Emergence of carbapenem non-susceptible multidrug resistant Acinetobacter baumannii strains of clonal complexes 103(B) and 92(B) harboring OXA-type carbapenemases and metallo-ß-lactamases in Southern India.

The molecular epidemiology and carbapenem resistance mechanisms of clinical isolates of Acinetobacter baumannii obtained from a south Indian tertiary care hospital were investigated by repetitive extragenic palindromic sequence PCR (REP-PCR) and multi-locus sequence typing (MLST). Analysis of resistant determinants was achieved by PCR screening for the presence of genes encoding OXA-carbapenemases, metallo-ß-lactamases (MBLs) and efflux pumps. REP-PCR generated around eight clusters of high heterogeneity; of these, two major clusters (I and V) appeared to be clonal in origin. Analysis of representative isolates from different clusters by MLST revealed that most of the isolates belonged to sequence type 103 of CC103(B) . Second most prevalent ST belonged to clonal complex (CC) 92(B) which is also referred to as international clone II. Most of the isolates were multi-drug resistant, being susceptible only to polymyxin-B and newer quinolones. Class D ß-lactamases such as blaOXA-51-like (100%), blaOXA-23-like (56.8%) and blaOXA-24-like (14.8%) were found to be predominant, followed by a class B ß-lactamase, namely blaIMP-1 (40.7%); none of the isolates had blaOXA-58 like, blaNDM-1 or blaSIM-1 . Genes of efflux-pump adeABC were predominant, most of isolates being biofilm producers that were PCR-positive for autoinducer synthase gene (>94%). Carbapenem non-susceptible isolates were highly diverse and present throughout the hospital irrespective of type of ward or intensive care unit. Although previous reports have documented diverse resistant mechanisms in A. baumannii, production of MBL and OXA-type of carbapenamases were found to be the predominant mechanism(s) of carbapenem resistance identified in strains isolated from Southern India.

Latex agglutination test (LAT) for antigen detection in the cystic fluid for the diagnosis of cystic echinococcosis.

Latex agglutination test (LAT) was standardized and evaluated to detect hydatid antigen in fluid samples aspirated from 6 surgically proved human cases of cystic echinococcosis (CE), 4 suspected human cases of CE (2 cases of cysts in the liver which were not confirmed surgically and 2 cases of pelvic cysts later confirmed as abscesses) and 7 cases of hydatid cysts of liver in cattle. Echinococcus granulosus scolices and hook lets were seen in aspirated fluid by microscopy and the characteristic germinal layer of the cyst wall was demonstrated by histopathology in 6 human hydatid cysts operated and removed by surgery. In case of cattle hydatid liver cysts no scolices or hook lets were seen in aspirated fluid as they were sterile cysts but characteristic laminated layer of the cyst wall was demonstrated by histopathology of these cysts. The LAT could detect antigen in fluid samples collected from all 6 human cases of surgically proved CE and 7 cases of hydatid cyst liver in cattle, thus showing sensitivity of 100%. The LAT could detect antigen in fluid samples collected from 2 suspected cases of CE liver in humans, which were not operated. The LAT was found to be specific. No cross reactivity was observed. The results of the study showed that LAT could be employed as a simple and rapid diagnostic procedure, as an alternate to microscopy, to confirm the hydatid etiology of a suspected cyst.