Propionibacterium acnes: an under-appreciated cause of post-neurosurgical infection

BACKGROUND

Propionibacterium acnes is increasingly recognized as a cause of post-neurosurgical infection. This review of patients with P. acnes neurosurgical infection was carried out in order to determine clinical characteristics and outcomes in relation to duration of antimicrobial treatment.

METHODS

We retrospectively reviewed the charts of consecutive patients with P. acnes isolated from neurosurgical specimens from 1 January 1999 to 30 June 2005. We defined P. acnes neurosurgical infection as isolation of P. acnes alone from a sterile neurosurgical site in a patient who clinically improved following treatment with an appropriate antibiotic.

RESULTS

We identified 28 patients with definite P. acnes neurosurgical infection; median age 49 years (range 23-77); 15 (54%) male. All patients had prior neurosurgical procedures: 27 (96%) post-craniotomy. The median time from surgery to presentation was 54 days (range 12-1,578). Eighteen out of 28 (64%) patients who met the definition of neurosurgical infection had Gram-positive bacilli seen in at least one surgical specimen compared with only 2/56 (4%) patients who did not meet the definition (P < 0.0001). Intravenous benzyl penicillin +/- oral penicillin VK was the most common treatment. The median duration of antibiotic treatment for intracranial infection was 29 days. Five of nine patients who had extracranial bone-flap-associated infection had <or=7 days of intravenous treatment and were cured. Two patients had relapse or reinfection.

CONCLUSIONS

P. acnes neurosurgical infection often presents in an indolent fashion. Gram-positive bacilli on Gram stain should not be discounted as a contaminant in neurosurgical specimens. Associated bone flaps should be removed. Intravenous benzyl penicillin +/- oral penicillin VK remains effective treatment.

What do specialist registrars know about clinical governance?

Clinical governance is an essential part of quality assurance for everyday clinical practice. It is part of the generic curriculum for all specialist registrars (SpRs) training in medical specialities. The authors of this update undertook a survey of SpRs training in geriatric medicine to determine their perceived knowledge of clinical governance and whether they had received training in this area.

Short course intravenous benzylpenicillin treatment of adults with meningococcal disease

BACKGROUND

Short-course treatment of meningococcal disease (including meningitis) with 4-5 days of an i.v. beta-lactam is of proven efficacy. Since April 1998, all adult patients with meningococcal disease admitted to Auckland Hospital were prospectively treated with 3 days of i.v. benzylpenicillin.

AIMS

To assess the clinical features, laboratory findings, disease complications and outcome of patients with meningococcal disease prospectively treated with 3 days of i.v. benzylpenicillin.

METHODS

A retrospective chart review of all adult patients with meningococcal disease admitted to Auckland Hospital from April 1998 to December 2002 was conducted.

RESULTS

Ninety patients with definite (n = 72) or -probable (n = 16) meningococcal disease were admitted during the study period. Two were excluded on the basis of treatment duration. The remaining 88 patients received a mean +/- standard deviation duration of treatment of 3.1 +/- 0.5 days (excluding those who died while receiving treatment). Six patients (7%) died, four of whom while on treatment. There were no relapses.

CONCLUSION

Three days of i.v. benzylpenicillin for the treatment of adults with meningococcal disease is effective.

Determining the relationship between end-of-life decisions expressed in advance directives and resuscitation efforts during cardiopulmonary resuscitation

In recent years, there has been an increased focus on end-of-life decisions and the use of medical technology. It is not well documented in the literature whether or not and to what extent patients' advance directives are used for directing resuscitative efforts. The purpose of this study was to determine how useful patients' advance directives were to members of the health care team in determining treatment and end-of-life decisions among patients who received cardiopulmonary resuscitation (CPR) efforts. Medical records of 135 adult patients who had undergone CPR efforts within the previous year were reviewed to determine if and to what extent advance directives were useful in directing end-of-life care and treatment decisions. Only 35 of these patients had advance directives. Three categories for advance directives emerged: those that were "independently directive," those that were "vague and required further clarification," and those that were "nondirective." Information from this study may be used to clarify treatment options for end-of-life care and to determine if and what further interventions are required to ensure that advance directives can be executed as meaningful documents.

