A case of mistaken identity? Vaccinia virus in a live camelpox vaccine.

Live-attenuated (LA), and inactivated adjuvant (IA) camelpox virus (CMLV) vaccines are produced in several countries worldwide. A tissue culture attenuated CMLV isolated (Jouf-78) is used to produce an LA vaccine in Saudi Arabia (Hafez et al., 1992). DNA extracts from the Saudi LA vaccine were used as positive controls for a routine ATIP PCR produced fragments longer than 881 bp. PCR-amplified ATIP sequences were similar to vaccinia virus (VACV) Lister strain. PCR and sequence analysis of two extracellular enveloped virus (EEV)-specific (A33R and B5R), and two intracellular mature virus (IMV) (L1R and A27L) othrologue genes from the vaccine DNA extracts confirmed the finding. CMLV sequences were not detected in vaccine DNA extracts. A VACV Lister strain imported from Switzerland was used in control experiments during initial testing of the Saudi LA vaccine. High antigenic similarity between VACV and CMLV, and a possible contamination event during production may have caused this issue. Environmental and health impact studies were recommended because early VACV vaccines produced in some European countries contained nonhighly attenuated strains that were not adequately screened for adventitious agents.

Fluctuation and noise propagation in phenotypic transition cascades of clonal populations.

Quantitative modeling of fluctuations of each phenotype is a crucial step towards a fundamental understanding of noise propagation through various phenotypic transition cascades. The theoretical formulas for noise propagation in various phenotypic transition cascades are derived by using the linear noise approximation of master equation and the logarithmic gain. By virtue of the theoretical formulas, we study the noise propagation in bidirectional and unidirectional phenotypic transition cascades, respectively. It is found that noise propagation in these two phenotypic transition cascades evidently differs: In the bidirectional cascade, a systemic random environment is provided by a correlated global component. The total noise of each phenotype is mainly determined by the intrinsic noise and the transmitted noise from other phenotypes. The intrinsic noise enlarged by interconversion through an added part shows a novel noise propagation mechanism. However, in the unidirectional cascade, the random environment of each downstream phenotype is provided by upstream phenotypes. The total noise of each downstream phenotype is mainly determined by the transmitted noises from upstream phenotypes. The intrinsic noise and the conversion noise can propagate in both bidirectional and unidirectional phenotypic transition cascades.

Sequential emergence of multi-resistant Klebsiella pneumoniae in Bahrain.

During the mid-1980s, nosocomial infections due to aminoglycoside-resistant Klebsiella pneumonia were prevalent in the intensive care unit (ICU) of the Salamanya Medical Centre, Bahrain. In an attempt to control the spread of such organisms, the third-generation cephalosporins were introduced in early 1987. Subsequently there was a marked increase in the incidence of cephalosporin resistance among Klebsiella spp. isolated in the ICU. In 1990, over 60% of Klebsiella isolates were resistant to both cephalosporins and aminoglycosides. Cephalosporin resistance was due to production of extended-spectrum beta-lactamases encoded on the same plasmid as aminoglycoside resistance. The incidence of cephalosporin resistance declined during 1991-1992, which was coincident with severe restrictions on the use of third-generation cephalosporins and the preferential use of ciprofloxacin and imipenem for nosocomial klebsiella infections. Sequential overuse of aminoglycosides and cephalosporins for nosocomial klebsiella infection may select for organisms resistant to both classes of antibiotics.

Recovery and molecular characterization of live Camelpox virus from skin 12 months after onset of clinical signs reveals possible mechanism of virus persistence in herds.

Potentially pathogenic orthopoxviruses (OPVs) persist in nature and re-emerge for reasons we do not fully understand. New information pertaining to Orthopoxvirus (OPV) persistence in nature would significantly improve surveillance and control programs. In a recent investigation of a Camelpox virus (CMLV) outbreak in Eastern Saudi Arabia, atypical minute pox-like skin lesions (AMPL) persisted on 42.9% of convalescent camels (8.8% of herd) for more than a year after the onset of clinical signs. In order to investigate whether AMPL were related to CMLV infection, AMPL homogenates were inoculated on the chorioallantoic membranes (CAM) of specific-pathogen-free (SPF) embryonating chicken eggs (ECE). Live CMLV was recovered from AMPL homogenates. The sequences of the ATIP gene of viruses isolated in the beginning of the outbreak, and one year later from AMPL were identical, and similar to the Kazakhstan isolate CMLV M-96. Virus identity was confirmed by sequence analysis of the CMLV A33R, A27L, B5R, and L1R orthologue genes. Uninfected adult camels that came in contact with animals showing AMPL became infected within two weeks. Since AMPL were easily missed by veterinarians and camel drivers, it was concluded that CMLV survival in persistent skin lesions may be a key mechanism in maintaining the virus in previously infected camel herds during inter-epizootic periods.

Prenatal serologic screening in Bahrain.

Between 1988 and 1990, serological surveys designed to study local disease prevalence and assess the clinical value of various prenatal screening tests were undertaken at Salmaniya Medical Center in Bahrain. High maternal antibody prevalence (greater than 85%) to cytomegalovirus (CMV), herpes simplex virus (HSV) and rubella was demonstrated, and 28% showed antibodies to Toxoplasma gondii. The lowest seroprevalence values were found for HBsAg (1.2%) and Treponema pallidum (0.9%). Routine testing for rubella, syphilis, and hepatitis B are advocated for all pregnancies in Bahrain. In contrast, CMV and HSV serologies are not recommended. Toxoplasma antibody testing remains controversial, but the lack of a proven agent to prevent congenital toxoplasmosis coupled with the high cost of serial testing mitigates against its routine use at this time.

Ciprofloxacin versus ceftriaxone in the treatment of multiresistant typhoid fever.

A randomized trial comparing ceftriaxone (3 g given parenterally per day for 7 days) to ciprofloxacin (500 mg given orally twice a day for 7 days) in the treatment of blood culture positive typhoid fever was conducted. Twenty patients were openly randomized to receive ciprofloxacin and 22 to receive ceftriaxone. The outcome was classified as clinical failure in 6 patients (27%) in the ceftriaxone group, but in none in the ciprofloxacin group (p = 0.01). The mean duration of fever was four days in the ciprofloxacin group and about five days in the ceftriaxone group (p = 0.04). In the six patients in the ceftriaxone group who experienced failure, therapy was switched to ciprofloxacin and the patients became afebrile and asymptomatic within 48 hours. Patients with resistant strains of Salmonella typhi and patients with sensitive strains responded equally well to ciprofloxacin therapy. Analysis of a subset of 12 of the multiresistant strains revealed that resistance was encoded for by a transferable 180 kilobase plasmid. Ciprofloxacin represents a useful treatment option in areas where multiresistant strains are likely to be encountered.