In vitro activity of ceftaroline against bacterial pathogens isolated from patients with skin and soft tissue and respiratory tract infections in the Middle East and Africa: AWARE global surveillance programme 2015-2018

Antimicrobial resistance profile of Staphylococcus aureus isolated from patients, healthcare workers, and the environment in a tertiary hospital in Addis Ababa, Ethiopia

Staphylococcus aureus infection and colonization in patients may be transmitted to healthcare providers and the environment and subsequently cause healthcare-associated infections in other patients. Pathogenic S. aureus strains produce virulence factors, such as Panton-Valentine Leukocidin (PVL), that contribute to the severity of infections and aid in their spread. The emergence of antimicrobial resistance (AMR) is additional concern with respect to S. aureus infection. In this study, the virulence genes and antibiotic resistance profiles of S. aureus were characterized from patients' clinical isolates, healthcare workers' (HCWs') nasal colonization screenings, and the environment at a tertiary healthcare hospital in Addis Ababa, Ethiopia. A total of 365 samples were collected from September 2021 to September 2022: 73 patients' clinical specimens, 202 colonization screenings from HCWs, and 90 hospital environment's swabs. Fifty-one (25.2%) HCW and 10/90 (11.1%) environment S. aureus isolates were identified. Among the 134 isolates, 10 (7.5%) were methicillin-resistant S. aureus (MRSA). Three (4.1%), five (9.8%), and two (20.0%) of the MRSA isolates were identified from the patients, HCWs, and the environment, respectively. Overall, 118 (88.1%) were ampicillin and penicillin resistant; 70 (52.2%) were trimethoprim sulfamethoxazole resistant; and 28 (20.9%) were erythromycin resistant. S. aureus isolates from patients were more resistant to antibiotics than isolates from HCWs or the hospital environment (p<0.05). A total of 92/134 (68.6%) isolates possessed the lukfF-PV gene, which was identified in 62 (85.0%), 26 (51.0%), and 4 (40.0%) of the patient, HCWs, and the environment, respectively. The proportion of lukfF-PV gene containing S. aureus isolated from patient samples was statistically significant. Four (40.0%) of the MRSA isolates also had the lukfF-PV gene. The identification of highly AMR and virulence factors from patients, HCWs and the environment is concerning. Further studies are needed to identify potential transmission links and improve infection prevention and control.

Systematic review of ceftaroline fosamil in the management of patients with methicillin-resistant Staphylococcus aureus pneumonia

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an array of problematic community- and healthcare-acquired infections, including pneumonia, and is frequently associated with severe disease and high mortality rates. Standard recommended treatments for empiric and targeted coverage of suspected MRSA in patients with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP), are vancomycin and linezolid. However, adverse events such as acute kidney injury and Clostridium difficile infection have been associated with these antibiotics. Ceftaroline fosamil is a β-lactam/extended-spectrum cephalosporin approved for the treatment of adults and children with CAP and complicated skin and soft tissue infections. Ceftaroline has in vitro activity against a range of common Gram-positive bacteria and is distinct among the β-lactams in retaining activity against MRSA. Due to the design of the pivotal randomised controlled trials of ceftaroline fosamil, outcomes in patients with MRSA CAP were not evaluated. However, various reports of real-world outcomes with ceftaroline fosamil for pneumonia caused by MRSA, including CAP and HAP/VAP, been published since its approval. A systematic literature review and qualitative analysis of relevant publications was undertaken to collate and summarise relevant published data on the efficacy and safety of ceftaroline fosamil in patients with MRSA pneumonia. While relatively few real-world outcomes studies are available, the available data suggest that ceftaroline fosamil is a possible alternative to linezolid and vancomycin for MRSA pneumonia. Specific scenarios in which ceftaroline fosamil might be considered include bacteraemia and complicating factors such as empyema.