Structure-based design of potent, amidine-derived inhibitors of factor Xa: evaluation of selectivity, anticoagulant activity, and antithrombotic activity

To enhance the potency of 1,2-dibenzamidobenzene-derived inhibitors of factor Xa (fXa), an amidine substituent was incorporated on one of the benzoyl side chains to interact with Asp189 in the S1 specificity pocket. Lead molecule 1 was docked into the active site of fXa to facilitate inhibitor design. Subsequently, iterative SAR studies and molecular modeling led to a 1000-fold increase in fXa affinity and a refined model of the new inhibitors in the fXa active site. Strong support for the computational model was achieved through the acquisition of an X-ray crystal structure using thrombin as a surrogate protein. The amidines in this series show high levels of selectivity for the inhibition of fXa relative to other trypsin-like serine proteases. Furthermore, the fXa affinity of compounds in this series (K(ass) = 50-500 x 10(6) L/mol) translates effectively into both anticoagulant activity in vitro and antithrombotic activity in vivo.

Experimental inoculation of avian polyomavirus in chemically and virally immunosuppressed chickens

The purpose of this series of experiments was to determine the effect of various types of immunosuppressive treatments (cyclophosphamide, infectious bursal disease virus [IBDV], chicken anemia virus [CAV], and combination infection with IBDV and CAV) on susceptibility of chickens to challenge with avian polyomavirus. In the first experiment, chickens were chemically bursectomized with intraperitoneal injections of cyclophosphamide; in the second study, chickens were orally inoculated with IBDV; in the third study, birds were intramuscularly inoculated with CAV; and in the final study, birds were inoculated with both IBDV and CAV. In all experiments, chickens were challenged with 10(4.7) tissue culture infective doses of polyomavirus intraperitoneally. Only chemically bursectomized chickens developed lesions similar to those found in the naturally occurring multisystemic fatal form of polyomavirus infection seen in psittacine nestlings, including hepatic necrosis and large pale intranuclear inclusions.

Acute idiopathic gastric dilation with gastric necrosis in individuals with Prader-Willi syndrome

Individuals with Prader-Willi syndrome (PWS) have excessive appetite with the ability to consume large quantities of food. Absence of vomiting and a high pain threshold are considered manifestations of the disorder. We present 6 patients with PWS with acute dramatic gastric distention. In 3 young adult women with vomiting and apparent gastroenteritis, clinical course progressed rapidly to massive gastric dilatation with subsequent gastric necrosis. One individual died of overwhelming sepsis and disseminated intravascular coagulation. In 2 children, gastric dilatation resolved spontaneously. Gastrectomy specimens--in 2 cases subtotal and distal, in the other with accompanying partial duodenectomy and pancreatectomy--showed similar changes. All cases demonstrated signs of ischaemic gastroenteritis. All specimens showed diffuse mucosal infarction with multifocal transmural necrosis. Vascular dilatation and small bifrin thrombi were apparent within the infarcted areas. These 6 women with PWS had acute idiopathic gastric dilatation. It is possible that a predisposition to acute gastric dilatation may be related to abnormal gastric homeostasis on a genetic basis. Understanding the mechanisms responsible for this event could increase the understanding of gastrointestinal and appetite regulation in individuals with PWS.

