Use of random amplified polymorphic DNA to assess repeated isolates of Acinetobacter baumannii [2]

Letters to the Editor

doi:10.1053/jhin.2002.1336

Non-touch fittings in hospitals: a possible source of Pseudomonas aeruginosa and

Legionella spp.

Sir,

We read with interest the article by Halabi et al.

and agree with the authors that non-touch fittings, in particular taps without temperature selection, provide ideal growth conditions for Pseudomonas aeruginosa, and that it is almost impossible to decontaminate this type of tap.

In our hospital, three non-touch water taps with- out temperature selection were installed during improvement work in the haematology ward. These taps were installed in the sanitary facilities for use by healthcare workers, located at the entrance of the isolation unit and in the corridor serving the isolation rooms. Each isolation room was provided with con- ventional water taps. The same water source, from a central pipe system, supplied all the taps. Before re- opening the haematology ward in December 2001, the hospital infection control team checked the bac- teriological quality of the water in each sanitary facility. The usual procedure of allowing the water to flow for 10 min and flaming the water outlet was not performed to ensure that the water samples from the ward were authentic. The technical treatment of specimens was identical to that done by Halabi et al.

Colonies that grew on cetrimide agar were identified biochemically as P. aeruginosa using the API-20 NE (BioMeÂrieux) identification system and genotyped using pulsed-field gel electrophoresis.

None of the specimens collected from the conventional taps in the rooms revealed the presence of P. aeruginosa, whereas all three non-touch taps were contaminated with P. aeruginosa (two were heavily contaminated).

In January 2002, the taps were disinfected six times using chlorine solution applied for 15 min, followed by microbiological testing on the 18 specimens. Only two specimens were negative for P. aeruginosa. On February 11, the non-touch taps were removed, replaced by conventional taps and disinfected using chlorine solution. Microbiological tests were per- formed on water from the taps on February 12, 15

0195±6701/03/010077‡06 $35.00/0 &2003 The Hospital Infection Society

Journal of Hospital Infection(2003)53: 77±82

and 18 and in May and August. All these 15 speci- mens were negative for P. aeruginosa. Three geno- types were identified in the P. aeruginosa strains isolated, each genotype corresponded to one of the non-touch taps. The results from microbiological analyses on water from the conventional and non- touch taps, and from genotyping indicated that the central pipe system was not responsible for the con- tamination and thus incriminated the non-touch taps. There seems to be an advantage in eliminating the need to touch taps in hospitals, but it appears to be very difficult to remove contamination with bio- cides and disinfectants. In conclusion, we agree with Halabi et al.,

that infection control teams should be encouraged to evaluate the use of non-touch fittings in high-risk areas in hospitals.

References

1. Halabi M, Wiesholzer-Pittl M, SchoÈber JJ, Mittermayer H. Non-touch fittings in hospitals: a pos- sible source of Pseudomonas aeruginosa and Legionella spp. J Hosp Infect 2001; 49: 117±121.

2. Talon D, Cailleaux V, Thouverez M, Michel-Briand Y.

Discriminatory power and usefulness of pulsed-field gel electrophoresis in epidemiological studies of Pseudo- monas aeruginosa. J Hosp Infect 1996; 32: 135±145.

doi:10.1053/jhin.2002.1295

Use of random amplified polymorphic DNA to assess repeated isolates of

Acinetobacter baumannii Sir,

Acinetobacter baumannii are ubiquitous Gram- negative coccobacilli

that are important agents of nosocomial infection.

These organisms can be iso- lated from normal individuals

and from pharynx, digestive tract and skin of hospitalized patients.

In hospital settings these bacteria can be recovered from the environment,

from medical and non-medical R. Leprat,

V. Denizot, X. Bertrand and D. Talon

Service d'HygieÁne HospitalieÁre,

CHU Jean Minjoz,

25030 BesancËon, France

equipment

and from the hands of healthcare workers.

Thus the interpretation of culture results must take into account colonization and potential environmental contamination.