In Vitro Activity of Ceftaroline and Comparators against Bacterial Isolates Collected Globally from Patients with Skin and Soft Tissue Infections: ATLAS Program 2019-2020

The objective of this study was to assess the in vitro activity of ceftaroline and a panel of comparator agents against isolates causing skin and soft tissue infections (SSTIs) collected in Africa/Middle East, Asia-Pacific, Europe, and Latin America from 2019-2020. Minimum inhibitory concentrations (MIC) were determined using European Committee on Antimicrobial Susceptibility Testing criteria. All the methicillin-susceptible Staphylococcus aureus (MSSA) isolates were susceptible to ceftaroline. Across all regions, ceftaroline demonstrated potent activity against methicillin-resistant S. aureus (MRSA, susceptibility 89.5-93.7%) isolates. Susceptibility to vancomycin, daptomycin, linezolid, teicoplanin, trimethoprim sulfamethoxazole, and tigecycline was ≥94.1% in MSSA and MRSA isolates. Against β-hemolytic streptococci isolates, ceftaroline demonstrated very potent activity (MIC90 0.008-0.03 mg/L) across all regions. All β-hemolytic streptococci isolates were susceptible to linezolid, penicillin, and vancomycin (MIC90 0.06-2 mg/L). Among the extended-spectrum β-lactamases (ESBL)-negative Enterobacterales tested (E. coli, K. pneumoniae, and K. oxytoca), susceptibility to ceftaroline was high (88.2-98.6%) in all regions. All ESBL-negative Enterobacterales were susceptible to aztreonam. Potent activity was observed for amikacin, cefepime, and meropenem (94.1-100%) against these isolates. Overall, ceftaroline showed potent in vitro activity against isolates of pathogens causing SSTIs. Continuous surveillance of global and regional susceptibility patterns is needed to guide appropriate treatment options against these pathogens.

Clinical evidence supporting ceftaroline fosamil and ceftobiprole for complicated skin and soft tissue infections

PURPOSE OF REVIEW

Ceftaroline and ceftobiprole are advanced generation cephalosporins with activity against methicillin-resistant Staphylococcus aureus (MRSA). This review summarizes their clinical efficacy for complicated skin and soft tissue infections (cSSTIs).

RECENT FINDINGS

Both these agents retain excellent in vitro activity against both MRSA and Gram-negative isolates from patients with CSSTIs. Both these agents are registered for the management of cSSTIs based on the results of large scale phase III noninferiority trials. Ceftaroline and ceftobiprole are noninferior to the combination of vancomycin and aztreonam as this was assessed by their clinical cure rate at the test-of-cure visits. Furthermore, ceftobiprole is noninferior to comparators for the achievement of early clinical success at 72 h. Ceftaroline achieves 81% clinical cure against diabetic foot infections.

SUMMARY

Ceftaroline and ceftobiprole can be used as monotherapy for the treatment of cSSTIs.

Evaluation of Phenotypic Tests to Detect Extended-Spectrum β-Lactamase (ESBL)-Producing Klebsiella oxytoca Complex Strains

Klebsiella oxytoca complex (KoC) species may overproduce their chromosomal class A OXY β-lactamases, conferring reduced susceptibility to piperacillin-tazobactam, expanded-spectrum cephalosporins and aztreonam. Moreover, since clavulanate maintains its ability to inhibit these enzymes, the resulting resistance phenotype may falsely resemble the production of acquired extended-spectrum β-lactamases (ESBLs). In this work, a collection of 44 KoC strains of human and animal origin was characterized with whole-genome sequencing (WGS) and broth microdilution (BMD) susceptibility testing. Comparison of ESBL producers (n = 11; including CTX-M-15 [n = 6] and CTX-M-1 [n = 5] producers) and hyperproducers of OXYs (n = 21) showed certain phenotypic differences: piperacillin-tazobactam (MIC_90s: 16 versus >64 μg/mL), cefotaxime (MIC_90s: 64 versus 4 μg/mL), ceftazidime (MIC_90s: 32 versus 4 μg/mL), cefepime (MIC_90s: 8 versus 4 μg/mL) and associated resistance to non-β-lactams (e.g., trimethoprim-sulfamethoxazole: 90.9% versus 14.3%, respectively). However, a clear phenotype-based distinction between the two groups was difficult. Therefore, we evaluated 10 different inhibitor-based confirmatory tests to allow such categorization. All tests showed a sensitivity of 100%. However, only combination disk tests (CDTs) with cefepime/cefepime-clavulanate and ceftazidime/ceftazidime-clavulanate or the double-disk synergy test (DDST) showed high specificity (100%, 95.5%, and 100%, respectively). All confirmatory tests in BMD or using the MIC gradient strip did not perform well (specificity, ≤87.5%). Of note, ceftazidime/ceftazidime-avibactam tests also exhibited low specificity (CDT, 87.5%; MIC gradient strip, 77.8%). Our results indicate that standard antimicrobial susceptibility profiles can raise some suspicion, but only the use of cefepime/cefepime-clavulanate CDT or DDST can guarantee distinction between ESBL-producing KoC strains and those hyperproducing OXY enzymes.

