Invasive Haemophilus influenzae disease in adults.

In a five-year period, 29 cases of bacteremia and/or meningitis in adults caused by Haemophilus influenzae were seen in our large community hospital. There were 17 cases of bacteremic pneumonia and 12 cases of serious extrapulmonary infections. The extrapulmonary infections included cases of endocarditis, meningitis, cholecystitis, epiglottitis, tubo-ovarian abscess, and cellulitis. In contrast with the pediatric experience, H influenzae type B was the causative pathogen in only 45% of patients and only one isolate was ampicillin resistant.

Therapy of Mycobacterium marinum infections. Use of tetracyclines vs rifampin.

We describe four patients with Mycobacterium marinum infections who did not respond to two- to six-week courses of therapy with tetracycline, minocycline, and doxycycline. All four patients had prompt responses to therapy with either rifampin alone (two patients) or rifampin in combination with ethambutol. Results of antimicrobial sensitivity tests may be helpful in guiding therapy. Rifampin may be the drug of choice for treatment of these infections.

Immunization with high-dose intradermal recombinant hepatitis B vaccine in healthcare workers who failed to respond to intramuscular vaccination.

OBJECTIVE: To achieve immunity to hepatitis B in healthcare workers who failed to respond to intramuscular vaccination and boosters. DESIGN: An open prospective study of intradermal vaccination with recombinant hepatitis B vaccine. SETTING: A large community hospital in Connecticut. PARTICIPANTS: Healthcare workers including physicians, nurses, and laboratory workers. RESULTS: Immunization with high-dose intradermal recombinant hepatitis B vaccine, given in up to four doses, achieved immunity in 88% of healthcare workers who had previously been nonimmune. CONCLUSIONS: We conclude that intradermal vaccination is efficacious in the majority of healthcare workers who failed to respond to intramuscular vaccine. Further studies, including randomized comparisons with intramuscular vaccine as well as studies of cell-mediated immunity, appear warranted.

Seroprevalence of antibodies to hepatitis C virus in high-risk hospital personnel.

OBJECTIVE: To estimate seroprevalence of antibodies to hepatitis C virus in healthcare workers at high risk for blood exposure. DESIGN: A prospective anonymous seroprevalence survey of 243 healthcare workers. SETTING: A large referral hospital and 2 community hospitals in Connecticut. PARTICIPANTS: Healthcare workers, including surgical personnel, dentists, hemodialysis workers, laboratory workers, and emergency room staff. RESULTS: Antibody to hepatitis C virus was found in 1.6% (95% confidence interval [CI95] = 0-3.2%) of healthcare workers. None of the prevalent seropositives had a past history of clinical hepatitis or blood transfusion. CONCLUSIONS: We conclude that the seroprevalence of hepatitis C virus in healthcare workers with a high degree of blood exposure is low and is similar to seroprevalence rates reported for volunteer blood donors. However, first-generation hepatitis C serologic tests may underestimate the true prevalence of infection. Further studies, including prospective cohort studies, will be required to determine if the low seroprevalence is from low risk of acquisition of disease or from loss of measurable humoral antibody response to the virus.

Native-valve endocarditis caused by Staphylococcus epidermidis. A histologically confirmed case.

Staphylococcus epidermidis is among the most common organisms isolated from blood cultures. Conversely, it is rarely a well-documented cause of natural-valve endocarditis. However, several authors have reported series of patients with the clinical picture of endocarditis and S. epidermidis bacteremia. Most of these cases have not been confirmed by examination of the valve. The authors present a case of natural-valve endocarditis caused by S. epidermidis with pathologic documentation of the offending agent.

Herpes simplex encephalitis: a review.

Patients with herpes simplex encephalitis generally have altered mental function and are rarely able to provide a good medical history. Failure to diagnose this serious disease may result in permanent neurologic damage or death of the patient. Rapid institution of newer diagnostic tests such as polymerase chain reaction for herpes simplex virus is essential for proper diagnosis. Parenteral acyclovir therapy is efficacious but, clearly, improvements in prevention and therapy are still important research goals. This review is meant to inform physicians and nurses concerning the current diagnosis and management of this treatable but potentially fatal illness.

Clinical manifestations and antibiotic treatment of Lyme disease.

As the incidence of Lyme disease increases in Connecticut and world-wide, considerable attention has been given to its prompt diagnosis and treatment. Creating further interest in this infection is the awareness that inappropriate therapy may result in significant disabling sequelae many years later. In this review, we focus mainly on current treatment options, but stress that the recommendations may change appreciably, as more information appears on the efficacy of new antibiotics.

