Outpatient parenteral antimicrobial therapy: Recent developments and future prospects.

Patients with serious infections requiring parenteral antimicrobial therapy are usually hospitalized for treatment. For certain conditions, however, administration of parenteral antibiotics outside the hospital setting may be safe, efficacious, convenient for patients and cost-beneficial. Outpatient parenteral antimicrobial therapy (OPAT) was developed in the US initially and its use has expanded globally during the past three decades. A wide variety of infections are amenable to treatment by OPAT. Once-daily agents such as ceftriaxone or teicoplanin and, more recently, antimicrobials such as ertapenem or daptomycin have been used for OPAT. The use of higher doses and less-frequent dosing of existing agents is being explored, and exciting new developments include the emergence of agents with broader-spectrum activity against drug-resistant organisms and the use of antifungal agents in the OPAT setting. Future prospects in OPAT include the use of more recently launched drugs such as telavancin, as well as drugs in development, including dalbavancin (Durata Therapeutics Inc) and omadacycline (PTK-0796; Novartis AG/PARATEK Pharmaceuticals Inc). This review outlines recent developments in, and future prospects for, the antimicrobial agents used in OPAT.

Staphylococcus lugdunensis endocarditis following cardiac catheterisation.

We report the case of a 77 year old with Staphylococcus lugdunensis endocarditis following cardiac catheterisation via a femoral approach. We underline the association between this pathogen and inguinal skin breaks, and discuss the potential diagnostic pitfalls in clinical and laboratory diagnosis.

Native-valve endocarditis caused by Staphylococcus lugdunensis.

Coagulase-negative staphylococci cause about 5% of native-valve endocarditis. Staphylococcus lugdunensis, a recently-described species of coagulase-negative staphylococci, has been reported to cause destructive native-valve endocarditis with a high mortality. We report four consecutive cases of definite Staphylococcus lugdunensis native-valve endocarditis by the Duke criteria over a 4-year period. All patients required urgent aortic valve replacement 1-5 days after admission, and recovered. An intriguing, aspect in the presentation of these patients was a history of vasectomy and inguinal skin breaks in the immediate period preceding the occurrence of endocarditis.

When should healthcare workers be screened for methicillin-resistant Staphylococcus aureus?

The role of screening of healthcare workers (HCWs) in the control of methicillin-resistant Staphylococcus aureus (MRSA) is controversial. It is recommended in guidelines by expert groups in both North America and the United Kingdom, although the role of MRSA carriage by HCWs in outbreaks is not clearly defined. The present report describes the spread of a distinct strain of MRSA to patients by a single HCW on three separate occasions over 27 months. The isolates from this HCW and patient contacts were shown to be indistinguishable by antibiogram and repetitive extragenic palindromic polymerase chain reaction (REP/PCR); none were typeable by lytic phage-typing. Throat carriage of the MRSA probably recurred in this HCW, despite attempts to eradicate it on three occasions. Over the same period, nine other small clusters were seen in the Oxford Hospital Group, involving 66 patients and 22 HCWs colonized, or occasionally infected, with a variety of MRSA strains. In none of these instances could HCWs be implicated in the initiation of an outbreak. The advantages of a screening policy include the determination of the full extent of MRSA-colonization and work exclusion; the disadvantages include detection of transient nasal carriage, disruption of staff routine and stigmatization. Screening of HCWs can be a valuable tool in the control of MRSA outbreaks but it should be used selectively. This strategy remains an important part of a control programme.

The value of cerebrospinal fluid enrichment culture in the diagnosis of acute bacterial meningitis.

The records of cerebrospinal fluid (CSF) examinations for the three-year period ending 30 September 1991 were studied retrospectively. From 3,161 examinations, 66 pathogens were detected, 64 of which were from primary agar plate culture. Enrichment broth culture yielded 219 isolates of which 217 were likely contaminants. Only two pathogens were isolated by enrichment, and in both samples the CSF leucocyte counts were abnormal. The use of enrichment broth culture should be confined to CSF specimens with abnormal leucocyte counts and/or Gram stains.

Molecular epidemiology of a multiple strain outbreak of methicillin-resistant Staphylococcus aureus amongst patients and staff.

Since methicillin-resistant Staphylococcus aureus (MRSA) isolates are not endemic in our hospital, which is a tertiary referral centre, the finding of 13 MRSA isolates from 12 patients associated with an acute vascular surgery ward between October 1993 and December 1993 prompted further epidemiological and laboratory investigations. Two strains were distinguished by antibiogram and phage-typing. One strain, resembling EMRSA-16, colonized six patients and was probably introduced from another hospital in the Oxford Region. Five other patients were colonized by a second strain, gentamicin-resistant and non-typable by phage-typing, probably introduced into the hospital 12 months previously by a patient from Nairobi, Kenya. A 12th patient was colonized by both strains simultaneously. Of 46 staff members screened three were colonized--one by an EMRSA-16 strain, a second by the gentamicin-resistant 'Nairobi'-strain and a third member carried yet a further distinct MRSA strain. The healthcare worker colonized by the 'Nairobi'-strain had been carrying the isolate 12 months previously and was the likely source of this strain. These isolates were also characterized by the repetitive extragenic palindromic-polymerase chain reaction (REP-PCR), a novel PCR-based methodology which has not been previously used in characterizing Staphylococcus aureus in an outbreak. This method corroborated the strain classifications provided by the traditional methods, confirming that there had been spread of two strains simultaneously. Our study demonstrates that multiple strains of MRSA may circulate amongst patients and staff during an outbreak, patients may be colonized by more than one strain simultaneously and long-term staff carriage (> 12 months) may be an important source of colonization in patients. REP-PCR is a rapid and effective molecular typing method for MRSA.

Naturally occurring PIA/PIB hybrids of Neisseria gonorrhoeae.

The major outer membrane protein of Neisseria gonorrhoeae, Por, functions as a porin and is thought to occur as one gene with two alleles. The immunologically distinct epitopes of the two subclasses, IA and IB, have allowed the development of serotyping schemes. Clinical isolates of N. gonorrhoeae are believed to express only a single type of Por, either IA or IB. We have encountered two clusters of isolates that react with antibodies to both IA and IB Por. Isolates within the clusters are indistinguishable by the phenotypic characteristics tested. In addition, the amplification of the por gene in representative isolates showed that the por gene of the hybrids gave similar restriction digest patterns within but not between the clusters.

Fatal pulmonary infection due to Mycobacterium fortuitum.

Environmental (atypical, opportunist, other) mycobacteria were first isolated nearly a century ago. The classification of these "other than Mycobacterium tuberculosis" organisms was initially chaotic until Runyon proposed a scheme of four groups in 1959. Mycobacterium fortuitum is a member of group IV: Rapid growers. These ubiquitous terrestrial and aquatic forms contaminate water supplies, reagents, and clinical samples. They may colonise the respiratory systems of patients whose local defence mechanisms have been impaired or those with congenital and acquired immune defects. They can also cause disease in immunocompetent individuals. There have been fewer than 20 published cases of pulmonary infection caused by M fortuitum. A further case is reported of fatal pulmonary infection in an elderly patient with long standing chronic obstructive airways disease (COAD). He had left upper zone shadowing on chest radiography and lung abscesses at post mortem examination yielded only M fortuitum.