A review of neuropsychiatric adverse events from topical ophthalmic brimonidine.

Brimonidine is a first-line topical medication for increased intraocular pressure and glaucoma which may be used alone or in conjunction with other topical therapies. Its structural and pharmacological comparabilities to clonidine give way to the hypothesis that it may cause neuropsychiatric side effects. The majority of case reports citing brimonidine toxicity, either for topical or peripheral exposure, include pediatric age groups but especially infants. Among the latter, a dose-response phenomenon is evident. Dose-response correlates have also been shown among adults. Case series and prospective double-blind treatment studies also give evidence for the occurrence of several central nervous system adverse reactions. Topical ophthalmic brimonidine use should be followed for the occurrence of neuropsychiatric disturbances generally, and enhanced vigilance should be maintained for at-risk populations.

MRSA and the environment: implications for comprehensive control measures.

Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) is established soon after colonized or infected patients become resident. There are many studies that detail the mechanisms of spread and environmental survival of methicillin-susceptible Staphylococcus aureus (MSSA); this knowledge translates directly into the same findings for MRSA. The potential ubiquity of MRSA in a health-care setting poses challenges for decontamination. Whereas patients and medical staff are important sources for MRSA spread, the environmental burden may contribute significantly in various contexts. Effective control measures must therefore include consideration for MRSA in the environment.

Socks but no gloves.

A 38-year-old female suffered from acute parvovirus B19 infection which was complicated by profound peripheral lower limb edema but no purpuric exanthemata. The pathophysiology of edema in parvovirus infection remains to be accurately defined.

The cranberry and the urinary tract.

Cranberry products have been heralded as natural treatments for urinary tract infections (UTIs) and have been widely used for this purpose. Current evidence favours an antibacterial role for the cranberry's natural polyphenols or tannins. Although limited species- and strain-specific direct inhibition has been determined in vitro, it has been suggested that a key mechanism of inhibition, especially for the abundant uropathogenic E. coli, relies on anti-adhesion properties. Many studies of prevention have been complicated due to the enrollment of patients who have had complicated urinary tracts, and outcomes have not been consistently favourable. In contrast, significant prevention has been shown for acute cystitis among high-risk young females. While reasonably well tolerated and deplete from side effects, further scientific work is required to better place the role of cranberry products in the management of UTIs. Progress in this area has set the stage for further hypothesis testing studies.

Clinical validation for oxacillin susceptibility testing of coagulase negative staphylococci.

Oxacillin susceptibility of coagulase negative staphylococci as assessed by conventional methods was confirmed by a modified Etest method, extended to detect heteroresistance. Verification of susceptibility was followed by successful treatment for six consecutive children with deep seated infections. Physicians' trust in such a validated method will contribute to the appropriate use of antibiotics.

Do mycoplasmas cause human cancer?

A linkage between mycoplasmas and malignancy was mainly proposed in the 1960s when human-associated mycoplasmas were becoming of interest given the novel characterization of the human respiratory pathogen Mycoplasma pneumoniae. Associations with leukemia and other malignancies, however, were largely ascribed to tissue-culture contamination, which is now recognized as a significant potential problem in molecular biology circles. A few epidemiological studies, however, continue to raise concern over such a linkage. As well, in vitro data have demonstrated the potential for some mycoplasmas to induce karyotypic changes and malignant transformation during chronic tissue-culture infestation. As cellular and molecular mechanisms for such transformation become studied, a resurgence of interest in this area is inevitable. A role for mycoplasmas in malignancy of any sort is conjectural, but there remains a need to continue with focussed epidemiological and laboratory investigations.

Utilization of herpes simplex PCR assays for cerebrospinal fluid in a pediatric health care setting.

An assessment was made of the utilization and impact of a diagnostic polymerase chain reaction (PCR) assay for the diagnosis of herpes simplex viruses (HSV) 1 and 2 in cerebrospinal fluid of children who attended a Canadian pediatric referral centre. One hundred and three assays were performed on specimens from 103 patients during the period August 1997 to September 1998. Patient ages ranged from newborn to 16 years. Indications for HSV PCR included seizures with or without fever (56.3%), aseptic meningitis (16.5%), and encephalopathy with or without fever (10.7%). Only 2 of 103 (1.9%) assays were positive, including one each for HSV1 and HSV2. Control specimens that were seeded with virus indicated inhibition for 24.3, 8.8, and 6.8% of assays for HSV1, HSV2, and both HSV1 and HSV2, respectively. The mean turn-around time for HSV PCR was 2.5 days, and 90.3% were completed in less than 5 days. Acyclovir was administered to 78.6% of the patients overall; the results of the HSV PCR impacted on the treatment courses for 36 individuals. Nevertheless, 16.5% of patients continued to receive extended courses of antiviral therapy despite negative HSV PCR assays. Although it is desirable to decrease the frequency of PCR inhibitions and to further decrease the interval to assay completion, HSV PCR does have a significant impact on antiviral use in this setting.

