Identification of non-B human immunodeficiency virus type 1 subtypes in rural Georgia.

As part of an ongoing molecular epidemiological investigation of human immunodeficiency virus type 1 (HIV-1) in rural Georgia, the 5' half of reverse transcriptase (RT) genotypes from 30 patients was sequenced and phylogenetically analyzed. Two patients, GA132 and GA169, were infected with pol sequences of non-B subtype origin that were found to cluster phylogenetically with subtype A-E of Thai origin. Sliding window bootstrap analysis of GA169 showed clear evidence of A/B recombination within the pol gene segment, whereas in the other patient, GA132, no break point within RT could be identified. Interestingly, pairwise comparisons between these 2 patients' C2-V3 env region revealed a 13.5% divergence. However, similar comparisons within the non-B pol segments yielded a 1.23% nucleotide divergence, which suggests a complex phylogenetic and epidemiological history of the subtype A pol genotype in this region. These data demonstrate an increasing diversity of HIV-1 subtypes and the potential emergence of previously unidentified HIV-1 A-E/B recombinants in the rural United States.

Antimicrobial therapy for chronic osteomyelitis in adults: role of the quinolones.

The development of antimicrobial therapy for osteomyelitis is reviewed. The disease, especially when chronic, is notoriously resistant to antibiotic therapy. The duration of disease defining chronicity has decreased considerably in the last 30 years. Successful therapy reflects increased appreciation of the combined roles of surgical debridement and prolonged antimicrobial courses. Parenteral high-dose beta-lactam agents yield clinical success for many patients with chronic osteomyelitis, particularly with prolonged administration and surgical debridement. Over the last decade, the initial success of oral quinolone therapy for gram-negative osteomyelitis was exploited further for staphylococcal diseases. Open clinical trials and comparative trials suggest success rates approximating those achieved with parenteral beta-lactams, particularly with appropriate surgery and adequate duration of therapy. The early results with quinolones and rifampin for prosthesis-related infection are encouraging. Overall, oral quinolones provide a new and frequently proportionate response to a disease that is difficult to treat.

Epidemiology of HIV-1 infection in rural Georgia: demographic trends and analysis at the Medical College of Georgia.

We have conducted a retrospective study of 100 HIV-infected patients enrolled in an AZT monotherapy clinical study at the Medical College of Georgia (MCG) in Augusta, Georgia. When compared to the national trends, our results confirm previous studies that describe an overall increase in the burden of HIV infections among blacks, and, in particular, black women in the rural Southeast. In our cohort, infections due to homosexual contact accounted for approximately 40% of all cases while heterosexual contact and intravenous drug use (IDU) comprised 33% and 13%, respectively. Infections attributable to all other risk factors accounted for the remaining 14%. Relative to national surveillance data, we observed an increase in the prevalence of HIV infections among blacks, and heterosexually acquired infections, particularly among black women. Our analysis illustrates the dynamic nature of the current U.S. epidemic which appears to be shifting both in terms of its demographic and epidemiological profile. These data may indicate that national surveillance data may not reflect the dynamic nature of current demographic trends in HIV incidence, particularly as evidenced in the rural Southeast. This suggests that hospital or laboratory based cross-sectional studies, like ours, that analyze demographic variables of HIV-infected clinic attendees may be necessary to more accurately assess the leading edge of the HIV epidemic in rural, non-metropolitan areas.

Group B streptococcal vertebral osteomyelitis with bacteremia.

Group B streptococcal vertebral osteomyelitis is rare in adults. Osteomyelitis due to this organism is in general related to contiguous infections, recent surgery, or peripheral vascular disease. All reported cases of group B streptococcal vertebral osteomyelitis, however, have had no association with these predisposing factors and have usually been presumed to be of hematogenous origin, though bacteremia has never been demonstrated. Here we describe a 45-year-old intravenous drug abuser who had vertebral osteomyelitis and bacteremia. We conclude that the vertebral osteomyelitis in this patient was hematogenous, as shown by bacteremia, and most likely resulted from intravenous needle use.

The effect of growth temperature on Staphylococcus aureus binding to type I collagen.

