Adherence of glucan-positive and glucan-negative streptococcal strains to normal and damaged heart valves.

The adherence of 18 strains of streptococci to sections of normal canine and human aortic, mitral, and tricuspid valves and to canine interatrial septum was compared in an in vitro system. Quantitative measurements of adherence ratios were performed by two independent methods. Adherence ratios for Streptococcus mutans, S. sanguis, S. bovis, and Group D streptococci were higher (0.0058-0.0101) than for the other streptococcal strains studied (0.0025-0.0041). With the exception of Group D streptococci, adherence ratios for each bacterial strain were similar with the aortic, mitral, and tricuspid valve sections. Adherence ratios with normal human and canine valve leaflets were similar, but adherence ratios with interatrial septum were lower than with normal valve sections. Adherence ratios for glucan-positive and glucan-negative strains of streptococci with normal and with damaged aortic valve leaflets were also compared. The adherence ratios of the glucan-positive streptococci (S. mutans, S. sanguis, and S. bovis) and one glucan-negative enterococcal strain (KG-3) were approximately five times higher with damaged aortic valves (0.039-0.051) than with normal aortic valves (0.009-0.010). For glucan-positive strains, adherence ratios with normal aortic leaflets were similar when bacteria were grown in media which contains or lacks sucrose. In striking contrast, growth of the glucan-positive strains in medium which lacks sucrose, with resultant deficiency of glucan production, decreased the adherence ratios with damaged aortic valve leaflets to those found with normal aortic leaflets. Treatment of glucan-positive strains with dextranase resulted in a decrease in their adherence ratios to levels seen with bacteria grown in medium lacking sucrose, but the higher adherence ratios could be restored in the presence of exogenous dextran.It is concluded that glucan production is one quantitatively important factor that contributes to the greater adherence of glucan-positive streptococci to damaged rather than to normal aortic heart valve leaflets. However, glucan production is not the only factor that determines preferential adherence of streptococci to damaged heart valves, because glucan-negative strains may also show some degree of increased adherence to damaged valves. Thus, bacterial glucan production is one of the factors that could contribute to the pathogenesis of bacterial endocarditis.

Adherence of bacteria to heart valves in vitro.

The abilities of 14 strains of aerobic gram-positive cocci and gram-negative bacilli to adhere in vitro to human or canine aortic valve leaflets were compared. 2-mm sections of excised valve leaflets were obtained by punch biopsy and were incubated under standardized conditions in suspensions of bacteria. Valve sections were subsequently washed and homogenized, and quantitative techniques were used to determine the proportions of bacteria from the initial suspensions that had adhered to the valve sections. Comparable results were obtained when these adherence ratios were determined by two independent methods based either on measurements of bacterial viability or of radioactivity in 51Cr-labeled bacteria. For each bacterial strain, the adherence ratio was constant over a wide range of concentrations of bacteria in the incubation medium. Strains of enterococci, viridans streptococci, coagulase-positive and coagulase-negative staphylococci and Pseudomonas aeruginosa (adherence ratios 0.003-0.017) were found to adhere more readily to valve sections than strains of Escherichia coli and Klebsiella pneumoniae (adherence ratios 0.00002-0.00004). The organisms that most frequently cause bacterial endocarditis were found to adhere best to heart valves in vitro, suggesting that the ability to adhere to valvular endothelium may be an important or essential charcteristic of bacteria that cause endocarditis in man.

Pharyngeal flora in ambulatory alcoholic patients: prevalence of gram-negative bacilli.

The pharyngeal flora of a group of ambulatory alcoholic patients was studied and compared with the pharyngeal flora of a control group. Sixty-eight patients were studied, 34 alcoholics and 28 controls. Of the alcoholic patients, 59% had Gram-negative bacilli in their pharyngeal flora, while 14% of the control group had the same organisms. There were no differences in Gram-positive cocci colonization between the groups. Klebsiella pneumoniae was the most frequent isolate (40%) and the Klebsiella-Enterobacter group accounted for 76% of the isolates. Colonization rates of greater than 10 colony forming units/ml were found in 43% of the alcoholic patients. The high prevalence and higher colonization rates of Gram-negative bacilli in alcoholic patients might explain the higher incidence of Gram-negative bacillary pneumonia among alcoholics.