The usual bacter- iological criterion is the repeated recovery of the same isolate.

We used random amplified poly- morphism of DNA (RAPD) to assess repeated iso- lates of A. baumannii recovered from four samples obtained on three consecutive days from the infected episiotomy site of a patient hospitalized in an inten- sive care unit.

The four samples were analysed by standard bac- teriological procedures. The identification of A. baumannii was done with API20 NE system, malonate and citrate utilization and culture at 44

C.

Antibiotic susceptibilities were studied by disk dif- fusion following NCCLS recommendations. RAPD was done with the M13 and DAF4 primers (Genome Biotechnologies France) and 2 U of Taq polymerase (Promega). A. baumannii ATCC 19606 and a non- linked isolate were used as controls.

The four patient isolates had the same API20 NE code (0001073). This code was different from the codes obtained with the reference strain (0041471) and the non-linked isolate (1041073). The four patient isolates were sensitive only to imipenem.

Three of these isolates were also resistant to tobra- mycin. The RAPD profiles obtained with the DAF4 primer were identical for the patient isolates and were different from those of the ATCC isolate and the non linked isolate (Figure 1). The same results were obtained with the M13 primer (data not shown).

The possible occurrence of sample contamination due to colonization of the patient, equipment, environment and hands of staff raises the question of the need for antibiotic treatment, especially as these bacteria are often multi-resistant as in this case. A unique API20 NE biotype was found for the four patient isolates. Nevertheless the study of A. baumannii isolates responsible for nosocomial infections outbreaks in different regions of Europe showed that isolates identical by DNA±DNA hybridization or by ribotyping can have different biotypes.

The four patient isolates had slightly different antibiotic resistance profiles but this difference does not mean that these isolates are non- identical, given the genetic instability by acquisition or lost of plasmids or transposons.

Differences in antibiotic resistance patterns of genetically identical A. baumannii isolates have already been reported.

Thus the biotype and the antibiotic resistance

phenotype cannot be used alone to differentiate A. baumannii isolates.

Genotypic tools are usually used in epidemiologi- cal studies to compare isolates recovered from dif- ferent patients. We used RAPD to compare four isolates recovered from the same patient. This tech- nique revealed identical profiles, reflecting the pos- sibility that the isolates were responsible for infection and not for contamination of the samples. This approach has already been used to assess multiple isolates of coagulase-negative staphylococci from blood cultures using pulsed-field gel electrophor- esis,

in an attempt to distinguish true bacteraemia from skin contamination. In this study,

several episodes of bacteraemia would have been wrongly assessed if only biotype and antibiotype had been determined.

RAPD is a useful tool for the study of A. baumannii isolates. This technique is simple, rapid and rela- tively inexpensive. It may be useful as a routine to help interpret bacteriological results and facilitate the decision making of clinicians.

Acknowledgement

The work was supported by a grant from the Pro- gramme TheÂmatique d'Appui aÁ la Recherche Sci- entifique (PROTARS P1T2/04).

1 2 3 4 5 6

Figure 1 RAPD profiles of Acinetobacter baumannii isolates with primer DAF4. Lanes 1 to 4: isolates from a single patient; lane 5: non linked isolate; lane 6:A. baumanniiATCC 19606.

78 Letters to the Editor

References

1. Bergogne-Berezin E , Towner KJ. Acinetobacter spp.

as nosocomial pathogens: microbiological, clinical, and epidemiological features. Clin Microb Rev 1996; 9:

148±165.

2. Allen DM, Hartman BJ. Acinetobacter species. In:

Mandell GL, Benett JE, Dolin R, Eds. Principles and Practice of Infectious Diseases, 5th edn. Edinburgh:

Churchill Livingstone 2000; 2339±2344.

3. Forster DH, Daschner FD. Acinetobacter species as nosocomial pathogens. Eur J Clin Microbiol Infect Dis 1998; 17: 73±77.