Many strains of Staphylococcus aureus produce a collagen-binding surface protein that could enable these strains to colonize tissues such as bone. Previous studies indicated that the expression of the collagen receptor varies with growth conditions. We report here that the growth temperature influences the ability of some S. aureus strains to produce this receptor. S. aureus isolates from human, osteomyelitic bone were grown at 37 degrees C and 42 degrees C and tested for agglutination of collagen-coated latex beads. Binding by 42 degrees C grown cells was significantly reduced in five of the seven isolates studied, including a complete loss of collagen binding in three of these isolates. In an 125I-collagen-binding assay, the binding ability of one of these isolates, strain #16, was 20-fold lower if grown at 42 degrees C. Reduced collagen binding by this isolate could be demonstrated after only two cell divisions at 42 degrees C and the cells regained the ability to bind collagen when shifted back to 37 degrees C. Sodium dodecyl sulfate (SDS)-PAGE confirmed the presence of proteins at 117 kDa in strain #16 and 135 kDa in SMH which were absent following growth at 42 degrees C. Chicken IgG, specific for the 117 kDa protein, was found to react in immunoblot assays with these proteins as well as a protein of 135 kDa extracted from S. aureus Cowan 1. The antibody did not react with proteins extracted from non-binding strains. Strains #15 and #21, collagen-binders at both 37 degrees C and 42 degrees C, produced immunoreactive proteins at 110 and 135 kDa, respectively, in lysates from cells grown at both temperatures. Antibody against a recombinant form of a previously characterized collagen receptor was used to confirm cross-reactivity with these novel collagen receptors. These data suggest that the ability to produce the collagen receptor is temperature sensitive in some S. aureus strains associated with osteomyelitis. It is proposed that a better understanding of the environmental effects on collagen receptor production could enhance our understanding of staphylococcal infections in bone and joints.

Tuberculosis surveillance: lessons from a cluster of skin test conversions.

Mycobacterium tuberculosis has reemerged as a significant public health problem. Elderly persons, especially those in long-term care facilities, are among those at high risk for infection with M. tuberculosis. Frequently, their symptoms are not clearly indicative of M. tuberculosis, and the diagnosis may thus be missed. We discuss the investigation of a cluster of skin test conversions on one locked unit in our long-term care facility. During the epidemiologic investigation, four of 25 patients who had previously had negative results of purified protein derivative testing (16%) and eight of 95 employees (11%) had skin test conversions. Despite a comprehensive, costly evaluation, the index case was not found. We identified weaknesses in our employee and patient M. tuberculosis surveillance programs. Employee baseline purified protein derivative testing data were inadequate. Annual skin tests for employees with previously negative results were not mandatory. There was no mechanism in place to encourage compliance. We developed a plan to educate personnel about the reemergence of M. tuberculosis, signs and symptoms in elderly patients, and the placement and interpretation of purified protein derivative skin tests. Documentation of purified protein derivative surveillance of both patients and employees was computerized. The number of inpatient and outpatient negative-pressure rooms was increased. Appropriate personal protective equipment was made available for use in high-risk situations.

Management considerations for an HIV positive dental student.

Health care workers who are HIV positive or who have AIDS are faced with unique and perplexing problems. Likewise dental students who are HIV positive present a special circumstance that demands review of ethical, legal, managerial, and medical considerations. The purpose of this paper is to describe the management considerations at the Medical College of Georgia following a recent report of an HIV positive dental student. The administration assembled a diverse team of experts for advice in the situation. This group assumed that the circumstance was a potential crisis with possible serious long-term implications. Therefore detailed planning, appropriate announcements, and careful management have been the administration's principle goal for several weeks. The key management strategies and actions are described from the time of notification of the student's HIV antibody test results through the initial testing of the patient population subgroup.

Animal models of osteomyelitis. Knowledge, hypothesis, and speculation.

Each animal model has provided insights. Particularly important was the considerable resistance of bone to infection without manipulation (no morrhuate, fracture, rod, wax, or prosthesis). Such perturbations allow bone infection with much smaller inocula. Typical inocula decreases are 1000 to 10,000 fold. Staphylococci may have a selective advantage in bone because of specialized or tropic binding, perhaps to cartilage or collagen. Osteoclast-induced resorption of hydroxyapatite might explain the distribution of some osteomyelitis. Increased osteoclast activity could link the susceptible metaphyseal regions, the repetitively traumatized diabetic foot, a history of blunt bone trauma, fracture, and perhaps even nearby soft tissue infection. Diagnosis remains difficult; gallium-67 and indium111 labeled WBC probably deserve additional investigation. Therapeutic failures in the rabbit and rat models mirror clinical experience. Clindamycin, rifampin, and quinolones are promising. Neither systemic nor local antimicrobial prophylaxis is well studied yet.

An antibiotic resistant experimental model of Pseudomonas osteomyelitis.

We report a model of chronic Pseudomonas aeruginosa osteomyelitis in the rat that was reproducible, simple and inexpensive. No promoting agent was required to cause infection. Infected animals yielded consistent pseudomonal colony counts (log): 4.98 +/- 0.32 (SD)/g cortical tibia (n = 16). The 95% confidence interval of the mean was 4.83-5.14. The inoculum required to infect 50% of challenged rats (ID50) was log 4.0; the ID 100 was log 6.4. Ceftazidime (50 mg/kg/8 h, subcutaneously), alone and in combination with tobramycin (40 mg/kg/12 h, subcutaneously), produced no significant change in quantitative bacterial count or gross bone pathology when used to treat established disease.

