Bacteraemia in Dublin due to gentamicin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus: impact on dermatology practice

Methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) emerged in the 1960s and is now commonly seen in hospitals, clinics and, since the mid-1990s, the community. Risk factors for the acquisition of MRSA include chronic dermatoses, underlying medical illnesses, attending healthcare facilities, use of prescription antibacterials, surgery, intravenous lines, hospitalization in an intensive care unit, and proximity to patients colonized with MRSA. Recent community-associated strains often occur in patients without these risk factors. Staphylococci are readily spread from person to person and readily contaminate the environment. Infection control measures thus involve identifying the infected patients, separating them from other non-infected patients, cleaning of the environment and, most important of all, scrupulous attention to hand hygiene. Alcoholic antiseptic hand rubs offer an alternative to antiseptic hand washes and increase compliance. Treatment of MRSA skin infections is challenging. Topical agents such as mupirocin or fusidic acid can be used, but the organisms often become resistant. Systemic therapy involves non-beta-lactams. Parenteral treatment is generally with glycopeptides such as vancomycin; oral therapy is more complex. Monotherapy with quinolones, rifampin (rifampicin), and fusidic acid often results in the development of resistance and so, if any of these agents are chosen it should be in combination. There are no data on combination therapy, although rifampin-containing combinations are often chosen. Fourth-generation quinolones and linezolid are expensive but promising alternatives.

Tuberculous pericarditis with rapid progression to constriction. Prompt diagnosis and treatment are needed

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Postoperative complications due to methicillin-resistant staphylococcus aureus (MRSA) in an elderly patient: management and control of MRSA

An elderly lady was admitted to hospital for elective resection of an adenocarcinoma of the colon. Following an anastomotic leak she developed intra-abdominal sepsis and underwent abdominal drainage of pus. During recovery from her second operation, she developed pneumonia and a bacteraemia due to methicillin-resistant Staphylococcus aureus (MRSA). She was treated with vancomycin and co-trimoxazole and survived without further sequelae. Details of the development and treatment of this case are discussed. Procedures for the control and eradication of MRSA infections in hospitals are reviewed.

Nasal carriage of methicillin-resistant Staphylococcus aureus by hospital staff in north Jordan

The nasal carriage of methicillin-resistant Staphylococcus aureus was detected in 550 hospital staff members of four hospitals in north Jordan. Of the 109 (19.8%) individuals tested who were nasal carriers of S. aureus, only 32 (5.8%) were found to be carriers of methicillin-resistant Staphylococcus aureus. The carriers were four doctors, 23 nurses, three laboratory technicians, one maid and an administrator. It was noted that 25 (78.1%) of these carriers were in constant contact with patients in operating theatres, surgical wards or intensive care units. It was not clear whether the carriers were short- or long-term carriers, or whether they were persistent sources of methicillin-resistant Staphylococcus aureus. Decontamination of these carriers was considered among other control measures to avoid the dangerous outcome of hospital outbreaks caused by this potential pathogen.

Nasal carriage of Staphylococcus aureus and its influence on hospital infections caused by methicillin-resistant strains

A short review of the literature on the actual epidemiological situation related to nosocomial infections caused by methicillin-resistant Staphylococcus aureus and the importance of the nasal carriage of this pathogen is given together with selected data derived from our own studies on these problems.

The changing pattern of severe neonatal staphylococcal infection: a 10-year study

Forty-two cases of severe staphylococcal infection occurring over a 10-year period in the neonatal unit at Queen Mary Hospital are described. There was a 4.5-fold increase in incidence in the latter half of the study period, when methicillin-resistant Staphylococcus aureus (MRSA) emerged. The isolated MRSA were also resistant to gentamicin, but sensitive to vancomycin, fusidic acid, co-trimoxazole and amikacin. Comparison between MRSA and methicillin-sensitive cases showed that the former was associated with a longer hospital stay after diagnosis. Overall mortality was 9.5%. Two cases with meningitis died. MRSA is at least as virulent as its methicillin-sensitive counterparts. The treatment implications of severe neonatal staphylococcal infection are discussed.