Construction of a Synechocystis PCC6803 mutant suitable for the study of variant hexadecameric ribulose bisphosphate carboxylase/oxygenase enzymes.

The cyanobacterium Synechocystis PCC6803 was chosen as a target organism for construction of a suitable photosynthetic host to enable selection of variant plant-like ribulose bisphosphate carboxylase/oxygenase (Rubisco) enzymes. The DNA region containing the operon encoding Rubisco (rbc) was cloned, sequenced and used for the construction of a transformation vector bearing flanking sequences to the rbc genes. This vector was utilized for the construction of a cyanobacterial rbc null mutant in which the entire sequence comprising both rbc genes, was replaced by the Rhodospirillum rubrum rbcL gene linked to a chloramphenicol resistance gene. Chloramphenicol-resistant colonies, Syn6803 delta rbc, were detected within 8 days when grown under 5% CO2 in air. These transformants were unable to grow in air (0.03% CO2). Analysis of their genome and Rubisco protein confirmed the site of the mutation at the rbc locus, and indicated that the mutation had segregated throughout all of the chromosome copies, consequently producing only the bacterial type of the enzyme. In addition, no carboxysome structures could be detected in the new mutant. Successful restoration of the wild-type rbc locus, using vectors bearing the rbc operon flanked by additional sequences at both termini, could only be achieved upon incubating the transformed cells under 5% CO2 in air prior to their transferring to air. The yield of restored transformants was proportionally related to the length of those sequences flanking the rbc operon which participate in the homologous recombination. The Syn6803 delta rbc mutant is amenable for the introduction of in vitro mutagenized rbc genes into the rbc locus, aiming at the genetic modification of the hexadecameric type Rubisco.

Bacteriophage T4 anticodon nuclease, polynucleotide kinase and RNA ligase reprocess the host lysine tRNA.

Host tRNAs cleaved near the anticodon occur specifically in T4-infected Escherichia coli prr strains which restrict polynucleotide kinase (pnk) or RNA ligase (rli) phage mutants. The cleavage products are transient with wt but accumulate in pnk- or rli- infections, implicating the affected enzymes in repair of the damaged tRNAs. Their roles in the pathway were elucidated by comparing the mutant infection intermediates with intact tRNA counterparts before or late in wt infection. Thus, the T4-induced anticodon nuclease cleaves lysine tRNA 5' to the wobble position, yielding 2':3'-P greater than and 5'-OH termini. Polynucleotide kinase converts them into a 3'-OH and 5' P pair joined in turn by RNA ligase. Presumably, lysine tRNA depletion, in the absence of polynucleotide kinase and RNA ligase mediated repair, underlies prr restriction. However, the nuclease, kinase and ligase may benefit T4 directly, by adapting levels or decoding specificities of host tRNAs to T4 codon usage.

HIV-1 integrase blocks infection of bacteria by single-stranded DNA and RNA bacteriophages.

Expression of human immunodeficiency virus-1 integrase in Escherichia coli, at levels that had no effect on bacterial cell growth, blocked plaque formation by bacteriophages having single-stranded genomic DNA (M13) or RNA (R17, Q beta, PRR1). Plaque formation by phages having double-stranded genomic DNA (T4, PR4) was unaffected. Integrase also inhibited infection by the phagemid M13KO7, but it had no effect on production of phage once infection by M13KO7 was established. This result indicated that integrase affects an early stage in infection. Integrase also inhibited phage production following transfection by either single-stranded or double-stranded (replicative form) M13 DNA, it blocked M13 DNA replication, as assayed by incorporation of radioactive nucleotides into DNA, and it failed to affect bacterial pilus function. These data suggest that integrase interacts in vivo with phage nucleic acid, a conclusion supported by studies in which integrase was shown to have a DNA-binding activity in its C-terminal portion. This portion of integrase was both necessary and sufficient for interference of plaque formation by M13 in the present study. Expression of the N-terminal portion of integrase at the same level as intact integrase had little effect on phage growth, indicating that expression of foreign protein in general was not responsible for the inhibitory effect. The simple bacteriophage assay described is potentially useful for identifying integrase mutants that lack single-stranded DNA binding activity.

Complementation tests between alkaline phosphatase-constitutive mutants (phoS and phoT) of Escherichia coli.

Complementation tests between phoS and phoT mutations showed that they belong to the same cistron. Homozygosis of a heterozygotic partial diploid resulted from allelic transfer from the chromosome to the F' episome.

Trimethoprim-sulfamethoxazole for bacterial meningitis.