Bartonella henselae infection in British Columbia: evidence for an endemic disease among humans.

Human bartonellosis in North America is mainly associated with Bartonella henselae, and the availability of laboratory diagnostic tools has significantly heightened awareness of the spectrum of human disease that is caused by this bacterium. We detail herein examples of illness in a pediatric population which serve to confirm that B. henselae-associated disease exists in British Columbia. Seroprevalence studies among asymptomatic adults and among children with symptomatic respiratory illness of other causation demonstrated that 36.8% and 18.5% of sera, respectively, had IFA-IgG titres > or = 1:256. IFA-IgG titres did not vary significantly whether B. henselae ATCC 49793 or a local wild-type B. henselae isolate were used as substrate. An assessment of IgM response was consistent with the proposal that endemic seroprevalence is a function of past rather than recent exposure. Both clinical and serological studies are concordant in providing evidence that B. henselae is endemic in British Columbia.

Nosocomial transmission of penicillin-resistant Streptococcus pneumoniae.

Two patients were found to harbor intermediate-level penicillin-resistant Streptococcus pneumoniae in a pediatric hospital setting. For the first patient, the bacterium was isolated from a tracheal aspirate, and for the second patient, a positive blood culture was found a short time after the index case. Two molecular typing techniques (enterobacterial repetitive intergenic consensus sequence polymerase chain reaction, and repetitive sequence-based polymerase chain reaction) demonstrated homology among these isolates, which suggests person-to-person spread. We propose the need for institution-based infection control precautions that will limit the spread of penicillin-resistant pneumococci.

Bacterial genotype and neurological complications of Escherichia coli O157:H7-associated haemolytic uraemic syndrome.

We examined the possibility of an association between the bacterial genotype of Escherichia coli O157:H7 and the likelihood of progression to neurological complications in childhood gastroenteritis-associated haemolytic uraemic syndrome (D+HUS). Bacterial stool isolates were available from 51 patients with HUS; 11 of these patients suffered a neurological complication. Bacteria were assessed for plasmid content, verotoxin (Shiga-like toxin) profile, verotoxin 2 subtype, and presence of the eaeA (effacement and attachment) marker. No association of bacterial genotype with central nervous system (CNS) manifestations was observed. Whilst the cause of CNS manifestations may be multifactorial, there is no evidence at present to implicate specific bacterial traits.

Verification of a PCR-based typing method for Acinetobacter baumannii in a pseudo-outbreak investigation.

Acinetobacter spp. isolates were increasingly obtained from clinical specimens and sterility samples, and a subsequent epidemiological investigation implicated an intermittently contaminated supply of commercially acquired enrichment broths. Typing was performed with DNA amplification by the polymerase chain reaction (PCR) using enterobacterial repetitive intergenic consensus sequence primers, ERIC2 and reverse ERIC1R. The reliability of this PCR-based typing method was verified by the ability of the technique to demonstrate homology and differences among isolates from an epidemiologically well-defined pseudo-outbreak.

Anti-smooth muscle antibody in clinical human and experimental animal Mycoplasma pneumoniae infection.

Autoantibody formation is possibly integral to the development of non-respiratory manifestations of acute Mycoplasma pneumoniae infection. We sought to confirm the occurrence of smooth muscle antibodies (SMA) in humans with acute Myc. pneumoniae respiratory infection and furthermore to assess whether similar autoantibodies would develop in a hamster model of respiratory infection. Paired sera from 21 patients with acute infection were assayed for SMA by immunofluorescence on mouse kidney/stomach substrates. The frequency of SMA was then determined for 52 paediatric patients with acute Myc. pneumoniae infection and 16 controls, and for sera from a hamster model of infection. Five of 21 paired sera had an increment in SMA between acute and convalescent specimens. At a screening dilution of 1:40, 18/52 infected and 0/16 controls had positive sera (P = 0.003); positive specimens demonstrated IgG rather than IgM SMA. In the hamster model of Myc. pneumoniae respiratory infection, significant IgG SMA increases occurred in 7/19 infections but not in 11 controls (P = 0.02). Immunoblotting did not identify actin as the substrate for SMA. Smooth muscle antibody increases are found in a significant minority of Myc. pneumoniae-infected humans and hamsters. A role for SMA in the pathogenesis of Myc. pneumoniae infection remains to be defined.