Multiple antibiotic-resistance mechanisms including a novel combination of extended-spectrum beta-lactamases in a Klebsiella pneumoniae clinical strain isolated in Argentina

Klebsiella pneumoniae M1803, isolated from a paediatric patient with chronic urinary infection, presented nine antimicrobial resistance mechanisms harboured on two conjugative megaplasmids, in addition to the chromosomally mediated SHV-1 beta-lactamase. These nine antimicrobial resistance mechanisms comprised two extended-spectrum beta-lactamases (ESBLs) (PER-2 and CTX-M-2), TEM-1-like, OXA-9-like, AAC(3)-IIa, AAC(6')-Ib, ANT(3")-Ia and resistance determinants to tetracycline and chloramphenicol. During fluoroquinolone treatment, a variant derived from M1803 (named M1826) was selected, with an overall increase of MICs, in particular of cefoxitin and carbapenems. No enzymic activity against these latter drugs was found. Mutations in the region analogous to the quinolone resistance-determining region were not found. Strain M1826 was deficient in OmpK35/36 expression, which produced the decrease in the susceptibility to cefoxitin, carbapenems and fluoroquinolones. The blaCTX-M-2 gene was located in an unusual class 1 integron, which includes Orf513, as occurred in the recently described In35. In addition, Tn3 and Tn1331 were detected in both K. pneumoniae isolates. This is the first report of in vivo selection of an OmpK35/36 deficiency in a K. pneumoniae strain that produced a novel combination of two ESBLs (CTX-M-2 and PER-2) during fluoroquinolone treatment in a paediatric patient with chronic urinary infection.     

Activity of weekly irinotecan (CPT-11) in patients with advanced non-small cell lung cancer pretreated with platinum and taxanes

Irinotecan (CPT-11), a semisynthetic derivative of camptothecin, is active in the treatment of non-small cell lung cancer (NSCLC). In this report we describe our experience with this drug when used as a single agent in patients with advanced NSCLC refractory to chemotherapy with platinum and taxanes. Nineteen NSCLC patients (thirteen males and six females; 53% adenocarcinoma and 26% squamous cell carcinoma) with a median age of 52 years (range 34–71) and a Karnofsky performance status of 60% (60–80%) were included in the study. At baseline, the patients had a median of two disease sites and had been treated with a median of two prior regimens. Irinotecan was given at a dose of 100mg/m² i.v.) weekly for 4 weeks followed by 1 week of rest. A total of 123 weekly infusions were administered, and each patient received a median of 4 weeks of treatment (range 1–32). All patients were evaluated by intention-to-treat analysis for efficacy and safety. Main toxicities reported were grade 3 neutropenia (10% of patients), diarrhea (10% of patients), and grade 4 thrombocytopenia (5% of patients). The overall clinical response rate was 16% (95% CI: 8–24) with three partial responses and 9 (47%) patients with stable disease. The median time to progression and the median survival time were 7 and 15 weeks, respectively. In conclusion, weekly irinotecan showed antitumoral activity and minimum toxicity in NSCLC patients refractory to platinum and taxanes.     

Classical and nonclassical 21-hydroxylase deficiency: a molecular study of Argentine patients

OBJECTIVE: To characterize the molecular basis of the 21-hydroxylase deficiency in a group of Argentine patients presenting the classical and nonclassical forms of the disease. DESIGN: To analyse the frequency of point mutations in the CYP21 gene by DNA amplification and mutation detection. PATIENTS: Forty-one patients from 36 nonrelated families: 25 nonclassical (NC), 11 salt-wasting (SW) and five simple virilizing (SV). A total of 27 parents and 13 nonaffected siblings were also analysed. MEASUREMENTS: Basal steroid hormones and 17-hydroxyprogesterone levels following adrenal stimulation with adrenocorticotrophic hormone were measured, together with an analysis of 10 point mutations in the CYP21 gene. RESULTS: A total of 83% and 74.4% classical and nonclassical chromosomes, respectively, were characterized. The intron 2 mutation was the most prevalent among classical alleles. In addition, a high frequency for R356W was observed in both groups (13.3 and 6.9%, respectively), while V281L was the most frequent mutation among the nonclassical patients with a frequency of 39.5%. No alleles containing P30L were observed, and one de novo mutation (R356W) was found. A total of 68.3% patients were fully genotyped, and all but one showed no genotype/phenotype discrepancy. Though the cut-off value for post-ACTH 17-hydroxyprogesterone stimulation was 30.25 nmol/l (10.00 microg/l), the lowest value observed in the fully genotyped nonclassical group was 42.35 nmol/l (14.00 microg/l). CONCLUSIONS: The high number of unidentified alleles in the nonclassical group suggests that less frequent mutations, or the presence of new ones, might be the cause of the disease in the Argentine population. Alternatively, the cut-off value in the ACTH-stimulated 17-hydroxyprogesterone test might overestimate the diagnosis of the nonclassical form by including some patients with heterozygous status.     