Trimethoprim-sulfamethoxazole has excellent microbiologic activity against most pathogens that produce meningitis; both components of this drug have high penetration into tissues, including the cerebrospinal fluid. Clinical experience shows that trimethoprim-sulfamethoxazole may be beneficial in the treatment of gram-negative bacillary meningitis caused by organisms only moderately susceptible to third-generation cephalosporins (Enterobacter cloacae, Serratia marcescens) or resistant to these antibiotic agents (Pseudomonas cepacia, Acinetobacter). The success of trimethoprim-sulfamethoxazole in the treatment of four patients with Staphylococcus aureus and two patients with Listeria monocytogenes meningitis shows that this drug may also be useful in treating infrequent types of gram-positive meningitis.

Isolation and properties of Escherichia coli K-12 mutants impaired in the utilization of gamma-aminobutyrate.

We have isolated mutants of Escherichia coli K-12 CS101B that have lost the ability to utilize gamma-aminobutyrate as a source of nitrogen. One class of mutants, which were not affected in the utilization of other nitrogen sources (proline, arginine, glycine), included many isolates with lesions in gamma-aminobutyrate transport or in its transamination and one mutant completely devoid of succinic semialdehyde dehydrogenase activity and exhibiting low gamma-aminobutyrate transport and transamination. gamma-Aminobutyrate-utilizing revertants of the latter recovered full transport and transamination capacities but remained dehydrogenaseless. Another class of mutants showed pleiotropic defects in nitrogen metabolism. One such mutant was lacking glutamate synthase activity. The genes specifying the synthesis of gamma-aminobutyrate permease, gabP, gamma-aminobutyrate transaminase, gabT, and succinic semialdehyde dehydrogenase, gabD, and the control gene, gabC, that coordinately regulates their expression all form a cluster on the E. coli chromosome, linked to the srl and recA loci (at 57.5 min). The mutations with pleiotropic effects on the metabolism of nitrogenous compounds are not linked to the gab cluster.

Potential role of trimethoprim-sulfamethoxazole in the treatment of serious hospital-acquired bacterial infections.

Although trimethoprim-sulfamethoxazole (TMP-SMZ) has become a standard agent for the treatment of a broad range of infections, it may often be overlooked as a choice for treatment of serious hospital-acquired infections. A review of the literature shows that a number of common and uncommon gram-negative and gram-positive organisms susceptible to TMP-SMZ are frequently resistant to cephalosporins. TMP-SMZ has, in addition to its exceptional microbiologic activity, pharmacokinetic characteristics that make it a potentially cost-effective alternative to third-generation cephalosporins in the treatment of serious hospital-acquired infections caused by susceptible organisms.

Gastroenteritis, sepsis, and osteomyelitis caused by Plesiomonas shigelloides in an immunocompetent host: case report and review of the literature.

We report the 11th human case of bloodstream infection with Plesiomonas shigelloides. This was the first case without any apparent underlying immunocompromising disease, and the patient was the first adult to survive the infection. We review all the extraintestinal cases associated with this organism, giving special attention to the clinical characteristics of the bloodstream infections reported previously.

Specificity and regulation of gamma-aminobutyrate transport in Escherichia coli.

A specific gamma-aminobutyrate (GABA) transport system in Escherichia coli K-12 cells with a K(m) of 12 muM and a V(max) of 278 nmol/ml of intracellular water per min is described. Membrane vesicles contained d-lactate-dependent activity of the system. Mutants defective in GABA transport were isolated; they lost the ability to utilize GABA as a nitrogen source, although the activities of glutamate-succinylsemialdehyde transaminase (GSST) (EC 2.6.1.19) and succinylsemialdehyde dehydrogenase (SSDH) (EC 1.2.1.16), the enzymes that catalyze GABA utilization, remained as high as in the parental CS101B strain. The ability to utilize l-ornithine, l-arginine, putrescine, l-proline, and glycine as a nitrogen source was preserved in the mutants. The genetic lesions resulting in the loss of GABA transport, gabP5 and gabP9, mapped in the gab gene cluster in close linkage to gabT and gabD, the structural genes of GSST and SSDH, and to gabC, a gene controlling the utilization of GABA, arginine, putrescine, and ornithine. The synthesis of the GABA transport carrier is subject to dual physiological control by (i) catabolite repression and (ii) nitrogen availability. Experiments with glutamine synthetase (EC 6.3.1.2)-negative and with glutamine synthetase-constitutive strains strongly indicate that this enzyme is the effector in the regulation of GABA carrier synthesis by route (ii).