Clinical microbiology procedures handbook, 2nd ed Henry D. Isenberg,Ed. in chief + section eds. Washington DC: ASM Press,American Society Press for Microbiology; 2004. ISBN 1-55581-243-0 set; 2298 pages + index; $199.95.

Amoxicillin/clavulanate has recently undergone formulation changes (XR and ES-600) that represent 14:1 and 16:1 ratios of amoxicillin/clavulanate. These ratios greatly differ from the 2:1 ratio used in initial formulations and in vitro susceptibility testing. The objective of this study was to determine if the reference method using a 2:1 ratio accurately reflects the susceptibility to the various clinically used amoxicillin/clavulanate formulations and their respective serum concentration ratios. A collection of 330 Haemophilus influenzae strains (300 beta-lactamase-positive and 30 beta-lactamase-negative) and 40 Moraxella catarrhalis strains (30 beta-lactamase-positive and 10 beta-lactamase-negative) were tested by the broth microdilution method against eight amoxicillin/clavulanate combinations (4:1, 5:1, 7:1, 9:1, 14:1, and 16:1 ratios; 0.5 and 2 microg/mL fixed clavulanate concentrations) and the minimum inhibitory concentration (MIC) results were compared with those obtained with the reference 2:1 ratio testing. For the beta-lactamase-negative strains of both genera, there was no demonstrable change in the MIC values obtained for all ratios analyzed (2:1 to 16:1). For the beta-lactamase-positive strains of H. influenzae and M. catarrhalis, at ratios >or=4:1 there was a shift in the central tendency of the MIC scatterplot compared with the results of testing 2:1 ratio. As a result, there was a 2-fold dilution increase in the MIC(50) and MIC(90) values, most evident for H. influenzae and BRO-1-producing M. catarrhalis strains. For beta-lactamase-positive strains of H. influenzae, the shift resulted in a change in the interpretive result for 3 isolates (1.0%) from susceptible using the reference method (2:1 ratio) to resistant (8/4 microg/mL; very major error) at the 16:1 ratio. In addition, the number of isolates with MIC values at or 1 dilution lower than the breakpoint (4/2 microg/mL) increased from 5% at 2:1 ratio to 32-33% for ratios 14:1 and 16:1. Our results indicate that, for the beta-lactamase-positive strains of H. influenzae and M. catarrhalis, the results of the amoxicillin/clavulanate reference 2:1 ratio testing do not accurately represent all the currently licensed formulations. Pharmacokinetic/pharmacodynamic (PK/PD) target attainment might be compromised when higher amoxicillin/clavulanate ratios are used clinically. With a better understanding of PK/PD parameters, reevaluation of the amoxicillin/clavulanate in vitro susceptibility testing should be considered by the standardizing authorities to reflect the licensed formulations and accurately predict clinical outcomes.     

Factors associated with patient and health system delays in the diagnosis of tuberculosis in South India.

OBJECTIVES: To investigate the factors associated with delay in 1) care-seeking (patient delay), and 2) diagnosis by health providers (health system delay), among smear-positive tuberculosis patients, before large-scale DOTS implementation in South India. METHODS: New smear-positive patients were interviewed using a structured questionnaire. RESULTS: Among 531 participants, the median patient, health system and total delays were 20, 23 and 60 days, respectively. Twenty-nine per cent of patients delayed seeking care for > 1 month, of whom 40% attributed the delay to their lack of awareness about TB. Men postponed seeking care for longer periods than women (P = 0.07). In multivariate analysis, the patient delay was greater if the patient had initially consulted a government provider (adjusted odds ratio [AOR] 2.2, P < or = 0.001), resided at a distance >2 km from a health facility (AOR 1.6, P = 0.04), and was an alcoholic (AOR 1.6, P = 0.04). Health system delay was >7 days among 69% of patients. Factors associated with health system delay were: first consultation with a private provider (AOR 4.0, P < 0.001), a shorter duration of cough (AOR 2.6, P = 0.001), alcoholism (P = 0.04) and patient's residence >2 km from a health facility (AOR 1.8, P = 0.02). The total delay resulted largely from a long patient delay when government providers were consulted first, and a long health system delay when private providers were consulted first. CONCLUSION: Public awareness about chest symptoms and the availability of free diagnostic services should be increased. Government and private physicians should be educated to be aware about the possibility of tuberculosis when examining out-patients. Effective referrals for smear microscopy should be developed between private and public providers.     

