Phenotypic/Genotypic Profile of OXA-10-Like-Harboring, Carbapenem-Resistant Pseudomonas aeruginosa: Using Validated Pharmacokinetic/Pharmacodynamic In Vivo Models To Further Evaluate Enzyme Functionality and Clinical Implications.

In vitro MICs and in vivo pharmacodynamics of ceftazidime and cefepime human-simulated regimens (HSR) against modified carbapenem inactivation method (mCIM)-positive Pseudomonas aeruginosa isolates harboring different OXA-10-like subtypes were described. The murine thigh model assessed ceftazidime (2 g every 8 h [q8h] HSR) and cefepime (2 g and 1 g q8h HSR). Phenotypes were similar despite possessing OXA-10-like subtypes with differing spectra. Ceftazidime produced ≥1-log10 killing in all isolates. Cefepime activity was dose dependent and MIC driven. This approach may be useful in assessing the implications of ß-lactamase variants.

In Vitro Antifungal Resistance of Candida auris Isolates from Bloodstream Infections, South Africa.

Candida auris is a multidrug-resistant fungal pathogen that is endemic in South African hospitals. We tested bloodstream C. auris isolates that were submitted to a reference laboratory for national laboratory-based surveillance for candidemia in 2016 and 2017. We confirmed the species identification by phenotypic/molecular methods. We tested susceptibility to amphotericin B, anidulafungin, caspofungin, micafungin, itraconazole, posaconazole, voriconazole, fluconazole, and flucytosine using broth microdilution and Etest methods. We interpreted MICs using tentative breakpoints. We sequenced the genomes of a subset of isolates and compared them to the C. auris B8441 reference strain. Of 400 C. auris isolates, 361 (90%) were resistant to at least one antifungal agent, 339 (94%) to fluconazole alone (MICs of ≥32 µg/ml), 19 (6%) to fluconazole and amphotericin B (MICs of ≥2 µg/ml), and 1 (0.3%) to amphotericin B alone. Two (0.5%) isolates from a single patient were pan-resistant (resistant to fluconazole, amphotericin B, and echinocandins). Of 92 isolates selected for whole-genome sequencing, 77 clustered in clade III, including the pan-resistant isolates, 13 in clade I, and 2 in clade IV. Eighty-four of the isolates (91%) were resistant to at least one antifungal agent; both resistant and susceptible isolates had mutations. The common substitutions identified across the different clades were VF125AL, Y132F, K177R, N335S, and E343D in ERG11; N647T in MRR1; A651P, A657V, and S195G in TAC1b; S639P in FKS1HP1; and S58T in ERG3. Most South African C. auris isolates were resistant to azoles, although resistance to polyenes and echinocandins was less common. We observed mutations in resistance genes even in phenotypically susceptible isolates.

Klebsiella pneumoniae ST307 with blaOXA-181, South Africa, 2014-2016.

Klebsiella pneumoniae sequence type (ST) 307 is an emerging global antimicrobial drug-resistant clone. We used whole-genome sequencing and PCR to characterize K. pneumoniae ST307 with oxacillinase (OXA) 181 carbapenemase across several private hospitals in South Africa during 2014-2016. The South Africa ST307 belonged to a different clade (clade VI) with unique genomic characteristics when compared with global ST307 (clades I-V). Bayesian evolution analysis showed that clade VI emerged around March 2013 in Gauteng Province, South Africa, and then evolved during 2014 into 2 distinct lineages. K. pneumoniae ST307 clade VI with OXA-181 disseminated over a 15-month period within 42 hospitals in 23 cities across 6 northeastern provinces, affecting 350 patients. The rapid expansion of ST307 was most likely due to intrahospital, interhospital, intercity, and interprovince movements of patients. This study highlights the importance of molecular surveillance for tracking emerging antimicrobial clones.

The efficacy of pulsed-xenon ultraviolet light technology on Candida auris.