Increased pharyngeal bacterial colonization during viral illness.

The oropharyngeal colonization by Staphylococcus aureus and Gram-negative bacilli (GNB) and its duration were studied in 89 house staff officers, with biweekly quantitative cultures for 11 months. Eighty-two episodes of upper respiratory tract infection were documented during the study period. The oropharyngeal colonization during illness-free periods ranged from 12% to 18% for GNB and from 5% to 14% for S aureus. During an episode of upper respiratory tract infection, the oropharyngeal colonization of GNB increased to 60%; S aureus colonization increased to 43%. The colonization with both GNB and S aureus was transient and lasted for approximately two weeks. The increased colonization by S aureus and GNB during a viral respiratory tract infection may be a factor contributing to the increased risk of pneumonia in patients with this condition.

Oral ciprofloxacin vs parenteral cefotaxime in the treatment of difficult skin and skin structure infections. A multicenter trial.

A prospective, randomized, double-blind, multicenter study was conducted of hospitalized patients to compare the efficacy and safety of oral ciprofloxacin (dosage, 750 mg every 12 hours) with intravenous cefotaxime (dosage, 2.0 g every 8 hours) as monotherapy for difficult skin and skin structure infections requiring hospitalization. Five hundred seventy patients were assessed for an analysis of safety and 461 patients were assessed for an analysis of efficacy. The most common infections were infected ulcers and abscesses. At the end of therapy, there was a higher incidence of recurrent or persistent organisms in the cefotaxime group compared with ciprofloxacin. Adverse reactions related to either therapy were rare. By pathogens, there were no differences in activity, except the higher rate of recurrent or persistent Pseudomonas aeruginosa infection in the cefotaxime group. By diagnosis, the two drugs had comparable efficacy, except for the higher incidence of bacteriologic failure in patients with polymicrobial infected ulcers in the cefotaxime group. Larger studies are needed to evaluate emergence of resistance to ciprofloxacin. Oral ciprofloxacin therapy is as safe and effective as parenteral cefotaxime in the treatment of difficult infections of the skin and skin structure, and affords the prospect of early discharge from the hospital and significant cost savings.

Comparative studies of two-times-daily versus three-times-daily indinavir in combination with zidovudine and lamivudine.

OBJECTIVES: To compare the efficacy and safety of two-times-daily versus three-times-daily indinavir in combination with zidovudine and lamivudine. DESIGN: Two multicenter, open-label, randomized 24-week studies. METHODS: Adults HIV-1 infection, HIV-1 RNA greater than 10000 copies/ml, and no prior lamivudine or protease inhibitor therapy were eligible. In a pilot study (Study A), patients received indinavir at 800 mg every 8 h, 1000 mg every 12 h, or 1200 mg every 12 h. In a subsequent study (Study B), patients received indinavir at 800 mg every 8 h or 1200 mg every 12 h. All subjects received zidovudine (300 mg) and lamivudine (150 mg) every 12 h. An intent-to-treat analysis was used. RESULTS: In Study A, which enrolled 88 patients, neither HIV-1 RNA nor CD4 cell responses differed significantly between treatment groups at 24 weeks when corrected for multiple comparisons. Study B enrolled 433 patients, but was prematurely discontinued when interim analysis suggested greater efficacy of three-times-daily indinavir. Of the first 87 patients reaching week 24, HIV-1 RNA was less than 400 copies/ml in 91% receiving three-times-daily versus 64% receiving two-times-daily indinavir (P < 0.01). CONCLUSION: Three-times-daily indinavir appears more efficacious than two-times-daily dosing when administered with zidovudine and lamivudine. Two-times-daily indinavir dosing should only be considered in situations characterized by favorable pharmacokinetic drug-drug interactions.

Dengue and hepatic failure.

Dengue hemorrhagic fever/dengue shock syndrome is a serious manifestation of dengue fever, which is observed predominantly in the tropical regions of the West Pacific and in Southeast Asia and is associated with secondary infections, mainly in children under age 15. A concomitant microangiopathic coagulopathy has been described; moreover, encephalopathy and even Reye's syndrome have been rarely reported. This report describes a 51-year-old man with secondary dengue infection who presented with clinical evidence of severe hepatitis, encephalopathy, cranial nerve palsy, and microangiopathic coagulopathy and who had a favorable outcome. A careful surveillance for the occurrence of secondary dengue in the Western Hemisphere is proposed, and dengue is suggested as a diagnostic possibility in obscure febrile illnesses presenting as either hepatitis, encephalopathy, or coagulopathy in places in which the mosquito vector, Aedes aegypti, is present.