Examination of Association with Candidate Genes for Diabetic Nephropathy in a Mexican American Population

Background and objectives: Diabetic nephropathy (DN) is a multifactorial complication characterized by persistent proteinuria in susceptible individuals with type 1 and type 2 diabetes. Disease burden in people of Mexican-American descent is particularly high, but there are only a few studies that characterize genes for DN in this ethnic group. Two genes, carnosine dipeptidase 1 (CNDP1) and engulfment and cell motility 1 (ELMO1) previously showed association with DN in other ethnic groups. CNDP1 and ELMO1 were examined along with eight other genes that are less well characterized for DN in a new study of Mexican-Americans.Design, setting, participants, & measurements: The target sample was patients of Mexican-American ancestry collected from three centers: 455 patients with DN and 437 controls with long-term diabetes but no incident nephropathy. Forty-two, 227, and 401 single nucleotide polymorphisms (SNPs) in CNDP1, ELMO1, and the other eight genes, respectively, were examined.Results: No region in CNDP1 or ELMO1 showed significant P values. Of the other eight candidate genes, an association of DN with a SNP pair, rs2146098 and rs6659783, was found in hemicentin 1 (HMCN1) (unadjusted P = 6.1 × 10⁻⁵). Association with a rare haplotype in this region was subsequently identified.Conclusions: The associations in CNDP1 or ELMO1 were not replicable; however, an association of DN with HMCN1 was found. Additional work at this and other loci will enable refinement of the genetic hypotheses regarding DN in the Mexican-American population to find therapies for this debilitating disease.Diabetic nephropathy (DN) is the main cause of ESRD in the United States (1). The disease burden in people of Mexican-American descent is particularly high (1), but there are only a limited number of studies that have characterized genes for DN in this ethnic group. Recently, two genes, carnosine dipeptidase 1 (CNDP1) and engulfment and cell motility 1 (ELMO1), were reported to be associated with DN (2–5). Janssen et al. (4) reported an association between DN and a microsatellite marker, D18S880, in CNDP1 among type 1 and type 2 diabetic patients from four different countries, and Freedman et al. (2) reported its replication among type 2 diabetic Caucasian patients. Shimazaki et al. (5) reported an association in the Japanese population between DN and ELMO1, which includes rs741301 as the most significant single nucleotide polymorphism (SNP).Here, we study ten candidate genes for their association with DN in the Mexican-American population. We attempt to replicate the previous associations of CNDP1 and ELMO1 with a sample size that is similar or greater than previously used (2–5). In addition, we study the following eight genes, which are good biologic candidates but have not been studied extensively: hemicentin 1 (HMCN1), complement factor H (CFH), α-2Heremans-Schmid-glycoprotein (AHSG), caspase 3 (CASP3), heat shock 70-kD protein 1A (HSPA1A), heat shock 27-kD protein 1 (HSPB1), caspase 12 (CASP12), and heme oxygenase (decycling) 1 (HMOX1).HMCN1 was shown to be associated with change in calculated GFR (6), but its role in DN has never been examined. CFH is long known to play a role in atypical hemolytic uremia and membranoproliferative GN, but its involvement in DN has not been evaluated. AHSG is reported to be associated with type 2 diabetes and dyslipidemia, it inhibits insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 (7), and it has been identified as a marker of acute kidney injury (8). Its serum concentration is increased in nondialyzed patients with DN (9) and is low in patients with ESRD (10). High serum levels are associated with insulin resistance (11). HSPB1, also known as HSP27, is involved in the regulation of cell adhesion and invasion (12), regulates actin cytoskeleton turnover, and has anti-apoptotic and antioxidant properties in a wide variety of cells and tissues (13). A mutation in HSPB1 causing a variant of Charcot-Marie-Tooth disease is associated with the development of focal and segmental glomerulosclerosis (14). HMOX1, also known as HO-1, provides antioxidant adaptive functions in response to renal injury (15) and is associated with the degree of renal failure in DN (16). CASP3 and CASP12 mediate apoptotic cell death and were chosen as candidate genes because of their relevance to DN (17,18). Finally, HSPA1A was chosen because of its cellular protectant role in the unfolded protein response (19).Our study aimed to replicate the previous association of the two genes with DN and/or discover new associations at the other eight genes of biologic importance by contrasting the genotype frequencies of SNPs in these ten genes between cases and controls after allowing for relevant covariates.     

CALLA negative precursor B lymphoblastic leukemia with MLL gene translocation and an unusual FISH signal pattern

Rearrangements of the mixed lineage leukemia (MLL) gene at 11q23 commonly occur in infants with CALLA negative B lymphoblastic leukemia (B-ALL). Most often, these are detected by conventional karyotyping; however, fluorescent in-situ hybridization (FISH) with the help of a dual-color break-apart probe is used to identify cryptic translocations. When there is an MLL gene translocation, the usual FISH signal pattern is 1 red-1 green-1 yellow fusion signal pattern. We present a case of an infant with CALLA negative precursor B-ALL with a characteristic translocation t(4;11) (q21;q23), however, with an unusual MLL FISH signal pattern.