positive blood culture broths, with good performances (sensibility =97.3%, specificity =90.5%, predictive positive value =85.7% and predictive negative value =98.3%). This test could be useful for therapeutic decisions and adjustments of sepsis empirical antibiotic therapy, particularly in wards where the ecology is unfavorable, such as in intensive care units.

Bacteremia Due to Kosakonia cowanii in a Preterm Neonate

Objective Low-birthweight infants admitted to neonatal intensive care units are at high risk of hospital-acquired infections by opportunistic pathogens. The gut microbiota of preterm neonates lacks commensal bacteria providing a barrier against pathogens. We report a case of bacteremia due to Kosakonia cowanii in a preterm neonate.

Case Report A female baby of 680 g was delivered through a cesarean-section at 28 weeks of gestation due to intrauterine growth retardation and fetal rhythm abnormalities. On day 27, two blood cultures grew gram-negative bacilli in a context of functional ileus. No reliable identification could be obtained using matrix assisted laser desorption ionization-time of flight, biochemical reactions with the VITEK 2 GN ID card, or 16S rDNA sequencing. K. cowanii was finally identified by gyrB sequencing. The source of infection may have been either the central venous catheter or translocation from the gut microbiota. Evolution was favorable after 14 days of cefepime (combined with amikacin for 5 days) and central venous catheter removal.

Conclusion K. cowanii is a member of the Enterobacteriaceae family that was recently reclassified from the Enterobacter genus. Human infections due to K. cowanii are scarce and have mainly been associated with traumatic inoculation from plants or transient gut colonization. K. cowanii may be an underestimated opportunistic pathogen in susceptible populations such as preterm neonates.

Classification and Regression Trees for Bacterial Vaginosis Diagnosis in Pregnant Women Based on High-Throughput Quantitative PCR

Bacterial vaginosis (BV) diagnosis in pregnancy is based on the Nugent score, which consists of semiquantitation of bacterial morphotypes. Limited data exist concerning molecular-based diagnosis in asymptomatic pregnant women. Using high-throughput quantitative PCR, 34 microorganisms were screened in asymptomatic pregnant women and compared with the Nugent score. Three-hundred and four vaginal samples had a Nugent score <7 (69.9%) and 131, a Nugent score ≥7 (30.1%), consistent with BV. More pregnant women with BV share Atopobiumvaginae, bacterial vaginosis associated bacteria-2, Gardnerella spp., Mobiluncus curtisii, Mo. mulieris, Mycoplasma hominis, Ureaplasma urealyticum, Prevotella bivia, Megasphaera 1, and Megasphaera 2 in their vaginal sample. Fewer pregnant women with BV share Lactobacillus crispatus, L. gasseri, L. jensenii, and Enterococcus faecalis in their vaginal sample (P < 0.001). Classification and regression tree analysis was performed to determine which combinations of detected bacteria optimally diagnose BV in this population. A set of only four bacteria of 34 microorganisms (A. vaginae, Gardnerella spp., L. crispatus, and P. bivia) was the best combination to identify BV in a cohort of asymptomatic pregnant women, with a sensitivity of 77.1%, and specificity of 97.0% compared with the Nugent score. The quantitative PCR in the present study responds to the limits of the Nugent score by implementing an easily reproducible quantitative assay to assess the absence of BV in pregnancy.

One Outbreak Could Hide Another

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently a major worldwide concern. Guidelines have been issued regarding precautions for healthcare workers caring for SARS-CoV-2-infected patients. Despite accurate observance of infection control measures, including contact precautions, we encountered an OXA-23-producing Acinetobacter baumannii outbreak in 5 intensive care units of 10 beds each in our tertiary care teaching hospital.

Spontaneous decolonization during hospitalization in intensive care unit patients colonized by extended-spectrum beta-lactamase-producing Enterobacterales

This study aimed to analyse the frequency of occurrence of spontaneous decolonization in intensive care unit patients colonized by extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) in order to assess the added value of continuing weekly ESBL-E rectal carriage screening in these patients. In total, 49,468 weekly rectal screening samples taken from 20,846 patients over 12 years were included. Among the 4280 ESBL-E carriers, only 109 patients (2.5%) could be considered decolonized at the end of their hospitalization with at least three consecutive negative samples. Overall, 7957 samples (16.1%) were requested for patients already identified as ESBL-E carriers. Avoiding unnecessary weekly screening following positive ESBL-E colonization results could decrease nursing and laboratory work loads.