4. Ayats J, Corbella X, Ardanuy C et al. Epidemiological significance of cutaneous, pharyngeal, and digestive tract colonization by multi-tesistant Acinetobacter bau- mannii in ICU patients. J Hosp Infect 1997; 37: 287±295.

5. Tankovic J, Legrand P, De Gatines G, Chemineau V, Brun-Buisson C, Duval J. Characterization of a hospital outbreak of Imipenem resistant Acinetobacter baumannii by phenotypic and genotypic typing methods. J Clin Microbiol 1994; 32: 2677±2681.

6. Dijksoorn L, Aucken MH, Gerner-Smidt P, Kaufmann ME, Ursing J, Pitt LT. Correlation of typing methods for Acinetobacter isolates from hospital outbreaks. J Clin Microbiol 1993; 31: 702±705.

7. Dijksoorn L, Aucken MH, Gerner-Smidt P et al.

Comparison of outbreak and non outbreak Acinetobacter baumannii strains by genotypic and phe- notypic methods. J Clin Microbiol 1996; 34: 1519±1525.

8. Toldos CM, Yague G, Ortiz G, Segovia M. Assessment of multiple coagulase-negative staphylococci isolated in blood cultures using pulsed-field gel electrophoresis.

Eur J Clin Microbiol Infect Dis 1997; 16: 581±586.

doi:10.1053/jhin.2002.1330

A possible grading system for healthcare- associated infection surveillance Sir,

The SENIC study demonstrated the value of sur- veillance as part of an infection control programme

in preventing nosocomial infections and reducing excess health costs with which they are associated.

It has since led to the development, albeit after a consider- able period of time, of other surveillance systems, including those in the UK.

Many politicians, as well as healthcare commissioners, have now been made aware of the efficacy and importance of surveillance

systems for healthcare-associated infection (HCAI).

The problem is that surveillance, whilst considered to be a means by which HCAI can be reduced, is applied to many processes that will only provide data on the number of events and will not in themselves reduce infections. For surveillance to have an impact on the incidence of HCAI it must include feedback to those individuals who are in a position to prevent HCAI through change in practice. We propose a grading system that should clarify the objectives and likely outcomes of various surveillance programmes (Table I). It is essential that those commissioning and undertaking these programmes areawareof what both the objectives and likely outcomes of the surveillance actually are, otherwise misconceptions will occur and scarce resources will be wasted.

There are fundamental differences in the problems posed by infections that present in the community and those associated with healthcare settings. In the community the major concern is preventing the spread of certain infectious diseases, such as tuber- culosis, meningococcal and gastrointestinal infec- tions. The objectives of surveillance systems in these situations are primarily to do with estimating the burden of these diseases and monitoring their trends.

Data tend to be collected passively, at a population level, with crude denominators and limited risk factor data. Such surveillance provides information to adjust community-level prevention measures such as immunization or health education regimes. We would describe this as Level 1 surveillance.

Level 1 surveillance may still be relevant in healthcare settings to detect cases of communicable infections, such as MRSA or gastrointestinal infec- tions, thus instigating infection control measures before spread can occur. However, as `outbreaks' of infection account for less than 4% of all infection acquired in hospital

a more important objective for surveillance in healthcare facilities is the provision of data for quality improvement programmes. For this, a different level of surveillance is required. Infections associated with healthcare are caused by a diverse group of micro-organisms. HCAI usually occur in a highly vulnerable population, and mostly in association with invasive procedures rather than through the spread of highly communicable organ- isms. The underlying causes are usually multi- factorial, and they are rarely amenable to prevention by single, simple interventions. For example, factors that may contribute to the risk of developing surgical wound infection include: environmental controls in theatre; the surgeon's experience, skill and technique;

R. AitMhand*, N. Elmdaghri*, L. Barrouy, A. Soukriz and M. Benbachir*

*Microbiology Laboratory, ySurgical Intensive Care Unit, and zFaculte des Sciences I, IbnRochd University Hospital, AinChock, Casablanca, Morocco

Letters to the Editor 79