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Biomedical subjects

D Rimland

Publications and source records attributed to D Rimland.

7 recordsLinked to original sources

Epidemiologic typing of Staphylococcus aureus by DNA restriction fragment length polymorphisms of rRNA genes: elucidation of the clonal nature of a group of bacteriophage-nontypeable, ciprofloxacin-resistant, methicillin-susceptible S. aureus isolates.

Analysis of DNA restriction fragment length polymorphisms of rRNA genes (ribotyping) was employed to assist in the epidemiologic investigation of the emergence and spread of ciprofloxacin-resistant Staphylococcus aureus at the Atlanta VA Medical Center because many isolates of interest were nontypeable by phages and harbored few plasmids useful as strain markers. Chromosomal DNAs of selected S. aureus isolates were digested initially with 20 different restriction enzymes. EcoRI appeared to give the best discrimination of hybridization banding patterns (ribotypes) and was used with all study isolates. Overall, 15 different ribotypes were seen among the 50 S. aureus isolates studied (7 ribotypes among 13 methicillin-susceptible S. aureus [MSSA] isolates and 9 ribotypes among 37 methicillin-resistant S. aureus [MRSA] isolates). Seven of eight ciprofloxacin-resistant MSSA (CR-MSSA) patient isolates had identical antibiograms, were nontypeable by phages, and had a single 22-MDa plasmid. Six of these seven CR-MSSA isolates had an identical ribotype pattern. Ribotyping distinguished this CR-MSSA strain or clone from MRSA and other MSSA isolates, including nontypeable isolates that contained a 22-MDa plasmid. Five ciprofloxacin-susceptible MSSA isolates studied had five ribotypes; one pattern was identical to the CR-MSSA clone. Twenty-three CR-MRSA isolates recovered from the Atlanta VA Medical Center had four different ribotypes. Ribotyping proved to be a useful molecular epidemiologic tool in the study of S. aureus because it differentiated isolates which were indistinguishable by more traditional methods. In addition, this technique demonstrated that at our institution, ciprofloxacin resistance emerged in multiple strains of MRSA, as opposed to primarily a single strain or clone of MSSA.

Bacterial Typing Techniques

Rapid development of ciprofloxacin resistance in methicillin-susceptible and -resistant Staphylococcus aureus.

The fluoroquinolones, particularly ciprofloxacin, have been suggested to treat methicillin-resistant Staphylococcus aureus (MRSA) infections and colonization and methicillin-susceptible S. aureus (MSSA) infections. The development of ciprofloxacin resistance in MRSA and MSSA was prospectively evaluated. After 3 months of ciprofloxacin use, high-level resistance (MIC90, 64 micrograms/ml) developed in MRSA and increased at an alarming rate, from none to 79% over a 1-year period. High-level ciprofloxacin resistance also developed in MSSA, increasing to 13.6% over the same period. Antibiograms, phage typing, and plasmid profile analysis suggest that more than one clone of MRSA developed resistance and that ciprofloxacin resistance is not associated with the acquisition of a new plasmid. Most patients had nosocomial acquisition and about one-half had a history of previous ciprofloxacin use. Ciprofloxacin resistance can develop rapidly in S. aureus; thus, ciprofloxacin appears to have limited usefulness in treating staphylococcal infections and colonization, especially those due to MRSA.

Ciprofloxacin

Analysis of amikacin-resistant Pseudomonas aeruginosa developing in patients receiving amikacin.

During a 36-month period, 28 patients treated for infections due to amikacin-susceptible Pseudomonas aeruginosa subsequently developed infections or colonization with amikacin-resistant P aeruginosa at the same site. Eleven amikacin-susceptible/-resistant pairs of isolates were analyzed for aminoglycoside-inactivating enzymes, plasmid profiles, cellular proteins, outer membrane proteins (OMPs), lipopolysaccharide (LPS) profiles, and amikacin uptake. While clearly distinct from isolates of other patients, sensitive and resistant isolates from the same patients were indistinguishable in plasmid profile, LPS profiles, and OMPs. These results suggest that the resistant P aeruginosa isolates were derived from the sensitive isolates. None of the resistant isolates produced enzymes known to inactivate amikacin. In nine of 11 resistant isolates tested, transport of amikacin into P aeruginosa was reduced. A major mechanism of in vivo development of amikacin resistance in P aeruginosa is alteration in permeability to amikacin, but the aquisition of plasmids or changes in OMPs or LPS profile may not account for this phenomenon.

Amikacin

Spontaneous peritonitis: a reappraisal.

Spontaneous bacterial peritonitis occurs frequently in cirrhotic patients. In order to define more accurately the spectrum of this disease, 55 cases of spontaneous peritonitis were compared with 56 controls (patients with negative ascitic fluid cultures). Of several presenting symptoms, only vomiting (p less than 0.01), fever (p less than 0.05), and severe gastrointestinal bleeding (p less than 0.05) were more prevalent in cases than controls. There were no physical signs and no laboratory studies that separated the two groups except for elevated serum amylases in controls. Studies of peritoneal fluid were rarely helpful and cell counts overlapped in the cases and controls. Spontaneous peritonitis is usually seen in patients with severe liver disease, but there are few distinctive symptoms, signs, or laboratory findings. The mortality rate is high, and it is uncertain from our data that antibiotic therapy alters this prognosis.

Adult

Gonococcal endocarditis in the antibiotic era.

Since the introduction of penicillin in 1942, there have been only 11 culture-proven cases of gonococcal endocarditis in the English literature. Most patients are under 30 years of age and have no history of heart disease. The aortic valve is often involved and aortic regurgitation is common. The bacteriologic diagnosis can be difficult and may require more than six blood cultures and a long incubation period. Circulating immune complexes appear to be the cause of many of the extracardiac manifestations. The three new cases reported herein and review of the literature emphasize the distinctive features of gonococcal endocarditis.

Adult

Hepatitis B outbreak traced to an oral surgeon.

Over a four-year period in a five-county area, 71 patients with clinical hepatitis B had dental work performed in the two to six months before their illness. Fifty-five cases were traced to a single oral surgeon. Seventy-nine per cent of these patients were positive for hepatitis B surface antigen (HBsAg) and most had no other recognized source of hepatitis. An investigation of the implicated dentist uncovered no gross inadequacies in instrument sterilization or general dental procedures; however, the dentist was found to be an asymptomatic carrier of HBsAg of the same subtype (ay) as nine of 11 of his patients who had hepatitis and whose serums were available for testing. Since no HBSAg was found in the dentist's saliva, urine or feces, and since he admitted to having frequent cuts on his fingers, it is possible that a "hemoral" transmission of HBs Ag produced hepatitis in his patients.

Adolescent

Immunization for the internist.

The emphasis of immunization programs and schedules has traditionally been directed to infants and children, since most of the vaccine-preventable diseases are seen predominantly in these age groups. Immunization procedures in adults are less well defined but still of importance. Diseases for which immunizations are given before disease exposure include tetanus, diphtheria, influenza, rubella, and mumps; travelers to foreign countries may need immunizations against typhoid, cholera, yellow fever, typhus, poliomyelitis, plague, and viral hepatitis; other vaccines are available before disease exposure in unusual epidemiologic situations. After exposure to disease but before onset of symptoms, immunizations are available for rabies, viral hepatitis, and measles. After the onset of clinical illness, passive immunization should be given for tetanus, diphtheria, and botulism. This paper summarizes current practices for active and passive immunization against these diseases in adults.

Adolescent