The increasing emergence of antibiotic-resistant bacterial pathogens represents a serious risk to human health and the entire health care system. Many currently circulating strains of Acinetobacter baumannii exhibit resistance to multiple antibiotics. A key limitation in combating A. baumannii is that our understanding of the molecular mechanisms underlying the pathogenesis of A. baumannii is lacking. To identify potential virulence determinants of a contemporary multidrug-resistant isolate of A. baumannii, we used transposon insertion sequencing (TnSeq) of strain AB5075. A collection of 250,000 A. baumannii transposon mutants was analyzed for growth within Galleria mellonella larvae, an insect-based infection model. The screen identified 300 genes that were specifically required for survival and/or growth of A. baumannii inside G. mellonella larvae. These genes encompass both known, established virulence factors and several novel genes. Among these were more than 30 transcription factors required for growth in G. mellonella. A subset of the transcription factors was also found to be required for resistance to antibiotics and environmental stress. This work thus establishes a novel connection between virulence and resistance to both antibiotics and environmental stress in A. baumannii.

This study demonstrates the excellent diagnostic accuracy of the Xpert MTB/RIF test in patients with tuberculous lymphadenitis. The test sensitivity and specificity were 96.7% (95% confidence interval [CI], 86.6 to 100%) and 88.9% (95% CI, 69.6 to 100%), respectively, and it correctly identified 6/6 (100%) of the cytology smear-negative/culture-positive cases and 1 of 2 (50%) rifampin-resistant cases.Tuberculous lymphadenitis is the most common extrapulmonary manifestation of tuberculosis (TB) (4,8), and the majority of cases have no active lung involvement. Fineneedle aspiration biopsy (FNAB) offers a feasible and safe option for specimen collection (11,15). The use of cytology together with the confirmation of acid fastness by ZiehlNeelsen (ZN) staining and Papanicolaou stain-induced fluorescence microscopy as well as mycobacterial detection by culture offers excellent yields (13, 14) but remains limited by the absence of species confirmation, slow turnaround times, and/or lack of drug resistance guidance. Conventional microbiological culture and drug susceptibility testing are not always available and in rare instances may take 6 weeks or longer (10).The World Health Organization (WHO)-endorsed Xpert MTB/RIF combines sample processing and real-time PCR in a fully automated platform and detects Mycobacterium tuberculosis complex and rifampin resistance in less than 2 h (2, 3, 9). Xpert MTB/RIF has been used successfully on various extrapulmonary specimens, including urine and stool (6), but has not been rigorously evaluated with the use of tissue specimens, such as FNAB specimens.To determine the diagnostic utility of the Xpert MTB/RIF, FNAB specimens were collected from 50 consenting patients by aspirating two passes of a 23-or 25-gauge needle attached to a 10-ml syringe. Two smears were prepared from each aspirate, one fixed with commercial cytology fixative for Papanicolaou staining and evaluation by fluorescence microscopy and the other air dried for Giemsa and subsequent ZN staining.Smears were evaluated for adequacy and for a morphological diagnosis, and cases were excluded from the analysis if either one or both passes had inadequate cellular material on smears. Both ZN and Papanicolaou stain-induced fluorescence microscopy evaluations were performed for direct detection of mycobacteria on all specimens. Residual material from one of the aspirates was rinsed in a mycobacterial growth indicator tube (MGIT 960; Becton Dickinson) by aspirating a small volume of fluid into the syringe and expressing it back into the MGIT 960 tube, followed by incubation in a MGIT 960 instrument for mycobacterial culture. Positive cultures were identified as belonging to the Mycobacterium tuberculosis complex, and genotypic drug susceptibility testing was done using the genotype MTBDRplus assay (Hain Lifescience, Germany) (1).The residual material from the remaining aspirate was rinsed as described above into 0.7 ml sterile phosphate-buffered saline (PBS) in a 10-ml headspace glass vial sealed with a TFE/Sil Septa and alumin...

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. CASE REPORTS

ObjectiveTo describe an outbreak of multi-resistant Pseudomonas aeruginosa bloodstream infections (MRPA-BSI) that occurred in the haematology ward of a tertiary academic hospital in Cape Town, South Africa, and determine risk factors for acquisition of MRPA-BSI.MethodsThe outbreak investigation included a search for additional cases, review of patient records, environmental and staff screening, molecular typing using pulsed-field gel electrophoresis (PFGE) and Multi-locus sequencing (MLST) and a retrospective case-control study.ResultsTen MRPA-BSI cases occurred in the haematology ward between January 2010 and January 2011. The case fatality rate was 80%. Staff screening specimens were negative for MRPA and an environmental source was not identified. PFGE showed that 9/10 isolates were related. MLST showed that 3 of these 9 isolates belonged to Sequence type (ST) 233 while the unrelated isolate belonged to ST260.ConclusionWe have described an outbreak of MRPA-BSI occurring over an extended period of time among neutropenic haematology patients. Molecular typing confirms that the outbreak was predominantly due to a single strain. The source of the outbreak was not identified, but the outbreak appears to have been controlled following intensive infection control measures.

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FNAB and Xpert MTB/RIF enable a rapid diagnosis in pediatric mycobacterial lymphadenitis, expediting appropriate treatment and potentially preventing morbidity and mortality.

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