Interaction of nitric oxide with calcium in the mesenteric bed of bile duct-ligated rats

We have analysed the interaction of NO with calcium in order to study the molecular mechanisms responsible for the vascular hyporesponse of liver cirrhosis. The experiments have been performed in the isolated and perfused mesenteric arterial bed of rats with bile duct ligation (BDL) and their controls. While perfusing the vessels with normal Krebs, methoxamine (MTX) or KCl produced a lower pressor response in the BDL mesenteries. The NO synthesis inhibitor N(w)-nitro-L-arginine (NNA) potentiated those responses and abolished the differences between groups. The administration of MTX under perfusion with zero calcium-Krebs, to analyse the intracellular release of calcium, also induced a lower response in the BDL mesenteries and NNA potentiated and normalized the response. To investigate calcium entry, the vessels were perfused with zero-calcium Krebs containing high potassium to open voltage-dependent calcium channels. Then, the addition of calcium (10(-1) - 3 x 10(-3) M) produced a lower pressor response in the BDL vessels, that was corrected by NNA. To study calcium entry through receptor-operated channels, the vessels were perfused with zero-calcium Krebs containing MTX. The addition of calcium elevated the perfusion pressure less in the BDL mesenteries than in the control and NNA potentiated the responses and eliminated the between groups differences. When calcium entry through both voltage- and receptor-operated channels was simultaneously analysed, similar results were obtained. In the mesenteric bed of bile duct ligated rats, an excess of nitric oxide affects vascular calcium regulation through an interaction with both calcium entry and intracellular calcium release.     

Palliative care in advanced cancer. A 7-year experience at the Dr. Juan I. Menchaca Civil Hospital of Guadalajara,Jalisco, Mexico

We describe 7 years of experience in terminal cancer care provided by a multi-professional palliative care team. A total of 995 persons requested our services during this period. We included 649 patients for whom we had sufficient information for this study. Average age was 58 years; 60.2% patients were female, whereas 39.7% were male. Underlying disease was cervical cancer followed by breast cancer and prostate, etc. The most frequent symptom on admission was pain followed by weakness, loss of weight, anorexia, and emesis (nausea and vomiting). Average stay in the program of patients who died (406) was 67 days with a range of 1-707 days. We compare symptom incidence and model of care with other palliative care and hospice programs in the world. Cost-Benefit and future implementation of similar programs in Mexico is discussed.     

NK cell activity in tuberculosis is associated with impaired CD11a and ICAM-1 expression: a regulatory role of monocytes in NK activation

Although the role of natural killer (NK) cells in mycobacterial infections is unclear, it has been postulated that they contribute to protective immunity through the production of interferon (IFN)-gamma. In this study, we evaluate the effect of interleukin (IL)-10, IL-15 and IL-18 on NK lytic activity through the expression of CD16, CD11a and CD69 molecules and the induction of IFN-gamma production in patients with tuberculosis (TB) and healthy individuals (N). Our results showed an impairment of NK lytic activity and a gradual down-regulation of costimulatory and adhesion molecules on NK cells which were dependent on the severity of the disease. NK lytic activity was increased by exogenous IL-15 and IL-18 in both TB and N, and by neutralization of endogenous IL-10 only in TB; IL-15 and IL-18 increased CD69 receptor expression, while anti-IL-10 up-regulated CD16 and CD11a expression in TB. Mycobacterium tuberculosis reduced the number of intracellular adhesion molecule (ICAM)-1(+) CD14(+) cells, but in the presence of IL-15, IL-18 and anti-IL-10 its expression was up-regulated. In cells from TB patients, the observed effects of IL-15 and IL-18 on NK function were not dependent on IL-10 modulation of the surface expression of activator/adhesion molecules. In the absence of monocytes, IL-10 activated NK cells, suggesting an indirect effect on their function. Furthermore, in TB patients the depletion of monocytes increased the production of IFN-gamma by NK cells. Therefore, monocytes from TB patients regulated the NK function involving IL-10 which, through an indirect mechanism, led to the down-regulation of costimulatory/adhesion molecules and/or IFN-gamma production.     

Sustained exposure to bacterial antigen induces interferon-gamma-dependent T cell receptor zeta down-regulation and impaired T cell function

T cell antigen receptor zeta chain down-regulation and impaired in vitro T cell function have been described in cancer and autoimmune and infectious diseases. However, the immunological basis for this phenomenon is unknown. Sustained exposure to antigen and chronic systemic inflammation, factors shared by the various pathologies, might account for this phenomenon. We developed an in vivo experimental system that mimics these conditions and show that sustained exposure of mice to bacterial antigens was sufficient to induce T cell antigen receptor zeta chain down-regulation and impair T cell function, provided an interferon-gamma-dependent T helper type 1 immune response developed. This indicates zeta chain down-regulation could be a physiological response that attenuates an exacerbated immune response. However, it can act as a 'double-edged sword', impairing immune responses to chronic diseases.     

Blunt trauma in kidney transplant with preservation of renal function

A 35-year-old male received a living related kidney transplant. At 184 months posttransplantation he suffered a direct right iliac fossa blunt trauma while working on a machine in a steel factory. Graft pain, dysuria and gross hematuria were observed and CT showed a periallograft hematoma. Because of his anemia and graft function deterioration, surgical exploration was warranted. A 500-cc perigraft hematoma was compressing the kidney and ureter, a 5-cm long, 5-mm in depth linear laceration in the lateral aspect of the superior pole of the graft and a 15-mm long, 2-mm in depth linear laceration in the medial aspect of the superior pole were actively bleeding. Major renal arteries and veins were not injured. Both lacerations were closed by suturing the renal parenchyma over gelfoam pledgets with absorbable suture in a buttress fashion. The kidney was salvaged. Serum creatinine was maintained at 1.5 mg/dl during follow-up. A review of the literature showed that few cases of traumatic renal graft rupture with kidney salvage have been reported. Our case is one of them.