Efficacy and safety of aztreonam versus tobramycin for aerobic gram-negative bacilli lower respiratory tract infections.

Aztreonam therapy was evaluated for the management of 80 patients with gram-negative bacilli lower respiratory tract infections. Study results confirmed its efficacy and safety for this indication.

Susceptibility of aerobic gram-negative bacilli to aminoglycosides. Effects of 45 months of amikacin as first-line aminoglycoside therapy.

Amikacin was instituted as the primary empiric aminoglycoside at the San Juan Veterans Administration Medical Center in January 1982; at that time, 16 percent of the strains at the hospital were gentamicin-resistant. A prospective surveillance study was designed to correlate detection of bacterial resistance with aminoglycoside use. In the current report, the baseline period, during which gentamicin was the first-line aminoglycoside, accounting for 61 percent of overall aminoglycoside use, is compared with the period from January 1982 to September 1985, during which the first-line aminoglycoside was amikacin, accounting for 85 percent of overall use. This study is ongoing. During the two periods, the patient population did not differ with regard to aminoglycoside therapy, indications, or overall aminoglycoside use (541 versus 680 patient days per month). Among the gram-negative bacilli isolated, the percent of strains resistant to amikacin was as follows: pre-baseline period/baseline period, 0.8/0.2 percent; amikacin-usage period, 3.6 percent. Resistance to gentamicin and tobramycin during the period of amikacin use decreased from 16 to 11 percent for gentamicin and from 17 to 11 percent for tobramycin. The decrease in resistance of the gram-negative bacilli to gentamicin varied among strains: the resistance of Escherichia coli decreased from 8 to 4 percent; that of Proteus mirabilis, from 12 to 5 percent; that of indole-positive Proteus, from 19 to 12 percent; that of Acinetobacter, from 57 to 23 percent; that of Citrobacter, from 15 to 7 percent; and that of Pseudomonas aeruginosa, from 24 to 16 percent. During the amikacin-usage period, amikacin resistance was unchanged for most strains, with the exception of P. aeruginosa, the resistance of which increased from 4.5 to 7.8 percent. Of the 4,795 strains isolated, 174 were resistant to amikacin; of these, 29 Pseudomonas strains were studied for all mechanisms of resistance. Changes in permeability were exhibited by 11 of the 29 strains; 14 strains exhibited the AAC(6')-I enzyme, 10 strains exhibited the APH(3')-II enzyme, and two strains exhibited ANT(2") in addition to some other unidentified mechanism. Multiple enzyme production was found in 15 of the strains. The use of amikacin as a first-line aminoglycoside is associated with a decrease in resistance to other aminoglycosides and a slight increase in overall resistance to amikacin among aerobic gram-negative bacilli. The usefulness of amikacin has not been affected at our institution.

Comparative, double-blind study of oral ciprofloxacin and intravenous cefotaxime in skin and skin structure infections.

The effectiveness and safety of orally administered ciprofloxacin and intravenously administered cefotaxime were compared in a double-blind study of 60 men with infections of skin and soft tissue, including cellulitis, ulcers, abscesses, cellulitis with ulcers or abscesses, wound infections, and post-traumatic infections. Patients in the ciprofloxacin group received 750 mg orally every 12 hours for a mean duration of 9.6 days (six to 18 days), and those in the cefotaxime group received 2.0 g intravenously every eight hours for a mean duration of 9.3 days (five to 14 days). Infection was documented bacteriologically in 78 percent of the patients in the ciprofloxacin group and in 83 percent of the patients in the cefotaxime group. Pathogens included Staphylococcus aureus, enterococci, group B streptococci, Escherichia coli, Proteus mirabilis, and Klebsiella and Pseudomonas species. Half of the infections were mixed infections. Ninety percent (19 of 21) of the infections were bacteriologically eradicated with ciprofloxacin, and 82 percent (18 of 22) were eradicated with cefotaxime. Treatment was completely successful in 79 percent (22 of 28) of the patients in the ciprofloxacin group and in 68 percent (19 of 28) in the cefotaxime group (p greater than 0.1). The side effects in both treatment groups were comparable. This study demonstrates that orally administered ciprofloxacin is comparable in effectiveness and safety to cefotaxime administered intravenously in the treatment of infections of skin and soft tissue, and that it can offer an alternative in the treatment of such infections.