Culturing Periprosthetic Tissues in BacT/Alert® Virtuo Blood Culture Bottles for a Short Duration of Post-operative Empirical Antibiotic Therapy

Introduction: A post-operative empirical antibiotic therapy (PEAT) is required in periprosthetic joint infections. It commonly uses broad-spectrum antibiotics to cover most Gram-positive cocci and Gram-negative bacilli. It is currently continued until first microbiological results are available, no less than five days later. Methods: We performed a retrospective study in order to evaluate duration of incubation required for surgical samples using the BacT/Alert® Virtuo blood culture bottles system. Results: Among 216 surgical interventions and 199 clinical strains (53.8% staphylococci, 22,1% streptococci and enterococci, 14,6% Gram-negative bacilli, 5,5% anaerobes), 90.5% of the strains were detected between day 0 and day 2; 15 infective strains are cultured from day 3 including 8 Cutibacterium sp., 4 staphylococci, 2 streptococci and 1 Enterococcus. Conclusions: We suggest that the duration of PEAT in patients operated for a periprosthetic joint infection may be shortened to three days as Gram-negative rods are unlikely to grow after three days of culture by using BacT/Alert® Virtuo blood culture bottles. This is likely to shorten the overall length of hospital stay, to diminish the occurrence of adverse side effects, and the emergence of antimicrobial resistance. However, coverage of Gram-positive cocci should be maintained for 14 days until the definite culture results are available.

Panton-Valentine Leukocidin-Secreting Staphylococcus aureus Pneumonia Complicating COVID-19

Necrotizing pneumonia induced by Panton-Valentine leukocidin–secreting Staphylococcus aureus is a rare but life-threatening infection that has been described in patients after they had influenza. We report a fatal case of this superinfection in a young adult who had coronavirus disease.

Clinical relevance of Clostridium bacteremia: An 8-year retrospective study

Clostridium spp. are recovered from 25% of the blood culture positive with anaerobes. However, the clinical relevance of Clostridium bacteremia has been controverted in the literature, particularly for C. perfringens. We aimed to evaluate the clinical relevance of Clostridium bacteremia, either due to C. perfringens or other Clostridium species, and to identify the risk factors of mortality in these patients. A retrospective cohort study was conducted from January 2010 to April 2018. All the patients with at least one blood culture positive with any Clostridium species were included. Eighty-one patients with a least one blood culture positive with any Clostridium species were included. Seventy patients (86.4%) fulfilled the criteria for clinically relevant bacteremia. Bacteremia due to C. perfringens tended to be less clinically relevant than other Clostridium species but this was not statistically significant (76% vs 91.2%, P = 0.09). In case of clinically relevant bacteremia, the 30-day mortality rate was 31.4%. In multivariate analysis, adequate empiric antimicrobial therapy was significantly associated with survival (P = 0.03). In conclusion, bacteremia due to C. perfringens or other Clostridium species is usually clinically relevant. This finding was also supported by an improved survival at 30 days when adequate empiric antimicrobial therapy was administered.

Ceftobiprole: a potential empirical post-operative monotherapy in prosthetic joint infections

Background

This study aimed to evaluate in vitro susceptibility to ceftobiprole of clinical strains identified from prosthetic joint infections (PJIs) compared to that of the associations currently recommended for post-operative empirical antibiotic therapy (PEAT) (vancomycin with either cefepime, third-generation cephalosporin or piperacillin–tazobactam).

Methods

We performed a 1-year retrospective study on all the surgical procedures performed in our hospital for PJI. Susceptibility profiles of all the strains cultured from surgical samples were reviewed to compare ceftobiprole to current used associations.

Results

During the study period (from January 2018 to December 2018), we identified 106 patients managed for PJI and a total of 216 surgical interventions. One hundred-fifty strains were identified from intraoperative samples, excluding redundant strains. Staphylococcus spp. represented 52.7% of all strains and Enterobacteriales 13.3%. Twenty-three patients had polymicrobial infection (22%). Among 149 surgical procedures with positive culture results, ceftobiprole covered the bacterial strains in 138 (92.6%) cases. In comparison, this percentage was 94.6% for vancomycin plus cefepime (p = 0.64), 92.6% for vancomycin plus a third-generation cephalosporin in 138 cases (p = 1) and 94.6% for vancomycin plus piperacillin–tazobactam) (p = 0.64).