An international study on the occurrence of multiresistant bacteria and aminoglycoside consumption patterns

The correlation between aminoglycoside consumption patterns and the occurrence of aminoglycoside-resistant bacteria from 12 different countries was analyzed. Regional and national data were collected retrospectively and compared. There was evidence of a wide variation of the national aminoglycoside consumption patterns in the different countries. There was a striking correlation of gentamicin resistance and the total national aminoglycoside and national gentamicin consumption. In addition, there was a clear correlation between bacterial resistance inside and outside the hospital to the total amount of aminoglycoside, particularly gentamicin, consumption in hospitals. In a number of countries, an increase in the frequency of gentamicin-resistant bacterial strains could be noticed. For amikacin, only a correlation of staphylococcal resistance in hospitalized patients to the total amount of national aminoglycoside and amikacin consumption could be found.

Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong

In the first 22 months of operation at the Prince of Wales Hospital, 26 (46%) of 56 hospital-acquired Staphylococcus aureus bacteraemias were due to methicillin-resistant organisms (MRSA). There were 10 plasmid profiles amongst 24 of the MRSA strains analysed. MRSA bacteraemias were first seen in the hospital 1 year after opening when the isolation rate of MRSA from all sites had risen to about 1% of patient admissions. During the last 3 months of the study period, 17 out of 18 S. aureus bacteraemias were due to methicillin-resistant strains. Patients with MRSA bacteraemia were significantly more likely than those with methicillin-sensitive S. aureus bacteraemia to have had a severe underlying disease, a poor clinical prognosis, prolonged hospitalization, and prior antimicrobial therapy, especially with aminoglycosides. They also had a significantly longer hospital stay after infection, a significantly higher cost of antimicrobial therapy and a higher mortality rate. The lower mortality rate in MRSA patients treated with vancomycin (18%) compared with those treated with other antimicrobials (40%) confirms that, at present, vancomycin is the treatment of choice for invasive MRSA infections.

Sources and outcome for methicillin-resistant Staphylococcus aureus bacteraemia

Eighty-eight episodes of MRSA septicaemia occurring in 82 patients were studied prospectively. In 15 episodes bacteraemia was transient, in 36 non-fatal, in 33 fatal, while in four septicaemia was a major contributory factor in the patient's death. There were more patients aged over 60 years in the septicaemia groups compared to the transient bacteraemia group (P = 0.01), and patients with septicaemia were usually recently postoperative and/or suffering from severe underlying disease. Circulation access sites were the commonest source of the bacteraemic organisms with non-surgical wounds including burns, varicose ulcers and bed sores as the next most common. In four of the 16 burns patients, fatal septicaemia followed surgical debridement of infected burns. In only eight episodes was there no apparent source of bacteraemia.

Antimicrobial resistance of Staphylococcus aureus: genetic basis

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The international spread of methicillin-resistant Staphylococcus aureus

A genetic analysis of representative methicillin-resistant Staphylococcus aureus (MRSA) being isolated in London and Dublin hospitals has demonstrated that the epidemic strains from two London hospitals are different from the Dublin strains, but indistinguishable from the epidemic strains of eastern Australia. The possibility that some strains of MRSA are more likely than others to spread within hospitals is discussed.

Methicillin-resistant Staphylococcus aureus: a 6-month survey in a Lisbon paediatric hospital

The prevalence of nasal colonization and infection with methicillin-resistant Staphylococcus aureus (MRSA) among patients and staff was studied in a section of a Paediatric Surgical Unit in Lisbon between February and July 1985. Nasal colonization was demonstrated in 41% of burned patients, 5% of non-burned patients and 35% of the nurses. Infection by MRSA occurred in 30% of the burns. The isolates had identical serological patterns, slight differences on phage typing and were resistant to methicillin, cephalosporins, tetracycline, erythromycin and aminoglycosides. A chloramphenicol resistance plasmid of 3 Md was present in those isolates which were chloramphenicol resistant and a small plasmid of 1.7 Md which coded for constitutive erythromycin resistance was present in many isolates. Gentamicin, tetracycline and inducible erythromycin resistance were chromosomal. Several reasons for the apparent low virulence of the isolates are discussed. Attempts to control the outbreak by the discharge of colonized or infected patients, improvement of nursing practices and treatment with temporary removal from work of the colonized nurses did not eliminate the organism from the unit.