Dengue in the Western Hemisphere.

Dengue is an important insect-borne viral disease, transmitted in the Western hemisphere by the A. aegypti mosquito. It is endemic in the Caribbean with sporadic outbreaks in different regions. Cases in the United States are mostly imported cases but can be seen in the Gulf states as well as the Southeast. Dengue is most frequently a self-limiting illness characterized by sudden onset of fever, chills, headache, retroocular pain, general malaise, myalgias, arthralgias, and a skin rash. In a small group of patients, the same viruses may cause dengue hemorrhagic fever and dengue shock syndrome. In the Western hemisphere, dengue with hemorrhagic manifestations and dengue with shock syndrome have been documented frequently in adults. There are four serotypes of dengue viruses and all have been documented to be present in the Western hemisphere. The clinical illness is similar for any of the four serotypes; after infection there is lifelong homotypic immunity and heterotypic immunity for several months. The diagnosis of dengue is based on clinical findings and can be confirmed by serologic tests or virus isolation. There is no specific treatment for dengue; hydration is important as well as aggressive fluid management if hypotension develops. It is important to avoid aspirin and salicylates. The best treatment is prevention through mosquito control and public education to eradicate the breeding grounds for the mosquito.

Dengue in Puerto Rico: clinical manifestations and management from 1960's to 1987.

Dengue is a viral disease transmitted by the Aedes aegypti mosquito. It is endemic in Puerto Rico and the Caribbean with periodic epidemics occurring at varying intervals. There are three dengue serotypes present in Puerto Rico, at the present time. The clinical manifestations of dengue in Puerto Rico are presented from a historical perspective. Dengue in Puerto Rico has evolved from a clinically mild illness in the 1960's to a devastating disease with hemorrhagic manifestations in the 1980's and dengue shock syndrome in 1987. The approach to clinical diagnosis and management is presented with emphasis on early recognition, performance of tourniquet test, serial hematocrits and aggressive intravenous fluid replacement with crystalloids of colloids in DSS. The best way to treat dengue is eliminating the vector, therefore, prevention.

[Infections of penile prosthesis: treatment and prevention]. / Infecciones en prótesis de pene: tratamiento y prevención.

To date, there are 10,000,000 men with impotence in the United States and it is estimated that at least 17,000 penile prosthesis are implanted annually. The most fearsome complication is the infection of the prosthesis which is usually caused by Staphylococcus epidermidis (in 40-80% of the cases). In general, the incidence of infection is actually 0.8-8.3%, but it can increase to 37% in patients with tertiary implants. The initial empiric treatment is usually with vancomycin and aminoglycosides and prophylaxis is recommended with a penicillinase-resistant synthetic penicillins, first generation cephalosporins, or vancomycin in case of penicillin allergy.

[Parvovirus infections in humans]. / Infecciones por parvovirus en humanos.

The Human Parvovirus (HPV) like other Parvovirus is a single strand DNA virus with autonomous replication which measures 23mm. Infection with this virus is followed by a non-specific viral syndrome during the prodrome, leading to viremia, which may be followed by arthropathy and/or different kind of rash including the syndrome called erythema infectiosum. It has also been related to an increase in the number of spontaneous abortion in pregnant women with acute infection; and it is the etiology of the aplastic crisis in patients with hemolytic anemias. Many other Parvovirus serologically different from HPV are present in stools and are responsible for acute infectious non bacterial gastroenteritis in people more than 5 years old.

The new macrolides: expanding the ways in antibiotic treatment.