BACKGROUND: Candida auris is an emerging, often multi-resistant, yeast that causes invasive infections in healthcare settings. Patients may be colonized for months and C. auris has been shown to remain viable on surfaces for at least 14 days. It is widely considered that the environment may be a reservoir for transmission of C. auris. The efficacy of pulsed-xenon ultraviolet (PX-UV) mobile devices on C. auris has not been tested previously. In a laboratory setting, we tested efficacy of a PX-UV system on C. auris and C. parapsilosis, another candida known to be responsible for outbreaks in healthcare settings and survive for at least 28 days in the environment. METHODS: Cultures and growth of clinical strains of C. parapsilosis and C. auris was carried out in a broth liquid culture medium at 37 °C until concentration ranges 10 5-10 6 colony-forming units (CFUs) per millilitre were obtained. Glass slides were inoculated with 10 µl of C. auris stock culture and allowed to dry. Slides were positioned perpendicular to the floor at a distance of 1.25 m from the floor. Exposure time were run uninterrupted for 5-, 10- and 15-min cycles at 1- and 2-m distance. RESULTS: There was a 99.4% reduction in C. auris CFU after a 5-min cycle at 1-m distance, and 99.6% reduction after a 10-min cycle at 2-m distance. There was a 98.5% reduction in C. parapsilosis CFU after a 5-min cycle at 1-m distance, and 95.2% reduction after a 10-min cycle at 2-m distance. CONCLUSIONS: The PX-UV mobile device is easy to use and has short cycle times that makes it easier to disinfect all areas outside the room where the patient received care. Further studies are needed in hospital environment, to assess the cumulative impact of repeated sessions.

Emergence of OXA-48 and OXA-181 carbapenemases among Enterobacteriaceae in South Africa and evidence of in vivo selection of colistin resistance as a consequence of selective decontamination of the gastrointestinal tract.

This study reports on the emergence of OXA-48-like carbapenemases among isolates of Enterobacteriaceae in South Africa. In addition, the emergence during therapy of a colistin-resistant OXA-181-producing Klebsiella pneumoniae isolate was documented following selective digestive tract decontamination with oral colistin, which is therefore strongly discouraged.

Phenotypic and genetic characterization of the first two cases of extended-spectrum-cephalosporin-resistant Neisseria gonorrhoeae infection in South Africa and association with cefixime treatment failure.

OBJECTIVES: To describe the phenotypic and genetic characteristics of the first two cases of extended-spectrum cephalosporin (ESC)-resistant Neisseria gonorrhoeae in South Africa, one of which was associated with verified cefixime treatment failure. PATIENTS AND METHODS: Two ESC-resistant N. gonorrhoeae isolates were cultured from the urethral discharge of two men who have sex with men (MSM). One man reported a persistent urethral discharge that had failed to respond to previous therapy with oral cefixime. Agar dilution MICs were determined for eight antibiotics. ß-Lactam-associated resistance mutations were identified through PCR-based amplification and sequencing for several key genes: penA, mtrR and its promoter, porB1b (penB), ponA and pilQ. For molecular epidemiological characterization, full-length porB gene sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST) and multilocus sequence typing (MLST) were performed. RESULTS: Both isolates were resistant to cefixime, ciprofloxacin, penicillin and tetracycline and intermediate/resistant to azithromycin, but susceptible to ceftriaxone, gentamicin and spectinomycin. Both isolates had the type XXXIV penA mosaic allele in addition to previously described resistance mutations in the mtrR promoter (A deletion), porB1b (penB) (G101K and A102N) and ponA1 (L421P). Both isolates had an identical NG-MAST sequence type (ST4822) and MLST sequence type (ST1901). CONCLUSIONS: Both isolates were resistant to cefixime and possessed a number of identical mutations in key genes contributing to ESC resistance in N. gonorrhoeae. The two isolates contained the type XXXIV penA mosaic allele and belonged to a successful international MSM-linked multidrug-resistant gonococcal clone (MLST ST1901) associated with several cefixime treatment failures in Europe and North America.

Emergence of New Delhi metallo-beta-lactamase (NDM-1) and Klebsiella pneumoniae carbapenemase (KPC-2) in South Africa.