Properties of methicillin-resistant Staphylococcus aureus colonizing patients in a burns unit

One hundred cultures of methicillin-resistant Staphylococcus aureus (MRSA) were isolated from patients in a Regional Burns Unit between December 1984 and May 1985. These organisms produced large amounts of beta-lactamase which readily hydrolyzed flucloxacillin but they were sensitive to teicoplanin, dicloxacillin and cephalothin at 37.5 degrees C. The MRSA strains did not differ from methicillin-sensitive isolates in sensitivity to unsaturated fatty acids, survival in serum and plasma or desiccation. However, each culture of this strain was negative or only weakly-positive for bound coagulase and cell bound protein A. Few (eight out of 44) cultures contained plasmids and the resistance to four antibacterials was not transferable in mixed cultures. No attempt was made to isolate patients colonized with MRSA which were rarely isolated elsewhere in the hospital.

Antimicrobial chemotherapy of septicemia due to methicillin-resistant Staphylococcus aureus

The outcome of treatment of 48 episodes of septicemia due to methicillin-resistant Staphylococcus aureus (MRSA) in 44 patients was assessed. Twenty-six of the patients died; nineteen of them died of infection, and infection was a major contributing factor to the deaths of the remaining seven patients. Fourteen of fifteen patients treated with inadequate antibiotic therapy died, and the other patient developed a mycotic aneurysm of the femoral artery, for which amputation was necessary. Eight of eleven patients treated with amikacin (alone or combined with another antimicrobial) died, and three recovered slowly; only one recovered fully without sequelae. In an additional two patients who failed to respond to amikacin, treatment was changed to vancomycin. Vancomycin was used to treat 18 episodes of MRSA septicemia in 17 patients. In 14 of these episodes the patients recovered fully. One patient died of uncontrolled infection, and in three, infection was a contributing factor but not the major cause of death. Vancomycin was confirmed as antibiotic of choice in treating MRSA septicemia.

Methicillin-resistant Staphylococcus aureus in Dublin 1971-84

Between 1971 and 1975, methicillin-resistant Staphylococcus aureus (MRSA) caused sporadic infection in eight Dublin hospitals although a case of bacteraemia was not recorded until 1976. From then on gentamicin-resistant MRSA rapidly became endemic in Dublin hospitals. The frequency of MRSA bacteraemia reached a peak in 1979-82 but MRSA infection remains an important problem. The most effective antimicrobial agent in treatment of invasive infection was vancomycin; little drug toxicity was seen. Where appropriate, concomitant surgical treatment such as debridement and drainage was usually necessary. Infection control measures directed at eliminating carriage proved effective in reducing spread. Molecular analysis showed two distinct MRSA phenotypes with similar phage-typing patterns. Gentamicin resistance was chromosomally encoded.

In vitro activity of six antibiotics against multiresistant staphylococci and other gram-positive cocci

Sixty-two strains of Staphylococcus aureus and coagulase-negative staphylococci, 21 Streptococcus faecalis and 17 other strains of streptococci isolated from cases of endocarditis were tested for sensitivity against rifampicin, teicoplanin, vancomycin, fusidic acid, erythromycin and novobiocin. Only rifampicin, novobiocin and teicoplanin were found to be active against the great majority of these strains. The microbial properties of these antibiotics suggest the necessity of combinations for effective therapy. The combinations rifampicin + novobiocin and rifampicin + teicoplanin were additive and suppressed the emergence of resistant mutants. Thus according to in vitro tests, either of these two combinations would be suitable for prophylactic use in high-risk patients, especially those scheduled to receive prosthetic implants.

Stability of aminoglycoside resistance in vitro in gentamicin-resistant Staphylococcus aureus

Stability of aminoglycoside resistance has been investigated in 20 strains of Staphylococcus aureus resistant to gentamicin (16 strains were also resistant to methicillin). In view of previous reports that incubation at elevated temperatures can hasten the loss of unstable antibiotic resistance, we passaged strains daily in a liquid medium for 24 days at 43 degrees C. The nine strains which were resistant to neomycin kept their aminoglycoside resistance virtually intact, whereas most of the other 11 strains (sensitive to neomycin) lost almost all their resistance to gentamicin and kanamycin after 5 days. It thus appears that the stability of aminoglycoside resistances in Staph. aureus is closely linked to the resistance of the strains to neomycin. This finding has important possible consequences in terms of the advisability of the clinical usage of preparations containing neomycin or framycetin for topical application and bowel sterilization.