Conclusion

Based on antimicrobial susceptibility testing, our results suggest that ceftobiprole could be an interesting option for PEAT in PJIs, allowing the use of a single agent.

First case of fatal bacteremia due to Nocardia neocaledoniensis

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First case of bacteremia due to N.neocaledoniensis in an immunocompromised patient.

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Mass spectrometry is a discriminant technique to identify rapidly N.neocaledoniensis.

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Incubating culture media for a longer time helps to obtain definitive diagnosis and adapt antibiotics.

Nocardia neocaledoniensis is an uncommon cause of human-infections. Few cases are reported in the literature. We describe the first case of bacteremia caused by N. neocaledoniensis. This article underlines the importance of mass spectrometry for easy and rapid identification of such bacterium.

Trimethoprim susceptibility in E. coli community-acquired urinary tract infections in France

OBJECTIVES

Trimethoprim has been recently included in the French guidelines for the treatment of urinary tract infections, but no epidemiological data supports its use. We aimed to determine the trimethoprim susceptibility of Escherichia coli isolates responsible for community-acquired urinary tract infections in women of childbearing age.

MATERIALS AND METHODS

We conducted a national prospective survey. A total of 350 strains of E. coli isolated from urines in 35 laboratories were included. Antibiotic susceptibility testing was performed in each laboratory.

RESULTS

We reported a susceptibility rate of 78%, and a similar clinical categorization between trimethoprim and cotrimoxazole for 97.4% of isolates. We pointed out an association between resistance to trimethoprim and other antibiotic classes.

CONCLUSION

The results support trimethoprim as a second-line therapy based on antibiotic susceptibility testing results. We confirm that trimethoprim and cotrimoxazole susceptibility rates are very close.

Familial Transmission of emm12 Group A Streptococcus

Incidence and severity of invasive group A Streptococcus infections are of increasing concern in France and worldwide. The risk for secondary infection of close contacts is known but rarely described. We report a case of intrafamilial and life-threatening transmission of emm12 group A Streptococcus.

A fatal endocarditis case due to an emerging bacterium: Moraxella nonliquefaciens

Moraxella nonliquefaciens is a Gram-negative coccobacillus considered as a commensal organism from the upper respiratory tract, with low pathogenic potential. The phenotypical conventional identification is difficult and the matrix-assisted laser desorption/ionization time-of-flight technology has increased the resolution of identification of this bacterium. We report a fatal case of endocarditis due to M. nonliquefaciens whose identification was confirmed by 16S rRNA, and we review the literature on this pathogen in endocarditis.

In vitro susceptibility to mecillinam of Escherichia coli strains isolated from the urine of pregnant women

OBJECTIVES

Pivmecillinam is a safe beta-lactam for use in pregnancy. It has been widely used for the treatment of lower urinary tract infections (UTIs) in the Nordic countries where its efficacy, minor impact on the microbiota, and low level of resistance among the Escherichia coli strains have been proven. However, susceptibility data related to E. coli involved in asymptomatic bacteriuria and lower UTIs in pregnant women is lacking. We aimed to support the 2015 recommendations issued by the French Infectious Diseases Society (SPILF) on gestational UTI, with a particular focus on pivmecillinam.

MATERIAL AND METHODS

Antimicrobial susceptibility testing was performed by 12 hospitals with a maternity department on 235 E. coli strains isolated from the urine of pregnant women. Susceptibility to mecillinam was tested by disk diffusion method using the 2015 recommendations of the antibiogram committee of the French microbiology society (CA-SFM).

RESULTS

Global susceptibility to mecillinam was 86.4%. Susceptibility to mecillinam was 96.5% for strains susceptible to amoxicillin-clavulanic acid and 38.7% for resistant strains. All six extended-spectrum beta-lactamase-producing E. coli strains were susceptible to mecillinam.

CONCLUSION

Given the efficacy and safety of pivmecillinam during pregnancy, it may be used for the documented treatment of asymptomatic bacteriuria and acute cystitis in pregnant women. It also represents an alternative for the treatment of multidrug-resistant bacterial infections.