This report documents emergence of New Delhi metallo-beta-lactamase (NDM-1) and Klebsiella pneumoniae carbapenemase (KPC-2) in K. pneumoniae and Enterobacter cloacae in South Africa. NDM-1 producers have not been described in South Africa, and this is the first instance that KPC producers have been identified in Africa. The two patients infected with these carbapenemase-producing bacteria demised.

Best practices: Appropriate use of the new ß-lactam/ß-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam in South Africa.

Antibiotic stewardship of hospital-acquired infections because of difficult-to-treat resistant (DTR) Gram-negative bacteria is a global challenge. Their increasing prevalence in South Africa has required a shift in prescribing in recent years towards colistin, an antibiotic of last resort. High toxicity levels and developing resistance to colistin are narrowing treatment options further. Recently, two new ß-lactam/ß-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam were registered in South Africa, bringing hope of new options for management of these life-threatening infections. However, with increased use in the private sector, increasing levels of resistance to ceftazidime-avibactam are already being witnessed, putting their long-term viability as treatment options of last resort, in jeopardy. This review focuses on how these two vital new antibiotics should be stewarded within a framework that recognises the resistance mechanisms currently predominant in South Africa's multi-drug and DTR Gram-negative bacteria. Moreover, the withholding of their use for resistant infections that can be treated with currently available antibiotics is a critical part of stewardship, if these antibiotics are to be conserved in the long term.

Evaluation of the rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test for rapid colistin resistance detection in lactose non-fermenting Gram-negative bacteria.

Introduction. Colistin is one of the last-resort antibiotics for treating multidrug-resistant (MDR) or extensively drug-resistant (XDR) lactose non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii.Gap Statement. As the rate of colistin resistance is steadily rising, there is a need for rapid and accurate antimicrobial susceptibility testing methods for colistin. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test has recently been developed for rapid detection of colistin resistance in P. aeruginosa and A. baumannii.Aim. The present study aimed to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in comparison with the reference broth microdilution (BMD) method.Methodology. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test was performed using a total of 135 P. aeruginosa (17 colistin-resistant and 118 colistin-susceptible) and 66 A. baumannii isolates (32 colistin-resistant and 34 colistin-susceptible), in comparison with the reference BMD method.Results. The categorical agreement of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test with the reference BMD method was 97.5 % with a major error rate of 0 % (0/152) and a very major error (VME) rate of 10.2 %. The VME rate was higher (23.5 %) when calculated separately for P. aeruginosa isolates. The overall sensitivity and specificity were 89.8 and 100 %, respectively.Conclusion. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test performed better for A. baumannii than for P. aeruginosa.

Emergence of plasmid-mediated colistin resistance (MCR-1) among Escherichia coli isolated from South African patients.

The polymyxin antibiotic colistin is an antibiotic of last resort for the treatment of extensively drug-resistant Gram-negative bacteria, including carbapenemase-producing Enterobacteriaceae. The State of the World's Antibiotics report in 2015 highlighted South Africa (SA)'s increasing incidence of these 'superbugs' (3.2% of Klebsiella pneumoniae reported from SA were carbapenemase producers), and in doing so, underscored SA's increasing reliance on colistin as a last line of defence. Colistin resistance effectively renders such increasingly common infections untreatable.

The spread of carbapenem-resistant Enterobacteriaceae in South Africa: risk factors for acquisition and prevention.

New, effective antibiotics are only likely to become available in 15 - 20 years. To prevent deaths from untreatable Gram-negative infections in South Africa, the rights of any doctor, whether in general or in hospital practice, to indiscriminately prescribe whatever antibiotic they wish, and in whatever fashion, must be challenged. Furthermore, although prevention of the emergence and subsequent spread of carbapenem-resistant Enterobacteriaceae (CRE) has focused on acute and chronic care facilities and inter alia on antibiotic exposure in these institutions, CRE may soon become an issue within entire communities, highlighting a role for public health authorities in CRE prevention efforts.