New drugs for methicillin-resistant Staphylococcus aureus skin and soft tissue infections

PURPOSE OF REVIEW

Staphylococcus aureus is a pathogen incriminated in skin and soft tissue infections (SSTIs), with methicillin-resistant S. aureus (MRSA) becoming the predominant cause and representing a significant burden to the healthcare system. The last updated Infectious Diseases Society of America (IDSA) guidelines concerning MRSA infections and SSTIs management were published in 2011 and 2014, respectively. The UK updated guidelines for MRSA infection treatment were published in 2021. Older treatment options may be associated with toxicity and require frequent dosing. There is a paucity of recent reviews on the armamentarium of new agents for MRSA SSTIs treatment.

RECENT FINDINGS

Since 2005, several new antibiotics received a fast-track approval by the Food and Drug Administration (FDA) for SSTI treatment. These drugs include delafloxacin, omadacycline, tedizolid, ceftaroline, dalbavancin, oritavancin and telavancin. In this manuscript, we will review the data that led to these new drugs approval and discuss their advantages and disadvantages in MRSA SSTIs management.

SUMMARY

MRSA is a major cause of SSTIs. Several novel therapies covering MRSA were FDA-approved for SSTIs. However, the current IDSA guidelines for MRSA infection and SSTIs as well as the recently published UK guidelines on MRSA treatment only consider these drugs as alternative choices or do not mention them at all.

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic bla_OXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. bla_KPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

Evaluation of the in vitro activity of ceftaroline, ceftazidime/avibactam and comparator antimicrobial agents against clinical isolates from paediatric patients in Kuwait: ATLAS data 2012-19

OBJECTIVES

To report antimicrobial resistance data for Gram-positive and Gram-negative pathogens isolated from paediatric patients in three hospitals in Kuwait during 2012-19.

METHODS

In vitro activity of antimicrobials against isolates from documented infections was determined using CLSI broth microdilution method and breakpoints at a central laboratory. Enterobacterales and Pseudomonas aeruginosa isolates were screened for β-lactamases using multiplex PCR assays. Phenotypic determination of resistance in Haemophilus influenzae and Gram-positive isolates was performed using standard methodologies.

RESULTS

Among 515 Enterobacterales isolates, 29.3% were ESBL-positive; susceptibility was highest to amikacin, ceftazidime/avibactam and meropenem (≥97.4%), regardless of ESBL status. CTX-M-15 was identified in 87.1% of ESBL-positive Escherichia coli and 84.2% of ESBL-positive Klebsiella pneumoniae isolates. Of 111 P. aeruginosa isolates, 9.9% were MDR and 12.6% meropenem-resistant (MEM-R). Amikacin and ceftazidime/avibactam had the highest susceptibility rates in the overall group (≥92.8%), with reduced rates among MDR and MEM-R isolates. All 269 MRSA and 180 MSSA isolates were susceptible to daptomycin, linezolid, teicoplanin, tigecycline and vancomycin. All MSSA and 99.3% of MRSA were ceftaroline susceptible. All 168 pneumococcal isolates were susceptible to ceftaroline, linezolid, tigecycline and vancomycin. H. influenzae and Streptococcus pyogenes ceftaroline susceptibility rates were ≥93.3% and ≥95.6%.

CONCLUSIONS

Most isolates of Enterobacterales (including resistant phenotypes) and P. aeruginosa from Kuwait during 2012-19 were susceptible to ceftazidime/avibactam. Ceftaroline was active against most Gram-positive isolates, including resistant phenotypes, and ESBL-negative Enterobacterales. These results indicate that novel antibiotics such as ceftazidime/avibactam and ceftaroline represent valuable treatment options for paediatric infections, including those caused by MDR organisms.