After almost forty years of its introduction, erythromycin will not be the exclusive member of the macrolide group of antibiotic agents, but a new generation of its derivatives which surpass it in pharmacological properties and clinical efficacy will also be available. Clarithromycin, a 14-membered derivative, has shown acid stability, longer half-life, lower protein binding and higher lung tissue penetration. Its exceedingly high activity against erythromycin-susceptible gram-positive cocci, Mycoplasma pneumoniae, and Legionella pneumophila makes it and important alternative choice in the therapy of respiratory tract infections. Also, it has shown high activity against Chlamydia trachomatis, and high urinary clearance of this unmetabolized molecule, important properties which would render it a special role in the treatment of genitourinary tract infections. Azithromycin, a 15-membered derivative has shown enhanced basicity (due to the nitrogen atom in its lactone ring), longer half-life and lower protein bindings. Its exceptional activity against Hemophilus influenzae, Branhamella catarrhalis, Neisseria gonorrhoeae, Ureaplasma urealyticum and gram-negative bacteria, and its high concentration in tonsillar, pulmonary, prostatic and female reproductive tract tissues, assigns it an honorific place among the macrolides in the therapy against respiratory tract and genitourinary tract infections. Its role against T. gondii deserves further study, but points out this agent as a promise against this parasite.

Halophilic Vibrio infections: a review.

Halophilic vibrios are gram-negative curved bacilli that requires high concentrations of salt for survival. They are usually found in marine environments and have a worldwide distribution. Infections caused by these organisms are usually associated with ingestion of raw shell fish or exposure of wounds to sea water. The clinical presentation and severity of this infections is wide ranging. The most common presentation is self-limiting gastroenteritis, but soft tissue infections and septicemia do occur and their morbidity and mortality is high specially in patients with liver disease. Early detection and initiation of treatment with tetracycline is of vital importance in soft tissue infections and septicemia since the progression of the infection may be extremely fast.

Cytomegalovirus retinitis in AIDS patients: a clinical review.

Cytomegalovirus (CMV) retinitis is an ocular condition previously seen in organ transplant recipients, patient on chemotherapy for malignancy, and in infants with congenital infections. As it present in immunocompromised, the AIDS patient has integrated this group of patients that can present with CMV retinitis. Moreover, it is the leading cause of opportunistic ocular infection in the AIDS patient, and the second most common ocular manifestation. As new drugs and modes of administration are studied that can effectively halt this progressively blinding condition, the awareness and recognition of CMV retinitis on AIDS patients has become increasingly important. This author will review the epidemiology, clinical presentation, and differential diagnosis of this condition. The current treatments being used and complications will also be discussed.

[Pancreatic abscess and infected pseudocyst]. / Absceso pancreático y pseudoquiste infectado.

Acute pancreatitis is a sterile inflammatory process caused by a chemical auto digestion of the pancreas. The pancreatic abscess and infected pseudocyst are complications of acute pancreatitis of a high mortality rate that require a prompt diagnosis. The pseudocyst is defined as a localized collection of pancreatic juices confine to a retroperitoneal area by a fibrous membrane without epithelium; an abscess is a collection of pus and necrotic tissue. This illnesses should be suspected when patients with acute pancreatitis develop fever, tachycardia, abdominal distention or mass after 14-22 days after the initial attack. These entities require different treatment. The definite treatment is surgical intervention.

Hantavirus infection: a rare disease which you should be aware.

Hantavirus infection is caused by viruses classified in the Hantavirus genus, of the Bunyaviridae family. Recently a new hantavirus has been recognized. Specific endemic areas has been identified, however a new outbreak was identified in the southwestern of the United States. The principal vectors are rodents. Human infection occur by aerosol from rodent urine, saliva, feces and rodent bites. The infection classically is manifested clinically by fever, hemorrhage and renal failure. The recent outbreak was associated with acute respiratory illness without renal involvement. The treatment is with intravenous Ribavirin. Specific recommendations for prevention and control are presented here in.

Tetracyclines, macrolides, lincosamides & chloramphenicol.

Macrolides, lincosamides, tetracyclines and chloramphenicol are structurally unrelated antibiotics which share protein synthesis inhibition as their common mechanism of action. Despite their individual differences, they can all be considered broad spectrum antibiotics with practical use for a wide variety of infections. Due to their similarities in function, however, concurrent or sequential administration of these agents must be undertaken with caution in order to prevent antagonism and induction of bacterial resistance. Full understanding of their function and potential interactions are, therefore, important. Indications, interactions, mechanisms of function, side effects and contraindications are fully discussed.