Bacteremia in a Swedish university hospital: a one-year prospective study in 1981 and a comparison with 1975-76

A one-year prospective study of bacteremia was carried out at a Swedish university hospital. Blood cultures were taken in 6.3% of all patients admitted to the hospital. 148 episodes of bacteremia were recorded in 142 patients, 59% of whom were males. The mean incidence of bacteremia was 4.3 episodes per 1,000 admissions. The incidence of contamination was 1.3%. Malignancy and urinary tract disorders were the most common diagnoses and surgical intervention, central venous catheters and cytostatic drugs the most common predisposing factors. The ratio of hospital to community-acquired bacteremia was 1.3:1. The fatality rate was 12.7%. Gram-negative rods belonging to the Enterobacteriaceae were the most common pathogens, followed by Staphylococcus aureus and Staphylococcus epidermidis. The antibiotic sensitivity pattern of the causative bacteria was quite favorable. No S. aureus strains were resistant to isoxazolyl penicillins or gentamicin. No Klebsiella strain and only one Escherichia coli strain was resistant to gentamicin. The results were compared to a one-year retrospective study carried out in the same hospital five years ago. The incidence of bacteremia had not increased between the two studies.

Multiply-resistant Staphylococcus aureus (bacteriophage type 90) in a special care baby unit

An outbreak of infection in a special care baby unit due to a multiply-resistant Staphylococcus aureus is described. Although the organism was isolated from 35 babies over 1 year, only two were clinically infected, one of whom died of infection. New measures to prevent cross-infection were introduced but colonized babies continued to be detected. The unit was closed for several weeks but babies became colonized again after reopening. The route of cross-infection remained uncertain.

Staphylococcus aureus bacteraemia: 400 episodes in St Thomas's Hospital

Four hundred episodes of Staphylococcus aureus bacteraemia occurred in St Thomas's Hospital from 1969 to 1983, accounting for 17.5% of all episodes of bacteraemia. The mortality was 24%, half attributable to underlying disease, and was highest in patients over 50. Almost 60% of the bacteraemias were acquired in hospital, and the source of the organism was generally obvious, with vascular access sites the most common (37%). Bone and joint infections accounted for 11.5% of episodes and endocarditis for 7%. Most staphylococci were resistant to penicillin only; three isolates were resistant to methicillin and five to fusidic acid. Microbiologists seldom influenced directly the choice of initial antibiotic treatment (though this usually conformed to the hospital's antibiotic prescribing policy) but had considerable influence over definitive treatment, usually cloxacillin or flucloxacillin alone or in combination with fusidic acid. S aureus bacteraemia is easy to identify and treat, though underlying disease may influence the outcome. Efforts should be made to prevent the largely iatrogenic disease.

Analysis of plasmids in nosocomial strains of multiple-antibiotic-resistant Staphylococcus aureus

Nosocomial infections caused by Staphylococcus aureus strains resistant to methicillin and multiple antibiotics have reached epidemic proportions in Melbourne, Australia, over the past 5 years. Plasmid analysis of representative clinical isolates demonstrated the presence of three classes of plasmid DNA in most strains. Resistance to gentamicin, kanamycin, and tobramycin was usually mediated by an 18-megadalton plasmid but could also be encoded by a related 22-megadalton plasmid. Two distinguishable plasmids of 3 megadaltons each endowed resistance to chloramphenicol, and the third class consisted of small plasmids, each approximately 1 megadalton in size, with no attributable function. An extensive array of resistance determinants, including some which have usually been associated with a plasmid locus, were found to exist on the chromosome. Evidence that resistance to gentamicin, kanamycin, and tobramycin is chromosomally encoded in some clinical isolates suggests that this determinant may have undergone genetic translocation onto the staphylococcal chromosome.

Antibiotic-resistant staphylococci in a teaching hospital

A large, continuing outbreak of infection and colonisation with a Staphylococcus aureus which is resistant to methicillin and gentamicin is reported. Affected patients and staff members seen between September, 1980, and August, 1981, are reviewed in detail. Methods of management of such persons and their treatment, if required, are discussed. The antibiotic-resistant Staph. aureus is readily disseminated in hospitals and may cause outbreaks of infection in wards, which require isolation of affected patients in the attempt to control the problem. It is suggested that a special isolation unit is needed. Use of the few effective antibiotic agents should be restricted. Despite these measures, the spread of this organism may not be contained.