Molecular characterisation and control of Acinetobacter baumannii isolates resistant to multi-drugs emerging in inter-intensive care units

BACKGROUND

A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred among intensive care units (ICU) (surgery, medical, cardiovascular surgery, coronary unit) of Recep Tayyip Erdogan University Medical School (Rize, Turkey) between January 2011 and May 2012. The identification of isolates and clonal relation among them were investigated by molecular techniques.

METHODS

A total of 109 AB isolates were obtained from 64 clinical materials from 54 ICU patients and 3 from the hands of healthcare workers (HCWs) of 42 environmental samples. The isolates were identified by 16S rDNA sequencing and OXA- specific PCR. The clonal relation between isolates was investigated by PFGE methods using ApaI restriction enzyme.

RESULTS

All isolates were determined as AB by 16S rDNA sequencing and OXA-spesific PCR. While the blaOXA-51-like gene was amplified in all isolates, the blaOXA-23-like gene was amplified from 103 isolates. The PFGE pattern generated 9 pulsotypes and showed that the isolates from patients, HCWs, and the environment were genetically related. In 7 of these pulsotypes, there were 107 strains (98%) showing similar PFGE profiles that cannot be distinguished from each other, ranging from 2 to 53. The remaining 2 pulsotypes were comprised of strains closely associated with the main cluster. Two major groups were discovered with similarity coefficient of 85% and above. The first group consisted of 97 strains that are similar to each other at 92.7% rate, and the second group consisted of 12 strains that are 100% identical.

CONCLUSIONS

The common utilization of the blood gas device among ICU was the reason for the contamination. AB strains can remain stable for a long period of time, although due to the disinfection procedures applied in hospitals, there is a small chance that the same clone might reappear and cause another epidemic. For that reason, the resistance profiles of the strains must be continuously followed with amplification-based methods, and these methods should be used to support the PFGE method in the short term.

MAP2K1-driven mixed Langerhans cell histiocytosis, Rosai-Dorfman-Destombes disease and Erdheim-Chester disease, clonally related to acute myeloid leukemia

Mixed histiocytoses are a rare and recently recognized subset of histiocytic disorders that may involve the skin, characterized by the synchronous or metachronous development of lesions with Langerhans and/or non-Langerhans cell histiocytosis histopathological features. Around 10% of patients diagnosed with histiocytosis may develop a hematological malignancy, often with dramatic prognostic consequences. We hereby describe the exceptional case of a patient developing a MAP2K1-driven mixed histiocytosis with Langerhans cell histiocytosis, Rosai-Dorfman-Destombes disease, and Erdheim-Chester disease features and cutaneous involvement, progressing to a fatal and clonally-related acute myeloid leukemia. We reviewed the literature on similar cases and discussed the histopathological difficulties in their diagnosis and their clinical-pathological features.

Investigation of the clonal associations in Acinetobacter Baumannii strains isolated from the respiratory samples of patients in a tertiary research hospital

Objective

The blaOXA resistance genes and ISAba1 were examined in 70 samples from lower respiratory tract of hospitalized patients.

Materials and Methods

Of the 67 isolates obtained, almost half (46.3%) of them were from endotracheal aspirate, and most were collected from the intensive care units of the reanimation (37.3%) and internal medicine (32.8%) units.

Results

Three samples from the internal medicine intensive care unit had positive cultures. Of the multidrug resistant (MDR) samples, 70 isolates (>50%) were moderately sensitive, while fewer (10%) were resistant to tigecycline. In contrast, 100% were sensitive to colistin. All strains were found to be positive for blaOXA-23-like and blaOXA-51-like genes, whereas no blaOXA-40-like and blaOXA-58-like genes were detected. The ISAba1 positivity rate was 90.0%. Pattern 5 was mainly identified among the 22 different patterns. Of note, 50% of Pattern 5 was found in the patients of the internal medicine intensive care unit, and a third was associated with ventilator-associated pneumonia. Importantly, the internal medicine unit's equipment was found to be culture positive.

Conclusion

Findings obtained from this study suggest that isolates can easily spread through the hospital via isolate cross-contamination caused by health personnel. These contaminating isolates may be able to maintain their presence within the hospital for a long time.