This review of Acinetobacter outbreaks summarizes factors related to the presence and recognition of organism transmission and describes the implementation of control and prevention measures directed at limiting spread. Exogenous transmission of Acinetobacter should be considered when infections are endemic and when case rates increase. Increasing or new antimicrobial resistances in a collection of isolates also suggest transmission, and transmission can be definitively confirmed when isolates are found to be indistinguishable from or related to one another by a discriminatory genotyping test. An investigation for a common source should be conducted. When a common source cannot be found and eliminated, or once an endemically transmitted organism is established, containment or prevention efforts may require aggressive interventions, complex interventions, or both. Colonization at multiple sites, the relative ease of induction of antibiotic resistance in the organism following patient exposure to multiple drugs, and long-term environmental survival provide enhanced opportunities for the transmission of Acinetobacter between and among patients. New approaches and interventional trials are needed to define effective measures for the prevention and control of Acinetobacter infections.

An outbreak investigation was conducted to determine if an increase in bloodstream infections (BSIs) in patients with central venous catheters (CVC) had occurred. Because other methods of obtaining CVC days were not feasible, we used an estimation method based on a random 5% sample of medical records to determine the proportion of days that a CVC was present for each of three patient units. This calculated ratio was used to estimate the total CVC days for each unit. A cohort study was conducted in which the BSI rates before and during needleless device use were compared. This article describes the methods used to calculate this estimated denominator and discusses the need for such a denominator to be used by infection control practitioners when prospective collection of CVC days is not possible.

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) has increased in communities and in healthcare facilities in the United States since the mid-1970s. Although MRSA often is thought of as a nosocomial infection problem because it is encountered in facilities of all types and sizes, it also causes many community-acquired infections. Approaches to control of MRSA vary widely, and there is lack of agreement on the most appropriate measures to control MRSA in healthcare facilities. The wide variation in approaches is due, in part, to the lack of data establishing the efficacy of specific control measures. As a result, the approaches that have been advocated have resulted in confusing and often conflicting recommendations and control measures. In some settings, there also have been unreasonable barriers and administrative hurdles that delay or prevent the transfer of patients between acute care and nursing (extended care) facilities.

Forty-three intubated and mechanically ventilated patients in five intensive care units (ICUs) of one hospital developed respiratory colonization or infection with Acinetobacter calcoaceticus subspecies anitratus over a 16-month interval. Neither the frequency nor rate of A anitratus isolation exceeded the hospital endemic norms. Single isolates from 34 of the patients were subtyped by plasmid DNA analysis, two biotyping systems and antimicrobial susceptibility to 24 drugs. Plasmid DNA fingerprints were distinct in 18 isolates (they differed from each other and all others), similar in two and identical or similar in ten. The latter group of isolates were recovered from patients in four ICUs. Reproducibility of biotyping was poor. Neither biotyping nor antimicrobial susceptibility were successful in identifying sameness among the group isolates nor differences among other isolates. We conclude that plasmid DNA fingerprinting should be used to assess the possibility of multiple patient transmissions of the same A anitratus strain in the absence of an obvious outbreak.

Clinical, bacteriologie, epidemiologic and hospital infection-control observations related to an inter-hospital outbreak of methicillin-resistant Staphylococcus aureus are described. The outbreak involved 66 patients at the University of Oregon Health Sciences Center (UOHSC) and its closely affiliated VA hospital, the Portland VA Medical Center (PVAMC). No environmental source of infection was identified; person-to-person transmission was most likely responsible for its spread. Surveillance cultures demonstrated nasal colonization in house staff and nursing personnel at both hospitals. Inter-hospital transfer of infection was, in all likelihood, achieved via nasal carriage by a single physician. Case-control analysis indicated a significantly increased risk (p < 0.05) of acquisition of infection related to age, number of days hospitalized, severity of underlying disease and number of invasive procedures. Prior antibiotic receipt was a significant risk factor when analyzed by univariate analysis (p < 0.01), but, in contrast to previous studies, this was not a significant risk factor (p > 0.05) when related variables were controlled by multivariate analysis. Prevention of spread of infection by routine infection control measures was less effective at PVAMC than at UOHSC. Patients at PVAMC were significantly older and had longer durations of hospitalization (p < 0.05). Antimicrobial therapy of colonized patients and personnel appeared to assist in the control of the outbreak at PVAMC. Antimicrobial therapy with topical bacitracin and oral rifampin, alone or in combination with oral trimethoprim-sulfamethoxazole, was effective in eliminating colonization with methicillin-resistant S. aureus. [Infect Control 1981; 2(6):453-459.]

This study describes the evaluation of 108 patients who had indwelling urethral catheters for acute medical and surgical indications. Patients were evaluated daily, and cultures from bladders and drainage bags were obtained. Appropriateness for continuing catheterization was assessed using preset criteria. Twenty-five patients developed urinary tract infections. Exposure to antibiotics and a shorter duration of catheterization were the only factors that correlated significantly with a delayed onset or decreased prevalence of infection. Factors found to have insignificant effects included age, sex, maintenance of the closed system, underlying host disease status, catheter type, and reason for catheterization. No collection systems with one way valves were used, but significant colony counts in drainage bag urine preceded urinary tract infection in only two patients. Thirty-six percent of the total 562 catheter days were judged unnecessary. A major emphasis must be placed on prompt catheter removal if the prevalence of nosocomial urinary tract infections is to be reduced substantially in a cost-effective manner [Infect Control 1981; 2(5):380-386.]