Bacterial resistance has become one of the major challenges in the therapy and control of nosocomial infections. Studies assessing the prevalence of MDROs can help to improve the understanding of the epidemiology of MDROs as well as increase the awareness to this problem and thus foster the development and implementation of evidence based strategies to combat bacterial resistance.

Our study is the third survey in a row to assess the emergence of MDROs and Clostridium difficile as well as staffing with infection control personnel and MDRO screening policy in German hospitals. As in the previous surveys, we used a pragmatic, easily accessible approach by collecting routine surveillance data that has to be present in hospitals by law in Germany. By limiting the prevalence survey to intensive care units, surgical and medical wards, our data allows comparisons between primary, secondary and tertiary level hospitals. Furthermore, as this survey uses the same method as the previous surveys, temporal comparisons are possible in principle, too. When comparing the three surveys, the most obvious result is the steep increase in participating hospitals that grow from 9 hospitals in 2010 to 62 hospitals in 2012 and 364 hospitals in this survey. The increase from the first to the second survey can be explained by the support from the Action Group Infection Prevention (“Initiative Infektionsschutz”) (AGIP) and Ipse communication GmbH that provided an extensive list of e-mail contacts of hospitals. The 4-fold increase in the return rate from the former to this survey however can be interpreted as an expression of the growing awareness to MDROs and public acceptance of our easily accessible approach that depicts the “true” clinical situation as seen by health care workers and infection control personnel in the hospitals.

With the amendment of the German Protection against Infection Act in 2011, the recommendations from the German national committee for infection prevention Commission on Hospital Hygiene and Infection Prevention (KRINKO), the German national committee for infection prevention, became obligatory for hospitals and other health care facilities. As a consequence, staffing with infection control personnel became mandatory. The recommendations for staffing by the KRINKO are based on a risk assessment that take into account the treatment range of the medical provider as well as the individual risk profile of the treated patients [18]. However, a recent report of the federal government on nosocomial infections and bacterial resistance saw great variations in the compliance with this standard [20]. Due to the requirements for staffing with infection control consultants and infection control nurses, 82.2 % - 85.6 % (median: 84.8 %) and 69.7 % - 80.0 % (median: 74.8 %) of hospitals met the KRINIKO-recommendation, respectively [18, 20]. While still not perfect, our survey shows a good compliance with the recommendations as 84.8 % of hospitals met the staffing needs for infection control nurses and 74.8 % for infection control consultants. This again points to the assumption, that appropriate staffing with infection control personnel fosters hospital epidemiology and awareness and countermeasures against bacterial resistance.

Our data implies that there is still a relevant number of unknown MDRO cases, as the reported prevalence rates of most MDROs tends to be higher in hospitals that screen for particular MDROs than in hospitals that do not. While this problem may be negligible for MRSA as most hospitals reported to have some kind of screening in place, it may be influential for VRE and Gram-negative MDROs, as the majority of hospitals still reported to have no active screening policy.

Direct comparisons between prevalence rates reported in this survey and other surveys, including our former studies, should be made with caution as the samples are not identical and it is therefore unclear whether the same hospitals have participated. Still, comparisons between point prevalence studies have been made regardless of these problems [21–23]. Assured by the large number of participating hospitals in our study we will therefore discuss some general comparisons between our study and other studies to give an impression how our data fits to other surveys. The German part of the European point prevalence study of the European Centers for Disease Control (ECDC-PPS) from 2011 has been published as public report by the National Reference Center for Surveillance of Nosocomial Infections [21]. While the European point prevalence study dates back from 2011, the prevalence of nosocomial infections due to MRSA (ECDC-PPS (Germany): 0.17 %, our survey: 0.17 %), CD (ECDC-PPS (Germany): 0.30 %, our survey: 0.26 % and 3MRGN-EC (ECDC-PPS (Germany): 0.15 %, our survey: 0.12 %) fit well to our data, while the prevalence of nosocomial infections due to VRE is much higher in our survey (0.12 %) compared to the data from the German ECDC-PPS (0.02 %). This would fit to the increase in the VRE prevalence as recently reported by the National Reference Center for Surveillance of Nosocomial Infections [24].