Binding of a Staphylococcus aureus bone pathogen to type I collagen.

We contrasted the collagen-binding potential of the experimental osteomyelitis pathogen, Staphylococcus aureus strain SMH, to several other strains. These included Cowan 1 (binder), Wood 46 (non-binder) and six capsular variants. These measurements were made using an 125I-collagen binding assay. Formalin-killed S. aureus SMH strongly bound commercial type I iodinated collagen (dissociation constant, Kd = 2 x 10(-9) M). The extent of binding was similar to Cowan 1. Binding was saturable and not inhibited by 100 mM solutions of D-glucose, D-galactose, D-mannose, methyl-alpha-L-fucopyranoside, L-hydroxyproline or L-glycine. D-lactose gave moderate inhibition of binding to collagen, and L-fucose was strongly inhibitory. Trypsinized SMH did not bind collagen. None of four Ruthenium-red-staining staphylococci (encapsulated) avidly bound type I collagen. The encapsulated Smith strain, for example, did not bind to collagen but its capsule-negative variant, Smith compact, showed extensive binding. Three of five non-encapsulated S. aureus were strong collagen binders. These data suggest that the prototype bone pathogen binds to the major protein component of bone's extracellular matrix. Collagen-binding is promoted by protein adhesin(s), not capsule. The latter, in fact, appeared to interfere with this interaction. Binding was inhibited by solutions containing the simple monosaccharide, L-fucose.

The promotional effect of bone wax on experimental Staphylococcus aureus osteomyelitis.

The consequences of using surgical bone wax are not well studied. We evaluated the infection-promoting potential of sterile bone wax in a rat model of chronic Staphylococcus aureus osteomyelitis. The addition of bone wax greatly reduced the quantitative bacterial inoculum (log colony-forming units) required to establish chronic osteomyelitis in 50% and 100% of challenged animals. The 50% infection rate was reduced from log 6.9 to 2.6 and the 100% infection rate from 8.2 to 4.4, respectively (p less than 0.015, t test for parallelism). Separate experiments were done 10 to 30 minutes after inoculation with only log 6.4 staphylococci. Tibiae of animals that received bone wax yielded more organisms than those that did not (log 2.76 +/- 0.68 versus 1.72 +/- 0.94, p less than 0.01). At 24 hours quantitative colony counts were not significantly different whether animals received wax or not (log 5.02 +/- 0.42 versus 4.43 +/- 0.65, p greater than 0.09). These studies suggest that the routine surgical use of bone wax should be reassessed.

Treatment of chronic experimental Staphylococcus aureus osteomyelitis with LY146032 and vancomycin.

LY146032 and vancomycin were compared as therapeutic agents in the treatment of chronic Staphylococcus aureus osteomyelitis in the rat. Quantitative cultures disclosed that one of 16, none of 16 and two of 17 tibiae were sterile from the control LY146032, and vancomycin groups, respectively. From positive cultures, geometric mean staphylococcal CFU per gram of bone were as follows: control, 5.13 +/- 1.58; LY146032, 5.36 +/- 0.43 (p = 0.57); and vancomycin, 4.33 +/- 1.73 (p = 0.078). Mean gross pathology was decreased significantly in both treatment groups. LY146032 was no more effective than vancomycin in reducing bacterial counts.

Transmission of human immunodeficiency virus (HIV) by transplantation: clinical aspects and time course analysis of viral antigenemia and antibody production.

The human immunodeficiency virus (HIV) was transmitted to a patient who received a cadaveric renal transplant from a donor who had received massive blood component replacement. A negative HIV antibody test was obtained on serum drawn immediately after transfusion. After transplantation, pretransfusion sera and sera obtained several hours after transfusion tested positive for HIV antibody, suggesting that transfusions had transiently diluted the patient's serum and resulted in a false-negative HIV antibody test. Immediately after transplantation, the recipient showed a transient increase in HIV antigen levels followed by a more sustained increase representing de-novo antigen synthesis. Antibodies to HIV were detected 51 days after transplant. The recipient has shown no signs or symptoms of HIV infection after 1 year. In potential cadaveric organ donors, HIV antibody testing should be performed on pretransfusion sera or on sera obtained several hours after massive transfusion of blood products.

In vivo glycocalyx expression by Staphylococcus aureus phage type 52/52A/80 in S. aureus osteomyelitis.