Exercise intensity dependent inhibition of 1-methyl-1-nitrosourea induced mammary carcinogenesis in female F-344 rats

The objective of this experiment was to evaluate the effects of treadmill exercise on tumor induction in an experimental model for breast cancer. Female F-344 rats were injected i.p. with 50 mg MNU/kg body wt at 50 and 57 days of age. Animals were assigned to one of five groups: sham exercise or 35% or 70% maximal treadmill running intensity for 20 or 40 min/day, 5 days per week. These work rates represent an exercise intensity level generally considered insufficient to improve cardiovascular fitness (35% maximal intensity) or an aerobic level of exercise sufficient to improve cardiovascular fitness in humans (70% maximal intensity). Rats were exercised for 3 months following carcinogen administration at which time the experiment was terminated. Mammary cancer incidence was reduced by as much as 37% and cancer multiplicity by < 60% at the highest exercise intensity. Unexpectedly, the degree of protection against cancer was proportional to the intensity but not to the duration of exercise.

Two SH2 domains of p120 Ras GTPase-activating protein bind synergistically to tyrosine phosphorylated p190 Rho GTPase-activating protein

p120 GTPase-activating protein (GAP) is a negative regulator of Ras that functions at a key relay point in signal transduction pathways that control cell proliferation. Among other proteins, p120 GAP associates with p190, a GAP for the Ras-related protein, Rho. To characterize the p120.p190 interaction further, we used bacterially expressed glutathione S-transferase fusion polypeptides to map the regions of p120 necessary for its interactions with p190. Our results show that both the N-terminal and the C-terminal SH2 domains of p120 are individually capable of binding p190 expressed in a baculovirus/insect cell system. Moreover, the two SH2 domains together on one polypeptide bind synergistically to p190, and this interaction is dependent on tyrosine phosphorylation of p190. In addition, mutation of the highly conserved Arg residues in the critical FLVR sequences of both SH2 domains of full-length p120 reduces binding to tyrosine-phosphorylated p190. The dependence on p190 phosphorylation for complex formation with p120 SH2 domains observed in vitro is consistent with analysis of the native p120.p190 complexes formed in vivo. These findings suggest that SH2-phosphotyrosine interaction is one mechanism by which the cell regulates p120.p190 association and thus may be a means for coordinating the Ras- and Rho-mediated signaling pathways.

Construction of a reshaped HMFG1 antibody and comparison of its fine specificity with that of the parent mouse antibody

A human antibody with milk mucin specificity was obtained by transferring the complementarity determining regions (CDR) of the mouse antibody HMFG1 onto carefully selected human framework regions. The resulting reshaped human antibody, HuHMFG1, showed no difference in relative affinity for its antigen compared with the parent mouse HMFG1. The minimum epitope recognized by both the mouse and reshaped antibodies was demonstrated by epitope mapping to be identical, and consists of the tetramer PDTR. In a replacement net analysis, in which each of the amino acids was replaced in turn with the 19 other residues, it was determined that mouse HMFG1 and HuHMFG1 reacted with this series of synthetic peptides in an equivalent manner, indicating retention of identical fine specificity in the HuHMFG1 antibody. In contrast to other published reports, this was achieved without involvement of any framework residues in the binding site transfer. These data demonstrate that if well-matching human framework regions are employed grafting the CDR only can be sufficient to confer desired specificities to human antibodies and can, indeed, provide human analogues of mouse antibodies with virtually indistinguishable affinities and fine specificities relative to the mouse parent antibodies.

Alkaline elution analysis of DNA fragmentation induced during apoptosis

We report that alkaline elution analysis fails to provide a complete profile of DNA fragmentation induced by some genotoxic agents, particularly if these agents induce apoptotic cell death resulting in fragmentation of DNA into oligonucleosomal length multimers. It was questioned whether these oligonucleosome fragments are responsible for the more rapidly eluting component of DNA that is observed as a biphasic elution profile when cells treated with certain genotoxic agents are subjected to alkaline elution. The results of this study indicate that DNA fragmented during apoptotic cell death is eluted in fractions before alkaline denaturation that are normally discarded. Collection of fractions prior to alkaline denaturation is recommended for complete evaluation of the total spectrum of damage induced by genotoxic agents, especially when the compound is suspected of inducing cell death by apoptosis.