A direct comparison to prevalence rates reported by the German Surveillance System of Nosocomial Infections in Hospitals (KISS) on the other hand is not possible, as this system reports incidences and prevalence rates of particular of some MDROs but uses an entirely different way of data collection and statistics [22, 25]. For example, MRSA-KISS reports MRSA prevalence rates and incidences on a yearly base, but does not separate by medical specialties, infections and colonizations. Moreover, prevalence rates and incidences are not calculated per hospital but pooled over all participating hospitals and over the whole time [26]. Other KISS modules (ITS/Stations-KISS) on the other hand does report prevalence rates and incidences divided by medical specialties, infections and colonizations but not on a yearly base but pooled from 2013 [27].

Our results underlay that prevalence data reported by KISS cannot be used as valid indicators for the daily prevalence of MDRO patients in hospitals. This further explains why the situation felt by health care workers and infection control personnel in the hospitals does not fit well to the reported prevalence data, as the perceived epidemiological situation is mainly determinated “burden”.

Compared towards our former survey from 2012, MRSA, VRE, 3MRGN-EC, 3MRGN-KS and CD remain the most prevalent pathogens in all levels of care and types of wards (Table 7) [12]. The prevalence of MRSA and VRE almost matches the ones from the former survey. Therefore MRSA still remains the most prevalent and most prominent MDRO in German hospitals. The prevalence of 3MRGN-EC and 3MRGN-KS are both somewhat lower compared to the prevalence of ESBL-EC and ESBL-KS reported in 2012, but confidence intervals broadly overlap. The trend to a lower prevalence can be explained by the stricter definition for 3MRGN is than for ESBL. Only CD infections had an obviously lower prevalence in comparison to 2012. An in depth comparison showed that especially the prevalence on surgical and internal ward was lower compared to 2012 (with confidence intervals non overlapping), while the confidence intervals did broadly overlap for ICUs. Whether this indicates a true reduction in CD cases (e.g. caused by better antibiotic stewardship), shorter duration of stay of CD cases (reducing the chance to be detected in a point prevalence study) or other factors, remains unclear. Either way, CD still remains one of the most prevalent pathogens.

Table 7 Data of mean prevalence of the most prevalent MDROs of point prevalence survey 2012 [12] and 2014 Full size table

Our study has several limitations that should be acknowledged when interpreting the data. First, as we used routine data, our results have the typical constrains associated with this type of data. We deliberately gave no extra definition for cases, or to distinguish between infections/colonisations, nosocomial and hospital acquired cases. This is a complementary approach to other epidemiological studies on the same topic that use generic definitions (e.g. CDC-definitions) to classify cases.

The obvious drawback of our method is that there may be some differences in the definitions between hospitals or even wards. However, our approach has the advantage that our results depict the “true” clinical situation as seen by health care workers and infection control personnel in the hospitals. Moreover, this data are used for calculating of reimbursement by health insurances, too.

Second, as the survey was voluntary and anonymous, we have no means to validate the results and our sample may not be representative. Still, with almost 74,000 patients from 329 hospitals, our survey uses data from more than 16 % of German hospitals. It is therefore the largest study of its kind in Germany with more than twice as many participating hospitals as the in the German part of the ECDC point prevalence study from 2011 [21]. This underlies that pragmatic surveys to collect routine surveillance data are an attractive and replicable way to gather epidemiological data with limited resources. Voluntariness and self-reporting are an issue for other surveys, like the German hospital infection surveillance system (KISS), too. As in the previous surveys, data was collected directly at the wards or using electronic systems by trained personnel in most hospitals. Therefore, we are quite confident that our results give a good estimate of the situation in German hospitals.

Our results should be used by infection control personal to raise awareness towards bacterial resistance and foster infection control measures. Further studies should follow up our results and expand to other health care settings as rehabilitation and nursing homes.