Osteomyelitic rat tibiae were examined by scanning electron microscopy for the extracellular glycocalyx of Staphylococcus aureus. S. aureus and fractured tibiae from normal rats were incubated together in vitro and examined similarly. Low magnification of endosteal Haversian portals from tibiae studied in vivo and in vitro disclosed adherent S. aureus exuding glycocalyx that buried the organism in dense, coccoid-studded biofilms. The biofilm became progressively more dense over time in vitro and was exuberant at day 70 in vivo. S. aureus incubated in vitro without tibiae disclosed no glycocalyx. Bone chips studied in vitro disclosed staphylococci more commonly near the endosteal Haversian portals than on the intervening endosteal surfaces (mean +/- SE, 280 +/- 75 vs. 12 +/- 3 per 2,500-micron 2 field; P less than .002 by Student's t test). Organisms within ostia were not counted, although they occluded 10%-40% of the ostium. Staphylococci were adherent to exposed woven material, perhaps collagen.

Synergism between Bacteroides fragilis and Staphylococcus aureus in experimental tibial osteomyelitis.

We explored the potential role of microbial synergy in an experimental rat osteomyelitis model. Osteomyelitis was assessed by gross pathologic conditions and quantitative cultivation of rat tibiae for the implanted organisms 21 days after challenge. When Staphylococcus aureus was used alone, the 50% infective dose (ID50) and the 100% infective dose (ID100) were 400 and 25,000 colony-forming units (CFU), respectively. When Bacteroides fragilis was inoculated alone, the ID50 was 150,000 organisms, and the ID100 was not confidently determined. Subinfectious numbers of B. fragilis added to the staphylococcal inocula yielded an ID100 as low as 20 staphylococci. Mixed inocula with 20 or 200 staphylococci and increasing numbers of B. fragilis yielded a dose-dependent increase in the number of staphylococci isolated from osteomyelitic tibiae. Multiple linear regression analysis confirmed the two inocula and their interaction to be significantly predictive of the 21-day quantitative assessment of staphylococci (r = 0.80). Synergy was most striking at low bacterial inocula. When even large numbers of S. aureus were added to B. fragilis, the B. fragilis inoculum required to initiate B. fragilis osteomyelitis was essentially unchanged. We conclude that small numbers of B. fragilis allow remarkably low numbers of S. aureus (20 or 200 CFU) to establish osteomyelitis in the rat.

Iontophoresis of vidarabine monophosphate for herpes orolabialis.

The cutaneous application of antiviral agents was studied by iontophoresis, a process that increases penetration of most drugs 20- to 60-fold. Twenty-seven subjects with vesicular orolabial herpes were treated one time in a double-blind, placebo-controlled clinical study: nine received vidarabine monophosphate (ara-AMP), nine received acyclovir (ACV), and nine received NaCl. Ara-AMP-treated lesions yielded lower titers of virus after 24 hr compared with lesions treated with NaCl or ACV (P less than .05). Ara-AMP significantly decreased the duration of shedding of virus (P less than .05) and time to dry crust (P less than .05) compared with the other two agents. There was a trend toward decreased healing time after ara-AMP treatment.

Effect of ibuprofen on gross pathology, bacterial count, and levels of prostaglandin E2 in experimental staphylococcal osteomyelitis.

Infections with Staphylococcus aureus were induced in rat tibiae without sclerosing agents. Animals received ibuprofen or 0.9% NaCl. Both ibuprofen-treated and control animals developed a progressively more-destructive disease over 12 days. Gross tibial pathology was significantly reduced in animals receiving ibuprofen for both six and 12 days postinfection. Radiographic evidence of osteomyelitis was attenuated at 12 days. Geometric mean counts of S. aureus were, however, not significantly changed by ibuprofen treatment. Mean levels of prostaglandin E2 (PGE2) were highest in untreated controls. Ibuprofen treatment of infected animals was associated with a much-reduced mean value of PGE2. Ibuprofen-treated infected tibiae disclosed less PGE2 than did either ibuprofen- or NaCl-treated uninfected tibiae.

In-vitro activity of BMY 28142, a new aminothiazolyl cephalosporin.

The in-vitro activity of BMY 28142, a new alpha-methoxyimino aminothiazolyl cephalosporin, was determined by microdilution broth techniques. The agent demonstrated excellent activity against recent clinical Enterobacteriaceae isolates with a 90% minimum inhibitory concentration (MIC90) of 0.25 mg/l or less for all but one species tested. BMY 28142 inhibited all Pseudomonas aeruginosa strains tested (MIC90 = 8.0 mg/l) as well as most other non-fermentative bacteria studied. Methicillin-susceptible Staphylococcus aureus were susceptible to BMY 28142 with MIC90 = 4.0 mg/l, while methicillin-resistant strains were generally resistant (MIC range 8- greater than 32 mg/l).