Contribution of efflux pumps, porins, and ß-lactamases to multidrug resistance in clinical isolates of Acinetobacter baumannii.

We investigated the mechanisms of resistance to carbapenems, aminoglycosides, glycylcyclines, tetracyclines, and quinolones in 90 multiresistant clinical strains of Acinetobacter baumannii isolated from two genetically unrelated A. baumannii clones: clone PFGE-ROC-1 (53 strains producing the OXA-58 ß-lactamase enzyme and 18 strains with the OXA-24 ß-lactamase) and clone PFGE-HUI-1 (19 strains susceptible to carbapenems). We used real-time reverse transcriptase PCR to correlate antimicrobial resistance (MICs) with expression of genes encoding chromosomal ß-lactamases (AmpC and OXA-51), porins (OmpA, CarO, Omp33, Dcap-like, OprB, Omp25, OprC, OprD, and OmpW), and proteins integral to six efflux systems (AdeABC, AdeIJK, AdeFGH, CraA, AbeM, and AmvA). Overexpression of the AdeABC system (level of expression relative to that by A. baumannii ATCC 17978, 30- to 45-fold) was significantly associated with resistance to tigecycline, minocycline, and gentamicin and other biological functions. However, hyperexpression of the AdeIJK efflux pump (level of expression relative to that by A. baumannii ATCC 17978, 8- to 10-fold) was significantly associated only with resistance to tigecycline and minocycline (to which the TetB efflux system also contributed). TetB and TetA(39) efflux pumps were detected in clinical strains and were associated with resistance to tetracyclines and doxycycline. The absence of the AdeABC system and the lack of expression of other mechanisms suggest that tigecycline-resistant strains of the PFGE-HUI-1 clone may be associated with a novel resistance-nodulation-cell efflux pump (decreased MICs in the presence of the inhibitor Phe-Arg ß-naphthylamide dihydrochloride) and the TetA(39) system.

Klebsiella pneumoniae strains producing extended-spectrum beta-lactamases in Spain: microbiological and clinical features.

Extended-spectrum ß-lactamases (ESBL) of the CTX-M, SHV, and TEM families were recognized in 76 (67%), 31 (27%), and 6 (5%) isolates, respectively, among 162 ESBL-producing Klebsiella pneumoniae (ESBL-Kp) strains obtained in a multicenter study in Spain. Predisposing factors for ESBL-Kp acquisition included invasive procedures, mechanical ventilation, and previous antimicrobial use.

Clinical utility of anti-CCP antibodies in the differential diagnosis of elderly-onset rheumatoid arthritis and polymyalgia rheumatica.

BACKGROUND: In a significant number of patients the differential diagnosis between elderly-onset rheumatoid arthritis (EORA) and polymyalgia rheumatica (PMR) is very difficult because of the lack of specific serum markers. Anti-cyclic citrullinated peptide antibodies (anti-CCP Abs) have recently been shown to be highly specific for rheumatoid arthritis (RA). This is the first study addressing the utility of these antibodies in the differential diagnosis between EORA and PMR. METHODS: Serum samples from 57 EORA patients and 49 PMR patients were studied for the presence of anti-CCP Abs and rheumatoid factor (RF). As controls, samples from 41 RA patients (age at onset <60 yr) and 24 aged healthy subjects were analysed. RESULTS: Sixty-five per cent of EORA patients had anti-CCP Abs, whereas none of the PMR patients or the aged healthy subjects was positive for those antibodies. Ten of the EORA patients started with polymyalgic symptoms and two of them were positive for anti-CCP Abs. Interestingly, there was a significant correlation between anti-CCP Abs and RF in EORA but not in young RA patients. CONCLUSIONS: The presence of anti-CCP Abs in a patient with clinical symptoms of PMR must be interpreted as highly suggestive of EORA.

Molecular analysis of HLA allelic frequencies and haplotypes in Jordanians and comparison with other related populations.

Twenty alleles for the locus human leukocyte antigen (HLA-A) and 46 for the HLA-B locus were detected in Jordanians. This indicates the existence of high polymorphism in this area. The most frequent HLA class I alleles found were A*0201 (0.1344), B*0713 (0.1724), and C*0502 (0.1793). Twenty-six different alleles in the Jordanian population were identified for the DRB1 locus being the DRB1*0704 (0.2552), DRB1*0401 (0.1965), and DRB1*1501 (0.0896) the most frequent. Common DQA1 alleles were DQA1*0201 (0.2690), DQA1*0301 (0.2414), and DQA1*0501 (0.1724). Three-loci haplotype heterogeneity was common: 38 HLA class II haplotypes were identified, of which the most frequently observed was DRB1*0401-DQA1*0301-DQB1*0302 (0.1793). In addition, as expected, 220 different five-loci haplotypes with several unusual allelic combinations were observed, although many of them are pan-European haplotypes. The most frequent five-loci haplotype was the A30-B7-DRB1*03-DQA1*0501-DQB1*0201 (0.0138). It seems that the specific Jordanian haplotypes are the following: the A31-B7-DRB1*04/07-DQA1*0301/0201-DQB1*0302/0202 haplotypes (0.0103) and the A1-B7-DRB1*07-DQA1*0201-DQB1*0202, A2-B7-DRB1*04-DQA1*0301-DQB1*0302, A11-B7-DRB1*07-DQA1*0201-DQB1*0201 haplotypes but at lower frequencies (0.007). A tree analysis of HLA class I and class II alleles were made for several Caucasian populations and individual genetic distances calculated. The haplotype frequencies, genetic distances, and dendrograms do not reveal great differences as compared with those in other Mediterranean countries and Western Europeans populations. Our results suggest that both HLA class I and class II polymorphism (but especially the former) of the Jordanian population demonstrates considerable heterogeneity, which reflects ancient and recent admixture with neighboring populations, and important human migratory trends throughout the history.